Seismic performance of dual RC frame-shear wall buildings with nonparallel shear walls: insights and recommendations

This study investigates the seismic performance of reinforced concrete (RC) dual frame-shear wall buildings with nonparallel system irregularities under both far-field and near-field ground motions. Utilizing nonlinear time history analysis and Incremental Dynamic Analysis (IDA), seven six-story RC models—comprising one regular and six irregular configurations—are analyzed to evaluate collapse capacities, torsional responses, and story drift demands. The findings challenge the classification criteria in ASCE 7–22, revealing that minor wall inclinations (up to ~ 14°) have a negligible impact on collapse capacity, whereas more pronounced inclinations (~26.5°) significantly increase local seismic demands and compromise structural performance. The results suggest that local wall inclinations have a more significant impact on collapse resistance than overall torsional irregularity, highlighting the need for refined regularity classifications that consider localized effects rather than relying solely on global torsional behavior. Although enhanced design strategies improved collapse resistance, they failed to ensure secure performance in highly irregular models, even when fully compliant with seismic code provisions. Near-field ground motions intensified structural vulnerabilities, prompting earlier collapse onset and necessitating stricter criteria for distinguishing between regular and irregular models. These findings underscore the challenges posed by short-duration, high-intensity seismic pulses and the limitations of current design provisions in mitigating their effects. This study emphasizes the need for refined classification criteria and performance-based design improvements to better capture the complex behavior of nonparallel system irregularities, offering critical insights for developing more resilient structural design frameworks.