Structural performance of composite prefabricated concrete sandwich panels with pultruded square GFRP tubular shear connectors under concentric axial compression

This study presents an investigation into the structural performance of a new type of composite prefabricated concrete sandwich panel (PCSP) with pultruded square glass fibre reinforced polymer (GFRP) tubular shear connectors subjected to concentric axial compression. The experimental tests were performed on three specimens to evaluate the influence of the direction of shear connector placement on the load-bearing capacity of the panels. All three tested panels failed due to crushing of concrete in compression, with no signs of separation of concrete wythes, indicating the excellent composite action provided by the shear connectors. In addition, a finite element (FE) model was established and validated against the experimental load-axial deformation responses and failure modes. Furthermore, the validated FE model was employed to carry out a detailed parametric study examining the effects of spacing of shear connectors, cross-sectional area of the longitudinal reinforcement, compressive strength of concrete, insulation thickness, and slenderness ratio. It was revealed that the spacing of shear connectors, longitudinal reinforcements’ area, slenderness ratio, and insulation thickness have negligible effects on the load-bearing capacity of the panels. At the same time, the increase in concrete strength significantly improved the panels' load-bearing capacity. Besides, a modified empirical model from the existing design code of reinforced concrete structures was used to predict the load-bearing capacity of the PCSPs conservatively against the numerical results, with an average ratio of theoretical to FE prediction as 0.91 and a coefficient of variation (CoV) of 0.02. • A new type of load-bearing composite PCSP is investigated under concentric axial compression. • The proposed pultruded square GFRP shear connectors showed excellent performance in joining two concrete wythes of composite PCSPs. • FE parametric studies were conducted to assess the effects of key parameters on the load-bearing capacity of the panels. • Empirical model showed less than 10 % error in predicting the ultimate strength of the panels.