Abstract:
Under strong ground motions, some shear walls in high-rise buildings might be subject to combined axial tension and shear forces. This paper presents a series of quasi-static tests in which six large-scale RC wall specimens with low aspect ratios were subjected to axial tensile forces and cyclic shear loadings. The tensile-shear behavior of low-aspect-ratio RC walls was investigated, including the failure modes, hysteretic responses, strength and stiffness. The test results indicated that the failure mode of the wall specimens varied with axial tensile forces, including shear failure (the tensile stress ratio of vertical rebars
ns=0), shear-sliding failure (
ns=0.23~0.63) and sliding failure (
ns=0.8~1.0). Under the axial tensile loading, the experimental values of the cracking tensile load of the wall specimens were 0.6~0.7 times the theoretical values, while the experimental values of the initial tensile stiffness and post-cracking stiffness were close to the theoretical values. The presence of tensile force significantly affected the lateral strength of the RC walls. The specimens of
ns=0.63 and
ns=1.0 had lower peak lateral loads by 54% and 76% than the counterpart specimen without tensile force, respectively. The presence of tensile force also led to a decrease in the effective lateral stiffness of the wall specimens. The effective lateral stiffness of the specimens of
ns=0.23~0.63 was approximately 0.56 times that of the counterpart specimen not subjected to tensile force, and it was only 1/10 of the theoretical value of the initial stiffness. This study recommends the formulas used to calculate the effective lateral stiffness of low-aspect-ratio RC walls under coupled tensile and shear forces. The predicted values from the formulas show good agreement with the test results of those specimens that failed in a shear-sliding mode. Finally, the design formulas specified in various codes were compared with the test results. The ACI 318-14 (United States) and EuroCode 8 (Europe) formulas underestimate the tensile-shear strength capacity of the low-aspect-ratio RC wall specimens in this experimental program, with the ratio of experimental-to-calculated values equal to 1.90 and 2.41, respectively. The JGJ 3-2010 (China) formulas might overestimate the tensile-shear strength capacity of RC walls.