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Open Access Article
1 - Reviewing methods of analysis and evaluation of seismic safety of arched concrete dams
Mohammadreza Fedai-Tehrani Elham YbarehpourArched concrete dams are three-dimensional structures that, in terms of their special shape resembling a huge shell, transfer the water pressure from the tank to their stone supports. Besides the forces of weight, hydrostatic pressure and thermal stresses, another signi MoreArched concrete dams are three-dimensional structures that, in terms of their special shape resembling a huge shell, transfer the water pressure from the tank to their stone supports. Besides the forces of weight, hydrostatic pressure and thermal stresses, another significant force that the dam's structural system must withstand is the dynamic forces generated by earthquakes. In such dams, there is a possibility of non-linear behavior due to the change in the location of the two faces of the contraction joints, cracking, corrosion, or non-linear behavior of the concrete of the dam body depending on the intensity of the earthquake. Dynamic analysis of time history, assuming that the dam body is an integrated structure with elastic behavior, usually leads to the creation of significant tensile arch stresses in the upper levels of the dam, which is not in accordance with reality. Since the arch dams are built as ridge blocks, due to the opening and closing of the contraction joints during the earthquake, the released tensile stresses and internal forces are redistributed from the arch performance mode to the ridge performance. As a result, by reducing the level of tensile stresses and energy consumption as a result of joint closure, the risk of concrete cracking and dam destruction is greatly reduced. Manuscript profile -
Open Access Article
2 - Jurisprudent Consideration of Becoming Spiritual right as Costs and Prohibition of Treatment in them
Morteza Pouyanright is in common with an effect like authority whether we tell thatright is the same possession or not. And the authority of propertiesin rights is enough to decide that any disposal in the human’s rightproperties ,without taking a permission of its owner,isnotl Moreright is in common with an effect like authority whether we tell thatright is the same possession or not. And the authority of propertiesin rights is enough to decide that any disposal in the human’s rightproperties ,without taking a permission of its owner,isnotlegitimate. And the spiritual right which don’t exist as concreteobjects in reality of the world and one cannot be possessive of it.but rather it is a kind of intellectual and customary abstractions thatwe can prove it that both could be a cost in a sale even if we doubtin its judgment of legitimacy or non-legitimacy.we can ,on the lawof legitimacy of transfer ,say that the transfer is in the case.The conclusion is: first the owner of right has a kind of authorityaccording to right which belongs to him. And nobody can act on itwithout his permission. For instance without the permission of itsowner nobody have right to publish one’sroyaltyand his scientifictheories or copy a cd secondly the contract of rights in the way ofsale like other contracts are legitimate. Manuscript profile -
Open Access Article
3 - Laboratory evaluation of the effect of permeable vanes distance using six-pillar concrete elements on the bend migration
Ebrahim Najjaran Amir Abbas Kamanbedast Mahmood Shafai Bejestan Alireza Masjedi Hooshang HasonizadehPermeable vanes are structures that move the erosion of the outer bank of the river by diverting the erosive flow from the outer arch of the river to its center. In this study, the pattern of erosion and sedimentation around the hydraulic structure in the installation c MorePermeable vanes are structures that move the erosion of the outer bank of the river by diverting the erosive flow from the outer arch of the river to its center. In this study, the pattern of erosion and sedimentation around the hydraulic structure in the installation conditions of different distances from each other has been studied. Six-pillar concrete elements are materials that form a permeable structure overlapping and are applicable without drying the riverbed. These blocks need to be examined for how the structure works. With this concept, in the present study, the performance of this structures were performed in a laboratory channel with a width of 60 cm and a 180 degree flume under different hydraulic conditions (Fr = 0.227, 0.244, 0.261, 0.278). The required data were measured at different distances (5L, 6L, 7L, 8L) with an effective length equal to 20% of the width of the flume (L=12cm). Control experiment was performed in similar conditions to other scenarios without groins construction. Comparison of the results of the control and main experiments showed that the construction of permeable rectangular groin with a distance of 5L had the best efficiency in reducing the maximum depth of scour at the outer bank compared to the control experiments equal to 70.1% and 57.9% in Froud numbers of 0.227 and 0.261, respectively. Manuscript profile -
Open Access Article
4 - CO2 emissions reduction by using local mineral pozzolan as part of cement in concrete with a pollution reduction approach
Mojtaba Rangrazian Rahmat Madandoust Reza Mahjoub Mehdi RaftariBackground and Objective: Global warming is caused by the emission of greenhouse gases, mainly (CO2). Reducing greenhouse gases and monitoring the environment are important goals of today's mankind. Cement factories are the main producers of greenhouse gases. The main g MoreBackground and Objective: Global warming is caused by the emission of greenhouse gases, mainly (CO2). Reducing greenhouse gases and monitoring the environment are important goals of today's mankind. Cement factories are the main producers of greenhouse gases. The main goal of this research is to find a material with cement properties (pozzolan) that can be replaced in a part of concrete cement with the aim of reducing cement consumption and reducing CO2 greenhouse gas emissions. The local mineral pozzolan under research has similar properties to world-famous pozzolans and has the relevant standards.Material and Methodology: To find the optimal amount of pozzolan in the concrete, In Sep. 2021, four cases of 5, 10, 15 and 20% by weight was studied and its effect on concrete compressive strength and CO2 emissions and its ability to reduce pollution Environmental was evaluated in comparison with conventional cement concrete. Findings: Experiments showed that the best amount of replacement of this pozzolan to cement in concrete is 15% by weight and increases the strength by 2.4%. Also, this pozzolan emits less CO2 than normal cement concrete equal to 15.20 kg/m3.Discussion and Conclusion: Considering the favorable effects of this pozzolan in strengthening the structure and reducing the consumption of cement in concrete, it can be introduced as a cement-reducing and environmentally friendly material. Manuscript profile -
Open Access Article
5 - Synthesis of Environmentally Friendly Activated Alkali Concrete (Geopolymer) Based on Bentonite
A Esparham -
Open Access Article
6 - Non-Destructive Assessment of Concrete Quality Produced with Riverbed Sand and Drainage Sand as Fine Aggregates
Aderemi__A__Alabi Alabi Ayobami__Eniola__Agboola Agboola Joseph__Olawale__Akinyele Akinyele Victor MakindeIn this work, the effect of fine aggregates from two different sources on the quality and strength of concrete was determined using UPV measurements. The concrete samples were produced using a nominal mix ratio of 1: 1½: 3 and water-cement ratio of 0.55, with three diff MoreIn this work, the effect of fine aggregates from two different sources on the quality and strength of concrete was determined using UPV measurements. The concrete samples were produced using a nominal mix ratio of 1: 1½: 3 and water-cement ratio of 0.55, with three different aggregate sizes (3/8, ½ and ¾ inches) of granite mixed separately with sand obtained from Ogun river and a local drainage in Abeokuta, Southwestern, Nigeria. UPV was measured through each sample on days 1, 7, 14, 21 and 28 after curing using Pundit lab+ equipment. Comparison of the actual compressive strength and estimated compressive strengths from equations generated for each sample type using the crushed samples on the 7th and 28th days respectively shows that most estimations were within the acceptable ±20% variation. Results show that there is no significant difference between the samples made from using either of the two fine aggregates. Manuscript profile -
Open Access Article
7 - Isogeometric Analysis for Topology Optimisation of Two Dimensional Planar and Laminated Composite Plate Continuum Structures
K.N.V Chandrasekhar V Bhikshma N Rakesh N Swapnareddy C Rakesh -
Open Access Article
8 - Experimental, Franc2d, and DDM simulation to determine the anisotropic tensile strength of brittle material
Vahab Sarfarazi Hadi HaeriIn this paper, a compression-to-tensile load converter device is developed to determine the anisotropic tensile strength of brittle material. A cubic sample with an internal pore was used as the test specimen, and a series of finite element analysis and DDM simulations MoreIn this paper, a compression-to-tensile load converter device is developed to determine the anisotropic tensile strength of brittle material. A cubic sample with an internal pore was used as the test specimen, and a series of finite element analysis and DDM simulations were performed thereafter to analyse the effect of pore dimensions on the stress concentration, as well as to render a suitable criterion for determining the anisotropic tensile strength of concrete. The results obtained by this device show that the tensile strength of concrete is similar in different directions because of the homogeneity of bonding between the materials. Manuscript profile -
Open Access Article
9 - Environmental hazards of construction debris caused by earthquakes on the outskirts of Tehran
Aliasghar Amir KardoustIn the event of an earthquake environmental hazard, reinforced concrete buildings in Tehran, in addition to destroying and inflicting extensive human and financial losses, will lead to the production of construction debris and mass debris. In this study, the reliability MoreIn the event of an earthquake environmental hazard, reinforced concrete buildings in Tehran, in addition to destroying and inflicting extensive human and financial losses, will lead to the production of construction debris and mass debris. In this study, the reliability analysis in 110 concrete buildings running in area one of Tehran with the assumption of variable compressive strength of concrete and yield strength of rebar has been investigated. That is, it has compared the flexural frame and the flexural frame with the shear wall. And this is slightly higher in shear walls. Also, in all tested rebar’s (environmentally friendly), the average yield strength was higher than the nominal strength. Regarding seismic performance, shear wall structure has less general and relative displacement than flexural frame structure. The results of reliability analysis showed that the use of shear wall system instead of bending frame can reduce damage to non-structural components and consequently reduce the production of construction debris and preserve the environment. Manuscript profile -
Open Access Article
10 - Economic (Cost-Benefit) Analysis of Power Generation from Commercial Reinforced Concrete Solar Chimney Power Plant Built in the Desert Regions of Iran
Farhad Saleki Baghban Hosein Nasir Aghdam -
Open Access Article
11 - Examining the Mixing Plan and the Results of the Plastic Concrete
Abolfazl Ostovarzijerdi Akbar Ghanbari Mohammad Karkon -
Open Access Article
12 - Effect of Partial Replacement of Crushed Aggregate with Natural Sand on Mechanical and Rheological Properties of Self-Compacting Concrete
Hamidreza Amini Jamal Ahmadi Behzad Saeedi Razavi Mehdi Babaei -
Open Access Article
13 - Mechanical Properties of Low Strength Concrete Incorporating Carbon Nanotubes
Meysam Morsali Reza Farokhzad -
Open Access Article
14 - Prediction of mechanical and fresh properties of self-consolidating concrete (SCC) using multi-objective genetic algorithm (MOGA)
Reza Jelokhani Niaraki Reza Farokhzad -
Open Access Article
15 - Evaluation of Autogenous Shrinkage in High-Performance Concrete
Jamal Ahmadi Reza Naghdi2 -
Open Access Article
16 - Rheological properties of self-consolidating concrete made by crushed waste tile aggregates
Mahdi Mahdikhani Fatemeh Safikhani -
Open Access Article
17 - NEW RCS Frame Connection in Structures
Hasan Aghabarati K. Parhizkar -
Open Access Article
18 - An Experimental Study on Effect of Waste Tire Rubber on the Fresh and Hardened Behavior of Self-compacting Concrete
Mohammad saleh Moghaddam Saman RahatDahmardeh mohammad hassan Moghaddam -
Open Access Article
19 - The Influence of Pet Fibers on the Properties of Fresh and Hardened Concrete
N Shamskia -
Open Access Article
20 - Effect of Polypropylene Fibers on Strength and Thermal Resistance of Concrete
Jamal Ahmadi Hossein Aghajanloo -
Open Access Article
21 - The New Generation of Concrete with the Approach of Ductility: Review
Javad Chegini -
Open Access Article
22 - Investigation of Stress-Strain Behavior of Plastic Concrete Using Monotonic Triaxial Compression Tests
y. Pashang pisheh seyed majddin Mir mohammad hosseinib -
Open Access Article
23 - Investigating properties of fresh and hardened self-compacting concrete made of recycled aggregates
Pouria Javadi Ali Delnavaz -
Open Access Article
24 - A study on strength and durability of self-compacting concretes made of recycled aggregates
Moslem Mohammadi Jatani Ali Delnavaz -
Open Access Article
25 - The Investigation of Effective Factors in the Removal of Bentonite Jelly from the Joints of Cut-off Wall Panels
Seyed Majdeddin Mir Mohammad Hosseini Abdolhossein Azadmaneshb -
Open Access Article
26 - Developing a Cost-Effective Approach for Enhancing the Rheological and Mechanical Behavior of High Strength Self-Compacting Concrete
Sahand Mardi Morteza Bastami -
Open Access Article
27 - Investigating the Effect of natural Pozzolans on Mechanical Properties of Roller Compacted Concrete
Mohammad Falahnejad Mahdi Mahdikhani -
Open Access Article
28 - Investigation of mechanical and durability properties of lightweight concrete containing Pumice
Amirmohammad Soleimani Seyed Amir Hossein Hashemi -
Open Access Article
29 - Designing a prefabricated sandwich composite roofing system Made up of resisting facings and light-weight concrete core with truss-shaped connectors
Arash Totonchi Allah dad Ahmadi -
Open Access Article
30 - Analysis of Masonry Infill Panels Retrofitted with FRP Sheets in R/C Frames
Hosein Parastesh Murat Saatcioglu -
Open Access Article
31 - The Effect of PVA Fibers and Nano-Particles on the Bonding Strength of Fiber Reinforced Concrete
hossein nematian jelodar Ata Hojatkashani Rahmat Madandoust Abbas Akbarpour Seyed Azim HosseiniAbstract Repairing and Strengthening of concrete structures is of special importance and the mechanical properties of repair mortars and their compatibility with the base concrete are significant aspects in the field of repairing of damaged concrete structures. The bond MoreAbstract Repairing and Strengthening of concrete structures is of special importance and the mechanical properties of repair mortars and their compatibility with the base concrete are significant aspects in the field of repairing of damaged concrete structures. The bond strength parameter of materials is one of the important properties in the selection of repair mortars. In the current Experimental studies, the bond strength of 7 types of cement base mortars consisting Nano-Silica (NS), Micro-Silica (SF) and Polyvinyl Alcohol (PVA) fibers have been tested on base concrete according to ASTM C882 standard. The base concrete is made of fiber concrete with a target compressive strength of 45 MPa and consisting macrosynthetic fibers. The workability of fiber concrete was 120 mm, and the method of curing the samples was done as the wet method. The obtained results indicate that all 7 types of repair materials of this research were compatible with the base concrete and the sample with the combination of PVA fibers and Nano-Silica in cement-based mortars has increased the bond strength of the samples by 85% compared to the samples without fibers. The highest bond strength among the samples was related to cement based mortar containing PVA fibers and Nano-silica (PVA0.75NS6) with bond strength equal to 21.83 MPa. Manuscript profile -
