Moment–rotation response of post-tensioned self-centring beam–column connection

Abstract

In order to overcome common problems such as low stiffness, insufficient ductility and enormous residual displacements in beam–column connections, a steel beam–column connection equipped with high-strength strands was developed. These so-called post-tensioned (PT) steel connections consist of high-resistance strands passing parallel to the beam web and through drilled holes in the column flange and the top and bottom beam angles, which act as energy dissipation elements. The displacement and rotation of connections in earthquake events is a problem that can be avoided by a self-centring feature of steel PT connections. In this research, the cyclic response of PT beam–column steel connections with stiffeners connected to the top and bottom beam angles was investigated. Different stiffener geometries and thicknesses were examined and numerical models were simulated using Abaqus software. The results showed that installation of stiffeners on the top and bottom beam angles had a direct effect on the gap opening of the beam–column interface and reduced the relative rotation. Under large applied drifts, primary elements of the connection experienced large deformation and failure. Thus, by equipping angles with stiffeners, all of the induced stresses and damage will be concentrated in the stiffeners. In all the models equipped with stiffeners, the behaviour of beam reached the plastic phase and the minimum value of Mmax/Mpn was almost 1·1. Failure of the angles was also delayed and the primary elements of the connection (beam and column) remained undamaged.