隔震结构动力分析与优化

经过多次地震证明隔震结构能够极大的降低地震作用,工程界对隔震结构研究越来越多,但主要集中在隔震支座新形式及高层隔震应用上,而对多层常规隔震设计问题关注较少。文中通过对一则多层隔震框架结构的分析发现:多层结构支座型号选用主要由大震隔震层位移确定;当支座拉力较大时,建议优先采用调整地上柱网或隔震层转换等常规设计手段避免或降低支座拉力,常规设计手段无法解决时再采用抗拉装置或其他高抗拉支座。     

摩擦摆隔震结构振动台模型设计方法研究北大核心

随着隔震技术的应用发展,摩擦摆支座作为一种新颖的隔震支座,已逐步在国内外工程中使用。摩擦摆隔震结构的振动台试验模型设计方法具有特殊性,对其特殊性的把握将直接影响振动台试验的结果。以西昌(9度区)某基础隔震高层框架-核心筒结构为原型结构,研究了摩擦摆隔震结构的振动台试验模型设计的核心方法,包括模型整体相似关系、隔震支座数量等效、隔震层相似关系、隔震层等效以及模型支座参数确定,以期为今后摩擦摆隔震结构振动台试验模型设计提供参考。     

橡胶隔震支座应用于村镇低矮砌体结构的抗震性能及构造设计

针对橡胶隔震支座在村镇低矮砌体结构中未被广泛应用的现状,设计一种新的安放橡胶隔震支座的方法。对比分析了采用该设计与采用传统隔震设计的上部结构的抗震性能及空间整体性,给出了隔震支座的布置原则和安放方法,设计了门洞口、室内外楼梯、管线等特殊部位的构造处理方案,提出了安装橡胶隔震支座的具体施工工艺及应注意的问题。结果表明:该设计方法用于低矮房屋中,造价低廉、施工工艺简单且隔震效果好;所提出的隔震设计可应用于村镇低矮砌体结构建筑。     

奎山小区住宅楼并联基础隔震结构设计研究

并联基础隔震结构是由橡胶隔震支座与摩擦滑移隔震支座并联组合形成的隔震结构,两种型式的隔震支座相互取长补短,可有效降低隔震结构的造价,文中介绍该结构形式在某住宅楼工程中的设计应用,。     

低矮砌体结构橡胶隔震支座力学性能研究

数量众多又缺乏抗震措施的村镇民居已成为我国抗震设防的薄弱环节,为解决这一问题,将日趋成熟的橡胶支座隔震技术应用到村镇低矮砌体结构民居中,分析其力学性能和设计方法。针对低矮砌体结构的特点,设计3种规格的橡胶隔震支座,通过拟动力试验研究隔震层在模拟地震作用下的破坏过程和滞回曲线,得到隔震层和支座的等效水平刚度、屈服后刚度、阻尼比等力学性能,分析其在不同强度地震作用下力学性能的变化,并对比支座的力学参数测定值。验证了按照底部剪力法对低矮砌体结构隔震支座进行设计的合理性,得到了适用于村镇低矮砌体结构的隔震支座的力学性能参数,提出了该类支座在地震作用下的破坏机理,并为制订村镇砌体结构隔震技术方面的相关规程提供试验数据和力学分析方法。     

水平双向地震作用对摩擦摆基础隔震结构隔震支座位移的影响

对不同场地条件下、不同周期的摩擦摆基础隔震结构在水平双向和单向地震作用下的隔震支座位移进行了对比分析,表明水平双向地震作用下隔震支座的总位移均明显大于水平单向地震作用下的支座位移。因而,在简化设计中确定摩擦摆基础隔震结构隔震支座位移时,可将水平单向地震作用下的隔震支座位移增大30%,以考虑水平双向地震作用对摩擦摆基础隔震结构隔震支座位移的影响。     

