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1.
《华南地震》2017,(4)
以矩形分布荷载模式的隔震悬臂铁木辛柯梁模型推导了隔震结构有害层间位移角及名义层间位移角的计算公式;通过某高层隔震剪力墙结构算例对其有害层间位移和无害层间侧移的分布规律进行研究,分别采用名义层间位移角和有害层间位移角对隔震结构进行优化控制设计,对比了两种设计方案的用钢量指标并通过大震非线性动力时程分析对两种设计方案上部结构的塑性损伤演化规律进行研究。研究表明:隔震剪力墙结构的最大名义层间位移和最大有害层间位移并不是出现在同一个楼层;以有害层间位移角作为目标函数的优化设计方案比原结构方案更具有经济性;罕遇地震作用下,整个上部结构的损伤分布较为均匀,这对于隔震结构的安全性是非常有利的。 相似文献
2.
以一个3跨4排柱建筑为例,对非隔震结构和隔震结构在竖向荷载作用下的内力分布特点进行了对比研究,其中考虑了隔震层顶部梁板结构的荷载、刚度以及结构的梁柱刚度比等因素的影响.研究中发现,与非隔震结构相比,隔震结构一层柱子的柱端弯矩明显增大,隔震层顶部梁的梁端弯矩与其倚载成正比等规律.同时提出了基于非隔震结构的隔震结构在竖向荷载作用下内力的计算方法和“隔震影响系数”的概念.即,隔震结构的内力等于非隔震结构的内力乘以“隔震影响系数”.其中还进一步对“隔震影响系数”的影响因素进行了定量研究,得出了“隔震影响系数”的计算公式.本文所提出的计算方法与隔震结构在水平地震荷载作用下的内力计算方法思路一致,因此,该方法也进一步完善了隔震结构的设计理论. 相似文献
3.
提出了一种用于水平成层场地地震反应分析的时域高阶显式算法. 首先,将覆盖土层和基岩划分为若干个切比雪夫谱单元,在模型底部设置多次透射人工边界;其次,以切比雪夫正交多项式构建高阶单元位移模式,通过高斯?洛巴托积分严格导出对角形式的切比雪夫谱单元集中质量矩阵,结合中心差分时域逐步积分格式,建立了高效的集中质量切比雪夫谱元波动模拟方法;最后,利用日本Kik-net强震台网提供的不同类型场地上获得的实际地震观测记录检验了本文方法的有效性. 该方法避免了传统切比雪夫谱元法由于具有一致质量矩阵形式而造成的计算效率不高的问题。数值结果表明,本文方法能够较好地预测Ⅰ1,Ⅱ和Ⅳ类场地在较弱地震和中等强度地震作用下的地面运动特征,每个波长内仅需布置少量单元即可取得较高精度的计算结果。 相似文献
4.
为研究基础隔震结构抗连续倒塌性能,以备用荷载路径法为基础,采用静力非线性Pushdown方法和静力线性方法对一栋典型的收进式竖向不规则钢筋混凝土基础隔震结构进行分析,从备用荷载路径的抗连续倒塌机制和需求能力比两个角度研究竖向不规则钢筋混凝土基础隔震结构的抗连续倒塌性能,为基础隔震结构抗连续倒塌设计提供参考;为进一步研究结构布置形式不规则性以及裙楼和塔楼层数变化对竖向不规则基础隔震抗连续倒塌性能的影响,分别建立塔楼布置不同、裙楼与塔楼层数变化的模型进行对比研究。研究表明:除角柱失效工况自身无法产生悬链线机制外,其余底层框架柱失效工况中备用荷载路径在整个推覆倒塌过程中均表现出明显的悬链线机制;当隔震支座失效时,由于隔震层水平刚度小,相邻支座无法提供足够的侧向约束作用而难以形成明显的悬链线机制;增加结构冗余度和备用荷载路径中参与荷载传递的构件数量可以有效提高剩余结构抗连续倒塌能力;除角柱和角支座外,隔震支座失效工况DCR值普遍大于对应位置底层框架柱失效工况,备用荷载路径中某些构件的失效风险相对较大。 相似文献
5.
