Research On Load Standard And Reliability Of Light Wharf Structures

Recently, the port engineering construction has achieved rapid development. A great many of wharves have been built in eastern coastal area, which have promoted the trade between China and other countries.However, because the carrying ability of existing structures is obviously insufficient with the demand of energy increasing, more wharf constructions need to be constructed. At present, most of aktological coastline has been developed already and new wharves can be built only in deep-sea areas. With the increase of the water depth, the wind, the wave and current loads, the deficiencies and defects of traditional wharf structures have been displayed, so a new wharf structure need to be studied. Based on this background, the 'Researching on the construction technology of shallow rock-based Light wharf in the offshore deep-water port' is supported by the National 863 project. As a part of this project, the reliability index of light wharves has been studied in this paper to meet the requirement in unified standard of reliability design for port structures.The main content can be summarized as follows:(1)According to the energy conservation principle, the mechanical model of mooring force is established, in which the deformation of light wharves is taken into account. Comparing with the traditional method which doesn't consider the wharf deformation, the deviation of calculation results is evaluated. Consequently, the mean coefficient and the variation coefficient for the computing model of mooring force are estimated.(2) The wave load and the current load for light wharves are statistically analyzed according to the existing statistics.The mean coefficient and the variation coefficient for the wave load and the current load are present, respectively. The probability distribution of wave loads is studied with Monte-Carlo method.(3) The ship impact force is statistically analyzed, when the elastic deformations of the hull and the pier structure as well as the nonlinear deformation of the fender are taken into account. Based on the simulated results, the distribution of ship impact forces which is characterized by the bimodal distribution can be expressed as the combing probability density function of the beta distribution and the normal distribution. The corresponding parameters of the probability density function can be estimated with the maximum likelihood method. The mean coefficient and the variation coefficient are calculated, respectively. (4) The bearing capacity of the rock-socketed piles which are made of concrete filled steel tubular is statistically analyzed. The mean coefficient and the variation coefficient of the bearing capacity for these piles are calculated in this paper.(5) According to the partial coefficients of load and resistance and the design expressions in China National Offshore oil and gas industry standards and Port engineering design of steel structures, the reliability index of the light wharves in different load combinations is calculated using the statistical results, respectively. The analysis results shows that the reliability index of light wharves designed by the load standard and the material partial coefficients given in China National Offshore oil and gas industry standards is low in all, and the reliability index of the light wharf, which are designed by the existing provision of the port engineering structures about the load standard and the material partial coefficients,can meet the requirements of uniform standards for the wharf reliability.(6) Based on the stochastic process theory, the fatigue reliability index of the light wharf is calculated under wave actions.Form analysis results, it can be seen that the fatigue reliability index of the wharf structures can meet the security requirements.