Research On Application Of Buckling Restrained Braces In Multi-storey And High-rise Structure Of High Degree Seismic Regions

The three level seisimic fortification criterion of China is furtherly enhanced after the 2008 Wenchuan Earthquake.Designers usually tend to increase the section area and rebars area of the structure components to improve the seismic capacity of the structure as a traditional method.However,it is difficult to achieve the desired capacity by the traditional method due to the randomness of the seismic action.The buckling-restrained brace(BRB)is a kind of energy dissipation damper,which could be used as the brace to improve the lateral stiffness of the frame and the damper to dissipate the seismic energy under strong earthquakes.The BRB can be flexiblely assigned and the structure can be designed with diversity.The application of the BRB could improve the carrying capacity and seismic performance of the frame structure.A high-rise office building in an 8-degree seismic zone is taken as an example.The building is designed as a BRB-frame(BRBF)and a frame-shear wall(SWF),respectively to compare the seismic capacity between the two forms of the structural systems.The layout schemes of the two systems are designed and analyzed combined with the architectural function of the building.The seismic capacity of the two systems and the damping effect under the frequently occurred earthquakes are analyzed by the software PKPM.The practicability of the BRB-concrete frame is confirmed in this building,and its economical efficiency is also estimated.The response analysis of the two structure systems and the seismic capacity are conducted by the finite element method.It is concluded that the stress characteristics of BRB is not yield under small earthquakes,but yield under the big earthquake when it can provide energy dissipation.Compared with SWF,the BRBF system can avoid the shear wall with 400mm thickness and reduce the dimension of the structural member.At the same time,BRBF can improve the quality of the building and save the cost.The performance level of the two structural systems are obtained by the pushover method,and the distribution of the plastic hinges and the failure modes are also contrasted.Then the seismic capacity between the two systems are compared in this paper.Through the elastic-plastic analysis,the damage focuses on the coupling beam of SWF.There is a large area of moderate damage on the wall and column and failure mode is serious to the overall structure.However,the destruction zone is just beam end connected with BRB.Because of less severe damage to the column,it can be considered to strengthen the local part of the column in the design.In addition,some indexes such as the inter-story drift and the failure modes of the structure are compared and analyzed,and the design method of the BRB-concrete frame is proposed at the end of the paper to provide reference for the design staff.