PSI - Issue 78

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

809

Fig. 1. Geometry and reinforcement of RC shear wall specimen

2.2. Material properties Normal-weight concrete with a target 28-day compressive strength of 20 MPa and 10 mm maximum aggregate was used. Cylinder tests (150 × 300 mm) were conducted at 7-day intervals to 28 days and at test completion. Longitudinal reinforcement bars ( ϕ 8, ϕ 10 and ϕ 12mm) were A630-420H steel ( = 420 ), and transverse reinforcement ( 5mm) AT560-500H steel ( = 500 ). Although AT560-500H steel bars are not as ductile as the A630-420H steel bars. the former meets Chilean code requirements for shear reinforcement under capacity-design principles (INN, 2009). 2.3. Test setup and instrumentation The walls were tested in an upright position. The wall specimens were placed within a steel loading frame, where the base was fixed and the top of the wall was free to translate and rotate. Cyclic lateral loading was applied through a horizontal 800 kN actuator, pinned at both ends and connected to the top RC beam by means of four steel bars bolted against 400 × 310 × 40 mm steel plates on each side of the wall. At the left end, the horizontal actuator was bolted to the steel reaction frame. The opposite end was supported from the steel reaction frame using two pulleys to eliminate any vertical reaction on the wall induced by the actuator’s weight . Lateral loading was applied under displacement control. The applied lateral force was resisted by a steel reaction frame anchored to the laboratory strong floor. Load cells were used to monitor the applied load throughout testing. Due to laboratory constraints at the time of testing, no axial load was applied to the specimens. Currently, an axial load system is being developed for future tests. The footing was anchored to the laboratory floor using post-tensioned rods. The walls were instrumented with one load cell, 14 displacement transducers (LVDTs), and 16 strain gauges affixed to the reinforcement bars. The load cell was connected to the horizontal actuator to measure the applied lateral load. Strain gauges were installed to capture strain at specific points on the specimens. A total of 16 strain gauges were mounted on the reinforcement bars, including one on a transverse bar. All strain gauges were positioned at or below the plastic hinge region, which extended slightly less than 160 mm from the base. Installation of the strain gauges was completed prior to concrete casting. LVDTs were employed to measure displacements at designated points on the specimens. Failure was defined as a 20% reduction in the peak lateral load for each specimen. The yield displacement ( Δ y ) was theoretically determined through moment-curvature analysis. The initial yield displacement was estimated from the moment-curvature curves and subsequently updated during testing.