X形和三角形SMA板式阻尼器的阻尼力模型

本文利用形状记忆合金（Shape Memory Alloy，简称SMA）分段线性化本构关系，推导了X形和三角形SMA板式阻尼器的阻尼力滞回模型。首先，给出了SMA分段线性化本构关系。然后，根据经典力学理论推导建立了SMA板式阻尼器的阻尼力模型。最后，通过一个算例给出了SMA板式阻尼器的阻尼力滞回曲线，结果表明，其滞回曲线在T＞Af时为“小旗帜”形状；而且，在弹性加载、马氏体相变阶段和卸载至逆相变开始前的规律与钢板阻尼器的线性强化模型相同；逆相变开始后，横截面上应力分布发生间断，阻尼力曲线接近直线。     

基于BP网络本构模型的SMA拉索系统优化控制分析

通过试验测试了SMA材料的超弹性性能,以材性试验数据作为BP网络的训练样本,建立了SMA经遗传算法优化的BP网络本构模型。在MATLAB中直接调用该本构模型,利用改进的遗传算法,对一空间模型结构进行了SMA位置和数量的优化,并对最优布置方案进行了地震反应分析。结果表明,相比未优化的BP网络,优化后的BP网络本构模型与试验曲线吻合地更好,稳定性更高;BP网络本构模型调用简单,精度高,便于SMA控制系统的MATLAB仿真分析。改进的遗传算法能够保证遗传过程中SMA根数的不变,提高全局搜索的效率,获得更优的布置位置;经优化配置后的SMA控制系统可以更加有效发、地降低结构的地震反应,布置4根SMA拉索时,模型结构的层间位移之和即可减少44.51%。     

非线性土层地震反应分析的一种方法

本文利用作者给出的土的剪切动力本构关系的动态骨架曲线模型,结合显式差分数值逐步积分方法,给出了一种分析非线性土层地震反应的方法。反应计算中,地震效应视为基底剪切波垂直入射,且考虑了上部土层中能量向弹性基底辐射的效应。文章最后给出了本方法应用的一个算例,并给出了相应的等效线性化方法的计算结果。     

高层钢结构地震反应形状记忆合金拉索控制研究

本文通过形状记忆合金(SMA)材料的超弹性性能试验确定了SMA材料的各项参数和常温状态下的本构模型。对采用SMA拉索实施振动控制的20层钢结构的Benchmark模型的地震响应进行了时程分析。计算结果表明,实施SMA拉索控制后,层间相对位移可降低70％左右,且SMA材料很好的耗能作用有效地减少了地震能量向上部楼层的传递,对上部结构具有一定的隔振作用;顶层相对位移的控制效果达到51％;顶层加速度可降低43％;地震波强度和拉索初应变对拉索的被动控制效果影响较大。最后给出了拉索的安装位置与拉索的应变之间的关系曲线,建议了合理的布置方案。     

超弹性形状记忆合金螺旋弹簧恢复力的数值模拟

形状记忆合金(SMAs)在土木工程被动控制领域的研究近年来得到了极大的关注。研究人员已经提出了多种含有SMA丝的隔震器和阻尼器,大尺寸SMA超弹性螺旋弹簧是一种可输出较大位移的阻尼器。由于以往在结构防震减灾领域有关SMA螺旋弹簧力学性能的研究较少,因此在Liang和Rogers提出的SMA应力-应变本构模型的基础上,针对SMA螺旋弹簧恢复力特性建立了一种便于工程应用的新型宏观模型,并利用MATLAB程序进行了数值模拟以验证所提出模型的适用性和正确性。研究结果表明:SMA螺旋弹簧具有较好的复位和耗能能力;同时,根据该宏观模型得到的数值模拟结果与其他学者的试验研究结果吻合较好。总的来看,数值模拟方法可较准确描述超弹性弹簧的力学行为,且方便在现有常规结构软件中实现。     

