共查询到20条相似文献，搜索用时 156 毫秒
1.
本文给出了一种改进的模态pushover方法,对竖向不规则结构进行抗震性能评估。通过考虑不规则结构高振型的影响,利用模态pushover方法将结构简化为不同的等效单自由度体系,并对其进行弹塑性时程分析,将所得到的结果进行组合,得到原结构的楼层位移和层间位移等性能指标。由于结构处于屈服阶段与处于弹性阶段时的各节点变形的关系有显著区别,因此对于进入塑性阶段的振型,采用屈服后的各节点变形关系计算位移变形响应,将计算得到的各个振型结果组合得到整体结构的位移。通过四个算例分析,表明改进的方法所得到的结果更加接近于弹塑性时程分析的结果,证明此方法能够有效地应用于竖向不规则结构的抗震性能评估与计算。 相似文献
2.
基于位移的结构静力弹塑性分析方法的研究 总被引：7，自引：0，他引：7
本文系统介绍了基于位移的一般结构静力弹塑性(pushover)分析方法、自适应结构静力弹塑性(pushover)分析方法,指出了基于力的结构静力弹塑性(pushover)分析方法与基于位移的结构静力弹塑性(pushover)分析方法的差别。应用各种结构静力弹塑性(pushover)分析方法对一7层和15层框架剪力墙结构进行了计算与比较分析。算例结果表明,应用基于位移的一般结构静力弹塑性(push-over)分析方法对结构的抗震性能进行评估时,不受高阶振型的影响,结果更加准确合理。 相似文献
3.
本文在已有的研究基础上,结合我国现行的抗震规范（GB50011—2001）和地震作用统计参数,提出了pushover分析中结构体系抗力曲线的保证率计算方法。以pushover分析所得的塑性铰出现次序和最终数量作为结构主要失效模式,同时考虑了结构抗力以及地震作用的随机性对结构体系抗力曲线的影响,借助于主要随机变量的灵敏度分析,得到了确定性pushover分析曲线的保证率。框架结构算例给出了本文方法的计算结果,并用重要抽样法进行了检验。 相似文献
4.
钢筋混凝土框架结构体系抗震可靠度及其抗力衰减影响分析 总被引：1，自引：0，他引：1
结构体系可靠度分析面临的主要问题是失效模式多,但通过pushover分析方法在一定情况下可以得到结构的最弱失效模式。本文将结构体系抗力等效为与结构特定损伤状况相关的结构的顶点位移,结构的地震作用效应由pushover分析及能力谱法求得。考虑结构体系抗力随机性的主要影响因素以及地震作用的随机性,分别求得了结构抗力及地震作用效应的概率分布参数,通过一次二阶矩方法求得了结构体系可靠度,并进一步研究了结构层数变化及耐久性退化因素对结构体系可靠度的影响。研究发现,结构体系的抗震可靠度水平随着结构层数的增加有减小的趋势,结构体系的抗震可靠度水平随着结构使用期增加而降低,降低幅度与薄弱层个数有关,薄弱层越多,降低幅度越大。 相似文献
5.
将结构前两阶振型各自等效为单自由度,采用模态pushover分析确定各等效单自由度的屈服强度系数和延性系数,然后由反应谱计算各阶振型耗散能量需求,利用各振型能量分布曲线,求得各层耗散能量需求,叠加得到各层地震总能量需求,据此确定耗能装置的类型及设计参数.运用该方法对9层钢框架进行了设计,并通过非线性动力分析进行了验证,结果表明该方法精确度符合实际工程需求. 相似文献
6.
扭转不规则结构水平侧向力分布模式与pushover分析 总被引：1，自引：0，他引：1
水平侧向力分布模式的施加问题是合理进行pushover分析的关键环节。对于可以简化为平面模型的结构,传统的水平侧向力分布模式表现出较好的适用性,但对于因扭转不规则而导致必须采用空间模型的结构则并不适用。为此,针对扭转不规则结构的水平侧向力分布模式问题,并基于该类结构的地震响应特征,通过引入水平侧向力调整系数和水平侧向力分配系数,提出了扭转不规则结构改进的水平侧向力分布模式。对一具有典型扭转不规则特性的空间钢框架结构分别进行改进分布模式下的pushover分析和IV类场地典型地震动作用下的弹塑性时程分析,计算结果显示:改进分布模式下的pushover分析体现出扭转效应对结构反应的影响,并在一定程度上反映出更多的结构抗震信息,验证了所提出模式的可行性,说明pushover分析法也同样适用于扭转不规则结构。 相似文献
7.
