Mechanical Performance Analysis And Optimization Of Combination System Bridge With Cable-Stayed Without Backstays And Continuous Beam

In order to meet different functional requirements,the basic bridge system can be combined to enrich and innovate the bridge structure system.The combination system bridge of the cable-stayed bridge without backstays and the continuous beam bridge can meet the requirements of aesthetics and spanning capabilities.And it can provide a new solution for the design of urban bridges.At present,there are few studies on mechanical performance analysis and optimization of combination system bridge,and many practical problems need to be further studied.The main contents of this dissertation are as follows:(1)Based on summarizing the development history,current research status and basic mechanical characteristics of cable-stayed bridge,cable-stayed bridge without backstays and combination system bridge with cable-stayed without backstays-continuous beam(patial cable-stayed bridge)were studied.Three finite element models of tower beam consolidation system,continuous beam and rigid frame system(conventional cable-stayed bridge without backstays)were established by finite element software of Midas/Civil.The structural mechanical performance of combination system bridge with cable-stayed without backstays-continuous beam(tower beam consolidation system)under dead load,live load and temperature load was analyzed.(2)The advantages,disadvantages and applicable scope of the existing method for determining the reasonable state of the cable-stayed bridges were analyzed.In addition,the fundamental theory and calculation process of the stress-balance method and influence matrix method were deduced in detail.The ratio of vertical component of cable force and dead load was proposed to initially determine the reasonable state of completed bridge.The stress balance method was used to determine the feasible region of the bending moment of the main beam and the pylon.Then the influence matrix method was used to achieve the optimization of the cable force by the software of MATLAB.Finally,the detail calculation steps for determining the reasonable bridge state of the combination system bridge with cable-stayed without backstays-continuous beam were summarized.(3)In order to study the influence of structural design parameters on the mechanical performance of combination system bridge,fine structural design parameters were selected.The detail design parameters were as follows: the tower obliquity,the ratio of tower and span,the distance between the cables in the girder,the girder stiffness and the tower stiffness.The sensitivity analysis of different parameters was performed by using the control variable method to reveal the influence on the mechanical performance of the combination system bridge.