Dynamic amplification of isolated shear walls: Insights from layered shell modeling

This study investigates the dynamic shear amplification factors in reinforced concrete wall systems subjected to seismic ground motions. After validating a modeling strategy for shear walls using layered shell elements, a comprehensive parametric analysis was performed using approximately 1460 numerical models, of which 343 satisfied convergence and capacity criteria and were retained for evaluation. Analysis of walls ranging from 35 to 105 m in height with web transverse reinforcement from 0.25% to 1.40% revealed dynamic shear amplification factors between 1.0 and 2.75. Maximum amplification occurred in taller walls under low axial load ratio (0.10 (Formula presented) ), while high axial load ratios (0.30 (Formula presented) ) reduced peak amplification to approximately 1.5. Statistical analysis identified the normalized position of the resultant lateral force as the most accurate predictor of dynamic amplification. A regression model based on the normalized force resultant position was developed and validated through normality tests of residuals, demonstrating robust agreement with observed data. Mean amplification trends showed reasonable agreement with ACI 318-25 formulations, though substantial scatter indicates that the effective position of the force resultant is essential for accurate prediction beyond the number of stories alone.