Mechanical performance of bolted modular GFRP composite sandwich structures using standard and blind bolts

This paper presents a mechanically bolted modular assembly system of GFRP web–flange sandwich structures used for beam and slab applications. Built-up modular sections consisting of standard GFRP pultruded I or box profiles are incorporated between two GFRP plates to form a sandwich structure, which can then be assembled in the transverse direction to form a one-way spanning slab system. Modular sandwich specimens were prepared via mechanically bolting the component profiles, and were then tested under four-point bending. The load-carrying capacity was evaluated, and the degree of composite action and the detail of the bolted connections, such as the spacing and type of bolts, were investigated. It was found that the composite action offered by the bolted connections decreased with the increase of load, and only partial composite action was achieved at ultimate loads. In addition, the degree of composite action was also dependent upon the bolt spacing. Finally, a finite element modeling approach was established to predict structural stiffness and the degree of composite action of bolted GFRP sandwich specimens. The models showed good comparisons with the experimental results.