【作者】 周莉莉；

【导师】 白绍良；

【作者基本信息】 重庆大学 ， 结构工程， 2009， 硕士

【摘要】 R -μ规律既是基于强度的抗震设计中确定水平设计地震作用的关键因素,又是基于性态的抗震设计理论的主要依据。因此,合理的R -μ规律是保证结构抗震安全性的关键所在。国内外研究者已对单自由度非弹性体系的R -μ- T规律作了广泛的研究,结论具有较好的一致性。但实际工程中的多高层结构由于受塑性机构类型、结构超强及多振型等多因素影响,其动力反应特征远比单自由度体系复杂,所以需要考察R -μ规律在多自由度非弹性体系中的适用性。近年来虽有少数研究成果,但仍缺少对这一适用性的明确结论。在这一大背景下,本文主要完成了以下研究工作:①总结和评述到目前为止已经完成的单自由度体系和多自由度体系R -μ规律的研究成果;②采用新思路选波,从美国加利福尼亚大学Berkeley分校太平洋地震工程研究中心(PEER)数据库下载合适的地面运动记录;③设计三个周期不同的单自由度体系,选择七档不同的地震力降低系数取值,通过非线性动力反应分析计算对应的位移延性μ值,初步验证单自由度体系的R -μ规律;④以按中国规范设计的0.4g区钢筋混凝土多层框架为例,把多层框架等效成单自由度体系,在相当于该区大震强度水准的多条地面运动输入下对多自由度体系和等效单自由度体系分别进行非弹性动力反应分析。通过考察两者在相同地震力降低系数取值下不同层面的延性需求间的差异,初步验证从单自由度体系获得的R -μ规律在多自由度体系中的适用性。通过上述研究工作,本文初步获得以下主要结论:①国内外研究者提出的单自由度体系R -μ- T规律的主要研究成果表现出良好的一致性。在探索多自由度体系的R -μ规律时,这些研究者通常着眼于将单自由度体系的R -μ规律进行修正后用于多自由度体系,多数是从特定算例出发寻求多自由度体系R的修正系数,未能从理论上根本解决多自由度体系的R -μ关系问题。②初步验证在多条地震波输入下计算得到的单自由度体系R -μ规律基本符合以往研究者提出的公式。对自振周期较长时算例与以往公式间存在的差异还有待进一步研究。③多自由度体系的结构延性需求小于等效单自由度体系,初步认为单自由度体系的R -μ规律在中等周期的多自由度体系中是适用的。除了层间位移角偏大楼层的部分梁铰外,多自由度体系的梁铰转角延性需求普遍小于对应的单自由度体系,柱铰的转角延性基本上都小于等效单自由度体系。初步认为在地震力降低系数R取值相同的情况下,可以用单自由度体系的位移延性系数μ来近似估计多自由度体系的延性需求。同时认为在三个延性层面中,多自由度体系塑性铰的转角延性与单自由度体系单一塑性铰的转角延性更具可比性。更多还原

【Abstract】 The R -μrelationship is not only the key factor in determining lateral design seismic force for force-based seismic design, but also the chief parameter for performance-based seismic design. So the proper R -μrelationship is the key factor to ensure the seismic security.Domestic and foreign researchers have comprehensively studied the R -μ- T relationships of single-degree-of-freedom inelastic systems and drawn similar conclusion. However, dynamic response characteristics of multi-rise and high-rise buildings in practice projects are more complex than that of single-degree-of-freedom inelastic systems due to the influence of potential hinge mechanisms, structural overstrength and higher modes, so R -μrelationship has to be verified whether it can be used in multi-degree-of-freedom inelastic systems. Recently several research findings reported on it, but none of them given definite conclusions on the applicability of R -μrelationship.Based on this background, the main research work finished in this thesis is as follows:①Summary and commentary of the main research findings of R -μrelationships for single- and multi-degree-of-freedom systems which have been so far finished.②Suitable ground motion records are downloaded from Berkeley Pacific Earthquake Engineering Research Center (PEER) database, which adopt new ideas.③Three single-degree-of-freedom systems are designed with varied fundamental period, then seven different force reduction factors are selected and the corresponding values of displacement ductilityμare calculated through nonlinear dynamic response analysis. So the R -μrelationships of single-degree-of-freedom systems are initial examined.④A multi-story reinforced concrete frame in earthquake intensity 0.4g zone is designed conforming to Chinese codes. Then the multi-storey structure is equivalent to a single-degree-of-freedom system, and the inelastic dynamic response analyses of the multi-degree-of-freedom system and the equivalent single-degree-of-freedom system when subjected to several ground motions in majoy earthquake intensity 0.4g zone are finished. Through the research of discrepancy between two systems on ductility demand of different levels with the same force reduction factor R , review the applicability of the R -μrelationship acquired from single-degree-of-freedom systems in multi-degree-of-freedom systems preliminarily have been verified.From the finished research work above, the main conclusions can be drawn preliminarily as follows:①The main research findings of the R -μ- Trelationships of single-degree-of-freedom systems proposed by domestic and foreign researchers are consistent. Researchers often focus on amending the R -μrelationship of single-degree-of-freedom systems to use in multi-degree-of-freedom systems, most of them seek for the modification factor of multi-degree-of-freedom systems from the specific examples. So the R -μtheoretical relation problems of multi-degree-of-freedom systems has not been ultimatly solved.②It is verified that the R -μrelationship of single-degree-of-freedom systems calculated after a number of seismic wave inputting is consistent with formulas proposed by previous researchers. It requires further study to eliminate the discrepancy between examples in this article and the previous formulas when natural vibration period is longer.③The structure ductility demand of multi-degree-of-freedom systems is less than the equivalent single-degree-of-freedom systems. The preliminary view is that the R -μrelationship of single-degree-of-freedom systems at the moderate period is suitable for multi-degree-of-freedom systems. The rotation ductility demand of beam hinges and column hinges of multi-degree-of-freedom systems is generally less than the equivalent single-degree-of-freedom systems, except some beam hinges on the story whose drift is larger. It is preliminary advised that the displacement ductility factorμof single-degree-of-freedom systems can be used to approximately estimate the ductility demand of multi-degree-of-freedom systems when two systems have the same force reduction factor R . And considering the three ductility levels, the rotation ductility of plastic hinges of multi-degree-of-freedom systems is more comparable with the rotation ductility of single-plastic hinge of single-degree-of-freedom systems.更多还原