近断层区桥梁组合使用板式橡胶支座和黏滞阻尼器方法探讨

选择具有脉冲性质的近断层区地震动记录和无脉冲地震动记录作为地震输入,考察了近场脉冲型地震动对我国常见的板式橡胶支座类型桥梁地震反应的影响。针对国内外抗震规范及学者提出的橡胶支座与黏滞阻尼器组合使用方法,研究了近场脉冲型地震动作用下板式橡胶支座桥梁组合使用黏滞阻尼器的减震效果,探讨了橡胶支座与黏滞阻尼器组合使用时可能存在的问题。结果表明,近场脉冲型地震动对桥梁结构地震反应影响明显,显著增大了板式橡胶支座桥梁的墩柱地震力、梁体地震位移及梁体残余位移;组合使用黏滞阻尼器方法虽能一定程度上控制梁体地震位移及残余位移,但同时以增大墩柱地震反应为代价;近场脉冲型地震动作用下,板式橡胶支座桥梁支座滑动后整桥体系缺乏自恢复力、震后存在梁体残余位移,组合使用黏滞阻尼器无法根本解决,可在支座与墩、梁间设置连接措施加以改善。     

近断层速度脉冲型地震动对多层校舍减震加固性能影响研究

近断层地震动具有加速度、速度脉冲运动特性,相对于普通地震动对结构可能造成更加不利的影响。本文针对典型多层校舍,对比了其黏滞消能减震加固前后的结构响应,研究了黏滞消能减震加固技术在不同地震动(近断层脉冲型地震动、近断层非脉冲型地震动和远场地震动)下的抗震性能和减震效果。首先,阐述了近断层地震动基本特征,并选择合适的地震动记录。随后,围绕某多层校舍开展了黏滞阻尼减震加固设计。最后,开展了多遇及罕遇地震下结构动力时程分析,对比、评价了结构抗震性能和可恢复性,以及阻尼器工作性能。研究结果表明,黏滞阻尼减震技术有效改善了结构抗震性能,罕遇地震作用下,结构薄弱层层间位移在各地震动工况平均衰减可达62.1%,薄弱层残余层间位移角平均减小71.3%;近断层脉冲型地震使结构产生明显大于同等强度普通地震(远场地震和近断层非脉冲地震)作用下的响应,罕遇地震作用下薄弱层层间位移角达远场地震工况的2.75倍,但黏滞阻尼减震效果受地震动特性变化影响较小。相关研究可为断层附近多层校舍抗震加固设计提供参考。     

黏滞阻尼器凸轮式响应放大单自由度减震体系的地震反应分析

为了研究黏滞阻尼器凸轮式响应放大装置的减震控制,基于对其工作机理和阻尼力计算公式的已有研究,建立了安装黏滞阻尼器凸轮式响应放大装置的单自由度体系运动方程和能量方程,对安装黏滞阻尼器的单自由度体系和安装黏滞阻尼器凸轮式响应放大单自由度体系进行了地震反应分析对比,包括:对具有相同阻尼系数的黏滞阻尼器,进行了多遇地震作用下的控制效果分析和能量分析;对El Centro波作用下具有相同位移控制效果的不同阻尼系数的黏滞阻尼器,进行了罕遇地震作用下的控制效果分析和能量分析.结果表明,该装置在不同强度地震作用下对位移、速度、阻尼力等响应具有明显的放大作用,安装阻尼系数较小的阻尼器可达到直接安装阻尼系数较大阻尼器相同的减震和耗能效果,且具有在不同强度地震作用下位移不失效的优点.     

