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。     

金属橡胶支座剪切性能试验研究

针对一种金属橡胶支座,研究其剪切性能.进行3种压应力下的拟静力试验,分析竖向压力和水平剪切变形对支座剪切性能的影响;以试验数据为基准,建立支座剪切性能与压应力之间的相关性经验公式,提出能够近似模拟试验曲线的三线性恢复力模型.试验研究表明,随着支座剪切变形的增大,支座等效刚度及耗能增大,等效阻尼比减小,屈服力基本保持不变...     

环境温度对板式橡胶支座摩擦滑移性能的影响分析

采用有限元模拟的方式,对板式橡胶支座摩擦滑移特性进行分析,并与常温试验中获得的支座摩擦滑移滞回曲线、等效黏滞阻尼比等进行了对比.在获得可靠模型的基础上,分析环境温度对板式橡胶支座摩擦滑移特性的影响,研究了温度与支座摩擦滑移耗能、等效黏滞阻尼比和滑动起始距离的关系.结果表明:(1)板式橡胶支座的有限元模型可以较好地实现支...     

新型弹塑性软碰撞防护装置试验研究

为限制隔震层位移,研发了同时提供刚度和阻尼力的新型弹塑性软碰撞防护装置,该装置主要由铅芯橡胶支座、剪力键及中空连接钢板组成。首先对铅芯橡胶支座进行了设计压应力12MPa下基本性能试验及压应力0 MPa下剪切试验;然后进行了弹塑性软碰撞防护装置的水平力学性能测试试验,测定装置的屈服后刚度、屈服力及支座顶端转角,探讨了剪力键外圆面罩橡胶套对试验结果的影响,对比分析了装置的水平力学性能指标与支座在0MPa下剪切试验结果的差异;最后,对弹塑性软碰撞防护装置进行了数值模拟,对比了数值模拟与试验的水平力-位移滞回曲线。结果表明:弹塑性软碰撞防护装置可提供刚度及阻尼力,在剪力键外圆面罩上橡胶套后对试验结果基本无影响;与0MPa下支座测试结果相比较,装置的屈服后刚度及屈服力有所降低;支座顶端转角随支座剪应变的增大而增大;数值模拟与试验的滞回曲线吻合良好,该装置具有良好的滞回耗能能力。     

两种减隔震支座动力参数的设计方法及减隔震效果差异研究

为探讨强震区梁式桥减隔震支座的合理设计问题,根据设计经验归纳总结了铅芯橡胶和摩擦摆两种减隔震支座动力参数的一般设计方法及流程;针对实桥给出了两种支座的详细动力设计参数,并对参数进行了敏感性分析;根据时程分析结果对减隔震效果差异进行了对比,运用等效线性化理论解释了差异的内在原因。研究结果表明:支座摩擦系数并不是越大越有利,而应通过分析确定;由于铅芯橡胶与摩擦摆支座等效刚度值的明显不同,导致随着地震作用的提高结构内力响应差别将逐渐减小,而梁端位移响应差别呈显著增大趋势;建议高烈度区桥梁减隔震支座选型宜选用铅芯橡胶支座。     

基于状态空间法的SMA-复合支座隔震结构分析

研究了SMA(shape memory alloy)绞线-叠层橡胶复合支座的工作原理,将结构控制理论中的结构状态空间法应用到该复合支座隔震结构的数值模拟分析中。建立了普通框架、安装叠层橡胶支座和安装SMA复合支座框架的结构状态方程,应用SIMULINK工具箱建立结构仿真模型,得出不同条件下框架结构的时程反应曲线。通过对比分析可以看出SMA-复合支座能很好地改变结构的隔震效果,应用状态空间法进行SMA-复合支座隔震结构的数值模拟分析简单准确。     

挡土墙地震反应非线性波动模拟

本文运用解耦近场非线性波动数值模拟方法研究挡土墙地震反应，为反映墙土体系在地震作用下的位移机制，引入了Desai薄层单元模拟墙土间接触面，并采用双线型本构关系作为接触面单元和土体的非线性模型，在此基础上给出了解决P—SV问题的非线性显式有限元时域递推公式，为进一步发展非线性波动数值模拟技术提供了有益经验。为验证本文方法及适用性，将数值模拟结果与Zeng，X．和Madabhushi，X．P．G．等的离心机试验和弹塑性数值模拟结果进行对比。结果表明：墙土体系加速度、挡土墙顶底相对滑移、沉降和墙体倾角等同离心机试验模拟结果基本吻合，与弹塑性数值模拟结果相似。     

楼面滑动隔震装置设计与试验研究

设计了一种由滑动型和普通型橡胶支座组合而成的楼面隔震装置，通过振动台试验验证，滑移时的摩擦系数约为0．01－0．03，装置的隔震力学行为可以用双线性模型来模拟，只要第二刚度设计得当，这种装置的隔震效果可达50％－80％。     

