Effects of Welding on the Tensile Performance of High Strength Steel T-stub Joints

In this study, the effects of welding on the tensile performance of the Reheated, Quenched and Tempered (RQT) S690 high strength steel T-stub joints are investigated by both experimental and numerical methods. Firstly, six RQT-S690 T-stub joints as well as two Thermal-Mechanical Controlled Processed (TMCP) S385 T-stub joints are fabricated and tested. The results are validated against the design plastic resistance equations provided by EC3. It is found out that EC3 predicts the plastic resistance of the TMCP joints conservatively, but tends to overestimate that of the RQT-S690 joints although the latter is much superior. It is deducted that the problem may come from the compromised properties of the heat affected zone (HAZ) at the weld toe. Further, finite element analysis is carried out to investigate the effects of property alteration in the HAZ on the tensile performance of the RQT-S690 T-stub joints. It is shown that the models with welding simulation agree well with the test results, while the models without considering the welding effects predict the load carrying capacity unconservatively when the displacement increases.