非线性土木结构振动控制的逆系统方法

采用多变量非线性控制的逆系统理论,将多变量、非线性的复杂被控对象精确线性化成伪线性系统,对于该伪线性系统很容易基于线性系统理论设计综合最优控制器。克服了传统的非线性结构近似线性化控制方法不够精确的缺点,实现了非线性结构的动态精确线性化控制。给出了一个仿真实例,将其控制效果与一般的线性和近似线性化最优控制作了比较,达到同样控制效果时本方法所需控制力显著减小。     

SMA弹簧-摩擦支座基础隔震体系的地震响应分析

大尺寸超弹性形状记忆合金(Shape Memory Alloy,简称SMA)螺旋弹簧是一种可用于结构减振控制的阻尼器。然而,迄今为止这种超弹性阻尼器在土木工程结构隔震领域的研究较少。本文提出了一种SMA弹簧-摩擦支座(SMA Spring-Friction Bearing,简称SFB)并研究了其隔震性能。首先,在考虑材料内部相变过程的SMA本构关系模型的基础上,针对超弹性SMA弹簧的恢复力性能建立了一种便于工程应用的新的宏观现象模型。随后,推导了SFB隔震结构体系运动方程,利用MATLAB程序进行了结构地震响应的数值模拟。最后,将SFB隔震体系的地震响应与具有相同结构参数的纯摩擦支座(Pure Friction Bearing,简称PFB)隔震体系和摩擦摆(Friction Pendulum System,简称FPS)隔震体系的地震响应进行了对比分析。研究结果表明,SFB对上部结构具有良好的加速度减振效果,同时,该支座较其它两种滑动支座在降低隔震层位移峰值响应和抑制隔震支座残余位移两方面具有明显的优势。     

修正Matasovic本构模型在ABAQUS软件中的实现

Hashash等(2001)提出了土体的剪切模量和阻尼特性与土层深度相关的修正Matasovic(1993)黏弹性本构模型,本文基于ABAQUS/standard软件的子程序开发平台,编制了该修正Matasovic本构模型的子程序模块。以美国密西西比湾深厚场地为研究对象,选取Loma Prieta和Northridge地震动加速度记录作为基岩输入地震动,通过ABAQUS软件的二维场地非线性地震反应分析,给出了该深厚场地的地表加速度时程、反应谱,并与国际专业软件DEEPSOIL的一维场地非线性反应分析结果作了对比,发现两者的结果差别不大。这表明:采用基于ABAQUS软件开发的修正Matasovic土体黏弹性本构模型进行场地非线性地震反应分析,是可行的。目前工程上广泛使用的等效线性化方法存在一些不足之处,本文方法可以为工程应用提供参考和比较。     

应用形状记忆合金的桥梁结构振动控制研究及发展

简要介绍了形状记忆合金（SMA）材料的本构关系及其显著特性。总结了桥梁结构在地震和风振作用下的灾害，以及SMA驱动器和阻尼器在桥梁结构隔震及减震应用上的研究现状，展望了SMA在桥梁结构尤其是在大跨度斜拉桥和悬索桥结构抗震风振动控制中的应用前景，指出了基于SMA材料的桥梁结构振动控制研究中亟待解决的一些关键技术。     

SMA-压电半主动混合阻尼器减震控制分析

将形状记忆合金（Shape memory alloy,简称"SMA"）与压电摩擦阻尼器复合设计了一种半主动混合阻尼器,对SMA丝进行了材性试验,分析了循环圈数、加载速率和应变幅值对SMA丝力学性能的影响。基于试验数据,以速度方向和应变值作为神经元输入,建立了SMA的BP神经网络本构模型,并利用T-S模糊逻辑求解压电陶瓷驱动器输出电压,对1个2层的钢框架结构进行了无控、SMA被动控制和混合控制MATLAB仿真分析。结果表明:SMA的BP网络模型预测的应力误差大多集中在20 MPa以内,且误差较大点主要集中在加载的初始段和卸载的结束段等数值较小的点,BP神经网络能够较好地预测SMA丝的本构曲线。相比SMA被动控制,混合阻尼器可以更加有效地降低结构的动力反应。     

