Low‐Velocity Impact and Compression After Impact Behaviors of BFRP I‐Beams: Effects of Impact Location and Repetition

ABSTRACT Composite I‐beams are widely used in civil and marine engineering and transportation sectors, but their damage mechanisms under low‐velocity impact (LVI) remain insufficiently understood. This paper experimentally investigates the LVI and compression‐after‐impact (CAI) behaviors of BFRP I‐beams, focusing on the effects of impact energy, flange impact location, and repeated impacts on the mechanical response and damage mechanism. The BFRP I‐beams were fabricated using the vacuum‐assisted resin infusion (VARI) process with the aid of a cubic mold. CAI strain evolution was performed via digital image correlation (DIC) techniques. The results show that LVI response of BFRP I‐beams exhibits a characteristic double‐peak force. The impact failure modes include denting and interlaminar delamination in the top flange, as well as splitting and debonding at the flange‐web junction, together with web fiber breakage. Mid‐span impacts result in pronounced global bending, severe damage, and increased peak forces. Repeated impacts lead to damage accumulation and a significant degradation of residual performance. In CAI tests, end impacts trigger end buckling, whereas mid‐span impacts induce through‐thickness cracking in the impact region. Energy absorption decreases by approximately 26% after the first impact, and subsequent impacts shift the failure mode from abrupt fracture to global buckling.