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Aim at the difficulty in determining the dynamic load , dynamic problems were analyzed, including three mechanisms of the shipbuilding gantry crane of lifting、trolley running and cart running under the joint starting and braking by adopting the method for determining the dynamic load based on the vibration theory and the one for determining the dynamic load based on the virtual prototype.Dynamic models and virtual prototype model were established and the time-varying dynamic loads of mechanisms were determined under typical working conditions. The maximum dynamic load obtained provides a reference for the dynamic finite element analysis of the shipbuilding gantry crane.

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Damage accumulation and resistance decrease inevitably happen to bridge structures due to the effects of earthquakes, impact loads, wind load and corrosion during their service time. Once the damages of the key components accumulate to a certain level, they would spread promptly, causing the sudden destruction of the whole structure if not found and dealt with in time. So the structural damages would not only shorten the operation life of structure but also threaten the human lives and financial safety. Therefore, the technology of damage diagnosis of bridge structure holds supreme significance. This paper summarized the current research situation of the existing bridge diagnosis methods and analyzed the characteristics of each method through the reading and studying of the related material both domestically and internationally. Among those methods, only the diagnosis method based on load tests is the most direct and effective one for current bridge diagnosis, the diagnosis results of which shows higher reliability. And the structural dynamic characteristic method based on dynamic load tests could beautifully avoid the disadvantages of the static load tests, becoming the main development direction of rapid diagnosis of bridge. Furthermore, lastly it elaborated the analysis of the key problems of breaking through the development bottleneck of current rapid diagnosis methods of bridge, creating a solid foundation for the future research.

The essence of the axle coupling vibration in case of random bridge deck is random vibration, therefore, it is quite necessary to research the effect of vehicle impact on basis of statistic analysis. With some large concrete-filled steel tube arch bridge as the object, by applying a self-made analysis program on axle coupling vibration that was demonstrated by a dynamic test, a dynamic response analysis on axle was implemented for many groups of random roughness swatches. On basis of the analysis result, a statistic analysis was conducted for the dynamic impact effect of bridge under the conditions of different deck status and vehicle speeds, in the determination of vehicle speed and roughness, the impact factor obeys the normal distribution. The analysis result shows that, the level of deck status may apparently affect the mean value and the MSD(mean square deviation), the differences of vehicle impact factors in case of different assurance rates are large. It will effectively improve the reasonableness and scientificalness of the value of a vehicle impact factor to determine the impact factor according to the level of bridge importance and a statistic analysis method.