锥形形状记忆合金阻尼器性能分析与试验研究

本文对一种新型形状记忆合金阻尼器——锥形形状记忆合金阻尼器的性能进行了数值分析和试验研究。基于形状记忆合金的超弹性双线型本构模型,利用非线性有限元方法分析了锥形形状记忆合金阻尼器的滞回性能,并且用大型能用程序ANSYS进行了验证,得出锥形形状记忆合金阻尼器的滞回模型可简化为分段线性滞回模型,试验包括形状记忆合金丝的本构试验、疲劳试验阳阻尼器的性能试验．试验结果与数值分析结果基本吻合,形状记忆合金表现出良好的超弹性。     

A new isolation device using shape memory alloy and its application for long-span structures

The key points to consider in determining the effectiveness of using structural isolation with shape memory alloys (SMA) are the constitutive model, the SMA isolation device and the analysis method. In this paper, a simplifi ed constitutive model based on the classic theory of plasticity is proposed to simulate the behavior of the superelasticity of the SMA, in which the martensite volume fraction is considered as one of the state variables. Comparisons between simulation results and experimental results ar...     

框架结构SMA阻尼器被动控制模拟分析

介绍了形状记忆合金(SMA)阻尼器的性能,引入其本构关系,建立其热力学方程。针对所提出的阻尼器及相关参数选择,利用ANSYS进行框架结构中的被动控制模拟。将所得的未加与加入SMA阻尼器下顶层位移进行比较,发现SMA阻尼器可以很好地提高框架结构的抗震性能,并提出进一步研究的方法。     

Shaking table tests of steel frame with superelastic Cu–Al–Mn SMA tension braces

Shaking table tests are performed on a one‐bay one‐story steel frame with superelastic Cu–Al–Mn shape memory alloy (SMA) tension braces. The frame is subjected to a series of scaled ground motions recorded during the 1995 Kobe earthquake, Japan. The test results demonstrate that the SMA braces are effective to prevent residual deformations and pinching. It is also shown that the time history responses observed from the shaking table tests agree well with the numerical predictions using a rate‐independent piecewise‐linear constitutive model calibrated to the quasi‐static component tests of the SMA braces. This suggests that the loading rate dependence of Cu–Al–Mn SMAs as well as the modeling error due to the piecewise linear approximation can be neglected in capturing the global response of the steel frame. Numerical simulations under a suite of near‐fault ground motion records are further performed using the calibrated analytical models to demonstrate the effectiveness of the SMA braces when the variability of near‐fault ground motions is taken into account. A stopper, or a deformation restraining device, is also proposed to prevent premature fracture of SMA bars in unexpectedly large ground motions while keeping the self‐centering capability in moderate to large ground motions. The effectiveness of the stopper is also demonstrated in the quasi‐static component and shaking table tests. Copyright © 2015 John Wiley & Sons, Ltd.     

新型自复位连梁阻尼器设计及其力学性能数值模拟研究

为改善高层建筑联肢剪力墙抗震性能,消除传统连梁阻尼器残余位移较大或等效阻尼比较小等问题,设计了一种兼具耗能和自复位功能的形状记忆合金粘弹性连梁阻尼器（Shape Memory Alloy Viscoelastic Coupling Beam Damper,SVCBD）,给出了新型连梁阻尼器的构造形式和工作原理。利用拉普拉斯变换得到的粘弹性材料粘性系数以及超弹性形状记忆合金（Shape Memory Alloy,SMA）本构模型,基于ABAQUS仿真平台建立了SVCBD精细有限元模型;对SVCBD滞回特性进行了模拟分析,并与普通粘弹性阻尼器进行了对比。考虑了SMA丝束初始预应力度、横截面总面积和粘弹性材料层剪切面积等参数对SVCBD滞回特性的影响。分析结果表明:与普通粘弹性连梁阻尼器（Viscoelastic Coupling Beam Damper,VCBD）相比,SVCBD滞回曲线更加饱满,耗能能力更强,残余位移减小,初始刚度也大大提高,具有很好的耗能和复位效果;SMA丝束初始预应力大小、横截面面积（即配置数量）和粘弹性材料层剪切面积均对SVCBD的耗能和复位能力具有明显的影响。     

