Seismic Behavior And Progressive Collapse Resistance Of Buckling Restrained Brace-Concrete Frame

The reinforced concrete frame system has been widely used in china,its design and construction technology is very perfect,but the lateral stiffness of the system is smaller.Under strong earthquake action,the axial force and shear force at the bottom of the frame column become larger,the concrete frame will appear weak layer,and then the structure will have serious local damage or progressive collapse phenomenon.BRB is a kind of energy dissipation damper of support type,it compensates the disadvantage of compressive buckling of common steel support,not only can increase the lateral stiffness of the framework,but also can play a role in the dissipation of energy,effectively reduce the earthquake response of the structure,protect the main structure component.With BRB performance is widely recognized,the research and application of BRB in the frame are increasing gradually.In this paper,BRB-concrete frames are taken as the object of study,the seismic performance,progressive collapse ability and design method of the frame are studied.The main work is as follows:The 1:3 scaled 2 Story 3 span BRB-concrete frame is simulated by the finite element software OpenSees,and the hysteretic curve and skeleton curve of the simulation are compared with the results of the frame test analysis,verify the rationality of the model established by OpenSees;On this basis,the numerical model of the original 8 story frame system is established,and the seismic performance of the structural system is studied by pseudo static analysis,Pushover and dynamic time history analysis.In addition,performance-based plastic design theory is introduced,use this method to design 6 story and 12 story of BRB-concrete frame,and the applicability of this method to the design of the frcame is verified by analyzing the case of frequent earthquakes and rare earthquakes;The progressive collapse analysis of the 6-story frame(2 pure BRB-concrete frame and 1 pure concrete frame)are carried out,analysis of the influence of BRB on progressive collapse of frames by using the alternate load path method.The results show that,the simulation results of OpenSees are in good agreement with the experimental results,and the established model can simulate the BRB-concrete frame better;BRB improves the lateral bearing capacity of the concrete frame,it also improves the energy dissipation capacity and stiffness degradation of the structure;In the analysis of the 8 story system,BRB still shows its stable energy dissipation performance,and the structural system exhibits good hysteretic behavior,when the structure is subjected to rare earthquake,BRB yield first as the first line of defense and improve the seismic performance of the structure.BRB-concrete frame designed by the performance-based plastic design method achieves the expected yield mechanism in the seismic analysis,and the method effectively controls the seismic performance of the structure,those verify the applicability of the design framework with this method.In addition,when a column of the structure fails and BRBs are arranged in the damaged span,the vertical bearing capacity of the residual structure will be increased,and the progressive collapse resistance of the residual structure can be improved.