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1.
Forced vibration field tests and finite-element studies were conducted on the Shahid Rajaee concrete arch dam in Northern Iran to determine the dynamic properties of the dam–reservoir–foundation system. The first forced vibration tests on the dam were performed with two different types of exciter units, with a limited maximum force, bolted on the dam crest for alternative in-phase and out-of-phase sequencing. Because of an insufficient number of recording sensors, two arrangements of sensors were used to cover sufficient points on the dam crest and one gallery during tests. Two kinds of vibration tests, on–off and frequency sweeping, were carried out on the dam. The primary natural frequencies of the coupled system for both symmetric and anti-symmetric vibration modes were approximated during on–off tests in two types of sequencing of exciters, in phase and out-of-phase, with a maximum frequency of 14 Hz. The principal forced vibration tests were performed at precise resonant frequencies based on the results of the on–off tests in which sweeping around the approximated frequencies at 0.1 Hz increments was performed. Baseline correction and suitable bandpass filtering were applied to the test records and then signal processing was carried out to compute the auto power, cross power and coherence spectra. Nine middle modes of vibration of the coupled system and corresponding damping ratios were estimated. The empirical results are compared against the results from calibrated finite-element modeling of the system using former ambient vibration tests, considering the dam–reservoir–foundation interaction effects. Good agreement is obtained between experimental and numerical results for eight middle modes of the dam–reservoir–foundation system. 相似文献
2.
Economic losses during past earthquakes are strongly associated with damage and failure to nonstructural equipment and contents. Among the vast types of nonstructural elements, one important category, is scientific equipment in biological or chemical laboratories. These equipment are often mounted on heavy ceramic bench‐tops of bench–shelf systems, which in turn may amplify the dynamic motions imposed. To investigate the seismic response of these types of systems, a series of shake table and field experiments were conducted considering different representative bench and shelf‐mounted equipment and contents. Results from shake table experiments indicate that these equipment are generally sliding‐dominated. In addition, the bench–shelf system is observed to be very stiff and when lightly loaded, has a fundamental frequency between 10 and 16 Hz. An approximate 50% reduction in the first and second fundamental frequencies is observed considering practical loading conditions. Insight into a broader range of system response is provided by conducting eigenvalue and time history analyses. Non‐linear regression through the numerical data indicate acceleration amplification ratios Ω range from 2.6 to 1.4 and from 4.3 to 1.6, for fixed–fixed and pinned–pinned conditions, respectively. Both the experimental and numerical results support the importance of determining the potential dynamic amplification of motion in the context of accurately determining the maximum sliding displacement of support equipment and contents. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
3.
结合某高精密设备平台基础隔振实际工程,基于UPFs(User Programmable Features)二次开发特点,提出考虑基础-地基-基础动力相互作用计算基础隔振分析的三维有限元方法。该方法首先将动力机器、周围地基以及高精密设备平台基础作为完整的研究对象,通过引入三维紧支黏弹性边界单元模拟半无限地基辐射阻尼效应和远场介质的弹性恢复性能,并在通用有限元软件ANSYS中实现。进而基于最小二乘方法回归分析得到振动衰减关系曲线,通过其与数值分析结果的对比验证计算模型的合理性。最后针对此工程场地条件建立隔振沟减振隔振措施的有限元模型,并对隔振沟影响因素的减振效果进行分析。计算结果表明,隔振沟的位置、深度以及长度是实际工程中需要考虑的重要因素,对其进行合理的选取可获得较好的隔振效果。 相似文献
4.
With the development and implementation of performance-based earthquake engineering, harmonization of performance levels between structural and nonstructural components becomes vital. Even if the structural components of a building achieve a continuous or immediate occupancy performance level after a seismic event, failure of architectural, mechanical or electrical components can lower the performance level of the entire building system. This reduction in performance caused by the vulnerability of nonstructural components has been observed during recent earthquakes worldwide. Moreover, nonstructural damage has limited the functionality of critical facilities, such as hospitals, following major seismic events. The investment in nonstructural components and building contents is far greater than that of structural components and framing. Therefore, it is not surprising that in many past earthquakes, losses from damage to nonstructural components have exceeded losses from structural damage. Furthermore, the failure of nonstructural components can become a safety hazard or can hamper the safe movement of occupants evacuating buildings, or of rescue workers entering buildings. In comparison to structural components and systems, there is relatively limited information on the seismic design of nonstructural components. Basic research work in this area has been sparse, and the available codes and guidelines are usually, for the most part, based on past experiences, engineering judgment and intuition, rather than on objective experimental and analytical results. Often, design engineers are forced to start almost from square one after each earthquake event: to observe what went wrong and to try to prevent repetitions. This is a consequence of the empirical nature of current seismic regulations and guidelines for nonstructural components. This review paper summarizes current knowledge on the seismic design and analysis of nonstructural building components, identifying major knowledge gaps that will need to be filled by future research. Furthermore, considering recent trends in earthquake engineering, the paper explores how performance-based seismic design might be conceived for nonstructural components, drawing on recent developments made in the field of seismic design and hinting at the specific considerations required for nonstructural components. 相似文献
5.
