地震力作用下影响巨子型有控结构的动力参数研究

附加柱刚度与附加阻尼为影响巨子型有控结构抗震性能的两个重要参数。本文基于随机振动理论探讨水平地震作用下附加柱刚度及附加阻尼对巨、子结构动态特性的影响,分析附加阻尼与附加柱间的制约关系,并对比研究传统巨型框架结构、巨子型有控结构安装流体阻尼器前后的响应功率谱变化。结果表明:巨子型有控结构具有极好的抗震性能,安装合理的附加阻尼后,其抗震能力得到进一步提高;附加柱刚度变化不但影响巨、子结构动力响应,而且会导致最优附加阻尼区间迁移。因此,巨子型有控结构具有广阔的发展空间,实际设计中应充分考虑附加柱与附加阻尼的相互影响。     

黏滞阻尼器对拉索参数振动的控制分析

提出采用黏滞阻尼器对拉索参数振动进行控制,建立了黏滞阻尼器控制拉索参数振动的运动方程。从频域和时域以及起振幅值等角度,研究了最优黏滞阻尼器对不同垂度拉索参数振动的控制效果;此外,还研究了最优黏滞阻尼器安装位置对拉索参数振动控制效果的影响。研究表明,黏滞阻尼器可以有效控制拉索的参数振动,控制效果与拉索的激励幅值、最优阻尼器的安装位置和斜拉索的垂度有关。激励幅值越大,控制效果一般越差;最优阻尼器的安装位置越靠近跨中,则控制效果越好;黏滞阻尼器对大垂度拉索的控制效果不及对小垂度拉索的控制效果。     

独塔自锚式悬索桥纵向设置黏滞阻尼器参数分析

以鼓山大桥为工程背景,研究黏滞阻尼器对该桥抗震性能的影响。利用非线性动力时程分析的方法讨论了黏滞阻尼器参数C及ξ的不同组合对该桥塔底、墩底、梁端及塔顶等关键部分内力及变形的影响规律。综合考虑桥梁结构各个关键部位的反应情况,得出该桥的拟安装阻尼器的最优参数约为C=1500kN／（m·s）^0.3,ξ=0．30左右。分析结果表明：在纵桥向设置适当参数的阻尼器可有效减小纵桥向位移的同时改善关键构件受力。     

在振动台模型试验中黏滞阻尼器的设计方法

通过有限元分析,计算出原型结构中黏滞阻尼器的合理参数,然后利用阻尼力相似原则,对原型结构中黏滞阻尼器参数进行相似比运算,转化为模型结构中的黏滞阻尼器参数.运用该方法,在连续梁桥纵向消能减震振动台试验中设计模型黏滞阻尼器,从试验结果来看,黏滞阻尼器发挥了良好的消能减震效果.     

设置黏滞阻尼器的连体高层结构的减振研究

研究采用阻尼器对连体高层结构的地震响应进行振动控制。首先从结构动力方程出发,推导了在主塔与连廊之间设置有黏滞阻尼器的有控结构的基本振动控制方程;进而通过数值模拟,以某实际工程为原型,尝试将连廊与主塔间的斜撑利用黏滞阻尼器进行替换,分别在不同地震激励下比较了有控结构和无控结构的地震响应。分析结果表明,采用黏滞阻尼器可以有效降低结构的层剪力、结构位移、加速度等地震响应;同时能量分析的结果也表明本文采用的减振方案在不同地震激励下都可以有效耗散地震能量,由此得出结论采用黏滞阻尼器提高连体高层结构的抗震安全性是可行的。     

近断层脉冲型地震动作用下黏滞阻尼器减震结构能量分布与耗散研究

为研究近断层脉冲型地震动对黏滞阻尼器减震结构抗震性能的影响,从结构在地震动作用下的能量分配与耗散机制角度进行探讨分析。基于结构能量平衡原理,利用MATLAB软件编写减震结构能量响应求解程序,利用该程序计算分析减震结构与无控结构在不同近断层脉冲型地震动作用下的能量分布特点,并分析减震结构在近断层非脉冲型和脉冲型地震动作用下的能量分布与结构变形的差异性,进一步揭示脉冲周期Tp对减震结构塑性耗能分布的影响规律。研究结果表明,在不同近断层地震动作用下,附设黏滞阻尼器的减震结构表现出了不同的减震效果,其塑性变形程度受结构自振周期与脉冲周期之比的影响较显著。当结构在遭遇地震之前的基本周期与脉冲周期之比T0/Tp接近于1时,结构因共振效应导致其塑性变形显著增大,其地震损伤程度较严重;当T0/Tp远大于1,或当T0/Tp小于1且结构在遭遇地震之后的基本周期与脉冲周期之比T1/Tp同时远小于1时,减震结构可避开共振频段,其塑性变形显著减小,且在近断层脉冲型地震动作用下的抗震性能得到提高。     

