Shear strength and failure behavior of precast concrete sandwich panels under elevated temperatures: Experimental and numerical investigation

Global warming is causing a continuous rise in global temperatures, which negatively impacts the strength, and durability of concrete structures. Precast concrete sandwich (PCS) structures have become increasingly popular due to their energy efficiency and lightweight properties. However, the mechanical properties of core insulation materials can degrade at elevated temperatures above 50°C due to softening, compromising the overall strength and durability of the structure. This study investigates the shear strength capacity of concrete sandwich panels using double shear (push-out) tests. A total of 14 double-shear specimens were fabricated and tested with varying shear connector spacing. The tests were conducted under ambient conditions and after exposure to elevated temperatures of 50°C and 75°C using a thermal furnace. The results reveal a significant reduction in shear capacity at higher temperatures, primarily due to reduced bond strength between the concrete and insulation material. Additionally, the study examines failure modes of specimens with and without connectors under different temperature conditions. Finite element modeling was utilized to simulate the performance of PCS specimens under both ambient and elevated temperatures. The study recommends the parameters for cohesive surface interaction properties between the insulation material and concrete to enhance the accuracy of numerical simulations.