Finite element modeling of steel-plate concrete composite wall piers Siamak Epackachi a,⇑ , Andrew S. Whittaker a , Amit H. Varma b , Efe G. Kurt b a Dept. of Civil, Structural and Environmental Engineering, University at Buffalo, NY, United States b School of Civil Engineering, Purdue University, West Lafayette, IN, United States article info Article history: Received 16 February 2015 Revised 6 May 2015 Accepted 12 June 2015 Keywords: Steel-plate composite shear wall Infill concrete Steel faceplate Cyclic loading Hysteresis loops Numerical modeling LS-DYNA abstract A finite element model is developed in LS-DYNA to simulate the nonlinear cyclic response of flexure-critical steel-plate concrete (SC) composite shear walls. The developed finite element model is validated using data from tests of four large-scale SC wall piers with an aspect ratio (height-to-length) of 1.0. Each SC wall was constructed with steel faceplates, infill concrete, steel studs and tie rods, and a steel baseplate that was post-tensioned to a reinforced concrete foundation. Steel studs tied the face- plates to the infill concrete and the infill concrete to the baseplate. Damage to the SC walls included cracking and crushing of the infill concrete and yielding, outward buckling and tearing of the steel face- plates. The finite element predictions include global force–displacement responses, equivalent viscous damping ratio, damage to the steel faceplates and infill concrete, strain and stress distributions in the steel faceplates, and estimates of the contribution of the steel faceplates and infill concrete to the lateral resistance of the walls. The DYNA-predicted responses are in good agreement with the measured responses. The impacts of interface friction between the steel faceplates and the infill concrete, and of the distribution of shear studs on the baseplate, to the global response of the SC walls are investigated using the validated DYNA model. Ó 2015 Elsevier Ltd. All rights reserved. 1. Introduction Steel-plate concrete (SC) composite walls, consisting of steel faceplates, infill concrete, headed steel studs anchoring the face- plates to the infill, and tie rods connecting the two faceplates through the infill (see Fig. 1), have potential advantages over con- ventional reinforced concrete and steel plate shear walls in terms of constructability and seismic performance. However, these SC walls have not been used for earthquake-resistant building construction, in part because there are little data on their seismic performance at deformation levels expected in maximum consid- ered earthquake shaking, aside from the experiments of Zhao and Astaneh-Asl [48], Eom et al. [12], and Nie et al. [25]. The seismic response of an SC wall is influenced by the nonlin- ear cyclic responses of the steel faceplates, the infill concrete, bond between the steel faceplates and the infill concrete, and the con- nectors (studs and tie rods). Analysis that assumes perfect bond between the steel faceplates and infill concrete, and ignores the effects of friction between the steel and concrete and connector spacing will generally not accurately simulate the behavior of SC walls (e.g., [46]). The connections of an SC wall to adjacent elements, SC and/or reinforced concrete (RC), or to a foundation, must be considered in the development of a finite element model because they provide sources of flexibility that could substantially influence global response. This paper describes the nonlinear finite element modeling of SC wall piers using the general-purpose finite element code LS-DYNA [23,24]. The models are validated using data from tests of four large-scale SC walls. The effects of steel material model, friction between steel and concrete, studs and tie rods embedded in the infill concrete, concrete cracking and crushing, buckling and tearing of the steel faceplates, and foundation flexibility are considered. 2. Literature review Ozaki et al. [29] conducted an analytical and experimental study on steel-plate reinforced concrete panels subjected to cyclic in-plane shear loading. The experimental study investigated the effect of steel faceplate thickness, axial load, partitioning webs, and penetrations on global response. Finite element models were developed to predict the pre-peak response of the SC panels, including those with openings. Vecchio and McQuade [42] applied the Distributed Stress Field Model (DSFM) to SC walls subjected to axial load, in-plane shear, and the reversed cyclic lateral http://dx.doi.org/10.1016/j.engstruct.2015.06.023 0141-0296/Ó 2015 Elsevier Ltd. All rights reserved. ⇑ Corresponding author. E-mail address: siamakep@buffalo.edu (S. Epackachi). Engineering Structures 100 (2015) 369–384 Contents lists available at ScienceDirect Engineering Structures journal homepage: www.elsevier.com/locate/engstruct