SDOF Isn't Dead—The Role of Single Degree of Freedom Analysis in the Design of Columns against Close-In Blast

Abstract

The use of Single Degree of Freedom (SDOF) analysis for the design of columns under non-uniform blast load is investigated and, through comparison with dynamic finite element analysis, the limits of validation are identified for calculation of lateral displacements and dynamic reaction forces. First-principles derivation of the displaced shape of the element under a generalised load distribution, including account for shear deformation, permits the lateral displacement and flexural state of stress to be calculated with confidence, improving on the limits of validation of standard solutions for an equivalent uniform load and assume the location of plastic hinge formation. The dynamic reaction forces are considered and the extent to which higher modes affect the results of the analysis determined. Limits of validation of SDOF analysis for the calculation of reaction forces within reasonable accuracy are determined.