本文通过能量法研究了钢筋混凝土筒体结构的抗震性能。文中采用振型分解法按等效单自由度体系求解筒体结构的滞回输入能;用pushover法分析了滞回耗能在结构层间的分布规律及结构自身的耗能能力;根据楼层滞回耗能与弹塑性层间位移的关系求出了薄弱层的弹塑性位移。对一高层钢筋混凝土框架-筒体结构在7度罕遇地震下的抗震性能进行了评估,通过与非线性动力时程分析的对比,证明了方法的可行性。 相似文献
8.
考虑高振型影响的结构层间位移能力谱分析方法 总被引：5，自引：0，他引：5
工程界普遍采用的能力谱分析方法是建立在结构单自由度简化假设基础上，利用结构基本振型来进行能力分析。虽然此简化假设可以为工程界提供一种简便的分析方法，但从其分析效果来看，简化方法并不能很好地反映结构真实地震反应。高振型对结构局部变形的影响在分析结构动力反应特性中是很重要的因素，不应忽略掉。基于上述对现有能力谱分析方法不足之处的考虑，从提高结构能力谱分析方法的准确性出发，本文在Chopra能力谱分析方法的基础之上，根据我国振型分解反应谱思想，在能力谱分析方法中引入了结构高振型的影响分析，并提出了考虑结构高振型影响的结构层间位移能力谱分析方法的一般步骤。通过平面框架结构体系的算例分析，说明上述推荐方法在改进能力谱分析精度上的有效性。 相似文献
9.
结构动力灵敏度分析中的几个问题 总被引：3，自引：0，他引：3
结构动力灵敏度分析是进行抗震结构优化设计和考虑参数不确定性进行动力可靠性分析的基本步骤。本文就结构动力分析中几个常用的计算过程进行灵敏度分析研究,给出了Choleskey分解矩阵及其它常用数学变换的灵敏度计算表达,分析了振型灵敏度的传递作用,指出对于一般的剪切型结构可以不考虑振型及振型参与系数的灵敏度,从而使问题大为简化。本文还讨论了结构动力反应与各基本参数的灵敏度之间的关系,提出了直接通过结构地震反应得到灵敏度谱的设想。作者认为,通过大量的统计分析可以得到工程上实用的地震反应灵敏度谱。 相似文献
10.
本文通过能量法研究了钢筋混凝土简体结构的抗震性能。文中采用振型分解法按等效单自由度体系求解简体结构的滞回输入能；用pushover法分析了滞回耗能在结构层间的分布规律及结构自身的耗能能力；根据楼层滞回耗能与弹塑性层间位移的关系求出了薄弱层的弹塑性位移。对一高层钢筋混凝土框架-简体结构在7度罕遇地震下的抗震性能进行了评估，通过与非线性动力时程分析的对比，证明了方法的可行性。 相似文献
11.
An improved modal pushover analysis procedure for estimating seismic demands of structures 总被引：7，自引：4，他引：3
The pushover analysis （POA） procedure is difficult to apply to high-rise buildings, as it cannot account for the contributions of higher modes. To overcome this limitation, a modal pushover analysis （MPA） procedure was proposed by Chopra et al. （2001）. However, invariable lateral force distributions are still adopted in the MPA. In this paper, an improved MPA procedure is presented to estimate the seismic demands of structures, considering the redistribution of inertia forces after the structure yields. This improved procedure is verified with numerical examples of 5-, 9- and 22-story buildings. It is concluded that the improved MPA procedure is more accurate than either the POA procedure or MPA procedure. In addition, the proposed procedure avoids a large computational effort by adopting a two-phase lateral force distribution.. 相似文献
12.
