Abstract
This paper examines the tsunami wave forces acting on the I- girder bridges using the two numerical simulation methods, because many I-girder bridges were washed away by the tsunami flow generated by the 2011 off the Pacific Coast of Tohoku earthquake. In this paper the effects of the forces due to the air confined between the I-girder and tsunami flow surface investigate using the one-phase flow analysis taken into account for the water only as well as the two-phase flow analysis considering the water and the air effects. It is found that the effects of the forces by the confined air on the I-girder bridges are significant.