基于通用有限元软件的混合模拟试验两种实现方法与分析

根据混合模拟试验理论,将其基于通用有限元软件的实现方式归结为分离式及整体式。为了对比分析这两种实现方法,利用MATLAB编写数值积分算法及与OpenSees的数据接口程序,并应用其在局域网内的网络通讯功能,建立了混合模拟试验的数值仿真系统。通过对单自由度结构和多自由度结构的模拟试验进行的分析和验证,对比分析了两种实现方法的利弊,为后续实验室进行物理试验提供参考依据。     

Characterizing friction in sliding isolation bearings

The force–displacement behavior of the Friction Pendulum? (FP) bearing is a function of the coefficient of sliding friction, axial load on the bearing and effective radius of the sliding surface. The coefficient of friction varies during the course of an earthquake with sliding velocity, axial pressure and temperature at the sliding surface. The velocity and axial pressure on the bearing depend on the response of the superstructure to the earthquake shaking. The temperature at an instant in time during earthquake shaking is a function of the histories of the coefficient of friction, sliding velocity and axial pressure, and the travel path of the slider on the sliding surface. A unified framework accommodating the complex interdependence of the coefficient of friction, sliding velocity, axial pressure and temperature is presented for implementation in nonlinear response‐history analysis. Expressions to define the relationship between the coefficient of friction and sliding velocity, axial pressure, and temperature are proposed, based on available experimental data. Response‐history analyses are performed on FP bearings with a range of geometrical and liner mechanical properties and static axial pressure. Friction is described using five different models that consider the dependence of the coefficient of friction on axial pressure, sliding velocity and temperature. Frictional heating is the most important factor that influences the maximum displacement of the isolation system and floor spectral demands if the static axial pressure is high. Isolation system displacements are not significantly affected by considerations of the influence of axial pressure and velocity on the coefficient of friction. Copyright © 2014 John Wiley & Sons, Ltd.     

Impact of the equivalent center of mass separating from the sliding surface on the isolation performance of friction pendulum bearings

A new equivalent center of mass model of FPBs(friction pendulum bearings) is introduced, and based on this model, coefficient j of the equivalent center of mass separating from the sliding surface is defined. It is thought in theory that j has a significant impact on the isolation parameter of FPBs, since the equivalent post-yielding stiffness and friction coefficients are not simply determined by sliding radius and sliding friction pairs. The results of numerical simulation analysis using ABAQUS conducted on two groups of FPBs support this viewpoint. For FPBs with the same sliding radius and sliding friction pairs, the FPB modules of structural analysis software such as ETABS could only distinguish the equivalent transformation using j one by one. The seismic response data obtained in a base isolation calculation example of FPBs are very different, which reveals that j's impact on the isolation effectiveness of FPBs cannot be ignored. The introduction of j will help improve the classical structural theory of FPBs and the weak points of structural analysis software based on this theory, which is important in achieving more accurate analyses in structural design.     

Seismic performance of cable-sliding friction bearing system for isolated bridges

During past strong earthquakes, highway bridges have sustained severe damage or even collapse due to excessive displacements and/or very large lateral forces. For commonly used isolation bearings with a pure friction sliding surface, seismic forces may be reduced but displacements are often unconstrained. In this paper, an alternative seismic bearing system, called the cable-sliding friction bearing system, is developed by integrating seismic isolation devices with displacement restrainers consisting of cables attached to the upper and lower plates of the bearing. Restoring forces are provided to limit the displacements of the sliding component. Design parameters including the length and stiffness of the cables, friction coefficient, strength of the shear bolt in a fixed-type bearing, and movements under earthquake excitations are discussed. Laboratory testing of a prototype bearing subjected to vertical loads and quasi-static cyclic lateral loads, and corresponding numerical finite element simulation analysis, were carried out. It is shown that the numerical simulation shows good agreement with the experimental force-displacement hysteretic response, indicating the viability of the new bearing system. In addition, practical application of this bearing system to a multi-span bridge in China and its design advantages are discussed.     

A model of triple friction pendulum bearing for general geometric and frictional parameters

Current models describing the behavior for the triple friction pendulum (TFP) bearing are based on the assumption that the resultant force of the contact pressure acts at the center of each sliding surface. Accordingly, these models only rely on equilibrium in the horizontal direction to arrive at the equations describing its behavior. This is sufficient for most practical applications where certain constraints on the friction coefficient values apply as a direct consequence of equilibrium. This paper presents a revised model of behavior of the TFP bearing in which no assumptions are made on the location of the resultant forces at each sliding surface and no constraints on the values of the coefficient of friction are required, provided that all sliding surfaces are in full contact. To accomplish this, the number of degrees of freedom describing the behavior of the bearing is increased to include the location of the resultant force at each sliding surface and equations of moment equilibrium are introduced to relate these degrees of freedom to forces. Moreover, the inertia effects of each of the moving parts of the bearing are accounted for in the derivation of the equations describing its behavior. The model explicitly calculates the motion of each of the components of friction pendulum bearings so that any dependence of the coefficient of friction on the sliding velocity and temperature can be explicitly accounted for and calculations of heat flux and temperature increase at each sliding surface can be made. This paper presents (a) the development of the revised TFP bearing model, (b) the analytic solution for the force–displacement relations of two configurations of the TFP bearing, (c) a model that incorporates inertia effects of the TFP bearing components and other effects that are useful in advanced response history analysis, and (d) examples of implementation of the features of the presented model. Copyright © 2016 John Wiley & Sons, Ltd.     

