Experimental study on the sandbag isolator of buildings for subway-induced vertical vibration and secondary air-borne noise

This paper presents a new geosynthetics isolator composed of stacked sandbags for buildings’ base-isolation method to improve human comfort under subway-induced environmental vibrations. The static and dynamic mechanical properties of the isolator are tested in a laboratory first. Then field experiments are performed with a full-scale building to investigate the effectiveness of the isolator. The results indicated that the bearing capacity is mainly influenced by the soft contact interfaces between different sandbags, and is sufficient for most low-rise and mid-rise buildings. Similar to some springs in a series, the soft contact interfaces make the vertical stiffness of the isolator low enough to isolate vibrations. The friction forces between sand particles are a benefit to dissipating energy, which increases the damping ratio to 14%. After the installation of geosynthetics isolators, the vertical vibration and secondary air-borne noise inside the building are effectively suppressed, and therefore the comfort for residents is enhanced. Further, there is no negative impact caused by automobile vibrations on the isolated building because the damping ratio of the isolator is high enough to resist resonant amplitudes. These results demonstrate that the isolator is feasible for buildings near subway transportation.     

基于一种新型铅芯橡胶隔震支座的力学参数试验研究

通过对不同结构构造的铅芯橡胶支座进行水平动态力学试验,系统研究了铅芯橡胶支座动态力学性能与其结构构造及外加动载之间的关系。在支座直径、橡胶和薄钢板厚度不变的情况下,分析了不同倾角或曲率的铅芯橡胶隔震支座在竖向荷载和剪切荷载作用下的力学性能;研究了竖向刚度、水平等效刚度、屈服后刚度、屈服力、等效阻尼比等的变化规律。研究结果表明,竖向刚度随倾角或曲率的增加呈减小趋势,水平等效刚度、屈服后刚度、屈服力、等效阻尼比随倾角或曲率的增加呈增大趋势;同时通过数值分析精确的验证了新型铅芯橡胶支座具有良好的减隔震效果。     

串联隔震橡胶支座力学性能试验研究

通过本文的研究,了解串联天然隔震橡胶支座和串联铅芯隔震橡胶支座基本性能及其各种水平相关性能。文中分别对4-LNR—D100和4-LRB—D100支座进行了水平基本性能和剪切性能的应变相关性、压应力相关性及加载频率相关性试验,研究了其对串联支座水平性能的影响。对比分析了单个支座和串联支座基本性能的差异,同时研究了是否有竖向约束对部分相关性能的影响。研究结果表明,由于弯曲变形的存在,4-LNR—D100的水平刚度较1-LNR—D100值的1／4低,4-LIRB-D100的屈眼后刚度、等效刚度较1-LRB—D100值的1／4低,4-LRB—D100的屈服力较1-LRB-D100值也低,但两者等效阻尼比变化不大;但竖向约束对串联支座的应变相关性影响较大。     

基于准零刚度特性的结构竖向隔振系统研究

基于准零刚度的原理,提出将并联碟形弹簧和线性压缩弹簧的准零刚度系统用于建筑结构竖向隔振。基于系统的位移-回复力关系,建立了隔振系统竖向运动控制方程,采用谐波平衡法求解了系统的幅频响应和传递率。通过数值仿真对理论推导进行了验证,并根据传递率的变参数分析结果,探讨了系统不同激励幅值引起的频率偏移,以及不同阻尼比对传递率曲线的影响。由准零刚度系统和等效线性系统的传递率曲线对比,证明了与等效线性隔振系统相比,准零刚度系统具有更低的隔振起始频率和更小的传递率优势。通过OpenSees软件的二次开发,实现了准零刚度系统的数值本构模型。基于数值本构模型开发,对采用准零刚度系统的竖向基础隔振结构进行了地震和地铁振动输入下的响应时程计算,验证了准零刚度系统的竖向隔振效果。     

碟形弹簧竖向减震装置的性能试验研究

基础隔震技术是目前应用最广泛的结构控制方法,但是,目前这种技术只是最大限度地减少或隔离水平地震作用,而对竖向地震作用几乎没有影响。为改善隔震技术在隔离竖向地震中的限制,研制了一种由碟形弹簧和粘弹性阻尼器组合而成的碟形弹簧竖向减震装置,并对其进行了在静载和动载作用下的力学性能试验研究, 给出了该装置在竖向静力和动力作用下的等效刚度和阻尼比,建立了恢复力模型,试验研究表明,碟形弹簧竖向减震装置能有效的解决竖向大承载力和竖向阻尼的难题,力学性能优良且稳定,加工制作容易,是一种比较理想的竖向减震装置。     

