超高层结构弹塑性模拟中若干问题的讨论

Discussion on nonlinear time history analysis for super high-rise buildings

弹塑性动力时程分析方法是确定结构大震安全性的重要方法,也是性能化抗震设计的必要工具和必然趋势。本文基于超高层建筑结构弹塑性分析中累积的经验,对模拟和分析结果判断所遇到的问题提出一些见解,并结合某超高层结构案例的分析结果作为辅助论证。文中提出对连梁、巨柱等构件的模拟应抓住构件的受力和在结构中的作用等特征来简化计算模型,认为在软件还不能准确反映构件或材料细观破坏行为情况下不建议采用精细化的模型。由于结构进入塑性后周期会变长,故本文认为对弹塑性分析的基底剪力、层间位移角等应结合结构动力特性的变化及时程波的动力特性进行综合评判。基于我国规范的性能目标评判标准还有待完善。

Non-linear time history analysis is considered to be an important method to verify the structural performance under rare earthquake as well as the essential tool for performance based seismic design. Based on the experience of nonlinear time history analysis of high-rise buildings,this paper proposes some suggestions on the simulation and results assessment then verify them with the project examples. It is argued that the simulation of coupling beam,mega-column should comply with the characteristic and the mechanism of structural element and simplified the model correspondingly. It is suggested that if the program is not able to simulate the element or the material micro-failure process exactly yet,the fine-tuned model is not needed. Because the structure will become flexible after entering plastic stage,the verification of the index including base shear,storey drift ratio and so on should take account the change of dynamic property of the structural and the input earthquake wave. The performance criteria which suits Chinese code is still need to be developed.