建筑结构可靠性的发展与鉴定概述

对结构可靠性理论发展进行了总结和分析。详细阐述了各发展阶段的发展过程及优缺点,并提出了保证结构可靠度的方法和对策,为提高我国结构可靠度的研究水平提供了发展思路。     

工程结构可靠性基本理论的发展与应用(1)

作者根据大量的文献,从结构可靠性基本理论和方法、结构体系可靠度、结构可靠度的Monte-Carlo模拟方法、结构承载能力与正常使用极限状态可靠度、结构疲劳和抗震可靠度、钢筋混凝土结构施工期和老化期可靠度六个方面,对结构可靠性理论和应用国内外研究的现状进行了概括性总结,以期为我国在这方面研究的进一步发展提供参考。本篇是其中的第一部分,主要介绍了结构可靠度基本理论方面的现状与发展。     

工程结构可靠性基本理论的发展与应用(2)

自20世纪20年代以来,工程结构可靠性理论和应用的研究已取得了重大进展。本文根据大量的文献,从结构可靠性基本理论和方法、结构体系可靠度、结构可靠度的Monte-Carlo模拟方法、结构承载能力与正常使用极限状态可靠度、结构疲劳和抗震可靠度、钢筋混凝土结构施工期和老化期可靠度六个方面,分三部分对结构可靠性理论和应用国内外研究的现状进行了概括性总结,以期为我国在这方面研究的进一步发展提供一个参考。本篇是其中的第二部分,主要介绍了结构承载能力和正常使用极限状态可靠度,以及结构疲劳可靠度研究和应用方面的发展。     

工程结构可靠性基本理论的发展与应用(3)

自20世纪20年代以来,工程结构可靠性理论和应用的研究已取得了重大进展。本文根据大量的文献,从结构可靠性基本理论和方法、结构体系可靠度、结构可靠度的Monte-Carlo模拟方法、结构承载能力与正常使用极限状态可靠度、结构疲劳和抗震可靠度、钢筋混凝土结构施工期和老化期可靠度六个方面,分三部分对结构可靠性理论和应用国内外研究的现状进行了概括性总结,以期为我国在这方面研究的进一步发展提供一个参考。本篇是其中的第三部分,主要介绍了结构抗震可靠度,以及钢筋混凝土结构施工期和老化期可靠度研究和应用的发展。     

基于整体承载极限状态的钢结构可靠度设计方法及其在门式钢刚架设计中的应用

本文提出了基于整体承载极限状态的钢结构可靠度设计思路。这种思路建立在钢结构整体非线性分析和验算的基础上,并确保结构整体而非构件的可靠度水平,使结构整体的实际可靠度水平尽可能地接近于设计的目标值。本文针对门式钢刚架结构建立了一套实现这种设计的方法,包括结构整体非线性分析、结构体系可靠度计算以及实用的设计表达式。通过三个门式钢刚架结构设计实例比较了传统的构件设计方法,不考虑体系可靠度的整体承载极限状态设计方法和本文考虑体系可靠度的整体承载极限状态设计方法的设计结果,说明本文所提出设计思想的先进性。     

抗滑桩加固工程的体系可靠度及其计算模型

针对当前边坡加固工程抗滑桩可靠性计算中存在的考虑因素偏少的问题,提出了抗滑桩体系可靠度的概念及其计算模型。以系统工程理论为依据对影响抗滑桩结构安全的不确定性因素进行了分析,建立了边坡加固工程抗滑桩体系的系统模型并进行了分类。以可靠性工程理论对抗滑桩体系的可靠度进行了定义,并逐级建立了各类抗滑桩体系的可靠性计算模型,并以算例示范了该模型的应用。抗滑桩体系可靠度的概念及其计算模型全面反映了抗滑桩加固体系安全的不确定性,有助于对抗滑桩加固体系安全机理及事故发生机制的全面理解,对提高抗滑桩加固工程的设计可靠性有现实意义。     

复合基础可靠性分析在桩基础加固中的应用

本文运用结构可靠度理论,同时结合一个结构增层的工程实例,对复合基础极限承载力进行了可靠性分析,并对基础进行可靠性设计。     

按加拿大抗震规范设计的框架的可靠度及其应用

NBCC加拿大建筑规范(1995版)近来更新为2005版。它在抗震方面做了很大修正,并说明了基本原理。但是,两种版本均没有按抗震规定定量评估结构的可靠度,也没有提出能校准地震作用(假如有)设计值的目标可靠度。以按规范设计的6种抗弯框架为例,进行了结构的可靠度评估。该评估采用延性方法,将结果与用美国SAC工程中采用的方法所得的结果进行比较,二者所得的可靠度吻合较好。依据NBCC两种版本设计的框架的可靠度没有变化。举例说明了能校准地震作用设计值并获得目标可靠度的延性方法的使用过程,考虑了初始损伤和倒塌。结果表明:延性因子,抗震设计水平取决于考虑初始损伤或倒塌的目标可靠度。     

