XML
-
-
List of Articles
-
Open Access Article
1 - The Study of Effects of Egg Shell Powder on The Attributes of Fresh Concrete and Hard set
Afshin Amiri Abdolkarim Abbasi Dezfooli Nowadays in most parts of the world, the technology for achieving the concrete with a higher durability has been revolutionized. The usage of the Pozzolan and other additives for this end, has become a common thing in the industry for the past f More Nowadays in most parts of the world, the technology for achieving the concrete with a higher durability has been revolutionized. The usage of the Pozzolan and other additives for this end, has become a common thing in the industry for the past few years. First, the Pozzolan being rather fine and second, its reaction to the Calcium Hydroxide existing in the concrete, are the two factors causing the reduction of the porosity of the concrete and its penetrability and also increasing its durability. This study investigates the effects of egg shell powder on the mechanical attributes of the concrete. In addition, the study attempts to find the optimized percent of the powder in order to reach a higher strength as well as experiments including the percentage of water absorption, the specific weight of the concrete, resistance test –indicating corrosion and permeability- and compressive test on the 15cm cube samples. The samples were prepared by 0%, 10 and 20% egg shell as cement replacement and were tested on 3, 7 and 28 days ones. The normal mixes of concrete were used. The result of the test shows that the samples with 10% replacement have a slump loss by 12%, increasing concrete strength by 1%, reducing in water absorption as 21%, increasing 2% in the specific density, and increasing electric resistance of 90% in comparison with control specimens (0%). The findings indicated the suitability of the egg shell as a waste material and as a replacement of cement in terms of quality and environmental pollution. Manuscript profile -
Open Access Article
2 - 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
3 - Evaluation of Reinforced Concrete Frames with Steel & Concrete X-Shape Brace Strengthened with CFRP under Cyclic Loads
ahmad rahbar ranji mohammad pasalariThe choice of lateral forces resistance system type depends on the composition of the loading, structural behavior, gravity loads transition to the base, architectural design, geometric dimensions, building code restrictions, the amount of lateral forces, the maximum di MoreThe choice of lateral forces resistance system type depends on the composition of the loading, structural behavior, gravity loads transition to the base, architectural design, geometric dimensions, building code restrictions, the amount of lateral forces, the maximum displacement and, etc. Today, the use of concrete dual frames has become very common in many modern structures, including high-rise buildings and building retrofitting. In this study, RC frames with X-shaped steel braces and Concrete X-Shape braces Strengthened with CFRP under Cyclic seismic loading have been investigated. Initially an RC frame in 3 manners such as RC frame, RC frame with concrete X-shaped braces and RC frame with X-shaped steel braces previously tested by Haddad et al. (2015) modeled and analyzed in ABACUS finite element software. Then the results of numerical analysis and laboratory study were compared. The results were fairly well-matched. Finally, after verification of the ABACUS software results, the proper composition of the carbon fiber reinforced polymer (CFRP) retrofitting was studied, and the load-displacement hysteresis diagrams, load-displacement and final load ratios for the proposed samples were compared. Manuscript profile -
Open Access Article
4 - Improvement of Loose Clayey Soil Layers Under Shallow Foundation with Using Geogrid
ramin vafaeipoor sadaf mahmoudi azarGeogrid as reinforcement in the present, can solve the problems with the construction of heavy structures and embankments on weak soils without need for piling or excavation operations. This is done by placing geogrid on weak soils Between them at appropriate distance MoreGeogrid as reinforcement in the present, can solve the problems with the construction of heavy structures and embankments on weak soils without need for piling or excavation operations. This is done by placing geogrid on weak soils Between them at appropriate distances then cut the failure surfaces This article is about geotechnical information of weak soil of Fereshteh street in Tabriz city. in the present study, two sides geogrid is widely used and parallel under foundation with burst zero, one, two, three and four meters. In the PLAXIS modeling software, model has been designed for statically and dynamically or seismic analysis and their behavior has been compared. according to the results by Construction of two layers of geogrid vertical settlement for this soil has been 4.30 centimeters in thirty days. Which has the lowest amount compared to other layers in this case this can help in preventing long-term soils settlement. This result can be used for the lands which there is no limit on the adjacent Residential structures to a radius of three meters. Manuscript profile -
Open Access Article
5 - Angular Earthquake Coefficient in Irregular Structures on Plan
