多层偏心结构直接基于位移的抗震设计方法

A DIRECT DISPLACEMENT-BASED SEISMIC DESIGN METHODOLOGY FOR MULTI-LAYER ASYMMETRIC STRUCTURES

以往直接基于位移的抗震设计方法一般是以2-D平面内分析为前提的,不考虑平面外的影响。而对于多层偏心结构,由于地震下结构水平面内的反应具有很大的不规则性以及结构两水平方向具有空间耦合性,所以采用这种2-D设计方法具有一定的不合理性。针对此问题,提出了偏心结构直接基于位移的抗震设计方法,将偏心结构在地震作用下最薄弱的位置作为控制点,以该点在各地震设防水准下的限制位移为目标位移进行结构设计。详细介绍了该方法的步骤。该方法利用等效单自由度系统理论建立设计/分析模型,设计中为减少迭代次数,定义了结构竖向刚度调整系数,用以简化结构弹性刚度和强度的确定过程,从而实现设计结构在相应地震设防水准下满足预期位移的控制要求。最后通过一多层偏心结构的设计算例来检验该方法,并证明了该方法具有一定的准确性。

The classic displacement-based seismic design procedure depends on the 2-D structural analysis. But the procedure is inapplicable for multi-layer asymmetric structures for considering the imbalance responses and coupled characteristics of responses in the plane of asymmetric structures subjected to earthquake excitations. Therefore, an improved direct displacement-based seismic design method for multi-layer asymmetric structures is presented for the purpose that the procedure attempts to create structures with a specified limited displacement objective of the weakness places of structures under a specified level of seismic intensity. The implementing procedures of this method are introduced in details, in which the theory of equivalent SDOF system is used for simplifying the analysis, the adjustment coefficient of vertical stiffness of structures is defined to reduce the iterative design. A simple multi-layer asymmetric structure is designed for verifying the procedure. From the analysis of the example, the displacement responses of weakness places of the structure meet the expected limits under the specified level of seismic intensity. It is shown that the procedure developed in this paper may be used as an effective seismic design method for multi-layer asymmetric structures.