In this study, the correlation between the fatigue equivalent stress and the stress cycle was considered using the copula function in the fatigue reliability assessment. In most earlier studies, the variables for the fatigue reliability function were assumed to be independent. However, based on the structural health monitoring (SHM) data in this study, they show that there are correlation properties in part of the variables. Hence, using the traditional method, the calculated fatigue reliability index is not accurate. For this reason, a new calculation method that considers the correlation between the variables was developed. The Gaussian copula was used to solve this problem because of its powerful connect function and concise expression. The study shows that there is a correlation between the fatigue stress and the fatigue stress cycle in the Nan-Xi Yangtze River Bridge. The values of the fatigue reliability index that consider the correlation between the variables are smaller than those calculated by the traditional method.

Weight, speed, axle space, and following distance of the vehicles are important factors that determine the live load for simply supported beam bridges. In this study, the effect of live load on simply supported bridges was investigated by considering these parameters. The parameters namely weight, speed, longitudinal following space, and vehicle occupancy ratio on different driving lanes are considered using different numerical models. Then, the random traffic flow is simulated using Monte Carlo method based on Nan-xi Yangzi River Bridge’s weigh-in-motion system data. Finite element models are established for six types of simply supported beam bridges with the span ranging from 6 to 40 m and transient analysis is simulated under the traffic loading. Subsequently, the maximum value distribution of live load for lifetime is obtained for the collected data by the method of extrapolation. This study shows that the mean value of the live load for the simply supported beam bridges under a random traffic flow is lower than the permissible design load as per American Association of State Highway and Transportation Officials; however, it is higher than the permissible design load as per BS5400, and it is 0.82 times the Highway-I standard load.

This paper presents an experimental study that sought to characterize the effect of corrosion and fatigue load on the behavior of reinforcing steel bars. The surface profiles of corroded steel bars and the relationship between fatigue life and corrosion morphology were investigated. First, the corrosion process was accelerated by applying external direct current. Next, fatigue tests were performed on uncorroded specimens and precorroded specimens, and the results are presented and analyzed. A method for calculating the three-dimensional (3D) corrosion morphology coefficient of corroded steel bar is proposed. The fatigue life of corroded bars is significantly reduced because of corrosion morphology, and a logarithmic linear relationship exists between fatigue life and the corrosion morphology coefficient. Considering the corrosion morphology of corroded steel bars, a method is provided to calculate the fatigue life of a corroded steel bar based on the properties of uncorroded steel bar and the 3D surface morphology coefficient of corroded steel bars. The prediction results for corroded steel bars agree well with the experimental observations.