Finite Element Simulation of FRP Strengthened Reinforced Concrete Slabs Under Two Independent Air Blasts Ganchai Tanapornraweekit*, Nicholas Haritos, Priyan Mendis, Tuan Ngo Department of Civil & Environmental Engineering University of Melbourne, VIC 3010, Australia Received on 17 Feb 2010, Accepted on 19 Aug 2010 ABSTRACT Multiple detonations might occur in both accidental explosions and terrorism attacks. Generally, normal reinforced concrete (RC) structures which are not designed to withstand high intensity blast loads are not capable of withstanding explosions from a single blast let alone a sequence of more than one blast. Since concrete is often highly cracked and damaged from the first blast, the remaining deteriorated concrete and steel reinforcement in a RC member becomes very vulnerable to collapse. This paper reports on the feasibility of using fibre reinforced polymer (FRP) to strengthen a normal RC slab capable of sustaining two independent air blasts. Apart from the experimental investigation, numerical studies have been conducted to verify the concrete and FRP material models when they are utilized to predict the behaviour of FRP-RC structures under multiple blasts. This article provides guidance on how to choose appropriately between the two existing concrete models available in the LS-DYNA code. 1. INTRODUCTION In bomb blast events, most fatalities have resulted from the secondary damage induced on structures close to the explosion sources, e.g. flying shards of glass and concrete debris and also from the ensuing collapse of structures. Continued functionality immediately following a blast event of the infrastructure concerned will allow management authorities to mount rescue attempts, and in the case of an explosion on a highway bridge, to alter traffic paths whilst maintaining a crossing at the bridge location. These desirable requirements give rise to research questions on how to provide adequate redundancy to concrete structures in case they are subjected to terrorism and/or accidental explosions. There have been several attempts to utilize composite material to strengthen structures which might be damaged by explosions [1–7]. Tolba [3] investigated the structural response and ultimate resistance of RC panels with externally bonded carbon fibre (CFRP) and glass fibre (GFRP) laminates subjected to blast load. The test results clearly showed that FRP retrofitted panels performed better than the ordinary RC panels in terms of structural integrity and capability to withstand blast pressure and impulse. There was some peeling of CFRP and GFRP laminates observed in the tests. International Journal of Protective Structures – Volume 1 · Number 4 · 2010 469 * Corresponding author. E-mail addres: ganchai@civenv.unimelb.edu.au