Numerical investigation on seismic performance of a shallow buried underground structure with isolation devices

A design procedure for improving the seismic performance of unequal-span underground structures by installing isolation devices at the top end of columns is proposed based on the seismic failure mode of frame-type underground structures and the design concept of critical support columns.A two-dimensional finite element model(FEM)for a soil-underground structure with an unequal-span interaction system was established to shed light on the effects of a complex subway station with elastic sliding bearings(ESB)and lead rubber bearings(LRB)on seismic mitigation.It was found that the stiffness and internal force distribution of the underground structure changed remarkably with the installation of isolation devices at the top end of the columns.The constraints of the beam-column joints were significantly weakened,resulting in a decrease in the overall lateral stiffness and an increase in the structural lateral displacement.The introduction of the isolation device effectively reduces the internal force and seismic damage of the frame column;however,the tensile damage to the isolation structure,such as the roof,bottom plate,and sidewall,significantly increased compared to those of the non-isolation structure.Although the relative slip of the ESB remains within a controllable range under strong earthquake excitation as well as frame columns with stable vertical support and self-restoration functions,the LRB shows a better performance during seismic failure and better lateral displacement response of the unequal-span underground structure.The analysis results provide new ideas and references for promoting the application of seismic isolation technology in underground structures.

Seismic fragility of structures isolated by single concave sliding devices for different soil conditions

This study deals with the seismic fragility of elastic structural systems equipped with single concave sliding（friction pendulum system（FPS）） isolators considering different soil conditions. The behavior of these systems is analyzed by employing a two-degree-of-freedom model, whereas the FPS response is described by means of a velocity-dependent model. The uncertainty in the seismic inputs is taken into account by considering artificial seismic excitations modelled as timemodulated filtered Gaussian white noise random processes of different intensity within the power spectral density method. In particular, the filter parameters, which control the frequency content of the random excitations, are calibrated to describe stiff, medium and soft soil conditions. The sliding friction coefficient at large velocity is also considered as a random variable modelled through a uniform probability density function. Incremental dynamic analyses are developed in order to evaluate the probabilities of exceeding different limit states related to both the reinforced concrete（RC） superstructure and isolation level, defining the seismic fragility curves within an extensive parametric study carried out for different structural system properties and soil conditions. The abovementioned seismic fragility curves are useful to evaluate the seismic reliability of base-isolated elastic systems equipped with FPS and located in any site for any soil condition.

Control devices incorporated with shape memory alloy

Abstract： Shape Memory Alloy （SMA） is a type of material that offers some unique characteristics for use in devices for vibration control applications. Based on SMA＇s material properties, fottr types of control devices that incorporate NiTi SMA wires are introduced in this paper, which include three types of dampers （SMA damper, SMA-MR damper and SMA-friction damper） and one kind of isolation bearing （SMA-rubber bearing）. Mechanical models of these devices and their experimental verifications are presented. To investigate the control performance of these devices, the SMA-MR damper and SMA-rubber bearing are applied to structures. The results show that the control devices could be effective in reducing the seismic response of structures.

Research on Nonlinear Dynamic Characteristics ofStructures Supported on Slide-Limited Friction Base Isolation System

This paper presents a new type of base isolation system, i. e. , slide-limited friction (S-LF) base isolation system . Based on this system, the harmonic and subharmonic periodic response of S-LF subjected to harmonic motions is investigated by using Fourier-Galerkin-Newton (FGN) method with Flo-quet theory. The dynamic response of S-LF subjected to earthquake ground motions is calculated with a high order precision direct integration method, and the numerical results are presented in maximum acceleration response spectra of superstructure and maximum sliding displacement response spectrum form. The comparison of isolating effects of S-LF, pure-friction base isolation system (P-F) and resilient-friction base isolation system (R-FBI) shows that the isolating property of S-LF is superior to those of P-F and R-FBI. Finally, by analyzing an engineering example, it is observed that the distribution of the maximum shear between floors and absolute acceleration of S-LF to earthquake ground motion is very different from that of traditional structures.

Total ionizing dose effect in an input/output device for flash memory

Input/output devices for flash memory are exposed to gamma ray irradiation. Total ionizing dose has been shown great influence on characteristic degradation of transistors with different sizes. In this paper, we observed a larger increase of off-state leakage in the short channel device than in long one. However, a larger threshold voltage shift is observed for the narrow width device than for the wide one, which is well known as the radiation induced narrow channel effect. The radiation induced charge in the shallow trench isolation oxide influences the electric field of the narrow channel device. Also, the drain bias dependence of the off-state leakage after irradiation is observed, which is called the radiation enhanced drain induced barrier lowing effect. Finally, we found that substrate bias voltage can suppress the off-state leakage, while leading to more obvious hump effect.

