In the code for design of concrete structures of China, the influences of cross-sectional shape of column were considered in

the calculation formula of punching shear, but relevant experimental studies were very limited and the mechanism was also unclear. In

order to investigate the influences of cross-sectional shape of column and longitudinal reinforcement ratio on the punching shear

behavior of slab-column connection, 10 specimens were tested  under the axial loading. In the experiments, the cross-sectional shape of

column (including circle, hexagon, square, and rectangle) and the longitudinal reinforcement ratio were defined as variables. The load-

deflection curves, the failure mode and the strain distributions in concrete and steel were obtained through the tests. Based on the

specially designed strain measuring rod, the formation and development of internal shear crack can be observed. In combination with the

test results and the existing experimental data, it is found that the adverse effect of the cross-sectional shape of column on the

punching shear capacity was basically attributed to the stress concentration due to the increase of the ratio um/h0; there are some

unreasonable considerations for the assumed angle of the punching shear conical surface and the calculation of the slab-column

connection of circular column; on the other hand, the internal shear crack was firstly formed at the upper and middle part nearing the

column top, and the shear fracturing characteristics can be observed in the punching shear failure.