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Research paper thumbnail of Study on the Response Coefficient of Setback Structures Compared to Regular Moment Frame Structures

Research paper thumbnail of Review on Seismic Rehabilitation of a 56Story RC Tall Building having Shear Wall System Based on A Nonlinear Dynamic Performance Evaluation

Tehran tower is a 56 story reinforced concrete tall building consisting of three wings with ident... more Tehran tower is a 56 story reinforced concrete tall building consisting of three wings with identical plan dimensions each approximately 48 meters by 22 meters. The three wings are at 120 degree from each other and have no expansions/seismic Joints. This paper contains the consideration of the retrofitting of the Tehran tower based on the findings of an exhaustive investigation of the nonlinear performance evaluation efforts. It has tried to show the procedure followed, methodologies utilized, and the results obtained for life-safety and collapse-prevention evaluation of the building. More over the weak zones of the structure due to analysis results are introduced and appropriate retrofit technique for satisfaction related life-safety and collapse-prevention criteria is presented. Actually in this project to improve the local behavior of coupling panels which are located regularly in main walls and definitely have been recognized as the most vulnerable structural elements, making use of steel plates which are connected to concrete members by chemical anchors has been used as the best retrofitting method for this case. Therefore in the final section of this paper it has been tried to explain the professional practical method utilized to perform the mentioned retrofitting project.

Research paper thumbnail of Numerical Investigation of Reinforced Concrete Frames Considering Nonlinear Geometric, Material and Time Dependent Effects with Incremental Construction Loadings

Reliable prediction of forces, stresses, and deflections in reinforced concrete structures has lo... more Reliable prediction of forces, stresses, and deflections in reinforced concrete structures has long been the goal of structural engineers. In fact analytical determination of the displacements, internal forces, stresses and deformations of reinforced concrete structures throughout their load histories has been complicated by a number of factors. Non homogeneity of the material, continuously changing topology of the structural system due to cracking of concrete under increasing loads, nonlinear stress-strain relationship of concrete and reinforcing steel, variation of concrete deformations due to creep, shrinkage, and applied load history are classified as complicating factors. Due to mentioned difficulties, engineers in the past have been relying heavily on empirical formulas derived from numerous experiments for the design of concrete structures. In this study, it has been tried to determine the real behavior and vulnerability of reinforced concrete frames in the basis of developed numerical nonlinear analytical procedure, considering nonlinear response of the structure. In fact, in order to obtain more accurate results, material and geometric nonlinearities plus time dependent effects of creep and shrinkage in addition to incremental construction loadings are included in the analyses. More over the structural response of the structure is traced through its elastic, inelastic and ultimate load ranges. The analyses are adopted with a finite element displacement formulation coupled with a time step integration solution. Also an incremental and iterative scheme based upon a constant imposed displacement is used so that local instabilities or strain softening can also be analyzed accurately.

Research paper thumbnail of Seismic evaluation of a 56-storey residential reinforced concrete high-rise building based on nonlinear dynamic time-history analyses

Structural Design of Tall and Special Buildings, 2010

In recent decades, shear walls and tube structures have been the most appropriate structural form... more In recent decades, shear walls and tube structures have been the most appropriate structural forms for the construction of high-rise concrete buildings. Thus, recent Reinforced Concrete (RC) tall buildings have more complicated structural behaviour than before. Therefore, studying the structural systems and associated behaviour of these types of structures is very important. The main objective of this paper is to study the linear and nonlinear behaviour of one of the tallest RC buildings, a 56-storey structure, located in a high seismic zone in Iran. In this tower, shear wall systems with irregular openings are utilized under both gravity and lateral loads and may result in some especial issues in the behaviour of structural elements such as shear walls and coupling beams. The analytical methodologies and the results obtained in the evaluation of life-safety and collapse prevention of the building are also discussed. The weak zones of the structure based on the results are introduced, and a detailed discussion of some important structural aspects of the high-rise shear wall system with consideration of the concrete time dependency and constructional sequence effects is also included. Copyright © 2010 John Wiley & Sons, Ltd.

Research paper thumbnail of Rehabilitation of a high-rise coupled shear wall system in a 56-storey residential reinforced concrete building (Tehran Tower), based on nonlinear dynamic time-history analyses

Structural Design of Tall and Special Buildings, 2010

Tehran Tower is a 56-storey reinforced concrete tall building consisting of three wings with iden... more Tehran Tower is a 56-storey reinforced concrete tall building consisting of three wings with identical plan dimensions each approximately 48 m by 22 m. The three wings are at 120° from each other and have no expansions/seismic joints. This paper contains the consideration of the rehabilitation of the Tehran Tower based on the findings of an exhaustive investigation of the nonlinear performance evaluation efforts. It has tried to show the procedure followed, methodologies utilized and the results obtained for life-safety (LS) and collapse-prevention (CP) evaluations of the building. Moreover, the weak zones of the structure due to analysis results are introduced and appropriate retrofit technique for satisfaction related to LS and CP criteria is presented. In this project, to improve the local behaviour of coupling panels that are regularly located in spine walls, and definitely have been recognized as the most vulnerable structural elements, making use of steel plates that are connected to concrete members by chemical anchors has been used as the best rehabilitation method for this case. Therefore, in the final section, the professional practical method utilized to perform the aforementioned project is explained. Copyright © 2010 John Wiley & Sons, Ltd.

