Behavior of FRP seawater sea-sand ECC composite slabs under different loading conditions

Abstract

The combination of seawater sea-sand engineered cementitious composites (SS-ECCs) and the fiber-reinforced polymer (FRP) is a new type of structural form that overcomes the defects of reinforced concrete (RC) structures, such as the difficulty in obtaining raw materials and susceptibility to corrosion constructions of offshore islands and reefs. This study proposed a new type of FRP SS-ECC composite slab that uses FRP profiles as the bottom mold and bottom tension component and replaces traditional concrete with the SS-ECC. The slabs were tested under different loading conditions, including four-point bending, center single-line loading, and single-point loading at different locations. The load-deflection response, damage pattern, strain characteristics, and energy absorption were analyzed. The load-bearing capacity of the composite slab was the highest under the four-point bending condition. Single-point eccentric loading was a more unfavorable working condition for the composite slab, wherein the slab consumed less energy and failed earlier. The varying degrees of shear tearing of the side plate of the FRP profile were the main causes of specimen failure. The longitudinal strain changes in the FRP profile at the bottom were uniform, whereas the force conditions, strain variations, and distributions of T-ribs and GFRP bars varied considerably depending on the loading conditions. Composite slabs did not have the same ductility as RC slabs, and their energy absorption was lower than that of RC slabs. However, the bearing capacity of composite slabs was significantly greater than that of RC slabs, and composite slabs exhibited a large residual bearing capacity after peak failure.