弹性滑移支座力学性能的试验研究

介绍了弹性滑移支座的原理、构造和特点;通过对其在不同工况下的性能试验,研究了竖向荷载、位移幅值以及加载频率对弹性滑移支座力学性能的影响,并给出了试验值与理论计算值之间的对比。研究结果表明：弹性滑移支座具有良好的工作性能,滞回曲线饱满,耗能能力强;竖向荷载和加载频率对弹性滑移支座的力学性能有一定的影响,而位移幅值对其影响较小;弹性滑移支座的恢复力模型,可以用考虑速度的指数摩擦力模型来描述,并且模拟得较为准确。     

基于磁悬浮理论的自适应抗拔摩擦摆隔震支座力学性能研究

为解决摩擦摆隔震支座抗拔能力不足的问题并优化其隔震性能,将传统的摩擦摆支座(FPB)和半主动控制思想相结合,提出一种自适应磁悬浮抗拔摩擦摆隔震支座(AMFPB)。基于磁路理论进行理论分析,推导出U型电磁铁的电磁力公式,以及AMFPB刚度、周期和等效阻尼比计算公式;对U型电磁铁进行位移-电磁力试验分析,建立AMFPB有限元模型,并对不同位移幅值、不同电磁铁匝数和输入电流下支座的滞回特性和抗拔性能进行分析。研究结果表明：U型电磁铁的位移-电磁力试验结果与理论结果吻合度较好,计算得到的AMFPB滞回曲线与数值模拟结果基本相同。AMFPB随滑动位移的增加可调节自身的刚度及耗能,有利于支座位移的控制。     

摩擦摆隔震支座理论分析与数值模拟研究

介绍了摩擦摆隔震支座的基本构成和隔震原理。利用力学平衡原理,对摩擦摆隔震支座进行了理论分析,推导了摩擦摆隔震支座的刚度和等效粘滞阻尼比,构造了摩擦摆隔震支座的滞回模型,并探讨了该支座的自回复能力,得到了其最大残余位移计算公式。采用有限元软件ABAQUS,对摩擦摆隔震支座进行实体单元建模,模拟低周反复荷载作用下,该支座的滞回特性与回复特性。研究结果表明：①理论分析和数值模拟结果吻合较好,验证了提出的滞回模型和最大残余位移计算公式的正确性;②摩擦摆隔震支座的滞回曲线饱满,具有良好的滞回性能;③摩擦摆隔震支座的刚度与球面半径成反比,可能的最大残余位移为摩擦系数和球面半径的乘积;④该支座的最大应力出现在支座处于设计位移的时刻,且一般位于滑块或支座板球铰面边缘。     

摩擦摆隔震支座振动台试验、数值仿真及应用研究

通过模型振动台试验和数值仿真,对适用于高层建筑结构的大吨位摩擦摆隔震支座在不同地震荷载工况下的动力响应和隔震性能进行了深入研究,试验模型的力学及承载性能在不同地震动水准下保持较好,且随着输入激励的增大,支座耗能能力逐渐提高,减隔震效果逐渐增强。隔震支座的数值模拟结果和振动台试验结果吻合良好,取得了较好的模拟效果。在此基础上,选取一复杂高层建筑结构作为研究对象,进行了不同地震波小震和大震激励作用下的动力响应分析,通过对比设置隔震支座与未设置隔震支座的计算结果,总结了高层建筑结构的动力响应规律。结果表明:(1)摩擦摆隔震支座耗能能力随着地震作用的增大而增强;(2)不同类型地震波作用对复杂高层建筑结构的响应明显不同:长周期地震波作用下结构响应明显比普通地震波作用下的结果大,且长周期地震波对结构位移响应的影响较加速度明显;(3)摩擦摆隔震支座对复杂高层建筑结构的地震反应有较为理想的隔震效果,不同地震波作用下结构响应的隔震效果有所不同,且不同响应之间的隔震效果也不相同,位移响应的隔震效果明显大于加速度的隔震效果。     

隔震支座非线性特性的数值模拟

对隔震支座进行精细的数值仿真是准确模拟隔震支座力学特性的基础。在确定天然橡胶本构模型参数的基础上,采用有限元软件建立了不同形状系数的隔震支座模型,并对支座施加竖向荷载和水平循环往复位移荷载情形进行了动力特性分析。分析结果表明,铅芯橡胶隔震支座的水平刚度随轴压应力的增大而降低,但是变化幅度不大,而水平刚度随第一、第二形状系数的增大而提高。结果还表明隔震支座的力学特性可以采用数值方法进行准确模拟。     

