Cyclic load behavior of low-slenderness reinforced concrete walls: Design basis and test results

The present study addresses the problem of cyclic shear in squat reinforced concrete walls and attempts to assess the validity of current design provisions, both in Europe (Eurocode 8) and in the U.S. (ACI 318). The paper describes a comprehensive experimental program involving 11 wall specimens, six with shear span ratios of 1.5 and five with 1.0, detailed to the provisions of EC8; problems in applying these provisions are pointed out and comparisons with the corresponding ACI 318 provisions are also made. The wall specimens are reinforced against shear, either conventionally (orthogonal grids of web reinforcement), or with cross-inclined bars; the effects of web and edge reinforcement ratio, of axial load level, and of the quality of construction joints are also investigated. The reported test results clearly show that properly designed and reinforced walls can reach their flexural capacities, even when their aspect ratio is as low as 1.0, that sliding shear in this category of walls is not a major problem, and that cross-inclined (bidiagonal) web reinforcement can effectively and economically control sliding and the subsequent pinching of the hysteresis loops, particularly when these bars intersect close to the critical section.