Behaviour of short columns made with conventional or FRP-confined rubberised concrete: An experimental and numerical investigation

Abstract

Failure of short columns in concrete buildings has been extensively reported during past earthquakes. Assessing the behaviour of short columns is challenging and often requires using time-consuming advanced numerical modelling. This article presents a new and practical Short Column Macro Element (SCME) that predicts accurately the behaviour of concrete short columns. A 1/3-scale one-storey building with short columns is subjected to lateral loading tests until failure. The experimental results from the building are then used to calibrate a numerical model in Abaqus®. It is shown that the numerical model matches well the experimental results. The experimental crack patterns and stress distribution from Abaqus® are then used to determine the load path within the short column. Based on these data, a new strut-and-tie SCME is proposed and implemented in OpenSees software to simulate accurately (within 5% accuracy) the behaviour of the short columns of the tested building. Subsequently, the frame models calibrated in OpenSees and Abaqus® are modified to examine numerically the effectiveness of highly deformable FRP-confined rubberised concrete (FRP CRuC) at increasing the deformability of short columns with different levels of FRP confinement (1, 2 or 3 layers). The numerical results show that whilst the tested building failed at a small displacement of 5.4 mm (0.43% drift ratio), the use of FRP CRuC short columns with minimal confinement (1 layer of AFRP only) increased the building’s displacement by almost seven times to 37 mm (3.0% drift ratio). This also enabled more redistribution of forces to other structural members of the building. This article contributes towards the development of practical design/analysis models for short columns made of conventional concrete and FRP CRuC, which are scarce in the existing literature.