消能支撑加固底部框架砌体房屋的弹塑性地震反应分析

本文采用弹塑性时程分析方法,对底部框架多层砌体房屋在不同烈度罕遇地震作用下进行了抗震性能评估;研究了在底部框架内增设消能外包混凝土无粘结钢支撑对房屋抗震性能的影响;对增设消能支撑加固方案和增设抗震墙加固方案进行了对比分析。分析结果表明,在底层框架砌体房屋的底层增设消能支撑可显著降低底层框架的最大层间位移,控制结构的塑性损伤,提高结构的抗震性能。增设消能支撑加固方案与增设抗震墙加固方案相比,结构加固更合理、更易实施。     

震损钢筋混凝土结构减震加固研究进展

震损钢筋混凝土结构如何考虑损伤影响以进行减震加固设计是值得研究的问题。本文介绍了国内外相关建筑加固与减震设计的系列标准规范,基于震损结构的各种加固工况探讨了减震加固技术的适用范围,概括了国内外有关消能减震加固技术的发展及其应用于震损结构加固的研究现状,简述了灾后震损结构进行减震加固的几种设计方法,并列出了部分典型的减震加固工程实例。最后,在已有研究的基础上,指出了现阶段震损结构减震加固研究中仍存在的一些问题。     

磁流变阻尼智能加固体系的试验研究

提出利用磁流变阻尼器(MRD)对有损伤结构进行智能加固。根据MRD的特点,结合我国抗震设计规范,给出MRD智能加固的三个等级性能目标,对其进行量化,并确定MRD智能加固的设计要点。利用MRD对一有损伤钢筋混凝土框-剪偏心结构进行抗震加固,并进行振动台试验。结果表明,采用MRD智能加固后的结构抗震性能大大提高,优于用被动控制方法加固的结构。     

Post-earthquake loss assessment based on structural component damage inspection for residential RC buildings

There is substantial evidence showing that the seismic performance of many existing buildings may be inadequate to resist another strong earthquake. The losses from a devastating earthquake are always huge. In order to prevent damage extension and to restore the damaged community as quickly as possible, immediate post-earthquake damage assessment is always conducted through site inspection on structural components within a restricted short period of time to screen buildings that are damaged to certain levels or in danger of collapse. Without detail financial loss estimation, engineers have to face the challenge to decide whether a badly damaged building is worth retrofitting for sustainability, or needs to be demolished because existing loss estimation models are not based on the post-earthquake damage rating system. Based on some post-earthquake damage data of RC residential buildings, this paper aims to link inspected component damage level, building damage state and direct financial loss in terms of repair to replacement cost ratio. Damage of structural components are quantified by a set of damage factors and finally integrated as a building damage indicator. Building repair to replacement cost ratio and storey repair to replacement cost ratio corresponding to various damage levels of RC residential buildings have been estimated. With these statistical data, relationships of building damage indicator to repair to replacement cost ratio has been built from regression analysis.     

A new damage index for RC buildings based on variations of nonlinear fundamental period

Many vital reinforced concrete (RC) buildings experience moderate or severe earthquakes in their lifetime because they are located in hazardous areas. However, their importance cause to be evaluated by different types of damage functions. In these procedures, structures are usually modelled. These models neither correctly display the effects of the cracks that emerge and plastic hinges nor precisely consider the effects of asymmetric configuration and infill panels. Furthermore, the actual nonlinear dynamic behaviour of existing buildings could be evaluated by assessing nonlinear dynamic characteristics such as the fundamental period. These dynamic characteristics, which are obtained by some field tests such as forced and/or ambient vibration methods, comprise the aforementioned effects. This paper offers a damage index (pattern) for seismic damage assessment of RC buildings based on the variation of the nonlinear fundamental period, which is obtained by field tests. Finally, the seismic situation of existing RC buildings that have experienced an earthquake is precisely and expeditiously assessed by this new damage index. Copyright © 2010 John Wiley & Sons, Ltd.     

Analysis of lifetime losses of low-rise reinforced concrete buildings attacked by corrosion and earthquakes using a novel method

In the estimation of the losses caused by an earthquake for a reinforced concrete (RC) building, the effect of corrosion of the reinforcing steel incurred by environmental conditions, e.g. carbonation and chloride ions, is seldom mentioned because of the corrosion with uncertainty and time dependence. However, because the structural capacity of a corroded RC building declines over time, one must apply an appropriate method that estimates the structural capacity of an RC building in a corrosive environment. Therefore, this work integrated degradation factors into the structural properties of a corroded RC building. Additionally, by considering life-cycle earthquake events, lifetime losses resulting from earthquakes and corrosion can be derived. This work can help both owners and investors to identify lifetime losses of RC buildings due to seismic structural damage, including the corrosion effect, within a specified service life. Although the case study only addresses a selection of the most appropriate concrete cover depth for an RC building corroded by chloride ions, the proposed procedure can be utilised when making decisions about whether to prevent building deterioration based on economic considerations.     