黏滞阻尼器凸轮式响应放大单自由度减震体系的地震反应分析

为了研究黏滞阻尼器凸轮式响应放大装置的减震控制,基于对其工作机理和阻尼力计算公式的已有研究,建立了安装黏滞阻尼器凸轮式响应放大装置的单自由度体系运动方程和能量方程,对安装黏滞阻尼器的单自由度体系和安装黏滞阻尼器凸轮式响应放大单自由度体系进行了地震反应分析对比,包括:对具有相同阻尼系数的黏滞阻尼器,进行了多遇地震作用下的控制效果分析和能量分析;对El Centro波作用下具有相同位移控制效果的不同阻尼系数的黏滞阻尼器,进行了罕遇地震作用下的控制效果分析和能量分析.结果表明,该装置在不同强度地震作用下对位移、速度、阻尼力等响应具有明显的放大作用,安装阻尼系数较小的阻尼器可达到直接安装阻尼系数较大阻尼器相同的减震和耗能效果,且具有在不同强度地震作用下位移不失效的优点.     

带位移放大装置新型阻尼墙结构的地震响应分析

基于黏滞阻尼器的耗能原理,针对地震时阻尼器位移小的特点,提出一种可提高阻尼器耗能能力的位移放大装置,并在此基础上设计出一种黏滞阻尼墙。针对黏滞阻尼器力学模型,增设放大装置后,得到带放大系数的黏滞阻尼墙力学模型。以12层框架为例,利用有限元软件分析比较带放大装置的黏滞阻尼墙减震结构与常规阻尼器建筑结构的减震效率。在加速度、层间位移、层间剪力等地震响应的控制效果方面,基于文中提案采用放大装置的减震结构更为有效。     

同时附加位移和速度相关型阻尼的钢框架结构设计方法研究

在地震作用下,多高层钢框架结构主要发生剪切型变形,下部楼层相对位移较大,故应在下部楼层附加位移相关型阻尼器(如金属阻尼器).下部楼层附加金属阻尼器后对结构进行地震反应时程分析,可知上部楼层的层间速度明显大于下部楼层,因而可以在上部楼层附加速度相关型阻尼器(如黏滞阻尼器),如此就得到同时附加位移和速度相关型阻尼的钢框架消能减震结构.本文通过数值分析首先阐明同时附加位移和速度相关型阻尼的设计思想以后,介绍了基于等效线性化理论和减震性能曲线的消能结构设计方法,并利用此方法研究了结构同时附加金属阻尼器和黏滞阻尼器的消能减震结构设计方法.结果表明,该结构减震效果比仅附加金属或仅附加黏滞阻尼结构的减震效果要好.     

罕遇地震下石化钢结构减震的关键影响因素

在强烈地震作用下,炼油厂的石化钢结构可能发生破坏,导致较大的经济损失,并易引发严重的次生灾害。为降低石化钢结构的地震风险,结合石化钢结构的特点,以某大型炼油厂重整装置反应器为例,建立有限元分析模型,设置黏滞阻尼器进行罕遇地震下的减震设计,并分析了阻尼器的设置位置、数量和阻尼参数等影响因素。研究结果表明,黏滞阻尼器所在楼层的层间剪力和层间位移角显著减小,布置在结构底部的减震效果优于布置在中、上部;随着阻尼器数量的增加,层间剪力和层间位移角都会随之减小,但减少幅度逐渐降低;阻尼系数对石化钢结构减震效果的影响大于阻尼指数,减震设计中宜优先调整阻尼系数以获得较好的抗震性能。     

黏滞阻尼器减震结构地震反应分析的一种空间协同模型

如何控制结构在地震作用下的扭转作用是结构抗震设计中经常遇到的问题。采用建筑结构的空间协同模型动力分析方法,推导了黏滞阻尼器减震结构的附加阻尼矩阵、动力平衡方程,分析地震作用下高层钢结构中设置黏滞阻尼器的减震效果。改进后的程序能够计算黏滞阻尼器减震结构在双向地震波作用下的动力时程反应。空间力学模型可考虑局部楼板变形对结构地震反应的影响,考虑了错层结构、大底盘上部多塔结构、连体结构等复杂的结构形式,可沿任意角度输入相互垂直的两个水平地震动分量,可求解结构每层及结构构件和黏滞阻尼器的内力和变形。分析结果表明,黏滞阻尼器能够大量消耗地震输入能量,减小主体结构的地震反应。     

