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List of Articles
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Open Access Article
1 - 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
2 - Spatial Analysis and Handling of High-rise Buildings from Reinforced Concrete Core Internal Resistant Pipe System under Dynamic Loads on the Tube
Saeed Ghani Shayesteh Ashkan khodaBandehLouThe construction of high-rise structures around the world is rapidly increasing and this trend has been accelerated following the rapid economic growth and expansion of cities and increasing demand for space in populated areas. As these skyscrapers reach higher heights, MoreThe construction of high-rise structures around the world is rapidly increasing and this trend has been accelerated following the rapid economic growth and expansion of cities and increasing demand for space in populated areas. As these skyscrapers reach higher heights, they become a symbol of the power and superiority of technology advancement and economic development. Therefore, the use of new structural systems and modern construction technologies with the aim of reaching taller buildings considered by designers and engineers. In this study, a 26-story structure with 3-story underground with retaining walls is required to design against the lateral soil force of the surrounding area, that has a dual core system with tubular core modelled and dynamic analysis was performed under the influence of earthquake lateral force, and extent of lateral displacement of the structure and changes in force applied to its components were investigated in Sap2000 software. The tube in tube system indicated good performance against gravity and lateral forces and the maximum lateral displacement of the floors was within the permissible range due to the code and height of the structure concerned. Manuscript profile -
Open Access Article
3 - 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
4 - Simplification of Earthquake Accelerograms for quick time history Analyses by Using Their Modified Fourier Inverse Transforms
Alireza Faroughi mahmood hossseiniThere are several cases in seismic design of structures in which the simplified seismic analysis code is not applicable. In such cases most codes recommend time history analysis, which is very time consuming, mainly since the time step size of the digitized accelerogram MoreThere are several cases in seismic design of structures in which the simplified seismic analysis code is not applicable. In such cases most codes recommend time history analysis, which is very time consuming, mainly since the time step size of the digitized accelerograms is usually very small. Therefore, if the time history analysis can be performed by large time steps without losing much precision, it would be very helpful. In the present study, a method is introduced for simplification of accelerograms based on the modification of their fourier analyses. For this purpose, at first the fourier spectrum of the accelerograms is calculated. Then, by using a computer program, created by the authors, a modified version of fourier spectrum is produced and then the corresponding inverse fourier transform is calculated using a relatively large time step, which is computed based on the all major earthquake frequencies (which is usually 5 to 10 times larger than the original accelerograms time step) in order to create the simplified accelerograms. It is obvious that time history analysis by using this simplified accelerograms will be much less time-consuming. Numerical results indicate that the maximum response values obtained by using the simplified accelerograms have approximately 5 to 10 percent error depending on the type of the structure and earthquake characteristics Manuscript profile -
Open Access Article
5 - Investigation of the Effect of Trigonometric Rotation of the Column on Punching Shear Capacity in Two-Way Hollow Slabs Using Finite Element Metho
hadi azizian mohammad ali lotfollahi yaghin Alaaddin behraveshConsidering that the execution of column in two-way hollow slabs has some limitations especially in terms of architecture, so in some executions, the column has to be rotated, which will change the spherical balls spacing of the column edge and change the punching shear MoreConsidering that the execution of column in two-way hollow slabs has some limitations especially in terms of architecture, so in some executions, the column has to be rotated, which will change the spherical balls spacing of the column edge and change the punching shear capacity. In this field of study, no laboratory research and numerical analysis have been performed so far. In the present research , after calibration of ABAQUS finite element software to experimental results, the effect of square column rotation with different spherical balls spacing from column edge, on punching shear capacity and failure mechanism (areas prone to damage) in two-way hollow slab is investigated.The results present that by increasing the spacing of spherical balls from columnedge to (S ≥d) at different angles of rotation, the punching capacity increases and then stabilizes. Under conditions where the spherical balls' distance from the edge of the column is less than (d), the punching shear capacity is reduced by increasing the angle of rotation of the column. This is due to the presence of a damage-prone area at a distance less than (d). Manuscript profile -
Open Access Article
6 - 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
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