基于Hilbert-Huang变换和随机子空间识别技术提出了两种土木工程结构的模态参数识别方法。方法一是基于Hilbert-Huang变换和自然激励技术,通过经验模态分解和Hilbert变换提取信号的瞬时特性,进而利用自然激励技术和模态分析的基本理论识别结构的模态参数;方法二是基于经验模态分解和随机子空间识别技术,通过经验模态分解对信号进行预处理,进而运用随机子空间识别方法处理得到的结构单阶模态响应以识别结构的模态参数。利用这两种方法,通过对一12层钢筋混凝土框架模型振动台试验测点加速度记录的处理,识别了该模型结构的模态参数。识别结果与传统的基于傅里叶变换的识别结果及有限元分析结果的对比验证了这两种方法的可行性和实用性。 相似文献
6.
对一基础隔震钢筋混凝土框架结构在无填充墙情况下进行了环境激励下的动力测试,重点利用Hilbert-Huang变换与随机减量技术相结合的方法识别了其模态参数,并与随机子空间识别法、有理分式多项式法识别的结果进行了对比。识别结果表明在环境激励下,基础隔震结构的基本周期远小于多遇和罕遇地震工况下设计计算的基本周期;等效黏滞阻尼比很小,近乎于基础固定模型。对隔震层阻尼特性的分析表明,环境激励下可以将基础隔震结构视为经典的比例阻尼系统。进一步以识别的模态参数为基准,采用优化的方法数值反演了环境激励下该结构隔震层的实际水平等效刚度,结果表明其值为多遇地震下计算刚度取值的10.75倍。 相似文献
7.
基于HHT的非线性结构系统识别研究 总被引：11，自引：2，他引：11
本文研究基于HHT的多自由度非线性结构系统识别方法。首先通过EMD分解得到结构的非线性模态(NNM),然后对非线性模态进行H ilbert分析,识别出结构的瞬时特征参数(瞬时振幅、瞬时固有频率等),进而由各参数间关系识别出非线性结构的类型。最后通过一个具有非线性刚度的两自由度剪切型建筑结构的数值模拟验证了该方法的有效性。 相似文献
8.
《地震工程与工程振动》2021,41(4)
以典型的四层、六层和八层LRB(铅芯橡胶隔震支座)基础隔震结构为研究对象,通过大量的弹塑性时程分析,对极罕遇地震作用下的地震响应特点进行了分析;采用参数化方法,研究了隔震系统的力学性能参数和上部结构屈服强度比的变化对LRB基础隔震结构抗震性能的影响。结果表明:在极罕遇地震作用下,LRB基础隔震结构上部结构首层的层间位移角和延性系数明显增大;延长LRB隔震系统的隔震周期或选择最优的特征屈服强度比,均可显著降低上部结构的塑性变形程度,但LRB屈服位移的变化对隔震结构的响应几乎无影响;LRB隔震系统参数确定后,隔震结构上部结构的损伤状态主要与上部结构力学性能参数中的屈服强度比相关,增大上部结构的屈服强度比,可以显著降低上部结构的层间位移角和延性系数,但是隔震支座的平均最大剪应变会增大,可以选用橡胶剪切模量大或者直径大、第二形状系数小的LRB隔震支座。 相似文献
9.
基于Hilbert-Huang变换和随机减量技术的模态参数识别 总被引：2，自引：0，他引：2
傅里叶分析的信号处理方法对非线性、非平稳信号的处理能力差,传统的模态参数识别方法也存在阻尼比识别精度不高的问题。基于Hilbert-Huang变换和随机减量技术提出了一种新的、实用的模态参数识别方法,首先对结构振动信号进行滤波处理和经验模态分解,得到若干阶本征模态响应,然后利用随机减量技术提取自由衰减响应,进而由Hilbert-Huang变换得到信号的瞬时特性,最后结合模态识别的基本理论识别结构的模态频率和模态阻尼比。为了验证这一方法的有效性,对12层钢筋混凝土框架模型振动台试验一测点的加速度记录进行了处理,识别了模态参数,识别结果与其它识别方法及有限元分析结果的对比表明该方法识别模态频率是可靠的,而模态阻尼比识别的精准性仍然难以确认。 相似文献
10.