基于黏滞阻尼器的框架结构随机地震响应分析

考虑到地震动具有随机性,利用平稳过滤白噪声地震动模型,首先建立黏滞阻尼结构的动力方程,运用虚拟激励法将平稳随机地震激励转化为简谐振动分析,求解黏滞阻尼结构在随机地震作用下的响应,然后通过选用相同数量的阻尼器在最大层间位移处集中布置、循环布置、权数布置三种布置方案,对比分析布置前后结构的地震反应,得出最优的黏滞阻尼器空间位置布置方案。由此可知,黏滞阻尼器具有明显的减震效果,得到的黏滞阻尼器布置建议对抗震设计和加固具有参考意义,同时使用虚拟激励法能高效快捷的求出结构的随机响应。     

屈曲约束支撑与黏滞阻尼器的减震效果对比研究

以某钢筋混凝土框架结构工程实例为研究对象,选取与场地条件相匹配的地震动作为激励,在SAP2000程序中计算了该结构在多遇和罕遇地震作用下的非线性动力反应,并在框架结构模型中分别设置屈曲约束支撑和黏滞阻尼器。通过试算确定消能减震装置的参数,使得两种消能减震结构在多遇地震作用下的位移减震率均为40%。在此条件下,对比分析了结构的层间位移角、楼层加速度、基底剪力、柱轴力、塑性铰分布和各层阻尼器的工作状态。分析表明：在多遇地震作用下,屈曲约束支撑增大了结构的加速度响应,而黏滞阻尼器能够减小结构的加速度响应;在罕遇地震作用下,二者均能有效控制楼层的加速度响应,而屈曲约束支撑的位移减震效果更好,但黏滞阻尼器对框架柱内力的减少效果更为显著。     

近断层地震作用下混合阻尼隔震结构的响应分析

本文以实际的地震波El-Centro波为底波,在此基础上叠加三角型脉冲运动模拟近断层地震地面的激励;以人工合成的近断层地震波作为输入,研究其对混合阻尼隔震结构的动力反应特性,绘制了上部结构最大加速度和基底最大滑移量的时程图,并讨论了混合阻尼隔震结构的摩擦系数、粘滞阻尼比及滞回阻尼等参数对隔震结构产生的重要影响.研究表明:在混合阻尼隔震结构中,摩擦系数存在一个较优值,粘滞阻尼比对脉冲能量较大的B、C类波的控制有较显著的效果,但对原始波及A类波控制效果不明显,滞回阻尼对隔震结构Smax和amax均有一定影响,通过分析给出了该参数的合理取值.     

Earthquake response control of a super high‐rise structure subjected to long‐period ground motions via a novel viscous damped system with multilever mechanism

A novel viscous damped system and its principles are proposed in the paper. It is a novel viscous damped system with multilever mechanism that can improve the energy dissipation capacity of conventional viscous dampers. In order to compare the damping effects of the novel viscous damper with that of the conventional viscous damper, a shaking table test of a three‐story steel frame structure is performed. Testing results indicate that the novel viscous damped system is more efficient. The elastic time‐history analysis of a super high‐rise frame‐core tube structure is studied under the frequently occurring earthquake. Dynamic loads take two groups of ground motions with different period characteristics into account. Main response values such as base shear, interstory drift, and acceleration factor under long‐period ground motions are apparently larger than the seismic results due to standard ground motions. Responses between the undamped structure and the damped structure with conventional viscous dampers or the latest products are compared. It is concluded that the proposed viscous damped system can perform more effectively in reducing high‐rise structural responses subject to long‐period ground motions.     

对称双塔连体结构采用粘滞流体阻尼器的消能减震分析

根据双轴对称双塔连体结构在水平地震作用下的受力和变形特点,在连体位置设置斜向粘滞流体阻尼器对结构进行消能减震。分析了结构各种响应随阻尼系数的变化情况,结果表明存在一个最优的阻尼系数使得结构的响应取得最小值。在对阻尼系数进行优化的基础上,详细研究了结构在小震和大震下的减震效果,计算表明,在采用最优阻尼系数的条件下,结构的最大层间剪力、层间相对位移和楼层位移等各指标都有较好的减震效果。但在大震作用下,由于结构进入塑性后本身的阻尼比增加了,阻尼器的耗能比例相对降低,其减震效果没有小震时明显。     

