Development and seismic evaluation of ECC–CFRP composite concrete shear walls

Conventional reinforced concrete (RC) shear walls are susceptible to pronounced concrete crushing and reinforcement exposure at the wall base under severe earthquakes, precipitating abrupt strength and stiffness degradation. Moreover, such walls sustain substantial residual drifts that are challenging and economically onerous to remedy, constraining post-earthquake reparability and seismic resilience. To address these deficiencies, two novel shear wall configurations integrating engineered cementitious composite (ECC) and carbon fiber-reinforced polymer (CFRP) grids were developed, with ECC localized in either the boundary elements or the plastic hinge region of CFRP grid-reinforced walls. The objective is to harness ECC–CFRP synergy to attenuate damage localization, safeguard internal reinforcement, enhance global seismic response, and suppress residual drifts, thereby improving post-earthquake reparability. Four shear wall specimens were subjected to quasi-static cyclic loading to characterize crack evolution, peak load, deformation capacity, energy dissipation, and the strain response of steel reinforcement. Results indicate that both ECC–CFRP configurations markedly enhance seismic performance and residual-drift control relative to the reference wall, with ECC in the boundary elements providing greater gains in lateral resistance and deformation capacity, whereas ECC in the plastic hinge region is more efficacious in mitigating residual drifts. Beyond the experimental evaluation, the specimen responses are further scrutinized to elucidate the energy dissipation and residual-drift/self-centering mechanisms. Capitalizing on these mechanistic insights, a performance-oriented equivalent yielding-state methodology is devised using macroscopic response indices, which more objectively characterizes the enhanced ductility of ECC–CFRP walls while furnishing ductility estimates for conventional RC walls that remain commensurate with classical assessment procedures.