Mohammad reza Bahari Alireza faroughi mohammad ghanoonibaghaToday is a common method of seismic design of structures in the regulations are based on the static method equivalent and Determine the base shear design by using The linear spectrum. To determine the base shear, a coefficient called earthquake coefficient is used. In t MoreToday is a common method of seismic design of structures in the regulations are based on the static method equivalent and Determine the base shear design by using The linear spectrum. To determine the base shear, a coefficient called earthquake coefficient is used. In this article first, Methods of calculation and factors affecting the behavior of factors are investigated. Then a number of steel structures with lateral load systems MRF and CBF, with the number of floors 3, 7 and 10 Irregular on the plan is evaluated. By performing a non-linear static analysis under the influence of lateral loads، Ductility and their coefficient of resistance in different angles Due to the limitation of local ductility in structural elements (Based on maximum drift) and finally the behavior coefficients (Given the values obtained from the analysis) will be counted. It is assumed that the angular behavior coefficients follow a rectangular rule so that the values of the angular behavior coefficient with the length of the line from the origin with the desired angle in a rectangle whose sides are the coefficient of behavior of the main structure of the structure is equal. Then, the values of the angular behavior coefficient obtained from this rule are compared with the values obtained from nonlinear static analysis. According to the results, it is also observed that the angular behavior coefficients obtained from this type of analysis are slightly higher than their values from the rectangular base, and follow this rule well. As well as structures at these angles relative to the main directions shows better behavior. Manuscript profile -
Open Access Article
6 - A Two Stage Method to Identification Cracks in Beam Structures
siyamak ghadimi seyyed sina kourehliIn this paper, a two stage crack detection method has been proposed. In the first stage, extreme learning machine used to identify crack using three fist modes frequencies and mode shapes as input data to train machine. In the second stage, the obtained results in the f MoreIn this paper, a two stage crack detection method has been proposed. In the first stage, extreme learning machine used to identify crack using three fist modes frequencies and mode shapes as input data to train machine. In the second stage, the obtained results in the first stage, used as initial population in optimization procedure to detect crack locations and severities accurately. To demonstrate the potential of the proposed analysis over existing ones, a validation study has been done. To evaluate the performance of the presented method, a simply supported beam and a cantilever beam. The obtained results indicated that this method can provide a reliable tool to accurately identify cracks in beam structures Manuscript profile -
Open Access Article
7 - Numerical Study on Behavior of Teduced – Beam Connections to T-Shaped Columns in Moment Resisting Frames
amin fallahi motlagh ahmad maleki Extensive studies carried out following the Northridge earthquake showed that several factors contributed to this failure. The high stress concentration in the welds and the attachment vulnerability to high ductility requirements were identified as tw More Extensive studies carried out following the Northridge earthquake showed that several factors contributed to this failure. The high stress concentration in the welds and the attachment vulnerability to high ductility requirements were identified as two main causes of this rupture. A logical way to solve this problem is to reduce the need for a weld in the welded areas and to lower the concentration level of stress. Several corrective methods have been proposed for the construction after the Northridge earthquake as well as the retrofitting of existing reinforced steel structures. One of these methods is the configuration of the shotgun. In this research, after verifying the modeling results using Abacus software, 9 models of modeling of the beam with the dropped wing to the cross column were modeled in three groups. The results of this study are as follows: Reducing the length of the graft has the greatest effect of shear force on non-elastic performance. The shorter graft shear submission mechanism is better than the flexural bending mechanism of the long joints, and the main reason is that in shear joints, the shear forces are constant throughout the bond, so non-elastic strains will be uniformly distributed throughout the graft. Also in the specimen with a 0.6b interval, which has the weakest function, the initial failure (third cycle) of the resistance drop has begun. So that the amount of energy absorption is lower than other samples. The non-cross-sectional sample with energy absorption of 9272 kN / m is 0.75b and 0.6b, respectively, with 11.5% and 66.6% respectively, with energy absorption and greater depreciation than other samples. In the specimen with a bone geometry in the elementary cycles (third cycle), the resistance drop has begun. So that the amount of energy absorption is lower than other samples. The sample with a circular cross section with an energy absorption of 8875 kN / m is 18.6% and 1. 54%, respectively, with a geometric bone and oval geometry, with energy absorption and greater depreciation than other specimens. Manuscript profile
-
The rights to this website are owned by the Raimag Press Management System.
Copyright © 2021-2024