Optimization of seismic isolation systems via harmony search

In this article, the optimization of isolation system parameters via the harmony search (HS) optimization method is proposed for seismically isolated buildings subjected to both near-fault and far-fault earthquakes. To obtain optimum values of isolation system parameters, an optimization program was developed in Matlab/Simulink employing the HS algorithm. The objective was to obtain a set of isolation system parameters within a defined range that minimizes the acceleration response of a seismically isolated structure subjected to various earthquakes without exceeding a peak isolation system displacement limit. Several cases were investigated for different isolation system damping ratios and peak displacement limitations of seismic isolation devices. Time history analyses were repeated for the neighbouring parameters of optimum values and the results proved that the parameters determined via HS were true optima. The performance of the optimum isolation system was tested under a second set of earthquakes that was different from the first set used in the optimization process. The proposed optimization approach is applicable to linear isolation systems. Isolation systems composed of isolation elements that are inherently nonlinear are the subject of a future study. Investigation of the optimum isolation system parameters has been considered in parametric studies. However, obtaining the best performance of a seismic isolation system requires a true optimization by taking the possibility of both near-fault and far-fault earthquakes into account. HS optimization is proposed here as a viable solution to this problem.     

新型自适应变刚度隔震装置的力学模型和地震响应分析

基于负刚度系统的力学性能特点,研发了自适应变刚度隔震装置.基于该装置的组成构造和变形机理,提出了其理论力学模型,给出了装置简化的三阶段变刚度模型.对自适应变刚度装置进行的竖向压缩拟静力试验结果表明,理论力学模型与试验力学模型的三阶段刚度基本一致,可有效模拟装置的变刚度力学特性.通过自适应变刚度装置与铅芯橡胶支座组合,给...     

混合基础隔震耗能结构基于Clough-Penzien谱的地震动响应的简明解析解

在基础隔震层设置侧向黏弹性阻尼器组成混合基础隔震体系,可有效降低基础隔震结构过大的侧移,然而此类结构基于Clough-Penzien谱(C-P谱)的随机地震动响应解法较为复杂,提出了一种简明解析法.首先利用滤波方程,将混合基础隔震耗能结构基于C-P谱的地震动精确的转化为基于白噪声激励的地震动;其次运用复模态法获得耗能结...     

柔性基础混合隔振系统建模与控制研究

实际的混合隔振系统一般由刚体振源、弹性安装基础以及连接它们的隔振器、作动器构成,是一个复杂的具有刚柔耦合特性的无限维分布参数系统。为了兼顾系统建模的准确性和控制器设计的方便性,采用子结构模态综合法对柔性基础混合隔振系统进行了建模,并与ANSYS建立的有限元模型进行了对比,在验证了模型有效性的基础上,基于修正的独立模态控制算法对混合隔振系统进行了控制设计和仿真分析,结果表明设计的混合隔振系统能够有效地减小基础的振动响应,且隔振效果优于被动隔振系统。     

新型钢滚轴及混合隔震结构地震模拟振动台试验研究

针对一种新型钢滚轴隔震支座进行研究,分别设计制作了一组钢滚轴隔震支座和一组摩擦摆隔震支座,并完成了某两层钢框架的固结、纯滚轴隔震、滚轴+MR被动阻尼器混合隔震和摩擦摆隔震模型的振动台试验。研究了各模型在地震加速度峰值为0.10 g、0.20 g的3条地震波作用下的结构响应,试验结果表明:新型钢滚轴隔震支座的隔震效果优于摩擦摆隔震支座,纯滚轴隔震模型和滚轴+MR被动阻尼器的混合隔震模型均可降低结构加速度反应56.1%～80.8%,且合理的优化混合阻尼隔震体系的阻尼值可使隔震效果更佳。同时,采用MR阻尼器的混合隔震模型较纯滚轴隔震模型可降低隔震层位移反应58.7%～87.4%,且随着阻尼值的增大其控制效果更好。因此,将新型钢滚轴隔震支座与阻尼装置配套使用的方法有效可行,在充分发挥滚轴隔震支座隔震效果的同时避免了结构隔震层位移过大的问题。     

