Vulnerability assessment of a high‐rise building subjected to mainshock–aftershock sequences

Strong aftershocks have the potential to further aggravate the damage state of structures, and much less attention has been given to the seismic vulnerability of high‐rise buildings than that of low‐ to medium‐rise buildings. This study assesses the seismic vulnerability of a 32‐storey frame–core tube building by performing the incremental dynamic analysis on the material‐based three‐dimensional numerical model. A storey damage model based on the material damage is developed using the weighted average method. Eighteen recorded mainshock–aftershock sequences, whose mainshock records match the target spectrum, are selected. The results indicate that the developed stroey damage model can effectively reflect the additional damage induced by aftershocks. Strong aftershocks have high potential to change the location of weak storeys. Notably, shifts of weak storeys are observed in more than 30% of aftershocks with relative spectral acceleration of 0.8. As the mainshock‐induced damage state becomes more severe, the mainshock‐damaged building becomes increasingly fragile to the aftershock excitation and more sensitive to aftershock intensities. The probability of exceeding severe damage state increases from 35.3% to 62.1% due to the effects of strong aftershocks. The results in this study can provide supports to the seismic resilience assessment of this high‐rise building.     

A systems approach to flood vulnerability

Flood vulnerability is an internationally important problem with no easy solution. In this paper it is argued that vulnerability is an emergent output of interacting human and engineering components, and that to make further progress on usefully deploying the concept, a systems approach is needed. The existing state of the art in Flood Vulnerability Indices is blended with a constraints-based systems engineering approach called an Abstraction Hierarchy. Four existing towns were modelled using this approach, and the impact of a 1–200 year flood was assessed, by focusing on the key interactions within the model. As the flood waters progressively removed physical objects in the system, higher-level processes and functions became systematically degraded. Via this process, the modelled towns were revealed to be low on exposure, high on susceptibility, but low on resilience. This is one of eight vulnerability types possible. Different flood risk solutions can be associated with different vulnerability types. Comparing these outputs to real-life policy and practice reveals some interesting areas of mismatch.     

Making Room for the River

Abstract

Problem, research strategy, and findings: In this study we analyze plan integration for flood resilience in the city of Nijmegen, the site of the largest Room for the River project in The Netherlands. Little is known about the degree to which local and regional plans are coordinated with the national Room for the River program or about the cumulative influence of plans on flood vulnerability. To effectively investigate these issues, we use and build upon the Plan Integration for Resilience Scorecard (PIRS) concept and method, which analyzes the consistency and effects of networks of plans on community vulnerability. We expand the scope to include plans from multiple administrative scales and the focus to include environmental vulnerability. Using a three-phase evaluation process, we demonstrate that Room for the River policies are well integrated in Nijmegen’s network of plans, particularly with respect to flood safety and natural protection. However, we also find that policies at different administrative scales lack consistency in some places, some socially vulnerable neighborhoods receive comparatively little policy attention, and local plans often prioritize development over flood resilience, though higher tier plans sometimes make up for these policy gaps. Flood resilience is still finding its way in the Dutch planning system.

Takeaway for practice: The PIRS offers planning practitioners a method to assess how networks of plans influence community vulnerability and, as demonstrated in this analysis, to determine the degree to which plans at multiple administrative scales target the most physically, socially, and environmentally vulnerable geographic areas. It can be used to support the ambitious goals of a program like Room for the River and align them with local development priorities.     

Mapping and classification of direct flood impacts in the complex conditions of an urban environment. The case study of the 2014 flood in Athens,Greece

Urban flooding is a gradually increasing problem as the urban population expands into floodplains. In urban environments, flood vulnerability is significantly increased as a more concentrated population and assets makes flooding costly and challenging, in terms of impact estimation. This work focuses on mapping and classifying impacts after the catastrophic 2014 flood in Athens, Greece. The study proposes a method for classifying flood effects into four categories including: the natural and built environment, mobile objects and human population, organized in five classes of increasing severity, i.e. minor, weak, moderate, strong and extreme. Flood effects are grouped based on the qualitative nature of the recorded effects, allowing the development of an impact-severity map. Mapping of the 2014 flood effects indicated specific locations where the severity of impacts was distinctively higher than others, providing a holistic overview of the flood’s effects and highlighting the usefulness of the approach in future flood protection planning.     

