Nuclear Engineering and Design 269 (2014) 240–249 Contents lists available at ScienceDirect Nuclear Engineering and Design jo u r n al hom epa ge: www.elsevier.com/locate/nucengdes Steel-plate composite (SC) walls for safety related nuclear facilities: Design for in-plane forces and out-of-plane moments Amit H. Varma a,∗ , Sanjeev R. Malushte b , Kadir C. Sener a , Zhichao Lai a a Bowen Laboratory, School of Civil Engineering, Purdue University, West Lafayette, IN, USA b Bechtel Power Corporation, Frederick, MD, USA a b s t r a c t Steel-concrete (SC) composite walls being considered and used as an alternative to conventional reinforced concrete (RC) walls in safety-related nuclear facilities due to their construction economy and structural efficiency. However, there is a lack of standardized codes for SC structures, and design guidelines and approaches are still being developed. This paper presents the development and verification of: (a) mechanics based model, and (b) detailed nonlinear finite element model for predicting the behavior and failure of SC wall panels subjected to combinations of in-plane forces. The models are verified using existing test results, and the verified models are used to explore the behavior of SC walls subjected to combinations of in-plane forces and moments. The results from these investigations are used to develop an interaction surface in principle force (S p1 –S p2 ) space that can be used to design or check the adequacy of SC wall panels. The interaction surface is easy to develop since it consists of straight line segments connecting anchor points defined by the SC wall section strengths in axial tension, in-plane shear, and compression. Both models and the interaction surface (for design) developed in this paper are recommended for future work. However, in order to use these approaches, the SC wall section should be detailed with adequate shear connector and tie bar strength and spacing to prevent non-ductile failure modes. © 2013 Elsevier B.V. All rights reserved. 1. Introduction Safety-related nuclear facilities, for example, nuclear power plants have complex structural layouts and plans with multi- ple compartments for the steam generators, pressurizers, reactor cavity, refueling water storage, or spent fuel pool storage. The compartment walls have large thicknesses (24–60 in.) to provide radiation shielding, and are expected to serve as the primary lateral force resisting systems during seismic events. These compartment walls are also expected to resist the pressures and elevated tem- peratures resulting from postulated pipe-break (accident loading) scenarios. Reinforced concrete (RC) walls have been conventionally used for the compartments of safety-related nuclear facilities. They are designed in accordance with ACI 349 (ACI, 2006) code pro- visions as approved by the NRC staff. The RC walls typically consist of curtains of orthogonal grids of rebar with adequate tie or stirrups (as needed) connecting the rebar grids together. As per ASCE 43-05 (ASCE, 2005), safety-related nuclear facilities are classified as seismic design category (SDC-5), and designed to achieve annual mean frequency of onset of significant inelas- tic deformation (FOSID) of 1 × 10 -5 for safe shutdown earthquake (SSE) level loading. This also corresponds to performance limit ∗ Corresponding author. Tel.: +1 765496 3419. E-mail addresses: ahvarma@purdue.edu (A.H. Varma), smalusht@bechtel.com (S.R. Malushte), ksener@purdue.edu (K.C. Sener), laiz@purdue.edu (Z. Lai). state D, corresponding to essentially elastic behavior, for SSE level loading. Steel-concrete composite (SC) walls typically consist of (0.25–1.5 in. thick) steel faceplates acting composite with (18–60 in.) thick concrete infill. The steel faceplates are typi- cally attached to the concrete infill using (0.5–0.875 in. diameter) steel headed shear studs. Additionally, the opposite steel faceplates are connected to each other (through the concrete) using steel tie bars or shapes of different sizes and spacing. The steel faceplates are designed to act as formwork for placing the concrete, and also to serve as the primary reinforcement after the concrete sets. The steel headed shear studs are designed to provide composite action and connectivity between the steel plates and the concrete infill. The tie bars or shapes are designed to provide structural integrity (resistance to section splitting failure) and out-of-plane shear reinforcement. SC walls are being considered for the next generation of nuclear power plants, and safety-related nuclear facilities because of their potential impact on reducing the construction schedule through modularization. The steel systems consisting of the faceplates and tie bars can be modularized and fabricated efficiently in the shop or at on-site module production facilities. These steel systems act as formwork for placing the concrete, which can potentially reduce the construction schedule by 25% (Braverman et al., 1997). Cur- rently, SC walls are being used as the primary and secondary shield walls of containment internal structures, and in some cases they are being used as the primary shield building for nuclear power plants (DCD, 2011, 2012). 0029-5493/$ – see front matter © 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.nucengdes.2013.09.019