北京A380机库采用粘滞阻尼器的减振控制分析

为研究大跨度网架机库结构的减振控制效果,采用粘滞阻尼器作为减振装置,在三向地震波输入下,对北京A380机库进行减振控制分析。以减小屋盖结构节点竖向位移为减振控制目标,分别在网架结构、抗侧力结构以及网架和抗侧力结构中布置粘滞阻尼器,并进行不同控制方案的比较。结果表明,在网架结构中布置阻尼器时,非线性阻尼器和线性阻尼器的控制效果基本相同,"替换方式"布置阻尼器的控制效果好于"附加方式",替换下弦与中弦之间腹杆的减振效果好于替换中弦与上弦之间的腹杆,在网架四边中部布置阻尼器的控制效果优于在四边均匀布置或布置在无控结构竖向位移最大的节点周围,阻尼器数量宜适中;抗侧力结构中布置阻尼器的控制效果优于布置在网架结构中;网架与抗侧力结构均布置阻尼器,可进一步提高减振控制效果。研究成果可为大跨度网架结构采用粘滞阻尼器减振控制提供参考。     

Analysis of seismically-isolated two-block systems using a multi–rocking-body dynamic model

A novel multibody rocking model is developed to investigate the dynamic response of two stacked rigid blocks placed on a linear base isolation device. The model is used to investigate the dynamic response of a realistic statue-pedestal system subject to pulse-like ground motions. The analysis shows that, in general, base isolation increases the safety level of the rocking system. However, for large period pulses or small size blocks, the isolator can amplify the ground motion, resulting in a lower minimum overturning acceleration than for the nonisolated system. Further, the amplification or shock spectrum of a linear mass-dashpot-spring oscillator, was found to be the reciprocal of the minimum nondimensional overturning acceleration of the investigated rocking system. Novel rocking spectra are obtained by normalizing the frequency of the pulse by the frequency of the isolator. The analysis also demonstrates how the dynamic response of the two stacked blocks is equivalent to that of a single-block configuration coincident with the whole system assumed monolithic or the upper block alone, whichever is more slender.     

Response of vibration-isolated object to ground motions with intense vertical accelerations

This paper reports the results of shaking table tests performed to assess the response of an object placed on a vibration isolator to intense ground motions whose peak accelerations are close to or over the gravity acceleration in both vertical and horizontal directions. The passive vertical and horizontal vibration isolator, developed by the authors, has rolling load-bearing elements and constant-force springs to provide piecewise-constant restoring forces. First, we performed shaking table tests, wherein only the horizontal vibration was isolated. An unexpected finding from the tests is that, when the vibration isolator was subjected to ground motions with intense vertical accelerations, not only vertical but also horizontal accelerations were amplified. This led to a large rocking response or overturning of the object placed on the vibration isolator. A likely reason for the amplification is rocking of the upper portion of the vibration isolator above the rolling load-bearing elements induced by intense vertical accelerations. Next, we performed shaking table tests, wherein both vertical and horizontal vibrations were isolated. In this case, the vertical as well as horizontal accelerations were significantly reduced and the rocking response of the vibration-isolated object was suppressed. These results suggest potential risks in conventional horizontal vibration isolators having rolling load-bearing elements when they are subjected to ground motions with intense vertical accelerations. The results also demonstrate the effectiveness of vertical vibration isolation to avoid such risks.     

