Study On Seismic Performance And Design Method Of Steel Frame With Self-centering Components

As a form of earthquake resilient structure,self-centering structure can not only prevent the building from collapsing in earthquake,but also quickly restore its function after earthquake.The advantages of self-centering structure,such as economy and the rapidity of restoring building functions,are mainly reflected in the repair and regeneration after earthquake.Considering the whole life cycle cost of the building,it is a new structure form with development potential.However,there are some problems in the current research of self-centering structure,such as the self-centering component is complex,the load transfer mechanism is not clear,and the research results are mainly concentrated on the component which is lack of systematic seismic design method for the overall structure.In this paper,the seismic performance and design method of steel frame with selfcentering components are systematically studied from the component level and structure level.The main contents of this paper are as follows:The single-story and single-span steel frame with self-centering beam is designed and manufactured.The energy dissipation bar which is similar with buckling restrained brace is used as energy dissipation element.Based on analysis of stress mechanism,four frame specimens composed of different energy dissipation bars are conduct low cyclic loading test.The load transfer mechanism,energy dissipation capability and selfcentering capability of specimens are analyzed and compared.The results show that the structure has good seismic performance.After the horizontal force is unloaded and the energy dissipation bars are replaced,the structure can quickly restore the seismic performance which achieve the expected design goal.The self-centering column base is designed and manufactured.The energy dissipation bar is used as energy dissipation element.Based on analysis of stress mechanism,four specimens composed of different energy dissipation bars and different axial compression ratio are conduct low cyclic loading test.The load transfer mechanism,energy dissipation capability and self-centering capability of specimens are analyzed and compared.The results show that the structure has good seismic performance.After the horizontal force is unloaded and the energy dissipation bars are replaced,the structure can quickly restore the seismic performance which achieve the expected design goal.The refined models of self-centering moment frame and self-centering column base are established by using ABAQUS finite element software,and compared with the load test results to verify the effectiveness of finite element model.Based on the test results,the seismic performance parametric analysis of self-centering component is carried out,and the influence law of relevant design parameters such as section area of post-tensioned stands,initial stress of post-tensioned stands and section area of energy dissipation bars on the seismic performance of structure is studied.For the steel frame with self-centering components,in order to analyze the seismic performance from the structure level,the Self-centering Double Element Method based on ABAQUS is proposed to simplifiedly simulate on the self-centering components in the structure.The effectiveness of this method is verified by comparing with the low cyclic loading test results.Based on the Self-centering Double Element Method,the single-story frame models with self-centering beam,self-centering column base and two types of selfcentering components are established respectively.The seismic performance of structure under different layout forms of self-centering components is compared and analyzed,and the optimal layout principle of self-centering components in the structure is studied.Combined with the characteristics of the frame with self-centering components,the seismic performance design method based on four-level seismic fortification target for this frame is proposed.Different from the traditional three-level seismic fortification target,the four-level seismic fortification target is: " the structure is not damaged in frequent earthquake,basically intact in medium earthquake,can be repaired in rare earthquake,and do not collapse in extremely rare earthquake".In addition,the seismic action level,seismic performance level and limit state of the structure are defined.The seismic performance design objectives and seismic performance design indexes of the structure are determined.The realization method of four-level seismic fortification target is given.Under the established seismic performance target,taking a frame with self-centering components as the object,the seismic performance design is carried out.The seismic performance under rare earthquake and extremely rare earthquake is compared between the frame with self-centering components and traditional steel frame with same layout.Compared with traditional frame,the most remarkable feature of the frame with selfcentering components is that it can provide self-centering capacity for the structure,effectively control residual deformation of the structure after earthquake,and dissipate seismic energy through the energy dissipation members,so as to avoid damage of the main structure components.