Behaviour of Steel and Steel-Concrete Sandwich Panels under Combined Blast and Fragment Loadings

Abstract

This thesis is focused on analysis the behaviours of two forms of protective panels, namely (i) steel built-up panel formed by welding of standard beam sections and plates and (ii) steel-concrete sandwich panel (SCS), subjected to combined blast and fragment loadings (CBFL) experimentally and numerically. Three explosion trials, including a bare charge of 2.7 kg TNT and two cased charges of 15 kg of TNT encased in a mild steel pipes, were performed. After the explosion trials, static bending tests of the damaged panels were carried out to estimate the residual capacity of the damaged panels. In addition, in order to investigate the behaviours of both steel and SCS sandwich panels against fragment loading under laboratory conditions, high velocity impact tests were carried out on both panel which have the similar cross-sectional design and dimensions as blast tests. Numerical models were developed for both steel and SCS sandwich panel to simulate experimental test cases using LS-DYNA finite element software package to further investigate the effects of different loading components (fragment and blast) on structural response. After FE model development, it was validated and compared with the experimental results. It was found that FE model can simulate dynamic responses with reasonable accuracy. The validated FE models were then utilised to conduct comprehensive parametric study to further analyse the panels under different loading and geometric conditions for both steel and SCS sandwich panel. The three types of simplified modelling techniques namely (a) Single degree of freedom (SDOF) model, (b) multiple degree of freedom (MDOF) model, and (c) simplified finite element model (SFEM) were developed to predict the responses of the steel and SCS sandwich panels under CBFL generated from cylindrical cased charge. It was found that the responses matched with reasonable accuracy when compared with experimental and detailed FE model results considering its simplicity of the modelling as well as significantly reduced analysis time required. After development and validation of simplified models, comparative investigations were carried out to evaluate the performance of the simplified models.