将二硫化钼作为摩擦材料设计出一种带限位器的滑移隔震支座。根据多层框架结构变形的特点,给出适用于滑移框架隔震结构的计算模型,推导出层间滑移隔震结构的运动方程。运用SAP2000有限元软件建立一层间滑移框架隔震结构的有限元模型,对比分析El Centro地震波下摩擦系数和隔震层位置不同时隔震结构的地震反应。结果表明,上部结构的动力反应随摩擦系数的增加而不断增大,滑移隔震结构的减震效果逐渐减弱,但隔震层的滑移量却在不断减小;摩擦系数的选取应综合考虑减震效果和隔震层滑移量两个因素。随着隔震层的增高,结构的加速度反应和层间位移反应整体上呈增大趋势,隔震效果不断减弱,且隔震层的加速度值下部层比上部层要大得多,一层隔震和三层隔震时的变形主要集中于隔震层,而五层隔震时结构层间位移并未出现突变,说明隔震层设置在较高位置处对结构体系的影响较小。 相似文献
11.
The paper deals with the applicability of the extended N2 method to base‐isolated plan‐asymmetric building structures. The results obtained by the usual pushover analysis of a 3D structural model are further combined with the aid of linear dynamic (spectral) analysis to account for the dynamic effects caused by structural asymmetry. In the paper, the method has been applied to the seismic analysis of a mass‐eccentric four‐storeyed RC frame building isolated with lead rubber bearings. Three different positions of the center of isolation system (CI) with respect to the center of mass (CM) and the center of stiffness of the superstructure (CS) were considered. The response was analyzed for three different eccentricities, three different torsional to lateral frequency ratios of the superstructure, and two ground motion intensities. The stiffness of the isolators was selected for three different protection levels, which resulted in elastic as well as moderately to excessively damaged superstructure performance levels. The results are presented in terms of the top, base and relative displacements, as well as the stiff/flexible side amplification factors. A more detailed insight into the nonlinear behavior of the superstructure is given in a form of ductility factors for the flexible and stiff side frames. The results of the extended N2 method for selected lateral load distributions are compared with the average results of nonlinear dynamic analyses. It was concluded that the extended N2 method could, with certain limitations, provide a reasonable prediction of the torsional influences in minor to moderately asymmetric base‐isolated structures. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
12.
Application of subspace identification technique to long‐term seismic response monitoring of structures 
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下载免费PDF全文 This paper addresses the issue of structural system identification using earthquake‐induced structural response. The proposed methodology is based on the subspace identification algorithm to perform identification of structural dynamic characteristics using input–output seismic response data. Incorporated with subspace identification algorithm, a scheme to remove spurious modes is also used to identify real system poles. The efficiency of the proposed method is shown by the analysis of all measurement data from all measurement directly. The recorded seismic response data of three structures (one 7‐story RC building, one midisolation building, and one isolated bridge), under Taiwan Strong Motion Instrumentation Program, are analyzed during the past 15 years. The results present the variation of the identified fundamental modal frequencies and damping ratios from all the recorded seismic events that these three structures had encountered during their service life. Seismic assessment of the structures from the identified system dynamic characteristics during the period of their service is discussed. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
13.
S. S. Law 《地震工程与工程振动(英文版)》2009,8(1):103-114
A new method is proposed to assess the condition of structures under unknown support excitation by simultaneously detecting local damage and identifying the support excitation from several structural dynamic responses. The support excitation acting on a structure is modeled by orthogonal polynomial approximations, and the sensitivities of structural dynamic response with respect to its physical parameters and orthogonal coeffi cients are derived. The identifi cation equation is based on Taylor’s fi rst orde... 相似文献
14.
地震下结构振动的最优控制算法模型比较与改进 总被引：8，自引：0，他引：8
模拟地震激励输入结构的过程,将控制目标函数化解到每个时间步长上。用激励所产生的脉冲响应重新构造控制目标函数,直接从泛函变分出发,推导出了一种改进的最优控制算法,并用状态转移的数值方法加以实现。从概念上讲,本算法是一种更为合理的结构最优控制算法。算例表明,在相同控制能量下,本算法能更有效地削减响应峰值,且稳定性良好。 相似文献
15.
