Calculate Structural Design Checking Point Of Maximum Likelihood Method

Reliability is an important indicator to measure the structural safety.In the course of the reliability study, the calculation method which bases on probability theory has been a key part of the oretical research all long.Currently, the commonly methods of structural point reliability are mainly first-order second-moment method, second-order second-moment method, second–order fourth-moment method, response surface method, Monte-Carlo method and stochastic finite element method etc.Especially, the JC method in the first-order second-moment method, the design point calculations demand random variable that must obey the normal distribution, while non-normally distributed random variables must be converted to normal distribution and then calculate design point; At the same time, reliable indicator and design point calculation coupled with each other, which not only affects the calculation speed, but also affects the calculation accuracy.For these reasons, according to the principle of maximum likelihood function and based on the design point physical meaning, a design point calculation new method—maximum likelihood method was proposed, and a specific formula computing design point and reliability of index was established. Through a detailed analyse and a large number of specific examples, proved that, the method not only fully consided the true information on the various random variables, but also improved the calculation method of checking points, making independent random variables subject to random distribution of cases can calculate design point; solved the mutual coupling problem in JC method, making the design point and reliability index calculation process independent; combined with orthogonal transformation method, the relevant random variables subject to arbitrary distribution of structural design point and reliability index could be calculated.