Effect of Large Negative Phase of Blast Loading on Structural Response of RC Elements

Abstract

Abstract. Structural response of reinforced concrete (RC) elements for analysis and design are often obtained using the positive phase of the blast pressure curve disregarding the negative phase assuming insignificant contribution from the negative phase of the loading. Although, some insight on the effect of negative phase of blast pressure based on elastic single-degree-offreedom (SDOF) analysis was presented before, the influence of negative phase on different types of resistance functions of SDOF models and on realistic finite element analysis has not been explored. In this study, the effects of inclusion of pulse negative phase on structural response of RC elements from SDOF analysis and from more detailed finite element analysis have been investigated. Investigation of SDOF part has been conducted using MATLAB code that utilizes non-linear resistance functions of SDOF model. Detailed numerical investigation using finite element code DIANA was conducted on the significance of the negative phase on structural response. In the FE model, different support stiffness was used to explore the effect of support stiffness on the structural response due to blast negative phase. Results from SDOF and FE analyses present specific situations where the effect of large negative phase was found to be significant on the structural response of RC elements.

Influence of EBR on the structural resistance of RC slabs under quasi-static and blast loading: Experimental testing and numerical analysis

“…Albeit, it is noteworthy to mention that in a true design case, where a free-field explosion scenario is typically considered, the negative phase might be considerable and worth including in the analysis. In such a scenario, and according to Syed et al [17], while no further damage in the non-loaded face would be expected, an increased damage would be observed in the loaded surface, as a result of an increased rebound deflection. This is especially true when peak negative pressure is considerable compared to peak positive pressure.…”