新型舌板黏滞阻尼器力学性能试验研究

本文提出了一种新型舌板黏滞阻尼器,通过对该黏滞阻尼器进行低周循环加载试验和抗低周疲劳性能试验,研究并验证了该阻尼器的耗能性能、抗低周疲劳性能及恢复力模型。研究结果表明:选取合适参数的舌板式黏滞阻尼器滞回曲线饱满,耗能性能与抗低周疲劳性能良好。Maxwell模型能够较好地描述该阻尼器力学行为,反映阻尼器在各种试验工况下的出力情况。该阻尼器设计与加工简单,对工程结构的耗能减震有着实际意义。     

非线性黏滞阻尼减震结构基于位移的设计方法

结合我国抗震设计规范,提出非线性黏滞阻尼减震结构基于位移的设计方法.根据减震结构的特点,将其性能划分为使用良好、人身安全和防止倒塌3个水平,并用层间位移角限值予以量化;以简化的方法计算非线性黏滞阻尼器的等效阻尼比.在此基础上将结构转化为等效单自由度体系,利用基于位移的设计方法对非线性黏滞阻尼减震结构进行设计,通过算例,介绍用该方法对框架结构进行非线性黏滞阻尼减震设计的设计过程.实例分析表明,提出的非线性黏滞阻尼减震结构基于位移的设计方法是可行的,并且与时程分析得出的平均结果吻合较好,而且该方法简单实用,便于操作,能够控制减震结构在不同强度水准地震作用下的性能.     

黏滞阻尼器连接相邻结构减震优化分析

阻尼器参数的确定是利用阻尼器连接相邻结构进行减震设计的关键.根据随机地震反应理论,以相邻结构的频率比和质量比为参数,推导了结构位移反应均方差与连接阻尼比的关系式,得到了相邻结构的地震反应与频率比、质量比以及连接阻尼比的影响规律,从而得到了连接阻尼器的优化设计参数.根据自振频率相等的原则,探讨了将多自由度体系简化为单自由度体系的分析方法.最后在El Centro波、Taft 波及人工波激励下,对比分析了某相邻10层建筑结构有连接和无连接时的地震反应,表明黏滞阻尼器连接相邻结构具有较好的减震效果.本分析方法可供相邻结构减震设计参考.     

双向地震波作用下巨子型有控结构建筑的隔震设计

为了增强巨子型有控结构建筑的动力特性,提升其稳定性,设计双向地震波作用下建筑有控结构。采用3种磁流变阻尼器(MRD)与滑移隔震混合控制结构构成单体建筑有控结构,其包括巨结构和子结构,并建立该有控结构的动力分析模型。在动力分析模型中输入水平和竖向地震,得到模型的竖向和水平滑动状态运动微分方程,依据这两个方程采用自适应模糊神经网络优化动力分析模型,构建优化模型。从优化模型出发,通过实例实验分析得出,优化设计双向地震波作用下建筑有控结构时,在其上部结构层间和隔离层各安装一个MRD,可确保优化设计后的有控结构在不同双向地震工况下的地震反应控制效果最佳,且有控结构在双向地震工况2下,结构第一层、中间三层以及顶层的加速度和位移的时程曲线走向一致,且差距微小;同时有控结构的巨结构顶层侧移响应随着子结构刚度增加而提高,动力特性没有明显的变化,子结构随着其自身刚度增加顶层侧移响应表现稳定,子结构动力特性增强。     

非线性粘滞阻尼器消能结构设计方法探讨

在建立非线形粘滞阻尼器消能结构性能曲线的基础上，建议了依据减震性能目标确定阻尼器参数的概略设计方法。提出了多自由度非线性粘滞阻尼器消能结构的等效阻尼比计算公式。在此基础上建议了适用于多自由度非线性粘滞阻尼器消能结构地震反应预测的模态叠加法，方法与时程分析结果对比吻合良好。为使各层阻尼器参数更好地满足减震性能要求，提出了将概略设计得到的层阻尼器参数依据减振性能目标进行调整的方法。     

