Effects of Air Blast Loading on a Pier
An experimental program designed to study the effects of air blast loading on a pier is described. A pier model was tested in a six foot diameter horizontal shock tube under four different test situations simulating pier on a beach with water, pier on a dry beach in a Mach reflection region, pier in deep water, and a pier on a dry beach in a region of regular reflection. The model was subjected to various shock overpressures in each of the four test situations. Transient pressure distributions on the pier are investigated and it is found that a pier on a dry beach in a region of Mach reflection results in the most severe uplift pressure loads due to the air blast. A two-dimensional analysis based on Whitham's diffraction theory predicts higher uplift loads at low to moderate pressures and lower loads at higher pressures than were observed. Discrepancies between theory and experiments are attributed to three-dimensional effects and other geometric complications which are not accounted for in the theoretical analysis. The presence of water apparently results in waves splashing on the underside of the pier. It is possible that this can result in uplift forces exceeding those induced by the air shock. This effect needs further study. (Author).