Research paper thumbnail of Study on the Response Coefficient of Setback Structures Compared to Regular Moment Frame Structures

Research paper thumbnail of Review on Seismic Rehabilitation of a 56Story RC Tall Building having Shear Wall System Based on A Nonlinear Dynamic Performance Evaluation

Tehran tower is a 56 story reinforced concrete tall building consisting of three wings with ident... more Tehran tower is a 56 story reinforced concrete tall building consisting of three wings with identical plan dimensions each approximately 48 meters by 22 meters. The three wings are at 120 degree from each other and have no expansions/seismic Joints. This paper contains the consideration of the retrofitting of the Tehran tower based on the findings of an exhaustive investigation of the nonlinear performance evaluation efforts. It has tried to show the procedure followed, methodologies utilized, and the results obtained for life-safety and collapse-prevention evaluation of the building. More over the weak zones of the structure due to analysis results are introduced and appropriate retrofit technique for satisfaction related life-safety and collapse-prevention criteria is presented. Actually in this project to improve the local behavior of coupling panels which are located regularly in main walls and definitely have been recognized as the most vulnerable structural elements, making use of steel plates which are connected to concrete members by chemical anchors has been used as the best retrofitting method for this case. Therefore in the final section of this paper it has been tried to explain the professional practical method utilized to perform the mentioned retrofitting project.

Research paper thumbnail of Numerical Investigation of Reinforced Concrete Frames Considering Nonlinear Geometric, Material and Time Dependent Effects with Incremental Construction Loadings

Reliable prediction of forces, stresses, and deflections in reinforced concrete structures has lo... more Reliable prediction of forces, stresses, and deflections in reinforced concrete structures has long been the goal of structural engineers. In fact analytical determination of the displacements, internal forces, stresses and deformations of reinforced concrete structures throughout their load histories has been complicated by a number of factors. Non homogeneity of the material, continuously changing topology of the structural system due to cracking of concrete under increasing loads, nonlinear stress-strain relationship of concrete and reinforcing steel, variation of concrete deformations due to creep, shrinkage, and applied load history are classified as complicating factors. Due to mentioned difficulties, engineers in the past have been relying heavily on empirical formulas derived from numerous experiments for the design of concrete structures. In this study, it has been tried to determine the real behavior and vulnerability of reinforced concrete frames in the basis of developed numerical nonlinear analytical procedure, considering nonlinear response of the structure. In fact, in order to obtain more accurate results, material and geometric nonlinearities plus time dependent effects of creep and shrinkage in addition to incremental construction loadings are included in the analyses. More over the structural response of the structure is traced through its elastic, inelastic and ultimate load ranges. The analyses are adopted with a finite element displacement formulation coupled with a time step integration solution. Also an incremental and iterative scheme based upon a constant imposed displacement is used so that local instabilities or strain softening can also be analyzed accurately.

Research paper thumbnail of Seismic evaluation of a 56-storey residential reinforced concrete high-rise building based on nonlinear dynamic time-history analyses

Structural Design of Tall and Special Buildings, 2010

In recent decades, shear walls and tube structures have been the most appropriate structural form... more In recent decades, shear walls and tube structures have been the most appropriate structural forms for the construction of high-rise concrete buildings. Thus, recent Reinforced Concrete (RC) tall buildings have more complicated structural behaviour than before. Therefore, studying the structural systems and associated behaviour of these types of structures is very important. The main objective of this paper is to study the linear and nonlinear behaviour of one of the tallest RC buildings, a 56-storey structure, located in a high seismic zone in Iran. In this tower, shear wall systems with irregular openings are utilized under both gravity and lateral loads and may result in some especial issues in the behaviour of structural elements such as shear walls and coupling beams. The analytical methodologies and the results obtained in the evaluation of life-safety and collapse prevention of the building are also discussed. The weak zones of the structure based on the results are introduced, and a detailed discussion of some important structural aspects of the high-rise shear wall system with consideration of the concrete time dependency and constructional sequence effects is also included. Copyright © 2010 John Wiley & Sons, Ltd.

Research paper thumbnail of Rehabilitation of a high-rise coupled shear wall system in a 56-storey residential reinforced concrete building (Tehran Tower), based on nonlinear dynamic time-history analyses

Structural Design of Tall and Special Buildings, 2010

Tehran Tower is a 56-storey reinforced concrete tall building consisting of three wings with iden... more Tehran Tower is a 56-storey reinforced concrete tall building consisting of three wings with identical plan dimensions each approximately 48 m by 22 m. The three wings are at 120° from each other and have no expansions/seismic joints. This paper contains the consideration of the rehabilitation of the Tehran Tower based on the findings of an exhaustive investigation of the nonlinear performance evaluation efforts. It has tried to show the procedure followed, methodologies utilized and the results obtained for life-safety (LS) and collapse-prevention (CP) evaluations of the building. Moreover, the weak zones of the structure due to analysis results are introduced and appropriate retrofit technique for satisfaction related to LS and CP criteria is presented. In this project, to improve the local behaviour of coupling panels that are regularly located in spine walls, and definitely have been recognized as the most vulnerable structural elements, making use of steel plates that are connected to concrete members by chemical anchors has been used as the best rehabilitation method for this case. Therefore, in the final section, the professional practical method utilized to perform the aforementioned project is explained. Copyright © 2010 John Wiley & Sons, Ltd.