消能减振房屋抗震设计方法研究述评

阐述了安装有粘滞流体阻尼器的消能减振房屋抗震设计的原理和方法,包括阻尼器的工作原理和计算模型,性能试验和检验的标准,附加阻尼比公式的推导和抗震设计方法等。     

Loss of energy dissipation capacity from the deadzone in linear and nonlinear viscous damping devices

In a viscous damping device under cyclic loading, after the piston reaches a peak stroke, the reserve movement that follows may sometimes experience a short period of delayed or significantly reduced device force output. A similar delay or reduced device force output may also occur at the damper’s initial stroke as it moves away from its neutral position. This phenomenon is referred to as the effect of “deadzone”. The deadzone can cause a loss of energy dissipation capacity and less efficient vibration control. It is prominent in small amplitude vibrations. Although there are many potential causes of deadzone such as environmental factors, construction, material aging, and manufacture quality, in this paper, its general effect in linear and nonlinear viscous damping devices is analyzed. Based on classical dynamics and damping theory, a simple model is developed to capture the effect of deadzone in terms of the loss of energy dissipation capacity. The model provides several methods to estimate the loss of energy dissipation within the deadzone in linear and sublinear viscous fluid dampers. An empirical equation of loss of energy dissipation capacity versus deadzone size is formulated, and the equivalent reduction of effective damping in SDOF systems has been obtained. A laboratory experimental evaluation is carried out to verify the effect of deadzone and its numerical approximation. Based on the analysis, a modification is suggested to the corresponding formulas in FEMA 356 for calculation of equivalent damping if a deadzone is to be considered.     

台湾某钢框架大楼采用阻尼器补强结构减震效果评析

阻尼器是一种效果良好的减震装置,将阻尼器安装于结构中能够适时为结构体系提供阻尼力,从而减小地震作用对结构的破坏。黏滞阻尼器对振动的反应比较敏感,在结构受到较小振动时就可以发挥其减震效果,其阻尼力会随着振动周期和使用状态温度的不同而变化。当地震发生时,安装在结构中的阻尼器会消减地震作用,降低传导到主结构体系的地震能量,减小结构相对位移。本文介绍了黏滞阻尼器的工作原理和安装有黏滞阻尼器的结构体系的阻尼比的计算方法,对减震结构的减震效果的评析方法做出探讨,并以一安装有黏滞阻尼器的台湾某既有钢框架结构为例,分析了(1)该结构在遭受地震作用时的地震反应;(2)该结构体系在不同地震作用水平时的阻尼比,包括主体结构阻尼比和黏滞阻尼器阻尼比;(3)结构安装黏滞阻尼器后的减震效果。实例对本文的减震评析方法和减震效果进行了说明和分析,计算及分析结果表明利用黏滞阻尼器加固既有结构能够取得较好的减震效果,本文所提减震效果评析方法是一种实用有效的评析方法,对类似工程的减震评析具有一定的参考价值。     

巨子型有控结构体系中黏滞阻尼器参数研究

巨子型有控结构体系(Mega-sub Controlled Structure System,即MSCSS)是一种新型的超高层建筑结构体系.本文针对MSCSS的构造特点,提出一种安装黏滞阻尼器的新的布置方案,通过研究该布置方案中取不同黏滞阻尼器参数时巨子型有控结构体系在罕遇地震作用下的动力响应,提出了与该结构体系动力特...     

Predominant period and equivalent viscous damping ratio identification for a full‐scale building shake table test

The predominant period and corresponding equivalent viscous damping ratio, also known in various loading codes as effective period and effective damping coefficient, are two important parameters employed in the seismic design of base‐isolated and conventional building structures. Accurate determination of these two parameters can reduce the uncertainty in the computation of lateral displacement demands and interstory drifts for a given seismic design spectrum. This paper estimates these two parameters from data sets recorded from a full‐scale five‐story reinforced concrete building subjected to seismic base excitations of various intensities in base‐isolated and fixed‐base configurations on the outdoor shake table at the University of California, San Diego. The scope of this paper includes all test motions in which the yielding of the reinforcement has not occurred and the response can still be considered ‘elastic’. The data sets are used with three system identification methods to determine the predominant period of response for each of the test configurations. One of the methods also determines the equivalent viscous damping ratio corresponding to the predominant period. It was found that the predominant period of the fixed‐base building lengthened from 0.52 to 1.30 s. This corresponded to a significant reduction in effective system stiffness to about 16% of the original stiffness. The paper then establishes a correlation between predominant period and peak ground velocity. Finally, the predominant periods and equivalent viscous damping ratios recommended by the ASCE 7‐10 loading standard are compared with those determined from the test building. Copyright © 2017 John Wiley & Sons, Ltd.     

