大型火力发电厂钢筋混凝土横向框排架主厂房动力特性试验研究

对1／7大型火力发电厂三跨三榀钢筋混凝土横向框排架子空间模型，分别用激振法和柔度矩阵法进行模型结构动力特性试验，研究该结构的前三阶周期和振型，同时根据拟动力试验中结构的位移反应，求得在不同破损阶段模型结构的动力特性，最后根据相似关系得出原型结构的动力特性。     

大型火力发电厂主厂房动力特性分析

为了有效地提高主厂房的抗震能力,增强其安全性,在通用有限元软件SAP2000中建立了相应的线弹性结构模型,用以大型火力发电厂研究结构的动力特性,包括振型、薄弱层分布、质量分布、刚度分布;从体系层面上考察了结构形式的抗震性能是否合理,以及有无可优化的可能,同时为主厂房的大震设计和工程应用提供强有力的依据。     

型钢混凝土框排架结构主厂房拟动力实验研究

针对高烈度区大容量火电厂主厂房不适于应用钢筋混凝土框排架结构和钢支撑钢排架结构的情况,提出了采用新型型钢混凝土框排架混合结构体系.以1000MW机组电厂主厂房为原型,按1/7进行缩尺的3跨3榀框排架子结构进行空间模型的拟动力试验,研究了在水平地震作用下模型结构的裂缝发展规律及破坏机制、结构的滞回特性及变形性能、框排架结构协同工作性能等.研究结果表明:在地震加速度0.1g地震波作用下结构满足"小震不坏"的要求,在0.4g时满足"大震不倒"的要求;结构弹塑性层间位移角限值为1/95;排架结构的设计剪力应不小于整体结构7%的基底总剪力等.     

猴子岩高面板坝振动台模型试验——大坝结构动力特性研究

利用大型振动台模型试验,测得了猴子岩高面板堆石坝缩尺模型坝的动力特性参数,包括大坝结构的自振频率、阻尼比和振型系数等;分析了多种因素对坝体动力特性的影响规律;根据模型试验相似率推算得到原型坝的相应动力特性参数。研究表明:大坝结构有相对稳定的振型;坝体的动力特性参数值受激振白噪声强度和振动历史等因素影响;水库蓄水使得模型坝结构自振频率小幅提升。这些试验结果和研究结论,可以为该坝的动力分析提供基本资料和定性参考。     

高温气冷堆核电厂建筑结构采用不同有限元模型的模态分析对比研究

建立有限元模型是核电厂建筑结构模态分析的重要前提。本文以某高温气冷堆核电厂建筑结构为原型，在分析方法相同的前提下，建立2种不同模型（Solid模型和Shell模型），并对这2种模型进行模态分析。重点分析、对比2种模型的自振频率和振型图，计算分析表明:Solid模型与Shell模型相比，计算得到的结构自振频率值较高，但两者的差异很小，前30阶自振频率相对误差小于3.4%；2种模型的计算结构振型基本一致。研究结果可为核电厂抗震性能分析和设计提供参考。     

不同比例钢-混凝土混合结构高层建筑动力相似关系试验研究

模型试验的动力相似理论是结构抗震试验技术中的一个基础性研究课题。本文设计实现了1/10、1/20和1/30三个不同比例的钢-混凝土混合结构高层建筑的振动台模型试验。通过对三个模型试验结果的对比研究,对钢-混凝土混合结构高层建筑的动力相似关系进行了初步探讨。试验结果表明,按照本文的动力模型的设计施工及试验要求进行的不同比例钢-混凝土混合结构高层建筑的振动台试验,在自振频率、振型、加速度放大系数、楼层最大位移、楼层剪力等动力特性和动力反应方面具有较好的相似性。试验结果一方面说明对这三个模型采用的动力相似关系和制作方法是合理的,另一方面也说明了对钢-混凝土混合结构房屋采用较小的1/30比例进行振动台试验是可行的。     

混合结构振动台模型试验研究与计算分析

为研究混合结构的整体抗震性能,本研究以一个Ⅷ度区的LG大厦为原型,制作了1／20的整体模型,在同济大学土木工程国家重点实验室进行振动台试验,以考察地震动频谱及地震强度对混合结构地震反应的影响,了解混合结构体系的抗震性能、地震反应和破坏特征．本文还利用纤维模型建模对混合结构整体抗震性进行了非线性分析计算,并将计算结果与振动台试验数据进行对比分析,试验和计算结果表明：外钢骨框架-内混凝土核心筒混合结构具有较好的抗震性能．     

