连续钢桁梁施工阶段整体节点局部应力分析

Local Stress Analysis of Integral Joint of Continuous Steel Truss Girder at Construction Stage

郑州黄河公铁两用桥主桥为国内首次采用无竖杆的三主桁斜边桁的空间桁架形式,其节点构造及受力复杂。主桥第2联连续钢桁梁采用悬臂拼装施工,为了解这种新型节点板在悬臂拼装施工最不利阶段时的局部受力情况,确保桥梁建造安全,建立第2联受力最大、有代表性的典型节点E80局部应力计算的精细有限元模型,进行节点板区域局部应力分析,得到节点板的应力分布情况。计算结果表明:在最大悬臂最不利工况下,与节点板相连接的各杆件主要承受压应力,应力水平低,分布比较均匀;节点板整体应力水平比较低,在节点板局部区域及下弦杆底板的某些区域应力值较大,出现应力集中,但应力值小于钢材的屈服强度,结构处于安全状态。

The spatial structure of three main trusses without vertical members and with two inclined side trusses has been applied to the main bridge of Zhengzhou Huanghe River Rail-cum-Road Bridge for the first time at home.The structure and stress conditions of the integral joints of the trusses are complicated and the second unit of the continuous steel truss girder of the bridge was constructed by the cantilever assembling and erection.To understand the local stress conditions of the joint plates of such type of the new joints at the most unfavorable stages of the cantilever construction and to ensure the construction safety of the bridge,the refined finite element model for calculation of the local stress of the typical joint E80 of the second unit truss girder that sustained the greatest stress was established,the local stress in the area of the joint plate was analyzed and the stress distribution of the plate was obtained.The results of the calculation show that under the longest cantilever and the most unfavorable load case,all members connected with the joint plate mainly sustain compressive stress,the stress level there is low and the stress is well distributed.The global stress level of the joint plate is low,the stress values of the local area of the joint plate and of some areas of the lower chord bottom plate are great and the stress concentration appears,however,the stress values are less than the yield strength of steel material and the structure is still in the state of safety.