Improved SDOF and numerical approach to study the dynamic response of reinforced concrete columns subjected to close-in blast loading

Abstract

In this study, the blast performance of steel reinforced concrete (RC) columns was experimentally and analytically investigated. The experiments consisted of 11 one-half-scale columns subjected to different levels of blast loading using TNT explosives. The experimental results show that when the scaled distance is relatively large, less damage occurs to steel RC columns with higher axial loads than to columns with smaller axial loads at the same blast level. As the scaled distance decreases, the axial load increases the level of damage to RC columns. In addition, the equivalent single-degree-of-freedom (SDOF) approach for determining the dynamic response of RC columns against combined axial and blast-induced transverse loads was improved. Nonlinear section and member analyses were incorporated into the suggested SDOF method by considering the effect of axial load and complex features of the material behavior, the high strain-rate effect and the column geometry. The SDOF model was validated by comparing the maximum displacements obtained from the SDOF analysis with experimental data from blast testing of RC columns. Parametric studies were also performed to investigate the effects of axial load, the longitudinal reinforcement ratio, transverse reinforcement ratio, aspect ratio and boundary conditions. In order to consider the local damage effect, the numerical study was undertaken to investigate the effects of transverse reinforcement spacing on the blast resistance of RC columns using LS-DYNA.