Structural Performance of Precast Concrete Sandwich Panels Made with FRP Vierendeel Truss-Like Connectors

This paper presents an experimental and a numerical investigation of the structural behavior of precast concrete sandwich panels made with Vierendeel truss-like FRP shear connectors. Two series of tests are reported and analyzed. The first includes two concrete sandwich panels and one solid panel of the same dimensions under four-point bending, and the second includes sandwich and solid panels under eccentric axial compression. The degree of composite action and the post-cracking stiffness in these panels are discussed, along with their modes of failure and load carrying capacity. The panels subjected to bending exhibited a ductile response, with a typical flexural failure characterized by yielding of the steel reinforcement under a similar load level as their counterpart solid panel. The sandwich panels exhibited a partial composite action in the elastic range, but their post-cracking stiffness was comparable with that of the solid panel. The axially loaded sandwich panels failed due to buckling characterized by a limit-point mode, and their strength and stiffness were very close to that of a solid concrete panel with the same dimensions. A finite-element (FE) model is also developed, which describes the partial shear interaction through the elasticity of the various structural components. The predictions obtained from the model are compared with the experimental results and reveal good correlation within the elastic range. The FE model is further used to shed more light on the structural response through a parametric study. The study shows that sandwich panels built with such connectors can provide an attractive design solution given that their stiffness at the precracked stage, and their failure loads were comparable with those of solid panels with the same dimensions.