Finite element analysis of foam protected RC members against blast loads

Abstract

In this paper a load cladding structure interaction model based on finite element method is developed to simulate response of foam protected RC members to blast loads. In the load cladding structure interaction model, the foam cladding layer over the member is modelled as inelastic springs with nonlinear stiffness and a series of springs are connected at each node of the member. Consequently, the reflected blast pressure is transmitted to the RC member through these series of the springs. The material nonlinearity: in the nonhinge region is incorporated through the flexural rigidities of the member obtained from a nonlinear moment curvature relationship; and in the hinge region using the nonlinear moment rotation relationships directly as spring elements. The nonlinear dynamic equations are solved using the Newmark beta time integration technique in combination with a Newton Raphson iteration technique for handling the nonlinearity in the system. The reflected pressure at any time instant is used to form the load vector at any instant in the time integration process. The coupled load cladding structure interaction model, was then validated by field blast test data.