复杂隔振结构激励下弹性基础振动及声辐射分析

针对隔振结构-弹性基础耦合结构向外声辐射问题,本文采用刚体理论及改进的傅里叶级数方法建立以任意边界弹性板为基础的双层隔振耦合结构数学模型。采用瑞利-里兹方法得到整个耦合结构的强迫振动响应,继而通过提取表面振速分布计算基础弹性板向外的辐射声功率。结合隔振结构的布置情况,以隔振器安装点的振动作为表征,探讨了耦合结构振动模态与基础板声辐射模态之间的耦合对应关系。最后计算并分析了基础边界条件对基础板向外辐射声功率的影响。     

结构抗震试验方法综述

反力梁是土木工程试验中的主要反力装置。当反力梁与试件的刚度比较小时,反力梁产生的变形与试件相比不可忽略。这种情况下,会对试验结果产生较大影响,特别是对拟动力和混合试验需要位移在线更新的试验影响更大。然而,关于反力梁变形的影响和补偿方法鲜有详细报道。为此,该文通过理论分析讨论了反力梁变形对抗震试验各参数的影响规律,建立了加载过程中对反力梁变形的在线补偿方法,并通过试验进行了验证。     

基于行车安全性的高铁桥梁横桥向减隔震体系研究

针对目前最常用的32 m跨径高铁简支梁桥,同时考虑对行车安全不利的路桥过渡段和墩高改变处,对高铁桥梁的行车安全性能进行了评价;分析了铅芯橡胶支座、摩擦摆支座等常规减隔震方案在高铁桥梁中运用的可行性.分析结果表明,采用盆式橡胶支座的高铁桥梁在地震作用下轨道变形和轨道横向加速度较大,无法满足高速运行的列车的行车安全性要求;...     

民用爆破器材标准化发展的作用及趋势

本文阐述了民用爆破器材标准化的内涵,总结了民爆标准化的发展历程和取得的成绩,归纳了民爆标准化七个方面的重要作用及相应的效果,论述了民爆标准化发展的趋势和要求。     

A three-dimensional animation system for seismic response of multistory structures

A three-dimensional animation system has been developed for visualizing the dynamic response of multistory structures subjected to earthquake excitations, using the IRIX operating system and implemented in Graphics Library (GL) Windows and ANSI C programming language. The animation system includes three-dimensional multistory frames with flexible floors. The input can be any accelerogram data (ground acceleration record) due to any real or artificial earthquake. The user of the system can select the input parameters of the structure, such as the number of bays, stories, bay width, story height, etc., and view their effect on the dynamic behavior of the structure. Sample outputs are presented for two irregular high-rise building structures. The graphics interface is linked to the dynamic analysis program. It computes the required displacements to be inputted back into the graphics interface which plots the deflected profile of the structure dynamically. © 1997 John Wiley & Sons, Inc. Int J Imaging Syst Technol, 8, 313–321, 1997     

倾斜旋转型三维隔震装置的力学模型和竖向性能试验研究

基于铅芯橡胶隔震支座的变形及耗能力学性能特点,设计开发出一种新型的倾斜旋转型三维隔震装置,给出了三维隔震装置的组成构造和力学性能设计方法,提出了三维隔震装置的变形机理,推导了三维隔震装置的刚度和阻尼的理论计算公式。设计了倾斜旋转型三维支座的模型支座系统,并完成了竖向压缩力学性能试验。试验结果表明该倾斜旋转型三维隔震装置构造合理、传力机制明确,在竖向变形状态下具有良好的阻尼耗能性能;试验得到的支座刚度和理论计算刚度一致性较好。     

