EVALUATING STRUCTURAL DYNAMICS BEHAVIOR UNDER BLAST LOADING WITH AND WITHOUT OPENINGS BASED ON UFC 3-340-02

Abstract

This article presents a quantitative investigation into the influence of venting areas on the dynamic Response of Reinforced Concrete (RC) box-type structures subjected to surface blast loading. Blast wave parameters, including reflected pressure Pr and internal pressure resulting from blast wave ingress, are determined based on the empirical design charts provided in the U.S. Department of Defense Unified Facilities Criteria UFC 3-340-02. Numerical simulations were conducted using Nonlinear Time-History Analysis in SAP2000 to compare two distinct scenarios: a fully enclosed structure and a structure configured with functional openings (doors and windows). The results show that the presence of venting areas significantly alleviates the pressure acting on the front face and the roof. Simulation results indicate that the peak displacement of the roof and side walls decreased by 45% and 22%, respectively, compared to the enclosed configuration. However, the openings allow the blast wave to penetrate the structure, leading to internal reflections that cause a sudden increase in load on the interior surfaces. Specifically, the displacement of the rear wall in the opened configuration increased by 58% compared to the enclosed case. The research confirms that while openings significantly alter pressure distribution and alleviate direct blast impacts, they induce intensified internal reflected pressures. Therefore, localized reinforcement of elements facing the blast direction is required, providing a groundwork for designing perforated external shells that safeguard a fortified internal core.