| The potential risks of bridges subjected to terror blast attack are increasing,but there are few studies on bridges against blast. In this paper, the responses of orthotropic steel decks under terror blast loading were investigated with numerical simulation, and special attention was paid to the blasting impulse loads and the failure mechanisms of orthotropic steel decks. The main contents and innovative works include:(1) Based on the Fluid-Solid coupling arithmetic method of ALE Multi-material formulations, the experiments of air explosion and stiffened metal plates subjected to blast load were simulated with the nonlinear finite element software ANSYS/LS-DYNA, in order to demonstrate the feasibility and rationality of the simulation technology used in this paper. The results from the simulation are in good agreement with those from the experiments. The simulation errors of the peak pressure value of air explosion shock wave, the center-deflection and blasting impulse of stiffened metal plates are less than 10%, 11.6% and 10%, respectively.(2) Localised blast loading of stiffened metal plates was investigated with the Fluid-Solid coupling arithmetic method.The effects of stiffness, stiffener configuration, rupture and tearing on the blast loading of stiffened metal plates were analysed. The results show that the blasting impulse increases with the stiffness expressed by equivalent stiffness, but the effects of stiffener configuration, rupture and tearing on blasting impulse are negligible.(3) Based on the formula from assumption of instantaneous detonation, localized blasting impulse formulas for stiffened metal plates were developed by fitting the results from simulation with MATLAB, and were extended to calculate the terror blast loading of orthotropic steel decks. The simulation results show that the blasting responses of orthotropic steel decks from loading with the presented impulse formulas are in good agreement with those from the Fluid-Solid coupling arithmetic method.(4) The plastic deformation, rupture and tearing of steel box girder's orthotropic decks under terror blasting were investigated by a great deal of simulation loading with the presented impulse formulas. The results show that the orthotropic steel decks take place local plastic deformation, rupture or petalling with the increasing of explosive TNT equivalent, and the total energy disspated by the orthotropic steel decks increases linearly with the explosive TNT equivalent approximately. The main disspation mechanisms are the plastic deformation energy of cover plate and lengthways stiffeners, and the ratios of plastic deformation energy to total energy disspated change with the failure form of the orthotropic steel decks. |
