抗震设计中结构的性能等级与设计性能安全指数

通常根据结构的破坏程度可以将结构的破坏划分为：基本完好、轻微破坏、中等破坏、严重破坏、倒塌等5个阶段。根据这5个阶段，本文将结构在地震过程中的性能极限状态划分为：功能连续极限状态、破坏控制极限状态、控制损失极限状态和防止倒塌极限状态，并以此作为划分结构性能等级的标准。定义结构失效概率的自然对数的负值为设计性能安全指数，通过计算结构失效概率对各构件可靠指标的一阶偏导数的方法，求出结构的设计性能安全等级。这种方法可以考虑建筑结构构件、建筑非结构构件以及其它非结构构件的性能，而且同时可以考虑结构系统总体效应的影响，因而能够比较全面地反映结构的抗震性能等级。

Performance gradation and performance safe index of structures in seismic design

According to the damage degree of structures, the damage state can be divided into five levels as:nearly intact, minor damage, moderate damage, serious damage and collapse. Based on the five levels, the performance limit states are divided into four stages: the function consecutive limit state, the damage control limit state, the loss control limit state and the collapse prevention limit state, and the division criteria of structural performance are established. The safe index of design performance is defined as the negative natural logarithm of structural failure probability in this paper. The safe grade of design performance is got by calculating the one-order partial derivative of the structural failure probability to the reliable indication of every structural element. Because the method can consider the performance of the building structural elements, the building non-structural elements and other non-structural elements, as well as the effect of the whole structure, the safe index of design performance can relatively reflect the seismic performance gradation.