Behaviour of steel open web joist under geometric nonlinearity

Abstract

This work focuses on a parametric study using theoretical and analytical investigations to determine the geometric nonlinearity response of an open web steel joist under non-uniform bending. To achieve this, a preparatory analysis of three steel design standards used in the creation of various combinations utilizing slenderness ratios was conducted. A total of 40 finite element models were produced using the ABAQUS software, each of which was distinguished based on the slenderness ratio and was modelled using typical linear material characteristics. The open web steel joist's maximum deflection within the elastic limit was evaluated theoretically and compared analytically. The comparison between the load and the final deflection behaviour, which was determined theoretically and analytically, shows excellent collaboration and validates the analytical modelling. The results show that, despite the material's linearity being preserved, load vs. deflection graphs is becoming nonlinear. This demonstrates that geometric nonlinearity significantly affects the final capacity and deflection of open web steel joists. Also, with more sectional depth, geometric nonlinearity has a greater effect. Therefore, this work reveals that while analysing the behaviour of open web steel joists, the effects of geometric nonlinearity must be taken into account.