Study On Seismic Performance Of Self-centering Toggle-braced Steel Frames

In order to solve the problem that self-centering components cannot meet large inter-story displacement and deformation due to the limitation of material elastic elongation at present,this paper analyzes the existing structural principles of toggle brace,obtains the relationship between inter-story lateral displacement and damper deformation when dampers are installed in different regions,and proposes a self-centering toggle brace system that places self-centering dampers in the displacement reduction region of toggle brace.Based on the research of common toggle brace systems,this paper explores the seismic performance and design application of self-centering toggle brace systems through theoretical analysis and numerical simulation.The main contents are as follows:1.Taking common forms of toggle-braced frame as examples,the scaling coefficients of toggle brace systems for different damper installation schemes are derived,and the theoretical relationship between the geometric parameters of the toggle brace system,the inter-story lateral displacement of the frame,and the scaling coefficients of displacement at the installed additional dampers is obtained.The distribution diagram of the initial displacement scaling region is drawn.2.Select a two-story frame model damaged due to earthquake in practical projects,and retrofit it with chevron brace connection dampers and frames as the benchmark frame.Conduct comparative research on seismic response analysis of a self-centering toggle-braced frame with the same initial stiffness and yield strength as the benchmark frame.Research shows that selfcentering toggle-braced frames can effectively reduce the displacement demand of dampers.3.The influence of different arrangements of dampers with the same parameters on the overall seismic performance of the structure is studied.Research shows that the larger the initial scaling factor of the toggle brace,the smaller the peak inter-story displacement angle under seismic excitations,but it may lead to an increase in the peak floor acceleration of the structure.4.The addition of viscous dampers to self-centering benchmark frame,self-centering toggle-braced frame,and original moment-resisting frame was explored,and the improvement of seismic performance of each scheme was compared.The conclusion shows that compared to moment-resisting frame,the improvement of seismic performance of self-centering togglebraced frame with viscous dampers is not a simple superposition of a single damper.The combination of the two types of damper can achieve better seismic performance.5.A direct displacement based design method for self-centering toggle brace system is proposed.A numerical example is analyzed using this method,and a finite element model is established for nonlinear time history analysis to verify the feasibility of the design method.The analysis results show that the direct displacement based design method can be effectively used for the design of self-centering toggle-braced frames;For high-rise self-centering toggle brace structures,due to the significant impact of higher order modes,the floor acceleration response of the high-rise section is relatively large.