Calculation of structure coefficient in design of penstocks as subentry coefficient

Using Probability-based Limit States Design Method, according to subentry coefficient design expression, to carrying capacity limit state, designing expression of five subentry coefficient will be adopted. In the condition that the distribution of water weight in a pipe is log-normal distribution, and the maximum distribution is extreme distribution, Structure Coefficient in design expression was ascertained by the engineering experience calibration method and by the reliability analysis method.