滞变—摩擦基底隔震支座的试验和模型

本提出了一种滞变－摩擦基底隔震支座。这种支座由钢棒和摩擦元件组成，钢棒容许摩擦元件水平滑动，同时又限制这种滑动；摩擦元件承受结构的竖向荷载，作完成了钢棒滞变恢复力特性的试验，并给出了钢棒的滞变恢复力模型的模型参数的计算公式，该模型与常用的折线模型有所不同，它仅用一个非线性微分方程来描述滞变恢复力，而不需要复杂的规则。     

浮放设备地震滑移反应数值模拟研究

以前人研究建立的浮放设备滑移反应分析理论为基础,给出了浮放设备在水平和竖向地震输入下滑移反应运动微分方程,选取连续型的库仑摩擦力模型,采用Runge-Kutta法求解浮放设备地震滑移反应运动微分方程,可以得到浮放设备在地震作用下的绝对加速度、相对速度和相对位移反应时程。采用编制的计算程序,进行了浮放设备地震滑移反应参数影响研究,结果表明:浮放设备水平滑移反应随着水平地震地面输入或楼层反应输入的增大而增大,随着设备与支撑面之间摩擦系数的增大而减小;当水平向输入加速度峰值大于0.3g时,需要考虑竖向激励的影响。     

滑移摩擦隔震系统在多向地面运动作用下的试验研究

基础隔震通常只考虑隔离水平地面运动，而对竖向地面运动的影响注意不够，本文进行了滑移摩擦隔震系统的振动台房屋模型试验，研究多向地面运动输入时上部结构反应和隔震系统的性能，试验中分别对模型输入了不同方向的地震动，其中包括水平单向、水平双向、水平和竖向及三向地震动输入，对试验结果进行了分析比较，结果表明竖向地震动输入对上部结构的水平地震反应有显著影响，同时在橡胶隔震支座中产生了竖向拉力。     

锈蚀钢筋混凝土框架柱滞回性能的数值模拟研究

以某钢筋混凝土框架柱为例,采用非线性有限元分析软件ABAQUS研究了框架柱在4种不同锈蚀程度(未锈蚀、轻微锈蚀、中等锈蚀和严重锈蚀)下的滞回性能,并与文献中描述的试验结果和框架柱的实际震害进行了对比。研究表明:钢筋锈蚀将导致框架柱的滞回承载力大幅度降低,而且随着锈蚀率的增大,这种承载力降低效应逐渐增强,其中锈蚀引起的钢筋与混凝土之间的粘结性能退化在这种滞回承载力削弱过程中起着重要的作用。就滞回曲线的特点来看,随着钢筋锈蚀程度的增大,框架柱滞回环的饱满程度降低、内缩增加,滞回曲线由弓形逐渐变成反S形,滞回环的包络面积变小,说明框架柱抗震耗能能力降低。     

SMA-橡胶支座的力学性能试验研究

SMA-橡胶支座是一种由叠层橡胶垫和形状记忆合金（SMA）复合而成的新型隔震支座。阐明了SMA-橡胶支座的设计思路和工作机理,通过SMA-橡胶支座实物模型的伪动力试验,考察了支座的水平和竖向刚度、耗能能力和等效阻尼比,研究了位移幅值、加载频率、竖向荷载等参数对支座力学性能的影响。研究结果表明,SMA-橡胶支座工作性能稳定,耗能能力较强,是一种性能优良的新型隔震装置。     

摩擦单摆支座等效摩擦系数数值仿真及试验研究

对摩擦单摆支座的主要参数等效摩擦系数进行了数值仿真及试验研究,为桥梁结构的减隔震设计提供了参考。数值仿真包括等效摩擦系数与滑动面和转动面的摩擦系数、竖向承载力及加载频率三者关系的研究,对比分析了模拟结果与试验结果。结果表明:当滑动面与转动面的摩擦系数为不同取值时,支座等效摩擦系数的模拟值略大于理论值,初步验证了支座等效摩擦系数理论公式的正确性;通过模拟结果与试验结果的对比分析,进一步验证了该理论公式的合理性。     

