基于预设屈服模式的复杂结构抗震设计方法

Performance-based seismic design method of predetermined yield mode for complicated building structures

当前我国规范抗震设计思路主要是基于规则结构,要求耗能构件在罕遇地震作用下均匀进入塑性,这对于存在明显薄弱部位的复杂结构并不适用。为此,提出了一种预设屈服模式的抗震性能化设计方法。给出了该方法的基本设计流程,通过整体结构动力弹塑性分析方法获得真实的结构构件刚度折减系数,可提高复杂建筑结构设防烈度地震、罕遇地震反应谱分析的准确度。对带薄弱层的复杂高层建筑结构进行算例分析表明,预设屈服模式方法可实现对复杂结构抗震设计由现有规范对不规则的控制转变为对破坏模式的控制,同时能够有效避免复杂结构在超烈度地震下因薄弱部位失效而提前丧失承载能力的隐患,使结构安全储备得到提升。

The main seismic design concept in the current code allows regular structure members to dissipate energy uniformly when entering into the plastic stage. This design approach isn’t suitable for complicated building structures with obvious weak part. A performance-based seismic design method based on predetermined yield mode is proposed, and the basic design flow is provided. The stiffness reduction coefficient for structural members is calculated by nonlinear dynamic analysis of the entire structure, which can improve the accuracy of spectra analysis for moderate or rare earthquakes. A case study of a complicated high-rise building structure with weak parts shows that the seismic design concept for complicated building structures can be changed from irregularity control in the current code to failure mode control in the newly proposed seismic design method, and meantime, the risk of early loss of structural resistance due to failure of the weak parts is avoided, and as a result the level of safety of the complicated building structure is enhanced.