Assessment of prestressed reinforced concrete box girder bridges under blast loads
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[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT AUTHOR'S REQUEST.] Significant research has been performed on the response and retrofit of buildings under blast loads. Limited research exists on the response prediction and protection of bridges under near-field blast loads. This research focuses on the evaluation of box girder bridges under blast loads. The objective of this research is to develop analytical and numerical models to predict the damage level in a concrete deck under blast loading and the corresponding dynamic response of the damaged bridge system. The numerical analysis starts from the verification of blast pressure in the free air using explicit LS-DYNA with the Arbitrary Lagrangian Eulerian (ALE) system of equations, followed by predicting the damage level on concrete panels under different charge weights and standoff distances and finally evaluating the dynamic response of bridge superstructure using the predominant damage levels. In addition, an analytical formulation will be presented to predict damage level of concrete structures under blast loading. Key parameters were studied during the analysis, such as the weight of the charge, the standoff distance, and concrete deck properties. Preliminary simulation results compared well with existing experimental blast test data on concrete panels for predicting the damage level. Simple analytical models for predicting the spalling/breaching of concrete walls under blast are development and will be refined using the numerical parametric study. An Artificial Network model (ANN) for predicting the concrete damage under near field blasts is also developed based numerical simulations of 125 slab blast configurations. The results compared reasonable well with existing empirical methods.
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