Dynamic response and performance of cable-stayed bridges under blast load: Effects of pylon geometry

The air blast that is generated by the explosion of bombs or fuel tankers on or adjacent to a bridge can cause severe structural damage, and may result in partial or full collapse of the bridge. The dynamic response and structural performance of buildings under blast has been the subject of several studies, with considerably less attention being paid to the assessment of bridges under extreme blast loading scenarios. To reduce the computational expense of conducting blast analyses on large or complex bridges, the numerical sub-structuring technique is used in current practice. However, the simplifying assumptions adopted in these sub-structuring methods can lead to erroneous results. Accordingly, this study attempts to simulate numerically the dynamic response of an entire cable-stayed bridge subjected to blast loading using the LS-DYNA explicit finite element code. Based on best practice available in the literature, the blast load estimation, material modelling and detailed numerical simulation are carried out and the response of a cable-stayed steel bridge (designed according to minimum requirements of the Australian Bridge Standard) under blast loads ranging from a small to large detonation at different positions above the deck and near pylon are obtained. Furthermore, the potential effects of blast loads on different structural components with a focus on the cross-sectional geometry of the pylons are investigated.