Vincent Crozet Ioannis Politopoulos Mingguan Yang Jean‐Marc Martinez Silvano Erlicher 《地震工程与结构动力学》2018,47(1):219-235
This article deals with sensitivity of the response of pounding buildings with respect to structural and earthquake excitation parameters. A comprehensive sensitivity analysis is carried out by means of Monte Carlo simulations of adjacent single degree of freedom impacting oscillators. This sensitivity analysis, based on Sobol's method, computes sensitivity indexes which provide a consistent measure of the relative importance of parameters such as the dimensionless main excitation frequency, the mass and frequency ratios of the structures, and the coefficient of restitution. Moreover, the influence of nonlinear behavior of the impacting structures is also considered. The consequences of pounding on the structures themselves are analyzed in terms of maximum force and nonlinear demand amplification compared with the case without pounding. As for the influence of pounding on the floor response spectra, the quantity of interest is the maximum impact impulse. The overall conclusions of this analysis are that the frequency ratio is the most important parameter as far as the maximum force and nonlinear demand are concerned. Regarding the maximum impact impulse, the mass and frequency ratios are, in general, the most influential parameters, the mass ratio being predominant for low frequencies of the oscillator of interest. 相似文献
16.
The viability of a complete structural characterization of civil structures is explored and discussed. In particular, the identification of modal (i.e. natural frequencies, damping ratios and modal shapes) and physical properties (i.e. mass and stiffness) using only the structure’s free decay response is studied. To accomplish this, modal analysis from free vibration response only (MAFVRO) and mass modification (MM) methodologies are engaged along with Wavelet based techniques for optimal signal processing and modal reconstruction. The methodologies are evaluated using simulated and experimental data. The simulated data are extracted from a simple elastic model of a 5 story shear building and from a more realistic nonlinear model of a RC frame structure. The experimental data are gathered from shake table test of a 2-story scaled shear building. Guidelines for the reconstruction procedure from the data are proposed as the quality of the identified properties is shown to be governed by adequate selection of the frequency bands and optimal modal shape reconstruction. Moreover, in cases where the structure has undergone damage, the proposed identification scheme can also be applied for preliminary assessment of structural health. 相似文献
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A fully automated design methodology based on nonlinear response history analysis is proposed for the optimum seismic design of reinforced concrete (RC) structures. The conventional trial‐and‐error process is replaced by a structural optimization algorithm that serves as a search engine capable of locating the most efficient design in terms of cost and performance. Two variations of the proposed design methodology are introduced. The first approach treats the optimum design problem in a deterministic manner, while in the second variation the optimum design is sought in the framework of a reliability‐based optimization problem. The reliability‐based approach seems to be a more rational procedure since more meaningful design criteria that correlate better with the performance‐based design concept can be adopted. Thus, the practice of using the mean annual frequency of a limit‐state being exceeded to assess the candidate designs is compared with the use of deterministic criteria. Both formulations take into consideration the structural response for a number of limit‐states, from serviceability to collapse prevention. The proposed design procedure is specifically tailored to the design of RC structures, where a preliminary design step of generating tables of concrete sections is introduced. In order to handle the large size of the tables, the concept of multi‐database cascade optimization is implemented. The final design has to comply with the provisions of European design codes. The proposed methodology allows for a significant reduction of the direct construction cost combined with improved control of the seismic performance under earthquake loading. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
19.
Earthquake simulator tests of a 1/6-scale nine-story reinforced concrete frame-wall model are described in the paper. The test results and associated numerical simulation are summarized and discussed. Based on the test data, a relationship between maximum inter-story drift and damage state is established. Equations of variation of structural characteristics (natural frequency and equivalent stiffness) with overall drifts are derived by data fitting, which can be used to estimate structural damage state if structural characteristics can be measured. A comparison of the analytical and experimental results show that both the commonly used equivalent beam and fiber element models can simulate the nonlinear seismic response of structures very well. Finally, conclusions associated with seismic design and damage evaluation of RC structures are presented. 相似文献
20.
A pushover procedure with a load pattern based on the height-wise distribution of the combined modal story shear and torsional moment is proposed to estimate the seismic response of 3D asymmetric-plan building frames. Contribution of the higher modes and torsional response of asymmetric-plan buildings are incorporated into the proposed load pattern. The proposed pushover method is a single-run procedure, which enables tracing the nonlinear response of the structure during the analysis and averts the elusiveness of conducting multiple pushover analyses. The proposed method has been used to estimate the response of two moment-resisting building frames with 9 and 20 stories. The obtained results indicate the appropriate accuracy and efficiency of the proposed procedure in estimating the trend of the drift profiles of the structures resulted from nonlinear time history analyses. 相似文献