Performance-based seismic design of nonstructural building components:The next frontier of earthquake engineering 总被引：1，自引：1，他引：0
With the development and implementation of performance-based earthquake engineering,harmonization of performance levels between structural and nonstructural components becomes vital. Even if the structural components of a building achieve a continuous or immediate occupancy performance level after a seismic event,failure of architectural,mechanical or electrical components can lower the performance level of the entire building system. This reduction in performance caused by the vulnerability of nonstructural components has been observed during recent earthquakes worldwide. Moreover,nonstructural damage has limited the functionality of critical facilities,such as hospitals,following major seismic events. The investment in nonstructural components and building contents is far greater than that of structural components and framing. Therefore,it is not surprising that in many past earthquakes,losses from damage to nonstructural components have exceeded losses from structural damage. Furthermore,the failure of nonstructural components can become a safety hazard or can hamper the safe movement of occupants evacuating buildings,or of rescue workers entering buildings. In comparison to structural components and systems,there is relatively limited information on the seismic design of nonstructural components. Basic research work in this area has been sparse,and the available codes and guidelines are usually,for the most part,based on past experiences,engineering judgment and intuition,rather than on objective experimental and analytical results. Often,design engineers are forced to start almost from square one after each earthquake event: to observe what went wrong and to try to prevent repetitions. This is a consequence of the empirical nature of current seismic regulations and guidelines for nonstructural components. This review paper summarizes current knowledge on the seismic design and analysis of nonstructural building components,identifying major knowledge gaps that will need to be filled by future research. Furthermore,considering recent trends in earthquake engineering,the paper explores how performance-based seismic design might be conceived for nonstructural components,drawing on recent developments made in the field of seismic design and hinting at the specific considerations required for nonstructural components. 相似文献
6.
The characterization of the dynamic behavior of an arch dam, and its evolution throughout the structure's lifetime, provides important data for the safety control process. Forced vibration tests remain a reliable technique for this purpose. The Baixo Sabor dam is a 123 m high arch dam recently built in Portugal. Forced vibration tests were performed before and after the reservoir filling. Two techniques for forced vibration test are compared, discrete frequency scanning, the standard methodology, and continuous frequency scanning (sine sweep), a new proposed methodology, which allowed faster results without loss of precision. For the interpretation of test results two numerical models of the dam-reservoir-foundation system were built, and calibrated with the experimental data. A good match of numerical and experimental results was obtained for the six lowest frequencies and corresponding mode shapes. 相似文献
7.
地铁运行产生的环境振动超过一定值会影响人体健康,准确评价地铁运行引起的振动响应值意义重大。本文采用进口测振仪分别对青岛地铁3号线和上海地铁10号线进行现场测振,对数据进行处理得出振动加速度时程曲线,对测试数据进行Fourier变换得到相应的频谱曲线,将频谱曲线按1/3倍频程滤波转化为1/3倍频程谱,进而计算出分频振级平均值。通过加速度时程、频谱、1/3倍频程谱和分频振级的对比分析,结果表明:青岛地铁振动响应明显大于上海地铁,其分频振级已超过我国的环境振动标准,而上海地铁的分频振级基本上与我国的环境振动标准相当。 相似文献
8.
The potential application of tuned liquid column damper (TLCD) for suppressing wind-induced vibration of long span bridges
is explored in this paper. By installing the TLCD in the bridge deck, a mathematical model for the bridge-TLCD system is established.
The governing equations of the system are developed by considering all three displacement components of the deck in vertical,
lateral, and torsional vibrations, in which the interactions between the bridge deck, the TLCD, the aeroelastic forces, and
the aerodynamic forces are fully reflected. Both buffeting and flutter analyses are carried out. The buffeting analysis is
performed through random vibration approach, and a critical flutter condition is identified from flutter analysis. A numerical
example is presented to demonstrate the control effectiveness of the damper and it is shown that the TLCD can be an effective
device for suppressing wind-induced vibration of long span bridges, either for reducing the buffeting response or increasing
the critical flutter wind velocity of the bridge. 相似文献
9.