Modified consecutive modal pushover procedure for seismic investigation of one-way asymmetric-plan tall buildings 总被引：1，自引：1，他引：0
The effects of higher modes and torsion have a significant impact on the seismic responses of asymmetric-plan tall buildings.A consecutive modal pushover(CMP) procedure is one of the pushover methods that have been developed to consider these effects.The aim of this paper is to modify the(CMP) analysis procedure to estimate the seismic demands of one-way asymmetric-plan tall buildings with dual systems.An analysis of 10-,15-and 20-story asymmetric-plan buildings is carried out,and the results from the modified consecutive modal pushover(MCMP) procedure are compared with those obtained from the modal pushover analysis(MPA) procedure and the nonlinear time history analysis(NLTHA).The MCMP estimates of the seismic demands of one-way asymmetric-plan buildings demonstrate a reasonable accuracy,compared to the results obtained from the NLTHA.Furthermore,the accuracy of the MCMP procedure in the prediction of plastic hinge rotations is better than the MPA procedure.The new pushover procedure is also more accurate than the FEMA load distribution and the MPA procedure. 相似文献
13.
An Erratum has been published for this article in Earthquake Engineering and Structural Dynamics 2003; 32:1795. The recently developed modal pushover analysis (MPA) has been shown to be a significant improvement over the pushover analysis procedures currently used in structural engineering practice. None of the current invariant force distributions accounts for the contribution of higher modes—higher than the fundamental mode—to the response or for redistribution of inertial forces because of structural yielding. By including the contributions of a sufficient number of modes of vibration (generally two to three), the height‐wise distribution of responses estimated by MPA is generally similar to the ‘exact’ results from non‐linear response history analysis (RHA). Although the results of the previous research were extremely promising, only a few buildings were evaluated. The results presented below evaluate the accuracy of MPA for a wide range of buildings and ground motion ensembles. The selected structures are idealized frames of six different heights: 3, 6, 9, 12, 15, and 18 stories and five strength levels corresponding to SDF‐system ductility factor of 1, 1.5, 2, 4, and 6; each frame is analysed for 20 ground motions. Comparing the median values of storey‐drift demands determined by MPA to those obtained from non‐linear RHA shows that the MPA predicts reasonably well the changing height‐wise variation of demand with building height and SDF‐system ductility factor. Median and dispersion values of the ratios of storey‐drift demands determined by MPA and non‐linear‐RHA procedures were computed to measure the bias and dispersion of MPA estimates with the following results: (1) the bias and dispersion in the MPA procedure tend to increase for longer‐period frames and larger SDF‐system ductility factors (although these trends are not perfect); (2) the bias and dispersion in MPA estimates of seismic demands for inelastic frames are usually larger than for elastic systems; (3) the well‐known response spectrum analysis (RSA), which is equivalent to the MPA for elastic systems, consistently underestimates the response of elastic structures, e.g. up to 18% in the upper‐storey drifts of 18‐storey frames. Finally, the MPA procedure is simplified to facilitate its implementation in engineering practice—where the earthquake hazard is usually defined in terms of a median (or some other percentile) design spectrum for elastic systems—and the accuracy of this simplified procedure is documented. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
14.
一种基于位移的改进静力弹塑性分析方法 总被引：6，自引：0，他引：6
静力弹塑性分析作为一种新的结构抗震性能评估方法，近些年得到很大的推广。本文在已有的研究基础上，通过一种基于位移控制的多阶振型组合的静力推覆分析，采用自适应的水平加载方式，考虑高阶振型的影响。对一中等高度的结构进行推覆分析，结果表明，与采用不变的水平菏载分布形式的一般静力推覆分析比较，基于本文Pushover分析所得的结构响应与非线性动力时程分析所得结构的响应更为近似，尤其在受结构高阶振型影响较明显的结构层间位移角及层间剪力方面，其结果同动力时程分析所得更为接近。 相似文献
15.
The modal pushover analysis (MPA) procedure, presently restricted to one horizontal component of ground motion, is extended to three‐dimensional analysis of buildings—symmetric or unsymmetric in plan—subjected to two horizontal components of ground motion, simultaneously. Also presented is a variant of this method, called the practical modal pushover analysis (PMPA) procedure, which estimates seismic demands directly from the earthquake response (or design) spectrum. Its accuracy in estimating seismic demands for very tall buildings is evaluated, demonstrating that for nonlinear systems this procedure is almost as accurate as the response spectrum analysis procedure is for linear systems. Thus, for practical applications, the PMPA procedure offers an attractive alternative whereby seismic demands can be estimated directly from the (elastic) design spectrum, thus avoiding the complications of selecting and scaling ground motions for nonlinear response history analysis. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
16.
