Effect of Axial Load on Shear Behavior of Short RC Columns under Cyclic Lateral Deformations.
Ramirez, H.; Jirsa, J. O.
National Science Foundation, Washington, DC. Engineering and Applied Science., June 1980, 175 p.
The influence of axial loads on the behavior of reinforced concrete short columns under cyclic bidirectional deformations was studied. The experimental program consisted of ten tests of short column specimens subjected to predetermined load sequences. All specimens had the same geometry and reinforcement. Their shape was selected to simulate a short column framing into a stiff floor system. Lateral loading was controlled by monitoring deformations. Two basic histories were selected--one with displacement variation in only one direction and the other with displacements applied alternately in orthogonal directions. The main effect of axial compression was an increase in shear strength and acceleration of shear deterioration at higher levels of deformation when compared with that of a specimen without axial loads. In tests with constant tension, shear capacity and stiffness were reduced, but shear deterioration decreased when compared with tests using constant compression or no axial load. To develop a design approach for columns failing in shear, a parameter was defined to establish shear behavior. Guidelines were set for satisfactory performance in terms of energy dissipation. The procedure appeared to reflect adequately the influence of main variables as indicated by the limited available test data.