抗震结构可靠度分析及其应用

对抗震结构可靠度理论进行了分析和研究，并结合可靠度应用，介绍了在罕遇地震时用位移控制结构的抗震能力，平面规则性超限工程的设计和底部框架抗震墙房屋的抗震结构可靠度的研究和应用。     

建筑结构的可靠性研究分析

建筑结构的可靠性是设计与施工过程中需要综合考虑的因素,其安全性、适用性和耐久性都反映了结构的实际需求。建筑结构的可靠性可以用可靠度来衡量,采用先集中、后全面的方法适当地提高可靠度,对于建筑结构的可靠性有实质性的作用和现实意义。建筑物的可靠性受到多方面因素的影响,合理利用这些影响因素可以提高建筑结构的可靠性。     

Bridge life-cycle performance and cost: analysis,prediction, optimisation and decision-making

The development of a generalised framework for assessing bridge life-cycle performance and cost, with emphasis on analysis, prediction, optimisation and decision-making under uncertainty, is briefly addressed. The central issue underlying the importance of the life-cycle approach to bridge engineering is the need for a rational basis for making informed decisions regarding design, construction, inspection, monitoring, maintenance, repair, rehabilitation, replacement and management of bridges under uncertainty which is carried out by using multi-objective optimisation procedures that balance conflicting criteria such as performance and cost. A number of significant developments are summarised, including time-variant reliability, risk, resilience, and sustainability of bridges, bridge transportation networks and interdependent infrastructure systems. Furthermore, the effects of climate change on the probabilistic life-cycle performance assessment of highway bridges are addressed. Moreover, integration of SHM and updating in bridge management and probabilistic life-cycle optimisation considering multi-attribute utility and risk attitudes are presented.     

高性能结构抗多次多种灾害全寿命性能分析与设计理论研究进展

为促进高性能结构抗多次多种灾害全寿命性能设计理论研究在我国的发展,详细介绍了该领域的国内外研究现状并建立了其基本研究框架。对高性能结构在全寿命周期内可能遭受的多种灾害单独作用和联合作用的发生概率模型的研究成果进行了阐述,以碳化腐蚀作用和风致疲劳作用为例,论述了在结构全寿命周期内由环境作用引起材料及构件退化的时变模型研究现状,为开展多次多种灾害作用下高性能结构的全寿命性能分析研究提供了方向,并系统介绍了多种灾害作用下结构易损性分析方法和考虑灾害损失成本的结构全寿命抗灾性能优化设计方法的研究进展。基于全寿命周期的结构抗多次多种灾害性能设计方法,能够合理地解决传统设计方法中未考虑多种灾害联合作用和结构性能退化问题,对于建筑结构设计领域的发展具有重要意义。     

Life-cycle reliability assessment of reinforced concrete bridges under multiple hazards

This paper proposes a novel probabilistic methodology for estimating the life-cycle reliability of existing reinforced concrete (RC) bridges under multiple hazards. The life-cycle reliability of an RC bridge pier under seismic and airborne chloride hazards is compared to that of a bridge girder under traffic and airborne chloride hazards. When conducting a life-cycle reliability assessment of existing RC bridges, observational data from inspections can provide the corrosion level in reinforcement steel. Random variables related with the prediction of time-variant steel weight loss can be updated based on the inspection results using Sequential Monte Carlo Simulation (SMCS). This paper presents a novel procedure for identifying the hazards that most threaten the structural safety of existing RC bridges, as well as the structural components with the lowest reliability when these bridges are exposed to multiple hazards. The proposed approach, using inspection results associated with steel weight loss, provides a rational reliability assessment framework that allows comparison between the life-cycle reliabilities of bridge components under multiple hazards, helping the prioritisation of maintenance actions. The effect of the number of inspection locations on the updated reliability is considered by incorporating the spatial steel corrosion distribution. An illustrative example is provided of applying the proposed life-cyle reliability assessment to a hypothetical RC bridge under multiple hazards.     

Generalized bridge network performance analysis with correlation and time-variant reliability

A novel approach and framework for the analysis of bridge networks is presented. The goal of the analysis is to assess the life-cycle performance of the network and its time-variant reliability. The proposed approach combines three important features that determine its ability to estimate with accuracy and robustness the reliability of a network along its life-cycle.The first one is that the reliability of the individual bridges is modeled as time-variant, due to the deterioration of their structural components. The network performance analysis is repeated for several time instants, with the relative reliability of the bridges. Therefore, the network performance indicators are also time-variant. In this way, the proposed procedure can be used as a basic tool for maintenance planning at the network level.The second asset is that the proposed framework takes into account complex (i.e. “generalized”) network layouts, not necessarily describable using series, parallel or series-parallel models. In fact, when all the possible traffic flows in a network and all the possible trip origins and destinations are considered, it is not feasible, in general, to model the network with a simple scheme. In the present paper, techniques derived from transportation engineering for the traffic flow distribution and assignment are used.The third feature is that the proposed approach considers a correlation structure among the states (in/out of service) of the various bridges of the network. In fact, bridges associated with the same network are likely to share similar characteristics and external loads. Therefore, a correlation structure for the service state of individual bridges is estimated and implemented in the analysis.A case study involving a transportation network with fourteen bridges is presented as a numerical application.     