Open Access Article
32 - Investigation of effective parameters on compressive strength, specific electrical resistance and water absorption of lightweight pervious concrete
Shahriar GholaminNoveirsar Morteza Jamshidi Rahmat MadandoustPervious concrete is a special type of lightweight concrete with low or even zero slump, which consists of cement, coarse aggregate, a limited percentage of fine aggregate (or no fine aggregate), various chemical and pozzolanic additives. In this article, structural LEC MorePervious concrete is a special type of lightweight concrete with low or even zero slump, which consists of cement, coarse aggregate, a limited percentage of fine aggregate (or no fine aggregate), various chemical and pozzolanic additives. In this article, structural LECA with a volumetric weight of 750 kg/m3 and a fixed water-to-cement ratio (W/C = 0.3) was used to make lightweight pervious concrete and the effect of different ratios of lightweight aggregate to cement (A/C) including 1.5, 1.8, 2.1, 2.4, 2.7, 3, total porosity and volume percentage of cement paste on compressive strength , specific electrical resistance and percentage of water absorption of lightweight pervious concrete aged 28 days were investigated. With the increase of A/C ratio from 1.5 to 3, the volume of cement paste decreased from 30.873% to 15.436% in the samples and the total porosity increased from 21.64% to 38.08%, which led to a decrease Specific electrical resistance decreased from 11.45 to 6.841 , compressive strength decreased from 13.27 MPa to 4.37 MPa, and water absorption increased from 11.185% to 12.695% in lightweight pervious concrete samples. The results of this research showed the improvement of physical properties and the decrease of mechanical properties and durability of lightweight pervious concrete containing LECA. Manuscript profile -
Open Access Article
33 - Friction damper optimization based on parallel sensitivity analysis For self-centering concrete walls with gravity columns
mohsen izadinia mahdi ravanbakhshian Hosein Tajmir Mohammadhasan MeisamiIn recent years, self-centering concrete walls have been used as modern structures. The mechanism of these structures is such that the focus of energy dissipation is on the dampers, and the role of the concrete wall and tendons is to create stiffness and provide the sel MoreIn recent years, self-centering concrete walls have been used as modern structures. The mechanism of these structures is such that the focus of energy dissipation is on the dampers, and the role of the concrete wall and tendons is to create stiffness and provide the self-centering capacity in the system. in a way that reduces the residual deformation in the system. The most important point that should be considered in these structures is the optimal use of dampers in them. In this article, a new system has been introduced which is a combination of self-centering concrete walls with gravity columns. in such a way that the friction dampers were placed in the middle and side positions of the concrete wall. The main focus and goal of this research is to investigate the optimal numerical value for the "slip load of friction dampers" in the middle and side positions of the Self-centering concrete wall based on the "amount of prestressing force" in the friction screws of the dampers, as in the current study , the resistance of damper materials, their shape and dimensional size are not considered as variable parameters And in determining the optimal damping, they are considered without influence.In total, the optimal sliding load based on the tensioning force in the friction bolts has been simultaneously determined by two-way sensitivity analysis by OpenSEES software. Manuscript profile -
Open Access Article
34 - Evaluation of Nonlinear Seismic Behavior of Reinforced Concrete moment Frames with Special Ductility with and without Viscous Dampers on the Floors Level
ashkan khodabandehlou siamak barmakiThe main goal of this research is to evaluate the nonlinear seismic behavior of special RC moment with and without viscous dampers at the floor level. In this research, 2 high-rise three-dimensional RC building frames of 12 and 16 stories, each frame with 8 models, 4 mo MoreThe main goal of this research is to evaluate the nonlinear seismic behavior of special RC moment with and without viscous dampers at the floor level. In this research, 2 high-rise three-dimensional RC building frames of 12 and 16 stories, each frame with 8 models, 4 models with and 4 models without viscous damper at the floor level, located in the area with High seismicity on type 3 soil is considered. In order to seismic analysis of frames with and without viscous dampers, nonlinear static analysis method was used according to the second appendix of Iran earthquake regulations, fourth edition. The initial dimensions of the structural elements of the studied frames and the thickness of the roof slabs have been determined in ETABS-V15 and SAFE2014 software, respectively, and finally, modeling, gravity and lateral loading, and nonlinear static analysis of the studied frames have been performed in the SAP2000-V19 software. The results show that the change in the sections of beams and columns from square to rectangle in frames with and without viscous damper causes an increase in the relative lateral displacement of the floors, as well as an increase in the number of openings along the Y axis (model 1 compared to 3), and an increase in the length of the opening along the Y axis (model 1 Compared to 4), in frames with and without viscous damper, it reduces the absolute lateral displacement of floors. Manuscript profile -
Open Access Article
35 - The Experimental Study of the Influence of Function and Arrangement of Geogrids and Uniform Stress Distribution in the Tensile Area of the Concrete structures
Ashkan khodaBandeLou aliasgar akbari bargoshadiConcrete is one of the main materials used in the construction industry and there are disadvantages to the conventional method of using steel, which reduces the breakage and concrete failure. Today, the spread of the science of applying polymeric materials to overcome t MoreConcrete is one of the main materials used in the construction industry and there are disadvantages to the conventional method of using steel, which reduces the breakage and concrete failure. Today, the spread of the science of applying polymeric materials to overcome these disadvantages has quickly taken its place in concrete ingredients. These materials can produce stronger concrete with greater flexibility and a smoother surface and can increase concrete resistance to erosion, impact and corrosion. In this research, using Geogrid, which is a family of geosynthetics, the tensile strength of concrete increased by 15%. Because it is used as a solid with very low risk, the geogrid is placed at different distances from the neutral warp. Based on the results of the experiments and according to the diagrams obtained from the geogrid experiments, if utilized as a semi-solid in the tensile region, the geogrids will result in the equal distribution of stresses and will have a better effect on increasing tensile strength. Of course, using a combination of steel and geogrid in the tensile region and according to the geogrid characteristics, it is easier to achieve a soft failure (tensile failure), which is the best type of failure for concrete structures. Manuscript profile -
Open Access Article
36 - Calculation of the Behavior Coefficient of the Combined System of Special Moment-resisting Frame and Concrete Shear Wall with Openings Reinforced with CFRP
Seyed Fathollah Sajedi Mostafa Echresh AmiriToday, the reinforcing polymer composites are widely applied to improve the seismic behavior of the structures. The history of structures reinforced with polymer sheets is mostly related to the reinforcement of beams and columns. In this study, the behavior coefficient MoreToday, the reinforcing polymer composites are widely applied to improve the seismic behavior of the structures. The history of structures reinforced with polymer sheets is mostly related to the reinforcement of beams and columns. In this study, the behavior coefficient of a special concrete moment-resisting frame in combination with a concrete shear wall (CSW) with opening and retrofitted with Carbon fiber reinforced polymer (CFRP) was calculated. The CSW was added as a reinforcement to the pre-designed concrete moment-resisting frame at two heights of 8 and 12 floors, then circular, rhombic and rectangular openings were created in the walls and CFRP were added around the openings along 45 and 90 degrees on one side and both sides of the wall. The results of the analyses presented that the strength of the structure decreased with the opening of the wall, and when the fibers were added around the opening, the resistance increased slightly; this slight increase in strength is due to the low amount of fibers. To cope with this issue, a layer of fibers was glued to the wall area on one side, on both sides, and two layers of fibers on one side of the wall around the opening. The interpretation of the results indicated that the higher the level of reinforcing fibers on the wall, the higher the capacity and behavior coefficient of the structure. The addition of CFRP on both sides of the wall had a better effect on the behavior coefficient and capacity of the structure than the application of two layers of fibers on one side of the wall. Manuscript profile -
Open Access Article
37 - Investigating the Effects of Using Microsilica and Nanosilica on the Hardened Mechanical Properties and Durability of SCC Containing Recycled Aggregates
Reza Farokhzad mohsen mehrpoya Today, the wastes remaining from concrete degradation is considered as an environmental problem and is one of the biggest challenges in the building industry. Accordingly, many researchers have decided to re-use the materials of aggregates from More Today, the wastes remaining from concrete degradation is considered as an environmental problem and is one of the biggest challenges in the building industry. Accordingly, many researchers have decided to re-use the materials of aggregates from degradation in concrete production cycles. In this paper, attempts were made to assess and if possible to promote the mechanical and durability characteristics after the addition of nano-silica and micro-silica to self-compacting concrete containing recycled aggregates (obtained from worn concrete degradation). One of the points to be considered in this paper was the attempt to use tests such as half-pole testing and concrete wave velocity. In this regard, 72 mixture designs were studied in 8 collections. In these mixture designs, with respect to the content of recycled aggregates, the nano- and micro-contents were changed. Then, the samples underwent mechanical tests including compressive strength and tensile strength, and durability tests including corrosion potential, concrete wave velocity (ultrasonic) and electrical strength. After the tests, with an increase in the use of nano-silica and micro-silica, the efficiency and fluidity of the fresh concrete were reduced, and compressive strength and tensile strength were increased. Also, at fixed strength, nano-silica caused less efficiency and fluidity than micro-silica and also, with an increase in the content of recycled aggregates in concrete, efficiency and fluidity as well as compressive strength and tensile strength of concrete were reduced. Manuscript profile -
Open Access Article
38 - Determining an Efficient Approach for Compound Curing of High Resistant Concretes under Saturated / Autoclave Medium and Studying the Influence of Saturated Situation on Reduction of Holdinng Time in Autoclave
houman sharabiani fereydon zeynaliIn order to determine an efficient approach for compound curing of high resistant concertes under saturated/ autoclave medium and studying the influence of saturated situation on reduction of holding time in autoclave, the research was carried out using different curing MoreIn order to determine an efficient approach for compound curing of high resistant concertes under saturated/ autoclave medium and studying the influence of saturated situation on reduction of holding time in autoclave, the research was carried out using different curing methods. Concrete specimens which were prepared on standard methods were divided into control and treated ones from which the formers were just exposed to saturated situation(which attained compressive strength of 884.54 Kg/cm2 at 28 days) while the other 3 sets were cured as follows: First and second part were placed under saturated situation for one to three days but the remaining one) was directly transferred to autoclave. All of these 3 sets were maintained in autoclave for 15 to 150 minutes. Results showed that specimens kept in autoclave for 15 minutes (without any maintenance at saturated situation), attained compressive strength of 748.73 Kg/cm2 while in the case of the ones kept at saturated situation for one-day (before autoclave) the compressive strength to 834.71 Kg/cm2 which was about 84.65 and 94.37% of compressive strength of the control sample at the age of 28-days respectively. By increasing the autoclave time to 30 minutes, the compressive strength of the specimens under two circumstances mentioned above improved up to 892.40 Kg/cm2 and 903.51 Kg/cm2 respectively which was about the compressive strength of the check specimen in 28 days. We found no impact on compressive strength growth whenever samples were kept in autoclave for more then one-day Manuscript profile -
Open Access Article
39 - Investigation of Seismic Behavior of Concrete Structures Reinforced with FRP and Steel Bars
arash dalili ramin vafaeipoorConsidering the increasing use of FRP bars, as reinforcement in concrete structures, the study of the dynamic behavior of these types of structures and its behavioral comparison with steel reinforced concrete structures seem to be necessary. In this regard, in the prese MoreConsidering the increasing use of FRP bars, as reinforcement in concrete structures, the study of the dynamic behavior of these types of structures and its behavioral comparison with steel reinforced concrete structures seem to be necessary. In this regard, in the present study, buildings with floors 2, 5, and 10 in two-dimensional and three-dimensional states were considered in two types of steel reinforced and FRP reinforced were modeled and analyzed in ABAQUS software. By using the results of the analysis, behavioral comparisons between these structures were carried out with a focus on displacement. By considering in the same conditions, the results of the analysis reveal that displacement in FRP-reinforced structures is more than steel-reinforced structures. Also, in the 2-storey building model, the relation between steel structures and FRP structures is linear with 90% regression coefficient was observed while in 5-storey buildings and 10-storey building’s behavior are nonlinear, with a regression coefficient of 89% and 87%, respectively. Manuscript profile -
Open Access Article
40 - Friction damper optimization based on parallel sensitivity analysis for self-centering concrete walls with gravity columns
