Reliability Analysis of Long-Span Bridges Based on Combination of Response Surface Method and JC Method

For the long-span bridges, the structural reliability calculation is likely to be excessive due to the complex structural system, multiple random influential factors, and distinct structural nonlinearity. To address this issue, a reliability calculation method that combines the response surface method and JC method is proposed, in which the material random variables are first selected, and the function of the bridge structure is fitted using the response surface method based on the numerical simulation, and the JC method is used to normalize the non-normal random variable, at last, the improved first-order second-moment method is used to calculate the structural reliability index. The presented method has been applied to the Lingdingyang Bridge of Shenzhen-Zhongshan Link. The reliability of the suspension system of the bridge under extreme winds were analyzed. It is shown that the reliability of the suspension system of the bridge can meet the code requirements. The reliability index of the stiffening girder is between 7.98 and 11.21, smallest at the pylon bearings. The reliability index of the main cables is from 12.24 to 13.42, with that of the central-span main cable greater than that of side span. The realibility index of the hanger cables is within the range of 7.79 and 9.48, where the reliability index of the strengthened hanger cables is larger than that of the normal hanger cables. The reliability indexes of the suspension system of the Lingdingyang Bridge are compared with the suspension bridges of similar type, and the proposed method is proved having higher effectiveness. © 2022, Journal Press, China Railway Bridge Science Research Institute, Ltd. All right reserved.