Performance-based Seismic Design Method Of Multi-level Interchange Structure

Based on the summary of seismic research at home and abroad, multi-level fortificationwas adopted to discuss the seismic performance level and performance goals, as welll asmultilayer seismic fortification level city overpass structure. Then, the finite element methodand fiber model analysis method was adopted to conduct the research to the typical multilayeroverpass structure of plastic hinge and ductility capacity and other realtive designationproblems. a set of suitable forcity multi-level interchange structure seismic design based onperformance evaluation methods about the sectional curvature ductility coefficient as designparameters was systematically established. main studied results are listed as follows:Based on standard and the research results at home and abroad, the current economicsituation of our country and the existing norms of especially "cohesion" code for seismicdesign of Bridge City was considered, the city multi-level interchange structure seismicfortification levels5and seismic performance levels was proposed, the component disasterstatus of each level was gaved; the city of multilayer interchange bridge in order ofimportance are divided into4categories, the performance goal graph corresponding todifferent types of structural performance objective matrix and seismic fortification level wasalso proposed, it is sensible to easy reference in practical application.The time-dependent analysis method of the finite element software ANSYS was adoptedto study the multilayer overpass structure form of support and vertical seismic wavecomponent values and the values of damping ratio and other factors on the structure vibrationcharacteristics and the longitudinal and transverse direction of the bridge seismic response,the conclusion was drawed. The experience formula and specification requirements wascombined to give a ideal designation suggestion for selection of the multi-level interchangestructure dynamic response analysis in the vibration modes of the structure, and bearing typesetting, and expansion amount determination, and pier column elastic stage "double control",and damping ratio, and vertical component selection are given in6structural seismic.The fiber model of elastoplastic time history analysis method was adopted, and theinfluence of axial pressure and the girder stiffness and high order mode coupling effect of thebridge pier was considered, the plastic hinge position and range of variation with time wasstudied, the plastic hinge mechanism and development of the distribution diagram waspresented. On the basis of the research for the multi-level interchange energy dissipation ability and plastic hinge rotation and displacement and the section actual damage state and thecorresponding relations, the sectional curvature ductility index was presented to describe thestate of the damaged section method.Based on summary of the common damage model, relationship with multi-levelinterchange structure characteristics of stress and strain and curvature coefficient wascombined, according to the section force equilibrium principle and relation formulas, themulti-level interchange structure using curvature coefficient quantitative performancestandard formula was deduced, and section curvature ductility coefficient based on the saiddamage index and performance levels was further established.The damage index of the geometric average weighted distribution idea was adoted to putforward the curvature ductility factor for the individual components and the overall structureof the degree of damage model.Based on the whole damage index, the stage design method of elastic plastic structurescurvature ductility coefficient and detailed process was presented; the current standard wascombined to put forward a set of seismic-resistant design method for the seismic performanceof multilayer overpass structure performance, the basic principles including the content anddetailed procedures was expounded, it is for later use reference seismic multi-levelinterchange structure designation.