Evaluation of a passive gap damper to control displacements in a shaking test of a seismically isolated three‐story frame

Recent studies have indicated uncertainty about the performance limit states of seismically isolated buildings in very large earthquakes, especially if the isolator displacement demands exceed the seismic gap and induce pounding. Previous research has shown the benefit of providing phased supplemental damping that does not affect the isolation system response in a design event. A phased passive control device, or gap damper, was designed, fabricated, and experimentally evaluated during shake table testing of a quarter scale base‐isolated three‐story steel frame building. Identical input motions were applied to system configurations without a gap damper and with a gap damper, to directly assess the influence of the gap damper on displacement and acceleration demands. The gap damper was observed to reduce displacement demands by up to 15% relative to the isolated system without the gap damper. Superstructure floor accelerations increased substantially because of damper activation, but were limited to a peak of about 1.18 g. The gap damper reduces displacement most effectively if the ground motion contains one or more of the following characteristics: the spectral displacement increases with increasing period near the effective period of the isolation system, the motion is dominated by a single large pulse rather than multiple cycles at a consistent intensity, and the motion has a dominant component aligned with a major axis of the structure. Copyright © 2016 John Wiley & Sons, Ltd.     

Development and experimental evaluation of a passive gap damper device to prevent pounding in base‐isolated structures

Studies have shown the effectiveness of providing supplemental energy dissipation in base‐isolated structures to reduce displacements at the isolation level. A previous analytical study demonstrated the benefits of providing this energy dissipation at a specified gap larger than the design displacement. The gap before engagement allows the base isolation system to meet performance criteria in varying levels of ground excitation. Use of this ‘gap damper’ device eliminates undesirable effects often exhibited with large amounts of supplemental damping at lower intensity motions. Using results from an analytical study, the primary purpose of this research was to develop devices for practical implementation. Development of the devices demanded simplicity, feasibility, economy, and reliability to be an effective option in building design and construction. Multiple designs were proposed, and a final design was chosen based on selection criteria and finite element analyses. The device was designed and tested in Auburn University's Structural Research Lab. Experimental results were compared with theoretical models to verify behavior and make necessary adjustments for a shake table experiment. The design parameters were selected to accommodate re‐use of the device for the shake table test. Copyright © 2015 John Wiley & Sons, Ltd.     

摩擦与粘性流体耗能器串联体系动力分析

采用粘性屈服模型来模拟摩擦耗能器的力－速度关系，建立了摩擦与粘性流体耗能器串联耗能体系的动力分析方法．为考虑框架杆件和支撑材料的几何非线性，采用增量型Ｒｏｓｅｎｂｒｏｃｋ二级三阶半隐式Ｒｕｎｇｅ－Ｋｕｔｔａ法求解动力方程．比较了仅有摩擦耗能器体系与串联组合耗能体系的减振效果，分析了粘性流体耗能器参数对组合耗能体系减振效果的影响。     

基于地脉动和地铁振动的钢筋混凝土建筑结构响应分析

在北京城区的一栋钢筋混凝土建筑(Reinforced Concrete building,简称RC)中,进行历时两天的地脉动和地铁振动观测.介绍了利用地脉动和地铁振动信号研究RC建筑结构响应的观测方法、仪器设备、数据采集和数据处理方法.对观测数据进行两种分析:(1)对连续的地脉动背景噪声,采用H/V谱比法;(2)对经过的地铁列车作为震源产生的振动信号,采用地震干涉法,从而得到大楼的结构响应.这两种分析方法都表明:该RC大楼在东西向的共振频率是2.2 Hz,在南北向的共振频率是2.9 Hz.H/V谱比法表明,该大楼的噪声主要来源于东西方向的城市交通,主要包括地面交通和地铁.对地铁通过时产生的结构响应进行地震干涉分析,估算出这栋RC建筑的阻尼比是0.17,这能有效衰减共振.最后得出:利用地脉动背景噪声和沿线地铁振动作为信号输入,可能提供一种经济实用、灵活性好的结构响应分析方法,这是对仅利用强震动加速度分析进行建筑物易损性评估的传统分析方法的一种补充.     