铅芯废旧轮胎隔震垫（LRTP）力学性能试验研究

针对“小震致灾”甚至“小震大灾”的我国村镇房屋,为提高其抗震能力,研发一种造价低廉、构造简单、施工简便、后期维护成本低的铅芯废旧轮胎隔震垫（LRTP）。通过铅芯废旧轮胎隔震垫（LRTP）和废旧轮胎隔震垫（RTP）竖向和水平向力学性能对比试验,详细分析研究了两者的竖向极限承载力、竖向压缩刚度、抗剪承载力、水平等效刚度和等效阻尼比等力学参数及破坏模式,得到铅芯废旧轮胎隔震垫（LRTP）的力学性能显著优于废旧轮胎隔震垫（RTP）,其中LRTP的抗剪承载力和极限剪应变显著高于RTP,且具有更强的耗能能力,其等效阻尼比接近工程常用的铅芯橡胶支座 (LRB) ,此外,LRTP造价低廉环保,故十分适合用于提高我国村镇房屋抗震能力,从而减少人员伤亡和经济损失。     

Experimental study on vibration reduction by using soilbags

The effectiveness of soilbags in reducing mechanical vibration is investigated, and the influential factors are examined through a series of laboratory tests, including cyclic lateral shear tests, vertical excitation tests and small shaking table tests as well as a soilbag-filled trench field test. The test results illustrate that soilbags have a relatively high damping ratio and variable horizontal stiffness, which are greatly influenced by the materials inside the bags at low vertical stress but become nearly independent of the materials inside the bags at high vertical stress. We find that vertical and horizontal vibrations can be effectively reduced through the use of soilbags.     

串联式压缩型橡胶隔振器的力学性能及设计建议

串联式压缩型橡胶隔振器是一种新型橡胶隔振器,由橡胶与钢板分层叠合而成,具有较高的竖向承载力和竖向刚度,较低的水平刚度,适用于以水平振动为主的重型机器的隔振,得到广泛应用,但其动力力学参数的计算,目前尚没有明确的算式。结合现有的相关研究成果,提出其动力力学参数的计算确定方法,并对此类隔振器的设计提出了建议。     

斜向滑动摩擦三维隔震装置的滞回模型及其隔震效果

基于铅芯橡胶隔震支座的力学性能特点,研发了斜向滑动摩擦三维隔震装置。基于该三维隔震装置的组成构造和变形机理,提出了其竖向荷载-位移滞回模型,给出了各阶段支座刚度的计算公式。对三维隔震装置进行的竖向压缩拟静力试验结果表明：三维隔震支座在竖向具有变刚度特性,其滞回曲线饱满,不同加载速率和位移幅值下力学性能稳定;提出的滞回模型与试验结果基本吻合,可以有效模拟三维隔震装置的竖向滞回性能。通过三维隔震结构缩尺模型的振动台试验,认为三维隔震装置与传统水平隔震支座具有相当的水平隔震效果,同时可控制结构的竖向响应。     

模块化钢框架变摩擦摆隔震结构抗震性能研究

模块化建筑具有整体装配率高,施工绿色环保、高效等优点,然而其抗震性能相对较差,震后修复成本高。将隔震技术应用到模块化建筑中,可在不改动上部结构的前提下,改善其整体抗震能力。相比传统橡胶隔震技术,摩擦摆隔震技术具有承载力大、工业化程度高、湿作业少等优势。为此,研发了一种自适应变摩擦摆隔震支座,分析了该支座力学特性,确定其有限元模拟方法。对变摩擦摆隔震支座进行不同工况下剪切性能试验,试验和有限元模拟结果相对误差均在10%以内,验证了有限元模拟方法的正确性。基于GB/T 51408—2021《建筑隔震设计标准》提出模块化钢框架变摩擦摆隔震结构一体化直接设计方法,以实际工程为背景,设计模块化钢框架摩擦摆和变摩擦摆隔震结构,并对非隔震结构和隔震结构的抗震性能进行对比分析。研究表明：相比摩擦摆隔震支座,所提出变摩擦方式可实现支座等效刚度增加11%左右,等效阻尼比增加18%左右;相比摩擦摆支座隔震结构,变摩擦摆支座隔震结构的楼板加速度、层间位移角、层间剪力和上部结构损伤程度略有增加,但隔震层位移明显减小,且这种特性随地震动强度的增加而愈明显,体现了变摩擦摆支座的自适应性。     