mahdi ravanbakhshian mohsen izadinia Hosein Tajmir Mohammadhasan MeisamiIn recent years, self-centering concrete walls have been utilized as modern structures. The mechanism of these structures is such that the focus of energy dissipation is on the dampers, and the role of the concrete wall and tendons is to create stiffness and provide the MoreIn recent years, self-centering concrete walls have been utilized as modern structures. The mechanism of these structures is such that the focus of energy dissipation is on the dampers, and the role of the concrete wall and tendons is to create stiffness and provide the self-centering capacity in the system resulted in the reduction of residual deformation in the system. The jointed self-centering concrete walls are a type of self-centering wall system where dampers are placed between two concrete wall panels. The most important point that should be considered in these structures is the optimal use of dampers in them. In the present research, a new system has been introduced, which is a combination of self-centering concrete walls with gravity columns. In such a way that the friction dampers were placed in the middle and side positions of the concrete wall. This research aimed to investigate the optimal numerical value for the "slip load of friction dampers" in the middle and side positions of the Self-centering concrete wall based on the "amount of prestressing force" in the friction screws of the dampers. In the current study, the resistance of damper materials, their shape and dimensional size are not considered as variable parameters and they are considered without influence in determining the optimal damping. In total, the optimal sliding load based on the prestressing force in the friction bolts has been simultaneously determined by two-way sensitivity analysis by OpenSEES software. Based on the results, applying the method of determining the percentage of the minimum response coefficient (R) based on parallel (two-way) sensitivity analysis can be recognized as a very efficient method for determining the most optimal friction damper in Self-centering jointed concrete wall systems. Furthermore, the prestressed and optimal force for the dampers indicated that the dampers located between the two walls (set of middle dampers) exhibit a specific optimal value and other dampers (set of side dampers) also present a different optimal value. Manuscript profile -
Open Access Article
41 - Experimental study of modulus of elasticity of Alkali-activated concrete based on XRF and SEM tests
Mohammadhossein Mansourghanaei Morteza Biklaryan Alireza MardookhpourIn this research, firstly, three mix designs of alkali-activated concrete containing 92, 96, and 100% blast furnace slag and 8, 4, and 0% nano-silica were made. After performing the compressive strength and modulus of elasticity tests and choosing one design as the opti MoreIn this research, firstly, three mix designs of alkali-activated concrete containing 92, 96, and 100% blast furnace slag and 8, 4, and 0% nano-silica were made. After performing the compressive strength and modulus of elasticity tests and choosing one design as the optimal design in terms of superior mechanical properties, by adding 1 and 2% polyolefin fibers to the optimal design, two more designs of alkali-activated concrete were made. All concrete samples were subjected to compressive strength and modulus of elasticity, XRF and SEM tests. The results of the tests exhibited superiority in mechanical and microstructural properties of the alkali-activated concrete compared to normal concrete at all processing ages. At the processing age of 90 days (as the best age in performance due to the progress of the chemical process), following the compressive strength test, the lowest (49.94 MPa) and the highest (66.36 MPa) compressive strength values were obtained, respectively, for design 1 including Normal concrete and design 4 including alkai-activated concrete containing 8% nanosilica. At the same processing age, the lowest (32.44 GPa) and the highest (42.51 GPa) modulus of elasticity were achieved in design 1 and 6 of the alkali-activated concrete containing 8% nano-silica and 2% polyolefin fibers, respectively. At this age, addition of 8% nano-silica and 2% fibers in the alkali-activated concrete of design 6 resulted in a decrease of 22.49% in the compressive strength and an improvement of 7.05% in the modulus of elasticity. Manuscript profile -
Open Access Article
42 - Long term and short term effect of zeolite on tensile and pressure strenght of semi light weight concrete with local materials of sistan and baluchestan
Adel Rezai Reza rahgozarLight weight construction is one of modern topics in civil engineering, the topic of reducing weight of structure is achiev by use of new technique and optimization of construction procedure. Consideration to wide use of concrete and enviromental pollu MoreLight weight construction is one of modern topics in civil engineering, the topic of reducing weight of structure is achiev by use of new technique and optimization of construction procedure. Consideration to wide use of concrete and enviromental pollution to the reason of using cement, investigators are trying to replace a part of cement by natural and artifitial pozzolan and nano particle materials. In this study the use of natural pozzolan zeolite with different percents 0, 5, 10, 15, 20 investigated and longterm and short term effects on the compression and tensile strenght on semi light weight concrete at the age 3, 56, 90 days were studied and compared with control specimen. Result shows that 5% and 10% replacement of zeolite improve compression strength at the age of 3, 90 days, and for age of 56 days most improvement is related to 15% replacement by zeolite. Manuscript profile -
Open Access Article
43 - On the influence of age on compressive strength of UHPCs constructed in Iran
masood pourbaba elyar asefiThe mix design of the Ultra-High-Performance Concrete (UHPC) consists of water, microsilica, steel fiber, cement, fine sand, superplasticizer and stone powders such as quartz. The intended UHPC will be constructed using the indigenous materials in Iran which will be sub MoreThe mix design of the Ultra-High-Performance Concrete (UHPC) consists of water, microsilica, steel fiber, cement, fine sand, superplasticizer and stone powders such as quartz. The intended UHPC will be constructed using the indigenous materials in Iran which will be subject to investigations regarding the influence of ageing on its compressive strength. Low water-to-cement ratios contribute to high-density concretes exceeding 130MPa in compressive strength. Incorporation of the steel fiber plays its role in enhancing the tensile strength and post-cracking behavior of concrete by bridging and closing the cracks from their initiation until their propagation. Attention should also be given to the application of the highly-reactive microsilica with its high surface energy feature should. In this study, 112 cubic specimens (10 with different steel fiber contents were investigated. Compressive strength tests were carried out on concrete during different stages of ageing. Results revealed an increasing trend for the compressive strength of concrete with the increase in fiber content (5). However, there is an upper limit for the fiber content, e.g. 6% which significantly degrades the performance of concrete beyond this limit, not to mention the challenges that occur in practice in this case. Finally, for specimens constructed with the aforementioned procedure, 90% of the ultimate strengths are obtained after 18 days. Manuscript profile -
Open Access Article
44 - Experimental investigation on Quartz Powder effect on Compressive Strengths of High Strength Concrete (HSC)
javad javadi Masoud PourbabaHSC has great mechanical properties and durability and is one of technology developments in concrete. This type of concrete has high cohesion, compressive strength and low water to cement ratio and permeability which results to high durability. HSC is a cemental composi MoreHSC has great mechanical properties and durability and is one of technology developments in concrete. This type of concrete has high cohesion, compressive strength and low water to cement ratio and permeability which results to high durability. HSC is a cemental composite product that contains optimum amount of fines and with a water to cement ratio (W/C) less than 0.25.High performance concrete compared with normal concrete has a structure with discontinous pores that results to high performance and minimum water permeation to concrete. HSC’s admixture contains water, silica fume, cement, fine sand, super plastisizer and rock powder like quartz that in this study are used of Iran’s local materials. In this study 10x10x10 cube specimens were made and evaluated. Compressive leads to failure were applied to concrete specimens. The purpose of this study is investigation of quartz powders increase in HSC.Results shows that concrete compressive strength with 11% quartz powder is the highest and increase in quartz powder lead to brittle pre failure and explossive failure of concrete specimens.Other considerations shows that increase of quartz powder leads to more crack on concrete and it is suggested to use fibers to prevent more crack in this type of concretes. Manuscript profile -
Open Access Article
45 - Investigation of the effects of high temperature on compressive and tensile strength and modulus of elasticity of alkali-activated concrete
Mohammadhossein MansourghanaeiIn recent years, improving the mechanical properties of alkali- activated concrete with the aim of being superior compared to those of the conventional concrete and reducing environmental hazards caused by the lack of mineral resources and release of toxic carbon dioxid MoreIn recent years, improving the mechanical properties of alkali- activated concrete with the aim of being superior compared to those of the conventional concrete and reducing environmental hazards caused by the lack of mineral resources and release of toxic carbon dioxide gas (in cement production process) has been noticed by civil engineering researchers. In this laboratory research, a mixing design of ordinary concrete containing Portland cement with a grade of 500 kg/m3 and a mixing design of alkali-activated concrete based on blast furnace slag were made. In order to check the mechanical properties, tests of compressive strength, tensile strength and modulus of elasticity of concrete were performed under the temperatures of 21 and 600 ℃ at the age of 90 days of curing. Based on the results, applying high temperature (600 ℃) to concrete samples caused a 42% and 15% drop in compressive strength, a 56% and 21% drop in tensile strength, and a 63% and 49% drop in modulus of elasticity for ordinary and alkali-activated concretes, respectively. The compressive strength of alkali-activated concrete was 11% and 64% more than that of the normal concrete at 21 and 600 ℃, respectively. The tensile strength of alkali-activated concrete exhibited a 9% decrease and 63% superiority compared to normal concrete at 21 and 600 ℃, respectively. The elasticity modulus of alkali-activated concrete was 16% and 62% higher than that of the normal concrete at 21 and 600 ℃, respectively. The results of the scanning electron microscope images are in accordance with the other test results of this research. Manuscript profile -
Open Access Article
46 - Investigation of flexural strength of ultra-high performance concrete reinforced with steel fibers using multiscale finite element model
Amir ebrahim akbari bagal Ahmad maleki ramin vafaeipoorThe main purpose of this study is to develop a finite element model to study the effect of steel-shaped fibers on the flexural strength of ultra-high performance fiber concrete. For this purpose, in order to numerically simulate, a multi-scale finite element model was d MoreThe main purpose of this study is to develop a finite element model to study the effect of steel-shaped fibers on the flexural strength of ultra-high performance fiber concrete. For this purpose, in order to numerically simulate, a multi-scale finite element model was developed in which concrete was modeled as a homogeneous and uniform material and steel fibers were randomly distributed inside it. In order to make more realistic assumptions, the area of adhesion between the fibers and the concrete is also considered. After validating the results of finite element model with the results of experimental tests, the effect of parameters such as volume fraction and adhesion of steel fibers on the strength characteristics of flexural strength of ultra-high performance concrete reinforced with fibers has been studied numerically. The results indicate that the effect of using fibers on the amount of energy absorption by fiber reinforced concrete is much greater than its effect on other characteristics of this type of concrete and especially the use of fibers in low fiber volumes has a very significant effect on energy absorption so that for 0.5% of the volume fraction of steel fibers, an increase of about 17 times compared to the sample of super-reinforced concrete without fibers can be resulted Manuscript profile -
Open Access Article
47 - Investigation of mechanical properties and effects oftypicalaggregates in preparation of pervious concrete
Majid Rostami eman Bahramiperviousconcrete is a special kind of concrete which has a high degree of porosity and one of its major applications is in the roadway pavements. Todays, due to transportation importance, using of new materials in land, sea, airand railway transportation infrastructures Moreperviousconcrete is a special kind of concrete which has a high degree of porosity and one of its major applications is in the roadway pavements. Todays, due to transportation importance, using of new materials in land, sea, airand railway transportation infrastructures is among hot research topic. Pervious concrete is one kindof the rigid pavement which has great advantages include; high permeability, proper hydraulic conduction, surface water filtration and to the underground water sourcesinjection. Despite having many advantages, its low compressive strength is one of its disadvantageswhich indicate demands for deeperstudies to increase the compressive strength of this type of concrete. In this research, a series of experimentaltestsis done on typical aggregate samples with different material and graduation, in first step their physical and specious properties was examined and then after preparation of different mix designs for making perviousconcrete sample, properties of obtained concrete samples like: permeability, porosity, and compressive strength were investigated, after that, conducting the tests on various specimens, the results were analyzed. Finally, based on the results and analyses of the conducted tests, the optimum mix designs were introduced based on their application. Manuscript profile -
Open Access Article
48 - Investigation of the effective factors for eliminating the defect in the CFT columns with an asymmetric L-shaped columns by the finite element Analysis
seyed ali mousavi davoudi morteza naghipourThe use of CFT-filled steel columns is increasing worldwide due to the proper co-operation of concrete and steel, with more concrete steel columns being implemented in circular shapes, which is due to the fact that the core concrete is more enclosed with the circular cr MoreThe use of CFT-filled steel columns is increasing worldwide due to the proper co-operation of concrete and steel, with more concrete steel columns being implemented in circular shapes, which is due to the fact that the core concrete is more enclosed with the circular cross-sections, but sometimes it is impossible to use symmetrical cross sections and other forms such as L-shaped crosses are used, which create less confinement for the core because of their asymmetry. This issue decreases the bearing capacity on these columns formed by an asymmetric L-section. The aim of this study was to study the asymmetric L-shaped cross-section of steel-filled concrete columns in order to provide the reduction of confinement due to effective parameters such as height, steel cross-section thickness and compressive stress. In this investigation, steel wall thickness, height, and compressive strength of concrete on the effect of securing core concrete confinement in L-shaped sections under finite element analysis were observed that the effect of steel wall thickness (t) in L-shaped cross-sections is one of the most effective parameters to remove the confinement defect that the impact of this effect is, on average, about 18.31% more higher than the parameters of height and compressive strength of concrete. Finally, it was concluded that the asymmetric L-shaped sections would be more confined by changing the thickness of the steel wall compared to the concrete compressive strength and height parameter. Manuscript profile -
Open Access Article