隔震装置阻尼机构的参数设计与振动台试验

为了改善浮放物体隔震装置中阻尼力的施加方式,研制出一款阻尼机构。对其构造和工作机理进行阐述,推导出了它的力学特征表达式,并验证了分析模型的准确性。结合某文物隔震装置的目标性能,利用数值方法对阻尼机构的参数进行设计,并对比振动台试验。结果表明:该阻尼机构结构简单,性能稳定;经阻尼参数优化后的隔震装置在满足位移限值的情况下达到了设定的隔震目标;试验与数值分析结果相吻合,证明了阻尼机构参数设计的正确性,同时也检验了隔震装置的安装和运行质量。其中,试验与数值分析结果的吻合程度,尤其是位移时程曲线的吻合程度,可为浮放物体隔震装置的方案对比和质量评估提供思路。

新型万向球摆式隔震装置的设计与应用

针对浮放物体防震保护的迫切需求,研发了一款基于万向球的摆式隔震装置。首先介绍了它的构造特征与运行原理,并以某陈列佛塔为对象进行方案设计,利用有限元软件模拟万向球与圆盘间的接触关系,评估该装置的承载能力;然后通过试验验证了内部阻尼机构力学模型的准确性,采用时程分析法检验了该装置在8度极罕遇地震作用下的隔震效果,并与传统滑动摩擦摆的减震性能进行了对比。结果表明,该隔震装置不仅结构简单、性能可靠,而且具有摩擦系数低,起滑加速度阈值小,阻尼灵活可调的特点。装置中的点面接触具有一定的承载能力,能够满足设计需求。端部设置黏滞阻尼器的阻尼机构表现出明显的速度相关性,阻尼力会随速度的增大而增大。该装置隔震性能良好,在满足位移限值的情况下达到了设定的隔震目标,而且相比于传统型,在位移和加速度响应均需兼顾的情况下,通过合理调整阻尼机构的性能参数,该装置在各地震工况中能够取得更优的综合隔震效果。

曲线轨道式隔震装置的结构优化与应用研究

针对浮放物体的防震保护需求,研发出一款基于新型抗侧移组件的曲线轨道式隔震装置。阐述它的构造特点和运行机制,并依据结构原理制作模型,通过试验与理论对比来检验模型的运行质量进而验证方案的可行性。然后结合雨花阁内文物来设计样机,采用多条楼面波进行样机的振动台试验,测试其隔震效果。最后探讨建筑滤波效应对该类隔震装置设计的影响。研究结果表明:曲线轨道式隔震装置经优化后不仅零部件功能清晰,结构简单易加工,而且具备整体性强、运行质量高以及后期可扩展等优势。试验模型的零部件能充分发挥各自功能,尤其是抗侧移组件极大提高了模型的稳定性和可靠性,理论分析与试验结果吻合良好。结合案例所设计的样机虽具有较好的隔震性能,但限于非线性双自由度的结构特点,重复试验的响应结果存在差异,工程应用中应予以重视。当楼面波不易获取且隔震装置周期远离建筑自振周期时,依据楼面加速度放大系数,将调幅后的原始波作为隔震装置设计依据是可行的且结果偏保守。

计及柔性限流装置与直流断路器协同动作的电弧抑制暂态特性研究

直流系统的故障隔离是保证直流系统稳定运行的重要技术。针对传统故障隔离策略对直流断路器(direct current circuit breaker, DCCB)的性能要求较高的问题,提出了一种利用柔性限流装置(flexible current limiting device,FCLD)与DCCB协同动作的故障隔离策略。首先,研究了直流系统永久性故障和瞬时性故障情况下FCLD与DCCB的协同作用机理。其次,分析考虑FCLD电流抑制作用下DCCB开断过程的电弧暂态特性。最后,在Matlab/Simulink平台中进行仿真,验证所提协同策略的可行性。结果表明:FCLD可有效抑制DCCB的开断电弧;基于所提故障隔离策略,直流系统可在瞬时故障情况下实现平稳穿越,永久故障情况下实现DCCB的无弧开断。该策略降低了直流系统故障隔离过程中对DCCB的开断要求,提升了直流系统的故障穿越能力。

