Iterative and Simplified Sandwich Beam Theory for Partially Composite Concrete Sandwich Wall Panels

Abstract

This paper presents an iterative sandwich beam theory (ISBT) and a simplified version suitable for the design termed simplified sandwich beam theory (SSBT) used to predict the elastic mechanics of partially composite insulated concrete sandwich wall panels (SWPs) under flexural, axial, and thermal loads. These solution methods expand upon closed-form solutions to create a more general analysis technique. Design and analysis of SWPs are handled largely outside of codified documents and are almost exclusively designed such that they will remain within the elastic range. The presented ISBT and SSBT methods have been used in the United States precast industry since 2017 and are implemented in widely available software, LECWall, as of 2020, for predicting elastic deflections and stresses. In this paper, the ISBT and SSBT solution methods are validated with experimental data from the literature and using finite-element analysis. For the ISBT cracking moment and deflection, the measured-to-predicted ratio were 0.99 and 1.0 with coefficients of variation (COVs) of 0.10 and 0.11, respectively. For the SSBT cracking moment and deflection, the measured-to-predicted ratio was 0.99 and 0.99 with COVs of 0.21 and 0.19, respectively. For thermal loading, the ISBT and SSBT deflection m easured-to-predicted ratios were 0.95 and 0.90, respectively. The model was then used to investigate the behavior of sandwich wall panels under varying load combinations and with various section and material properties to demonstrate the robustness of the presented methods.