不同失效模式下抗震RC框架结构延性分析

发布时间：2018-01-22 08:42

本文关键词： 失效模式 RC框架结构 Pushover分析塑性铰延性系数　出处：《长沙理工大学》2014年硕士论文　论文类型：学位论文

【摘要】：强震作用下,框架结构的延性变形能力与它的失效模式密切相关。5.12汶川地震后的震害调查发现,大量现浇钢筋混凝土(RC)框架结构的破坏形式为柱端破坏较梁端破坏严重,框架呈现出“强梁弱柱”的失效模式。而按我国建筑抗震设计规范所预期的“强柱弱梁”失效模式在RC框架中未能实现。从震害中可以看出,以“强梁弱柱”失效模式破坏的框架延性明显要比“强柱弱梁”失效模式下的框架延性差。按我国建筑抗震规范设计时,弹塑性地震力降低系数R对设防烈度地震作用的折减实际上决定了结构的屈服水准和延性需求的大小。而我国规范对不同延性能力的结构均取用相同的R值,即R=2.86。根据R-μ-T关系,这使得某些“强梁弱柱”失效模式下的框架延性能力达不到规范所预期的延性需求,从而导致基于现有规范设计的RC框架结构偏于不安全。本文针对此问题,完成的核心工作如下：(1)本文研究发现“强梁弱柱”导致框架延性差的现象与RC框架柱设计可靠性较低有关。为了阐明此现象的原因,对比分析了随机偏心距下我国2010版与2001版抗震规范RC大偏压柱抗震承载力可靠指标。结果表明了按我国2001版抗震规范设计的RC大偏压柱抗震承载力可靠指标取值偏低是影响结构延性的重要因素。(2)在SAP2000中建立有、无现浇楼板的框架结构模型分别来模拟罕遇地震作用下“强梁弱柱”与“强柱弱梁”两种不同的失效模式。根据Pushover分析得到的结构基底剪力-顶点位移曲线、能力谱和需求谱曲线以及结构的塑性铰发展过程,对比两种不同失效模式下延性系数的变化规律并进行R-μ关系分析,进而揭示当“强柱弱梁”失效模式较难实现时我国抗震设计规范采用定值R=2.86的不足。
[Abstract]:Under strong earthquake, the ductile deformation ability of frame structure is closely related to its failure mode. The failure of a large number of cast-in-place reinforced concrete (RC) frame structures is more serious at the end of columns than at the end of beams. The frame shows the failure mode of "strong beam and weak column", but the failure mode of "strong column and weak beam" as expected in the code of seismic design of our country can not be realized in RC frame, which can be seen from the earthquake damage. The ductility of frame with "strong beam weak column" failure mode is obviously worse than that with "strong column weak beam" failure mode. The reduction of elastic-plastic seismic force reduction coefficient R actually determines the yield level and ductility demand of the structure, and the same R value is used for the structures with different ductility capability in our code. According to the R- 渭 -T relation, the ductility capacity of some frame under the failure mode of "strong beam and weak column" can not reach the expected ductility requirement of the specification. As a result, the RC frame structure designed based on the existing specifications is less secure. This paper aims at this problem. The main work of this paper is as follows: 1) in this paper, it is found that the poor ductility of frame caused by "strong beam and weak column" is related to the low reliability of RC frame column design. In order to clarify the reason of this phenomenon. The reliability index of seismic bearing capacity of RC columns with large eccentric load under random eccentricity of China 2010 edition and 2001 edition seismic code is compared and analyzed. The results show that the RC large eccentric columns are designed according to the earthquake resistant code of 2001 edition of China. The low reliability index of aseismic bearing capacity is an important factor affecting the ductility of the structure. (. 2) in SAP2000. The model of frame structure without cast-in-place slab is used to simulate "strong beam weak column" and "strong column weak beam" under rare earthquake respectively. According to the Pushover analysis, the shear-vertex displacement curve of the base of the structure is obtained. The capacity spectrum and demand spectrum curves and the plastic hinge development process of the structure are compared, and the R- 渭 relation is analyzed by comparing the ductility coefficient of the two different failure modes. Furthermore, it is revealed that when the failure mode of "strong column and weak beam" is difficult to realize, China's seismic design code has the disadvantage of adopting fixed value R ~ (2.86).
【学位授予单位】：长沙理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU375.4

【参考文献】