Experimental investigation on the size-dependent CFRP shear contribution in CFRP-strengthened RC shear wall

Most of the current methods for estimating the shear contribution of CFRP are based on laboratory testing of small-sized specimens. The applicability of the current codes on large-sized FRP-strengthened shear walls remains debatable. The present study addresses the problem by investigating the combined effects of structural sizes and CFRP ratios on the shear contribution of CFRP. Through experiments, a series of geometrically similar CFRP-strengthened RC shear walls were designed and subjected to a cyclic horizontal loading. From the experiments, the following results can be obtained. The application of the externally bonded CFRP strips alters the failure mode and enhances remarkably the seismic resistance by suppressing crack propagation and increasing the energy dissipation. The increasing specimen size reduces the enhancement effects of CFRP on the nominal shear strength, ductility, and energy dissipation. These findings indicate that without considering the size effect, the effective strain that reflects the shear contribution of CFRP strips are greatly overestimated by the current codes. Therefore, the present study proposed and validated an effective strain factor capturing the combined effects of the structural size and the CFRP ratio on the shear contribution of CFRP strips, serving in assessing the shear strengthening effect of CFRP on shear walls.