49 - Estimation of Response Modification Factor of Precast Concrete Frames with Semi Rigid Connections strengthened with X-Steel Bracing
Babak Behforouz Mohammadhasan Meisami zahrasadat mousaviAs the population grows, the importance of creating more buildings in the short term and at low cost, such as prefabricated structures, becomes more apparent. For this purpose, in this research using SAP 2000-14 software, three kinds of 2, 4 and 6-story RC frames were d MoreAs the population grows, the importance of creating more buildings in the short term and at low cost, such as prefabricated structures, becomes more apparent. For this purpose, in this research using SAP 2000-14 software, three kinds of 2, 4 and 6-story RC frames were designed by considering connection rigidity. Three types of connection rigidity including pinned, semi-rigid and rigid precast RC connections were applied to estimate response modification factor (R) of designed frames. It is worth mentioning that each of the frames has five bays and the length of each of the bays is 5 meters with the exception of median bay that is 4 meters strengthened with X-steel bracing. Then the nonlinear static analysis was applied to evaluate the effect of frame’s height and connection rigidity on response modification factor of designed frames. The results presented that with increasing the rigidity and frame’s height R factor is increased. Manuscript profile -
Open Access Article
50 - The study of mechanical behavior of composite steel columns filled with concrete with cross-section (T) shape under numerical sensitivity analysis of finite element under axial load
seyed ali mousavi davoudi morteza naghipourConcrete Filled Tube (CFT) steel columns have become increasingly popular in recent years due to their many advantages in industrial and high-rise buildings, bridges, piers and piles. These columns often run in circular shapes. The main reason for this is that circular MoreConcrete Filled Tube (CFT) steel columns have become increasingly popular in recent years due to their many advantages in industrial and high-rise buildings, bridges, piers and piles. These columns often run in circular shapes. The main reason for this is that circular sections create more confinement than other sections in core concrete. This caused the circular sections to be used more frequently in the CFT columns than other sections. But sometimes it will be impossible to use circular sections and will have to use special forms, such as square and mesial sections, and L and T-shaped sections in some parts of the building. Due to the importance of this issue in this paper, we tried to introduce and investigate the mechanical behavior of CFT columns with T-shaped geometrical cross section and to investigate the parametric effect of steel wall thickness, and concrete compressive stress, on the mechanical capacity and behavior of these columns. Finally, after conducting the research, it was found that in CFT columns with T-geometrical cross section, between the effect of steel wall thickness and the type of concrete, the steel wall thickness parameter is the most influential parameter on the bearing capacity of the CFT columns, and also between the steel wall thickness parameter and the cross section height, Influence of elevation changes on ductility, hardness, and bearing capacity of the cross section It is greater than the thickness of the steel wall. Manuscript profile -
Open Access Article
51 - An investigation into the properties of concrete made from concrete debris and effects of the three-step mixing procedure on it
Mohammad Khazaei Abdolkarim Abbasi DezfouliUsing by-product materials in making concrete is the recent development in the advanced concrete technology. The products obtained from experimental crushed concrete can be used in constructing the new concrete. Recent research revealed that using crushed concrete as pa MoreUsing by-product materials in making concrete is the recent development in the advanced concrete technology. The products obtained from experimental crushed concrete can be used in constructing the new concrete. Recent research revealed that using crushed concrete as partial replacement of sand and coarse aggregate, using traditional mixing procedure, reduced the compressive strength. In the present research, the special procedure of mixing concrete in three steps and its effect on concrete strength parameters have been evaluated. The aim of this study is to use crushed tested concrete as partial replacement 25% (mix A) and 50% (mix B) of conventional sand and aggregate. Also for experimental comparison the control mixes were casted with traditional sand and aggregate. Superplasticizer based on carboxylate was used in the mixes. This procedure causes proper efficiency, proper coating on the aggregate and protection of the alkaline reaction of the aggregate. The method of mixing was carried out in three steps 1: Coarse aggregate + 50% water + 50% cement: mixing time 30 seconds to 1 minute, step 2: Adding 50% cement + 25% water + superplasticizer + sand: mixing time 2 minutes, step 3: Adding 25% water: mixing time 3 minutes. All the mixing time is about 6 minutes. Six specimens of 15 cm concrete cubes for each designed mixes were casted. Densities, water absorption, electric resistance (an indication of permeability and durability of concrete) and compressive strength tests were carried out. Tests were performed at 7 and 28 days. As a result, the designed mix (A) presented the higher electric resistance and compressive strength at 28 days. According to the obtained appropriate resistance, it can be deduced that with a special mixing method, crushed concrete can be used in the composition of concrete that is cost-effective in terms of environmental and resistance. Manuscript profile -
Open Access Article
52 - A Study on the Flexural-Shear Behavior of Concrete Beams and Comparison of the Experimental Test Results with the Prediction of Different Codes
yousof Abbasi Parvin Taleb Moradi Shaghaghi Masoud pourbaba saeed mirrezaei yousof zandi In this research, a laboratory study was performed on the shear and flexural behavior of single-reinforced concrete (RC)­ beams without stirrups. For this purpose, four single-reinforced concrete beams with the dimensions of 250 by 300 mm and 1650 mm length an More In this research, a laboratory study was performed on the shear and flexural behavior of single-reinforced concrete (RC)­ beams without stirrups. For this purpose, four single-reinforced concrete beams with the dimensions of 250 by 300 mm and 1650 mm length and in four longitudinal reinforcement steel bars’ percentages of 0.36, 0.64, 1.05 and 1.45 of conventional rebars (S400) and concrete with compressive strength in the range of 35 Mpa were designed and all specimens were tested under four-point bending test. The test results presented that increasing of the reinforcement ratio of tensile rebars was efficient in increasing of the shear capacity of beams. Then, the shear and flexural strength obtained from the test were compared with the final shear and flexural strength predicted using AS3600, ACI, JSCE, EN, CSA, NZA , Iran codes and the proposed relationship by Al-Taan, and Al-Feel. The studies indicated the accuracy of the relationships proposed by Al-Taan and Al-Feel with an average of 1.26 times less than the experimental results, and the large difference between the values proposed by the Iranian Concrete Code and Japan (JSCE) Code with an average of 2.29 and 2.35 times, respectively less than the shear strength obtained from the test results, compared to other regulations in this research. In other words, they take a greater margin of confidence into account Manuscript profile -
Open Access Article
53 - Reviewing Optimal Percent of Steel Fibers and their Effects on Lightweight Concrete Durability
Ali Ghods sanaz chahkandi Homayon navayiAbstract In recent years, many researches are focused on optimizing the production of a kind of concrete with high strength and efficiency, and different methods including using fiber technology in concrete construction are proposed to achieve this goal. Fibers are one MoreAbstract In recent years, many researches are focused on optimizing the production of a kind of concrete with high strength and efficiency, and different methods including using fiber technology in concrete construction are proposed to achieve this goal. Fibers are one of the materials that nowadays are added to concrete as reinforcement material. Considering the low weight and good resistance of this material and using a good percent of these materials in lightweight concrete can result in smaller segments with greater resistance. In this paper, we try to study and evaluate the effects of steel fibers on the strength and also the amount of fibers in lightweight concrete. One of the strength experiments is wetting and drying which is used in this study. Also by reviewing dynamic properties of lightweight concrete made with pumice + leca and taftan and comparing with lightweight concrete which is armed with steel fiber, we can achieve the optimal percent of fiber in concrete. Experimental results are presented in graphs and charts. Manuscript profile -
Open Access Article
54 - Hysteretic Behavior of Concrete Connections Strengthened by X-Shape FRP Strips
mohammadreza shokrzadeh Armin ََAziminejhad Abdolreza sarvghadmoghaddamDifferent methods may be used for strengthening weak concrete connections.Because of the unique characteristics of FRP composites, they are widely used for strengthening concrete moment resisting frames. These retrofitting techniques are widely considered in research an MoreDifferent methods may be used for strengthening weak concrete connections.Because of the unique characteristics of FRP composites, they are widely used for strengthening concrete moment resisting frames. These retrofitting techniques are widely considered in research and practical applications. The retrofitting cost is an important factor in the selection of the most suitable retrofitting techniques. In the application of FRP laminates, the cost of retrofitting is mainly the function of FRP volume and the surface preparation. In this research, using ABAQUSgeneral purpose finite element software, the effect of different FRP configuration in X-shape connection strengthening scheme were considered and the results were compared with full FRP coverage of connection. In this strengthening scheme, the effect of parameters such as strip width and thickness was examined. The results showed that in strengthening with x-shape strips, the connection could develop the capacity of connection strengthened by full FRP coverage, while it needs about 16 percent less FRP laminates, which meaningfully could reduce the price of connection strengthening. Manuscript profile -
Open Access Article
55 - Investigation of the shear and torsional capacity and confinement of rectangular reinforced concrete beams with spiral stirrups
hamed sefidian ashkan khodabandelouIn general, reinforced concrete elements tend to be very crisp, and this phenomenon is most evident when shaken. One of the advantageous of concrete enclosure is the increased concrete strength and concrete ductility which, if the concrete is properly enclosed and the s MoreIn general, reinforced concrete elements tend to be very crisp, and this phenomenon is most evident when shaken. One of the advantageous of concrete enclosure is the increased concrete strength and concrete ductility which, if the concrete is properly enclosed and the seismic forces cause the concrete to be drilled, the enclosed concrete will resist well. The best way to do this is to use spiral stirrup. In this study, the effect of spiral with regard to the step variables of the spiral and the angle of the bolts on the shear and torsional capacity of rectangular reinforced concrete beams is investigated. ABAQUS finite element software was applied to simulate the samples. The results showed that the angle of cracks created in the specimens with closed stirrup was greater than that of the corresponding specimen (equal distance between the bends and the closed stirrup) with the spiral, and the use of stirrups both in the closed and in the bends situation, have increased the shear and torsional capacity of reinforced concrete beams. This research presented that reinforced concrete beams containing spiral stirrups had greater shear and torsional capacity than those of equipped with the closed stirrups. The use of closed stirrup and spiral stirrup with a step spacing of 80 mm have increased the shear capacity of reinforced concrete beams by 52% and 59%, respectively, which is a significant difference , and the shear and torsional capacity of reinforced concrete beams decrease with increasing step distance. By increasing the distance between the turns from 80 mm to 150 mm, the shear capacity of reinforced concrete beams is reduced by 30%, which is a significant amount. According to the results, the optimum spiral angle that best fits the rectangular reinforced concrete beams is 80 degrees. In this case, the angles of the diagonal cracks are lower than the other cases, and its shear and torsional capacities are significantly greater than the other specimens with equal steps and different angles. Manuscript profile -
Open Access Article
56 - Evaluation of self-compacting concrete and ordinary concrete, by core method, in deep foundations
nobakht bakhtyari jamshid esmaili mehdi AmriSitu concrete piles, are the most widely used type of deep foundation. In Iran experience shows, that technical problems and economic performance by avoiding the use of ordinary concrete with a slump an extremely high in these types of candles. Poor and low compress res MoreSitu concrete piles, are the most widely used type of deep foundation. In Iran experience shows, that technical problems and economic performance by avoiding the use of ordinary concrete with a slump an extremely high in these types of candles. Poor and low compress resistance, durability and high water permeability in the subsurface environment, the effects of this type of concrete planning. The excellent strength, permeability to ensure proper compaction, concrete ease and speed up the planning run, the significant advantages of self-compacting concrete. These benefits are especially situ concrete pile planning, most appear to be. In This paper compares core strength situ by taking samples from two typical arrangement of pile ordinary and self-compacting concrete and important results have been obtained. The core samples, to a depth of 14 m in which different levels of ground benchmark are tested show that the use of self-compacting concrete has technical and economical advantages, and notable administrative lead to greater uniformity in resistance acquisition, located in the upper part of the pile is. This section, the maximum stresses due to vertical and lateral loads. Therefore, the use of self-compacting concrete in deep foundations, can widely replace traditional methods. Manuscript profile -
Open Access Article
57 - Effect of Different Fibers and Pozzolanic Materials on the Properties of non - structural Concrete(Foam Concrete)
Mahyar Kaveh Reza FarokhzadFoam concrete is new cover for several usages in building industry that is very useful because of its unique specification. The high value of strength to weight ratio, low Thermal conductivity Coefficient and the high Heat insulation and soundproof ability is the most a MoreFoam concrete is new cover for several usages in building industry that is very useful because of its unique specification. The high value of strength to weight ratio, low Thermal conductivity Coefficient and the high Heat insulation and soundproof ability is the most advantage of this type concrete. In this investigation we use Polypropylene fibers, Synthetic fibers, rice husk ash and nano silica to improve the foam concrete abilities. The fibers are used as additive and rice husk ash & nano silica are replaced as cement. The compressive strength test, tensile strength test and lentgh change test are performed on all foam concretes. Maximum compressive strength belongs to designs containing 1% synthetic fibers and 1% nano-silica. Finally, it was determined that rice paddy ash in 5% replacement has a 9% increase in compressive strength of 28 days and a 17% increase in tensile strength of 28 days. Compressive strength is not affected by Polypropylene fibers in 0.1% and 0.2%, and in 0.3%, compressive strength decreases. Adding 1% of synthetic fiber to concrete foam has 17% growth in compressive strength and 75% growth in tensile strength. Adding 1% nano-silica to foam concrete has a 20% growth in compressive strength and 38% growth in tensile strength. Nanosilica and rice husk ash decreased by 21% and 9% decrease in concrete shrinkage due to decreased absorption of foam concrete. Polypropylene and synthetic fibers cause 6 to 15% reduction in the contraction due to concrete drying. Manuscript profile -
