Effects of grid-type shear connector arrangements used for insulated concrete sandwich wall panels with a low aspect ratio

Insulated concrete sandwich wall panels (ICSWPs), in which low thermal conductivity insulation is inserted between concrete wythes, can minimize the heat loss of building envelopes, and glass fiber-reinforced polymer (GFRP) grids are used to enhance both the structural and thermal performances of ICSWPs. For ICSWPs with low aspect ratios similar to a two-way slab, while bidirectional arrangements of shear grids may be considered based on two-way load transfers, unidirectional arrangements could be economically advantageous due to easier assembly of insulation and grids. This study aims to investigate the effects of grid-type shear connector arrangements on composite behaviors of ICSWPs. Bending tests were performed on four full-scale specimens to examine crack loads, stiffnesses, and strengths. Test variables consisted of GFRP grid arrangements and quantity of GFRP grids. The GFRP grid arrangements were divided into the unidirectional arrangement-installation of GFRP grids in only shorter span direction-and the bidirectional arrangement-installation of GFRP grids in both shorter and longer span directions. Major and minor axes were investigated by measuring radius of curvatures and slips in two perpendicular axes. The results revealed one-way slab behavior, with about nine times greater radius of curvature in minor axis than in major axis. As the result of quantifying degree of composite actions, the bidirectional arrangement in ICSWP demonstrated enhanced serviceability regarding crack loads and stiffness but had lower strength performance. Since the unidirectional arrangement in ICSWP exhibited acceptable composite actions conforming to the design criteria even with 11.4% less quantity of GFRP grid than the bidirectional arrangement, unidirectional installations of GFRP grid could be efficient design options of ICSWPs with low aspect ratios.