PSI - Issue 78

Alvaro Lopez et al. / Procedia Structural Integrity 78 (2026) 807–814

808

1. Introduction The destructive potential of subduction-zone earthquakes extends beyond peak ground accelerations to the cumulative damage induced by prolonged shaking. In Chile — where RC shear walls form the primary lateral‐force resisting system for mid- and high-rise buildings — post-2010 Maule investigations revealed concrete crushing, reinforcement buckling, and longitudinal bar fractures attributed to low- cycle fatigue under long‐duration motions (Bazaez & Dusicka, 2016; Rojas et al., 2011). Although these walls met code requirements, their performance exposed vulnerabilities in existing design provisions, which emphasize spectral demands but omit damage accumulation effects. Despite extensive research on duration effects in frames and bridge piers (Chandramohan et al., 2013; Foschaar et al., 2012; Kashani et al., 2017), controlled experimental studies on RC shear walls remain scarce. Addressing this gap, the present work subjects three half-scale, flexure-dominated RC shear walls (700 × 100 × 1600 mm) to displacement protocols informed by nonlinear time-history analyses: a long-duration subduction record, a spectrally equivalent short-duration record, and a standard symmetric cyclic sequence. By comparing crack patterns, hysteretic response, and displacement capacities, this study clarifies how ground motion duration governs failure mechanisms and residual capacity in RC shear walls. The findings aim to enhance the seismic design and assessment of RC wall systems in regions prone to long-duration seismic events. 2. General description of experimental program The experimental program comprised three half-scale, flexure-dominated RC shear-wall specimens designed to replicate critical wall typologies observed in Chilean buildings damaged by the 2010 Maule earthquake (Westenenk et al., 2013). All specimens share identical materials, cross-sectional dimensions, and reinforcement ratios; the only variable is the cyclic loading protocol. This configuration isolates the effect of ground-motion duration on damage accumulation and seismic performance. For the wall specimen design, a ½ scale was adopted for the prototype due to laboratory constraints. The wall cross section measures 700 mm in width, 100 mm in thickness, and the total wall height is 1600 mm (see Fig. 1). Consequently, the height-to-length ratio (ℎ/ ) of the prototype is 2.3. To facilitate connection to the loading system, the wall was constructed with RC beams at both the base and the top. The lateral load was applied at the mid-height of the top beam, corresponding to 1750 mm from the base, resulting in a moment-to-shear span ratio ( / ) of 2.5. Although this value slightly exceeds the average ratio of 2.02 observed in surveyed walls (Westenenk et al., 2013), it remains within the practical range and ensures a flexural failure mode. The vertical boundary reinforcement consists of four 10 mm diameter bars ( = 0.45%) , while the distributed vertical reinforcement comprises 8 mm diameter bars spaced at 140 mm in two layers ( =0.72%) . The horizontal distributed reinforcement uses 5 mm diameter bars spaced at 90 mm ( = 0.44%). A different steel type was selected for the horizontal reinforcement to accommodate the available bar diameters, which allowed achieving a spacing-to diameter ( / ) ratio of 9.0, where s is the spacing of horizontal bars and is the diameter of the vertical bars. This ratio falls within the 8 – 11 range typically observed in damaged RC walls (Wallace et al., 2012). The / ratio is significant, as vertical bar buckling has been identified as a critical issue; in practice, horizontal reinforcement bent at the wall edges helps restrain this buckling. The reinforcement ratios in the wall specimens align closely with the average ratios identified in surveys of damaged buildings, except for the distributed vertical reinforcement ratio ( =0.72%) , which is lower than the survey average of 1.08%. The horizontal reinforcement detailing follows common Chilean construction practice, employing hoops with 90-degree hooks placed outside the vertical bars; these are not anchored within the concrete core and become ineffective following the spalling of the concrete cover (Massone et al., 2012). The reinforcement details for the base and top beams, not shown in Fig. 1, consist of 12 mm diameter longitudinal bars, supplemented by intermediate 10 mm longitudinal bars and 8 mm diameter stirrups spaced at 100 mm. 2.1. Specimen geometry and reinforcement