工程结构在多灾害耦合作用下的研究进展

我国地处亚欧板块、太平洋板块和印度洋板块之间，且疆域辽阔、海岸线绵长，这就自然形成了我国地震、强风和降雨等自然灾害频发。工程结构，包括高层建筑、村镇低矮房屋建筑群、输电塔线体系等生命线工程，在其全寿命周期内会遭受地震、强风和降雨等多种灾害的单独或同时作用。传统设计方法基于最不利荷载对结构进行设计，忽略了多种灾害耦合作用对结构全寿命周期抗灾性能的影响。文章总结了该课题组近年来在多灾害研究领域所取得的主要成果，包括：①根据中国强震台网中心和中国气象局数据中心提供的地震、风和降水数据，开展了极端事件单独作用和耦合作用的危险性分析；同时，提出了基于Copula函数的联合概率模型分析方法；②提出工程结构在多种灾害耦合作用下的性能评估和荷载修正系数计算方法；③开展了高层建筑在地震和强风单独作用以及同时作用下的风险分析及荷载修正系数计算；进行了村镇低矮房屋在地震和洪水耦合作用下的风险分析；对风雨耦合作用下的输电塔线体系进行了易损性分析。结果表明：①在考虑灾害发生概率时，不同灾害(例如，地震、强风和降雨)同时作用对结构性能评估具有显著影响；②由本文方法计算的荷载组合系数均不小于规范值，建议对现行规范中地震和风荷载的设计强度进行适当修正。因此，在对工程结构进行抗多灾耦合作用的性能分析和设计方法研究时，应综合考虑多种灾害的耦合效应。     

材料劣化的钢筋混凝土桥梁抗震性能

混凝土耐久性下降体现在材料性能的退化上,而材料性能的退化必然会导致桥梁结构抗震性能的降低,探究材料劣化的钢筋混凝土桥梁的抗震性能,对于提高桥梁的安全性和可靠性具有重要意义。结合项目拟以某三跨RC梁桥为例,采用ANSYS有限元程序,构建考虑冻融、氯盐等环境因子的三跨RC梁桥整体模型,对其在相同的地震作用下,进行非线性程本构关系的数值模拟,并对其在全寿命周期内的动力反应进行数值模拟,并将其与相应的受力、变形进行比较,最终得出:由于RC梁桥的材料退化,其抗震能力将进一步减弱,因此,需要在设计与施工中给予充分的关注。     

建筑全寿命周期费用分析研究现状及展望

全寿命周期费用分析方法是基于工程经济学和价值工程理论,应用系统思想对建设项目进行分析研究的一种有效方法。回顾了全寿命周期费用分析方法的发展历史,综述了全寿命周期费用应用领域、分析步骤、费用分解结构及费用分析方法的研究现状;最后对全寿命周期费用分析进行展望。     

考虑建筑非主体结构地震直接损失模糊综合评估

基于性能的抗震设计是结构抗震设计的发展趋势。而基于性能抗震设计的基本原理就是对不同结构选择合理的设计方案使结构的整个使用周期内的总费用最低。对结构全寿命周期总费用中结构地震直接损失费用评估研究现状进行了总结。此基础上完善了结构地震直接损失评估方法,并提出基于模糊综合评价法的结果地震直接损失费用评估模型。     

基于全寿命周期的变电站设计集成研究

作为重要的公共设施,变电站的设计不仅要考虑其全寿命周期,也应当体现科学发展、可持续发展、保护环境的理念和工程对社会、历史负责的精神。文章提出了这样的设计集成模型,即用工程系统结构维和设计目标结构维的映射构成变电站全寿命周期设计集成技术系统的模型和框架。作为国家电网资产全寿命周期管理研究的子课题,文章研究应当能对变电站等重要公共设施的设计管理工作起到一定的指导和借鉴作用。     

全寿命周期理念下的桥梁设计探讨

全寿命周期理念是将设计的时间参数拓展到桥梁的整个生命周期,统筹考虑设计、施工、运营和养护管理各个环节,寻求恰当的方法和措施,使桥梁的全寿命周期性能达到最优或优化。论文主要对全寿命周期理念在桥梁设计中的运用作了探讨和阐述。     

