Generation of pressure–impulse diagrams for failure modes of RC columns subjected to blast loads

The Pressure–Impulse (P-I) diagram is generally accepted as a useful tool that permits easy assessment of structural responses to a specified load. To predict the failure characteristics of typical reinforced concrete (RC) columns subjected to blast loads, P-I diagrams considering different failure modes were generated with a high efficient procedure by employing an improved nonlinear analytical approach. In the nonlinear analytical approach that was improved from the Timoshenko beam theory, failure criteria to determine typical bending failure, diagonal failure and direct shear failure modes of RC columns were defined, respectively. The proposed efficient procedure was compiled to generate the P-I diagram by successively circular the improved nonlinear approach which was validated by conducting field blast tests. Parametric studies were carried out to investigate the effects on the failure characteristics of RC columns in the generated P-I diagram, including blast loads distribution, axial compression ratio, slenderness ratio, cross-section bend capacity and shear capacity. The analytical results demonstrate that the diagonal shear failure is most likely to occur on the typical RC columns subjected to blast loads. The bending failure basically occurred when the axial compression ratio and slenderness ratio of RC columns are large to a certain extent.