Study on Partial Factors and Combination Value Coefficients for Uniform Temperature Action of Large-Span Structures

Abstract

The closure temperature refers to the temperature at which a structure forms an overall constrained structural system, also called the initial temperature. A reasonable closure temperature can avoid large additional stresses caused by excessive air temperature changes in large-span structures. To study the thermal action of the closure temperature on a structure, a probability distribution function of uniform temperature action is proposed. The effect of closure temperature is studied by introducing an adjustment coefficient. The partial factor and combination value coefficient of thermal action are presented, and their reliabilities are verified by the first-order second-moment method. The results show that with increasing adjustment coefficient, the probability distribution of thermal action tends to be uniformly divergent, the partial factor of thermal action increases, and the combination value coefficient decreases. The optimal closure temperature times are in March, April, October, and November for six cities in China. In this case, an adjustment coefficient of 0.3, a partial factor of 1.5, and the combination value coefficient of 0.45 are recommended. In addition, the partial factor of 1.5 and the combination value coefficient of 0.45 can be verified by reliability verification, which is more economical and reasonable with regard to ensuring safety.