Mechanical performance of reinforced concrete sandwich shells with different boundary conditions

Concrete sandwich panels have been extensively used due to their cost-effective and multi-functional capacities. Building on this concept, concrete sandwich shells were developed, which extends their applications to curved structures. The objective of this paper is to study the mechanical performance of prototype concrete sandwich shells. First, full-size concrete sandwich and solid shells with the same dimensions were manufactured and tested using four-point bending test, considering both simple support and axially restrained support boundary conditions. Next, Finite Element (FE) models are constructed, and good correlations can be observed between experimental and FE results. It can be concluded that, before concrete cracks, the degree of composite action between the sandwich shell and the solid shell is similar. Under the simply-supported boundary condition, the existence of the connectors in the sandwich shell leads to an increased reinforcement ratio, resulting in a higher ultimate load (936 kN) compared with that of the solid shell (580 kN). Under axially restrained support boundary condition, the ultimate load of the sandwich shell (1847 kN) is lower than that of the solid shell (3505 kN), due to the significant axial force. The solid shell, which has a thicker concrete wythe, exhibits higher bending capacity. Finally, the FE model is used to conduct a parametric study on the sandwich shell. It is found that, as the number of the rows of connectors increases, the ultimate load of the shells increases. The load-bearing capacity of the sandwich shell with the thickness from 130 mm to 140 mm is similar, which tends to be stable when the thickness of the insulation is less than 120 mm. Based on this study, it can be shown that, when properly designed, the sandwich shells have enough capacities to be used as structure members, but with lower weight compared with that of solid shells.