Shear Span–Depth Ratio Effect on Behavior of RC Beam Shear Strengthened with Full-Wrapping FRP Strip

Abstract

Shear span-to-effective depth ratio (av/d) is known to affect the shear behavior of RC members. However, this effect has not been appropriately addressed in existing design guidelines for the fiber-reinforced polymer (FRP) strengthening of RC structures. This paper focuses on the effect of av/d on the behaviors of RC beams shear strengthened with full-wrapping FRP strips. A total of six strengthened beams and six normal beams are tested, with av/d ratios ranging from 1.0 to 3.5. The experimental results indicate that the FRP shear contribution increases initially with the av/d ratio, but decreases when the ratio is beyond 2.5. The FRP strain along the critical shear crack distributes in different manners for different av/d ratios. The authors’ experimental results and the test results from the literature are compared with predictions from available design guidelines. Although some recent design guidelines always provide a safe value, it can be overconservative. Conversely, other recent design guidelines may overestimate the shear-strengthening effectiveness at low span/depth ratios so they have to be used with caution.