竖向地震动对滑动摩擦隔震桥梁结构地震反应的影响

利用接触摩擦单元建立了滑动摩擦隔震桥梁支座在竖向地震动作用下的有限元模型,通过算例讨论了竖向地震动对不同支座摩擦系数和不同刚度(墩径)滑动摩擦隔震桥梁地震反应的影响,初步探讨了竖向地震动的激励方向对分析结果的影响,分析结果表明,竖向地震动对滑动摩擦隔震桥梁结构的地震反应有较大的影响,在竖向地震动较为明显地区的滑动摩擦隔震桥梁结构设计时,应予以考虑。     

板式橡胶支座对斜交连续梁桥地震反应的影响

为充分了解板式橡胶支座对斜交连续梁桥地震反应的影响,利用OpenSees软件建立简化的斜交桥计算模型进行时程分析,研究板式橡胶支座摩擦滑移效应,以及支座动摩擦系数、剪切刚度、局部脱空等参数对斜交桥地震反应的影响。结果表明:板式橡胶支座考虑摩擦滑移后,不仅桥面位移和转角显著增大,而且出现残余位移和残余转角;随着支座剪切刚度的增大,桥面位移和转角均明显减小;随着桥墩处支座动摩擦系数的增大,桥面位移、转角均呈增长趋势,然而桥台处支座动摩擦系数的影响与之相反;桥墩处局部支座脱空对斜交桥的影响明显大于桥台支座。     

Housner模型在隔震储罐计算中的适用性研究

隔震储罐的抗震性能分析中,底部剪力和隔振层位移是两个重要指标。Housner模型是储罐抗震设计中常用的液体简化模型,其在计算储罐底部剪力时有良好的准确性,并被广泛验证,但是对于隔振层变形的计算效果鲜有研究。运用实时子结构试验方法,对四条地震激励下的不同摩擦系数的摩擦摆隔震储罐进行了试验研究,并通过Housner模型代替试验储罐对各个工况进行了仿真。分析结果表明:地震荷载作用下,Housner模型用于储罐底部剪力计算时准确性较高,与实验结果相比平均误差仅为11%。但是在隔振层滑移位移的计算中与实验结果差距较大,平均误差为22%,最大误差超过30%。     

考虑支座摩擦滑移及结构碰撞的非规则人字形桥梁地震响应分析

针对非规则人字形桥梁在地震作用下灾变严重的问题,以一座非规则人字形桥梁为研究对象,建立其空间分析模型,研究综合考虑支座摩擦滑移、结构碰撞对非规则人字形桥梁地震响应的影响。结果表明:邻梁间的碰撞作用可使得桥梁墩顶位移及内力相比不考虑时有所减小,但同时也使梁体产生了较大的加速度脉冲效应;当考虑支座摩擦滑移和结构碰撞时,固定墩墩顶位移和邻梁相对位移峰值有一定程度增大,然而对梁体加速度脉冲效应结果影响并无统一规律;纵向地震波作用下,非规则人字形桥梁不仅存在顺桥向的碰撞,横桥向的碰撞响应也不容忽视。非规则人字形桥梁进行抗震设计计算时应选取符合实际情况的计算模型,考虑支座摩擦滑移及结构间的碰撞。     

柱端设置盖板式滑移摩擦节点H型钢柱抗震稳定性研究

基于损伤控制理念,提出了一种盖板式滑移摩擦柱端节点,该节点利用滑移摩擦代替材料屈服耗能,达到避免构件损伤的目的。为研究在柱端设置该节点H型钢柱的抗震稳定性能,设计并制作2个1/2缩尺的H型钢柱试件:一个试件为普通H型钢柱;另一个试件为柱端设置盖板式滑移摩擦节点H型钢柱,并进行低周往复加载试验。试验结果分析表明:在低周往复加载作用下,柱端设置盖板式滑移摩擦节点的构件,仅翼缘盖板发生塑性变形及黄铜摩擦板出现磨损,钢柱未发生损伤;其极限承载力相较于普通H型钢柱低10%;滞回曲线饱满,刚度与耗能能力与普通H型钢柱相差不大,表现出良好的抗震性能。有限元模拟结果与试验结果基本吻合,并通过有限元模拟分析盖板厚度对设置盖板式滑移摩擦节点H型钢柱受力性能的影响,研究结果表明:合理设置盖板厚度,在提高柱承载力的同时,保证了节点的摩擦耗能,使得钢柱得到有效保护,达到了预期的损伤控制目标。