Numerical Study on Post-weld Heat Treatment of Non-stiffened Welded Box-Section Member and Its Compressive Behavior

Weld-related problems such as residual stress and deformation on the performance of the steel structural members are of crucial concerns for not only fabricating the new structures but also repairing the existing structures in the civil engineering industry. The effectiveness of post-weld heat treatment (PWHT) for reducing the residual stress is well known and it is widely applied on the fabrication of the welded members in pressure vessels and pipelines by using a large furnace in a factory. However, there is a need to find an alternative heat source for PWHT applicable for the existing steel structural members on site. In this study, a sheet-type ceramic heater is noted as a portable heat source for PWHT on the existing structural members on site. For investigating the effect of PWHT with the ceramic heater on the residual stress release and the load-carrying capacity of the welded members under the compressive load, a 3D finite element (FE) model considering creep strain properties was developed. The numerical model was verified by comparing with the experimental results on the non-stiffened welded box-section member. The FE model could simulate the compressive behavior of the experimental specimens with PWHT. It provided a good agreement in the residual stress reduction and a resemblance of the out-of-plane deformation with the experimental results. From this fundamental investigation, it was confirmed that the FE model for the PWHT simulation and loading analysis was established.