Research and application on three-dimensional seismic and vibration isolation for building

This paper presents the study of a three-dimensional(3D) isolation system.Firstly,the authors investigated the effects of an innovative 3D isolator,which was composed of a connecting plate,a rubber pad for vibration isolation in the vertical direction and a horizontal rubber bearing for seismic isolation in both horizontal directions.Secondly,the authors designed such a vibration isolation system and installed it underneath two specific residential buildings which were built directly over an existing subway communication hub platform in Beijing.These buildings required good performance vibration and seismic isolation system to reduce the impact from the running of nearby subway trains.Finally,in situ tests were conducted for both the isolated and the non-isolated buildings for the purpose of comparison.The test results showed that the maximum acceleration response level of the isolated superstructure is reduced by 10% as compared to that of the platform.The maximum attenuation of vibration reaches up to 25 dB.The 3D system explored in this paper is very effective in control and suppression of building vibration induced by earthquakes or running of trains.

Three-dimensional seismic isolation bearing and its application in long span hangars

Based on the seismic response characteristics of space frame structures,a new type of seismic isolation bearing defined as a three-dimensional seismic isolation bearing（3DSIB） is developed in this paper.The bearing offers excellent properties such as multi-dimensional seismic isolation,reasonable rotation capability,good ability to resist lifting load,uncoupled stiffness in horizontal and vertical directions,etc.In the 3DSIB,the horizontal dimension is designed by combining the Teflon sliding device and helical spring,while the vertical dimension is developed by introducing disk springs or helical springs.The mathematical model of the 3DSIB was established and its performance with the critical parameters was tested on a shaking table.Furthermore,the 3DSIB was applied in a 120 m span hangar structure and simulated using SAP2000 software to evaluate its performance in practical structures.The performance of the structures with and without 3DSIB was compared.It is shown that the hangar structure with 3D bearings achieves a better performance.The axial force and acceleration response of the structures with 3DSIB are effectively reduced,while the displacement response of the bearing is within the predetermined range.

INFLUENCE OF DAMPING MODELS ON DYNAMIC ANALYSES OF A BASE-ISOLATED COMPOSITE STRUCTURE UNDER EARTHQUAKES AND ENVIRONMENTAL VIBRATIONS

Structural design simultaneously governed by earthquakes and environmental vibrations has received a lot of attention in recent years.Base-isolated composite structures are typically used in the above-mentioned structural design.The corresponding analysis involves validating structural safety under earthquakes and human comfort under environmental vibrations through a time-history analysis.Thus,a reasonable damping model is essential.In this work,the representatives of viscous damping model and rate-independent damping model,namely the Rayleigh damping model and uniform damping model,were adopted to investigate the influence of damping models on the time-history analysis of such structural designs.The energy dissipation characteristics of the above-mentioned damping models were illustrated via a dynamic test of recycled aggregate concrete specimens.A case study was performed on a base-isolated steelconcrete composite structure.The dynamic responses under the excitation of earthquakes and environmental vibrations were compared using different damping models.The uniform damping model was found to be more flexible than the Rayleigh damping model in dealing with excitations with different frequency components.The uniform damping model is both theoretically advantageous and easy to use,demonstrating its potential in dynamic analysis of structures designed simultaneously governed by earthquakes and environmental vibrations.

Simplified Method and Influence Factors of Vibration Characteristics of Isolated Curved Girder Bridge

The isolated curved girder bridge's vibration characteristics play a major part in the seismic responses of structures and anti-seismic properties.A clear analytic relationship between design parameters and the system's vibration characteristics could be established by its simplified dynamic analysis model,making it convenient for providing a reference to the optimization of design and safety analysis.A double-mass six-degree-of-freedom model for curved girder bridges with isolation bearings installed at the top of the bridge piers is built and a simplified analysis method for the vibration characteristics of the system is provided.Combined with the Matlab programming,the influences of radius of curvature,central angle,bridge deck width and damping ratio of the isolation layer and circular frequency of the isolation layer of isolated curved girder bridges on the pseudo-undamped natural circular frequency(called pseudo-frequency for short)and system damping ratio are systematically analyzed,and the sensitivity of vibration characteristics of isolated curved girder bridges is studied.The results show that the vibration characteristics of isolated curved girder bridges can be reflected well with this simplified model and calculation method.The pseudo-frequency of curved girder and system damping ratios increases with the increase of the isolation layer.The third-order vibration characteristic is more sensitive to the parameters of a curved girder,and the first-order vibration characteristic is sensitive to both central angle and radius of curvature to some extent while insensitive to the width of the bridge deck.Furthermore,the second-order vibration characteristic is not sensitive to the parameters of a curved girder.