墙式连接金属阻尼器RC框架振动台试验研究

为研究金属阻尼器墙式连接方式的有效性,检验金属阻尼器对RC框架的减震效果,设计并制作1/4缩尺的4层无控结构(纯框架)和减震结构(设置金属阻尼器)振动台试验模型。选取一条人工合成地震动和Takatori天然地震动,调幅到不同地震动强度进行振动台试验,对模型结构动力特性(自振频率、阻尼比)和结构响应(位移、加速度、剪力)进行对比研究。试验结果表明：金属阻尼器同时给结构提供附加刚度和附加阻尼,减震结构的整体刚度始终大于无控结构,减震结构的阻尼比相比于无控结构大幅增加,减震结构的位移响应控制效果显著。金属阻尼器的墙式连接形式具有足够的稳固性和有效性,小震下连接部位无损伤,中震下连接部位出现细微裂缝,大震下结构梁与墙肢交界处出现剪切裂缝,但仍能够保证连接的可靠性。基于试验数据得到的阻尼器位移占比为0.4～0.6,在后续研究中,应进一步研究如何保证较大的阻尼器位移占比,以充分发挥阻尼器的作用。此外,近断层地震动对结构地震响应的影响仍需进一步研究。     

Cost-benefit analysis of seismic-isolated structures with viscous damper based on loss estimation

This paper presents a methodology to utilise performance-based seismic design procedure for evaluating isolated structures with or without viscous dampers (VD) considering cost-benefit analysis. A non-linear four-story archetype of conventional steel structure, a lead-rubber-bearing isolated structure and a natural rubber-bearing isolated structure with the linear VD are compared with each other under far-field (FF) and near-field (NF) ground motions. Also, loss parameters, such as expected annualised loss, expected annualised repair time, expected annualised fatalities and expected annualised injuries based on loss estimation process, are utilised for evaluating the structures. Sensitivity analysis is used to study the effect of modelling uncertainty variations in the loss estimation process. It has been found that the effectivity of supplemental damping for low damping isolated structures increases in the NF comparing with the FF ground motions. Finally, the cost-benefit analysis is done to calculate payback period of investment for additional cost of the isolation system with or without the supplemental damping. The advantage of loss estimation is an improved method to evaluate the effectiveness of the isolation system in terms of loss parameters that are useful in the cost-benefit studies and for determining rational insurance premiums.     

Effects of near-fault ground motions and equivalent pulses on multi-story structures

The focus of this paper is the structural response of multi-story structures to near-fault ground motions, and whether structural response is dominated by the ground motion pulses present in forward-directivity ground motions. Also considered is whether simplified pulses are capable of representing the effects of these pulses on structural response. Incremental Dynamic Analysis was employed to assess the effects of forward-directivity pulses on the response of near-fault multi-story structures. Three different generic multi-story shear buildings were subjected to fifty four near-fault ground motions including ordinary and forward-directivity records. The Maximum Story Displacement Ductility Demand was selected as the Engineering Demand Parameter. Results showed that pulse-like forward-directivity ground motions impose a larger ductility demand to the structure compared to ordinary ground motions. Moreover, the response of the structures to forward-directivity motions shows higher scatter than the response to ordinary ground motions when correlated with simple intensity measures such as PGA or spectral acceleration at the first mode period. The only intensity measure that appears to be valid for both ordinary and forward-directivity ground motions is the peak ground velocity. The structural response to the forward directivity ground motions was reproduced using an equivalent pulse model based on the modified Gabor Wavelet pulse. It is shown that when the ratio of pulse period to the fundamental structural period falls in a range of 0.5-2.5, the equivalent pulse model appropriately represents the structural response to forward-directivity ground motions. The simplified pulse parameters can be predicted using existing relationships and can be incorporated into probabilistic seismic hazard analysis to develop a seismic reliability analysis. Finally, the effects of damping ratio and P-Δ were investigated for forward-directivity ground motions. The effect of variations in the damping ratio on the ductility demand was insignificant while P-Δ-effects on the ductility demand are significant.     

减震结构粘滞阻尼器参数优化分析

研究了基于响应面法进行减震结构非线性粘滞阻尼器参数优化设计的方法,该方法包括试验设计、有限元分析、响应面函数拟合和参数优化.以一榀钢筋混凝土框架结构非线性粘滞阻尼器参数优化为例,以所有粘滞阻尼器提供的阻尼力之和最小为优化目标函数,层间最大位移限值作为约束条件,建立粘滞阻尼器参数优化的数学模型,然后运用非线性规划优化方法进行参数优化.算例研究结果表明:基于响应面法进行粘滞阻尼器参数优化,既能保证结构层间位移小于限值,又能降低建造成本.