In the calculation of the forces between ship-bridge impacts, the influential parameters are needed to be identified. Based on the AIS (Automatic Identification System) analysis on vessel transit path of the bridges over Yangtze River, the influential parameters of the ship- bridge collision of transiting vessel are investigated. These influential parameters include the ship sailing information and static information, namely yaw angle, velocity, tonnage and the track of ships. For the correctness of probabilistic distributions of these parameters, the chi- square test is applied to modify the probabilistic distributions. The aberrancy angle and vessel velocity probabilistic models related with impact forces are established and also verified by goodness of fit test.
With the development of economy and technology, bridge construction has entered a new period. At the same time, marine transportation has been also developed; the velocity and tonnage of ship are increasing, and the navigational density of channel through bridges become larger. These aspects would increase the probability of ship-bridge collision. Hence, the risk assessment of ship-bridge collision for the safety of designed bridge is needed to be carried out to evaluate whether design of the bridge meets the safety requirement for anti-collision. The influential parameters of ship-bridge collision include the span arrangement of the bridge, track distribution, yaw angle, velocity, impact angle, displacement and the impact position of ships crossing bridge.
Many researchers have studied probabilistic risk for ship-bridge collision(e.g. Samuelides et al., 2008; Goerlandt et al., 2012). Traditional risk analyses of ship collision generally calculate the possibility of ship-bridge collision with empirical formula, which may be not appropriate to describe every scenario of the studied areas. The probability of collision and consequences are determined based on the traffic conditions, namely the actual information of vessels, such as the velocity, displacement and orientation. Nowadays, the normal distribution is often used to describe these influence parameters of ship- bridge collision (Dai, 2002). It was found that the impact scenario models have significant effect on the collapse probabilities of bridge (Kaarle et al., 2013). No well justified impact scenario models are available for every investigated area by now. The adequacy of currently available models for impact scenarios should be improved based on actual data, i.e. models linking the traffic conditions to the conditions at the moment of collision.
