钢桁梁桥主桁杆件厚板焊接残余应力空间分布试验研究

Experimental Study on Welding Residual Stress Spatial Distribution in Thick Plate for Main Member of Steel Truss Bridge

为研究某钢桁梁桥主桁杆件钢厚板焊接残余应力的空间分布规律,采用与实桥相同的材料和焊接工艺制作30 mm厚的对接焊试板,用局部逐层去除盲孔法对试板表层及内部残余应力进行测试,并对测量结果进行不确定度评定。试验结果表明:厚板表面焊接残余拉应力峰值位于焊缝附近区域,残余应力呈典型的拉-压分布趋势;内部横向残余应力在焊缝附近的分布状态为外拉内压,并且在上表层具有较大的应力梯度;内部纵向残余应力在焊缝附近为拉应力;随着距焊缝中心线距离的增加,纵横向残余应力皆开始逐渐减小,直至转变为压应力。

In order to study the spatial distribution of welding residual stress in the thick steel plate for the main member of a steel truss bridge, the 30 mm thick butt welded specimen plate was fabricated with the same material and welding process as the real bridge. The local material removal blind hole method was used to measure the surface and internal residual stresses and the uncertainty of the measurement results was evaluated. The results indicate that the peak value of the surface welding residual stress is located in the weld region and its vicinity. The typical trend of the surface residual stress is tensile-compressive distribution. The internal transverse residual stress has a high stress gradient near the upper surface while the transverse residual stress tends to be tensile near the surface and compressive on the internal plate in the vicinity of the welding region. The internal longitudinal residual stress is tensile in the region near the welding bead. With the increase of the distance from the center line of the welding bead, both longitudinal and transverse residual stresses are found to decrease gradually until they are transformed into compressive stresses.