격자형 CFRP 보강재를 활용한 인장강화효과의 실험 및 해석적 연구

초록

This study aims to elucidate the tension-stiffening effect of concrete members reinforced with grid-type CFRP under direct tensile loading. For this purpose, direct tensile tests were performed on specimens with two parameters: concrete compressive strength (30 MPa, 60 MPa) and transverse grid spacing (0 mm, 100 mm). Furthermore, a three-dimensional finite element analysis model featuring a cohesive-zone formulation was developed using the ABAQUS/Explicit solver to simulate the bond response at the interface between the CFRP grid and concrete. All specimens exhibited a typical three-stage response: an elastic phase, a crack-development phase, and a residual-tension phase. The transverse grid ribs reduced the average crack spacing and produced a more dispersed crack pattern, while higher concrete strength delayed the onset of cracking. The tension-stiffening model in Eurocode 2 reproduced the overall stress-strain trend but consistently overestimated the initial cracking strain. In contrast, the finite element analysis model accurately simulated crack initiation, propagation, and internal stress redistribution, predicting crack patterns and average crack spacing in close agreement with the experimental results. These findings quantify the crack-control performance and validate the design applicability of grid-type CFRP reinforcement and provide a basis for durability-focused design guidelines for concrete structures.

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