高速公路沥青路面全寿命经济分析

为了进一步提高公路建设的投资效益,在分析高速公路沥青路面耐久性和寿命周期关系的基础上,建立了沥青路面全寿命周期费用模型,该模型综合考虑了投资方案的初始修建费、未来的养护维修费、用户费用和寿命期内的其它相关费用。介绍了沥青路面全寿命经济分析的方法,讨论了全寿命经济分析过程中需要重点考虑的两个问题——沥青路面使用性能衰变的预测和维修时机、策略的选择,并对两种不同结构类型的沥青路面进行了实例分析。本文的研究可以为当前新形势下的公路建设项目投资决策和运营管理提供参考。     

大型公共建筑全寿命周期设计体系研究

剖析传统设计存在的弊端,坚持建筑性能与生态性能、经济性与艺术性相结合的原则,提出大型公共建筑全寿命周期设计理念,并与生态设计、可持续设计等方法进行对比分析;建立以可靠性与安全性设计、可施工性设计、工程系统寿命匹配性设计、全寿命周期费用优化设计、可维护性设计、可扩展性设计、防灾减灾设计、环境友好型设计和人性化设计九项目标为核心的大型公共建筑全寿命周期设计目标体系;构建大型公共建筑全寿命周期设计的集成分析路径由战略目标集成、工程系统集成、系统环境集成三个层次构成。为推动全寿命周期设计在大型公共建筑中的实施,制定了实施流程和EBS-OBS矩阵方法,并以某办公楼为例阐述了全寿命周期设计的实施步骤。     

城市长寿命沥青路面的设计与应用

针对城市沥青道路的早期破坏类型和其成因,提出按照长寿命沥青路面的设计理念和方法,同时使用高性能的沥青混合料,对城市沥青路面结构的设计和混合料的性能加以优化,从而大大延长城市道路路面的使用寿命,使其在40年之不发生结构性破坏,而只需对路面进行养护和简单的维修,这样既能提高路面的使用性能,又能够减少全寿命周期内的成本。     

地震易损性及全寿命费用评估方法研究

考虑地震激励随机性,以最大层间位移角为性能水平量化指标,采用基于概率密度演化理论的结构地震易损性分析方法,得到结构在不同强度地震作用下各级破坏状态的失效概率.提出结构损失期望与全寿命费用的计算方法,从而实现对结构全寿命周期的性能评估.最后,以钢筋混凝土框架结构住宅楼为例,将概率密度演化理论应用于结构全寿命费用的计算中,提高了损失期望与全寿命费用评估精度.     

Life-cycle of structural systems: recent achievements and future directions

Structural systems are under deterioration due to ageing, mechanical stressors, and harsh environment, among other threats. Corrosion and fatigue can cause gradual structural deterioration. Moreover, natural and man-made hazards may lead to a sudden drop in the structural performance. Inspection and maintenance actions are performed to monitor the structural safety and maintain the performance over certain thresholds. However, these actions must be effectively planned throughout the life-cycle of a system to ensure the optimum budget allocation and maximum possible service life without adverse effects on the structural system safety. Life-cycle engineering provides rational means to optimise life-cycle aspects, starting from the initial design and construction to dismantling and replacing the system at the end of its service life. This paper presents a brief overview of the recent research achievements in the field of life-cycle engineering for civil and marine structural systems and indicates future directions in this research field. Several aspects of life-cycle engineering are presented, including the performance prediction under uncertainty and optimisation of life-cycle cost and intervention activities, as well as the role of structural health monitoring and non-destructive testing techniques in supporting the life-cycle management decisions. Risk, resilience, sustainability, and their integration into the life-cycle management are also discussed.     

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.     

高性能钢结构建筑结构全寿命周期“三元一体化”指标体系研究

建立高性能钢结构建筑结构的全寿命周期结构性能、经济性和绿色可持续发展"三元一体化"指标体系,其中结构性能指标包括设计阶段的初始可靠度指标、时间指标、施工阶段指标、运营维护阶段指标及拆除阶段指标;经济性指标包括全寿命周期各阶段花费成本;绿色可持续指标包括资源利用、环境保护以及社会发展三方面。分析"三元"指标的"一体化"关系,提出各指标体系之间的联系与影响。以某商业综合体钢结构工程为例,验证所述指标体系在实际工程优化中的可行性与有效性。案例表明,该指标体系能够全面反应高性能钢结构建筑的高性能特征,对其全寿命周期分析与评估具有重要指导意义。在"三元一体化"视角下,提出高性能钢结构的设计建议。     