社区地震安全韧性评估系统及应用示范

高烈度地区重要建筑往往采用RC框架-剪力墙结构体系,采用隔震技术设计该类建筑,满足《建设工程抗震管理条例》中规定的设防地震下正常使用要求,甚至满足罕遇地震下的高韧性目标需求,成为了该类结构设计的重点难题。该研究以一8度区的RC框架-剪力墙工程为例,对该结构的抗震方案展开了设防和罕遇地震下的地震韧性评价。在此基础上,针对隔震结构提出了3种上部结构设计理念,并设计了3个隔震案例,进行了设防和罕遇地震下的韧性评价。分析结果表明：传统抗震结构在设防地震下无法满足正常使用需求,抗震韧性等级仅为一星;按降一度贴限设计确定隔震上部结构截面且按降一度确定上部结构配筋时,设防地震下需3.1 d的修复时间才能恢复正常使用功能,罕遇地震下的抗震韧性等级为二星;按降半度贴限设计确定上部结构截面,且按降一度确定上部结构配筋时,建筑功能可基本不中断,满足正常使用需求,但罕遇地震下的抗震韧性等级仍为二星;按不降度贴限设计确定上部结构截面且按降一度确定上部结构配筋时,建筑功能完全不中断,满足正常使用要求,罕遇地震下可达到韧性三星。研究的相关成果可为高烈度地区RC框架-剪力墙结构的隔震韧性设计的深入研究提供参考。     

基于超弹性形状记忆合金的钢结构抗震研究进展

采用形状记忆合金(SMA)、粘弹性橡胶等材料的结构,其地震响应存在温度相关性,对其结构性能的评估应考虑温度影响和区域温度分布特性的不确定性。以第二代基于性能的地震工程评估框架为基础,该文提出一种考虑区域温度分布特性的温度相关型结构地震风险评估方法。该方法将传统地震易损性扩展为地震动强度-温度联合易损性,在此基础上得到包含温度分布信息的修正区域易损性,并用于评估结构地震风险。基于该方法,该文以9层SMA支撑钢框架结构作为分析对象,研究温度对结构性能的影响。选取北京和文昌为案例地区,给出其区域温度分布特性描述,并计算对象结构的地震风险曲线。结果表明：环境温度降低将影响结构变形分布。同时,结构在低温下更易发生倒塌。相对于位于文昌和设计基准温度下的对象结构,位于北京的对象结构具有更高的倒塌风险。所提出的方法能够量化评估不同地区温度相关型结构的地震风险。     

Optimal design base shear forces for reinforced concrete buildings considering seismic reliability and life-cycle costs

The objective of this study is to propose a novel estimation procedure for optimal design base shear forces for reinforced concrete (RC) buildings while considering the seismic reliability and life-cycle costs (LCCs) incurred by life-cycle earthquake events. By simulating life-cycle earthquake events within a specified period and using nonlinear dynamic analysis, including earthquake occurrences and their peak ground accelerations (PGAs), this study also derives the damage states of an RC building considering the effect of the cumulative damage. Additionally, besides life-cycle earthquake events, a simplified model is developed to modify the structural properties of a structure without seismic repair after earthquakes. Given the uncertainty of the occurrence time and PGAs of earthquake events, the seismic reliability, and expected current values of LCCs are calculated using Monte Carlo simulation. Although the case study addresses only an RC building with five stories in Taipei, optimal design base shear forces for low-rise RC buildings calculated via the same procedure can be derived and utilized when making decisions on the seismic level of a building based on safety and economic considerations. Therefore, the proposed method can help both owners and investors to identify LCCs of RC buildings due to seismic structural damage within a specified service life.     