基于承洪韧性的老旧住区更新规划 策略研究——以天津川府新村住区为例

针对当前城市中老旧住区面临的雨洪灾害日益严重的问题,梳理国内外有关承洪韧性的相关研究,探讨承洪韧性的内涵与作用,建立了城市老旧住区雨洪管理影响要素与承洪韧性的关联框架。根据城市老旧住区的基本特征和其中普遍存在的问题,从提升可浸区百分比、提升雨水贮存率,以及提升雨水利用率等方面提出了基于承洪韧性理念的城市老旧住区更新策略。再以天津川府新村为例,针对该住区现状存在的雨洪灾害问题,模拟验证了相关策略的实施效果。     

北京城市雨洪管理初步构想

城市化进程的加快使城市内产生了"水多"、"水少"、"水脏"等问题.单纯的建筑与小区雨水利用对设计标准内的降雨有很好的控制和利用效果,但对较大降雨和超标准降雨则难以应对.基于降雨产流、管网汇流和河道行洪的预报、监测与模拟的全面城市雨洪管理则是解决这一难题的重要措施.介绍了国内外城市雨洪管理的现状,针对北京城市雨洪管理存在的问题和不足,提出了北京城市雨洪管理的基本思路和需要进一步研究的关键问题,旨在推进北京城市雨洪管理的实施和"宜居城市"的建设.     

NbS在城市雨洪韧性规划中的应用研究

城市雨洪灾害的产生与气候变化、土地利用、防洪排涝基础设施空间布局等密切相关。大量研究证实,单一依靠市政改造雨水管网的传统做法工程成本高、改造难度大,实际效果不理想。而基于自然的解决方案(Nature-based Solutions,Nb S)倡导对生态系统的最小干预,将灰蓝绿基础设施有机结合,为城市雨洪韧性规划提供了一种新思路。采用“理论研究+应用案例”相结合的方法,首先分析了将Nb S理念应用到城市雨洪韧性规划中的切入点,提出Nb S视角下城市雨洪韧性规划的一些思考;其次,应用MIKE FLOOD模型,对场地雨洪风险进行评估;最后,结合应用案例特点,以堤防岸线、水系网络、水位管理为抓手,阐述了Nb S理念在城市雨洪韧性规划中的具体方案。结果表明,Nb S视角下的城市雨洪韧性规划方案具有可行性,以期共同推动Nb S实施行动。     

基于SD模型的绿色建筑项目系统脆弱性研究

绿色建筑项目系统脆弱性是隐藏于系统内部的属性之一,其对绿色建筑项目风险存在一定影响。研究绿色建筑项目系统脆弱性,进而推动绿色建筑的健康发展目的,以分析系统脆弱性驱动因素为核心内容:采用文献分析法对系统脆弱性驱动因素进行识别;通过G1赋权法确定各驱动因素的权重系数;基于敏感性、适应性和暴露性3个维度建立SD（System Dynamics）模型。通过对其中的6个常量型驱动因素进行系统动力学仿真分析,结果表明:对绿色建筑项目系统脆弱性影响显著的驱动因素为施工企业资质等级、设计积极程度和项目规模。拓展了绿色建筑项目系统脆弱性的驱动因素研究,为控制绿色建筑项目系统脆弱性指数提供理论依据。     

Bayesian modeling of flood control networks for failure cascade characterization and vulnerability assessment

