Seismic Performance Assessment of RC Wall Buildings with Low Boundary Confinement using a Nonlinear Beam-Based Model

The performance and safety of modern reinforced concrete (RC) wall buildings with limited boundary confinement remains uncertain in countries with evolving design practices and moderate-to-high seismicity. This paper presents a numerical assessment of their seismic response through nonlinear analyses conducted on 20 code-conforming prototype buildings, developed after examining typical design and detailing characteristics of RC wall buildings constructed in Peru between 2010 and 2023. The analyses employed an efficient beam-based modelling approach for walls that accounts for axial–shear–flexure interaction, previously validated with experimental data. The nonlinear static analyses show ultimate roof drift ratios with an average of 1.35% (ranging from 0.85% to 2.53%) and overstrength ratios with an average of 2.43 (ranging from 1.78 to 3.54), indicating moderate deformation capacity with significant variability across building heights, with failure primarily governed by concrete crushing at wall boundaries under flexural deformations. Their limited displacement capacity is attributed to high axial load ratios, slender wall geometries, low aspect ratios, reduced confinement zones, and low transverse reinforcement ratios. For the design basis earthquake (DBE), displacements obtained from nonlinear dynamic analyses exceeded code expectations by an average factor of 1.6, with displacement demand/capacity ratios ranging from 0.25 to 0.83. Under the maximum considered earthquake (MCE), an average displacement demand/capacity ratio of 0.90 was reached, and multiple buildings experienced global failure. These results suggest that code-based designs may underestimate seismic demands, leading to insufficient seismic joints, greater damage to structural and non-structural elements, and increased collapse risk. The findings provide insight into the vulnerability of RC wall buildings with low boundary confinement in Peru and across other Latin American countries with similar design practices and seismic hazard.