振动台控制室抗倾斜空气弹簧三维隔振平台研究

大型地震模拟振动台的运行给周围环境带来不可忽略的振动问题,影响精密仪器设备的正常使用及工作人员的舒适度。针对国家大型地震工程模拟研究设施振动台控制室面临的振动问题,提出一种基于带附加气室的空气弹簧和抗倾斜装置的大质量三维隔振平台。开展了隔振部件以及隔振平台的试验研究以及数值模拟分析,提出了抗倾斜装置的抗倾斜刚度理论计算公式。研究结果表明,带附加气室的锥型与直筒型膜式空气弹簧可实现约1 s竖向隔振周期,阻尼比达23%。试验中抗倾斜装置可有效控制人员偏心荷载造成的平台倾斜问题,平台倾斜角度减小达66%。所设计国家大型地震工程模拟研究设施隔振平台可大幅降低振动台运行产生振动影响,隔振效率达86%以上。

大跨连续梁桥竖向抗震性能研究

随着监测手段的不断进步,地震动的记录越来越完善,很多地震动的竖向分量被检测到并引起了专家学者的重视,尤其是高烈度区和震中区,地震动竖向分量甚至比水平分量还要显著。文章在综合分析国内外对多向地震以及多维隔震技术研究现状的基础上,研究了一种新型三维隔震装置(高阻尼橡胶碟簧三维隔震装置)在大跨度桥梁竖向抗震设计中的应用。结果表明:仅在桥墩安装三维隔震装置是最有效、经济的安装位置;竖向地震动分量对主梁纵向加速度有着放大作用,考虑竖向地震作用时,跨中竖向加速度不容忽视;三维减隔震装置较水平隔震支座有着更好的减隔震效果。

基于竞赛输电塔结构模型的减隔振装置

以浙江省第十八届大学生结构设计竞赛“输电塔结构设计与模型制作”赛题为背景,研究输电塔结构在断线动力载荷下的受力和结构选型。方案阶段对比分析了不同结构选型的优劣;融入减隔振理念进行设计:头部与主体脱开并巧妙设置圆形压槽轨道作为减隔振装置,通过头部沿轨道转动摩擦耗能减振,独具创新性。经试验验证,并结合解析计算与SAP2000软件电算分析,得到圆形轨道减隔振装置可有效减少结构的断线动力效应、提高主体结构的安全储备的结论;旨在为类似竞赛模型和相关实际工程提供实践和理论意义上的经验指导。

新型动力设备隔振减震器力学性能研究

隔振器可有效降低动力设备工作产生的高频振动,但低频地震下设备隔振器位移响应较大。将碟形弹簧和环形摩擦套筒分别作为竖向隔振和耗能单元,竖向耗能单元内设置振动间隙实现正常使用隔振和地震时减震的两阶段机制,形成一种新型动力设备隔振减震器。基于理论分析给出了隔振减震器的设计流程,并进行了算例设计,采用ABAQUS软件进行了隔振减震器的静力性能分析和动力设备整体系统的动力性能分析。结果表明:提出的隔振减震器及其系统的数值模拟与理论计算结果吻合较好;设计算例实现了设备正常工作时仅隔振、地震作用下耗能单元启动的两阶段隔振减震机制;竖向耗能单元使得设备竖向地震位移响应减小超过50%,水平向耗能单元使隔振减震器水平地震剪力减小超过80%,降低了隔振减震器地震倾覆和破坏的风险。

可崩解支架联合薄膜套粪便隔绝术预防低位直肠癌术后吻合口漏的效果分析

目的探讨可崩解支架联合薄膜套粪便隔绝术在预防低位直肠癌术后吻合口漏的应用。方法回顾性分析2016年1月至2023年4月在重庆医科大学附属永川医院行腹腔镜下低位直肠癌根治术(Dixon术式)的72名患者,其中行预防性造口的35名患者为观察组,行可崩解支架联合薄膜套粪便隔绝术的37名患者为研究组。比较2组患者的一般资料、手术时间、住院时间、总体并发症、住院费用、吻合口漏等指标。结果2组患者的一般资料(年龄、性别、BMI、NRS-2002评分、ASA分级、肿瘤分期、肿瘤距肛缘的距离)和合并基础疾病(糖尿病、高血压、其他心血管疾病、慢性阻塞性肺疾病)的比较差异均无统计学意义(P>0.05)。研究组的手术时间(238.0 vs 314.1 min,P<0.001)、术后住院时间(11 vs 12 d,P=0.040)、总体并发症(18.9%vs 51.4%,P=0.004)及住院费用(48327 vs 53092元,P=0.012)显著低于观察组。研究组吻合口漏率略低于观察组,但差异无统计学意义(2.7%vs 8.6%,P=0.350)。结论可崩解支架联合薄膜套粪便隔绝术缩短手术时间和住院时间,降低住院费用和减少总体并发症,且吻合口漏的风险不高于传统手术,可作为预防性造口的替代手术方式。

