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  周錫元^1,2   曾德民¹   高曉安¹
  （1 中國(guó)建筑科學(xué)研究院  北京 100013；   2 北京工業(yè)大學(xué)  100022）

[提要]  對(duì)現(xiàn)行建筑抗震設(shè)計(jì)規(guī)范中三個(gè)設(shè)防水準(zhǔn)的概率含義進(jìn)行了討論。指出除基本烈度地震以外，另外兩個(gè)水準(zhǔn)的概率含義是不明確的，只能從平均意義上去理解。根據(jù)規(guī)范中考慮的三個(gè)概率水準(zhǔn)的設(shè)防烈度之間的平均相互關(guān)系，建議了一種可以用于估計(jì)不同服役期結(jié)構(gòu)抗震設(shè)防烈度的簡(jiǎn)便方法。這樣確定的設(shè)防烈度雖然不能很好反映當(dāng)?shù)氐膶?shí)際情況，但是可以反映設(shè)防烈度隨服役期限變化的一般趨勢(shì)，故可作為確定一般工程設(shè)防烈度的參考。此外，還討論了建立與三水準(zhǔn)設(shè)防相對(duì)應(yīng)的基本加速度和設(shè)計(jì)反應(yīng)譜放大倍數(shù)。
[關(guān)鍵詞]  抗震設(shè)計(jì)  預(yù)期服役期  重現(xiàn)期  結(jié)構(gòu)重要性

The probabilistic meanings of three levels of earthquake protection in seismic design code for buildings are discussed. It is pointed out that except basic design earthquake intensity the probabilistic definition of the two levels of earth-quake protection is ambiguous that can only be understood in average meaning. On basis of mutual relations among three level probabilistic earthquake protection intensities, which are considered in seismic design code,  a simplified method for estimating design basic intensity of structures with different service period and acceptable hazard level is presented. The estimated design intensity corresponding to different return period in this way is unable to reflex the real situation of the local seismisity of the considered site, but gives a general assessment of the basic design intensity. Hence it can be used as reference for determining design intensity of normal structures.  In addition, the basic design accelerations and amplification factors in accordance with three level design intensities are also discussed.
Keywords:  seismic design; expected service period; return period; structural importance