Path-Dependent Stress-Strain Model for FRP-Confined Recycled Brick Aggregate Concrete

Fiber-reinforced polymer (FRP) confinement has shown promise as an alternative method aimed at enabling the structural use of recycled brick aggregate concrete (RBAC) in columns. To facilitate practical applications, an existing stress-strain model for FRP-confined normal concrete is modified in this paper to extend its applicability to FRP-confined RBAC. The modification was based on a rigorous approach involving a direct examination of the path-independent assumption, which was made possible by conducting companion tests on actively confined and FRP-confined RBAC. Comparisons of the stress-strain and dilation responses obtained from the two confinement schemes showed that the axial strain of RBAC can be considered path-independent while the axial stress of RBAC tends to be path-dependent. The underlying cause is probably that the weak resistance of recycled brick aggregate (RBA) makes itself a medium for crack propagation. The effect of path dependence is accounted for in the modified model by purposefully weakening the stress-strain response of actively confined RBAC to correct the overestimate found in the axial stresses of FRP-confined RBAC, which originates from adopting the path-independent assumption.

Automated summary

In this study, the stress-strain model for FRP-confined normal concrete is modified to extend its applicability to FRP-confined RBAC. Comparison of experimental results shows that the axial strain of RBAC can be considered path-independent while the axial stress tends to be path-dependent, likely due to the weak resistance of recycled brick aggregate.