2021年5月21日云南漾濞发生6.4级地震,成为继2014年6.5级鲁甸地震和6.6级景谷地震之后云南省内时隔7年的又一次震级大于6级的破坏性地震。漾濞地震虽然与鲁甸地震在震级、震源深度和震源机制等方面均较相似,但漾濞地震震中附近的地面运动强度远不及鲁甸地震,且漾濞县的抗震设防烈度远高于鲁甸;相应地,漾濞地震对抗震设防建筑造成的破坏也远轻于后者。本文首先通过比较这三次地震震中附近的强震记录的反应谱,并结合公共建筑的震后应急评估结果,说明漾濞地震和鲁甸地震中公共建筑破坏程度的显著差异。进而以位于漾濞县城的两栋钢筋混凝土公共建筑为例,介绍此次地震中砌体填充墙和吊顶等典型非结构构件的震害。 相似文献
10.
《地震工程与结构动力学》2018,47(6):1566-1588
An experimental program was performed for evaluating the seismic response and fragilities of nonstructural lightweight steel drywall partitions, also considering the interaction with structural elements and other nonstructural building components, ie, outdoor façade walls. Therefore, in‐plane quasi‐static reversed cyclic tests were carried out on 8 specimens of indoor partition walls infilled in a frame and on 4 specimens of indoor partition walls connected at its ends with transversal outdoor façade walls. Constructive parameters under investigation include type of connections used for connecting the indoor partition walls to the surrounding elements, stud spacing, type of sheathing panels, and type of jointing finishing. The effect of the constructive parameters on the lateral response in secant stiffness and strength is examined. Furthermore, the main damage phenomena observed during the tests are reported and associated to 3 damage limit states distinguished for the required repair level for the tested partition walls. Fragility curves are used for the experimental assessment of seismic fragility of the tested specimens, in accordance with the interstorey drift limits required by the European code. Finally, the quantitative estimation of the repair action costs starting from the damage observation is also developed. The obtained results could be considered a starting point for developing the in‐plane seismic design assisted by testing of lightweight steel drywall partition walls. 相似文献
11.
《地震工程与工程振动(英文版)》2016,(2)
Severe damage to suspended ceilings of metal grids and lay-in panels was observed in public buildings during the 2013 Ms7.0 Lushan earthquake in China. Over the past several years, suspended ceilings have been widely used practice in public buildings throughout China, including government offices, schools and hospitals. To investigate the damage mechanism of suspended ceilings, a series of three-dimensional shake table tests was conducted to reproduce the observed damage. A full-scale reinforced concrete frame was constructed as the testing frame for the ceiling, which was single-story and infilled with brick masonry walls to represent the local construction of low-rise buildings. In general, the ceiling in the tests exhibited similar damage phenomena as the field observations, such as higher vulnerability of perimeter elements and extensive damage to the cross runners. However, it exhibited lower fragility in terms of peak ground/roof accelerations at the initiation of damage. Further investigations are needed to clarify the reasons for this behavior. 相似文献
12.
Response parameters used to estimate nonstructural damage differ depending on whether deformation‐sensitive or acceleration‐sensitive components are considered. In the latter case, seismic demand is usually represented through floor spectra, that is response spectra in terms of pseudo‐acceleration, which are calculated at the floor levels of the structure where the nonstructural components are attached to. Objective of this paper is to present a new spectrum‐to‐spectrum method for calculating floor acceleration spectra, which is able to explicitly account for epistemic uncertainties in the modal properties of the supporting structure. By using this method, effects on the spectra of possible variations from nominal values of the periods of vibration of the structure can be estimated. The method derives from the extension of closed‐form equations recently proposed by the authors to predict uniform hazard floor acceleration spectra. These equations are built to rigorously account for the input ground motion uncertainty, that is the record‐to‐record variability of the nonstructural response. In order to evaluate the proposed method, comparisons with exact spectra obtained from a standard probabilistic seismic demand analysis, as well as spectra calculated using the Eurocode 8 equation, are finally shown. Copyright © 2017 John Wiley & Sons, Ltd. 相似文献
13.
