【作者】 朱俊；

【导师】 童乐为；

【作者基本信息】 同济大学 ， 结构工程， 2007， 硕士

【摘要】 在我国的钢管混凝土拱桥和钢管混凝土空间桁桥中，焊接钢管混凝土节点已经被广泛应用。焊接钢管混凝土节点在日常车辆荷载作用下的疲劳性能是一个非常重要且有待研究的问题。然而，目前缺乏可作为参考的相似结构和设计规范，而且在理论上要解决也相当困难。本文所研究的内容是国家自然科学基金课题的一部分，主要是圆钢管混凝土T型焊接节点疲劳性能研究。钢管焊接节点疲劳设计方法有许多种，如名义应力法、热点应力法、断裂力学法，本文首先针对这几种方法进行简单的论述和比较。随后本文对圆钢管混凝土T型的焊接节点的静力试验做了简单介绍，进行圆钢管混凝土T型焊接节点静力试验的目的是测试节点焊缝连接部位在轴力作用下的热点应力特性和应力集中系数。根据测得的应力集中系数获得节点的热点应力，从而为后续进行的疲劳试验做铺垫。本文主要针对其中11个焊接节点(1个空钢管焊接节点、10个钢管混凝土焊接节点)进行轴拉力作用下的疲劳试验。为了了解节点相贯焊缝处的焊缝缺陷是否对节点的疲劳性能产生重要影响，在试验之前，对进行疲劳试验的节点进行无损检测。节点疲劳试验时，对疲劳裂纹的萌生位置、扩展路径、最后断裂作了全过程监测。最后，根据试验所得数据，并结合数学统计方法回归出一条适用于圆钢管混凝土T型焊接节点的S-N曲线，并回归出来的曲线与CIDECT、AWS、API、DnV提供的S-N曲线进行了比较。更多还原

【Abstract】 Welded Circular-Hollow-Section composite joints are widely used inconcrete-filled steel tube arch and space truss bridges in China. Fatigue behavior ofthese concrete-filled joints under daily vehicle load is very important problem thatneeds to be investigated. However, there is seldom similar structure for reference anddesign specification to guide now, and it is difficult to resolve it in theory. The studyof this paper is part of a research project of National Science Foundation Finance andis the study on fatigue behavior of welded T-joints of concrete filled circular hollowsection.There is a lot of design methods about the fatigue behavior of welded joints ofsteel tube, such as nominal stress method、hot spot stress method、fracture mechanicsmethod. Firstly, some introduction and comparison of those methods are carried out.Secondly, brief introduction about static loading experiment of welded T-jointsof concrete filled circular hollow sections is introduced. The purpose of staticexperiment is to get the stress concentration factor of joints under the axial force.Based on the measured stress concentration factor, hot spot stress is calculated.Fatigue experiments are performed on Eleven T-joints under axial tension force.Before the experiment, non-destructive detection is carried out, for evaluating thewelded deficiency to fatigue behavior of the joints. During the experiment of eachjoint, 24-hours monitor is carried out, for detecting the initiation and propagation ofcracks at weld toes in the intersection of joints.In the finally, based on the data measured in the experiment, S-N curve about thewelded T-joints of concrete filled circular hollow sections is obtained by linearregression analysis. The obtained S-N curve is compare to the exist S-N curveprovided by CIDECT、AWS、API、DnV.更多还原