Optimal design and effectiveness evaluation for inerter-based devices on mitigating seismic responses of base isolated structures

The optimal design and effectiveness of three control systems,tuned viscous mass damper(TVMD),tuned inerter damper(TID)and tuned mass damper(TMD),on mitigating the seismic responses of base isolated structures,were systematically studied.First,the seismic responses of the base isolated structure with each control system under white noise excitation were obtained.Then,the structural parameter optimizations of the TVMD,TID and TMD were conducted by using three different objectives.The results show that the three control systems were all effective in minimizing the root mean square value of seismic responses,including the base shear of the BIS,the absolute acceleration of structural SDOF,and the relative displacement between the base isolation floor and the foundation.Finally,considering the superstructure as a structural MDOF,a series of time history analyses were performed to investigate the effectiveness and activation sensitivity of the three control systems under far field and near fault seismic excitations.The results show that the effectiveness of TID and TMD with optimized parameters on mitigating the seismic responses of base isolated structures increased as the mass ratio increases,and the effectiveness of TID was always better than TMD with the same mass ratio.The TVMD with a lower mass ratio was more efficient in reducing the seismic response than the TID and TMD.Furthermore,the TVMD,when compared with TMD and TID,had better activation sensitivity and a smaller stroke.

Dynamic performance analysis of a seismically isolated bridge under braking force

In order to study the dynamic performance of seismically isolated bridges under the most unfavorable loads in the longitudinal direction, a dynamic equation for vehicle braking in the longitudinal direction is established. A four or five- order Runge-Kutta method is adopted to obtain the time-history response of a wheel set under braking force. The quadratic discretization method is then used to transform this time-history into a braking and bending force time-history of a structural fixed node, and a dynamic response analysis of the seismically isolated bridge under the vehicle＇s braking force is carried out using ANSYS, a universal finite element analysis software. According to the results, seismic isolation design results in a more rational distribution of braking force among piers; the influence of the initial braking velocity on the vehicle braking force is negligible; the location where the first wheel set leaves the bridge is the most unfavorable parking location; a seismic isolation bridge bearing constructed according to typical design methods enters into a yield stage under the braking force, while the shearing force at the bottom of the pier declines as the isolation period is extended; the design requirements can be met when the yield displacement of the seismic isolation bearing is less than 5 mm and the yield strength is greater than the braking force.

近远场地震下RC大跨轻柔拱桥减隔震支座方案优化

为探明不同地震动输入对某大跨轻柔拱桥减隔震的影响,通过非线性有限元模型分析近远场地震下桥梁结构的响应规律,得到大桥支座的优化布置方案.首先,基于模态分析,对比该桥与传统钢筋混凝土(RC)拱桥动力特性差异;其次,选取不同脉冲周期的近场地震动、近场无脉冲及远场长周期地震动记录;最后,研究近远场地震下拱桥的响应行为和损伤演化路径,得到优化桥梁的减隔震支座设计方案.研究结果表明:近场脉冲及远场长周期地震下的桥梁结构响应大于无脉冲地震响应;纵竖向地震下高墩柱剪力及弯矩包络曲线呈“S”形,墩身中部易形成塑性铰,高阶振型影响显著;桥梁纵桥向先于横向震损,损伤路径依次为矮柱、高墩柱及拱肋实心-空心截面段;摩擦摆支座减震效果最佳但位移较大,高阻尼支座方案在近场中长脉冲周期及远场长周期地震下仍会发生损伤,板式橡胶支座方案因无法保证支座同步滑移而不能形成准隔震体系;“高阻尼+摩擦摆”混合方案的支座位移小,拱肋及墩柱均处于弹性,是近断层大跨轻柔RC拱桥的优选减隔震方案.

巨型框架三维隔震结构风振响应分析

以日本NEC办公大楼的结构方案为例,采用SAP2000建立巨型框架抗震结构和巨型框架三维隔震结构的分析模型,对结构施加脉动风荷载,分析子框架调谐比和隔震层阻尼比对巨型框架三维隔震结构减振效果的影响规律,进而完成参数优化,最后对两种结构的位移和加速度进行风振响应分析。研究结果表明:子框架调谐比和隔震层阻尼比分别设置为0.53和0.3时,可使巨型框架三维隔震结构减振效果达到最佳;在脉动风荷载作用下,三维隔震支座的设置能够同时对主、子框架的风振响应实现有效控制。

Optimal design for rubber concrete layered periodic foundations based on the analytical approximations of band gaps and mapping relations

The seismic performance of rubber concrete-layered periodic foundations are significantly influenced by their design,in which the band gaps play a paramount role.Aiming at providing better designs for these foundations,this study first proposes and validates the analytical formulas to approximate the bounds of the first few band gaps.In addition,the mapping relations linking the frequencies of different band gaps are presented.Furthermore,an optimal design method for these foundations is developed,which is validated through an engineering example.It is demonstrated that ensuring the superstructure’s resonance zones are completely covered by the corresponding periodic foundation’s band gaps can achieve satisfactory vibration attenuation effects,which is a good strategy for the design of rubber concrete layered periodic foundations.

