Research On Seismic Response And Seismic Resistant Performance Of Steel-concrete Composite Beam Bridge Without Supported Transverse Beam System

The steel-concrete composite beam has already been applied to domestic highway bridges in recent years.However,seismic design is hardly carried out effectively by the lack of seismic damage data and research on seismic response and performance of steel-concrete composite beam bridges.This thesis is based on new steel-concrete composite beam bridges without supported transverse steel beams used in the Beiyanjiang highway in Anhui province.Refined finite element mode considering shear connectors for seismic design is developed for steel-concrete composite beam bridges.Effects of near-field pulse-like ground motions,far-field ground motions,shear stiffness of shear studs and uplift-restricted and slip-permitted connection on seismic response and performance of new steel-concrete composite beam bridges are presented.The main contents and conclusions of this thesis are outlined as follows:(1)Refined finite element mode considering shear connectors for seismic design is developed based on structural and seismic characteristics of new steel-concrete composite beam bridges without supported transverse steel beams.Influence of relative slip between concrete plate and steel beam and nonlinear characteristics of shear studs on seismic response of steel-concrete composite beam bridges is considered by use of refined finite element mode.Furthermore,the applicability of different finite-element modeling methods is presented.(2)Seismic response assessment of new steel-concrete composite beam bridges by use of near-field pulse-like ground motions is significantly larger than far-field ground motions with the increase of ground motion intensity.However,near-field pulse-like ground motion characteristics have few effects on max horizontal displacement of shear studs in the situation of large shear stiffness of shear studs.(3)Shear stiffness of shear studs has some influence on different seismic response parameters of bridges.The relative slip between concrete plate and steel beam and nonlinear characteristics of shear studs with the decrease of shear stiffness can reduce seismic response of new steel-concrete composite beam bridges.(4)Structural dynamic characteristics,max horizontal displacement and shear force of shear studs can obviously be changed by application of uplift-restricted and slip-permitted connection in the negative bending moment area.In addition,the application of uplift-restricted and slip-permitted connection can reduce the probability of cracking of concrete in the negative bending moment area and increase local stability of steel webs in the earthquake.However,uplift-restricted and slip-permitted connection has no influence on seismic response of pier,bearing and pile foundation.