烈度及设防结构烈度评定的讨论

A discussion on seismic intensity and intensity assessment for fortified structures

随着我国地震工程学的发展,烈度的应用范围渐渐发生了变化。通过整理半个多世纪的历史地震震害数据,发现整体趋势是,低烈度区的同类结构基本完好比例增加,其他破坏等级的比例下降,高烈度区同类结构的毁坏比例增加;收集近些年发生的汶川地震、芦山地震和鲁甸地震的部分震害数据,发现同一烈度区,设防、未设防的和不同设防等级的结构震害差别较大。如果烈度表达的是地震后果,则据这些后果平均水平判定的烈度应有不同,反证了烈度的含义是通过震害反映的地震作用。因此,借助不同建筑类型、不同设防等级的结构判定烈度时,需要相对统一的标准。由于我国丰富的震害资料来源于未设防结构,建议通过某个烈度下的不同设防标准、各类结构、各震害等级的平均震害指数和(或)破坏比与未设防同类结构的平均震害指数和(或)破坏比的统计关系,建立未设防结构对应的平均震害指数和(或)破坏比的调整系数,可据设防结构震害判定烈度。

With the development of earthquake engineering in China,the application scope of intensity has gradually changed.From the collected seismic damage data over more than half a century,it is found that in low-intensity regions,the proportion of similar building structures in basically intact state increased,and the proportions of other damage states decreased;while in high-intensity regions,the proportion of similar building structures in complete damage state increased.From the seismic damage data of Wenchuan earthquake,Lushan earthquake,and Ludian earthquake in recent years,it is found that in the same intensity area,the damages of fortified structures,unfortified structures,and structures with different fortification intensities are quite different.If the intensity represents the earthquake consequences,the intensity evaluated by the average level of earthquake damages should be different,thus implying that the meaning of intensity is the seismic action reflected by earthquake damage.Therefore,when we determine the intensity according to different types and different fortification levels of structures,a relatively unified standard is needed.Since the abundant damage data in China are from unfortified structures,it is suggested to establish the adjustment coefficients of average damage index/damage ratio corresponding to unfortified structures based on the statistical relationship between the average seismic damage index and(or)damage ratio of different fortification standards,various structures,and seismic damage levels of structures under a certain intensity and the average seismic damage index and(or)damage ratio of similar structures without fortification.The intensity could be determined by the damages of fortified structures.