The pier of a bridge crossing the river is susceptible to vessel impact that may lead to bridge failure. To reliably assess pier dynamic response during the collision accident and design the bridge piers to resist such impact efficiently, the impact force histories should be accurately defined. In this paper, a 5,000DWT bulk carrier is modeled by explicit nonlinear software LS-DYNA. Meanwhile, a FE model of ship-rigid wall collision is developed and its impact force histories as well as impact force-displacement curves are analyzed in detail. A quasi-static method is employed to obtain the nonlinear static relationships between crush force and depth of ship-bow. In combination with static and dynamic deformation energy under various impact velocities, the dynamic crush stiffness is taken account into ship-bow stiffness during the collisions. In addition, a 2-DOF simplified interaction model is presented to calculate ship impact efficiently, which includes two mass points and two spring elements. Based on the finite element software Midas civil, the dynamic responses of a specific pier obtained from explicit finite-element method (LS-DYNA) and the simplified model are compared, respectively. According to the analysis result, the range of application for the simplified model is discussed.
Accidental ship collision is an important consideration in designing bridge structures across navigable waterways. The high kinetic energy of passing ships will pose a serious threat to bridge structures. It was noted (Cowan, 2007) that many waterways have relatively shallow channels, and therefore are unable to accommodate large-draft vessels. It has been noted in the literature (Larsen, 1993) that, on average, at least one serious ship collision occurs per year. For example, Michael (2018) pointed out that an empty 35,000 DWT bulk carrier collided with one of the support piers of the Sunshine Skyway Bridge in the USA in 1980, which lead to the collapse of bridge and 35 people losing their lives. Sha (2012) indicated that in 2007, a cargo vessel ploughed into the Jiujiang cable-stayed bridge in Guangdong, China, causing the collapse of two side spans. During the above ship-bridge collisions, significant lateral loads imparted to pier structures leads to its collapse. Therefore, engineers must account for lateral ship impact forces when designing bridge structures over navigable waterways.
