Buckling of Steel Reinforcing Bars in Medium-Rise Reinforced Concrete Shear Walls

The experimental results of six medium-rise shear walls, tested as cantilevers under static cyclic loading, are examined to underline the importance of the buckling of the compressive steel reinforcing bars that has been found to be critical for the total behavior of the walls. Nonlinear beam element numerical analysis was conducted, where the effect of buckling of longitudinal reinforcement was taken into account as a diminution in the material stress-strain curve. A model to describe the post-buckling branch of the steel stress-strain curve is proposed for the case of elastic buckling (which is likely to occur in older; existing, nonconforming shear walls) as a supplement to the existing models for inelastic buckling. The numerical results are compared with the experimental ones, showing that considering only buckling in a stress-strain level seems to be a satisfactory approach for accounting for the influence of reinforcing bar buckling to the wall strength and deformation capacity.