This paper presents a Bayesian network model to assess the vulnerability of the flood control infrastructure and to simulate failure cascade based on the topological structure of flood control networks along with hydrological information gathered from sensors. Two measures are proposed to characterize the flood control network vulnerability and failure cascade: (a) node failure probability (NFP), which determines the failure likelihood of each network component under each scenario of rainfall event, and (b) failure cascade susceptibility, which captures the susceptibility of a network component to failure due to failure of other links. The proposed model was tested in both single watershed and multiple watershed scenarios in Harris County, Texas using historical data from three different flooding events, including Hurricane Harvey in 2017. The proposed model was able to identify the most vulnerable flood control network segments prone to flooding in the face of extreme rainfall. The framework and results furnish a new tool and insights to help decision‐makers to prioritize infrastructure enhancement investments and actions. The proposed Bayesian network modeling framework also enables simulation of failure cascades in flood control infrastructures, and thus could be used for scenario planning as well as near‐real‐time inundation forecasting to inform emergency response planning and operation, and hence improve the flood resilience of urban areas.     

A proactive and resilient seismic risk mitigation strategy for existing school buildings

Different methods and procedures have been developed to define prioritisation strategies of retrofit interventions aimed at reducing the seismic risk of school buildings on a large territorial scale. However, these approaches fail to demonstrate how risk analysis has been used successfully to quantitatively assess and select the optimal risk management decision. This article proposes innovative and useful metrics to measure the potential costs and benefits related to the prioritisation of retrofit intervention and the resilience of the analysed school system by directly integrating engineering, organisational, socio-economic and political aspects in the realm of seismic resilience assessment. Based on probabilistic risk assessments considering the new vulnerability of the prioritised school buildings, these measures could predict the expected economic and functional losses associated with a disastrous seismic event, as well as the possible post-disaster recovery of the system. In order to help decision-makers in selecting the optimal mitigation strategy with a multidisciplinary and multidimensional perspective, different political scenarios, the relative prioritisations of interventions and their intervention options are also defined. The proposed framework is demonstrated in a complex case study of 1,825 public schools in the Lima metropolitan area, Peru. Policymakers, planners and engineering professionals could benefit from results.     

美国路易斯安那州可持续海岸带总体规划研究

可持续海岸总体规划的提出对降低滨海城市灾害损失具有重大作用。路易斯安那州通过总结长期沿海减灾和恢复工作,提出通过制定可持续海岸总体规划降低沿海地区脆弱性,维持沿海工业和企业长期稳定可持续发展。该规划针对灾害的严重程度提出不同应对场景,通过土地开发与工程营建、降低洪水风险和减灾资金分配等措施,促进规划实施。规划中设计的适应性管理、建立动态资源数据库、海岸信息管理系统等减灾工具和方法,对我国综合防灾减灾规划有启示作用。     

Implementation of the floods directive in selected EU member states

To reduce the flood risk at European scale, the Floods Directive (FD) became into force in 2007. Each member state had transposed the directive in national laws and guidelines, generating a quite spotted situation. This work is intended to compare and briefly assess the implementation process on rivers in selected European countries by means of the available literature and a specific questionnaire. Different structures, methodologies and data conditions used for preliminary flood risk assessment, flood hazard maps, flood risk maps and flood risk management plans are here presented and analysed. To minimise the flood risk, the technical differences between the EU countries need to be reduced in the next implementation cycles of the FD.     