土层地基上建筑结构混合控制的减震效率

研究土 -结构相互作用对结构混合控制减震效能的影响。首先建立了土层地基上结构混合控制的运动方程 ,通过不同输入地震波、不同土层剪切波速、不同结构参数等条件下的数值分析 ,讨论了桩基础对结构混合控制减震效率的影响规律。数值结果表明 :对于土 -结构相互作用体系 ,采用混合控制的减震效率明显要强于单一的 TL D的减震效率 ;在土层较为坚硬的情况下 ,混合控制仍具有较高减震效能 ;随着土层变软 ,土 -结构相互作用减小结构地震反应的效应趋于明显 ,混合控制的减震效率明显降低 ,因此 ,对软土地基上的结构实施混合控制时 ,必须先要正确分析土 -结构体系的地震反应。     

Probabilistic model for fatigue crack growth and fracture of welded joints in civil engineering structures

This paper presents a probabilistic assessment model for linear elastic fracture mechanics (LEFM). The model allows the determination of the failure probability of a structure subjected to fatigue loading. The distributions of the random variables for civil engineering structures are provided, and the relative importance of these random variables is determined. An example of a bridge detail is provided in order to show the application of the model. Partial factors are derived for the case of fatigue of welded joints in civil engineering structures. The failure probability appears to be relatively insensitive to the failure criterion (attainment of a through-thickness crack or fracture) when considering the total fatigue life.     

民用工程的噪声污染与隔声技术的应用

民用工程的噪声污染给职工与居民的安全健康带来影响。分析这类民用工程噪声污染的来源与特点,着重论述了运用综合声学措施降低噪声传播的方法,并介绍相关的设计。其中,隔声技术以效果明显、取材方便、使用灵活而得到广泛应用,详细叙述了该技术在民用工程噪声控制中的几种应用。     

A selective strategy for shakedown analysis of engineering structures

Determining the load‐bearing capacity of engineering structures is essential for their design. In the case of varying thermo‐mechanical loading beyond the elastic limit, the statical shakedown analysis constitutes a particularly suitable tool for this. The application of the statical shakedown theorem, however, leads to a nonlinear convex optimization problem, which is typically characterized by large numbers of variables and constraints. In the present work, this optimization problem is solved by a primal–dual interior‐point algorithm, which shows a remarkable performance due to its problem‐tailored formulation. Nevertheless, the solution procedure remains still a demanding task from computational point of view. Thus, the aim of this paper is to tackle the task of solving large‐scale problems by use of a new so‐called selective algorithm. This algorithm detects automatically the plastically most affected zones within the structure, which have the highest influence on the solution. The entire system is then reduced to a substructure consisting of these zones, based upon which a new optimization problem can be set up, which is solved with significantly less effort. Consequently, the running time decreases drastically, as is shown by application to numerical examples from the field of power plant engineering. Copyright © 2013 John Wiley & Sons, Ltd.     

精密可控震源隔振系统参数优化设计

针对精密可控震源压重在激振作业中振幅过大会导致震源下传能量减小及信噪比降低,而隔振系统对震源压重的振动情况有较大影响,对隔振系统参数进行了优化设计。结合机械系统动力学及半无限空间理论建立震源振动动力学模型,采用压重振幅放大系数作为压重振动幅值大小的评价指标,分析压重振幅与隔震系统参数之间的关系,并利用MATLAB软件分别分析隔振系统刚度、阻尼比等关键参数对它的影响;分析发现隔振系统刚度与阻尼比在激振过程中对压重振幅有着较大的影响,不合理的参数设计会使压重剧烈振动甚至发生共振。在此基础上,基于坐标轮换法设计了相应的优化算法,并得到了扫描频宽范围内不同压重质量下隔振系统刚度和阻尼比的最优参数组合。研究结果表明：优化后的精密可控震源隔振系统压重振动幅值在整个扫描频宽内波动显著减小,振幅最大值较优化前减小了75%。研究结果为精密可控震源隔振系统设计提供了参考和指导,为提升震源能量传递率及信噪比提供了一种新思路。     

面向创新设计的专题知识库构建与应用

产品创新设计需要大量知识的支持,针对产品设计过程对于产品专题知识的需求,提出了一种面向产品专题设计的知识库构建及应用方法.通过分析专题知识在设计过程中的作用,建立了专题知识的结构与表示方法,设计了一种混合式知识检索模型,并在此基础上开发了面向特定产品的专题知识库原型系统,从而有效辅助设计人员开展产品创新设计.以数控压力机离合器为例验证了该方法和系统的有效性.