9度区高层隔震结构设计与分析方法

隔震结构所采用的材料与传统抗震结构有很大的不同,设计方法也有差异。以抗震了设防烈度为9度区的某小区高层隔震结构为例,重点介绍了规范对隔震计算分析的相关要求、竖向地震作用计算、支座计算模型选择、支座拉应力分析等内容。分析结果表明,对于支座参数设计合理、各项指标均能满足规范要求的高烈度地区高层隔震结构,上部结构地震响应明显降低,抗震性能也得到很大提高。     

水平双向地震作用下基础隔震结构支座位移的确定

对不同场地条件下,不同周期的基础隔震结构在水平双向和单向地震作用下的隔震支座位移进行了对比分析,表明水平双向地震作用下隔震支座的总位移均明显大于水平单向地震作用下的支座位移,其比值的平均值为1.187,因而,在简化设计中确定基础隔震结构隔震支座位移时,可将水平单向地震作用下的隔震支座位移增大20%,以考虑水平双向地震作用对基础隔震结构隔震支座位移的影响。     

沿海地区隔震结构减震与抗风优化设计

沿海风载较大地区部分隔震结构的设计无法同时满足减震目标与隔震层抗风要求，为此设计了专用的抗风支座。以某实际工程为背景，建立多种不同隔震层布置下的结构计算模型并进行时程分析，对隔震结构的减震与抗风进行优化设计，最后通过有限元静力加载分析验证了抗风支座的有效性。计算结果表明：通过合理选择铅芯支座和抗风支座的数量并进行优化布置，可以解决沿海风载较大地区隔震结构减震效果与抗风设计难以协调的问题；建议设计时铅芯支座提供的水平承载力接近风载下隔震层的水平剪力标准值；抗风支座能满足设计要求，即风载和小震下参与隔震层工作，中震破坏退出工作。     

核电厂隔震结构动力分析

基于铅芯橡胶支座,以某核电站核岛厂房为例,进行基础隔震技术在核电站结构设计中的应用研究,包括整体隔震方案的设计、隔震装置的选择、计算模型的确定等,并通过动力时程分析对比研究隔震支座布置间距和隔震层恢复力模型对结构加速度和位移响应的影响。研究结果表明:采用隔震措施后,结构自振周期明显增大,上部结构加速度响应明显减小,同时整体位移也会增加较多,但层间位移很小;相比隔震支座等效线性模型,双线性模型更符合支座的实际滞回特性,在实际设计中应优先考虑采用。     

宿迁市府苑小区综合楼隔震分析

宿迁市府苑小区综合楼位于 8度区 ,设计基本地震加速度值为 0 3 0 g ,为 6层底部框架砌体结构 ,平面呈三折线形。工程采用基础隔震技术进行结构设计 ,隔震层由橡胶隔震支座、滑移支座、粘滞消能器组成。对隔震体系空间模型的时程分析表明 :采用基础隔震措施可显著降低上部结构的地震作用 ;设置粘滞消能器能较好地解决降低上部结构的地震作用和限制隔震层位移之间的矛盾 ,有效地消除结构的扭转效应     

Seismic isolation design of the San Bernardino County Medical Center replacement project

The San Bernardino County Medical Center Replacement Project, located in Colton, California, consists of six separate building structures containing a total of approximately 920 000 ft² of floor space for hospital and support services. Five of the six buildings will be base isolated. Each of the five base isolated buildings is of different size and configuration, ranging from a six story, 360 000 ft² curved front Nursing Tower to a two story, 24 000 ft² rectangular shaped Central Plant building. The building structures will be framed with structural steel, utilizing concentric braced frames as the lateral force resisting system. The design ground motion for the site, which is located 3 km and 15 km from the San Jacinto and San Andreas faults respectively, is very severe. A base isolation system has been designed for this facility which will provide an essentially elastic building response to the design strong ground motion. The base isolation system is a hybrid passive energy dissipation system consisting of both linear and nonlinear and high damping rubber bearings along with viscous damping devices located at the base of the structure. The high damping rubber bearings provide both lateral stiffness which governs the fundamental period of vibration of the system, and hysteretic damping, while the viscous damping devices provide velocity dependent damping which serves to control overall building displacements. This will maximize the probability that this essential facility will remain fully operational after a major earthquake. Design criteria, structural analysis and design methodologies, and construction details are presented and discussed. The response of one of the base isolated structures is calculated utilizing actual recorded ground motions from the 1994 Northridge earthquake.     

