Experimental investigation of the mechanical and thermal behaviors of shear connectors in concrete sandwich panels

Concrete sandwich panels (CSPs) are increasingly utilized in building construction due to their effective thermal insulation. While shear connectors are essential for ensuring structural integrity by transferring loads between concrete layers, they can significantly reduce thermal performance by acting as thermal bridges. Therefore, optimizing the geometry and placement of shear connectors is crucial to achieving structural efficiency with minimal thermal compromise. This study experimentally investigates the mechanical and thermal performance of shear connectors in CSPs by varying three parameters: (a) stress condition (tension or compression); (b) connector diameter (6, 8, and 10 mm); and (c) orientation angle (0°, 25°, and 45°). The influence of connector configuration on load-carrying capacity and shear flow is assessed through double-shear tests. Thermal conductivity measurements are then conducted to quantify the effect of connector quantity on heat transfer. The results indicate that shear connectors subjected to tension perform substantially better than those under compression, with load capacity enhancements of up to 339% observed for the 45° 10 mm tension specimen compared to its 45° 10 mm compression counterpart. Increasing the connector diameter enhances structural strength, while a 45° orientation consistently yields superior performance compared to 25° and 0°. However, the incorporation of steel connectors leads to increased thermal conductivity, necessitating careful optimization to mitigate thermal bridging. Based on these findings, practical recommendations for the detailing of shear connectors in CSPs are proposed to achieve an effective balance between mechanical performance and thermal efficiency.