耦联结构体系的半主动控制

基于变刚度和变阻尼的原理提出两种用于耦联结构体系的半主动控制装置,在建立这两种半主动控制时耦联结构振动控制体系的运动方程的同时,还提出一种新的广泛适用于一般开关控制型半主动控制系统的控制算法,推导出两种半主动控制的开关控制律,并对结构的动力参数对控制效果的影响规律进行研究。为检验所提出的两种半主动控制装置及新半主动控制算法的有效性,针对不同的算例进行了计算机仿真分析。结果表明,对两相邻结构进行控制是必要的和有效的,所提出的两种半主动控制装置与控制算法是非常有效的,可显著增强耦联结构体系的安全性与舒适性。与变刚度控制相比,变刚度变阻尼控制由于在装置中附加了阻尼,可以取得比变刚度控制更为有效的减震控制效果。     

橡胶隔震支座基本力学性能试验研究

为了满足三维隔震装置对承载元件的需要,设计了一种新型的厚层橡胶隔震支座,该支座的最大特点是能够同时发生水平和竖向变形。通过水平剪切和竖向压缩试验研究了橡胶隔震支座在不同振幅、不同频率组合下的力学性能。试验研究表明,厚层橡胶隔震支座在水平方向的基本力学性能是良好、稳定的,在竖向具有大变形能力。     

Brake systems for protecting large structures from seismic or aerodynamic instability

A new passive hydromechanical system for damping sustained oscillations in buildings and bridges under earthquakes or wind is introduced, which is most effective in resonance conditions. The system is characterized by simplicity of construction and high functional efficiency, yet consumes very little external energy to replace oil lost by leakage. The basis of the system is two spring-loaded check-valves (or single-stage relief valves) installed in a braking cylinder fixed to the ground and whose piston exerts control action on the structure via cables of appropriate axial stiffness. The configuration and functioning of the braking system are described and its performance evaluated for vertical multistorey structures and for horizontal girder structures.     

FPS隔震结构的水平和竖向振动响应分析

建立了FPS(FrictionPendulumSystem)隔震多层剪切型结构水平和竖向耦合振动微分方程 ,通过时程响应计算阐述了水平地震作用下FPS的隔震效果和结构的水平和竖向振动响应规律。     

装配式减震墙板RC框架结构抗震性能试验研究

通过对4榀两层两跨的装配式减震墙板框架、空框架和普通墙板框架的低周反复加载试验，对比研究了装配式减震墙板RC框架结构的破坏特征、滞回性能、承载能力、刚度退化和耗能能力等。试验结果表明：装配式减震墙板框架结构的滞回曲线饱满，耗能能力强，其等效黏滞阻尼系数在0.13以上，较装配式空框架和普通墙板框架有明显提高；横条型和竖条型墙板对装配式减震墙板框架结构的抗震性能影响不大，二者对框架结构水平承载力和抗侧刚度的附加效应均远小于普通墙板，可减少对装配式框架造成过强约束；装配式减震墙板框架结构的承载力衰减速率和刚度退化速率都较普通墙板框架结构缓慢，增强了结构强震作用下的承载能力；当结构层间位移角达到1/50时，装配式框架中普通墙板端部开裂并被压碎，而减震墙板并未出现破坏。     

Probabilistic seismic risk assessment of modified pseudo-negative stiffness control of a base-isolated building

Pseudo-negative stiffness (PNS) control of a base-isolated structure, which has a large damping ratio at the isolation level, is used to suppress isolator displacement without large force transmission to the superstructure during extreme earthquakes. However, potential increases in floor acceleration in the superstructure are induced by the large damping ratio, especially for low-to-moderate seismic input level. In consideration of structural functionality and safety, a modified PNS (MPNS) control scheme based on the ‘ideal isolation control principle’ is proposed, considering different seismic intensity levels. The effect of the MPNS control is investigated from three aspects, namely floor acceleration, inter-storey drift and isolator displacement within a probabilistic performance-based seismic engineering framework. Comparisons are made between MPNS control, conventional PNS control and passive damping control. A benchmark base-isolated building is used as a case study. In the seismic performance evaluation, the seismic intensity measures for different response parameters are optimised. An extensive parametric study is also conducted to identify the optimal control parameter to conform to the ideal isolation control principle. Results demonstrated that the MPNS control is an effective solution to the challenging problem of improving structural functionality at low seismic intensity, as well as structural safety from collapse at extreme seismic intensity.     

