Protective Facility ISSN:3058-7816(Print) 3058-8618(Online) 방호시설

In blast-resistant design, rational estimation of the natural period of walls is essential for evaluating structural response under blast loading. However, the estimated natural period may vary depending on wall thickness, boundary conditions, modeling range, and assumed deformation behavior, which can lead to differences in design evaluation. This study investigated the effects of these variables on the natural period of blast-resistant walls by comparing analysis-based methods with equivalent single-degree-of-freedom (SDOF) approximation methods. For the analysis-based evaluation, finite element eigenvalue analyses were performed using both isolated wall models and whole-structure models. For the SDOF-based evaluation, natural periods obtained from one-way and two-way behavior assumptions were compared. The results showed that the natural period generally decreased as wall thickness increased, although the rate of change and deviation differed depending on the modeling range and boundary conditions. In particular, the isolated wall model showed relatively good agreement with the two-way behavior-based approximation, whereas the whole-structure model exhibited relatively large differences from the one-way behavior-based approximation. These findings indicate that the natural period of blast-resistant walls should not be determined by a single simplified method alone. Instead, one-way and two-way SDOF-based approximations should be used as upper- and lower-bound reference estimates, and their applicability should be comprehensively evaluated together with analysis-based results according to the modeling level and design purpose.