Failure time of reinforced concrete column under blast load

Abstract

To explore the damage and the failure time of the reinforced concrete column in an adjacent physical field of explosion, a comprehensive finite element model of TNT-air-column in the software LS-DYNA is set up in consideration of the advanced numerical simulation technologies (i.e., element birth and death technology, large deformation technology, contact technology, etc) and the strain rate effects of the concrete and steel materials. First of all, an explosion test is conducted on two scale models of the reinforced concrete column, and the finite element model is validated by comparing the numerical simulation results with the experimental data. The failure process, failure mode, and failure criterion of the reinforced concrete column under blast load are further investigated. Thereafter, a series of parameter studies are conducted to investigate the damage and the failure time of the reinforced concrete column. Finally, a new method is proposed to estimate the failure time of the reinforced concrete column and the corresponding basic steps are given in this study. Through the researches and analyses of the typical cases, the results show that the failure modes change from punching failure to compression-flexure failure via compression-shear failure with the increase in the scaled distance. The medium damage and the high damage occur mostly on the reinforced concrete column in an adjacent physical field of explosion. The damage index of the reinforced concrete column varies significantly with the compressive strength of concrete, column height, column depth, longitudinal reinforcement ratio, transverse reinforcement ratio, and axial compression ratio, especially the column depth and the axial compression ratio; however it has little relation with the column width. The failure time of the reinforced concrete column is up to tens of milliseconds or even more than one hundred milliseconds. The calculation formulas used in the proposed method are based on previous research and simulation results. The proposed method is rigorous and thorough and the predicted results are highly accurate and effective. Besides, this method can provide a good prediction of the failure time of the reinforced concrete columns with different axial compression ratios.