Dynamic Nonlinear Finite Element Analysis of Blast Resistant Concrete Buildings in Petrochemical Facilities

In a petrochemical plant, there are several buildings that require blast-resistant design such as operator service building, control room, electrical and mechanical buildings, warehouse, administration building, medical and fire stations. These buildings normally have multiple openings and un-symmetric layout. The current approach of blast resistant building design is typically based on a highly simplified dynamic model of a Single Degree of Freedom (SDOF) system. This approach may be appropriate for regular building shapes without openings. For a complex structure with openings, the SDOF system may not be applicable due to closely spaced frequencies between connecting components and difficulty in evaluating the equivalent inertia and stiffness. In addition, the explosions in the petrochemical plants are mostly vapor cloud explosions. For proper design of the buildings, the blast pressure loads need to be applied to the front, side, rear and roof surfaces simultaneously for dynamic response evaluation. In SDOF analysis method, it is a tedious process to transfer pressure load from front wall to roof and then to side walls. Consequently, Finite Element Analysis (FEA) approach becomes a preferred or even required method to evaluate the dynamic response of the complex structure. The main purpose of this study is to demonstrate that the dynamic nonlinear FEA of a concrete structure is a practical approach for blast loadings. During the course of this study, comparisons between FEA and SDOF were made; these comparisons are included in this paper. This paper will also present the effects of openings on the dynamic responses.