Development of a simplifies numerical method for predicting structural response to blast load

[Truncated abstract] Efficiently and accurately predicting structural dynamic response and damage to external blast loading is a big challenge to both structural engineers and researchers. Theoretical investigation on this problem is complex as it involves non-linear inelastic material properties, effect of time varying strain rates, uncertainties of blast load calculations and the time-dependent structural deformations. Most of the theoretical methods are developed based on simplified models which makes their accuracy and application scope limited. Experimental investigation on this issue can provide valuable data for locating the damage and establishing the damage criteria. The damage curves generated from the extensive experimental study can provide quick assessment of the structural status. However, such blast experiments always involve concern about the safety and affordability. Besides this, because of the large nonlinear deformation, experimental data often cannot be extrapolated. Therefore the correlation of the experimental data with predictive method is difficult since it requires a large number of tests to generate damage curves. Compared with the theoretical and experimental study, numerical simulation does not involve any safety concern and it is proved to be cost-effective. With verified material model and element model, numerical simulation could be powerful supplement for the experiments and provide reliable structural response predictions. However, the numerical simulation of modern structures under impulsive loadings could be time and resource consuming. This is because in order to convert the blast energy into the structure and capture the transient wave propagation as well as the localized damage, refined mesh is always required and this requirement makes the simulation process slow and costly. In the first part of this thesis, a numerical method aimed at reducing the calculation cost and ease the numerical simulation effort is proposed. When compared with the natural vibration period of most structures, the blast loading duration is extremely short and there is no sufficient time for the overall structural response to develop during the loading phase, thus the large global deformation and damage usually occur in the free vibration phase. In the proposed method, the structural response is calculated in two steps. In the first step, the structural velocity and displacement response at the end of the blast loading duration is calculated using the theoretical SODF model, and such responses are used as the initial conditions for the second step free vibration analysis...