A review of the diagrid structural system for tall buildings

Unlike vertical columns of traditional structure, diagrid structural systems for tall buildings have special inclined columns. Due to the inclined columns, a diagrid structural system for tall buildings produces axial force along the column direction under horizontal load, which has the advantage of resisting horizontal wind load and seismic load and gives more freedom to architectural design, so a diagrid structural system for tall buildings becomes an effective new structure style for tall and super‐tall buildings. Theories and tests regarding the diagrid structural system for tall buildings have been intensely researched since the exterior tube of diagrid structural system for tall buildings was first proposed by Torroja in his seminal book. At present, studies for mechanical characteristics, joint form, theories, and tests have been systematized. This paper systematically summarizes existing research achievements of the diagrid structural system for tall buildings and confirms that the structure has larger lateral stiffness and good seismic performance. Based on the favourable performance of concrete‐filled steel tubes, this paper advises the use of concrete‐filled steel tube columns as the columns in diagrid structural systems for tall buildings.     

竖向土工加筋体对碎石桩承载变形影响的模型试验研究

在碎石桩桩顶一定深度内包裹竖向土工加筋体形成筋箍碎石桩,能有效提高碎石桩的承载能力,控制复合地基沉降量。采用分级加载方式,设计并完成了两组较大比例室内模型试验,对比分析了筋箍碎石桩和传统碎石桩的承载变形特性,进而探讨了筋箍碎石桩的加筋机理和鼓胀变形模式,重点分析了竖向土工加筋体的应力应变特征。分析结果表明：竖向土工加筋体能有效约束碎石桩的侧向鼓胀,在微小侧向变形内提供足够的径向约束应力;筋箍碎石桩的最大鼓胀变形多发生于加筋体以下区域,其破坏模式与筋体材料、桩体、桩周土体及其相互作用和协调变形密切相关;筋箍碎石桩的桩顶和桩底桩土应力比均明显大于传统碎石桩,上部土工加筋体在提高桩体刚度的同时,可有效地将上部荷载传递至桩底较好土层。     

大板结构接缝的强度和刚度

本文介绍了大板结构接缝强度和刚度方面的试验研究成果,包括混凝土的纯剪强度和接缝材料的粘结抗剪强度、剪跨比对截面抗剪强度的影响、轴压力与抗剪力的关系,“剪切-摩擦”抗剪力、竖向接缝的抗剪强度和变形性能、多因素水平接缝的总体抗剪强度和刚度、连系梁接缝的选型及抗剪强度、水平接缝的抗压强度和刚度等内容。本研究成果可供改进地震区大板结构的设计和大板规程的修编参考。     

基于老化-海蚀循环的高阻尼橡胶支座剪切性能相关性试验研究

对高阻尼橡胶支座(HDR)开展了长达150 d的老化-海蚀循环试验,定期测试其剪切性能,分析总结了老化-海蚀循环作用时间及剪应变对HDR剪切性能的影响规律。试验结果表明,在老化-海蚀循环作用时间相同时,水平等效刚度比、等效阻尼比的比值和屈服后刚度比均随剪应变的增大而减小,屈服力比则随剪应变增大而增大;在剪应变相同时,随老化-海蚀循环作用时间的增长,其水平等效刚度比和屈服后刚度比总体呈增大趋势,且剪应变越大,水平等效刚度比增长幅度越大。等效阻尼比随试验时间的增长整体呈减小趋势,而屈服力比则随试验时间先增大后减小。拟合试验数据得到HDR水平等效刚度比、等效阻尼比的比值、屈服后刚度比和屈服力比随老化-海蚀循环时间及剪应变双参数的变化规律公式,可为隔震设计人员和深入开展海洋环境下HDR性能的变化规律研究提供理论依据。