This study investigates the seismic performance of reinforced concrete shear walls in nuclear power plants using high-strength reinforcing bar through finite element (FE) modeling and probabilistic fragility analysis. High-strength reinforcing bar is increasingly considered for nuclear structures to mitigate reinforcement congestion and improve constructability while maintaining structural integrity. Using experimental data, FE models were developed and validated to accurately capture shear and flexural failure behaviors. Seismic fragility curves were derived based on probabilistic evaluations under various ground motion intensities. The results indicate that shear walls reinforced with Grade 550 MPa and reduced reinforcement ratios exhibit equivalent seismic performance to identically detailed walls except for reinforcing bar grade (Grade 420 MPa). Additionally, a case study on a nuclear containment structure estimates a potential reduction of up to 325 tons of reinforcing bar. These findings highlight the feasibility of applying high-strength reinforcing bars in nuclear structures while ensuring seismic resilience and optimizing construction efficiency.

In the present study, the seismic shear-friction behavior of squat reinforced concrete walls with a construction joint was investigated. To investigate the effect of flexural moment on the shear-friction behavior, 10 wall specimens—rather than conventional push-off (direct shear) specimens—were tested under cyclic lateral loading. The test parameters were the surface roughness, surface roughening method, reinforcement ratio, reinforcement diameter, section geometry, wall aspect ratio, and reinforcement arrangement. The test results showed that roughened interface increased the shear-friction strength, but the difference between roughening methods was marginal. When large diameter rebars were used, the strength degradation due to the cyclic loading effect was less significant. Further, even when the overall amount of reinforcement was uniform, the shear-friction strength increased as the flexural strength–demand ratio increased due to the low aspect ratio and the use of flange. The test results, along with previous studies on shear-friction walls, were compared with the predictions of current design codes, and the effect of design parameters affecting the shear-friction strength were discussed. A nonlinear macro shear-sliding model for shear walls overestimated postyield strength and initial stiffness and underestimated residual strength.

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