Robustness of base‐isolated high‐rise buildings under code‐specified ground motions

The robustness of base‐isolated high‐rise buildings is investigated under code‐specified ground motions. Friction‐type bearings are often used in base‐isolated high‐rise buildings to make the natural period of those buildings much longer. While additional damping can be incorporated into every story in passive controlled structures with inter‐story type passive members, that can be incorporated into the base‐isolation story only in the base‐isolated building. This fact leads to the property that, as the number of stories of the building becomes larger, the damping ratio reduces. This characteristic may cause some issues in the evaluation of robustness of base‐isolated high‐rise buildings. The purpose of this paper is to reveal the robustness of base‐isolated high‐rise buildings. A kind of inverse problem for the target drift in the base‐isolation story is formulated in order to determine the required quantity of additional viscous damping. It is demonstrated numerically that, as the base‐isolated building becomes taller, the damping ratio becomes smaller and the ratio of the friction‐type bearings in the total damping becomes larger. This may lead to the conclusion that base‐isolated high‐rise buildings have smaller robustness than base‐isolated low‐rise buildings. Copyright © 2007 John Wiley & Sons, Ltd.     

Seismic response of base isolating systems with U-shaped hysteretic dampers

This paper proposes a base isolating system to reduce the seismic demands of low- or medium-rise structures and experimentally investigates its seismic response using shake-table tests. The base isolating system considered in this study consists of laminated-rubber bearings and U-shaped hysteretic (UH) dampers which are made of high toughness steel (HTS) and are machined with slotted holes to increase their deformation capacities. A base isolated 2-story specimen for shake-table tests was first designed and cyclic tests of laminated-rubber bearings and UH dampers implemented in the base isolating systems were then carried out. The component test for the laminated-rubber bearings shows typically low lateral stiffness with enough vertical stiffness to carry gravity loads. The test results for the UH dampers demonstrate that the use of HTS material and the introduction of the slotted holes details increase deformation capacities by inducing uniform stress distribution along a UH damper. Finally, shake-table tests were performed using specimens shaken with increasing ground acceleration records. The shake-table tests show that the proposed base isolating system with UH dampers limits the seismic demands of a base isolated structure by lengthening its structural period, concentrating displacement demands on the base isolating floor and adding seismic energy dissipation from the UH dampers.     

Los Angeles City Hall

This paper describes the Los Angeles City Hall building and a unique seismic strengthening program. Four hundred and sixteen high damping rubber bearings, 90 flat sliding bearings and 64 viscous dampers have been installed as part of the seismic rehabilitation. The building is a 460 feet tall steel frame with unreinforced masonry infill. The rehabilitation consists of installing high damping rubber bearings at its base supplemented with nonlinear viscous dampers. This paper describes various aspects of the project including the development of seismic performance goals, identification of inherent seismic deficiencies of the existing building, evaluation of alternative strengthening schemes, the final design process and construction issues. Copyright © 2000 John Wiley & Sons, Ltd.     

