Effect of welding residual stress on the performance of CFST tubular joints

Abstract

The residual stress and the dimensional distortion due to rapid temperature variation during the welding process are often crucial for the life-cycle behavior of structures, especially for key connection regions in offshore and marine applications. This paper evaluates the detailed welding effects on the strength and stiffness of concrete-filled steel tubular (CFST) Y- and K-joints using advanced finite element modeling (FEM), and the results are then validated and compared with collected test data. A prescribed temperature approach, Abaqus Welding Interface (AWI) and a tailored shell-solid modeling technique are adopted to facilitate the simulation of welding heat generation as well as the associated residual stress. The results are then implemented into the numerical models before defining boundary and loading conditions according to related tests for careful validation and full-range analysis. With the help of the established advanced modeling technique, the accuracy of the predicted stiffness for CFST Y- and K-joints is greatly improved. Parametric study indicates that the brace to chord thickness ratio stands out as a governing factor in the joint failure. The joint strength and stiffness decrease moderately when the weld leg thickness is reduced, whilst a lower and smaller region of residual stress is induced.