Yasushi Sanada Rokhyun Yoon Takumi Akahori Yuto Ojio Ho Choi Yousok Kim 《地震工程与结构动力学》2017,46(10):1645-1665
Nonstructural reinforced concrete flat walls architecturally designed as exterior/partition walls in concrete buildings were severely damaged by the 2011 earthquake off the Pacific coast of Tohoku. This damage was observed in the monolithic nonstructural flat walls of relatively old ductile concrete buildings. Although these flat walls might affect the overall seismic performance and behavior of a building, the nonstructural wall effects have not been clarified because of the complex interactions among the structural components. To understand these effects, this paper conducts an experimental and numerical investigation of the nonstructural wall effects, focusing on a typical residential building damaged by the 2011 earthquake. A single‐story, one‐bay moment‐resisting frame model of the building with a nonstructural flat wall was tested to clarify the fundamental behavior. The results reveal that the wall significantly contributed to the seismic performance of the overall frame until it failed in shear, subsequently losing structural effectiveness. Such experimental wall behavior could be simulated by the isoparametric element model. Moreover, the structural effects of the nonstructural flat walls on the global seismic performance and behavior of the investigated building were discussed through earthquake response analyses using ground motions recorded near the building site and pushover analyses. Consequently, the building damage could be simulated in an analytical case considering the nonstructural flat walls, showing larger inter‐story drifts in the lower stories due to softening of the walls. The analytical results also indicated that the softening of the nonstructural flat walls decreased the building ductility, as defined by ultimate inter‐story drifts. Copyright © 2017 John Wiley & Sons, Ltd. 相似文献
14.
Severe damage to suspended ceilings of metal grids and lay-in panels was observed in public buildings during the 2013 M s7.0 Lushan earthquake in China. Over the past several years, suspended ceilings have been widely used practice in public buildings throughout China, including government offices, schools and hospitals. To investigate the damage mechanism of suspended ceilings, a series of three-dimensional shake table tests was conducted to reproduce the observed damage. A full-scale reinforced concrete frame was constructed as the testing frame for the ceiling, which was single-story and infilled with brick masonry walls to represent the local construction of low-rise buildings. In general, the ceiling in the tests exhibited similar damage phenomena as the field observations, such as higher vulnerability of perimeter elements and extensive damage to the cross runners. However, it exhibited lower fragility in terms of peak ground/roof accelerations at the initiation of damage. Further investigations are needed to clarify the reasons for this behavior. 相似文献
15.
A suite of reinforced‐concrete frame buildings located on hill sides, with 2 different structural configurations, viz step‐back and split‐foundation, are analyzed to study their floor response. Both step‐back and split‐foundation structural configurations lead to torsional effects in the direction across the slope due to the presence of shorter columns on the uphill side. Peak floor acceleration and floor response spectra are obtained at each storey's center of rigidity and at both its stiff and flexible edges. As reported in previous studies as well, it is observed that the floor response spectra are better correlated with the ground response spectrum. Therefore, the floor spectral amplification functions are obtained as the ratio of spectral ordinates at different floor levels to the one at the ground level. Peaks are observed in the spectral amplification functions corresponding to the first 2 modes in the upper portion of the hill‐side buildings, whereas a single peak corresponding to a specific kth mode of vibration is observed on the floors below the uppermost foundation level. Based on the numerical study for the step‐back and split‐foundation hill‐side buildings, simple floor spectral amplification functions are proposed and validated. The proposed spectral amplification functions take into account both the buildings' plan and elevation irregularities and can be used for seismic design of acceleration‐sensitive nonstructural components, given that the supporting structure's dynamic characteristics, torsional rotation, ground‐motion response spectrum, and location of the nonstructural components within the supporting structure are known, because current code models are actually not applicable to hill‐side buildings. 相似文献
16.
Sachi Furukawa Eiji Sato Yundong Shi Tracy Becker Masayoshi Nakashima 《地震工程与结构动力学》2013,42(13):1931-1949
Base isolation is a well known technology that has been proven to reduce structural response to horizontal ground accelerations. However, vertical response still remains a topic of concern for base‐isolated buildings, perhaps more so than in fixed‐base buildings as isolation is often used when high performance is required. To investigate the effects of vertical response on building contents and nonstructural components, a series of full‐scale shaking table tests were conducted at the E‐Defense facility in Japan. A four‐story base‐isolated reinforced concrete building was outfitted as a medical facility with a wide variety of contents, and the behavior of the contents was observed. The rubber base isolation system was found to significantly amplify vertical accelerations in some cases. However, the damage caused by the vertical ground motions was not detrimental when peak vertical floor accelerations remained below 2 g with three exceptions: (1) small items placed on shelves slid or toppled; (2) objects jumped when placed on nonrigid furniture, which tended to increase the response; and (3) equipment with vertical eccentricities rocked and jumped. In these tests, all equipment and nonstructural components remained functional after shaking. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
17.