混合结构体系高层建筑模拟地震振动台试验研究

随着现代建筑高度的不断增加,混合结构体系在超高层建筑中逐步广泛应用,因此对该结构体系在地震作用下的破坏机理和抗震性能展开深入的研究是一项有意义的工作。本文对一混合结构体系复杂超高层建筑进行1／35的模型模拟地震振动台试验,分析模型结构的动力特性和不同烈度地震作用下加速度、位移和应变反应,然后根据相似关系推算出原型结构的动力特性和反应,研究其在各水准地震作用下的破坏机理和破坏形式,最后对原型结构设计提出若干建议。     

钢筋混凝土框排架结构在多维地震作用下的空间性能分析

针对钢筋混凝土横向框排架、纵向框架-剪力墙结构的某火力发电厂主厂房,建立此类不规则结构在双向水平地震作用下的振型分解反应谱方法。建立不同形式地震波作用下的结构空间整体计算模型,通过弹塑性时程分析,分别进行结构单向及水平双向地震反应分析,统计单双向地震作用效应比值,对抗震规范中的地震效应组合公式进行修正,获得了具有实用价值和理论意义的成果。     

外型钢砼框架—内置型钢框架钢筋砼核心筒混合结构抗震性能试验研究与分析

(超)高层建筑结构一定程度上可代表城市、地区的经济发展水平,其结构体系的选择、承重构件的类型及其连接对其使用功能至关重要。随着我国经济的快速发展,可以预测在今后相当长一段时间内,中国将是(超)高层建筑发展的主要阵地。由于高度超限,抗侧力体系多种多样,其适用范围及适用高度均有所不同,目前还很难形成系统完整的、有针对性的规范、标准等作为设计依据。更需注意的是,一些抗震设防区域或高烈度区也出现了(超)高层建筑结构,且此高度范围的建筑基本均未受到相当强度的地震洗礼。因此,为确保此类建筑结构在地震区的安全可靠,为此类结构抗震设计提供普遍意义上的设计依据,对其抗震性能的研究尤为重要。目前国内外对(超)高层建筑结构,特别是地标性建筑的抗震设计主要根据静、动力试验完成分析,辅以数值模拟完成整体结构的分析作为结构设计的主要依据。本文将采用上述手段对可适用于(超)高层建筑的混合结构体系主要进行如下研究:(1)提出一种新的(超)高层建筑体系,即:外型钢混凝土框架—内置型钢框架的钢筋混凝土核心筒混合结构体系。根据相似原理设计出1:10的模型结构,并进行了地震模拟振动台试验研究;(2)结合振动台试验结果,对该体系中出现的薄弱楼层处的内置型钢框架的组合核心筒体进行了1:2模型的拟静力试验研究;(3)初步探讨了该组合核心筒体的非线性力学性能。论文具体开展并完成了以下工作:(1)提出"外型钢混凝土框架—内置型钢框架钢筋混凝土核心筒"混合结构,探讨其用于(超)高层建筑作为结构抗侧体系的可行性。根据现行规范、规程设计了"外型钢混凝土框架—内置型钢框架钢筋混凝土核心筒混合结构",利用ETABS软件进行了该类结构体系的原型结构整体分析及截面设计。(2)根据相似原理,依据原型结构的基本设计信息,完成了1:10大比例整体模型结构的设计,获得了模型中主要构件的截面设计信息。(3)对该类混合结构模型进行了地震模拟振动台试验,系统分析了整体模型结构在不同类型、不同强度水平的地震动作用下楼层的动力响应,研究了不同工况下模型结构的破坏机理、外框架与核心内筒之间的协同工作性能及整体模型结构的薄弱层位置等,并根据相似关系讨论了对应的原型结构的动力响应及其抗震性能。(4)在振动台试验研究基础上,对内置钢框架钢筋混凝土核心筒体进行了1:2模型结构的拟静力试验。深入研究了该类组合筒体的刚度及承载力变化、耗能机制、滞回特性、变形特点及破坏机理等。进一步分析了内置型钢框架对钢筋混凝土核心筒的承载能力及延性的影响;讨论了内置型钢框架与混凝土间的相互作用及协同工作性能。(5)采用大型建筑结构有限元分析程序STRAT对该内置型钢框架核心筒进行了大震非线性分析及抗震性能研究。上述研究的目的是研究本文所提出的混合结构体系整体抗震性能及其主要抗侧部分—内置型钢框架核心筒体的抗侧能力,探讨该类混合结构在(超)高层建筑结构,特别是地震区高层建筑结构中应用的可行性。本文的研究旨在抗震试验分析的基础上,对该类混合结构体系的综合抗震性能进行全面的分析讨论,对该类结构在地震区的应用提供分析基础,为该类结构体系相应的技术标准、规程的编制与制定提供参考依据,为我国(超)高层建筑结构的发展提供技术保证。     

