STUDY ON REDUCTION OF UPLIFT PRESSURE BY AIRBAG

Abstract

 Coastal structure which has floor slab such as jetty sometimes cannot avoid uplift pressure by tsunami or ocean wave due to its structural restriction of height. And it is also confirmed that impulsive uplift pressure is reduced when water hit the slab indirectly through enough quantity of air layer. Therefore, we suggested a countermeasure using an airbag like a paper balloon with a hall at the center of the bottom. Then we tested its reduction performance against the impulsive uplift pressure by hydraulic experiment with large and small models. Besides that, numerical calculation was also conducted to confirm effects of fabric property of airbag on the reduction performance. Experiment results show that setting airbag between water surface and slab can extend duration of impulsive uplift pressure and maximum pressure is reduced dramatically. And numerical calculation shows that rigidity and air permeability of fabric contributes to the reduction performance against the impulsive uplift pressure.