Shear behavior of reinforced concrete walls under variable axial tension-compression and cyclic lateral loads

Under a strong earthquake, the axial force of shear walls in tall buildings may vary from compression to tension, but few studies have been conducted on this. Three low-aspect-ratio reinforced concrete (RC) wall specimens subjected to coupled variable axial tension-compression and lateral load were tested in this study, to investigate the effect of the fluctuating range of axial force and loading histories on the shear behavior of RC walls. The test results indicated that shear-compression failure occurred under the compressive-shear loading for all test wall specimens, and no obvious post-peak strength degradation in tension-shear loading. The hysteretic curves of test wall specimens were strongly affected by the loading histories; the shear strength and deformation capacity were mainly affected by the fluctuation of axial forces, especially for tension-shear strength. The equation of ACI 318-19 and JGJ 3-2010 conservatively predicted the shear strength of RC walls under the variable axial force, while the equation of ASCE/SEI 43-05 accurately predicted the shear strength with the mean values of the V^Test/V^ASCE of 0.97 and 0.94 for compression-shear and tension-shear strength, respectively. Comparison with an RC wall under constant axial tension revealed that the failure modes of RC walls were strongly dependent on the initial cracking patterns. Finally, a finite element (FE) model was developed, and parametric analyses were carried out to further estimate the effect of variable axial force on the cyclic shear behavior of RC walls.