工程结构承载力极限状态与正常使用极限状态可靠度的比较分析

Comparison and analysis of reliability of engineering structures at ultimate limit states and serviceability limit states

讨论了工程结构承载力极限状态设计与正常使用极限状态验算之间区别,认为荷载标准值来源于在正常使用时人们对允许挠度和裂缝宽的感受;验证了正常使用极限状态下可靠指标β值小即表示对工程结构可靠性限制更严更安全的论断;通过对同一种判据,如挠度允许值可靠度比较,认为二者无比较意义;当二者采用不同判据时,如极限承载力与允许挠度,认为二者性质不同,可靠指标不能直接比较。

This paper discusses the difference between ultimate limit states design and serviceability limit states checking calculation of engineering structures and considers that the characteristic value of load comes from the feelings of people for allowable deflection and crack width during serviceability.It verifies the judgment that small β value of reliability index at serviceability limit states means more severe and safer restriction on the reliability of engineering structures.Through comparison of the same criterion such as the reliability of allowable deflection,both of them are considered not worth of comparison;when different criteria（such as ultimate bearing capacity and allowable deflection） are adopted for both of them,the two are different in nature,and their reliability indexes cannot be compared directly.