Time-dependent seismic fragility curves on optimal retrofitting of neutralised reinforced concrete bridges

The neutralisation (carbonation) of concrete usually results in material deterioration of a reinforced concrete (RC) bridge, so that the seismic capacity of the structure tends to degrade over time. This paper determined the deteriorated plastic hinge properties of the neutralised RC bridge column and performed the pushover analysis to obtain the decayed seismic capacity curves. As a result, the time-dependent fragility curves with respect to some representative damage levels can be established and the possible seismic loss can be expressed as a function of service time.

The S-surfaces representing retrofitting cost versus service time for a neutralised RC bridge subjected to different earthquake levels were determined quantitatively in a case study. Throughout the whole life-cycle of a bridge, critical service times corresponding to dramatically increased slopes in the S-surface associated with cost elevations can be identified to assist in the development of a financially optimised strategy for timely seismic retrofitting.     

基于小波变换的钢筋混凝土结构损伤识别

钢筋混凝土结构在其服役期内,由于受到荷载、地震以及其他因素的作用,会发生损伤,从而威胁整个结构的安全。为了保证结构的安全,需要尽早发现结构的损伤,并且采取防范和修复措施。基于小波变换的多分辨率的特点,提出一种分层小波搜索的方法对结构损伤进行在线检测,确定损伤位置和损伤发生的时刻。通过对某一框架进行数值模拟试验验证可行的基础上,将此法应用于地震作用下钢筋混凝土框架的损伤识别,并与结构模型的模拟地震振动试验观测结果相对比,表明分析结果与试验观测较好吻合。     

扇形铅黏弹性阻尼器加固RC框架的抗震性能试验研究

针对钢筋混凝土框架结构梁柱节点震害严重的抗震问题,提出采用扇形铅黏弹性阻尼器加固框架结构的 方法,结合扇形阻尼器型式提出外包箱形钢板和外包U形钢板两种不同的加固连接方式。为研究扇形铅黏弹性阻 尼器加固框架的抗震性能,设计并制作了3榀框架试件,分别为空框架和两榀不同连接的扇形铅黏弹性阻尼器加 固框架,通过低周反复加载试验分析了其滞回性能、承载能力、刚度退化、耗能能力等参数。试验结果表明：采 用扇形铅黏弹性阻尼器加固的框架滞回曲线饱满、耗能能力强、加固效果良好;扇形铅黏弹性阻尼器为框架提供 了一定的抗侧刚度,提高了框架的水平承载能力,延缓了框架塑性铰的产生,使框架具有良好的耗能能力;外包 U形钢板和外包箱形钢板用于扇形铅黏弹性阻尼器与主体结构的连接都是有效的,这两种不同的连接方式对加固 框架的整体抗震性能影响不大。     

日本结构抗震加固的工程实例

本文由株式会社日建设计的结构设计部工程师具体介绍了一些地震加固工程实例。由于日本是多地震国家,不仅在结构设计时要求建筑物在地震后易于加固,而且在结构加固时也要求加固得足以抵抗将来可能发生的更强烈的地震,以保证建筑物的耐久性能。在日本,抗震理论和技术年复一年地提高,这里,主要介绍两种地震加固的方法—制振和隔震。实例1是采用含低屈服点钢材的吸能支撑(Energy Absorption Bracing,EAB)来进行地震加固的例子。该建筑建造于1970年,是一个64m高的型钢骨混凝土结构(Steel framed Re-inforced Concrete,SRC)。实例2是建于1920年的一所大学的小礼拜堂。这个2层的建筑高12.6m,由砖建成。在经过多方调查后,提出了三种方案来对其进行地震加固,最终选用了基底隔震技术来使得建筑上部的钢筋用量最小。实例3是一个国际儿童文献图书馆的改造工程,该图书馆成功地保留了原来建筑的历史价值,并且又增加了很多当代图书馆的新功能。在该工程中采用了基底隔震技术。     

Machine vision-based automated earthquake-induced drift ratio quantification for reinforced concrete columns