大型交通枢纽结构振动传播规律及隔振/震措施

[目的]大型综合交通枢纽结构作为城市布局的重要组成,具有投资巨大、建设规模庞大、使用功能繁杂等特点。保证此类建筑物在地震作用下免遭破坏或损伤同时保留其使用功能,以及在多重立体交通作用下使其具有足够的安全性和舒适性是具有实际意义的工程问题,因此需对相关文献研究进行整理和归纳总结。[方法]综述了各类交通荷载引起的沿线地面和建筑物等的环境振动问题,以及交通枢纽结构常采用的减隔振/震装置的研究现状;总结了现阶段国内外学者在振动响应实测、振动预测模拟和振动传播规律方面的研究成果;基于现有研究的局限性,阐述了在交通枢纽结构环境振动控制方面的未来研究方向。[结果及结论]国内外对于三维复合隔振/震的研究相对较少,研究主要集中于轨道交通沿线或上盖建筑物的地铁振动隔振,且主要集中在对所提隔振/震装置的力学性能和减隔振/震效应的试验研究。目前,对三维复合隔振/震的理论及技术研究还不够深入,三维复合隔振/震的应用还未普及并形成相关体系,相关装置的研发及其减振机理、力学性能、理论模型等仍是亟待解决的关键问题。

高层隔震结构减震机理和设计分析

随着《建筑抗震管理条例》的颁布,隔震建筑在工程建设中的应用将越来越广泛。以福州某办公楼隔震结构设计为研究对象,采用有限元软件YJK和ETABS分析了主要振型的反应谱。给出了抗震设计目标确定的方法、地震波的选取方法和减震机理,得出了可供工程技术人员借鉴的主要结论:地震波选取时可通过观察地震波的时程曲线图的主要周期点和最大加速度值并对比反应谱与规范谱的拟合度,来判断其与建筑场地是否相适应;高层结构在底部设置隔震支座能够显著改善上部结构的地震反应谱,其减震机理并不是延迟周期而是滤波原理。

深海建筑施工中的振动隔离和抗震措施研究

文章通过分析深海环境对建筑结构的影响,探讨了深海建筑的自然振动频率和深海建筑受外力激励振动响应的特性。针对深海建筑施工中存在的振动问题,研究了主动、被动和半主动振动控制技术,且分析了深海建筑抗震加固技术、地震响应评价技术和抗震监测与预警系统等抗震措施。研究结果表明,在深海建筑施工中,采用适当的振动隔离和抗震措施可以有效地降低建筑的振动响应,提高建筑的抗震能力和安全性。

公轨合建大跨长联桥梁减隔震设计关键技术研究

文中从公轨合建大跨长联桥梁结构特点出发,推荐采用具有双向隔震功能的位移型减隔震支座方案,尤以高承载力的双曲面摩擦摆减隔震支座最合适。通过对双曲面摩擦摆减隔震支座参数分析,提出采用上限和下限不同隔震状态确定控制区域范围进行减隔震设计。同时对于采用双曲面球型摩擦摆减隔震支座的公轨合建桥梁,需要考虑支座附加变形影响,开展车桥耦合振动分析,减隔震支座附加变形对车辆竖向加速度指标影响较大,应重点关注。

桥梁抗震设计要点及减隔震技术的应用分析

桥梁抗震设计是一项重要的工程任务,涉及到结构的稳定性和安全性。在设计过程中,需要充分考虑地质条件、结构材料、支座类型等因素,减隔震技术作为提高桥梁抗震性能的有效手段之一,可以通过降低地震作用对桥梁的影响,减少结构受力,从而保障桥梁在地震中的安全性。文章结合当前桥梁抗震设计中存在的主要问题,分析了桥梁抗震设计要点以及减隔震技术的有效应用策略,以不断提高桥梁工程质量。

Describe the Process of Retrofitting Existing Buildings and Evaluate the Effectiveness of it in Improving the Seismic Performance of Structures in Earthquake-prone Regions

At present,earthquakes are a serious problem for building.Severe damages and collapses of buildings were caused by earthquakes in different degrees.It is reported that there are more than 68,858 deaths and hundreds of billions RMB losses in the May 12,2008 Great Wenchuan Earthquake[16].So,more attention should be paid to seismic technology.In order to face the challenges of earthquake on building,the seismic retrofitting was put forward,which“is the modification of existing structures to make them more resistant to seismic activity,ground motion,or soil failure due to earthquakes”[2].

