[摘要] 关键构件中震弹性或中震不屈服的设防目标，作为一种加强措施在抗震设计中已经得到了应用。然而，工程实践表明按小震不坏设计得到的截面配筋率有时往往要大于中震不屈服的配筋率。在详细剖析有地震效应荷载组合公式的基础上，用图表和工程实例说明了中震不屈服对截面配筋的影响。进一步从抗震承载力调整系数，线性叠加原理和以概率理论为基础的设计极限状态等方面，对中震不屈服做出进一步评价。笔者认为目前工程界采用小震弹性分析，中震放大系数和荷载效应组合来实现薄弱部位或重要部位构件中震不屈服的设计方法，与当前的抗震设计理论是有矛盾的。中震不屈服是中震可修设防目标中的一种状态，表示震后建筑物恢复使用需要修理的程度。结构工程师应采用非线性分析验算构件中震时是否屈服。

[关键词] 小震不坏; 中震不屈服

Abstract: Currently, the target objective of unyielding during the design earthquake is defined and has got application to the key components in seismic design, as the measurement to enhance their strength. The target is reached by using the method of the load combination and the magnification factor equal to the ratio of the design earthquake and minimum considered earthquake effects. However, analysis results of the engineering projective shows that the reinforcement contents may be unexpectedly less than those obtained by the method called un-damage during the minimum considered earthquake which is recommended by the Chinese codes. This was explained in detail by using charts obtained from the formulae of load combination stipulated in GB 50011-2001 and JGJ 93-2002. Furthermore, the definition was discussed from the viewpoints such as the adjusting factor for seismic bearing capacity, the principle of linear superposition and design theory of ultimate state. The above concept of design-earthquake-unyielding of key components does not comply with the Chinese seismic design theory. In fact, it is the performance point B in the performance curves defined by ATC-40 or ASCE 41-06, which should be assessed using non-linear analysis method, static or dynamic.

Key words: un-damage in minimum considered earthquake; unyielding in design earthquake