Seismic Response, Progressive Collapse Capacity of Irregular Buildings equipped with TADAS Damper

In recent years, the use of supplemental damping devices to increase the capacity of structures against progressive failure due to explosion has received less attention. The main purpose of this research is to investigate the effect of using Triangular yielding metal damper called TADAS. in order to increase the capacity of an irregular three and nine-story steel moment frame buildings against pulse like seismic excitations and progressive collapse effect. For this purpose, seismic performance level of this structure has been evaluated and rehabilitated by TADAS damper. The seismic performance level of damper-equipped building was evaluated by nonlinear static analysis (pushover) and also nonlinear time history analysis under various pulse-like ground motions. In order to assess the performance of TADAS damper under progressive collapse phenomenon, 12 critical columns considering side and corner locations proposed by GSA code were selected to remove. Then considering the seismic nonlinear response of these columns under selected ground motions, four critical scenarios were selected for each building. According to irregularity of the structural plan the capacity of the rehabilitated structure was evaluated using nonlinear time history analysis. To simulate the progressive collapse phenomenon at first the internal column forces are evaluated before it is removed. These forces are dynamically applied to the structure as a nodal point load in addition to existed dead and live loads in five seconds after removing the column. After completing the amount of loading they kept unchanged for two second and finally the nodal point loads would be removed over a fraction of second and therefor the dynamic sudden column removal was simulated.  The nonlinear response of the irregular TADAS-equipped building was computed through the step by step numerical integration method known as the Newmark’s β-method integration procedure using SAP2000 software. A fiber element model was employed to take into account the non-linear behavior of columns while for beam elements it is used plastic hinge model considering ASCE41 code. The dampers are also modeled using the link element in the software and the nonlinear plastic Wen model is assigned to simulate the nonlinear behavior of this element . The presented results include comparison of roof displacement diagrams, inter story drift and center mass acceleration for the structure with and without dampers in different failure scenarios. The seismic results show the ability of TADAS damper to improve seismic performance of irregular building. This control system could reduce the inter story drift of buildings at least 40% while the center mass acceleration increase 5.0%  While the hysteresis diagram of dampers indicates their ability to suppress the response of this structure. These results indicate the success of the damping system in the simultaneous control of acceleration and displacement and indicate another result of this study. On the other hands the progressive collapse analysis results show the ability of TADAS damper to improve the capacity of the structure against four types of progressive failure scenario especially in scenario 2. The results showed that the vertical displacement was reduced at least 15%.