2DOF BLAST ANALYSIS OF BUILDINGS

摘要

Blast loading on buildings may originate from various sources and may be redefined during the lifetime of a building. The blast response of buildings is roughly governed by the response of the fa?ade and the main load bearing structure. While a full FEM analysis in the time domain can provide reliable and accurate results for the building response in detail, a quick assessment based on lumped masses is preferred in many cases in practice, either related to early design stages, decision making or to validation of sophisticated models. In such classical single or multi degree-offreedom approaches the fa?ade and main load bearing structure can be clearly distinguished. In practice both components are usually dealt with individually, conveniently ignoring the effect of the response of the former on the blast load on the latter component. Early graphical tools for the incorporation of non-linear effects have been widely used. Here the results of time-domain analyses of an elasto-plastic 2-degree-of-freedom system in terms of ductility demand are shown and compared to those of corresponding single-degree-of-freedom systems. Explicit results for the interaction of fa?ade members and main load bearing members are obtained and shown for various configurations. It is concluded that representation of structural systems by individual single-degree-of-freedom systems in blast analysis is generally conservative for fa?ade members, but can be unconservative for the main load bearing structure. In practical cases this underestimation is not likely to exceed 10%.