Punching-shear behaviors of RC-column footings with various reinforcement and strengthening details

In this study, various reinforcement and strengthening details for the improvement of the punching-shear behavior of concrete footings were developed. Eight test specimens of reinforced-concrete (RC) footings were constructed and tested to investigate the punching-shear behavior of the concrete footings with the developed details. The test parameters include the additional placement of a longitudinal reinforcement around the column-footing connections, the inclination of the shear reinforcement, an additional cast of high-strength concrete, and an additional concrete cast with amorphous metallic fibers (AMFs). The test specimens were supported on a bed of steel car springs that simulate the elastic behavior of soil. The test results show that the punching strength was significantly enhanced by the additional placement of the longitudinal reinforcement around the column-footing connections and by the addition of the retrofit materials (high-strength concrete and AMF-reinforced concrete). Contrarily, the shear reinforcement that was placed around the connections did not significantly affect the punching-shear strength of the footings. The test results were also compared with strength predictions for which the current design codes and the existing theoretical models were used.