考虑焊接残余应力下的索梁锚固结构主焊缝受力性能分析

Study on Mechanical Behavior of Main Weld of Cable Beam Anchorage Structure Considering Welding Residual Stress

赣江特大桥主桥为跨度300 m的双塔混合结合梁斜拉桥,该桥型系首次在高速铁路上应用,主跨的钢混结合梁索梁锚固系统采用新型锚拉板式结构,其结构形式和施工工艺都进行了较大改进。索梁锚固结构采用焊接工艺,锚固位置受力较为复杂,施焊后焊接残余应力较大。为研究该区域主焊缝受力性能,采用有限元软件ANSYS分别建立锚拉板结构的节段模型和主要受拉焊缝的热-结构耦合模型,对该锚拉板结构连接部位进行考虑焊接残余应力下的受力性能分析。结果表明,焊缝中间区域的最大残余应力未达到屈服,其两侧区域的应力值较小而能够承担较大的外力,焊缝的整体处于弹性工作状态,具有一定的安全储备,但是在设计施工与后期运营中应予以特别重视。

The main bridge of Ganjiang River bridge is a double-tower composite-beam cable-stayed bridge with the midspan of 300 m.It is the first time to apply this bridge type into the high speed railway.A new type of tensile anchor plate is used in the cable-beam anchorage zones of the midspan of main bridge.Obviously,the application of new structure must have many problems to be solved.The cable beam anchorage structure adopts welding technology,the stress of anchorage position is more complex,and the welding residual stress is large after welding.In order to study the mechanical performance of the main weld in this area,the finite element software ANSYS was used to establish the segmental finite element model and the thermal structure coupling model of the main tensile weld.The mechanical behaviors of cable-beam anchorage zones were researched considering welding residual stress.The results show that the maximum residual stress in the middle area of the weld does not reach the yield strength of the steel,the stress value of the two sides of the weld is small and can bear large external force.The whole welding seam is in elastic working state and has certain safety reserve,but it should be paid special attention in the design,construction and later operation.