Many stairs of buildings were destroyed badly in 5·12 Wenchuan earthquake. Subsequently,some technical measures were adopted in code for seismic design of buildings and technical specification for concrete structures of tall building. If an entire structure is constituted by the main portion and the statically determinate subsidiary portion that is supported by main portion,the load applied on subsidiary portion always gives rise to internal forces in main portion,but the load applied on main portion produces no internal forces in subsidiary portion. In other words,if stairs structure is the statically determinate subsidiary portion that is supported by main portion,the internal forces in stairs structure always are very weak. The statically determinate stairs or the stairs in which horizontal forces are statically determinate shall be adopted generally in not only concrete frame structure buildings but also all concrete-structure and all steel-structure tier buildings or tall buildings. The code and technical specification should state clearly such requirement.%5·12汶川地震时,许多楼房中的楼梯发生严重破坏. 此后,《建筑抗震设计规范》和《高层建筑混凝土结构技术规程》都采取了技术对策. 结构中若有基本部分又有支承于基本部分的静定附属部分,那么,附属部分的荷载使基本部分产生内力,但基本部分的荷载不会使附属部分产生内力. 换言之,如果楼梯是支承于整体结构的静定部分,楼梯结构的内力就总是很小. 不仅混凝土框架结构建筑,而且所有混凝土结构、钢结构的多层建筑或高层建筑,都应该普遍采用静定楼梯或者水平力静定的楼梯. 规范规程应该明确要求这样做.
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