Seismic demand on light acceleration‐sensitive nonstructural components in European reinforced concrete buildings 
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下载免费PDF全文 In this paper, a parametric study is conducted in order to evaluate the seismic demand on light acceleration‐sensitive nonstructural components caused by frequent earthquakes. The study is motivated by the inconsistent approach of current building codes to the design of nonstructural components; the extensive nonstructural damage recorded after recent low‐intensity earthquakes also encouraged such a study. A set of reinforced concrete frame structures with different number of stories, that is, 1 to 10 stories, are selected and designed according to Eurocode 8. The structures are subjected to a set of frequent earthquakes, that is, 63% probability of exceedance in 50 years. Dynamic nonlinear analyses are performed on the reference structures in order to assess the accuracy of the equations to predict seismic forces acting on nonstructural components and systems in Eurocode. It is concluded that the Eurocode equations underestimate the acceleration demand on nonstructural components for a wide range of periods, especially in the vicinity of the higher mode periods of vibration of the reference structures; for periods sufficiently larger than the fundamental period of the structure, instead, the Eurocode formulation gives a good approximation of the floor spectra. Finally, a novel formulation is proposed for an easy implementation in future building codes based on the actual Eurocode provisions. The proposed formulation gives a good estimation of the floor spectral accelerations and is able to envelope the floor spectral peaks owing to the higher modes. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
18.
考虑地铁环境振动噪声对未来城市地铁地震警报系统中地震信号识别的影响,以包含Ⅱ类和Ⅲ类2种场地土类型的哈尔滨市4个地铁站的上行线首部和尾部作为观测点,展开地铁环境振动噪声的测试、分析以及降噪处理研究。首先,对采集的列车振动数据进行统计分析;其次,基于滑动平均法,提出确定帕曾窗带宽b值的经验方法,并利用其对采集的地脉动数据进行平滑滤波处理;最后,采用本方法确定哈尔滨地铁地震P波预警的滤波频带,并与日本气象厅仪器地震烈度以及新干线地震预警系统的滤波频带进行对比。结果表明:①三轴向地铁列车振动信号中,竖向振动比水平向振动要大,切向振动比径向振动要大。②帕曾窗带宽b值为0.4 Hz时,平滑滤波处理后的频谱能较好地反映地脉动信号的频谱主频,且滤波后的地脉动信号的卓越频率和场地土类型有明显的对应关系,即水平向卓越频率和场地土类型的相关性较好,而竖向卓越频率的误差较大。③哈尔滨地铁地震P波预警的滤波频带为0.3~10 Hz时,能较好地滤除地震动信号中的地铁环境振动噪声,满足地震警报系统对地震记录信噪比的要求。 相似文献
19.
<正>Recently,the high-tech industry has become a key industry for economic development in many countries. However,vibration sensitive equipment located in these industrial buildings is vulnerable during earthquakes,which may cause huge economic loss.In this study,an innovative isolator for safeguarding the vibration sensitive equipment,namely, the static dynamics interchangeable-ball pendulum system(SDI-BPS) is proposed and investigated to examine its protective capability for the vibration sensitive equipment during earthquakes through a series of tri-directional shaking table tests.The experimental results illustrate that the SDI-BPS isolator can provide significant damping to rolling types of base isolation systems for reducing the bearing displacement and size,and avoid the stress concentration,which can cause damage or scratches on the rolling surface of the isolator,to prolong its life span of service.The SDI-BPS isolator also provides excellent capability in protecting the vibration sensitive equipment and exhibits a stable behavior under long terms of service loadings and earthquakes. 相似文献
20.
基于建筑性能的非结构构件抗震设计研究 总被引：2，自引：0，他引：2
针对非结构构件在地震中破坏的现象、震害情况,分析破坏原因,给出了非结构构件的抗震设防目标。基于建筑物性能的基本思想,给出了非结构构件的性能设计要求;讨论了非结构构件和附属设备的抗震设计计算原则。对建筑的非结构构件提出了相应的抗震设防技术措施,以提高其抗震能力。 相似文献