Nuclear Engineering and Design 236 (2006) 993–1002 Non-linear response of reinforced concrete containment structure under blast loading A.K. Pandey a , Ram Kumar b,∗ , D.K. Paul c , D.N. Trikha d a Central Building Research Institute, Roorkee, India b Bridge and Structures, Central Road Research Institute, New Delhi, India c Department of Earthquake Engineering, IIT Roorkee, Roorkee, India d Structural Engineering Research Centre, Ghaziabad, India Received 11 April 2005; received in revised form 15 September 2005; accepted 16 September 2005 Abstract The paper demonstrates the effect of an external explosion on the outer reinforced concrete shell of a typical nuclear containment structure. The analysis has been made using appropriate non-linear material models till the ultimate stages. The generation and the propagation of blast wave and its effect on a cylindrical structure are discussed. Parametric studies have also been performed for surface detonations of different amount of blast charges at a distance of 100m from a nuclear containment shell. Critical distances have been evaluated for different amount of blast charges for nuclear containment shell. © 2005 Elsevier B.V. All rights reserved. 1. Introduction Nuclear containment structure in many countries is a dou- bly shell envelope consisting of a primary inner pre-stressed concrete containment shell with an outer reinforced concrete shell. Studies are reported in literature (Rebora and Zimmerman, 1976; Crutzen et al., 1981; Cervera et al., 1987; Abbas, 1992) on the impact of an aircraft on the outer reinforced concrete nuclear containment shells, but the studies are rather scarce on the effect of explosions on the containment shells. The present study has therefore been directed to study the effect on external explosions on a typical outer reinforced concrete containment structure. Prediction of response of concrete structures for blast loading requires three-dimensional structural idealization, true modeling of the material non-linearities and precise modeling of the blast phenomenon. Different aspects of non-linearity in concrete, e.g. pressure sensitivity in three-dimensional loading situations, strain rate sensitivity in dynamic loading situations and cracking of concrete in tension have been included in devel- oping a finite element software and different parametric analysis has been performed. ∗ Corresponding author. Computer simulation of the blast loading parameters for a specified amount of blast charge for a cylindrical structure like nuclear containment shells is very important in precise deter- mination of the response. Most parameters for modeling the blast shock interaction are required in the form of equations and therefore such equations as available for different parameters have been expressively stated. The response of the outer rein- forced concrete shell is studied subjected to different amounts of blast charges at varying distances. The structural response has been presented in terms of the extent of cracking in the concrete, stress in steel and concrete after yielding and deflections. Some useful conclusions have been drawn on the basis of the study. 2. Mathematical modeling and formulations In order to analyze the behavior of reinforced concrete con- tainment shells under blast loading (high rate of loading), proper choice of the element to model concrete and reinforcement real- istically, numerical integration scheme to obtain required degree of accuracy and computational efficiency and appropriate non- linear material models are required. Pandey’s model (2001) of an embedded bar in a brick element ensuring full strain compat- ibility between the steel and concrete with a strain rate depen- dent constitutive relationship for concrete and steel including 0029-5493/$ – see front matter © 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.nucengdes.2005.09.015