Resilience-based retrofitting of existing urban RC-frame buildings using seismic isolation

The improvement of the seismic resilience of existing reinforced-concrete(RC) frame buildings, which is essential for the seismic resilience of a city, has become a critical issue. Although seismic isolation is an effective method for improving the resilient performance of such buildings, target-oriented quantitative improvements of the resilient performance of these buildings have been reported rarely. To address this gap, the seismic resilience of two existing RC frame buildings located in a high seismic intensity region of China were assessed based on the Chinese Standard for Seismic Resilience Assessment of Buildings. The critical engineering demand parameters(EDPs) affecting the seismic resilience of such buildings were identified. Subsequently, the seismic resilience of buildings retrofitted with different isolation schemes(i.e., yield ratios) were evaluated and compared, with emphasis on the relationships among yield ratios, EDPs, and levels of seismic resilience. Accordingly, to achieve the highest level of seismic resilience with respect to the Chinese standard, a yield ratio of 3% was recommended and successfully applied to the target-oriented design for the seismic-resilience improvement of an existing RC frame building. The research outcome can provide an important reference for the resilience-based retrofitting of existing RC frame buildings using seismic isolation in urban cities.

A Design of High-precision High-Voltage Fiber-Optic Analog Signal Isolation Converter

This paper introduces a design of high-precision high-voltage fiber-optic analog sig-nal isolation converter based on the technology of Voltage-to-Frequency (V/F) and Frequency-to-Voltage (F/V) conversion. It describes the principle, system configuration and hardware design.

Optimization Design of Vibration Characteristics of Ship Composite Brace with Rigid Vibration Isolation Mass

In considering the theory of structural dynamic optimization design, a design method of the structural style of ship composite brace with rigid vibration isolation mass was studied. Two kinds of structural dynamic optimization formulations minimizing the vibration acceleration of the non-pressure hull on the restraining condition of the gross weight of the ship cabin were established: 1) dynamic optimization of the sectional dimensions of the rigid vibration isolation mass in the composite brace; 2) dynamic optimization of the arranging position of the rigid vibration isolation mass. Through the optimization results, sectional dimensions and the arranging position of the rigid vibration isolation mass with better performance in reducing vibration were gained, and some reference was provided for practical engineering designs as well as enrichment of the design method of a novel ship vibration-isolation brace.

Optimal design for rubber concrete layered periodic foundations based on the analytical approximations of band gaps and mapping relations

The seismic performance of rubber concrete-layered periodic foundations are significantly influenced by their design,in which the band gaps play a paramount role.Aiming at providing better designs for these foundations,this study first proposes and validates the analytical formulas to approximate the bounds of the first few band gaps.In addition,the mapping relations linking the frequencies of different band gaps are presented.Furthermore,an optimal design method for these foundations is developed,which is validated through an engineering example.It is demonstrated that ensuring the superstructure’s resonance zones are completely covered by the corresponding periodic foundation’s band gaps can achieve satisfactory vibration attenuation effects,which is a good strategy for the design of rubber concrete layered periodic foundations.

Vibration Isolation Characteristics of Impedance-balanced Ship Equipment Foundation under Unbalanced Excitation

A new type of impedance-balanced ship equipment foundation structure based on the principle of impedance balancing using a“discontinuous panel-vibration isolation liquid layer-foundation structure”is proposed to solve the problem of poor low-frequency vibration isolation of the foundation under unbalanced excitation of shipboard equipment.Based on the finite element method,the influence of characteristic parameters of the foundation panel structure on its vibration reduction characteristics under unbalanced excitation is explored.The results show that the vibration isolation level of the impedance-balanced foundation is 10 dB higher than the traditional foundation in the low-frequency band of 10-500 Hz when subjected to combined excitation of concentrated force and moment.Increasing the thickness of the impedance-balanced foundation panel can enhance the isolation effect.Increasing the number of sub-panels can effectively reduce the vibration response of the foundation panel and enhance the isolation performance of the foundation.The connection stiffness between sub-panels has a small effect on the isolation performance of the foundation.

The Behavior of Multi-Story Buildings Seismically Isolated System Hybrid Isolation (Friction, Rubber and with the Addition of Rotational Friction Dampers)

Increasing buildings’ resistance to earthquake forces is not always a desirable solution especially for the building contents that are irreplaceable or simply more valuable than the actual primary structure (e.g. museums, data storage Centre’s, etc.). Base isolation and seismic dampers can be employed to minimize inter-story drifts and floor accelerations via specially designed isolation and dampers system at the structural base, or at higher levels of the superstructure. In this research, we’ll examine the response of buildings isolated using isolation system hybrid consisting of Lead-Rubber Bearings (LRB), Flat Sliding Bearings (FSB), with the addition of Rotation Fiction Damper (FD) at the base, then compare the results with buildings that have traditional foundation, in terms of the (period, displacement and distribution shear force and height of the building). It conducts TIME HISTORY seismic analysis for some varying height buildings (eight, twelve, sixteen, and twenty stories), with help of SAP2000 using an earthquake acceleration-time history for (El- Centro). The results show that the use of insulation system Hybrid has had a significant impact on improving the performance of origin in terms of reducing displacements and base shear with in-creasing height of the building, but has had a negative impact on the drift, which leads to an in-crease in drift with the increased flexibility of the building.

