Research On Local Stress And Fatigure Performance Of Truss For The Concrete-Fille D Steel Tubular Arch Bridge

Hollow concrete joint is most used in many of our large-span hollow concrete truss arch bridges. When the hollow concrete truss arch bridge bears fatigue loads such as vehicle load, wind load and so on, the most vulnerable parts of the structure mainly are the joints of the connections between the hollows. At present, for the general study of hollow joints, a large number of research results have been made both at home and abroad, but research on performance of the hollow concrete joints is not mature. To the K-type hollow concrete joint of the hollow concrete truss arch bridge for the fourth bridge of Xiangtan as the background, through methods of experiments and finite element numerical simulation, have studied three aspects of the local stress characteristics of the hollow concrete joint, ultimate bearing capacity characteristics of the joint and fatigue performance:1. On the basis of static flexibility tests and finite element numerical simulation for the K-type hollow joint and K-type hollow concrete joint, has researched the performance differences between two kinds of joints and characteristics of stress concentration factor and hot spot stress, and analyzed the advantages and disadvantages by the use of different numerical models simulating local stress of the joint.2. Has researched the fatigue performance and fatigue life of the truss K-type hollow concrete joint in the axial load by using hot spot stress method based on the flexibility static test and finite element numerical analysis, and proved the accuracy and reliability of theoretical analysis and static flexibility test analysis results through the fatigue of truss K-type joint. Based on the regression analysis of fatigue life for joint, has calculated the S-N curve which used to assess the fatigue life of K-type hollow concrete joint.3. Has studied the failure mode of the truss K-type hollow concrete joint in the axial load through the ultimate bearing capacity damage test of the K-type hollow joints, and found that the assessment method of ultimate bearing capacity for the hollow joint using competent deformation as a failure criterion does not apply to the hollow concrete joint, and made a damage criteria is suitable for assessing ultimate bearing capacity of the K-type hollow concrete joint. For the capacity and ultimate bearing capacity of the K-type hollow concrete joint, has made a proposed formula.