Open Access Article
58 - Performance of Porous Concrete Containing Additive in Reduction of Urban Runoff
Ehsan Teymouri s.farhad musavi hojjat karami saeid farzinOne of the cases of human intervention in environment is vast variations in making parts of the land surface impervious, followed by changes in the hydrologic cycle. Porous concrete is an especial type of highly pervious concrete, compatible with the environment, and co MoreOne of the cases of human intervention in environment is vast variations in making parts of the land surface impervious, followed by changes in the hydrologic cycle. Porous concrete is an especial type of highly pervious concrete, compatible with the environment, and could be used a method to increase surface infiltrate and reduce urban runoff. In the present experimental research, to improve the performance of this type of concrete, effect of adding lightweight pumice and perlite (0.6-1.2 mm), and adding 10% fine grains to the samples, was investigated. In this respect, the effective parameters for using porous concrete in urban runoff system, such as compression strength, hydraulic conductivity and porosity of the samples were measured. Analysis of experimental results was performed by using SAS 9.4 software at 95% confidence level. Results showed that adding fine grains to porous concrete increases compression strength and reduces hydraulic conductivity and porosity. Addition of lightweight pumice increases compression strength and reduces hydraulic conductivity and porosity of porous concrete. But, lightweight perlite reduced all three parameters of hydraulic conductivity, porosity and compression strength. In general, lightweight pumice, which has higher density and more pore space in its structure with respect to perlite, had better performance. Manuscript profile -
Open Access Article
59 - Modelling effective factors in strengthening RC beams from the construction management view
habib allah poornamazian mohsen izadiniaStrengthening reinforced concrete beams using fiber reinforced polymer (FRP) materials compared to other strengthening methods due to its low weight and easy transportation, high resistance with less manpower has been accepted as a common practice in most countries. Ext MoreStrengthening reinforced concrete beams using fiber reinforced polymer (FRP) materials compared to other strengthening methods due to its low weight and easy transportation, high resistance with less manpower has been accepted as a common practice in most countries. Externally bonded reinforcement (EBR) and near surface mounting (NSM) reinforcement are common methods for FRP installation. In this research the strengths, weaknesses, opportunities and threats of these two methods are identified as the strengths, weaknesses, opportunities, and threats (SWOT) method from the perspective of construction management and then the structural equations modeling (SEM) method is used to investigate the relationship between each of these variables. Two separate models were used in the EBR and NSM methods that identify the relationship between strengths, weaknesses, opportunities and threats as hidden variables and then questionnaire questions related to each of these variables as explicit variables. Also, confirmatory factor analysis and Cronbach's alpha coefficient were used to assess the validity and reliability of the questionnaire, respectively. The results of this study showed that each of the EBR and NSM methods has different advantages and disadvantages and then management solutions were evaluated using SWOT technique and structural equation modeling. Manuscript profile -
Open Access Article
60 - Investigating the effect of glass fiber on the toughness of fiber reinforced concrete
mahammad ali dashti rahmat abadi seiyed hamid shahabifar alireza rasekhi sahneh saeid zeinaliFiber reinforced concrete (FRC) has been used widely due to its advantages over plain concrete such as high energy absorption, post cracking behavior, flexural and impact strengths, arresting shrinkage crack. Toughness is the amount of energy that a concrete can withsta MoreFiber reinforced concrete (FRC) has been used widely due to its advantages over plain concrete such as high energy absorption, post cracking behavior, flexural and impact strengths, arresting shrinkage crack. Toughness is the amount of energy that a concrete can withstand by impact forces before rupturing. Toughness is obtained from the area under the force - deflection curve in flexural and compressive test and is characterized by a coefficient called the toughness ratio. In this study, the effect of 3 percentage of glass fiber (1,2 and 3%) with two different size of 3 and 6 millimeter on flexural and compressive toughness of FRC were investigated. The flexural and compressive toughness were carried out in accordance with the JSCE-SF4. The results indicate that by increasing the length of glass fiber, there is no significant change in the amount of flexural toughness. Mixtures with 3% glass fibers has the highest flexural toughness and mixtures with 2% glass fibers has the lowest flexural toughness. Among mixtures with the same length, the mixture with the higher percentage of glass fiber had the highest compressive toughness. Manuscript profile -
Open Access Article
61 - Numerical Study of a Reinforced Concrete Frame with Low Yield Point Infill Plates
aman hassanzade rahimabadi yahya nasiraa ali ghamariThe first steel shear walls were mainly utilized in retrofitted form, but steel shear walls are now known to offer reliable performance without stiffeners. With low thickness and yield strength, the plate would buckle under small loads, transitioning from an in-plane sh MoreThe first steel shear walls were mainly utilized in retrofitted form, but steel shear walls are now known to offer reliable performance without stiffeners. With low thickness and yield strength, the plate would buckle under small loads, transitioning from an in-plane shear mechanism to the diagonal tension field. Using ABAQUS, the present study takes a numerical approach and investigates a three-story, single span Reinforced Concrete Frame (RCF) with Low Yield Point (LYP) steel infill plates. A total of 45 models were studied. The yield stress of the shear wall, shear wall thickness, and the span-to-height ratio of the RCF were evaluated for the RCF, and the numerical models were compared in terms of secant stiffness, yield load, maximum load, yield displacement, and dissipated energy. Changing the span-to-height ratio and the thickness and yield strength of the LYP steel plate, increased the secant stiffness by, respectively, 49.39, 45.59, and 59.67%, the ultimate strength by 27.64, 30.88, and 40.73%, and energy dissipation by 32.35, 34.19, and 44.9%. The failure modes in the numerical models of RCFs with LYP steel plate shear walls resulted from local buckling and wrinkling of the steel infill plate. The yield strength of the LYP steel plate was found to control the stiffness, flexural strength, and energy dissipation in the RCF with a steel plate shear wall. Moreover, longitudinal cracks were created in the concrete in columns and beams due to the transfer of momentum by the tension field of the steel infill plates. Manuscript profile -
Open Access Article
62 - Study of the Behavior of Composite Steel Columns Filled with Short (non-slender) Concrete with (L)-shaped Geometric Cross Section under Numerical Sensitivity Analysis (FEM) with Axial Compression Loading
seyed ali mousavi davoudi morteza naghipourIn recent years, the use of concrete-filled steel sections (CFST) has been widely used for many benefits, including excellent seismic performance, high strength, high flexibility and energy absorption capacity relative to concrete (RC) and steel sections in the construc MoreIn recent years, the use of concrete-filled steel sections (CFST) has been widely used for many benefits, including excellent seismic performance, high strength, high flexibility and energy absorption capacity relative to concrete (RC) and steel sections in the construction industry. These columns are often more commonly used in the form of circles. The main reason for this is the point that circular sections create more enclosure than other sections in the core concrete. This makes the circular sections more widely used in columns (CFST) than in other sections. However, in some cases, the use of circular sections will be impossible, including architectural considerations, the implementation of more economical and easier connections in the quadratic sections than the circular sections, these causes certain shapes, including sections Square and flat sections and sections with L and T shape shapes are used in some parts of the building. considering the importance of this issue in this paper, we tried to introduce and investigate the mechanical behavior of short columns (CFST) with L-shaped geometric section and study the parametric effect of steel wall thickness and compressive stress of concrete on the capacity and mechanical behavior of these columns at the end and after analysis of the study samples, it was determined in the finite element analysis (FEM) that, in columns (CFST), the effect of the thickness of the steel structure was more effective on the capacity and mechanical behavior of the columns (CFST) with the geometric cross section L will be the shape. Manuscript profile -
Open Access Article
63 - Evaluation of Rheological and Mechanical Properties of Lightweight Concrete Containing Different Percentages of Polypropylene and Zeolite Fibers
Abdolkarim Abbasi Dezfouli Rezbeh AghajaryLightweight concrete is one of the most important and efficient materials in the modern construction industry and has a variety of applications. Proper application of lightweight concrete can have many positive influences on the construction process of concrete structur MoreLightweight concrete is one of the most important and efficient materials in the modern construction industry and has a variety of applications. Proper application of lightweight concrete can have many positive influences on the construction process of concrete structures. The possibility of application in the most geographical regions, utility of natural and cheap materials, high speed, low cost compared to the large volume of operations and its ductility due to the geometric shapes of the design, good performance and very high resistance, resistant to compressive forces and tensile strength, energy absorption and cracking stability are the prominent features of lightweight structural concretes. The main purpose of this research was to investigate the rheological and mechanical properties of the lightweight concrete containing different percentages of zeolite and polypropylene fiber separately. In this research, applying laboratory method, the rheological properties of fresh lightweight concrete (soft concrete) and the mechanical properties of hardened lightweight concrete at the ages of 7 and 28 days have been evaluated. According to ASTMC 39 standard, two samples of lightweight concrete without zeolite and polypropylene at the ages of 7 and 28 days have been prepared and mechanically evaluated. Then, in continuation of preparing of the light concrete samples prepared based on ASTMC 39 standard, three mixing designs with different percentages of polypropylene fibers (0.9, 1 and 1.1%) and 3 mixing designs with different percentages of zeolite (5, 10 and 15%) , at the mentioned ages were examined and compared with the base samples in the laboratory, which resulted in the following findings: Lightweight concrete samples containing zeolite had a higher electrical resistance than lightweight concrete samples containing polypropylene and the highest compressive strength was related to lightweight concrete samples containing 15% zeolite. This is equivalent to 400.75 kg / cm3 at the age of 28 days. Manuscript profile -
Open Access Article
64 - Determination of the Properties of Self-compacting Concrete Containing Metakaolin as a Replacement for Cement and Limestone Powder
Seyed Fathollah Sajedi Milad OrakToday, the tendency to use self-compacting concrete (SCC) is expanding due to its advantages. Manufacturing of SCC requires increasing the amount of cement used, which will result in the more environmental pollution due to the increased cement production, trying to use MoreToday, the tendency to use self-compacting concrete (SCC) is expanding due to its advantages. Manufacturing of SCC requires increasing the amount of cement used, which will result in the more environmental pollution due to the increased cement production, trying to use pozzolans to reduce cement consumption will be an essential step towards sustainable development. So, efforts to use pozzolans to reduce cement consumption will be an essential step towards sustainable development. Accordingly, in this study, by replacing a part of the cement and limestone powder with metakaolin as an active pozzolan, some properties of the produced concrete including rheology, mechanical and durability were evaluated. For this aim, metakaolin with 10%, 15%, 20%, 25% and 20%, 25%, 30%, 35% replaced the cement and limestone powder, respectively (without changing the cement content). The self-compacting properties of the concrete specimens were evaluated in the form of slump flow tests, L-box, U-box and J-ring, as well as mechanical properties including compressive and splitting tensile strength, and durability including water penetration depth and rapid chloride ion penetration (RCPT). The results present that the utility of metakaolin in the manufacturing of self-compacting concrete as an independent alternative to the part of cement and limestone powder has improved the mechanical properties of concrete, but has reduced its consistency. In order to solve this problem, it is necessary to increase the percentage of consumable superplasticizer used until it reaches the desired consistency level. Replacement of cement by 20% metakaolin reduced water permeability and RCPT by 35% and 20%, respectively, and replacing of the limestone powder by 35% metakaolin reduced water permeability and RCPT by 70% and 35%, respectively. Manuscript profile -
Open Access Article
65 - Comparative Study of the Mechanical Properties of the Concrete Reinforced with Industrial Steel Fibers and Recycled Metal Chips
Farhad Jireh Ziaaddin Zamanzadeh Leila JaliliIn recent years, most of the experimental studies have been performed on the mechanical behavior of reinforced concrete with recycled and industrial steel fibers in foreign countries, and it is necessary to conduct studies on fiber reinforced concrete made from existing MoreIn recent years, most of the experimental studies have been performed on the mechanical behavior of reinforced concrete with recycled and industrial steel fibers in foreign countries, and it is necessary to conduct studies on fiber reinforced concrete made from existing materials in our country. In this paper, experimental and numerical research on the mechanical behavior of the fiber concrete has been conducted. In the experimental program, first, by modeling the mix design presented in previous research for recycled fiber concrete, two mixing designs were determined in accordance with the available materials of the country, so that by adding two different types of steel fibers, the desired slump flow is obtained. The effect of industrial fibers and recycled metal chips on the compressive and splitting tensile behavior of fiber reinforced concrete was investigated by performing compressive and tensile tests. The addition of industrial fibers and recycled metal chips has slightly reduced the indirect compressive and splitting tensile strength of the concrete. In the simulation and modeling of finite element compression tests, the formation of cracks in the concrete elements surrounding metal chips elements, confirmed the occurrence of stress gradients in these concrete elements, which led to a reduction in the compressive strength of the fibre reinforced concrete. Manuscript profile -
