Hysteretic Shear Model for Reinforced Concrete Members

A hysteretic model is proposed for shear response of reinforced concrete members subjected to shear force and bending moment reversals. The model consists of a primary shear force‐shear displacement curve and unloading and reloading branches under cyclic loading. The primary curve is the envelope curve for the hysteretic relationship, and can be considered the same as the force displacement relationship under monotonic loading up to the onset of strength decay. A primary curve established by any acceptable procedure, with well‐defined cracking and yield points, can be used in constructing the model. The rules proposed for unloading and reloading branches of the model were obtained from a large number of test data. Full‐scale column tests, under inelastic load reversals, were used for this purpose. These rules were developed to predict experimentally observed stiffness degradation and pinching of hysteresis loops. Empirically derived expressions were included to introduce the effects of axial load, deformation level, and the number of deformation cycles. The model was employed to reproduce the results of large scale tests of reinforced concrete elements. The comparisons include columns, beams, and structural walls, tested by different investigators. Individual hysteresis loops of small and large deformation cycles are compared with those produced by the model. The results show a good agreement between the model and the experimental data.