Behaviour of the lockbolt demountable shear connector under combined shear and tension loading

Abstract

A demountable ‘lockbolt’ shear connector (LB-DSC), consisting of a short partially threaded bolt that is locked on a steel flange to eliminate tolerance and initial slip issues and a compatible machined tube that can be fastened/unfastened over the bolt to facilitate the easy and fast disassembly process for reuse of all components, was proposed for use in composite floors or decks of buildings or bridges. This paper focuses on the numerical investigation of the structural behaviour of the LB-DSC under combined tension and shear loading. A detailed finite element method (FEM) model considering material and contact nonlinearity was built and calibrated based on previous standard pushout tests on the LB-DSC. The calibrated FEM model was used to investigate the effects of various parameters on tensile and shear behaviour of the LB-DSC, including the concrete strength of slab, the bolt diameter and strength, the steel tube thickness, and the presence and strength of infill grout. The shear resistance of the connector is significantly reduced when a tensile force more than 20% of the tensile resistance of the connector is applied. Design equations for predicting the tension resistance and tension-shear interaction are proposed to expand the application of the LB-DSCs in sustainable steel–concrete composite construction.