Effect of reinforcement on the response of concrete panels to impact of hard projectiles Mohamed Abdel-Kader a, * , Ahmed Fouda b a Obour High Institute for Eng. and Tech., Cairo, Egypt b Engineering Consultant Office, Egyptian Armed Forces, Egypt article info Article history: Received 14 March 2013 Received in revised form 14 July 2013 Accepted 16 July 2013 Available online 25 July 2013 Keywords: Impact Perforation Projectile Concrete Reinforcement abstract The impact of a hard projectile on a concrete target is a complex incident which cannot be described accurately without giving consideration to the effects of the different variables involved and to the associated physical phenomena. Among these variables are the reinforcement details in the concrete target. In this paper the response of 26 concrete specimens, with 500  500  100 mm 3 dimensions, to an impact of 23 mm, 0.175 kg hard projectiles was examined in an experimental study. The tests were planned with an aim to observe the influence of the ratio and type of reinforcement (embedded rebar mesh or steel plate lining) on the performance of concrete under this type of loading. The variants that were examined were the location of reinforcement mesh and steel plate lining (front, rear, and both front and rear). The main findings show that the location of the reinforcement mesh affects the front and rear face craters. Also lining concrete target with front and rear steel plates has positive effect on the perforation resistance. Ó 2013 Elsevier Ltd. All rights reserved. 1. Introduction A large amount of laboratory tests had been conducted [1e4] to study the local effects of the impact of a hard projectile on a con- crete target. Some variables affecting impact are related to pro- jectile, such as projectile mass, diameter, nose shape and impact velocity. Other variables are related to concrete target, such as thickness, density, concrete compressive and tensile strength, strain rate effects on concrete strength and reinforcement ratio and details such as rebar diameter and spacing [5]. When projectile strikes concrete target with certain velocity, one or more of the common seven modes of impact results [1,4,6] may occur, Fig. 1 . The penetration depth is the distance x a projectile penetrates a target without resulting in perforation and scabbing. The scabbing limit h s is the target thickness that is just enough to prevent the scabbing, scabbing occurs when the target thickness H o < h s . The perforation limit e is the minimum thickness of the target to prevent the perforation. The ballistic limit (perforation velocity) V p is the impact velocity at which the projectile perforates the target with zero exit velocity. In plain concrete mainly the strength dominates its ability of resisting penetration, while reinforced concrete may be influenced by both the concrete strength and the amount of reinforcement, also the shape and depth of the craters may depend on the layout and embedding depth of reinforcing meshes [7]. It was concluded that the concrete tensile strength is a better parameter to describe its resistance against impact punching [8,9]. And since the rein- forcement is an important component of the mechanisms that produce the tensile capacity of reinforced concrete, it was further concluded that the perforation resistance is also influenced by the amount of the reinforcement [10]. The other factors, such as ma- terial properties, diameter of reinforcing bars, reinforcement mesh size and space, also possibly affect the final results of penetration/ perforation [7,11]. In the penetration tests presented by Sliter [2], Hanchak et al. [12], Dancygier [13] and Dancygier et al. [14] it was shown that light or moderate reinforcement has little effect on penetration and scabbing, while very heavy reinforcement im- proves only perforation resistance. Most of the published empirical formulae for local damage phenomena (i.e. penetration, perforation and scabbing) does not explicitly account for the amount of reinforcement [6,15e17], although considerable experimental results came from the impact tests of reinforced concrete [7]. The effect of steel bar reinforcement * Corresponding author. Tel.: þ20 01001212803; fax: þ20 2 24973150. E-mail addresses: kadermoh@hotmail.com (M. Abdel-Kader), Foda_eng@ hotmail.com (A. Fouda). Contents lists available at ScienceDirect International Journal of Impact Engineering journal homepage: www.elsevier.com/locate/ijimpeng 0734-743X/$ e see front matter Ó 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.ijimpeng.2013.07.005 International Journal of Impact Engineering 63 (2014) 1e17