This study examined the impact behavior and failure mechanism of corroded reinforced concrete (RC) beams strengthened with fiber reinforced polymers (FRP) grid-ultra-high-performance concrete (UHPC) composites. Finite element (FE) models were developed and thoroughly validated against existing experimental data. Furtherly, the effects of corrosion rate, strengthening scheme, and impact velocity were systematically analyzed. The results indicate that corrosion of longitudinal rebars concentrated flexural damage in the impact region and increased deformation. Both pure UHPC and FRP-UHPC strengthening enhanced flexural resistance and reduced sectional damage factor by up to about 44%. While minimally affecting the first peak impact force, both strengthening significantly increased the second peak. However, the high stiffness of FRP-UHPC layer induced stress concentration at the UHPC-normal concrete (NC) interface, leading to premature debonding. Transverse U-shaped anchors mitigated debonding, though local debonding might persist in unanchored zones. Increasing interfacial bond strength, simulating rebar planting, could effectively prevent interface debonding, but required approximately twice the normal strength. Therefore, a combined strategy employing interfacial rebar planting and transverse U-shaped anchors at a spacing less than 1.0h0 (h0 is the beam effective depth) is recommended to suppress debonding and fully utilize the material potential of FRP and UHPC.
Xiaopu Zhang — School of Civil Engineering, Hunan University of Science and Technology, Xiangtan, 411201, China
Tao Liu — School of Civil Engineering, Hunan University of Science and Technology, Xiangtan, 411201, China; Earthquake Engineering Research and Test Center, Guangzhou University, Guangzhou, 510006, China
Nengcong Wu — School of Civil Engineering, Hunan University of Science and Technology, Xiangtan, 411201, China
Lin Chen — School of Civil Engineering, Hunan University of Science and Technology, Xiangtan, 411201, China
Sanghee Kim — Department of Architectural Engineering, Kyonggi University, Suwon, 16227, Republic of Korea
Zhixiong Zheng — China Construction Fifth Engineering Division Co., Ltd., Changsha, 410004, China
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