Thermo-Mechanical Behaviour of a New SIP Wall Under Axially Compressive Load

Abstract

This study examines experimentally and numerically the thermo-mechanical behaviour of a novel Structural Insulated Panel (SIP) wall. The SIP UWall comprises of external cement boards and an internal core of expanded polystyrene and foamed concrete. Thermo-structural panels of size 600 × 2400 mm were first exposed to temperatures of up to 70 °C and flexo-compression to examine experimentally the behaviour of the novel SIP UWall vs traditional wall systems used in Southeast Asia, such as mon block walls, brick block walls, and lightweight block walls. The results indicate that the deflection of the SIP UWall was 42.0%, 23.8%, and 16.4% lower than that of traditional mon block, brick block, and lightweight block walls, respectively. To further assess the thermal performance of the above walls under real environmental conditions, four scale-down house units (1.5 × 1.5 × 2.4 m) were built in Chachoengsao province, Thailand. Results from the four scaled-down house units show that the use of SIP UWall reduced indoor temperatures by up to 5 °C compared to units constructed with mon block walls. Subsequently, the study proposes a novel approach to assess the thermo-mechanical behaviour of the panels using Fourier's law of heat transfer, Airy's stress function, and the principle of conservation of energy. The new approach explicitly considers the combined effect of applied thermal and mechanical loads. The approach is validated using the results obtained from the panel tests and the scale-down house units. It is shown that the proposed semi-empirical approach predicts well the thermo-mechanical behaviour on the wall panels tested in this study, with a Prediction/Experiment ratio of 1.06 and a Standard Deviation of 0.12. The tested wall panels and scaled-down hose units are subsequently modelled in Abaqus®. The results indicate that the SIP UWall exhibited superior thermal performance in terms of heat absorption, surpassing the mon block, brick block, and lightweight block panels by 19.4%, 15.7%, and 10.8%. The small errors in the Abaqus® predictions (always < 5%) indicate that the modelling approach adopted in this study was sufficiently accurate to simulate the thermal behaviour of the tested wall panels. This study contributes towards developing better assessment models and more energy-efficient construction materials in Southeast Asia.