Prognose der Bauwerksschädigung unter Hochwassereinwirkung

Prognosis of building damage due to flood impact. Reliable prognoses of building damage caused by flood impact require realistic correlations between action and loss describing parameters. Due to the fact that commonly applied damage relationships between inundation level and loss are related to the costs for the different insurance sectors or usage classes (i.e. private housing), the required differentiation according to the parameters on the resistance side is still missing. The large scatter in the damage data has complicated the derivation of reliable general loss predictions and specific cost‐benefit analyses. On the basis of the August 2002 Saxony flood data base, a method to determine the structural damage of a single building or of the affected building stock for any given flood scenario is developed. Repeatedly observed damage patterns are transformed into a classification scheme of damage grades. With this tool, the structural damage of all damage cases can be analysed in a systematic way and related to the parameters describing flood impact. Vulnerability classes for the different building types are defined by using the data for determining characteristic ranges of damage expectation. Basic steps of the procedure are illustrated for a fictive data‐set, and subsequently applied to the existing database. As one of the main results, a new type of vulnerability function is proposed, describing the empirically‐based relationship between inundation height and the introduced damage grades D_i. With these vulnerability functions the damage distribution caused by the August 2002 flood can be reinterpreted for test areas with close agreement to the observed effects. A similar good prognosis could be achieved for the reported loss in monetary terms by correlating vulnerability class and impact parameter (inundation level) in specific loss functions. Thus, the prerequisites for the practical application of the procedure and presented tools are given.     

Die Sturzflut von Braunsbach – Ingenieuranalyse der Gebäudeschäden

The flash flood of Braunsbach – engineering analysis of the building damage At the end of May to the beginning of June, a series of extreme rainfall events occurred in the southern part of Germany, which triggered some severe flash floods with significant building damage in the affected municipalities. The devastating flash flood of May 29, 2016 in Braunsbach in the district Schwäbisch Hall in Baden‐Württemberg caused heavy structural damage to some of the approximately 130 affected buildings. The paper gives an overview of the building damages documented immediately after the event. The damages cases were classified and assessed using the evaluation system of the EDAC‐flood damage model developed at the Earthquake Damage Analysis Center (EDAC) of the Bauhaus‐Universität Weimar. The analysis illustrates the particularities of the damage patterns due to flash floods compared to conventional river floods.     

Quantifizierung der Schadenspotentiale infolge Erdbeben – Teil 1: Rekonstruktion des Bebens in der Schwäbischen Alb vom 03. September 1978

Assessment of damage and loss potentials due to earthquake (1): reconstruction of the “Albstadt” – quake in the Swabian Albs in September 03, 1978. Due to lack of strong earthquakes, there is almost no data or experience available concerning the behaviour and vulnerability of common buildings in German seismic zones. The consideration of their earthquake resistance or vulnerability is still outside the scope of official investigations. A scale is missing to calibrate results of seismic risk assessment and to prove their reliability. For these purposes, an outstanding importance has to be attested to the September 03, 1978 Earthquake in the Western Swabian Alb, the heaviest one in Germany over the last 50 years. The 1978 Albstadt earthquake provides an impression of the severity of design earthquakes (in lower range) defined by DIN 4149: 2005 for the highest zone 3. Due to the limited time elapsed since the quake, it can be assumed that the building inventory is comparable to the situation today and might be generalized to other communities in that zone today. The present study can be regarded as a continuation of research activities directed towards the assessment of damage and loss potentials in German cities initiated by Deutsches Forschungsnetzwerk Naturkatastrophen (DFNK), while introducing recently elaborated and more refined approaches. The detailed survey and documentation of damage cases provide the basis to test the applicability of the developed GIS‐based seismic risk assessment technologies to other seismic regions. For this purpose, the main damage zones and the distribution of mean damage grades in Albstadt/Tailfingen are reconstructed and the loss will be recalculated for the building inventory at the time of the quake in 1978. The vulnerability of building types is evaluated on the basis of the European Macroseismic Scale EMS‐98. The classification of EMS‐98 is used to transform the existing damage observations into a scheme of damage grades. In addition to the empirical approach, selected damage cases are examined by a recently developed evaluation tool for masonry structures, combining experience and analysis in a hybrid way to detect critical zones, as well as the extent and the level of damage. All results indicate a remarkable agreement with the reported situation.     

