Design of a membrane structure subjected to blast load

Abstract

The dynamic analysis of a tent structure subjected to an external blast load is presented. The case studied refers to temporary structures employed in petrochemical facilities that need to resist to vapor cloud explosions that can happen in the vicinity of the tent. The structure can undergo severe permanent deformations but must not collapse and the maximum displacements have to be limited in order not to harm the occupants. The blast load hits the tent and is transmitted to the supporting structure. Since the membrane has a much smaller period of vibration with respect to the metallic skeleton, an interaction takes place, that substantially modifies the amount of load carried by the supporting structure, that depends also on the details of the design. In the paper a simplified non linear dynamic analysis of the tent structure is performed according to the procedure proposed by API 756. A comparison will be presented between the response of the structure disregarding the dynamic behaviour of the external membrane, and the response calculated considering the interaction between the membrane and the metallic frame. It will be shown that although globally the response of the considered tent is similar in both cases, substantial differences can be found in the estimate of the local deformation.