焊接热影响区断裂性能试验研究

钢框架梁柱节点在最近几次地震中经历了大量断裂破坏现象。可以采用杆端非线性弹簧模型对这种破坏模式进行数值模拟。为了确定断裂分析模型的参数，本文进行了结构钢（Q235c,Q345c)焊接热影响区断裂性能试验研究，获得了两种材料在焊接热影响区的JR阻力曲线。通过比较不同的断裂准则，考虑了裂纹失稳扩展前的稳态裂纹累计，根据J积分撕裂模量法建立了裂纹失稳的失效评定图。采用两种材料分别制作了一组外形尺寸一致，初始裂纹尺寸不同的单边裂纹焊接板，测出相应的极限拉伸应力，并和理论曲线进行了对比。最后，对于本文研究结果的适用范围做了说明。

Experimental Research on Fracture Performance in Weld Heat-affect Zone

Many fractures at the beam-to-column joints of steel frames were found in the recent earthquakes. It's possible to introduce a model, which is composed of several elasto-plastic axial springs at the end of bars, to simulate this failure mode of joints. In order to calibrate the parameter of analytic fracture models, the experimental research of fracture performance in the weld heat-affect zone was done. The relationship curve between the resistance J integral and the value of crack extension was plotted by the test. The failure assessment diagram of instability of crack propagation was also obtained after the comparison of some fracture criteria, which considered the accumulation of crack propagation before loosing its stability. The utmost tensile intensity of a group of welded single-edge-crack plate made of Q235 or Q435c, which were same shape and different initial crack length, was obtained and compared with the theoretic curve. At last, the applying range of the research results was illustrated.