模态静力非线性分析中模态选择的研究 总被引：18，自引：4，他引：14
本文应用模态静力非线性分析方法,对多个算例进行了静力非线性分析。比较分析了不同振型组合对计算精度的影响,对模态选择的参数进行了研究,提出采用模态质量参与系数进行模态选择的控制,为模态静力非线性分析方法的推广使用提供参考。另外,分析了结构基本周期对该方法计算精度的影响。 相似文献
17.
The N2 method has been extended in order to take into account higher mode effects in elevation. The extension is based on the assumption that the structure remains in the elastic range when vibrating in higher modes. The seismic demand in terms of displacements and storey drifts can be obtained by enveloping the results of basic pushover analysis and the results of standard elastic modal analysis. The approach is consistent with the extended N2 method used for plan‐asymmetric buildings. The proposed procedure was applied to three variants of three steel frame buildings used in the SAC project. The structural response was investigated for two sets of ground motions. Different ground motion intensities were used in order to investigate the influence of the magnitude of plastic deformations. The N2 results were compared with the results of nonlinear response‐history analysis, two other pushover‐based methods (modal pushover analysis (MPA) and modified MPA (MMPA)), and pushover analysis without consideration of higher modes. It was found that a considerable influence of higher modes on storey drifts is present at the upper part of medium‐and high‐rise structures. This effect is the largest in the case of elastic behaviour and decreases with ground motion intensity. The higher mode effects also depend on the spectral shape. The approximate methods (extended N2, MPA and MMPA) are able to provide fair estimates of response in the case of the test examples. Accuracy decreases with the height of the building, and with the intensity of ground motion. The N2 results are generally conservative. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
18.
This paper develops a modal pushover analysis‐ (MPA) based approximate procedure to quantify the collapse potential of structural systems. The computationally demanding incremental dynamic analysis (IDA) of the structural system is avoided by MPA of the structure in conjunction with empirical equations for the collapse strength ratio for the first‐mode single‐degree‐of‐freedom (SDF) system; higher modes of vibration play essentially no role in estimating the ground motion intensity required to cause collapse of the structure. Presented are collapse fragility curves for 6‐, 9‐, and 20‐story regular special moment‐resisting teel frames computed by the exact and approximate procedures, demonstrating that the MPA‐based approximate procedure requires only a small fraction (1% in one example) of the computational effort inherent in exact IDA and still achieves highly accurate results. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
19.
框架剪力墙结构模态静力非线性抗震分析方法研究 总被引：5，自引：2，他引：3
本文在模态pushover分析方法基础上推导建立了模态静力非线性分析方法,对一栋10层框架剪力墙结构进行了静力非线性分析,提出了目标位移求解的等效单自由度体系弹塑性时程分析迭代法,计算结果与相应时程分析结果进行了比较,表明两者吻合较好,验证了本文计算方法的有效性。另外,对同一结构,计算分析了在不同水平荷载模式下的静力非线性分析结果,比较不同荷载模式对计算结果的影响,为静力非线性分析方法的推广使用提供参考。 相似文献
20.
循环往复加载的地下结构Pushover分析方法及其在地震损伤分析中的应用 总被引：1，自引：1，他引：0
考虑到地震作用下地下结构往往受到双向往复荷载作用,本文提出了循环往复加载的地下结构Pushover分析方法.介绍了该方法的实施步骤、基本功能与特点.该方法考虑了地震作用下地下结构双向受力的特点,利用多点位移控制的推覆分析算法进行地震作用下正向加载-卸载-反向再加载的全过程分析.该方法将一次循环加载过程近似看作一次地震作用过程,提出了基于循环往复加载Pushover分析的损伤模型,避免了对土-结构整体模型进行复杂的动力相互作用分析;通过一次循环往复加载的Pushover分析,根据结构构件刚度的改变对结构损伤进行有效评估.结合实际工程进行算例分析初步验证了循环往复加载Pushover分析及地震损伤模型的有效性. 相似文献