Application of an earthquake early warning system and a real-time strong motion monitoring system in emergency response in a high-rise building

We apply a combination of earthquake early warning system (EEWS) and real-time strong motion monitoring system (RSMS) to emergency response for a high-rise building; The Kogakuin University has a 29-story high-rise building in Shinjuku Ward, Tokyo. The proposed strategy is based on the Plan, Do, Check, Action (PDCA) Cycle to brush up the systems and the users: in the “Plan” stage, we apply EEWS and RSMS to the building, where EEWS predicts not only short-period strong ground motions but also long-period ground motions [1]. The system is built into a building announcement system, an emergency elevator control system, and an email message system, which quickly send emails to the emergency response team. Meanwhile, RSMS provides information on seismic intensities at each floor of the building via the web browser in real time using the existing network in the building. In addition, the building response and structural damage can be estimated based on this information. The network system is impervious to the earthquake damage, because the network cable has extra length, there is, however, possible that a network system does not work due to power outage. Thus, we develop the network system that has uninterruptible power-supply system (UPS) and apply it to EEWS and RSMS. The high-rise building has the emergency call units to the security control center in the building on every floor. The emergency call line, however, will be busy promptly, because it is able to use only one line. Therefore, we installed IP telephone which uses the network system on main floors. UPS will work about 30 min after a major earthquake, it is supposed to be enough time for gathering the damage information about the building during initial response. In the “Do” stage, we prepare emergency response instruction manuals and educate the faculty members and students to carry out promptly emergency response. In the “Check” stage, the validity of the proposed systems are verified by carrying out an earthquake drill in an actual high-rise building. The earthquake drill confirmed that our proposed approach is valid. In the final “Action” stage, we improve these systems and emergency response manual and educate people in the building how to use effectively these systems.     

Damping‐adjusted combination rule for the response spectrum analysis of base‐isolated buildings

The classical response spectrum method continues to be the most popular approach for designing base‐isolated buildings, therefore avoiding computationally expensive nonlinear time‐history analyses. In this framework, a new method for the seismic analysis and design of building structures with base isolation system (BIS) is formulated and numerically validated, which enables one to overcome the main shortcomings of existing techniques based on the response spectrum method. The main advantages are the following: first, reduced computational effort with respect to an exact complex‐valued modal analysis, which is obtained through a transformation of coordinates in two stages, both involving real‐valued eigenproblems; second, effective representation of the damping, which is pursued by consistently defining different viscous damping ratios for the modes of vibration of the coupled BIS‐superstructure dynamic system; and third, ease of use, because a convenient reinterpretation of the combination coefficients leads to a novel damping‐adjusted combination rule, in which just a single response spectrum is required for the reference value of the viscous damping ratio. The proposed approach is specifically intended for design situations where (i) the dynamic behaviour of seismic isolators can be linearised and (ii) effects of nonproportional damping, as measured by modal coupling indexes, are negligible in the BIS‐superstructure assembly. Copyright © 2012 John Wiley & Sons, Ltd.     

Structural and nonstructural performance of a seismically isolated building using stable unbonded fiber‐reinforced elastomeric isolators

Stable unbonded fiber‐reinforced elastomeric isolators (SU‐FREIs) exhibit a characteristic horizontal softening and stiffening response, similar to other adaptive devices such as the triple friction pendulum and sliding systems with variable curvature. The transition between the softening and stiffening occurs at a displacement corresponding to a unique deformation known as full rollover. In this paper, the full rollover displacement of SU‐FREIs is altered by using modified support geometry (MSG), a geometric modification of the upper and lower supports applied to tailor the hysteresis loops of the isolator. Experimental results are used to calibrate a numerical model of a base‐isolated structure. The model demonstrates that the stiffening regime provides minimal restraint against displacements during events that meet or exceed the maximum considered earthquake. A parametric study revealed that the level of stiffening required to restrain displacements during large events is significant. This increase in stiffness is reflected in an increase in the response of the structure and light nonstructural components. Full rollover and MSG is considered advantageous to maintain horizontal stability and provide control over the stiffening of SU‐FREIs. Copyright © 2015 John Wiley & Sons, Ltd.     

北京边界层大气污染物的垂直廓线监测与分析

基于扫描差分光学吸收光谱（DOAS）系统,于2007年8月27日~9月4日期间对北京市朝阳区大气污染物SO2,HCHO,O3和NO2的垂直分布进行了连续监测,并对污染物垂直廓线进行了分析,详细探讨了SO2垂直分布特征以及夜间NO对O3的滴定作用.结果表明,SO2浓度通常没有明显垂直分层分布特征,但在清晨风速较低时呈现负梯度变化.研究发现夜间O3、NO和NO2之间存在稳态作用,表明城市区域O3的滴定主要来自于地面NO的直接排放,显示出NO的滴定作用对夜间O3、NO和NO2的垂直变化起到重要作用.     

