RR435 - Improved simplified response methods to blast loading
This report describes the second-stage extension of a sophisticated SDOF model for steel members subject to explosion loading , previously developed under commission from the Steel Construction Institute.
The previous model  accounted for i) generalised support conditions for bending and axial actions, and ii) the catenary effect in axially-restrained members, under uniformly distributed (UDL), blast loading. However, this model did not incorporate material rate sensitivity, which has considerable influence on the blast response of steel members. This work extends the previous model  to deal with the strain-rate effect, and to provide more rational ductility measures than possible with rate-insensitive modelling.
The report proceeds by providing an overview of the problem characteristics as well as the formulation method used in developing the new SDOF model, where consideration is given to material rate sensitivity in accordance with the Cowper-Symonds model . The details of the overall model are then provided, mainly in the form of parametric tables, covering both the bending and catenary stages of the plastic ratesensitive member response. Finally, several verification and application examples are provided, with particular emphasis given to the new developments, where comparisons are made against the nonlinear finite element analysis program ADAPTIC . These examples demonstrate the calculation process involved in applying the new SDOF model, and illustrate the very good accuracy which the new model achieves.
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