基于负刚度碟簧装置的竖向隔震支座力学性能研究

在竖向隔震中,为同时满足高静态刚度和低动态刚度的需求,提出一种基于预压碟簧的负刚度装置(disc spring negative stiffness device,DSNSD),利用其与已有的预压弹簧装置(prepressed spring device,PSD)集成为拥有高静低动刚度的竖向隔震支座(PSD-DSNSD隔震支座)。首先对DSNSD的构造与工作原理进行详述,建立相应的力学模型,再通过Python进行数值模拟,考察上述碟簧装置的力学性能,最后利用Abaqus建立PSD-DSNSD竖向隔震支座的有限元模型进行模拟。结果表明:加入DSNSD后竖向隔震支座的隔震刚度显著降低,验证了将DSNSD用于竖向隔震增效的可行性。说明DSNSD在启动后可提供负刚度,从而有效减小整体装置的竖向刚度。

尖扎黄河特大桥减隔震措施合理布设研究

尖扎黄河特大桥采用(141+366+141)m连续钢桁拱跨越黄河,其建设环境复杂,抗震设计根据两水准设防和两阶段设计的抗震原则,将设计地震作为功能性验算水准,将罕遇地震作为安全性验算标准,以实现“中震不坏、大震可修”的目标。本文探讨了不同抗震约束体系方案,经计算比选,采用横向双固定支座方案,能够降低水平地震作用。通过比较黏滞阻尼器和双曲面球型减隔震支座两种抗震措施方案,对墩台内力、滞回曲线进行分析计算,结果表明黏滞阻尼器耗能效果更好。通过在活动主墩设置可自动泄压速度锁定器,形成多墩协同抗震体系,牢牢结合抗震设防的性能要求,使得桥梁的抗震性能大幅提升,并有效减少了震后的修复工作,确保结构安全。

井下清洁施工系统的研发与应用

针对临盘油田液压封隔器坐封过程中容易出现液压通道堵塞的问题,研发了清洁施工系统。该系统主要包括液压封隔器沉淀过滤装置和防堵型油套平衡阀两部分,具有结构简单、成本低廉、可靠耐用、适用性强、可重复使用、极易推广等特点。自2012年在临盘油田投入实际使用至今,平均每年应用80口井左右,均无液压通道堵塞问题。该系统已成为临盘油田Y445型液压封隔器封层施工必备辅助工具,并形成规范化的施工流程,带来了丰富的成果应用效益,可以在全国各油田液压封隔器施工中推广使用,具有广阔的应用前景。

基于序贯蒙特卡洛模拟法的孤岛微电网可靠性评估

为评估孤岛型微电网的可靠性以及分析储能装置对系统可靠性的影响,提出基于序贯蒙特卡洛模拟法的孤岛微电网可靠性评估方案。首先,以孤岛型风柴储混合微电网系统作为研究对象,搭建分布式电源等关键设备的出力模型;其次,制定可靠性评估指标体系、不同的储能运行策略及负荷削减策略,在此基础上提出基于序贯蒙特卡洛模拟法的孤岛风柴储微电网可靠性评估算法;最后,通过对改进的RBTS Bus 6 F4孤岛系统进行仿真,量化分析了储能装置的运行策略、储能容量、容量配置对系统可靠性水平的影响。结果表明:合理的储能策略、适当增大储能容量以及适宜的储能系统配置方案等均可提高系统可靠性。

电力系统二次网络安全隔离装置设计要点探究

随着信息技术在电力系统中的应用越来越广泛,电力系统的运行管理也越来越依赖于信息技术,从而提高了电力系统的运行效率。目前,相关部门已对电网安全作出了相应的规定,但在实际的操作过程中,由于设备管理人员缺乏必要的安全意识、安全措施不到位等原因,导致电力系统运行过程中存在严重的信息泄漏、病毒入侵等现象。因此,为保证电力系统的正常运行,需要做好网络隔离装置设计工作。文章对隔离装置进行了介绍,并分析了其设计要点,以期为相关人员提供参考。