Compressive stiffness of L-stubs in contact with rigid and flexible foundations

Abstract

The rotational stiffness of bolted connections is influenced by the stiffness of T-stubs loaded in tension. Except for column base plate, the stiffness of T-stubs loaded in compression is assumed infinite and the centre of compression is fixed at the centre of the beam flange. Nevertheless, this assumption leads to inconsistent conclusions for bolted circular flange connections, double web angle connections… The relative stiffness of the tensile and compressive areas should be considered. Simple expressions of the compressive stiffness of L-stubs and T-stubs have been derived recently based on refined beam model in contact with a rigid foundation. However, the end-plate can be in contact with a flexible foundation. In the present paper simple analytical expressions are proposed to calculate the compressive stiffness of L-stubs in contact with rigid or flexible foundations. For this purpose, a refined beam model resting on Winkler foundation is firstly derived. Then, this model is used to analyse L-stubs in contact with flexible or rigid supports. Simplifications are proposed for the contact pressure distribution and also the compressive stiffness. The analytical propositions are compared against finite element calculations performed with ANSYS APDL.