Mechanical performance of elliptical one-sided bolted joints for T-stub and hollow section members under tension

Abstract

This paper presents experimental and numerical investigations on the tensile performance of the elliptical one-sided bolted joints in building applications. Two types of joints are examined including the T-stub joints and T-hollow joints, where T-stub joints are formed by two T-stubs connected together through elliptical one-sided bolts at their flanges; and T-hollow joints are formed by two T-stubs connected to a square hollow section (SHS) member with the help of the elliptical one-sided bolts. A group of T-stub joints with ordinary bolts is also comparatively studied. Similar failure modes were observed for either elliptical one-sided or ordinary bolted joints while the yield capacity for elliptical one-sided joints was 9% lower than that of ordinary bolted joints for the T-stub joints. Parametric studies are further carried out on the key parameters such as flange thickness of the T-stubs and wall thickness of the hollow section members in the T-stub and T-hollow joints. It is found that the joint stiffness and strength can be improved with the increase of flange thickness or wall thickness for T-stub and T-hollow joints. Analytical models based on the yield line mechanisms are then presented, providing mechanism-based understanding for such elliptical one-sided joints in structural assembly. Detailed finite element (FE) models were constructed with considerations of bolt pre-tensioning and contact behaviours such as those between T-stub flange and bolt head. The deformed configurations of specimens can be successfully described by the FE modelling and the differences on initial stiffness and yield capacity between experimental and FE results are within about 10%.