Use of a shared tuned mass damper (STMD) to reduce vibration and pounding in adjacent structures

The dynamic response of tall civil structures due to earthquakes is very important to civil engineers. Structures exposed to earthquakes experience vibrations that are detrimental to their structural components. Structural pounding is an additional problem that occurs when buildings experience earthquake excitation. This phenomena occurs when adjacent structures collide from their out‐of‐phase vibrations. Many energy dissipation devices are presently being used to reduce the system response. Tuned mass dampers (TMD) are commonly used to improve the response of structures. The stiffness and damping properties of the TMD are designed to be a function of the natural frequency of the building to which it is connected. This research involves attaching adjacent structures with a shared tuned mass damper (STMD) to reduce both the structures vibration and probability of pounding. Because the STMD is connected to both buildings, the problem of tuning the STMD stiffness and damping parameters becomes an issue. A design procedure utilizing a performance function is used to obtain the STMD parameters to result in the best overall system response. Copyright © 2001 John Wiley & Sons, Ltd.     

Soil‐structure system frequency and damping: Estimation from eigenvalues and results for a 2D model in layered half‐space

This paper presents a formulation for estimation of the frequency and damping of a soil‐structure interaction system based on the classical modal analysis and solving the system eigenvalue problem. Without loss of generality, the structure is represented by a single degree of freedom oscillator, while the soil effects are included through impedance functions for in‐plane motion of a 2D rigid foundation. For the results presented in this paper, the impedance functions were computed by the indirect boundary element method for a rectangular foundation embedded in a soil layer over elastic bedrock. The study shows that the classical modal‐analysis approach works well, with the exception of squat, stiff structures, even though the impedance functions are frequency‐dependent and the soil‐structure interaction system does not possess normal modes. The study also shows that system frequency and damping are independent of the wave passage effects, contrary to findings of some previous studies, and that the site conditions, represented by the soil‐layer thickness and stiffness contrast between bedrock and soil layer, have significant influences on both system frequency and system damping. Finally, the paper examines the accuracy of some of the simple methods for estimation of these two system parameters and comments on some conflicting conclusions of previous studies about the effects of foundation embedment.     

Predictors of urban variable source area: a cross‐sectional analysis of urbanized catchments in the United States

Many studies have empirically confirmed the relationship between urbanization and changes to the hydrologic cycle and degraded aquatic habitats. While much of the literature focuses on extent and configuration of impervious area as a causal determinant of degradation, in this article, I do not attribute causes of decreased watershed storage on impervious area a priori. Rather, adapting the concept of variable source area (VSA) and its relationship to incremental storage to the particular conditions of urbanized catchments, I develop a statistically robust linear regression‐based methodology to detect evidence of VSA‐dominant response. Using the physical and meteorological characteristics of the catchments as explanatory variables, I then use logistic regression to statistically analyze significant predictors of the VSA classification. I find that the strongest predictor of VSA‐type response is the percent of undeveloped area in the catchment. Characteristics of developed areas, including total impervious area, percent‐developed open space and the type of drainage infrastructure, do not add to the explanatory power of undeveloped land in predicting VSA‐type response. Within only developed areas, I find that total impervious area and percent‐developed open space both decrease the odds of a catchment exhibiting evidence of VSA‐type response and the effect of developed open space is more similar to that of total impervious area than undeveloped land in predicting VSA response. Different types of stormwater management infrastructure, including combined sewer systems and infiltration, retention and detention infrastructure are not found to have strong statistically significant effects on probability of VSA‐type response. VSA‐type response is also found to be stronger during the growing season than the dormant season. These findings are consistent across a national cross‐section of urbanized watersheds, a higher resolution dataset of Baltimore Metropolitan Area watersheds and a subsample of watersheds confirmed not to be served by (combined sewer systems). Copyright © 2016 John Wiley & Sons, Ltd.     

引黄水源水库平-丰水期有色可溶性有机物(CDOM)的来源、组成及差异分析

为探究引黄水源水库——门楼水库平水期和丰水期有色可溶性有机物(CDOM)的组成特征、来源及差异,运用紫外—可见光谱技术(UV-vis)和三维荧光光谱(EEMs)技术,结合平行因子分析法(PARAFAC)分析2022年5月(平水期)和2022年7月(丰水期)有色可溶性有机物含量及组分变化。研究结果表明:PARAFAC识别出2类荧光组分,分别是C1(Ex=355 nm,Em=476 nm,类腐殖质组分)和组分C2(Ex=225 nm,Em=320 nm,类蛋白组分);丰水期CDOM组分荧光强度显著高于平水期。CDOM光谱参数表明,门楼水库水体处于中营养状态,水体CDOM受新生内源和外源输入共同影响,以自生源为主;水库CDOM具有相对分子量小、腐殖化程度较弱的特点。丰水期水库富营养化水平和CDOM相对浓度低于平水期;丰水期CDOM疏水性组分比例和芳香化程度高于平水期。水质理化指标、CDOM组分和光谱参数相关性分析结果表明SUVA₂₆₀和SUVA₂₈₀与DOC呈显著负相关,说明紫外—可见光谱参数在一定程度上可以用来估算DOC的浓度;Chl.a浓度作为...     