Development of building vulnerability functions in subsidence regions from empirical methods

The extraction of ores and minerals by underground mining often causes ground subsidence phenomena. In urban regions, these phenomena may induce small to severe damage to buildings. To evaluate this damage, several empirical and analytical methods have been developed in different countries. However, these methods are difficult to use and compare due to differences in the number of criteria used (from 1 to 12). Furthermore, the results provided by damage evaluation may be significantly different from one method to another. The present paper develops vulnerability functions based on a concept that has been applied in other areas, such as earthquake engineering, and that appears to be a more efficient way to assess building vulnerability in undermined cities. A methodology is described for calculating vulnerability functions in subsidence zones using empirical methods. The first part of the paper focuses on existing empirical methods for damage evaluation, and selected necessary improvements or modifications are justified. The second part focuses on the development of a building typology in subsidence zones and its application in the Lorraine region, where many villages are subject to subsidence problems due to iron-ore mining. The third section describes and discusses the adopted methodology for determining vulnerability and fragility functions or curves. Finally, vulnerability functions are tested and validated with a set of three subsidences that occurred in Lorraine between 1996 and 1999.     

基于InVEST模型的闽三角地区沿海脆弱性评估及响应策略

气候变化和城镇化建设使沿海地区面对自然灾害呈现出显著的脆弱性.以生态系统服务和权衡的综合评估模型的沿海脆弱性模块评价闽三角区域尺度的沿海脆弱性和人口风险,从中选取典型高风险的厦门市,从地理特征、气候胁迫和社会经济3个方面完善指标选取,基于模糊理论反映指标权重的模糊不确定性,细化厦门城市尺度的沿海脆弱性评价,分析模拟当前...     

基于耗能差指数和SIR模型的#br# 结构易损性及可恢复能力评估

传统结构地震易损性中结构地震响应指标对损伤反映不充分,且无法为结构震后可恢复性评估提供准确的初始损伤指标。针对上述不足和结构地震可恢复能力评估的需求,提出运用基于弹塑性耗能差的损伤指数进行结构地震易损性评价的方法。建立可推演出指定地震动强度和超越概率下的损伤指数的计算方法。利用SIR模型能够描述系统损伤和恢复动态演变过程的特点,提出基于该模型的单体建筑结构和区域建筑群的性能水平恢复函数模型及结构的恢复能力计算方法,从而表征建筑结构群体在地震激励下的“直接损伤 间接损伤 恢复”全过程。以单体结构和区域结构为算例进行易损性分析和震后可恢复性评估,结果表明：基于弹塑性耗能差的损伤指数具有真实可靠和机理明确的特点,在离散性和相关性方面均优于传统指标。SIR可恢复性能评估模型较常用恢复函数模型更为精准,简单高效且适合推广到区域建筑集群体当中,是对现有区域恢复性能评估框架的有益补充。     

Seismic vulnerability assessment of tilt-up concrete structures

This paper focuses on seismic vulnerability assessment for one-story tilt-up concrete structures. To capture the potential failure mechanisms, an analytical modelling approach using nonlinear properties is developed and verified with measured data from a shake table test documented in the literature. Nonlinear dynamic analyses using synthetic ground motions for Memphis, Tennessee, are performed to assess dynamic behaviour of the buildings. Then, probabilistic demand models for multiple limit states that represent potential failure mechanisms are developed with a Bayesian updating approach. These demand models are used in conjunction with appropriate capacity limits to develop fragility curves that provide a probabilistic measure of the seismic vulnerability of typical tilt-up concrete buildings. This study shows that the vulnerability of typical tilt-up structures in Mid-America is significant when seismic hazards are high. In addition, it is found that the aspect ratio of building geometry has a significant impact on the seismic performance and fragility estimates of tilt-up buildings.     

村镇建筑抗洪性能评价系统研究与开发

我国是洪水灾害多发国家,每年都有大量村镇建筑在洪水中严重损坏甚至倒塌,造成巨大生命和财产损失。因此,对村镇建筑抗洪性能进行深入系统的研究具有重要意义。本文首先介绍作者开发的村镇建筑抗洪性能评价系统AEFARUB的研究背景及构成,然后重点介绍各个模块的原理和特点。文中内容可供工程应用和进一步研究参考。