Component method and numerical investigation on the initial rotational stiffness of fillet welded rectangular hollow sections (RHS) T-joints

The initial rotational stiffness of the joint has a significant effect on the distribution of internal forces between the members. However, the original component method for calculating the initial rotational stiffness of fillet welded RHS T-joints does not consider the effect of fillet welds, which often results in an underestimation of the initial rotational stiffness. Therefore, in this paper, a modified component method based on the original component method is proposed to calculate the initial rotational stiffness of the joint, which focuses on the effect of the fillet weld size. The modified component method is compared with the original component method and tests to verify its reliability. Subsequently, parametric analyses were performed using the validated numerical model. The results show that (1) the mean value of the ratio of the initial stiffness of the joint calculated by the modified component method to the test value is 1.03, and the COV is 0.014. For the original component method, the mean value of the ratio is 0.72, and the COV is 0.018. (2) The initial rotational stiffness of the joint increases with the increase of the fillet weld throat thickness, chord thickness, and brace-to-chord width ratio (β), and the modified component method and the numerical simulation results are in good agreement. In conclusion, this paper's modified component method is more accurate and has better prediction performance than the original component method.