核电厂地震概率风险评估研究综述

日本福岛核事故之后,核电厂抗震安全评估受到广泛关注。地震概率风险评估方法是核电厂抗震安全评估方法之一。该文针对地震概率风险评估方法进展做了全面综述：首先介绍核工程领域地震概率风险评估方法的发展历史;并总结核电厂地震概率风险评估方法的基本原理和研究进展;然后论述三种改进的地震概率风险评估方法：基于SMA的地震概率风险评估方法、基于性能的概率地震风险评估方法和先进的地震概率风险评估方法;最后对全文做了总结和展望。     

基于故障树和贝叶斯网络的仓储类建筑火灾风险评估

以降低仓储类建筑火灾风险为目的,通过分析影响仓储类建筑火灾发生原因,分析顶层事件与基层事件之间自上而下的因果关系,建立故障树,并将其映射到贝叶斯网络中,通过计算得出事件发生的先验和后验概率,并将两者有效的联系起来。给出各事件发生的重要度指标有结构指标、概率指标和关键指标,分别进行定量分析指出仓储类建筑最有可能存在的风险。文章以2010—2020年十年期间仓储类建筑火灾发生案例为样本对本文提出的模型进行验证。检验结果:文章提出贝叶斯网络模型能够有效评估仓储类建筑风险等级并降低火灾事故发生。     

Performance-based seismic fragility analysis of retaining walls based on the probability density evolution method

Seismic fragility analysis is an efficient way to study the seismic behaviour and performance of structures under the excitation of earthquakes of varying intensity, and an essential part of the seismic risk assessment of structures. A recently developed dynamic reliability methodology, the probability density evolution method (PDEM), is proposed for the dynamic reliability and seismic fragility analysis of a retaining wall. The PDEM can obtain an instantaneous probability density function of the seismic responses and easily acquire the seismic reliability of the structural system. An important advantage of the PDEM is its high efficiency relative to that of the Monte Carlo simulation method, which is often used in the reliability and fragility analysis of structures. The present study uses a typical gravity retaining wall to illustrate stochastic seismic responses and fragility curves that can be obtained by the PDEM. The combined uncertainties of the seismic force and soil properties are explicitly and systematically modelled by stochastic ground motions and random variables respectively. The performance of the retaining wall is analysed for different acceptable levels of backfill settlement. Additionally, seismic fragility curves are constructed without assuming the distribution of the seismic response.     

地铁隧道施工坍塌风险耦合机理研究

通过对我国2004—2018年间71例地铁隧道施工坍塌事故案例研究,发现地铁建设过程中出现的一系列微小的、不可预见的风险因子与风险主体状态及风险响应机制间存在着交互耦合关系,这些耦合作用使得风险系统所积蓄的风险能量突破安全阈值,从而导致安全事故的发生。针对上述安全事故成因分析,以城市地铁隧道施工坍塌风险耦合机理为研究对象,基于PSR-IAHP模型,分析地铁隧道施工坍塌事故发生的致因因子(P)、风险主体所处的状态(S)、风险管理响应(R)三者间的动态变化和作用机理,构建了地铁隧道施工坍塌风险耦合体系并进行了权重分析和计算。并结合灰色关联分析,以坍塌事故发生次数为特征指标,以风险耦合体系的11个指标为因素序列,以灰色关联度计算为基础,提出风险耦合度模型并进行计算。研究表明:影响地铁隧道坍塌事故发生的3个子系统及各因素序列间确实存在耦合作用,且多为“强耦合”,该研究结果可为城市地铁隧道施工坍塌风险断层控制提供理论基础。     

西江引水工程的风险评估与管理

以西江引水工程为例,根据风险评估流程,对该工程的主要风险进行了风险识别、风险分析和风险评估,最后针对关键节点的风险控制提出了一些建议,以最大程度地减小工程中风险事故发生率以及事故造成的损失。     

大型公共建筑风险特性分析

运用系统科学的思想和方法,将大型公共建筑作为一个系统,其风险由可靠性风险、安全性风险和可持续发展性风险共同构成。三者同时存在,共同作用。可靠性风险导致系统可靠性不足;安全性风险源于系统可靠性不足和安全性风险源;可持续发展性风险是可靠性和安全性风险在环境、社会系统中的长期体现。大型公共建筑的风险具有来源众多、关系复杂、不确定性高、影响巨大的特点。通过建立风险空间模型,用空间向量对风险状态进行描述,提出了风险安全空间的概念。风险的函数关系证明:降低大型公共建筑风险的关键在于提高系统可靠性。     

基于故障树和贝叶斯网络的建筑施工火灾风险评价

针对建筑施工现场频繁发生的火灾事故,将这一事故作为顶事件并分析导致顶事件发生的基本事件,构建故障树,表示出各基本事件与顶事件之间的逻辑关系。再将故障树转化成贝叶斯网络模型,通过贝叶斯网络的推理能力计算出顶事件发生的概率和各基本事件的后验概率。计算出各个基本事件的结构重要度、概率重要度、关键重要度,分别对三类重要度进行排序,定量地评估建筑施工火灾风险发生的可能性,找出最薄弱的环节,有针对性地指导现场施工。并引用案例数据计算施工过程中火灾事故的风险值,证明了将故障树与贝叶斯网络模型结合分析建筑施工安全风险这一方法的有效性和简便性,找出最能影响顶事件发生的风险因素,以及最容易降低概率的风险因素来更好地指导施工,将火灾风险降低到最小。     