Open Access Article
66 - Nonlinear Behavior of a Reinforced Concrete (RC) Building Strengthened with CFRP Under Progressive Collapse Based on Alternate Path Method
ali delfani armin aziminejhad abdolreza sarvghadmoghaddamThe spread of an initial local failure from element to element, eventually resulting in the collapse of an entire structure or a disproportionately large part of it is defined as progressive collapse. Occurrence of events such as blast, firing, vehicle collision and err MoreThe spread of an initial local failure from element to element, eventually resulting in the collapse of an entire structure or a disproportionately large part of it is defined as progressive collapse. Occurrence of events such as blast, firing, vehicle collision and error in design calculations or construction could cause local damages to structures. Although prospect of progressive collapse is not considered in ordinary buildings, such incident could result in significant human casualties, economic losses, and security threats in buildings which fall into very high importance categories. In this paper progressive collapse analysis is briefly presented and then nonlinear behavior of a seven-story reinforced concrete building with special resisting moment frame designed against seismic loads is evaluated under progressive collapse in accordance with Unified Facilities Criteria, UFC4-023-03 code, based on alternate path method using SAP software. It is observed that the structure is unable to meet the requirements presented in the UFC. Thus, weak beams were strengthened in flexure by carbon reinforced polymer (CFRP) fabrics. Results of the analysis indicate that the adopted method greatly enhances continuity and strength in beams adjacent to the lost column and hence in plastic hinge development, remaining the damage to be local. Manuscript profile -
Open Access Article
67 - An experimental study on effects of glass fiber and Metakaolin on the rheological, mechanical, and durability properties of self compacting concrete
Mir Pouya Naseri Alavi Payam Shafiei Hassan Javanshir Previous studies has shown that reinforced self-compacting concrete with fiber is more suitable for structural performance. The purpose of this study was to evaluate the effects of Metkaolin and alkali resistant glass fibers on the performance o More Previous studies has shown that reinforced self-compacting concrete with fiber is more suitable for structural performance. The purpose of this study was to evaluate the effects of Metkaolin and alkali resistant glass fibers on the performance of self-compacting concrete. In this study, the rheological properties (L-Box, Slump flow, T50) and mechanical properties (compressive strength, tensile and flexural strength), and durability (chloride ion penetration and water absorption) have been investigated. The results of the experiments showed that by increasing the amount of fiber, the concrete performance decreases. It was also found that the glass fiber had no positive effect on the compressive strength of the concrete. The tensile and flexural strength of self-compacting reinforced concrete increases with increasing fiber content. Durability studies have shown that the presence of glass fiber initially increases the resistance to chloride ion penetration and then reduces it, and also increases the gradual absorption of concrete water. The results of the experiments showed that the simultaneous presence of Metkaolin and glass fibers with optimal percentages can significantly improve the mechanical properties and durability of self-compacting concrete Manuscript profile -
Open Access Article
68 - behavior pattern of Compressive and tensile strength of structural lightweight concrete Consisting perlite, leca and Steel Fiber
Hossein Shaddel milad kheiri ghoje biglu abdollah enayati tekleConsidering that the weight of the structure increases the forces involved, especially the lateral forces such as earthquakes, so for this reason, as far as we can take the building path, we have been able to withstand earthquake resistance to the structure. Since, one MoreConsidering that the weight of the structure increases the forces involved, especially the lateral forces such as earthquakes, so for this reason, as far as we can take the building path, we have been able to withstand earthquake resistance to the structure. Since, one of the commonly used methods for producing the light eight concrete, utilizes the light weight aggregates with significant role in the concrete strength, proposing the optimized mix-design for the light weight concrete appears to be important. The result of experiments on 140 samples are representative of achieving to structural lightweight concrete according to ASTM C330 Standard which limits the specific gravity of structural light weight concrete to 1850 kg/cm3 and limits the minimum compressive strength of structural lightweight concreteto170 kg/cm3. Specific gravity and compressive strength of samples could be reached to defined limitation according to ASTM C330 Standard by using the very little particles of pozzolans and by changing in mix design Manuscript profile -
Open Access Article
69 - Numerical Study of the Position and Dimensions of the Openings on the Seismic Ductility of the Reinforced Concrete Slab - Column Connections Having Flexural Reinforcing and Shear Bolts
Nasibe motazaker mohamadali lotfolahiyaginABSTRACT Concrete slabs are of the main components of the concrete structures. Implementing flat slab is more simple and economic than other ones owing to it’s ease of formatting. Furthermore, the flat MoreABSTRACT Concrete slabs are of the main components of the concrete structures. Implementing flat slab is more simple and economic than other ones owing to it’s ease of formatting. Furthermore, the flat slabs mostly utilized in the buildings with relatively irregular plans of flat slab- column structures. Unfortunately, the typical structures are ready to punching are prone to shear failure, but such shear brittle failure can be controlled by reinforcing the shear. Shear bolts is a shear strengthening method the influence of which on the slabs has been investigated in the present study. In practical situations, it is often necessary to create openings in slab to allow electrical, water or air conditioning ducts to go through floors. The existence of openings and their form along with their dimensions and slab-column connections impact the strength and ductility of the slabs. These specimens were placed under vertical load and cyclic lateral loads. The vertical load for each specimen was kept and cyclic lateral load increased. When the peak tension created, displacement in different points of slab and ductility were compared among different specimens. The analysis results show that shear bolts can increase lateral peak load resisting capacity, the lateral drift capacity at peak load, and also the ductility of the slab-column connections. Shear bolts also change the failure mode of the slab-column connections. Shear bolts capacity of the slab resist the lateral loads increases. The square opening dimensions are smaller better and circular opening more ductility to square opening one with same space. Manuscript profile -
Open Access Article
70 - Study the Column's Behavior of Reinforced Concrete under Cycle Loadingbefore and after the Improvement with Polymer Fibers
sina kharazmi Alireza rasekhisahneh Today ,the process of seismic improvement and resistance has been accelerated in our country due to this fact that most current buildings has an old and non-standard context in our country . Studying the resis More Today ,the process of seismic improvement and resistance has been accelerated in our country due to this fact that most current buildings has an old and non-standard context in our country . Studying the resistance is inevitable case especially in the columns which is the most important and critical structural components . So , this study is conducted to investigation the column's behavior of reinforced concrete under cycle loading before and after the improvement with polymer fibers . In this regard , one laboratory study was used in order to modeling verification .Then , the appropriate approach was examined in order to study the .Arrangement of resistance of Polymer fibers in Abaqus finite element software with simulation with several various models . After studying the hysteresis –bar curves transformation, load-displacement curve cover – transformation , ultimate load and the contribution of polymer fibers of models was found that samples those have polymer fibers have a greater ability to more loading bearing and also , have more absorb property and more energy amortization than samples without fiber. Manuscript profile -
Open Access Article
71 - Numerical investigation of the perimeter Wall Behavior under blast Loading with the approach of protecting structures and facilities
yaser moeini ahmad ganjali Mohammad TajiBy increasing the risk of explosive terrorist attacks and threats to all types of structures and buildings, a careful study of the behavior of structures under explosive loading is considered as an important matter. A simple method to protect important structures agains MoreBy increasing the risk of explosive terrorist attacks and threats to all types of structures and buildings, a careful study of the behavior of structures under explosive loading is considered as an important matter. A simple method to protect important structures against explosive loads is to improve the security of the environment by using protective perimeter walls against explosive loading. In this research, the effect of reinforced concrete perimeter walls with and without canopy has been investigated. Different parameters such as the geometrical shape of the perimeter wall, the element removal and degradation rate, wall displacement, the scaled distance change and the explosive mass have been investigated. Finite element software (LS-DYNA (R11.1.0) has been used for modeling. For this purpose, the perimeter walls were designed in three different shapes and conditions. The results indicate that the existence of canopies for the perimeter walls under explosive loading has positive effects, so that the canopied perimeter walls with a canopy angle of 90 degrees compared to other types of wall, at different station distances and in the same conditions, reduce the displacement rate in the protected structure by about 11 percent. Furthermore, the location of perimeter walls and obtaining a safe distance in placing these walls is very effective in enhancing safety and reducing the vulnerability of the facilities and structures protected by these walls. Manuscript profile -
Open Access Article
72 - Investigating the Effect of Shear Walls Arrangement on Seismic Performance of High-rise Reinforced Concrete Buildings with Tube in Tube System
Amir Esmailzad ashkan khodabandelouAfter use new materials for use in construction, the invention of various structural forms can be considered as the most important factor in the feasibility of the construction of high-rise structures. The structural form of the building system is a system that tolerate MoreAfter use new materials for use in construction, the invention of various structural forms can be considered as the most important factor in the feasibility of the construction of high-rise structures. The structural form of the building system is a system that tolerates the various combinations of horizontal and vertical loads. The structure is taller and thinner the structural factors of the degree are more important and subsequently the need to choose the structural form is further increased [1]. In this regard, recently, in the design of high-rise structures, a new idea, the tube in tube system, has been presented by Fazlorkhan and Milestone, which has been used in many of the world's tallest structures, including the Oil Standard Building in Chicago and the World Trade Center building in New York. Therefore, in this research, by modeling a concrete structure with a height of 108 m and 28 floors (a basement floor) and adding shear walls to this system and applying different layouts for them, by SAP2000, the seismic performance of the structure under 7 accelerates has been investigated and the base cutting and displacement force of the roof is compared under different modes. The results show that as the location of the shear walls moves from the center of the structure to the outer layer, the seismic response of the high-order structure with the tube in tube system will be improved and the sections can be reduced for the cost-effectiveness of the project. Manuscript profile -
Open Access Article
73 - Determining the Behavior Coefficient of Flexural Frame of Special Reinforced Concrete with Shear Walls Having Openings Applying Numerical Analysis Method
Seyed Fathollah Sajedi Mostafa Echresh AmiriIran is located in a region that has critical conditions in terms of seismicity, so structures designed in the country must be resistant to lateral loads. Reinforced concrete shear walls are the most common systems resistant to the lateral loads of wind and earthquake i MoreIran is located in a region that has critical conditions in terms of seismicity, so structures designed in the country must be resistant to lateral loads. Reinforced concrete shear walls are the most common systems resistant to the lateral loads of wind and earthquake in the structures. One of the types of shear walls is the shear wall with openings, which are created for mechanical and architectural reasons. The presence of these openings in the shear wall causes changes in the ultimate resistance, changes in the behavior of the force distribution, and changes in the failure mechanism. Due to the fact that some shear walls are designed using old regulations that these regulations do not provide the ductility of the shear wall, so due to the incompatibility of the seismic design of these regulations with the new regulations, it is necessary to repair and strengthen these walls. Due to the fact that the effect of the wall with opening and reinforced with special flexural frame at a relatively high height was not studied in previous studies, so in this study, by studying the behavior of this type of frame, the coefficient of behavior of this type of system was evaluated. In this study, the concrete shear wall was added as a reinforcement to the flexural frame of the special reinforced concrete in two heights of 8 and 12 storeys, which were pre-designed, then circular, rhombic and rectangular openings were created in the walls and compared with each other. The results of the analyses present that the strength and behavior coefficient of the structure decrease with the opening of the wall, which is different for openings with different shapes. At the same level analysis, circular-shaped openings and among all openings, openings with half the original dimensions exhibited the best performance, indicating that the smaller the dimensions of the openings, the higher the structural strength. Manuscript profile -
Open Access Article
74 - Investigation of Shear Lag Phenomenon in High-Rise Reinforced Concrete Structures with Tube-in-Tube System under the Effect of Wind Load