Dynamic analysis of sliding structures with unsynchronized support motions

The dynamic analysis of sliding structures is complicated due to the presence of friction. Synchronization of the kinematics of all the isolation bearings is often granted to simplify the task. This, however, may lead to inaccurate prediction of the structural responses under certain circumstances. Stepped structures or continuous bridges with seismic isolation are notable examples where unsynchronized bearing motions are expected. In this paper, a logically simple and numerically efficient procedure is proposed to solve the dynamic problem of sliding systems with unsynchronized support motions. The motion equations for the sliding and non‐sliding modes of the isolated structure are unified into a single equation that is represented as a difference equation in a discrete‐time state‐space form and the base shear forces between the sliding interfaces can be determined through simple matrix algebraic analysis. The responses of the sliding structure can be obtained recursively from the discrete‐time version of the motion equation with constant integration time step even during the transitions between the non‐sliding and sliding phases. Therefore, both accuracy and efficiency in the dynamic analysis of the highly non‐linear system can be enhanced to a large extent. Rigorous assessment of seismic structures with unsynchronized support motions has been carried out for both a stepped structure and a continuous bridge. Effectiveness of friction pendulum bearings for earthquake protection of such structures has been verified. Moreover, evident unsynchronized sliding motions of the friction bearings have been observed, confirming the necessity to deal with each of the bearings independently in the analytical model. Copyright © 2000 John Wiley & Sons, Ltd.     

Hybrid simulation of a multi‐span RC viaduct with plain bars and sliding bearings

This paper deals with the seismic response assessment of an old reinforced concrete viaduct and the effectiveness of friction‐based retrofitting systems. Emphasis was laid on an old bridge, not properly designed to resist seismic action, consisting of 12 portal piers that support a 13‐span bay deck for each independent roadway. On the basis of an OpenSEES finite element frame pier model, calibrated in a previous experimental campaign with cyclic displacement on three 1:4 scale frame piers, a more complex experimental activity using hybrid simulation has been devised. The aim of the simulation was twofold: (i) to increase knowledge of non‐linear behavior of reinforced concrete frame piers with plain steel rebars and detailing dating from the late 1950s; and (ii) to study the effectiveness of sliding bearings for seismic response mitigation. Hence, to explore the performance of the as built bridge layout and also of the viaduct retrofitted with friction‐based devices, at both serviceability and ultimate limit state conditions, hybrid simulation tests were carried out. In particular, two frame piers were experimentally controlled with eight‐actuator channels in the as built case while two frame piers and eight sliding bearings were controlled with 18‐actuator channels in the isolated case. The remaining frame piers were part of numerical substructures and were updated offline to accurately track damage evolution. Copyright © 2015 John Wiley & Sons, Ltd.     

摩擦-碟簧三维复合隔震支座的性能试验研究

对适用于大跨结构的摩擦-碟簧三维复合隔震支座进行了振动台试验研究,该支座在水平向和竖向分别采用摩擦滑移装置和碟型弹簧隔震。在水平向,试验重点测试了简谐激励和地震动激励下支座的滞回性能,考察了竖向荷载变化及地震动强度对隔震性能的影响,以期为建立水平隔震理论模型提供依据;在竖向,对碟型弹簧的等效阻尼比和等效刚度进行了测试,研究了竖向预压荷载和动力荷载对竖向滞回性能的影响。结果表明,复合隔震支座在水平向和竖向均具有较好的滞回性能,竖向等效阻尼比在0.10～0.15间,且随着预压荷载的增加而增大。     

Hysteretic models for sliding bearings with varying frictional force

The friction pendulum system is a sliding seismic isolator with self‐centering capabilities. Under severe earthquakes, the movement may be excessive enough to cause the pendulum to hit the side rim of the isolator, which is provided to restrain the sliding. The biaxial behavior of a single friction pendulum, in which the slider contacts the restrainer, is developed using a smooth hysteretic model with nonlinear kinematic hardening. This model is extended to simulate the biaxial response of double and triple friction pendulums with multiple sliding surfaces. The model of a triple friction pendulum is based on the interaction between four sliding interfaces, which in turn is dependent upon the force and displacement conditions prevailing at these interfaces. Each of these surfaces are modeled as nonlinear biaxial springs suitable for a single friction pendulum, using the yield surface, based on the principles of the classical theory of plasticity, and amended for varying frictional yield force, due to variation in vertical load and/or velocity‐dependent friction coefficient. The participation of the nonlinear springs is governed by stick‐slip conditions, dictated by equilibrium and kinematics. The model can simulate the overall force‐deformation behavior, track the displacements in individual sliding surfaces, and account for the ultimate condition when the sliders are in contact with their restrainers. The results of this model are verified by comparison to theoretical calculations and to experiments. The model has been implemented in programs IDARC2D and 3D‐BASIS, and the analytical results are compared with shake table experimental results. Copyright © 2013 John Wiley & Sons, Ltd.     

