Experimental Investigation of Large-Scale Cladding Sandwich Panels under Out-of-Plane Transverse Loading for Building Applications

This paper investigates large-scale sandwich panels ($9,145\times 2,440\times 78\mathrm{mm}$) subjected to out-of-plane loading. The panels comprise glass-fiber-reinforced polymer (GFRP) skins connected by orthogonal GFRP ribs and a polyurethane foam core. The lightweight insulated panel is supported at three levels along its 9,145-mm height and is proposed for cladding of buildings, where the main loading is caused by wind. A full-scale panel was tested under uniform air pressure by using a specially designed setup equipped with pressure load actuators. The panel failed at 7.5 kPa, 2.6 times the factored design pressure for the windiest region in Canada. Failure occurred by outward wrinkling and crushing of the GFRP compression skin near the middle supports. The deflection under the maximum design service wind pressure did not exceed $\mathrm{span}/360$. Another test was carried out on a different specimen by using conventional mechanical loading. It confirmed the ultimate strength of the panel and also revealed a successive failure response, associated with residual capacity beyond first failure. After skin wrinkling in the negative moment region, the load remained stable, within a 3% variation, until shear failure of the core followed near the middle supports. Because the system is statically indeterminate, it did not suffer global collapse, and the load dropped only 24%. By further loading, the strength increased up to 85% of the first peak when failure occurred by outward wrinkling and crushing of the compression skin in the positive moment region.