Numerical study and Generalised Component Method for predicting full-range behaviour of bolted steel connections

Abstract

This thesis examines the behaviour of bolted steel connections, with a particular focus on their fullrange nonlinear behaviour. The research addresses design and assessment issues at both the component and connection levels, with a specific interest in the “Geometrically and Materially Nonlinear Analysis with Imperfections” (GMNIA) framework. At the component level, the thesis conducted experimental investigations on lap joints and angle cleats to study the full-range behaviour of three important connection components, i.e., “bolts in bearing”, “plate in tension” and “angle cleat in bending”. Finite element (FE) models were developed to simulate the tested components, incorporating two “local” fracture criteria with the parameters calibrated by the tested coupons. Based on the experimental results and FE analysis, improved mechanical models (spring models) were developed to predict the force-displacement behaviour of three important components, i.e., “bolts in bearing”, “angle cleat in bending”, and “T-stub in bending”. At the connection level, the study employed both FE and mechanical models (Component Method) to study the connection’s full-range action-deformation behaviour. An empirical method for calibrating fracture parameters was proposed to reduce the number of coupon tests while still providing reasonable evaluation of the fracture properties. The mechanical models of complete connections are developed in the context of the Generalised Component Method (GCM).The proposed mechanical models in the component level are incorporated with the GCM to predict the full-range moment-rotation curves of three representative bolted steel connections. This study developed a new GCM model for bolted bearing type connections to capture the full-range connection response and all relevant limit states, including the bolt shear, bearing, shear-out, net section fracture, and block shear limit states.