Seismic Isolation of Reactor Assembly for a Fixed Base Accelerator Driven System Reactor Building

In the SILER （Seismic-Initiated events risk mitigation in LEad-cooled Reactors） Project, it is interesting to apply seismic isolation technology for the reactor assembly of the fixed base reactor building for ADS （Acceleration Driven System） heavy liquid reactor MYRRHA （Multipurpose Hybrid Research Reactor for High-Tech Application） which contains the most critical safety related components, such as reactor vessel, safe shutdown and control rod mechanisms, primary heat exchangers, primary pumps, spoliation target assembly and fuel assemblies, etc. The purpose of this paper is to investigate the possibility of an application of a partial seismic isolation to the safety critical components only, here, the reactor assembly. This paper presents the preliminary analysis results of the isolated reactor assembly and compares these with those of seismic isolated ADS reactor building. The analysis results show the reduction of the seismic acceleration response but the increase of the relative displacement for the reactor assembly. Some safety issues, especially, coolant＇s incapable covering the reactor core make difficult to apply for the partial seismic isolation of the ADS reactor assembly due to large relative displacement occurring the partial isolation system. Further study on the partial seismic isolation application of the critical safety components are also discussed.

Design optimization of a hexapod vibration isolation system for electro-optical payload

The electro-optical payloads on mobile platforms generally suffer undesirable vibrations generated by maneuvers and turbulence.These vibrations are in six degrees of freedom and cause line-of-sight jitters,resulting in image blurring and loss of tracking accuracy.In this paper,a Hexapod Vibration Isolation System(HVIS)is proposed and optimized to solve this problem.The optimization aims to centralize and minimize the natural frequencies of HVIS,for expanding the vibration isolation bandwidth and improving the vibration isolation in the higher frequency band.Considering that the design space for HVIS is limited and interfered with the frames of the mobile platform,a non-collision algorithm is proposed and applied in the optimization to obtain the feasible optimal design.The optimization result shows that the natural frequency bandwidth has been reduced by 42.9%,and the maximum natural frequency is reduced by 30.2%.The prototypes of initial and optimal designs are manufactured and tested.Both simulated and experimental results demonstrate the validity of the optimization,and the optimal design provides a maximum of 15 dB more isolation in rotation direction than the initial design.

Isolation and Preparative Purification for Ginkgolides A and B

In this paper a simple preparative method for isolation and purification of ginkgolides A and B was developed,As starting material,a commercially available standardized ginkgo extract (EGb761,containing 24% flavonoid and 6% terpene trilactones) was used,After a pretreatment step,optimized by the uniform design method ,the concentrated intermediate extract with high content of GA and gb(+90%) was separated into the individual terpenes by preparative liquid chromatography eluted with petroleum ether-ethylacetate,Analysis of products was carried out by means of HPLC-ELSD(evaporative light -scattering detector),The results show that ginkgolides A and B are obtained in higher yield and better purity.

Application Research of Genetic Algorithm on the Whole-Spacecraft Vibration Isolation System

The objective of the whole-spacecraft vibration isolation (WSVI) system is to reduce the launch-induced dynamic loads and the quality control cost of the satellite and its components, and to increase the launch reliability by insertion of isolators between the satellite and the launch vehicle. A niche hybrid genetic algorithm (NHGA) is proposed to optimize stiffness and damping of the isolators. Through the comparison of the frequency response analysis results, it shows that the optimized WSVI system more effectively reduces spacecraft axial / lateral response due to the broadband structure-born launch environment. At the same time, the case of the whole-spacecraft vibration isolation optimization design demonstrates the efficiency and validity of the genetic algorithm.

Optimizing Parameters of Rail-induced Vibration Isolation Trench Using Simplified FEM Approach

A simplified approach is proposed to reduce computational cost in conventional parametric optimization of open or in-filled trenches isolating rail-induced structural vibrations. In particular, it stands on an FEM-based hybrid optimization scheme consisting of multiple two-dimensional models and one global three-dimensional model. First, representative planar FE （finite element） models orthogonal to the rail-direction are identified. For each section, the sensitivity of the trench＇s design parameters, such as geometry and backfill materials, to its vibration screening effect is respectively evaluated. Second, a full trench along the rail-direction is determined according to the two-dimensional optimization result. The global performance of the optimal trench is simulated in the three-dimensional model and finally becomes a reference for practical design. By optimizing the design parameters of a case study project, the proposed approach has shown the capability of solving complex engineering problems at a minimum computational cost, therefore is applicable in determining design parameters of rail-induced vibration isolation trenches.

