Study On Reasonable Bridge State Of Self-anchored Suspension Bridge

Self-anchored suspension bridge retains the advantages of the earth-anchored suspension bridge.In recent years,this type of special structure is getting more and more favored in engineering field,because it has the advantages of beautiful line shape,novel appearance,clear mechanical relationship,good adaption to topographical geological conditions,good economic performance and great spanning capacity.Nowadays,a large number of self-anchored suspension bridges have been built at home and abroad.The reasonable design state of self-achored suspension bridge contains two aspects: its line shape and internal force.Under the commission of Key Project of Chinese National Programs for Fundamental Research and Development(2016YFC0701202)and Experimental Study on Static Performance of Main Cable Anchorage Zone of Egongyan Rail Service Bridge of Chongqing Metro(1042012920160261),this paper uses Egongyan rail service bridge,the three span self-anchored suspension bridge with two towers,as the research background.Based on summarizing the previous research results and design experience of some countries,the method of numerical simulation and finite element theory model are used to analysis the self-anchored suspension bridge main cable shape,the unstressed shape of the cable and the unstressed cable length.The static and dynamic performance is also as a part of the research in this paper.The main work and achievements of this paper are shown as follows:(1)The development history,the structure characteristics,mechanical characteristics and the research status of the reasonable design state at home and abroad of the self-anchored suspension bridge are reviewed in this paper.In addition,the three calculation theory of suspension bridge: elasticity theory,deflection theory and nonlinear finite element theory are discussed in this paper.(2)According to the previous research results and experience,a method of determining the reasonable design status is proposed.Three methods to calculate the alignment and internal force of the main cable are derived too,which are the traditional parabola method,the catenary method and the segmental catenary method.Expressions formula for static analysis of cables are concluded using these theories.and the calculation formulas of corresponding unstressed length are deduced too.This paper use Visual Fortran to program the formula the segmental catenary method and set a finite element model with Midas Civil to verify its applicability and accuracy.(3)According to the principle of unstressed cable length invariant,the catenary method is used to calculate the unstressed cable shape of self-anchored suspension bridge.The saddle offsetting and the deviation of clamps are calculated too.The applicability and accuracy of the analytical method are verified by the backward construction progress analysis of Egongyan rail service bridge.(4)In this paper,the mechanical performance of self-anchored suspension bridge is also studied in the condition of reasonable completed bridge.The influence on the static performance for Egongyan rail service bridge of structural parameters,such as rise-span ratio of main span,stiffened girder flexural rigidity,stiffened girder tensile rigidity,is studied.In addition,dynamic performance of Egongyan rail service bridge is calculated.Furthermore,the influence on dynamic performance for Egongyan rail service bridge of structural parameters,such as rise-span ratio of main span,dead load intensity,stiffened girder flexural rigidity,camber,stiffened girder tensile rigidity,and dead load intensity,is also studied.Through the research and analysis of the above content,a more comprehensive understanding of the reasonable design state of the self-anchored suspension bridge is made.The conclusion of this paper has reference value for the same type of bridge.