RESILIENT INFRASTRUCTURE June 1–4, 2016 STR-885-1 FINITE ELEMENT MODELLING OF COMPOSITE HOLLOWCORE SLABS Aiham Adawi Western University, Canada Maged A. Youssef Western University, Canada Mohamed E. Meshaly Alexandria University, Egypt ABSTRACT Hollowcore slabs are commonly used for floor and roofs of residential and commercial buildings. Concrete topping, which is commonly cast for leveling purposes, can also be used to increase the load capacity of hollowcore slabs. The post-cracking behaviour of hollowcore slabs greatly affects their ultimate strength. The composite action adds another level of nonlinearity. This paper presents a comprehensive 3-D finite element model that can predict the behaviour of such composite slabs. Nonlinear springs were used to model the interface layer. The nonlinear material behaviour of the concrete and the prestressing strands were also accounted for. Innovative analysis technique to simulate the staged construction of composite hollowcore slabs is also presented. The proposed analysis is validated using results from a previous experimental study by the authors. Keywords: hollowcore slabs, composite behaviour, interface properties, 3-D nonlinear finite element analysis. 1. INTRODUCTION The vast majority of previous literature on the composite action of flexural elements is related to steel beams, where the concrete topping is attached to the top flange of the steel beam using shear connectors. In such cases, the connectors (shear studs) can be modeled using spring elements (Salari et al., 1998; Queiroz et al., 2006). The stiffness (force-displacement curve) of those springs is usually evaluated through series of push-off tests. Deng (2012) provided a modeling technique that accounted for the behaviour of shear studs in composite prestressed concrete girders and composite steel girders. Number of researchers successfully modeled non-composite hollowcore slabs using finite element analysis. To the authors’ knowledge, there is a lack of nonlinear numerical models in the area of composite hollowcore slabs. Mones (2012) conducted multiple push-off tests on composite hollowcore slabs with different surface finishes. Mones (2012) also modeled the composite behaviour of hollowcore slabs using 2-D plane-stress elements. Spring elements resembled the interfacial shear stress. The analysis assumed linear-elastic behaviour and did not account for the peel behaviour. The shear stiffness of the spring elements was determined based on the results of the push-off tests, which resembled a state of pure shear. Results of the finite element analysis were not validated. The behaviour of the concrete material becomes highly nonlinear after cracking, which greatly affects its overall response. Therefore, it is necessary to investigate the behaviour of composite hollowcore slabs in the post-cracking zone. This paper presents a 3-D nonlinear finite element model for a composite hollowcore slab specimen. The slab was part of a comprehensive experimental program conducted by the authors at Western University, Canada (Adawi et al, 2015). Interface stiffness values obtained from the push-off tests presented by Adawi et al. (2015) were used as initial values in the modeling of the full-scale slab. The final non-linear interfacial shear and peel stiffnesses of the brought to you by CORE View metadata, citation and similar papers at core.ac.uk provided by Scholarship@Western