泸定地震中典型隔震建筑震害分析

为落实国务院744号令关于在“两区八类建筑”中推广使用隔震技术的要求,推动隔震技术的健康发展,对位于泸定地震震中的两栋隔震建筑的震害情况进行了调查。分析了某教学行政楼中隔震层的阻尼器及连接件、支墩震害原因,介绍了某宿舍楼的隔震支座震损情况,对两栋建筑隔离缝等构造处理的不合理导致震损的不足之处进行了全面、系统总结。提出了隔震建筑设计应全专业协调,避免过多设置隔离缝将建筑分割过于零碎;与阻尼器连接支墩需进行剪扭验算;穿越隔震层的设备管道的柔性连接应设置U形段预留变形长度,宽度较大的隔离缝应注意防掉落及通行需求的设计及构造等改进意见。并对隔震结构的施工,产品的检验、验收及建设单位责任提出了相关要求。

近远场地震下RC大跨轻柔拱桥减隔震支座方案优化

为探明不同地震动输入对某大跨轻柔拱桥减隔震的影响,通过非线性有限元模型分析近远场地震下桥梁结构的响应规律,得到大桥支座的优化布置方案.首先,基于模态分析,对比该桥与传统钢筋混凝土(RC)拱桥动力特性差异;其次,选取不同脉冲周期的近场地震动、近场无脉冲及远场长周期地震动记录;最后,研究近远场地震下拱桥的响应行为和损伤演化路径,得到优化桥梁的减隔震支座设计方案.研究结果表明:近场脉冲及远场长周期地震下的桥梁结构响应大于无脉冲地震响应;纵竖向地震下高墩柱剪力及弯矩包络曲线呈“S”形,墩身中部易形成塑性铰,高阶振型影响显著;桥梁纵桥向先于横向震损,损伤路径依次为矮柱、高墩柱及拱肋实心-空心截面段;摩擦摆支座减震效果最佳但位移较大,高阻尼支座方案在近场中长脉冲周期及远场长周期地震下仍会发生损伤,板式橡胶支座方案因无法保证支座同步滑移而不能形成准隔震体系;“高阻尼+摩擦摆”混合方案的支座位移小,拱肋及墩柱均处于弹性,是近断层大跨轻柔RC拱桥的优选减隔震方案.

基于时程分析法的中美隔震设计对比研究

介绍了中国《建筑隔震设计标准》(GB/T 51408—2021)(以下简称《隔标》)和美国Minimum design loads and associated criteria for buildings and other structures(ASCE 7-16)隔震设计的相关要求,并针对基于《建筑抗震设计规范》(GB 50011—2010)(2016年版)(以下简称《抗规》)设计的某9度区近场隔震结构,进行了两国规范的设计对比。按《抗规》设计的隔震结构,仍然能满足《隔标》的设计要求。ASCE 7-16对于隔震支座考虑了老化和环境、测试、制造等因素引起的性能参数变化,并按隔震支座的上限及下限属性进行了结构设计。基于相同地震概率水准(50年超越概率2%)的设计对比研究表明,ASCE 7-16的等效侧力法计算值高于《隔标》,按ASCE 7-16要求选择的地震波反应谱明显高于《隔标》,其时程分析结果也大于中国规范,对隔震支座的性能要求更高。

基于深度学习的隔震构造节点检测方法

为提高隔震构造节点的检测效率和效果并实现其自动化检测,按构造做法将隔震构造节点分为设置水平隔震缝构造节点、设置竖向隔震缝构造节点和管线设置柔性连接构造节点3类.选取设置水平隔震缝的隔震构造节点,根据其检测要求和缺陷特征,提出了一种基于深度学习的隔震构造节点检测方法.通过实地拍摄国内128个隔震工程的隔震构造节点图像,建立并标定了隔震构造节点数据集,将深度残差网络模型与迁移学习技术相结合,构建了隔震构造节点检测模型.结果表明,该模型在测试集上的识别准确率达到98.4%,F_(1)分值为0.984,可较好地提取水平隔震缝特征,准确判断隔震构造节点是否存在水平隔震缝缺陷,从而实现设置水平隔震缝构造节点的自动检测.