Kourosh Mehdizadeh Seyede Vahide Hashemi Abbasali SadeghiThe tube-in-tube system is one of the most practical structural forms in high-rise buildings. One of the most important disadvantages of this system is the shear lag phenomenon, which increases the axial force in the side columns and decreases the axial force of the mid MoreThe tube-in-tube system is one of the most practical structural forms in high-rise buildings. One of the most important disadvantages of this system is the shear lag phenomenon, which increases the axial force in the side columns and decreases the axial force of the middle columns of the flange of structure. Therefore, in this study, the shear lag is investigated in high-rise reinforced concrete structures with tube-in-tube system with and without columns cut according to the height and plan under the effect of wind load. Thus, two high-rise concrete buildings, 40 and 60-story are modeled in ETABS 2017 software three dimensionally in three states. 40-story and 60-story prototypes are considered with and without columns cut in stories 11, 21 and 31, and then in stories 16, 31, and 46, respectively. Models were analyzed by wind force in order to calculate and compare the shear lag phenomenon. The results show that shear lag index has been changed from positive to negative phase at the height of building from the bottom to top and the axial force of the middle columns is higher than the corner columns in top stories. For example, the shear lag indices average is 1.2 and 0.61 in the 5th and 35th floors of 40-story building without column cut, respectively. Then the above values are 0.52 and 1.14 in the 5th and 55th floors, respectively for 60-story building without column cut. Also, the results indicate that the performance of structures has been improved at height by bundling of the columns in structures. Manuscript profile -
Open Access Article
75 - Comparative study of concrete structures designing based on the Standard 2800 fourth edition and regulation ASCE/SEI 7-16
Sasan Ghoflgar Ghasemi saeid javaherzadehExamining the results of calculation and designing of buildings bases on earthquake regulation is very important due to locating of Iran on earthquake belt. Standard 2800 fourth edition is currently the latest regulation of building designing against earthquake issued b MoreExamining the results of calculation and designing of buildings bases on earthquake regulation is very important due to locating of Iran on earthquake belt. Standard 2800 fourth edition is currently the latest regulation of building designing against earthquake issued by the Ministry of Roads and Urban Planning for designing of buildings. This regulation depicts the national determination and the government plans for reduction of the damages resultant from earthquake.In order to better understand the strengths and weaknesses of our country's law and to improve the defects in subsequent versions of the law, we compared the results of designing buildings according to Iran's rules and ASCE / SEI 7-16. In this paper concrete buildings 7 and 8 The height between the floors of 20.3 m and in two types of terrain II and III by Etabs 2016 software have been examined based on the two regulations. Based on studies carried out in accordance with the ASCE / SEI Regulations 7-16 in Iran, the use of a medium-ductile bending frame is not permissible, and the effects of the vertical load of the earthquake should be reconsidered, and it is suggested that the relative deformation for Categorize different individual hazards Manuscript profile -
Open Access Article
76 - Experimental Study of Compressive Strength of Geopolymer Concrete Based on XRF and SEM Analysis
Mohammadhossein Mansourghanaei Morteza Biklaryan Alireza MardookhpourIn this research, three mixing designs were made of geopolymer concrete containing 92, 96 and 100% composite blast-furnace slag including 8, 4 and 0% nanosilica, respectively. After performing the compressive strength test and selecting one of these three designs a MoreIn this research, three mixing designs were made of geopolymer concrete containing 92, 96 and 100% composite blast-furnace slag including 8, 4 and 0% nanosilica, respectively. After performing the compressive strength test and selecting one of these three designs as the optimal design in terms of superior mechanical properties, by adding 1 and 2% of polyolefin fibers to the optimal design, two more designs were made of geopolymer concrete. Concrete specimens were subjected to compressive strength tests (at 7, 28 and 90 days of curing), XRF (at 7 days of curing), and SEM (at 90 days of curing). The results were evaluated and compared with the results of a mixing design made of ordinary concrete containing Portland cement. The results of the analyses in this research exhibited the superiority in mechanical and microstructural properties of the geopolymer concrete in comparison with the ordinary concrete at all ages. At the 90-day curing age, as the best age in terms of performance, the minimum (62.43 MPa) and maximum (82.96 MPa) compressive strength values were obtained in designs 1 and 4, respectively. At this age, adding up to 8% nanosilica in geopolymer concrete enhanced the compressive strength up to 21.94% and adding up to 2% of fibers reduced the compressive strength up to 22.49% in this type of concrete. The results of XRF and SEM analyses overlapped with each other and were in accordance with the results of the compressive strength test. Manuscript profile -
Open Access Article
77 - Statistical Analysis of the Impact of Cold Joint on the Compressive Strength of Concrete Made by the National Method for Concrete Mix Design
Arash rafiei Ah karimiOne of the common problems in the implementation of concrete structures is seam or cold joint. The discontinuity in concrete body can cause structural weakness, increased permeability, reduced durability, corrosion of the rebar, and bad appearance of concrete. In this s MoreOne of the common problems in the implementation of concrete structures is seam or cold joint. The discontinuity in concrete body can cause structural weakness, increased permeability, reduced durability, corrosion of the rebar, and bad appearance of concrete. In this study, in order to evaluate the effect of cold joint on compressive strength of concrete, 192 cubic samples by national method of mix design in 4 modes, in which 48 samples without cold joint, 48 samples with horizontal cold joint, 48 samples with vertical cold joint, and 48 samples with diagonal cold joints were concreted in a 24-hour time interval. After 28 days of treatment with standard conditions by pressure cylinder device, the compressive strength of the samples was evaluated. After evaluating the results of the experiments, the values of the effect of cold joint on the compressive strength of the samples, the uncertainty and the probability of failure of the samples have been investigated. The results of analyzes indicate that, generally, the creation of a cold joint in concrete reduces the compressive strength of concrete. However, the reduction in compressive strength depends on the degree of cold joint to its angle. Also, the size of surface angle of the cold joint is also affected by the probability of failure. Manuscript profile -
Open Access Article
78 - Comparison of the effect of silica fume and fly ash on the mechanical properties of masonry recycled concretes
Mostafa Azhdarizadeh Seyyed Fathollah Sajedi Mohammad Sirous PakbazThe present study is devoted to the study of the effect of replacing silica-fume (SF) and fly ash (FA) pozzolans on the mechanical properties of recycled concrete (RC) made from recycled masonry coarse aggregates (RMCA). In manufactured concretes, natural aggregat MoreThe present study is devoted to the study of the effect of replacing silica-fume (SF) and fly ash (FA) pozzolans on the mechanical properties of recycled concrete (RC) made from recycled masonry coarse aggregates (RMCA). In manufactured concretes, natural aggregates were replaced by RMCA at different percentages. In order to improve the mechanical properties of these concretes, different percentages of SF and FA were substituted for part of the cement. Slump and specific gravity tests were performed on fresh concrete and compressive strength, splitting tensile strength, modulus of elasticity, and ultrasonic pulse velocity tests were performed on the hardened concrete. The results indicate that replacement of SF and FA increased the slump and decreased the specific weight of the concretes. Also, the results revealed that replacing 5% and 10% SF improved some mechanical properties of recycled concrete containing 50% of RMCA. Replacement of 15% SF, in concrete containing 25% of RMCA resulted in the close mechanical properties of RC compared with CC without pozzolans. Also, the test results demonstrated that replacing different percentages of Fly Ash, could not improve the mechanical properties of RC. Manuscript profile -
Open Access Article
79 - Evaluation and Research on the methods of manufacturing and mixing of various types of smart concrete
Abdolkarim Abbasi DezfouliSmart concrete refers to structural materials that can sense and respond appropriately to changes in their environment. This is done by changing one or more parameters. The smart properties of concrete are usually achieved by modifying and upgrading the concrete mix des MoreSmart concrete refers to structural materials that can sense and respond appropriately to changes in their environment. This is done by changing one or more parameters. The smart properties of concrete are usually achieved by modifying and upgrading the concrete mix design and matrix. It is mainly obtained by improving the composition of initional materials or adding functional materials to concrete. This concrete also has bionic (biological) characteristics. Compared to conventional concrete, properly designed smart concrete can be utilized to optimize the safety, durability and proper performance of infrastructure and reducing of the maintenance costs. The costs of use, resource consumption and environmental pollution, which are the basic parameters for construcction, will be reduced. Over the past few decades, significant efforts have been made to research smart concrete and many innovative achievements in the development and application of smart concrete are obtained. Thirteen types of smart concrete, with emphasis on their capabilities, are systematically investigated in this article, which is based on the principles, composition, construction, properties, research development and structural applications. In addition, some perspectives on the development of smart concrete are discussed. Finally, thirteen compositions of smart concrete were organized into a Table. Manuscript profile -
Open Access Article
80 - Evaluation and reliability performance determination of double- curved concrete dam (Karun 4)
peyman shademan mehdi amriThis paper seeks to design and shape a method for analyzing the functional reliability of the double-arch concrete dam. The quasi-stimulation was used to analyze the characteristics of possible concrete dam under seismic loading random stimulation is calculated. Meanwhi MoreThis paper seeks to design and shape a method for analyzing the functional reliability of the double-arch concrete dam. The quasi-stimulation was used to analyze the characteristics of possible concrete dam under seismic loading random stimulation is calculated. Meanwhile, response surface methodology based on the weighted regression method, combined with the reliability, performance calculated double-arch concrete. Finally, according to data from a random sample, was considered to be the convergence and stability of this method validation and analysis. Karun 4 earthquake-prone area of high seismic risk areas and the risks of earthquakes in this area is high. Keywords: concrete dam; random times, reliability function; quasi-stimulation Manuscript profile -
Open Access Article
81 - Investigation of Nonlinear Seismic Behavior of High-rise Reinforced Concrete Buildings and their Improvement by Viscoelastic Dampers
Faraz Kazemi ashkan khodabandehlouOwing to the destruction of high-rise buildings during recent earthquakes, the use of a structural system of reinforced concrete moment frame with viscoelastic damper causes a loss of seismic energy and consequently reduces lateral displacement. In this study a high-Ris MoreOwing to the destruction of high-rise buildings during recent earthquakes, the use of a structural system of reinforced concrete moment frame with viscoelastic damper causes a loss of seismic energy and consequently reduces lateral displacement. In this study a high-Rise, 20-Storey, three-dimensional reinforced concrete frame with 8 Models, of which 4 models with moment frame structural system and 4 models with moment frame + viscoelastic damping system in two directions of X, Y located in the high seismic zone (A=0.3g) on the soil type III is considered. The aim of the present study is to investigate the horizontal lateral displacement (absolute and relative) of the stories, the base shear of frames under gravity loads, and lateral loads of the earthquake. In order to modeling the viscoelastic materials, the Kelvin-Voigt model and to determine damping ratio(ζ) of frames with viscoelastic damper, stiffness coefficient (Kv) and damping coefficient (Cv) of viscoelastic dampers, the modal strain energy method have been applied. For seismic analysis of models without and with dampers, dynamic analysis of nonlinear time history via direct integration and modal (FNA) methods have been utilized, respectively. Geometric modeling of all frames was done using the SAP2000-V15 software. The results indicate that with increasing span length (model 2 compared to model 1 and model 4 compared to model 3) and increasing the height of stories (model 3 compared to model 1 and Model 4 compared to model 2), the maximum absolute lateral and relative displacement of stories, and base shear along with X, Y without and with viscoelastic damper have an increasing trend. Also, the maximum percentage increase of the mentioned models with damper compared to without damper along with X, Y has decreased Manuscript profile -
Open Access Article
82 - Experimental Study of Engineering Specifications of Concrete Containing Local Mineral Pozzolan based on XRD and SEM Analyses
Mojtaba Rangrazian Rahmat Madandoust Reza Mahjoub Mehdi RaftariGlobal warming and its effects on the environment can be considered as the important crises facing humans. Finding a method to reduce cement consumption can be an effective step in controlling the annual increase in global temperature. In this research, in order to find MoreGlobal warming and its effects on the environment can be considered as the important crises facing humans. Finding a method to reduce cement consumption can be an effective step in controlling the annual increase in global temperature. In this research, in order to find the optimal mixing design for replacing local mineral pozzolan instead of a part of cement, two mixing projects with four types of 5, 10, 15 and 20 percent by weight replaced a part of concrete cement.The compressive strength and concrete quality tests were evaluated in the specimens. The constituent elements of concrete and the effect of adding local mineral pozzolan were investigated using the XRD analysis, as well as the morphology and microstructural behavior of concrete with the SEM test. The results exhibited that the best replacement value of cement by pozzolan in concrete is equivalent to 15 percent by weight of cement. Pozzolanic samples increase the strength by 24% compared to plain cement concrete (PCC) samples. Optimal pozzolanic reaction reduced the amount of portlandite and calcite in concrete. Also, this pozzolan reduced the pores, increased the improvement and integrity of the interfacial transition zone (ITZ) in concrete in comparison with plain cement concrete. Considering the effects of this pozzolan on strengthening the structure and reducing the consumption of cement in concrete, the studied local mineral pozzolan can be introduced as a green material that reduces cement by increasing the strength of concrete and is environmentally friendly. Manuscript profile -
Open Access Article
83 - Experimental and numerical evaluation of rheological and mechanical properties of self-compacting concretes containing steel fibers and PET using response surface method (RSM)
