Structural Evaluation of Sustainable Orthotropic Three-dimensional Sandwich Panel System

This study aims at evaluating the static and cyclic behavior of Expanded Polystyrene (EPS) sandwich panels used as both structural and non-structural members. The study involved both theoretical modeling and large-scale experimental verification tests of various structural elements. The ultimate goal of the proposed study is to fill the existing gap resulting from a lack of both systematic analytical and numerical procedures for predicting the behavior of these sandwich panels. A comprehensive experimental program was designed and executed that covers different loading scenarios, aspect ratios and reinforcements of floor and roof slabs, beams, as well as bearing and shear walls. Based on the results of this study, simplified, yet effective, design procedures following the American Concrete Institute (ACI 318) principals were developed for predicting the flexural behavior of sandwich floors and slabs. In addition, and based on the observed flexural failure modes, recommendations for minimum additional hot-rolled steel reinforcement was established and verified by results of large-scale tests. The major bulk of the experimental phase was devoted to analyze and evaluate the structural behavior of sandwich shear walls due to the absence of reliable experimental information. In the experimental phase, different parameters affecting the behavior of sandwich walls were evaluated to identify the impact of each parameter on the overall behavior of sandwich walls including strength, ductility and stiffness. These parameters included: (i) application methods of structural mortar, (ii) mortar compressive strength, (iii) wall aspect ratio (AR) (iv) simultaneous application of gravity load on cyclic shear wall behavior, and (v) the effect of introducing openings. A reliable procedures was developed for predicting in-plane wall displacement regarding both flexural and shear deformations and results were similar to those from the large-scale tests. Based on the experimental results, a simplified procedure was developed to determine an average value for the Seismic Modification Factor (R) that was found to be 3.50 for walls with aspect ratios (AR) equal to 1.0 and 5.0 for walls with aspect ratios equal to 0.75. Recommended values for both System Over-Strength Factor (ohm0) and the Deflection Modification Factor Cd were found to be 3.0 and 3.5, respectively. The numerical modeling was performed using ABAQUS Finite Element Modeling (FEM). Both linear and non-linear analyses were performed with very good correlation between the numerical and experimental results achieved.