Experimental study on displacement capacity of reinforced concrete walls with varying cross-sectional slenderness

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The utilization of thinner and more slender walls in the design of reinforced concrete shear wall structures has become increasingly popular in Chile and other countries. However, while this approach can lead to increased wall strength if the wall length is increased, it may also result in lateral instability. This study presents experimental results obtained from testing walls with variations in cross-sectional slenderness and their impact on out-of-plane lateral instability, while maintaining wall height, information that in the literature is scarce. Three slender walls were constructed with different cross-sectional dimensions: 160 mm by 900 mm (M1), 100 mm by 900 mm (M2), and 100 mm by 1350 mm (M3). These walls were subjected to a constant axial load and a cyclic lateral load. It was found that the strength of each specimen was consistent with the variation in its cross-sectional dimensions, while maintaining the distribution of steel reinforcement. However, walls with reduced thickness and increased length showed evidence of both local and global lateral instability. Specimen M1 presented concrete crushing, longitudinal bar bucking and fracture, whereas M2 presented a decreased stable confined portion of the wall compared to wall M1, yielding local instability. Wall M3, on the other hand, with a larger wall length, presented larger cracks that favored an unstable out-of-plane behavior of the entire wall section, leading to a sudden strength loss due to its inability to maintain the axial load. As a result, the drift capacity of these walls was found to decrease from 4.2% to 3% with thickness reduction, and to 1.2% with thickness reduction and increased length.