Multiple‐slider surfaces bearing for seismic retrofitting of frame structures with soft first stories

A new isolation interface is proposed in this study to retrofit existing buildings with inadequate soft stories as well as new structures to be constructed with soft first story intended for architectural or functional purposes. The seismic interface is an assembly of bearings set in parallel on the top of the first story columns: the multiple‐slider bearings and rubber bearings. The multiple‐slider bearing is a simple sliding device consisting of one horizontal and two inclined plane sliding surfaces based on polytetrafluoroethylene and highly polished stainless steel interface at both ends set in series. A numerical example of a five‐story reinforced concrete shear frame with soft first story is considered and analyzed to demonstrate the efficiency of the proposed isolation system in reducing the ductility demand and damage in the structure while maintaining the superstructure above the bearings to behave nearly in the elastic range with controlled bearing displacement. Comparative study with the conventional system as well as various isolation systems such as rubber bearing interface and resilient sliding isolation is carried out. Moreover, an optimum design procedure for the multiple‐slider bearing is proposed through the trade‐off between the maximum bearing displacement and the first story ductility demand ratio. The results of extensive numerical analysis verify the effectiveness of the multiple‐slider bearing in minimizing the damage from earthquake and protecting the soft first story from excessively large ductility demand. Copyright © 2012 John Wiley & Sons, Ltd.     

新型滑移隔震结构模型的振动台试验研究

利用实体软钢棒作为消能限位装置,将一种摩擦性能优良的二硫化钼材料作为隔震支座的滑移材料,提出并制作了一种可以应用于框架结构既能隔震又可以消能的新型摩擦滑移隔震装置。探讨了其设计方法和应用方法,并对安装了该新型摩擦滑移隔震装置的一相似比为1:5的5层框架结构模型进行了振动台试验,测试了框架结构在单向地震波作用下的地震反应规律,分析了摩擦滑移隔震结构的加速度反应、层间剪力反应、隔震层滑移量及隔震层剪力的变化规律。结果表明:一般情况下当设防烈度为8度,Ⅱ类场地时,该隔震结构的加速度响应可降低50%左右,层间剪力响应可降低50%左右,减震效果比较明显。另外,只要确定合理的构造方案和实施方案,这种新型摩擦滑移隔震装置就能满足框架结构的隔震减震要求,可应用于实际工程结构中。     

橡胶砂芯组合砌块动力特性及隔震效应数值分析

在混凝土空心砌块的空腔中填入橡胶砂形成的组合砌块（RSMCB）可作为简易隔震层应用于村镇建筑防震减灾。建立RSMCB的三维数值分析模型,进行循环剪切试验以及隔震分析,研究不同橡胶砂配比、竖向压应力、盖板尺寸和盖板埋深对隔震砌块动刚度和阻尼比的影响,分析不同的上部配重、输入地震波、橡胶砂配比、盖板尺寸和铺设方式对RSMCB垫层隔震效果的影响。结果表明:（1）橡胶砂芯组合砌块应变软化现象明显。（2）RSMCB的水平动刚度随橡胶砂配比增大而减小,随盖板埋深、盖板尺寸以及竖向压应力的增大而增大。（3）阻尼比随橡胶砂配比、竖向压应力、盖板尺寸和埋深的增大而减小,橡胶砂芯组合砌块隔震消能效果显著。在隔震数值模拟中,输入加速度在经过橡胶砂芯组合砌块垫层过滤后均有不同程度的降低,且被过滤掉大部分高频波。隔震效应随着盖板尺寸的增大而减小,上部结构配重越大,隔震效应越明显,橡胶砂配比为30%时RSMCB垫层隔震效应更好。橡胶砂芯组合砌块符合在村镇欠发达地区低成本隔震的要求,表现出广阔的应用前景。