Developments in the management of flood defences and hydraulic infrastructure in the Netherlands

This article highlights recent developments in flood risk management in the Netherlands and presents approaches for reliability analysis and asset management for flood defences and hydraulic infrastructure. The functioning of this infrastructure is of great importance for the country as large parts of it are prone to flooding. Based on a nationwide flood risk assessment, new safety standards for flood defences have been derived in the form of maximal acceptable failure probabilities. A framework for the reliability-based analysis of the performance of hydraulic infrastructure is introduced. Within this context, various challenges are discussed, such as the dynamic nature of loads, resistance and reliability requirements over time. Various case studies are presented to highlight advances and challenges in various application fields. The first case illustrates how structural health monitoring contributes to a better characterisation of the reliability of the defences and how innovative measures can enhance the reliability. The second case discusses how the river system can be managed in the context of the new safety standards. The third case shows how upgrades and reinforcements of hydraulic structures can be evaluated taking into account (uncertain) future developments, such as sea level rise.     

Structural analysis and design of sandwich panels with cold-formed steel facings

Superior structural efficiency, ease of erection, mass-production capabilities and thermal-insulation qualities are making sandwich panels with flat or thin-walled cold-formed steel facings and rigid foamed insulating core increasingly popular as enclosures for system buildings. In this paper the structural behavior — including flexural stresses, deflections, vibration and thermal stresses — is presented, summarizing more than two decades of research. Methods used are analytical (boundary-value approaches), numerical (finite-strip, finite-layer, finite-prism approaches) and experimental (full-scale testing). Key equations are formulated, and results by different methods are compared. Design guidelines are also suggested.     

预先危险性分析新方法的研究

阐述了危险性识别的原则和方法,进行了危险性等级的划分,详细介绍了可靠性分配理论与FTA法相结合在危险性预先分析中的应用,提出了危险性的控制方法,以促进预先危险性分析新方法的研究。     

Problems with the Moscow office

When the new Office Building for the United States Embassy in Moscow was in the final construction stage, visible defects caused work on the building to be suspended; a detailed structural analysis was then carried out by the NBS Center for Building Technology. Its report highlights the problems that can arise both with a structural design — such as guarding against buckling and progressive collapse — and with the detailed execution of that design.     

基于安全学原理的大跨浅埋隧道施工风险辨识

为了有效地消除和减少隧道施工过程带来的安全隐患,基于安全系统工程理论对大跨度浅埋深隧道施工风险进行了分析。以某典型大跨度浅埋隧道作为工程背景,运用事故致因理论对该隧道进行风险分析,绘制大跨度浅埋深隧道施工潜在危害鱼刺图。分析结果表明,大跨度浅埋隧道施工过程中存在七项潜在风险,分别为:围岩失稳、塌方、滑坡、超挖、初砌破损漏水、爆破和爆炸事故以及交通运输事故。针对围岩失稳这一风险极高的事故,选取故障树分析法对诱发此类事故的因素进行深入探讨。结果表明,做好地质探测工作、加强支护以及合理的爆破方式可有效避免该类事故。采取相同方法对其余六种风险因素也进行了分析,并提出了合理的对策措施。     

聚氨酯生产工艺危险性分析

以某聚氨酯厂为例,运用数学方法对生产场所建立了层次分析模型,并对危险因素的严重程度进行了分析,得出各个危险因素对整个系统影响的危险性权重,列出危险性较大的几个危险因素,另外采用事故树分析法对储存场所发生事故的各个基本原因事件进行结构重要度计算,得出了基本原因事件的结构重要度排序。     

基于n维等效方法的岩质边坡楔体稳定体系可靠度分析

 提出岩质边坡楔体稳定体系可靠度分析的n维等效方法,建立考虑多失效模式相关的楔体稳定体系可靠度分析的概率故障树模型。采用四参数b 分布来描述可靠度分析中基本随机变量的分布。最后采用n维等效方法计算楔体稳定体系可靠度,并着重分析随机变量敏感性分析的3个层次及不同层次上的可靠度对基本随机变量的敏感性。结果表明,n维等效方法计算的楔体体系失效概率均在Cornell简单上下限法的范围内,它能够有效地评价楔体体系可靠度。概率故障树模型能够清晰直观地模拟多失效模式相关的楔体体系可靠度问题,忽略失效模式间的相关性将会明显高估楔体体系失效概率。此外,黏聚力和内摩擦角之间的负相关性对边坡的可靠度具有有利的影响。随机变量敏感性分为单一极限状态方程、单一失效模式以及体系可靠度3个不同的层次,在研究随机变量敏感性时必须明确相应的分析层次。水压力和结构面产状的敏感因子较大,因此布置良好的边坡排水系统以及进行详细的地质勘测工作是提高楔体可靠度有效的方法。研究成果为边坡风险分析奠定了一定的基础。     

Structural steel and plane frame assemblies under fire action

By means of series of tests carried out on simply supported beams of standard rolled sections subjected to bending, fully analytically formulated calculation values were derived for the temperature-dependent stress-strain relationships of structural steel under fire action from normal temperature to 1000 °C.

