The Analysis Of Seismic Performance Of Concrete-filled Steel Tube Pier

With the advantage of high stiffness and well performance under pressure and earthquake, concrete-filled steel tube(CFST) becomes one of the most potential bridge pier types, especially in the earthquake area. And it is already adopted in the strengthening process of bridge piers after earthquake .This dissertation focuses on a series analysis to seismic performance of CFST structure, from nonlinear deformation ability of CFST component to dynamic characteristics and then seismic response of CFST frame pier. The major work of this dissertation is as follows :â‘ According to two commonly used constitutive models of CFST, a MATLAB program is coded by fiber model method in order to calculate the moment-curvature relationship of concrete-filled steel tube piers. Furthermore, the effect of confining coefficient, axial load ratio, compressive strength of concrete and yield strength of steel on nonlinear deformation ability is analyzed. Based on a great amount of calculations, a simplified method is put forward through Regression Analysis to acquire moment-curvature relationship of CFST component subjected to compress and flexure.â‘¡Through analyzing finite element model ,this dissertation discussed main parameters that influence natural frequency of CFST frame pier for the purpose of improving natural frequency. The main parameters include outline size of the frame (space between the columns), cross section size of each column, height of each floor, beam layout, and the size of beam section, etc.â‘¢According to the analysis of dynamic characteristics, and constantly adjust the beam stiffness, the impact of beam stiffness on seismic response of CFST frame pier is studied by response spectrum analysis.â‘£After analyzing the time-history results of two CFST frame piers under 3 earthquake waves, time-history change of different earthquake excitation and each seismic internal force are contrasted.