Study On Mechanical Behavior And Fatigue Performance Of Anchorage Zone Of Cable-stayed Bridge With Composite Beam

Cable-stayed bridge takes a rapid increase in our country's bridge construction industry because of significant advantages.But in the design stage,cable-stayed bridges are usually simplified into skeletal structure for overall analysis,which is short of enough consideration on the stress status of the anchorage zones.Furthermore,the geometric nonlinearity of the cable-stayed bridge makes the stress status of anchorage zone more complex.How to ensure the safety of the anchorage zone is a crucial research content.This paper developes the researches from three parts which are the analysis on cable-tower anchorage zone,analysis on cable-beam anchorage zone,and anslysis on the anti-fatigue ability in cable-beam anchorage zone.First of all,through the discussion of the calculation methods for the stress status of the anchorage zone at home and abroad,it is known that most of the anchorage zone structures use the finite element method to calculate the structural details and assist in the full-scale test to verify the conclusions.Generally speaking,the results obtained from the finite element calculation are similar to those obtained by the full-scale test model,which proves that the finite element results are sufficient to meet the requirements of structural analysis when accurately simulating the structural forces.In this paper,a cable-stayed bridge with composite beam was analyzed as the supporting project,detailed analysis on the stress conditions of the cable-tower anchorage zone and cable-girder anchorage zone were carried out under the conditions that the overall structural force was calculated,the results prove that the structural members have enough safety insurance.Secondly,based on ASSHTO specification and China JTG D64 specification,fatigue vehicle loads are applied on the weld zone of the anchorage plate.The static analysis proves that the structures meet the requirements of fatigue design criterion in the specifications.Thirdly,based on the above analysis,the fatigue life of the weld zone under full-load and overload conditions with the standard load vehicle was calculated for the weld joint area of the anchorage zone.The calculated results shown that the welded zone has a great fatigue life.The overload impact on the life of the weld zone was significant and should be monitored during the service period of the bridge.Finally,based on the previous fatigue calculation,the possible initial cracks were taken into consideration,the fracture mechanics based Paris-formula was used to analyze the structural life of the anchor plate area.Considering the uncertainty of initial cracks,Monte-Carlo stochastic method was used to calculate the structural reliability of anchor plate area by MATLAB software.