A two‐step direct method for estimating the seismic response of nonlinear structures equipped with nonlinear viscous dampers

The insertion of fluid viscous dampers in building structures is an innovative technology that can improve significantly the seismic response. These devices could be very useful also in the retrofit of existing buildings. The effect of this typology of damping system is usually identified with an equivalent supplemental damping ratio, which depends on the maximum displacement of the structure, so that iterative procedures are required. In this paper, a simplified direct assessment method for nonlinear structures equipped with nonlinear fluid viscous dampers is proposed. The method proposed in this study is composed by two steps. The first one yields the direct estimate of the supplemental damping ratio provided by nonlinear viscous dampers in presence of a linear elastic structural response. The second step extends the procedure to structures with nonlinear behavior. Both graphical and analytical approaches have been developed. The proposed method has then been verified through several applications and comparisons with nonlinear dynamic analyses. Moreover, an investigation has been performed with regard to the influence of the relations that define the damping reduction factor and the hysteretic damping. Copyright © 2014 John Wiley & Sons, Ltd.     

Seismic retrofitting of braced frame buildings by RC rocking walls and viscous dampers

A design procedure for seismic retrofitting of concentrically and eccentrically braced frame buildings is proposed and validated in this paper. Rocking walls are added to the existing system to ensure an almost uniform distribution of the interstorey displacement in elevation. To achieve direct and efficient control over the seismic performance, the design procedure is founded on the displacement‐based approach and makes use of overdamped elastic response spectra. The top displacement capacity of the building is evaluated based on a rigid lateral deformed configuration of the structure and on the ductility capacity of the dissipative members of the braced frames. The equivalent viscous damping ratio of the braced structure with rocking walls is calculated based on semi‐empirical relationships specifically calibrated in this paper for concentrically and eccentrically braced frames. If the equivalent viscous damping ratio of the structure is lower than the required equivalent viscous damping ratio, viscous dampers are added and arranged between the rocking walls and adjacent reaction columns. The design internal forces of the rocking walls are evaluated considering the contributions of more than one mode of vibration. The proposed design procedure is applied to a large set of archetype braced frame buildings and its effectiveness verified by nonlinear dynamic analysis.     

Direct displacement-based design for seismic retrofit of existing buildings using nonlinear viscous dampers

This paper presents a direct displacement-based design procedure for seismic retrofit of existing buildings using nonlinear viscous dampers according to equivalent linear systems. Unlike conventional methods, the equivalent linear viscous damping provided by the nonlinear viscous dampers is derived based on the assumption that the average energy dissipated between the linear and the nonlinear viscous dampers is equal. Also, the equivalent period and viscous damping for the equivalent linear systems which are used for representing the behavior of bare frames (the buildings without dampers) are derived from the concept of average storage energy and average dissipated energy, respectively. It is shown from nonlinear time-history analyses that the nonlinear action of the retrofitted structures can be reasonably captured by the presented direct displacement-based procedure.     

Optimal design of supplemental viscous dampers for linear framed structures

A methodology for the optimal design of supplemental viscous dampers for framed structures is presented. It addresses the problem of minimizing the added damping subject to a constraint on the maximal interstorey angular drift for an ensemble of realistic ground motion records while assuming linear behaviour of the damped structure. The solution is achieved by actually solving an equivalent optimization problem of minimizing the added damping subject to a constraint on a maximal weighted integral on the squared angular drift. The computational effort is appreciably reduced by first using one ‘active’ ground motion record. If the resulting optimal design fails to satisfy the constraints for other ground motions from the original ensemble, additional ground motions (loading conditions) are added one by one to the ‘active’ set until the optimum is reached. An efficient selecting process which is presented herein will usually require one or two records to attain an optimum design. Examples of optimal designs of supplemental dampers are presented for a 2‐storey shear frame and a 10‐storey industrial frame. The 2‐storey shear frame is required to withstand one given ground motion whereas the 10‐storey frame is required to withstand an ensemble of twenty ground motions. The resulting viscously damped structures have envelope values of interstorey drifts equal or less than the target drifts. Copyright © 2005 John Wiley & Sons, Ltd.     