减隔震技术对9度近断层区框架结构抗震性能影响与经济性分析

为研究减隔震技术对9度近断层区框架结构抗震性能影响及其经济性,以某多层框架结构为研究对象,在保证结构力学指标为85%的规范限值的原则下,对其分别进行抗震、减震、隔震设计,采用ETABS软件建立结构的抗震、减震、隔震模型并对其进行近断层和非近断层地震动作用下的抗震性能对比分析,以及工程量和经济性分析。结果表明,各模型在近断层地震动下的反应大于非近断层地震动下的。在近断层罕遇地震下,相较于抗震模型,隔震模型最大层间位移角减小6898%,楼面峰值加速度减小7677%,楼层剪力减小8367%;相较于抗震、减震模型,隔震模型在近断层多遇地震和设防地震下的响应及填充墙破坏程度最小,隔震结构抗震性能最优。相较于抗震模型,减震、隔震模型造价分别降低857%、554%,所以减震设计的工程造价最低。

桥梁抗震设计关键内容与减震、隔震技术的应用

为避免因发生地震而出现的桥梁结构失稳、倒塌问题,该文针对桥梁工程的抗震设计进行详细分析,结合桥梁结构出现的震害,提出桥梁抗震设计的关键点、减隔震技术的运用对策,旨在以桥梁工程为例,对比减隔震技术相较于非减隔震技术在提升抗震性能、降低震害风险等方面起到重要作用。这一研究将为桥梁抗震设计,合理运用减隔震技术提供重要参考。

双向恢复力模型对基础隔震建筑风振响应的影响

为明确MSS、Casciati和Harvey and Gavin这3种常用双向恢复力模型计算基础隔震建筑风振响应的差异,采用3种模型模拟铅芯橡胶支座在水平单向和双向位移下的恢复力,对比试验或有限元结果的差异,采用3种模型对一算例在双向风荷载下隔震层位移、顶点位移和顶点加速度3个指标的差异进行了分析。研究表明:3种模型模拟铅芯橡胶支座在单向循环位移、方形和偏置方形位移下恢复力的趋势基本一致;而模拟圆形和偏置圆形位移时,MSS模型双向恢复力形状与有限元结果不同,不能较为准确地模拟支座双向耦合行为,Casciati模型误差稍小于Harvey and Gavin模型。Casciati模型和Harvey and Gavin模型计算风振响应基本一致;对于横风向响应均方根,3种模型差距不大;对于顺风向隔震层位移、顶点位移和顶点加速度均方根,MSS模型稍小,而对于顺、横风向隔震层位移峰值因子,MSS模型稍大;对于顺、横风向顶点加速度峰值因子和双向与单向模型顶点加速度最值比值随风速变化规律,MSS模型与其他模型差异较大。基于双向耦合效应模拟及风振响应指标的差异,建议采用Casciati模型考虑双向恢复力模型对基础隔震建筑风振响应的影响。

百年文物宏恩医院隔震和顶升一体化研究

城市更新过程中文物建筑作为历史留存多被赋予新的使命,但在修缮改造中抗震加固由于范围广对文物建筑保护影响很大。对于位于高烈度区或者抗震安全需求高的文物建筑,需要合理解决建筑保护和抗震安全之间的矛盾。宏恩医院是上海市文物保护建筑,建成至今一直作为医疗场所使用,属抗震重点设防类建筑,但原结构存在体型不规则、结构转换、抗震承载力严重不足等多项抗震不利情况。为此,在文物保护基础上,对文物建筑抗震性能目标的确立、抗震加固方案比选、软土地基上隔震布置及效果评估、结构顶升阶段的安全控制以及隔震和顶升施工的结合等多个关键技术进行介绍。通过隔震顶升一体化和性能化设计实现了文物建筑抗震安全和最小干预的保护要求,对文物建筑的可持续利用和抗震韧性具有借鉴意义。

混合基础隔震体系优化设计及性能

为解决基础隔震结构中隔震层位移需求过大的问题,提出了一种基础隔震结构(Base Isolated Structure,BIS)+串并联调谐质量阻尼器惯容器(Tuned Tandem Mass Damper-Inerter, TTMDI)的混合隔震体系。采用Bouc-Wen滞回模型模拟隔震层的非线性力-变形行为,基于随机等效线性化和模式搜索优化算法并考虑地震动模型,在频域内建立了BIS+TTMDI体系的优化设计框架。分别从鲁棒性、有效性、刚度和阻尼系数、冲程及对地震频率敏感性方面对BIS+TTMDI体系的性能进行评估,并与BIS+调谐质量阻尼器(Tuned Mass Damper, TMD)、串并联调谐质量阻尼器(TunedTandemMassDamper,TTMD)和调谐质量阻尼器惯容器(TunedMass Damper-Inerter, TMDI)进行比较。通过对近场地震动下某七层混合基础隔震结构(包括BIS+TTMDI和BIS+TMDI体系)的动力弹塑性分析,评价了其减/隔震性能。结果表明:BIS+TTMDI体系具有最好的减/隔震性能和强鲁棒性;而且在BIS+TTMDI体系中TTMDI的总阻尼需求不到BIS+TMDI体系中TMDI的一半,因而更为经济实用。