This paper presents a novel method for estimating the seismic peak interstory drift ratio (IDR) in reinforced concrete (RC) columns after an earthquake using surface crack image analysis. The quantitative representation of the complexity and irregularity of crack images in damaged RC columns is obtained through the consideration of the generalized fractal dimensions. The authors have compiled a comprehensive database consisting of 445 crack maps obtained from cyclic experiments conducted on 110 rectangular RC column specimens exhibiting double-curvature deformation mode. This database is utilized by the authors to develop and validate the proposed procedure. The research database contains a wide range of structural and geometric features. Five closed-form equations are developed with the objective of estimating the peak IDR experienced by the RC columns during a seismic event. The predictive equations are derived through the utilization of symbolic regression technique, with the input parameters varying according to the availability of columns characteristic parameters. Results reveal that generalized fractal dimensions, especially D₋₁, are strong vision-based indicator of damage in RC columns having correlation coefficients with IDR ranging from 0.82 to 0.92 across the considered plans. The seismic peak IDR obtained through the empirical equations can serve as the input engineering demand parameter (EDP) in the seismic loss estimation frameworks. This allows for the determination of the probability of exceeding damage states for structural and nonstructural components of concrete buildings. Finally, the practical implementation of the methodology is examined by its application to an actual case of a damaged column during the Kermanshah earthquake of magnitude 7.3 that occurred in 2017.     

6度区某既有框架-剪力墙结构小高层抗震鉴定实例

大量的震害表明,对既有建筑进行抗震鉴定并针对性地提出加固处理意见可以有效地减少地震所带来的损失。我国现行抗震鉴定标准仅要求从构造措施上对6度地区建筑物实施抗震鉴定,而未对抗震承载力验算提出硬性规定,与此同时,也未对小高层建筑的抗震鉴定方法予以规定。考虑到小高层建筑受力的特殊性以及不满足构造措施要求的6度区建筑物也可能满足抗震鉴定的要求,文章以前人研究为基础,采用两级鉴定法对6度地区某既有框架-剪力墙结构小高层建筑进行抗震鉴定,以便为类似工程处理提供参考。     

Fragility assessment of high‐rise reinforced concrete buildings considering the effects of shear wall contributions

The effect of shear wall configurations on seismic responses of high‐rise RC buildings is investigated in this paper using fragility analysis method. Four lower high‐rise RC buildings that have the same plan dimensions and height but are different in configurations in lateral force resisting systems, were firstly designed following the standard code procedure. To consider uncertainties in earthquake motions, 16 real ground motion pairs were selected and scaled, then applied orthogonally to the four RC building models during the Incremental Dynamic Analysis (IDA). Fragility relationships were therefore derived based on the IDA results for the three limit states including slight damage, moderate damage and collapse to show the probabilistic comparison of seismic responses among the four buildings in both x and y‐directions. It was observed that generally adding shear walls will improve buildings' seismic performance at all limit states. However, shear wall configuration also plays a significant role in seismic behavior of the lower high‐rise regular RC buildings' and internal shear walls are generally more effective than external shear walls in improving building's seismic resistance. Copyright © 2016 John Wiley & Sons, Ltd.     

预制自保温钢筋混凝土墙板加固震损框架试验研究

为了达到震后快速加固修复和建筑节能改造等综合加固改造目的,提出采用三明治式预制自保温钢筋混凝土墙板（PISW）对震损钢筋混凝土框架进行快速加固的方法。开展了4榀采用预制自保温钢筋混凝土墙板加固震损框架模型的低周往复加载试验,研究了预制自保温钢筋混凝土墙板与损伤框架之间的连接构造以及墙板配筋率对加固效果的影响,分析了试件的破坏特征、滞回性能、骨架曲线、耗能能力等。结果表明：采用预制自保温钢筋混凝土墙板加固方法可大幅度提高震损框架的承载能力;预制自保温钢筋混凝土墙板与损伤框架之间的界面强度是影响加固试件承载能力的主要因素;由于墙板破坏不充分,墙板配筋率的变化并未对承载力产生明显影响。基于试验研究结果提出了预制自保温钢筋混凝土墙板加固震损框架受剪承载力计算方法。     

Seismic response of semi‐active friction‐damped reinforced concrete structures with self‐variable stiffness

The influence of structural self‐variable stiffness and semi‐active friction dampers on the behavior of reinforced concrete (RC) buildings during strong earthquakes is discussed. A fully braced six‐story beamless RC frame is analyzed. The effect of concrete braces (with only constructive reinforcement) as a self‐variable mechanism is studied. It is shown that up to a certain limit the frame itself controls its behavior by adapting its dynamic characteristics in the real time of the earthquake. This self‐adaptation is achieved by autonomous disengagement of the braces under tension and their further nonlinear action under compression. The system has several levels of seismic adaptation, and it selects one of them for enhanced response to the given earthquake. However, when the limit is reached, further self‐adaptation of the frame becomes impossible. The occurrence of an earthquake of higher magnitude can then lead to disengagement of the concrete braces under compression, intensifying structural damage and even causing collapse. The use of semi‐active controlled friction dampers is proposed as a means of preventing the collapse of braces under compression, thereby enabling structures to withstand earthquakes. The forces in the friction dampers are regulated according to an optimal control algorithm. Modulation of the friction level in real time during the earthquake yields additional improvement of structural seismic behavior and obviates the need for retrofitting. Copyright © 2007 John Wiley & Sons, Ltd.     