Assessment of soil erosion in a monsoon-dominated mountain river basin in India using RUSLE-SDR and AHP

The long-term average annual soil loss (A) and sediment yield (SY) in a tropical monsoon-dominated river basin in the southern Western Ghats, India (Muthirapuzha River Basin, MRB; area: 271.75 km²), were predicted by coupling the Revised Universal Soil Loss Equation (RUSLE) and sediment delivery ratio (SDR) models. Moreover, the study also delineated soil erosion risk zones based on the soil erosion potential index (SEPI) using the analytic hierarchy process (AHP) technique. Mean A of the basin is 14.36 t ha^?1 year^?1, while mean SY is only 3.65 t ha^?1 year^?1. Although the land use/land cover types with human interference show relatively lower A compared to natural vegetation, their higher SDR values reflect the significance of anthropogenic activities in accelerated soil erosion. The soil erosion risk in the MRB is strongly controlled by slope, land use/land cover and relative relief, compared to geomorphology, drainage density, stream frequency and lineament frequency.     

抚仙湖有色可溶性有机物的来源组成与时空变化

基于2017年1-12月在抚仙湖开展的逐月观测,利用紫外-可见吸收光谱和三维荧光光谱技术探讨该湖有色可溶性有机物（CDOM）的来源组成及时空变化特征.12个月CDOM吸收值a（254）的均值为3.47±0.57 m^-1,范围为1.82~5.22 m^-1,说明CDOM丰度较低.平行因子分析结果给出了2种类酪氨酸荧光组分（C1和C3）、1种类色氨酸荧光组分（C2）、1种类腐殖质荧光组分（C4）,12个月内源组分（C1+C3）对总荧光强度的平均贡献为65.81%±15.38%,外源组分（C2+C4）的平均贡献为34.19%±15.38%;荧光指数FI的均值为1.73±0.14,腐殖化指数HIX的均值为1.02±0.37,生源化指数BIX的均值为1.23±0.27,说明CDOM主要为微生物内源产生.时空变化方面,春（3-5月）、夏（6-8月）、秋（9-11月）和冬（1、2、12月）季的a（254）分别为3.20±0.47、3.76±0.64、3.67±0.50和3.23±0.38 m^-1,夏季和秋季均显著高于冬季和春季;CDOM丰度及内外源组分的空间分布具有季节异质性,可能与流域土地利用、河流输入、降雨、温度、光辐射等因素有关.     

Natural 222Rn as a tracer of mixing and volatilization in a shallow aquifer during a CO2 injection experiment

This study aims to evaluate the application of ²²²Rn in groundwater as a tracer for monitoring CO₂ plume migration in a shallow groundwater system, which is important to detect potential CO₂ leakage in the carbon capture and storage (CCS) project. For this research, an artificial CO₂-infused water injection experiment was performed in a shallow aquifer by monitoring hydrogeochemical parameters, including ²²²Rn. Radon in groundwater can be a useful tracer because of its sensitivity to sudden changes in subsurface environment. To monitor the CO₂ plume migration, the data were analysed based on (a) the influence of mixing processes on the distribution of ²²²Rn induced by the artificial injection experiment and (b) the influence of a carrier gas role by CO₂ on the variation of ²²²Rn. The spatio-temporal distributions of radon concentrations were successfully explained in association with horizontal and vertical mixing processes by the CO₂-infused water injection. Additionally, the mixing ratios of each monitoring well were calculated, quantitatively confirming the influence of these mixing processes on the distribution of radon concentrations. Moreover, one monitoring well showed a high positive relationship between ²²²Rn and Total dissolved inorganic carbon (TIC) by the carrier gas effect of CO₂ through volatilization from the CO₂ plume. It indicated the applicability of ²²²Rn as a sensitive tracer to directly monitor CO₂ leakage. When with a little effect of carrier gas, natural ²²²Rn in groundwater can be used to compute mixing ratio of CO₂-infused water indicative of CO₂ migration pathways. CO₂ carrier gas effect can possibly increase ²²²Rn concentration in groundwater and, if fully verified with more field tests, will pose a great potential to be used as a natural tracer for CO₂.