Seismic Performance and Lateral Strength of Squat Reinforced Concrete Walls with Openings Strengthened by Various Reinforcement Strategies

This study introduces novel reinforcement strategies—namely boundary elements (BEs), increased web reinforcement, and bi-directional diagonal bars—to enhance the seismic performance of RC squat walls with window and door openings, commonly found in rear side exterior walls of low-rise row houses in Taiwan. Experimental evaluation using cyclic lateral loading on four full-scale RC walls with openings revealed that BEs behind the openings significantly improved lateral strength and delayed peak lateral force. However, uneven increases in web reinforcement ratios—98% horizontally and 33% vertically—provided minimal benefit due to premature sliding shear failure. In contrast, bi-directional diagonal bars installed in the vertical wall segment between the window and boundary column significantly increased both lateral strength and displacement ductility, while also delaying peak lateral force compared to other specimens. A structural model was developed to estimate the overall lateral strength of these walls, considering vertical wall segments between openings as piers and segments between an opening and a boundary column as walls. Lateral strength for piers was calculated through sectional analysis, while ACI 318-19 equations were applied to wall segments. Effective dimensions for wall segments were proposed based on observed crack patterns under positive and negative loading directions. The model incorporates contributions from concrete, horizontal web reinforcement, and additional lateral strength from diagonal bars. Comparative analysis demonstrates that the proposed model, based on failure modes, conservatively predicts the overall lateral strength of the tested specimens. •Conducted cyclic testing on four full-scale squat reinforced concrete (RC) walls with window and door openings.•Introduced novel reinforcement strategies to enhance the seismic performance of RC squat walls with openings, including boundary elements beside openings, increased wall web reinforcement, and bi-directional diagonal bars in vertical wall segments.•Proposed an analytical model for predicting the lateral strength of walls with openings.