隔震加固技术在框架结构加固工程中的应用

介绍了框架结构隔震加固的设计与施工流程,利用有限元软件Etabs9.5.0,选用EI-centro、Taft波作为地震动输入,对框架结构进行了动力时程分析。通过层间剪力、层间位移这两个隔震性能指标的对比分析,表明隔震结构有着明显的减震效果。采用叠层橡胶支座来进行隔震加固改造,施工作业面可限制在地下室内,上部结构不需处理即可满足提高一度设防的要求,且楼面的加速度反应减小,可以有效的保护室内仪器设施,提高建筑综合抗震防灾能力。建筑物隔震加固改造是一种安全、经济、简单、环保的技术手段,具有明显的经济效益和社会效益,有着广阔的应用空间。     

Collapse safety margin-oriented seismic retrofit strategy for corroded reinforced concrete frames using fibre reinforced plastics

Considering residual service life, this paper presents a collapse safety margin-oriented seismic retrofit strategy for corroded reinforced concrete (RC) frames using fibre reinforced plastics (FRP). With the assumed uniform corrosion model, corrosion-induced initial damage combined with subsequent earthquake-induced damage is identified by the multi-mode-based global damage model developed previously. The collapse-level earthquake intensity determined by incremental dynamic analyses (IDA) with the damage model and the maximum considered earthquake (MCE)-level intensity considering residual service life are combined to generate the time-variant collapse safety margin assessment of corroded RC structures. Based on this assessment, the collapse safety margin-oriented FRP seismic retrofit strategy is proposed and demonstrated on a 4-storey frame. The damage model originally developed for earthquake scenarios has also exhibited its rationality for characterising corrosion-induced initial damage and its influence on coupled damage development with subsequent earthquake excitation. Seismic retrofitting with FRP composites should consider the effects of the corrosion development stage, target collapse safety margin and residual service life. FRP retrofits can cause decreases in the MCE-level collapse probability and increases in the collapse resistance of corroded RC structures. Retrofitting carried out at different times achieves different efficiencies and different time-variant collapse safety margins within the residual service life.     

相邻RC框架结构地震碰撞过程模拟与初步分析

相邻建筑物碰撞是指地震作用下其间距无法满足相对位移要求时造成的侧向撞击,常常导致或加剧结构破坏。选取Hertz-damp接触单元模型,推导了考虑碰撞的结构动力方程,模拟了相邻钢筋混凝土（RC）框架结构地震碰撞过程。分析碰撞过程,并利用梁柱单元破坏指数的变化解释了相邻RC框架结构地震碰撞破坏机理,指出地震碰撞破坏作用不完全随防震缝宽度的增加而降低。     

采用不同减震结构体系的医疗建筑地震经济损失评估

建筑物在地震作用下的直接经济损失不仅来自于结构构件，而且来自于非结构构件和建筑内部物品的破坏。对于满足现行抗震设计规范要求的建筑物，非结构构件和建筑内部物品的破坏经常成为建筑物地震经济损失的主要来源。为此，以某医疗建筑为研究对象，采用底部隔震、增设屈曲约束支撑和增设摇摆墙等三种减震方案对其进行加固，通过对比原建筑和采用不同方案加固后的建筑在不同强度地震作用下的经济损失，研究不同减震结构体系对减轻建筑物地震经济损失的作用。分析结果表明，各减震方案均能有效减小结构的位移反应，隔震方案能同时有效地减小结构的加速度反应。由于所研究的医疗建筑在地震作用下的经济损失主要来自于医疗设备等加速度敏感型非结构构件，因此采用隔震方案在减小地震经济损失方面具有明显的优势。     

A model for earthquake risk management based on the life-cycle performance of structures

Over 50 years of design life, buildings are exposed to different magnitudes and frequencies of earthquakes that require consideration of life-cycle cost (LCC). The LCC entails quantifying the building performance under seismic hazard and investments throughout the life of the structures. Traditional LCC utilises probabilities of being in different damage states. However, for buildings with inherent irregularities (e.g. vertical irregularity and plan irregularity), these probabilities are not readily available. In this paper, a system-based approach, utilising fuzzy set theory, is used to quantify the possibility of being in different damage states. The analysis is limited to study the effect of seismic exposure on the building LCC. The proposed method is illustrated with two case studies, a six-storey reinforced concrete (RC) building located in Vancouver, Canada, and vulnerability of an urban centre with 1000 RC buildings. Furthermore, sensitivity analysis is carried out to highlight the impact of different building performance modifiers on the LCC.