Copula-based investigation of temperature-wind joint actions and effects on long-span cable-stayed bridges

The correlation between temperature and wind action is not always precisely considered in the design of large-span cable-stayed bridges, resulting in conservative designs. This study conducted structural temperature and wind tests on a cable-stayed bridge and obtained a 54-year long-term sample of bridge temperature and wind effects by converting meteorological station data. Monthly extreme values and corresponding values of effective temperature and wind action were selected and divided into heating and cooling period. Subsequently, the joint actions were derived based on Kendall’s return period after the joint distributions of the two actions were established using copula theory. Moreover, the bending moment and deflection of the pylon were calculated and discussed under the temperature-wind joint actions. The comparative analysis demonstrated that the actual reference wind speed would not exceed 50% of the specified values when the univariate temperature action characteristic proposed in the design specifications is applied. A comparable pattern is observed in the case of wind dominance, whereby the actual maximum and minimum effective temperatures are approximately 80 and 60% of the specified values, respectively. Compared to the effect of the fundamental combination as outlined in the General Code, the bending moment of the pylon is reduced by up to 6.33%, while the deflection is reduced by up to 10.31% when joint actions are applied.