宿迁市人防指挥大楼隔震设计方法研究

宿迁市人防指挥大楼位于地震高烈度区,钢筋混凝土框架-剪力墙结构,地上13层,高48.9m。该工程采用基础隔 震技术设计,为我国目前最高的隔震建筑之一。隔震层布置在地下室顶板和±0.00楼面之间,由橡胶隔震支座、滑移支座 和粘滞阻尼器组成,共采用了53只橡胶隔震支座、12只滑移支座,沿结构的两个主轴方向共设置4只非线性粘滞阻尼 器。分析结果表明,采用基础隔震措施可显著降低上部结构的地震作用;设置粘滞消能器能较好地解决降低上部结构地震 作用和限制隔震层位移之间的矛盾。在本工程中采用基础隔震技术,具有明显的技术经济效益。     

Resonant behaviour of base‐isolated high‐rise buildings under long‐period ground motions

The resonant behaviour of base‐isolated high‐rise buildings under long‐period ground motions is investigated. The long‐period ground motions are known to be induced by surface waves. While the acceleration amplitude of such long‐period ground motion is small, the velocity amplitude is fairly large. It is expected that high‐rise buildings and base‐isolated buildings with long fundamental natural periods are greatly influenced by these long‐period ground motions. Especially base‐isolated high‐rise buildings with friction‐type bearings may have remarkable mechanical characteristics unfavourable for these long‐period ground motions. The purpose of this paper is to reveal that the long‐period ground motions recorded in Japan have the intensity to make base‐isolated high‐rise buildings in resonance with long‐period components and that careful treatment is inevitable in the structural design of these base‐isolated high‐rise buildings. It is pointed out that the friction‐type bearings are effective in general in avoiding the resonance with ground motions with a narrow‐range frequency characteristic, but are dangerous for ground motions with a wide‐range frequency characteristic in the long period range. Copyright © 2006 John Wiley & Sons, Ltd.     

橡胶垫隔震支座结构高宽比限值研究

本文对叠层橡胶垫隔震结构的高宽比限值进行了研究,导出了实用的简化计算公式,分析了地震动峰值、场地条件、隔震层刚度、上部结构刚度(反映了上部结构类型)、橡胶垫的布置等因素对隔震结构高宽比限值的影响及其变化规律。给出了不同条件下具有统计意义的隔震结构高宽比限值的定量范围,并提供了提高隔震结构高宽比的有效方法,得出了一些具有实际意义的结论,为工程计算与设计提供了方法和依据。本文结果可供编制有关规范和规程参考。     

并联复合隔震结构的地震响应和滞回特性分析

在建立并联复合隔震结构运动微分方程的基础上,通过数值模拟,计算并研究了不同加速度峰值下,给定摩擦承压比的多自由度并联复合隔震结构的自振周期、最大基底剪力、最大基底剪力系数、最大层间位移、层间速度、层间加速度等地震响应以及隔震层的滞回特性,并与普通抗震结构、夹层橡胶垫隔震结构、摩擦滑移结构进行了全面对比分析和讨论。结果表明:并联复合隔震结构由于充分利用了复合隔震支座的优点,能够显著降低结构的地震响应,并且具有优良的滞回耗能特性。     

基础隔震结构高宽比限值研究

本文研究目的是得到隔震结构在各种工况下的高宽比限值,这对隔震结构设计是必要的。橡胶隔震支座不能产生拉应力和隔震支座压应力不超过容许值是保证隔震结构在强震中不产生倾覆的充分条件。基于这两个条件,本文推导了隔震结构高宽比限值的显式并给出了针对不同建筑类别、不同设防烈度、不同场地条件和不同隔震层阻尼比的高宽比限值。在支座的轴力计算中,考虑了水平地震作用、竖向地震作用和重力荷载代表值的共同影响以及荷载的最不利组合。研究发现,当控制条件为支座不产生拉应力时,高宽比限值随隔震结构周期的增加而增加;当控制条件为支座压应力不超过容许值时,高宽比限值随隔震结构周期的增加而减小。因此,存在一个临界周期使高宽比限值取得极大值。研究还发现,存在一个最大的隔震结构周期使高宽比限值等于零或隔震层位移超过容许值。将隔震结构的周期与临界周期和最大隔震周期比较,就可以得到相应高宽比限值的表达式。