On the efficiency of viscous dampers in reducing various seismic responses of wall structures

This paper rigorously assesses the efficiency of viscous dampers connecting two walls to result in “viscously coupled shear walls”. This assessment also holds for viscous dampers in wall structures as they are mounted on frames parallel to the walls leading to “wall-viscous frame” systems. A continuum approach is adopted to model the structure so as to enable non-dimensional formulation of the governing equations. Those equations reveal that, under the approximations considered, the system damping ratio (defined here by 0.5 sqrt(c^2/(m*EI))) is a convenient compact single parameter controlling the response reduction w.r.t. the response of the corresponding undamped system. In contrast to coupled shear walls, this controlling parameter does not depend on the height of the building; therefore, the viscously damped system is efficient for low-rise buildings as well. The continuum approach also allows a semi-analytical solution of the eigenproblem in the complex domain followed by a complex modal spectral analysis. Those solutions reveal the efficiency of the added damping in reducing not only the displacements, inter-story drifts, and wall moments but also the absolute accelerations, wall shear, total shear, and total overturning moments. The results of the analyses and the non-dimensional tables and graphs developed for important response parameters lead to a simple method that could easily be implemented in practice for the purpose of initial design. Copyright © 2012 John Wiley & Sons, Ltd.     

高层建筑结构中粘滞阻尼器的新型安装方式

在建筑结构中,一般粘滞阻尼器均布置在层间,但在有些情况下较小的层间位移差在一定程度上制约了阻尼器性能的充分发挥。系统回顾了为解决这一问题,目前最新的一些解决方案:改进层间阻尼器的连接方式,如基于连杆结构、杠杆原理与齿轮机构的位移放大系统,及大对角支撑;新型结构保护系统,如利用结构构件竖向振动位移及框架核心筒结构的加强层阻尼系统等,并重点分析了加强层阻尼系统。     

黏滞阻尼器在单层网壳结构中的优化布置

目前采用黏滞阻尼器对单层网壳结构进行减振控制时,阻尼器最优布置位置通过试算确定。针对此问题,推导了地震作用下黏滞阻尼器耗能公式,提出了以能量比例系数为评价指标的阻尼器优化布置准则。以单层球面网壳和单层柱面网壳为例,对比分析了地震作用下分别采用优化布置准则与现有布置方式布置阻尼器时结构最大节点位移减振系数,验证了所提出优化布置准则的正确性及在单层球面网壳和单层柱面网壳中的适用性。     

Fail-safe optimization of viscous dampers for seismic retrofitting

This paper presents a new optimization approach for designing minimum-cost fail-safe distributions of fluid viscous dampers for seismic retrofitting. Failure is modeled as either complete damage of the dampers or partial degradation of the dampers' properties. In general, this leads to optimization problems with large number of constraints. This may result in high computational costs if all the constraints are simultaneously considered during the optimization analysis. Thus, to reduce the computational effort, the use of a working-set optimization algorithm is proposed in this paper. The main idea is to solve a sequence of relaxed optimization subproblems with a small subset of all constraints. The algorithm terminates once a solution of a subproblem is found that satisfies all the constraints of the problem. The retrofitting cost is minimized with constraints on the interstory drifts at the peripheries of frame structures. The structures considered are subjected to a realistic ensemble of ground motions, and their response is evaluated with time-history analyses. The transient optimization problem is efficiently solved with a gradient-based sequential linear programming algorithm. The gradients of the response functions are calculated with a consistent adjoint sensitivity analysis procedure. Promising results attained for 3-D irregular frames are presented and discussed. The numerical results highlight the fact that the optimized layout and size of the dampers can change significantly even for moderate levels of damage.     

基于粘滞阻尼器的元江大桥减震设计方案

为了提高大跨度桥梁的抗震性能水平,基于粘滞阻尼器的结构减震控制技术成为专家学者研究的重点和工程设计人员首先考虑的抗震设防措施。现有成果主要集中在大跨度公路斜拉桥的研究和应用,在山区的非规则高墩钢桁连续梁桥研究的较少。以云南省元江大桥为例,采用Midas/civil建立弹性分析的有限元模型,对元江大桥进行了动力特性分析。采用快速非线性时程分析方法对粘滞阻尼器参数进行了优化分析,并且总结了粘滞阻尼器参数对高墩连续梁桥的减震作用规律。最后,通过有控和无控结构的地震动响应对比分析,评价了安装阻尼器后的结构主控部位的减震效果。结果表明:减震控制提高了结构的安全性。