hamed basser Taleb Moradi Shaghaghi hasan afshin saleh ahari saeed mirrezaeiIn the modern characteristics of concrete design based on daily needs, the use of recycled materials is an important and basic principle. Therefore, in the present study, PET (Polyethylene Terephthalate) has been substituted for fine aggregates in self-compacting concre MoreIn the modern characteristics of concrete design based on daily needs, the use of recycled materials is an important and basic principle. Therefore, in the present study, PET (Polyethylene Terephthalate) has been substituted for fine aggregates in self-compacting concrete. The aim of this study is to produce and optimize the mechanical and rheological properties of environmentally friendly self-compacting concretes. Input variables in the mixtures include (PET) as a substitute for a percentage of fine aggregates, steel fibers, powder stone as a substitute for a percentage of cement weight, and lubricant as a percentage of powder material weight. The studied responses are slump flow, L-box ratio (H2 / H1), compressive and tensile strengths. Mixing schemes were designed and studied using the Central Composite Design (CCD) method, which is one of the RSM (Response Surface Methodology) methods. The results demonstrated that with increasing PET, the rheological and mechanical properties of the mixtures decreased while the fibers effectively improved the reduction of strengths. Applying mathematical models provided by ANOVA, multi-objective optimizations were performed to maximize compressive strength by the RSM method and an optimal mixing scheme based on experimental results was proposed. Manuscript profile -
Open Access Article
84 - Evaluation of Nonlinear Seismic Behavior of Reinforced Concrete Flexural Frames with Special Ductility with and without Viscous Dampers on the Floors Level
siamak barmaki ashkan khodabandehlouThe main goal of this research is to evaluate the nonlinear seismic behavior of special RC moment with and without viscous dampers at the floor level. In this research, 2 high-rise three-dimensional RC building frames of 12 and 16 stories, each frame with 8 models, 4 mo MoreThe main goal of this research is to evaluate the nonlinear seismic behavior of special RC moment with and without viscous dampers at the floor level. In this research, 2 high-rise three-dimensional RC building frames of 12 and 16 stories, each frame with 8 models, 4 models with and 4 models without viscous damper at the floor level, located in the area with High seismicity on type 3 soil is considered. In order to seismic analysis of frames with and without viscous dampers, nonlinear static analysis method was used according to the second appendix of Iran earthquake regulations, fourth edition. The initial dimensions of the structural elements of the studied frames and the thickness of the roof slabs have been determined in ETABS-V15 and SAFE2014 software, respectively, and finally, modeling, gravity and lateral loading, and nonlinear static analysis of the studied frames have been performed in the SAP2000-V19 software. The results show that the change in the sections of beams and columns from square to rectangle in frames with and without viscous damper causes an increase in the relative lateral displacement of the floors, as well as an increase in the number of openings along the Y axis (model 1 compared to 3), and an increase in the length of the opening along the Y axis (model 1 Compared to 4), in frames with and without viscous damper, it reduces the absolute lateral displacement of floors. Manuscript profile -
Open Access Article
85 - A study on the flexural behavior of fiber-reinforced concrete beams subjected to tensile steel corrosion
iman sadrinejadThis paper presents the results of an experimental study on the flexural performance of reinforced concrete beams made of fibrous concrete under the corrosion of tensile steels. Fifteen reinforced concrete beams were prepared in three groups; in two groups, two types of MoreThis paper presents the results of an experimental study on the flexural performance of reinforced concrete beams made of fibrous concrete under the corrosion of tensile steels. Fifteen reinforced concrete beams were prepared in three groups; in two groups, two types of steel and polyolefin fibers were utilized to construct the beams. Four beams from each group were subjected to accelerated corrosion to create corrosion percentages of 3.5, 7, 15 and 30% in tensile steels. Then the beams were subjected to a four-point bending test, and the parameters of yield strength, ultimate strength, yield deflection, ultimate deflection, failure mode and ductility of the beams were investigated. The results indicated that up to the corrosion level of 15%, with the development of general corrosion, along with the reduction of stiffness and resistance of the beams, the ultimate deflection of the beams increased, and at the corrosion level of 30%, with the development of local corrosion, the ultimate strength and ultimate deflection of the beams were greatly reduced. The level of corrosion in tensile steel of beams containing steel fibers was lower than that of in the other beams, which was caused by the sacrificial anode effect of steel fibers. Under the corrosion conditions of tensile steel, the reduction of strength and stiffness in fibrous concrete beams were less than those in the plain concrete beams, and the performance of steel fibers in this field was significantly better than their polyolefin counterparts. Furthermore, the fibers used for this purpose, had significantly positive effect on the ductility of reinforced concrete beams with tensile steel corrosion. Manuscript profile -
Open Access Article
86 - Ranking of precast concrete railway bridges with water management criteria by TOPSIS method
Hossein Farshad Nader Abdoli Yazdi Ehsanollah EshtehardianWater management in rail transport as one of the important and effective parameters plays a major role in increasing the life span of rail structures and subsequently in the economic, industrial and social fields of countries. In this research, it has been tried accordi MoreWater management in rail transport as one of the important and effective parameters plays a major role in increasing the life span of rail structures and subsequently in the economic, industrial and social fields of countries. In this research, it has been tried according to similar experiences from past studies in this field and gathering the opinions of experts in the country, extensive field studies, the use of inspection checklists, statistical information and with the correct understanding of the failures related to water management in concrete bridges and Finally, with the TOPSIS method, according to water engineering standards in bridge maintenance and repairs, it is possible to rank the prefabricated concrete bridges of the General Directorate of Northern Railways of Iran based on water management standards. The results of this research will help employers and managers in charge to be able to properly manage bridges in water engineering, considering the available capital and limited resources. Manuscript profile -
Open Access Article
87 - Machine Foundations on Fiber Concrete Tunnel in Reinforced Sand
Alireza Hajiani Boushehrian -
Open Access Article
88 - Experimental Investigation of Strength and Water Absorption of Concrete Containing Desert Sand
Amir Hamzeh Keykha Jalal Najmaddini -
Open Access Article
89 - Investigation of the Pumice Additive Effect in Azarshahr Region on Mechanical Properties and Self-compacting Concrete Performance
Farhad Pirmohammadi Alishah Ayub Khandaghi Mehdi Mohammadrezaei Sattar Shafiei -
Open Access Article
90 - Combined Porcelain Ceramic and Recycled Concrete Aggregates Used as Replacement for Coarse Aggregates in Concrete
Sayed Behzad Talaeitaba Maedeh Dehghani -
Open Access Article
91 - Experimental Study of Modulus of Elasticity, Capillary absorption of water and UPV in Nature-Friendly Concrete Based on Geopolymer Materials
Mohammadhossein Mansourghanaei Morteza Biklaryan Alireza Mardookhpour -
Open Access Article
92 - Presenting a novel approach for estimation the compressive strength of high strength concrete using ANN & GEP
Seyed Azim Hosseini -
Open Access Article
93 - Seismic Evaluation of Tall Buildings with End Shear Walls by Fragility Curve
Ali Kheyroddin Mehran Akhavan Salmassi Ali Hemmati -
Open Access Article
94 - An Analytical Solution for Cylindrical Concrete Tank on Deformable Soil
Shirish Vichare Mandar M. Inamdar -
Open Access Article
95 - Nonlinear Analysis of Reinforced Concrete Columns with Fiber Reinforced Polymer Bars
Ehab M Lotfy -
Open Access Article
96 - Qualitative and Quantitative Seismic Evaluation of Reinforced Concrete Structures in Petrochemical Plant
Fariborz Nateghi-A Ali Rezaei-T -
Open Access Article
97 - Performance Characteristics of Carbon-nanofiber Blended Self Compacting Concrete
Sivakumar M V N -
Open Access Article
98 - Embedded carbon fiber‑reinforced polymer rod in reinforced concrete frame and ultra‑high‑performance concrete frame joints
Shahnaz Basim Farzad Hejazi Raizal Saifulnaz Bin Muhammad Rashid1 -
Open Access Article
99 - Estimating an appropriate plastic concrete mixing design for cutoff walls to control leakage under the earth dam.
A Pashazadeh M Khosravi N Ganjian -
Open Access Article
100 - Determination of Aerated Steps Number over Broad-Crest Stepped Spillways under Jet Flow Regime by using Artificial Neural Network
A Dolatshah H.R Vosoughifar -
Open Access Article
101 - Parametric Evaluation of the Static Stability Analysis of the Asphaltic Concrete Core Rockfill Dams
Arash Razmkhah Shahram Shiravi -
Open Access Article
102 - تعیین مقاومت کششی و رشد ترک یک بتن پلیمری معمولی با استفاده از نمونه های دیسک دایره ای
م.ر.م علیها م. حیدری رارانی م.م. شکریه م.ر آیت اللهی -
Open Access Article
103 - Mix proportioning of high-performance concrete by applying the GA and PSO
Alireza rezaee mohamad reza hasani ahangar -
Open Access Article
104 - مدل سازی تحلیلی و عددی پرتابه های فرسایشی در اهداف تقویت شده بتنی به الیاف فولادی
مهدی هدایتیان خداداد وواحدی در این مقاله به ارائه یک مدل تحلیلی فرآیند نفوذ پرتابه های فرسایشی در بتن تقویت شده به الیاف فولادی پرداخته شده است. نوآوری مدل تحلیلی ارائه شده در آن است که تاثیر طول به قطر الیاف فولادی و نسبت طول به قطر پرتابه و همچنین درصد حجمی الیاف استفاده شده در مات More در این مقاله به ارائه یک مدل تحلیلی فرآیند نفوذ پرتابه های فرسایشی در بتن تقویت شده به الیاف فولادی پرداخته شده است. نوآوری مدل تحلیلی ارائه شده در آن است که تاثیر طول به قطر الیاف فولادی و نسبت طول به قطر پرتابه و همچنین درصد حجمی الیاف استفاده شده در ماتریس بتن بر روی مقاومت ضربه ای بتن الیافی در سرعت های بالا مورد توجه قرار گرفته است.در شبیه سازی عددی از کد صریح و غیر خطی ال اس داینا استفاده شده است. پرتابه ها با سرعت 2500 متر بر ثانیه با جرم تقریبی 45 گرم و با سر نفوذگر نیم کروی، تخت و اجایو در بتن مسلح به الیاف فولادی با درصد های حجمی 1، 5/1 و 2 درصد نفوذ میکنند. پس از صحت سنجی مدل تحلیلی نفوذ با فرآیند شبیه سازی و کار آزمایشگاهی، نتایج نشان میدهد که پرتابه های با سر نفوذگر اجایو که فاکتور تیزی سر پرتابه پایینی دارد با سرعت باقیمانده بیشتری از اهداف خارج میشود و کارآیی آنها در نفوذ بهتر میباشد. به عبارت دیگر با افزایش نسبت طول به قطر پرتابه از 5/0 به 9/0، برای پرتابه هایی به ترتیب به شکل تخت، نیم کروی و اجایو، سرعت باقی مانده افزایش می یابد. همچنین با افزایش درصد حجمی الیاف فولادی در ماتریس بتن میزان تخریب سطح ناحیه رویی و زیرین بتن الیافی کاهش مییابد. مدل تحلیلی ارائه شده در فرآیند تغییرات سرعت پرتابه در حین نفوذ داخل بتن تقویت شده به الیاف فولادی از دستاوردهای مهم این تحقیق محسوب میشود. Manuscript profile -
Open Access Article
105 - Investigation of Effective Parameters on Compressive Strength, Specific Electrical Resistance and Water Absorption of Lightweight Pervious Concrete
shahriar gholamin noveirsar مرتضی جمشیدی رحمت مدندوستPervious concrete is a special type of lightweight concrete with low or even zero slump, which consists of cement, coarse aggregate, a limited percentage of fine aggregate (or no fine aggregate), various chemical and pozzolanic additives. In this article, structural LEC MorePervious concrete is a special type of lightweight concrete with low or even zero slump, which consists of cement, coarse aggregate, a limited percentage of fine aggregate (or no fine aggregate), various chemical and pozzolanic additives. In this article, structural LECA with a volumetric weight of 750 kg/m3 and a fixed water-to-cement ratio (W/C = 0.3) was used to make lightweight pervious concrete and the effect of different ratios of lightweight aggregate to cement (A/C) including 1.5, 1.8, 2.1, 2.4, 2.7, 3, total porosity and volume percentage of cement paste on compressive strength , specific electrical resistance and percentage of water absorption of lightweight pervious concrete aged 28 days were investigated. With the increase of A/C ratio from 1.5 to 3, the volume of cement paste decreased from 30.873% to 15.436% in the samples and the total porosity increased from 21.64% to 38.08%, which led to a decrease Specific electrical resistance decreased from 11.45 to 6.841 , compressive strength decreased from 13.27 MPa to 4.37 MPa, and water absorption increased from 11.185% to 12.695% in lightweight pervious concrete samples. The results of this research showed the improvement of physical properties and the decrease of mechanical properties and durability of lightweight pervious concrete containing LECA. Manuscript profile -
Open Access Article
106 - The Effect of PVA Fibers and Nano-Particles on the Bonding Strength of Fiber Reinforced Concrete
hossein nematian jelodar Ata Hojatkashani Rahmat Madandoust abbas akbarpour nik ghalb rashti Seyed Azim HosseiniRepairing and Strengthening of concrete structures is of special importance and the mechanical properties of repair mortars and their compatibility with the base concrete are significant aspects in the field of repairing of damaged concrete structures. The bond strength MoreRepairing and Strengthening of concrete structures is of special importance and the mechanical properties of repair mortars and their compatibility with the base concrete are significant aspects in the field of repairing of damaged concrete structures. The bond strength parameter of materials is one of the important properties in the selection of repair mortars. In the current Experimental studies, the bond strength of 7 types of cement base mortars consisting Nano-Silica (NS), Micro-Silica (SF) and Polyvinyl Alcohol (PVA) fibers have been tested on base concrete according to ASTM C882 standard. The base concrete is made of fiber concrete with a target compressive strength of 45 MPa and consisting macrosynthetic fibers. The workability of fiber concrete was 120 mm, and the method of curing the samples was done as the wet method. The obtained results indicate that all 7 types of repair materials of this research were compatible with the base concrete and the sample with the combination of PVA fibers and Nano-Silica in cement-based mortars has increased the bond strength of the samples by 85% compared to the samples without fibers. The highest bond strength among the samples was related to cement based mortar containing PVA fibers and Nano-silica (PVA0.75NS6) with bond strength equal to 21.83 MPa. Manuscript profile -
Open Access Article
107 - Prediction of compressive strength of concretes containing micro silica subject to carbonation using neural network
Ali DelnavazConcrete materials are exposed to special weather conditions, corrosion and significant damage. For this purpose, the effect of 28-day compressive strength changes on the samples studied in this study was investigated by considering the simultaneous effect of chloride i MoreConcrete materials are exposed to special weather conditions, corrosion and significant damage. For this purpose, the effect of 28-day compressive strength changes on the samples studied in this study was investigated by considering the simultaneous effect of chloride ion penetration and carbonation phenomenon. For this reason, in the first case, the samples are exposed to carbon dioxide once and then to chloride ions. In the latter case, only samples under the influence of chloride infiltration are examined. To make the samples, which include 9 mixing designs, three water-to-cement ratios of 0.35, 0.4 and 0.5 and three percent of 0%, 7% and 10% silica fume have been used. Finally, an optimal model is introduced to predict the compressive strength of concrete containing micro silica exposed to carbonation using artificial neural network. Also, a relation for estimating compressive strength based on the ratio of water to cement and the amount of silica is presented. Manuscript profile
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