Coupled vs uncoupled analysis of one-way RC-slabs under nearby air explosions

The numerical techniques used for blast analysis of structures are categorized in “coupled” and “uncoupled” analysis methods. In a coupled analysis, the fluid–structure interaction is taken into account. Such analysis, although more accurate, is often complex and time consuming. In an “uncoupled” analysis, the blast loads are estimated by empirical equations and then applied to the structure in a separate analysis. Such an analysis is more cost effective, and of more interest for most practical design applications. The main objective of this study is to assess the efficiency of the empirical graphs prescribed by the UFC Code for uncoupled analysis of structures under the nearby air explosions of scaled distances between 0.4 and 0.7 kg/m1/3. The main characteristic of such explosions is the highly nonuniform distribution of blast-reflected pressure on the surface of structure. A method has been developed by the authors to address this nonuniform distribution in the uncoupled analysis. To examine the accuracy of analysis, the response values and the pattern of damages introduced on several reinforced concrete slabs under blast loads are compared with the results of a corresponding coupled analysis, and experimental observations. The uncoupled analysis described in this paper can be reasonably employed in the blast analysis and design of many structures.