Systematic series of investigations carried out on frame assemblies made up from rolled sections with high scale accuracy revealed the characteristic parameters influencing the critical temperatures. The analyses showed good-to-excellent agreement both for the temperature-displacement curves and for the critical temperatures, so that the integrity of the stress-strain relationships could also be verified for combined bending and compressive stress states and for stability-endangered assemblies.

The knowledge gained by the of experiment and computation furnished — in generalized terms — a basic concept for the simple and uniform assessment of the resistance to fire action of single elements and whole assemblies of structural steel subject mainly to bending stresses or endangered in stability. This allows the collapse temperatures of uniformly heated systems to be determined as a function of load utilization factor and system slenderness. These major parameters — load utilization factor and system slenderness ratio — are normal temperature design characteristics and can be determined using conventional methods.     

Load testing, structural reliability and test evaluation

A brief review of the history and types of load testing is followed by an examination of the effects of load test and other information on structural reliability. Two aspects are studied. (1) Multi-mode proof testing is posed as a system relability problem with one or more inequality conditions on structural performance. After-test reliability can then be found using standard system reliability methods from the reliability of the system augmented in “series” with the test mode, divided by the reliability in the test mode alone. (2) Test evaluation procedures for several applications are analysed using simulation of destructive sample tests, including strength uncertainty discoverable by testing and other non-test uncertainties in strength and loading. Evaluation rules are found to have a significant effect on the achieved reliability of test-based design.     

涉冬奥会场馆外工业场所火灾风险预警指标

为了预防冬奥会场馆外工业场所火灾事故,开展重点场所和关键设施火灾风险识别,研究多因素综合风险评估指标体系。通过典型事故案例统计分析和现场火灾隐患识别排查,确定了以涉氨制冷场所、发电厂、物流仓储企业为主的重点场所和关键设施的风险点;基于风险理论从场所固有火灾风险、风险减缓措施和现实风险角度,构建了冬奥敏感度、区域特征、建筑特性、消防设施状况和消防安全管理、外部救援力量为主的多因素综合风险评估指标体系,采用风险指数分级法确定风险指标重要度。研究表明：该多因素火灾风险评估指标体系实现了关键风险因素的动态数据获取和定量化,具有多源风险识别和动态研判作用,可较客观地提前预警影响冬奥会的重大工业火灾风险。     

极罕遇地震作用下建筑结构一致风险抗倒塌设计方法研究

结合当前国际上以“抗倒塌”为目标进行地震动参数区划和以“一致倒塌风险”为设防目标进行结构抗震设计的发展趋势,针对我国现行建筑抗震设计规范体系中抗倒塌能力评估的局限性,建议了四种一致风险抗倒塌设计方法,详细介绍了四种方法的评价指标与计算过程。考虑极罕遇地震作用,基于极罕遇地震一致风险谱对地震动记录进行了挑选与调幅。以RC框-剪结构作为典型案例,采用四种抗倒塌设计方法进行验算,结果表明：同时考虑地震危险性与结构不确定性影响的全概率方法验算未通过,其余验算方法均通过,这说明了忽略结构所在场地危险性影响会造成结构倒塌性能评估的不准确性,未考虑结构体系多种不确定性影响会高估结构的抗倒塌性能,因此有必要推行“一致风险”的结构设计理念。     

Risk based structural safety methods in context

Structural reliability calculations are now recognised by many as only one part of the assessment of structural safety. They provide partial evidence about the total problem which has to be integrated with other evidence to support decision making. It is proposed that a ‘holistic’ systems view based on a clear understanding of process is required. The model consists of interacting processes arranged in a hierarchy of differing levels of precision of definition and scope. The various attributes of each process are outlined under the generic headings of ‘who, what, why, where, when and how’. The ‘how’ attributes of a process which are important in the control of a process are hazard and risk. It is suggested that Interval Probability Theory is a suitable measure of the evidence that a process is being and will be managed to a successful conclusion. This can be combined with structural reliability predictions to give bounds on the evidence about the success of the total process which covers all foreseeable aspects of the uncertainty.     

坍塌事故风险演化复杂网络模型及消减对策研究

为预防坍塌事故,促进工程建设安全,采用事故案例分析法从116起较大及以上坍塌事故中识别出76个风险,提取出157条事故链,构建坍塌事故风险演化网络（CREN）模型;运用Pajek分析拓扑特性以明确坍塌事故风险演化规律;基于免疫理论对CREN的网络效率进行仿真,明确最优免疫策略和关键风险点;根据分析结果为坍塌事故的预防和风险消减提出针对性对策。研究结果表明:CREN具有无标度和小世界特性;最优免疫策略是DC免疫策略;控制违章作业子系统可使CREN网络效率降低近40%;坍塌事故是多种类型坍塌事故衍生的结果。