一种新型SMA阻尼器的试验研究

在对NiTi形状记忆合金（SMA）的力学性能试验研究的基础上,设计了一种新型SMA阻尼器,根据形状记忆合金丝的超弹性分段线性恢复力模型建立了阻尼器的理论模型,并通过阻尼器的性能试验研究验证了理论模型的正确性,试验结果表明这种阻尼器具有较好的耗能能力。     

Modeling and cyclic behavior of segmental bridge column connected with shape memory alloy bars

This paper examines the quasi-static cyclic behavior,lateral strength and equivalent damping capacities of a system of post-tensioned segmental bridge columns tied with large diameter martensitic Shape Memory Alloy(SMA) link-bars.Moment-curvature constitutive relationships are formulated and analysis tools are developed for the PT column,including a modified four-spring model prepared for the SMA bars.The suggested system is exemplified using a column with an aspect ratio of 7.5 and twelve 36.5 mm diameter NiTi martensitic SMA bars.A post-tensioning force of 40% to 60% of the tendon yield strength is applied in order to obtain a self re-centering system,considering the residual stress of the martensitic SMA bars.The cyclic response results show that the lateral strength remains consistently around 10% of the total vertical load and the equivalent viscous damping ratios reach 10%-12% of critical.When large diameter NiTi superelastic SMA bars are incorporated into the column system,the cyclic response varies substantially.The creep behavior of the superelastic SMA bar is accounted for since it affects the re-centering capability of the column.Two examples are presented to emphasize the modeling sensitivities for these special bars and quantify their cyclic behavior effects within the column assembly.     

Retrofit of non-seismically designed beam-column joints by post-tensioned superelastic shape memory alloy bars

A series of tests on three full-scale substandard exterior beam-column joints were performed to investigate the efficiency of the proposed retrofit configuration, which is the use of externally applied post-tensioned shape memory alloy (SMA) bars. A major group of structural deficiencies resulting from lack of shear reinforcement in the joint, use of low strength concrete and plain round bars were taken into account in the construction of test specimens. While the reference specimen represents the as-built subassembly, the other two were retrofitted by the post-tensioned SMA and steel bars to compare the contribution of superelastic and conventional material on the response. The specimens were exposed to quasi-static cyclic loading up to 8% drift ratio to simulate an intensive level of seismic hazard. The reference specimen underwent a brittle shear failure as excessive cracks mostly concentrated in the joint panel while there was almost no damage in the rest of the RC components. A joint failure with enhanced response quantities was observed in the specimen retrofitted by post-tensioned steel bars. The specimen incorporating the retrofit solution via post-tensioned SMA bars was capable of performing an adequate performance and promoting minimization of the damage in the joint panel, which results in more ductile behavior. The hysteretic response of the SMA retrofitted specimen was validated with a refined numerical model in ATENA Science software. Experimentally observed response was also verified by an analytical model based on fracture mechanics considering the nonlinear behavior of plain concrete under tension. Due to inherent uncertainties in material constitutive laws, the analytical model was evolved to a stochastic level to propose a more advanced model for estimating the capacity of the reference and retrofitted joint. It is found that the experimental results were within the prominent range of Probability Density Functions (i.e. mean ± 1 SD) of the estimated joint tensile stress especially for the shear damaged specimens.     

一种新型变形可恢复SMA阻尼器力学性能的研究

利用形状记忆合金（Shape Memory Alloy,简称"SMA"）丝材的超弹性与复位弹簧特性,开发出一种新型变形可恢复SMA阻尼器,以增强其变形可恢复的能力。同时,为了解决SMA丝材在实际工程中锚固难的问题,提出了一种新型可调节夹具,不仅解决了SMA丝材的不易锚固问题,而且增强了调节预应变的能力。对所提出的新型SMA阻尼器进行了循环加载试验研究和数值仿真分析,探讨不同加载频率及位移幅值对其力学性能的影响,建立了恢复力模型。结果表明:新型SMA阻尼器在循环荷载作用下滞回性能稳定,具有良好的耗能性能;内置弹簧对新型SMA阻尼器变形可恢复能力有较大帮助。基于所建立恢复力模型的数值模拟结果与试验结果符合情况很好,验证了阻尼器恢复力力模型的正确性。