دانلود رایگان مقاله اثر جوش بر عملکرد کششی فولاد اتصالات T با استحکام بالا

ABSTRACT

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 RQTS690 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. © 2016

4. Conclusions

This study investigated the effects of welding on the tensile performance of the Reheated, Quenched and Tempered (RQT) S690 high strength steel T-stub joints in two phases. The first phase experimentally investigates the tensile behavior of six RQT-S690 T-stub joints, and the Thermal-Mechanical Controlled Processed (TMCP) steel in grade S385 is also tested with same program as control material. By comparing the load-displacement curves, it is found that the behavior of these two material is of the same pattern. The EC3 design resistance prediction equations predict the first yield resistance of the TMCP-S385 specimens conservatively, but seem to overestimate that of the RQT-S690 joints. Further discussion deducts that the problem may come from the compromised properties of the plastic hinges at the weld toe, which is highly possible to be affected by welding heat input. Phase II of this study verifies this deduction by finite element analysis. It is shown that 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. Finally, it is concluded that welding has significant impact on the strength of high strength steel RQT-S690 T-stub joints.Without considering this impact would lead to overestimation on the load carrying capacity and may be unsafe.