Dynamic characteristics of a base isolated building from ambient vibration measurements and low level earthquake shaking

Ambient vibration tests were conducted on a base-isolated apartment building in Takamatsu, Japan, to determine the mode shapes and the associated natural frequencies and damping ratios at very low levels of excitation. The latest developments in signal analysis for modal decomposition are used to analyze the ambient response data. A finite element model of the building and isolators was calibrated and refined using the experimental results from the ambient vibration tests. This model was then used to simulate the recorded response of the building under excitation from a small earthquake. The finite element model, calibrated by ambient vibration data and the low level of earthquake shaking, provides the starting point for modelling the non-linear response of the building when subjected to strong shaking.     

Effects of infill walls and floor diaphragms on the dynamic characteristics of a narrow‐rectangle building

Most buildings in Singapore are lightly reinforced concrete structures, which are mainly designed for gravity loading only, because Singapore is an island country located in a low‐to‐moderate seismic region. The dynamic properties of a typical high‐rise residential building with a long, narrow rectangular floor plan are studied using both experimental and numerical methods. The effects of the brick infill walls and the flexible diaphragms on the dynamic characteristics of the building are discussed in detail. The results from the ambient vibration tests are correlated with the numerical results of three different finite element models with different levels of sophistication. They include a bare frame model, a frame model with brick infill walls, and a frame model with both brick infill walls and flexible diaphragms. The dynamic properties of the third model match very well with the measured results in terms of both the natural frequencies and the mode shapes. The correlation results demonstrate the respective effects of the brick infill walls and the flexible diaphragms on the dynamic characteristics of the narrow‐rectangle building structure. Copyright © 2006 John Wiley & Sons, Ltd.     

Comparisons between ambient and forced vibration experiments

The ambient and forced vibration techniques for testing full-scale structures are critically compared. Both methods, based on small level excitation, may be used to determine many mode shapes and frequencies of vibration and the corresponding damping values, with adequate accuracy for most purposes. The two techniques give mutually consistent results. The mode amplitudes determined by ambient and forced vibration tests show systematic departure for high modes and near the top levels of buildings tested. This phenomenon is attributed to the participation of all mode shapes and is a consequence of excitation by a concentrated force near the top of a building and at a frequency differing by only a few per cent from a natural frequency of vibrations. A new way of showing the effect of unwanted modes on the response near resonance of the mode being sought is developed. It is particularly useful for the analysis of steady, forced vibration tests of structures using eccentric mass vibration generators.     

应县木塔环境振动试验

对于复杂的塔状古建筑物,建立一个合适的简化的数学模型是不易实现的。与强迫振动试验相比,环境振动试验比较简单、方便,所确定出的小振幅水平下的木塔结构动力特性具有足够的精度。本文首先结合应县木塔结构环境振动测试实例对环境振动测试方法作了简要介绍,并采用随机信号数据频域分析方法对测试数据进行了分析,确定木塔结构的自振频率。同时,依据不同测点在固有频率处响应的比及零迟时互相关函数确定木塔结构的振型。最后,本文依据自功率谱和互功率谱采用半功率点法计算各振型的阻尼比。本文分析结果表明,在两水平方向上木塔的振动特性存在些微差异,第一振型阻尼比较第二振型阻尼比大。     

Finite element analysis of structure-borne vibration from high-speed train

Finite element analyses were used to investigate the behavior of the building vibration induced by high-speed trains moving on bridges. The model includes the bridge, nearby building, soil and train. Finite element results indicate that trainload frequencies are more important than the natural frequencies of bridges and trains for building vibrations. If the building natural frequencies approach to the trainload frequencies, which equal an integer times the train speed over the compartment length, the resonance occurs and the building vibration will be large. Moreover, the vibration shape is similar to the mode shape of the resonance building frequency. To isolate the building vibration induced by moving trains, this paper investigates three common types of foundations, which include the extension of retaining walls, pile foundation and soil improvement around the building. Soil improvement around the building is the best way to reduce the building vibration both in horizontal and vertical directions.     

