The mechanics of ship impacts against bridges

The purpose of this paper is to present mathematical procedures for estimating the risk associated with ship collisions with bridges. The frequency part of the calculations is based on information related to the volume and the composition of the ship traffic in the vicinity of the bridge. This information is introduced in a mathematical model for estimation of the return period for collisions with bridge piers and girders.

A new mathematical model is thereafter presented for calculation of the energies released for crushing of structures given a specific collision scenario which may include a glancing blow between the ship and the bridge structure. This model is based on rigid body mechanics and well suited for inclusion in a probabilistic analysis procedure.

Finally, some empirical expressions are presented which relate the energy absorbed by crushing of ship structures to the maximum impact loads between the ship structure and a bridge pier or girder.