Life-cycle reliability analysis of shield tunnels in coastal regions: emphasis on flexural performance of deteriorating segmental linings

In contrast to reinforced concrete (RC) structures on land, RC shield tunnels in coastal regions deteriorate rapidly after their construction because of the combined effects of multiple mechanical and environmental stressors. In this paper, by considering the coastal hazards associated with chloride and the impacts of hydrostatic pressure, a novel approach is presented to estimate the life-cycle structural performance of a shield tunnel that has undergone deterioration due to chloride-induced steel corrosion. Deterioration processes in segmental linings are investigated via corrosion-accelerated experiments on individual segments, and the combined effects of corrosive agents and loads are emphasized. Monte Carlo simulation is used to estimate the time-variant failure probability of shield tunnels in a marine environment. In an illustrative example, the effects of structural location, hydrostatic pressure and material properties on the life-cycle reliability of shield tunnels are investigated.     

Integration of structural health monitoring in a system performance based life-cycle bridge management framework

In this paper, an approach for integrating the information obtained from structural health monitoring in a life-cycle bridge management framework is proposed. The framework is developed on the basis of life-cycle system performance concepts that are also presented in this paper. The performance of the bridge is quantified by incorporating prior knowledge and information obtained from structural health monitoring using Bayesian updating concepts. This performance is predicted in the future using extreme value statistics. Advanced modelling tools and techniques are used for the lifetime reliability computations, including incremental nonlinear finite element analyses, quadratic response surface modelling using design of experiments concepts, and Latin hypercube sampling, among other techniques. The methodology is illustrated on an existing bridge in the state of Wisconsin.     

Life-cycle performance,management, and optimisation of structural systems under uncertainty: accomplishments and challenges 1

Our knowledge to model, analyse, design, maintain, monitor, manage, predict and optimise the life-cycle performance of structures and infrastructures under uncertainty is continually growing. However, in many countries, including the United States, the civil infrastructure is no longer within desired levels of performance and safety. Decisions regarding civil infrastructure systems should be supported by an integrated reliability-based life-cycle multi-objective optimisation framework by considering, among other factors, the likelihood of successful performance and the total expected cost accrued over the entire life-cycle. The primary objective of this paper is to highlight recent accomplishments in the life-cycle performance assessment, maintenance, monitoring, management and optimisation of structural systems under uncertainty. Challenges are also identified.     

Stochastic dependency in life-cycle cost analysis of multi-component structures

It is crucial to assure that civil engineering structures can operate properly and safely, as damages during the service life may lead to catastrophic loss of property, fatalities and long-term consequences. The approaches for structural management through a life-cycle cost analysis need to address explicitly the dependencies between elements. The evaluation of the life-cycle maintenance cost of structures in this article considers stochastic, degradation and economic dependencies. A new approach to include stochastic and degradation dependencies, structural redundancy and load redistribution in structural management is developed herein. The proposed model uses the fault tree analysis and the conditional probabilities to take into account stochastic dependencies between the structural elements. The degradation consequences are evaluated and a method is proposed to account for load redistribution. Also, a practical formulation to approximate the reliability of systems formed by interrelated components is proposed, by the mean of a redundancy factor that can be computed by structural analysis. The proposed approach provides effective optimal maintenance decisions for civil engineering structures by considering the interaction between elements.     

Influence of the exposure scenario and spatial correlation on the probabilistic life-cycle seismic performance of deteriorating RC frames

The probabilistic life-cycle seismic performance of reinforced concrete (RC) frames under chloride-induced corrosion is investigated considering the influence of the environmental aggressiveness and exposure scenario and the role of spatial correlation of the random variables. Chloride ingress and corrosion damage are described at cross-sectional level by two-dimensional concentration maps and damage indices. At the structural level, the seismic performance is evaluated in terms of lateral load response of the deteriorating structural system by means of time-variant non-linear analysis over the structural lifetime. The uncertainties involved in the problem are taken into account in probabilistic terms by Monte Carlo simulation. The procedure is applied to life-cycle assessment of a three-storey RC frame under different exposure scenarios, defined by varying both the concentration level and the spatial distribution of chlorides on the external surface of the columns, as well as different correlation levels of the random variables involved in the probabilistic analysis.     

一种改进的工程结构全寿命设计理论指标体系

以结构耐久性为主线，对现有工程结构全寿命设计理论框架进行重组，将结构的全寿命设计目标总结为可靠性目标和可持续性目标两方面，建立了包含安全性、适用性、耐久性、经济影响、环境影响和社会影响等设计目标的全寿命设计体系，并确定了基于结构动态性能的全寿命设计思路。通过建立结构可持续发展指标，解决了现有全寿命设计理论中概念模糊和指标重复的问题，并完善了全寿命成本的内涵。改进后的全寿命设计理论指标体系具有更为完善合理的构架，能够广泛适应各种结构类型和使用情况。