Evolution of modal characteristics of a mid-rise cold-formed steel building during construction and earthquake testing

Vibration-based structural identification is an essential technique for assessing structural conditions by inferring information from the dynamic characteristics of structures. However, the robustness of such techniques in monitoring the progressive damage of real structures has been validated with only a handful of research efforts, largely due to the paucity of monitoring data recorded from damaged structures. In a recent experimental program, a mid-rise cold-formed steel building was constructed at full scale atop a large shake table and subsequently subjected to a unique multi-hazard scenario including earthquake, post-earthquake fire, and finally post-fire earthquake loading. Complementing the simulated hazard events, low-amplitude vibration tests, including ambient vibrations and white noise base excitation tests, were conducted throughout the construction and the test phases. Using the vibration data collected during the multi-hazard test program, this paper focuses on understanding the modal characteristics of the cold-formed steel building in correlation with the construction and the structural damage progressively induced by the simulated hazard events. The modal parameters of the building (i.e., natural frequencies, damping ratios, and mode shapes) are estimated using two input–output and two output-only time-domain system identification techniques. Agreement between the evolution of modal parameters and the observations of the progression of physical damage demonstrates the effectiveness of the vibration-based system identification techniques for structural condition monitoring and damage assessment.     

云南漾濞地震大理某高层建筑结构地震响应观测数据初步分析

2021年5月21日21时21分至22时32分,云南漾濞先后发生了M5.6级、M6.4级、M5.0级和M5.2级地震,位于大理的某高层建筑结构地震反应观测台阵获取了这4次地震的结构动力响应,观测数据同步性好,数据质量高。该高层建筑为框架剪力墙结构,地上26层,地下1层,三分量加速度测点共8个分别位于建筑的第1层、4层、7层、10层、13层、17层、20层和25层,数据实时传输至中国地震局工程力学研究所燕郊数据中心。本文对结构台阵的观测记录进行了初步分析,绘制建筑结构观测楼层的三向绝对加速度及其傅里叶幅值谱,检验数据同步性和质量,通过滤波和积分得到相对速度和相对位移,利用功率谱方法分析得到频率响应函数,并利用复模态指数函数方法得到两水平方向前三阶模态频率和振型。通过4次地震结构模态频率和振型的初步对比结果表明:主体结构基本完好,这与现场调查结果吻合。该结构台阵获取的前震、主震和余震反应记录,为后续开展深入的模态参数分析、地震损伤识别以及研究框架剪力墙结构的振动特性和抗震性能提供了宝贵数据。     

Ambient vibration measurements on a cable-stayed bridge

An extensive programme of full-scale ambient vibration tests has been conducted to measure the dynamic response of a 542 m (centre span of 274 m) cable-stayed bridge—the Quincy Bayview Bridge in Illinois. A microcomputer-based system was used to collect and analyse the ambient vibration data. A total of 25 modal frequencies and associated mode shapes were identified for the deck structure within the frequency range of 0–2 Hz. Also, estimations were made for damping ratios. The experimental data clearly indicated the occurrence of many closely spaced modal frequencies and spatially complicated mode shapes. Most tower modes were found to be associated with the deck modes, implying a considerable interaction between the deck and tower structure. No detectable levels of motion were evident at the foundation support of the pier. The results of the ambient vibration survey were compared to modal frequencies and mode shapes computed using a three-dimensional finite element model of the bridge. For most modes, the analytic and experimental modal frequencies and mode shapes compare quite well, especially for the vertical modes. Based on the findings of this study, a linear elastic finite element model appears to be capable of capturing much of the complex dynamic behaviour of the bridge with very good accuracy, when compared to the low-level dynamic responses induced by ambient wind and traffic excitations.