ABSTRACT

Designers are often required to assess the fatigue performance of hollow section joints by considering the stress levels at potential crack locations. In these types of jOints, the flexibility of the walls of rectangular members leads to additional bending stresses developing which depend upon the ratios of member sizes connected. In considering the structural behaviour of RHS connections, also, it is necessary to consider all relevant modes of failure. Burdekin et al (1989) carried out an investigation into the fatigue behaviour of square hollow section double Tjoints, they found that for the fillet weld sizes used, the mode of failure changed from failure by fatigue through the fillet weld throat for high ~ ratios of ~ = 0.65, to failure by fatigue cracks at the fillet weld toe for lower values of ~ = 0.39. The best fatigue design methods available require knowledge of the stress concentration factors due to bending of the walls at the weld toe position, and knowledge of the stresses in the welds themselves.