土工袋隔震农村民居现场激振测试及效果评价

为验证土工袋垫层在城乡中低层民居中的减隔震效果,在地震多发区金沙江白鹤滩水电站坝址附近的民居点修建了中国首幢含有土工袋隔震垫层的农村民居。土工袋隔震垫层主要由土工编织袋包裹建筑级配砂堆叠而成,具有就地取材,价格低廉、施工简单等技术优势,适用于广大农村地区的中低层房屋建筑。现场大型原位激振试验结果表明:经过土工袋垫层处理后,地基结构三向峰值加速度的绝对值和隔震系数较未处理时均显著减小,验证了原位条件下土工袋垫层房屋基础具有良好的隔震效果,有望在实际地震来临之时保障民居免遭严重损失,为城乡综合隔震减灾提供新技术思路。

某百米级高层隔震结构风致效应研究

现行规范采用静力设计的方法可能对高层隔震结构的风致效应考虑不足,为此深入研究了高层隔震结构抗风设计与风致效应,结合现行规范提出高层隔震结构风致效应分析框架,并针对中国某百米级实际工程隔震结构展开风致效应的分析与评估。结果表明:现行规范采用等效静力的计算方式低估了高层隔震结构实际所受的脉动风作用,通过风荷载时程分析发现,隔震层X、Y向的水平剪力相比风荷载标准值作用分别增加了23.8%和27.7%,但从设计的角度出发,现行规范取1.4的分项系数能满足隔震层抗风稳定性的要求;在10年一遇风荷载作用下,高层隔震结构顶部存在舒适度的问题,最大风振加速度达到16.2 cm·m^(-2),超出规范限值8%;在1年一遇风荷载作用下,高层隔震结构顶部的最大风振加速度达到7.6 cm·m^(-2),其居住舒适性更难以满足,高层隔震结构的舒适度问题在今后的抗风设计中应予以重视;提出的分析框架能较系统和全面地反映高层隔震结构风致效应,可为现行规范提供理论参考依据。

基于离散单元法碎石垫层隔震性能的宏细观分析

为研究非接触桩箱复合基础中碎石垫层隔震性能,采用颗粒流软件PFC^(3D)对碎石垫层和沉箱进行模拟分析,从宏细观多角度对碎石垫层隔震性能进行分析。研究结果表明,竖向压力、垫层厚度对垫层隔震效果的影响较大;地震动加载过程中,垫层底部颗粒水平相对位移较大,垫层中上部颗粒水平相对位移较小,颗粒配位数及垫层孔隙率与碎石垫层隔震效果关系密切。

地震作用下附建式变电站电气设备动力响应

附建式变电站通常会对电气设备采取隔振措施以减小设备振动及噪声通过结构传播扰民。然而,目前常用的隔振装置系统的自振频率通常位于2~10 Hz之间,与地震动卓越频率相近。因此,这类隔振装置在地震发生时,往往无法发挥隔震效果,反而可能会放大地震的作用,导致采用了隔振措施的电气设备更容易受到损坏。通过有限元模拟的方法,旨在研究不同周期类型的地震动激励下,采用常规隔振方案的电气设备的动力响应。结果表明,采用普通隔振装置后,电气设备所受的竖向地震作用响应相较楼板处有不同程度的放大。这一发现对电气设备的抗震设计提出了重要的警示,需要更加谨慎地考虑隔振装置的选用,以确保设备在地震发生时能够有效地减小振动,降低损坏风险。

负刚度-惯容阻尼器对隔震结构减震性能提升研究

为进一步控制地震作用下基础隔震结构的地震响应,融合负刚度与惯容的减震优势,开展了负刚度-惯容阻尼器(Negative Stiffness Inerter Damper,NSID)对隔震结构减震性能提升研究。基于NSID-隔震结构耦合系统的状态空间方程,推导了Clough-Penzien谱输入下耦合系统随机地震响应;综合NSID设计成本和隔震结构减震性能提升需求,提出了基于成本控制的NSID参数优化方法;通过对比NSID、黏滞阻尼器(Viscous Damper,VD)、负刚度阻尼器(Negative Stiffness Damper,NSD)、惯容阻尼器(Viscous Inerter Damper,VID)对隔震结构在近场脉冲型地震作用下的控制效果,阐明了NSID对隔震结构减震控制的优势。研究结果表明:基础隔震复合NSID的减震措施可以有效降低隔震结构的隔震层位移,以及上部结构层间位移和绝对加速度响应;由于负刚度元件的存在,NSID对隔震结构位移的控制效果稍劣于VID,但优于NSD和VD;优化设计的NSID综合了惯容和负刚度对隔震结构层间位移和绝对加速度的控制优势,对隔震结构层间位移和绝对加速度的控制效果优于VD、VID和NSD。