فهرست مطالب سید علی رضوی طباطبائی

Reinforced-Concrete Shear Wall (RCSW) is a common lateral resisting system especially in mid and high-rise structures. This popularity among engineers is due to high ductility and in-plane stiffness of the RCSWs. RCSWs have shown good performance as seismic load-bearing systems in past earthquakes. However, the main disadvantage of RCSWs is the crushing of concrete at the foot of the wall and as a result the buckling of the reinforcement in this area, which makes it difficult and, in some cases, impossible to repair after the earthquake. As a solution, using Buckling-Restrained Brace (BRB) as boundary elements at the base of the RCSWs is proposed and investigated in this research. For this purpose, two sets of 6 and 12-storey structures with conventional RCSW and BRB-RCSW as lateral resisting system were designed, and their seismic response were assessed through static (monotonic and cyclic), dynamic Nonlinear Time History (NLTH) and Incremental Nonlinear Dynamic Analyses (NIDA). The results indicate improved structural performance and an increase of response modification factor from 4.4 in conventional RCSW to 5.47 in RCSW-BRB. Furthermore, the proposed system prevents the induced damage at the foot of the RCSW while the replaceable BRBs act as the fuses, increasing the resiliency of the structure. So that the behavior factor of the frame equipped with buckling-restrained braces increased by 30 percent in the 6-story building and 20 percent in the 12-story building.

Buckling-Restrained Braces (BRBs) are one of the new seismic resistant systems. The cross-sectional area and length of the BRB brace is one of the most important characteristics of these braces that directly affects the cost of BRB frames. Since beams, columns, and connections are designed for the maximum forces developed in BRB, the decrease in cross-sectional area of the BRBs decreases the steel consumption in the whole structure.The main purpose of this study is to optimize the weight of the structure, BRBs weight while uniforming the drift profile by changing the cross-sectional area and the length of the BRBs using genetic algorithms and other multi-objective optimization algorithms. Optimization is based on the results of nonlinear time history analysis under seven earthquake records using OpenSEES software. For this purpose, the objective function and constraints were defined in the genetic algorithm NSGA_II, MOPSO, MOEA_D, PESA_II, SPEA_II, and the initial population produced was entered as the initial cross-sectional area and length of the braces in the OpenSEES software. The optimization results show that for all three objective functions, the optimization values with high percentages of structural performance were optimized in such a way that the weight of BRB can be decreased up to about 50%.

The buckling-restrained braced frame (BRBF) is an appropriate lateral system for resisting seismic excitations. It is not yet an ideal system since there are deficiencies regarding the performance of this system. In this research resiliency of the reduced-length buckling restrained braced frames (RL-BRBFs) were assessed and compared with conventional buckling restrained braced frames (BRBF) as well as dual SMRF-BRBF. To do so two 4 and 9 story structures with conventional and reduced core length BRBs with diagonal and inverted chevron brace configuration were designed, then, the frames representing the lateral behavior of the structures were modelled in finite element software and time history analyses were performed on the structures under a set of 20 ground motion records. Seismic response of the structures including drifts and residual drifts were compared and reported herein. The results indicate that the reduced length BRBs have much better seismic behavior especially in the frame with moment resisting braced bay beam. The dual frame did not exhibit much different behavior compared to the braced frame with moment resisting braced bay beams. The moment resisting beams of the braced bays designed for the expected moment improved the drift response, plastic stiffness, and performed almost similar to the dual frame designed for 25% of the base shear. Furthermore, RL-BRBs are replaceable, repairable, and more cost-efficient compared to conventional BRBs due to smaller size of the reduced-length buckling restrained braces (RL-BRBF).