Minimum available deformation capacity of reinforced concrete beams

In an effort to provide the structural design profession with an indication of the deformation capacity of reinforced concrete beams subjected to cyclic loading, results of 69 isolated reinforced concrete beam tests were assembled and interpreted. The influence of several parameters, including longitudinal reinforcement ratio, web reinforcement ratio, shear stress, shear span-to-depth ratio, axial load, floor slabs, loading rate, and loading history, on deformation capacity were investigated. It was found that ductility factors in the range of two to nine reasonably may be expected from reinforced concrete beams. Of the parameters investigated, shear was identified as the single most important factor affecting deformation capacity. It was further determined that the effects of shear can be controlled most directly by limiting the demand placed on web reinforcement. To ensure that beams exhibit ductility factors of at least five, it is recommended that the maximum shear force demand on web reinforcement be limited to sixty percent of its nominal capacity.