Risk-based life-cycle maintenance strategies for corroded reinforced concrete buildings located in the region with high seismic hazard

In this study, several developed models have been adopted to investigate deterioration induced by chloride ingress by considering uncertainty in order to estimate the initiation and rate of corrosion. Besides, the structural capacity and serviceability of RC buildings, i.e. the shear capacity, bending strength and width of cracking or spalling of columns and beams with corroded reinforcing bars, were also calculated using simple formulas developed from previous experiments. Based on the information of annual spalling/cracking and failure probabilities, the deterioration risk of an RC building attacked by chloride can be evaluated using the concept of reliability of a series system. In order to find the optimal maintenance plan, probabilistic effect assessment models for repair/retrofit strategies (five repair/retrofit strategies were selected) that consider the recurrence of deterioration in repaired areas and the deterioration proceeding in unrepaired areas were developed in this research. These models reflect the effects of the maintenance strategies on the failure and spalling probability directly and can be used to estimate the life-cycle performance and cost of RC buildings. Finally, on the basis of the minimal life-cycle cost, the optimal life-cycle maintenance strategy can also be identified by using the genetic algorithm; case studies were used to discuss the applicability of this system.     

Life-cycle cost optimal design of passive dissipative devices

The cost-effective performance of structures under natural hazards such as earthquakes and hurricanes has long been recognized to be an important topic in the design of civil engineering systems. A realistic comprehensive treatment of such a design requires proper integration of (i) methodologies for treating the uncertainties related to natural hazards and to the structural behavior over the entire life-cycle of the building, (ii) tools for evaluating the performance using socioeconomic criteria, as well as (iii) algorithms appropriate for stochastic analysis and optimization. A systematic probabilistic framework is presented here for detailed estimation and optimization of the life-cycle cost of engineering systems. This framework is a general one but the application of interest here is the design of passive dissipative devices for seismic risk mitigation. A comprehensive methodology is initially presented for earthquake loss estimation; this methodology uses the nonlinear time-history response of the structure under a given excitation to estimate the damage in a detailed, component level. A realistic probabilistic model is then presented for describing the ground motion time history for future earthquake excitations. In this setting, the life-cycle cost is uncertain and can be quantified by its expected value over the space of the uncertain parameters for the structural and excitation models. Because of the complexity of these models, calculation of this expected value is performed using stochastic simulation techniques. This approach, though, involves an unavoidable estimation error and significant computational cost, features which make efficient design optimization challenging. A highly efficient framework, consisting of two stages, is discussed for this stochastic optimization. An illustrative example is presented that shows the efficiency of the proposed methodology; it considers the seismic retrofitting of a four-story non-ductile reinforced-concrete building with viscous dampers.     

Stochastic life-cycle analysis: renewal-theory life-cycle analysis with state-dependent deterioration stochastic models

For the life-cycle analysis (LCA) of deteriorating engineering systems, it is critical to model and incorporate the various deterioration processes and associated uncertainties. This paper proposes a renewal-theory life-cycle analysis (RTLCA) with state-dependent stochastic models (SDSMs) that describe the deterioration processes. The SDSMs capture the multiple deterioration processes and their interactions through modelling the changes in the system state variables due to different deterioration processes. Then proper capacity and demand models that take the time-variant state variables as input are adopted to fully capture the impact of deterioration processes on the capacity, demand, and other time-variant performance indicators of the engineering system. The SDSMs are then integrated into RTLCA to efficiently evaluate various life-cycle performance quantities such as availability, operation cost and benefits of the engineering system. To implement the proposed formulation, a sampling-based approach is adopted to simulate samples from the relevant probability density functions (PDFs) to estimate the life-cycle performance quantities, while stochastic simulation-based approach is adopted to estimate the time-variant performance indicators needed to inform intervention activities. As an illustration, the proposed formulation is used to analyse the life-cycle performances of an example reinforced concrete bridge subject to deterioration due to corrosion and seismic loading.     

工程结构全寿命设计绿色指标体系构建

工程结构的绿色设计和绿色评价存在共性,在已建立的可持续发展工程结构全寿命周期设计理论体系基础上,参考国内外的绿色建筑评价体系,根据其共性构建了工程结构全寿命设计的绿色指标体系。该体系包含了三个指标,即以所处环境为对象的“环境评价指标”、以人为对象的“用户及社会满意度指标”和以区域和全球生态系统为对象的“可持续发展指标”。工程结构的全寿命设计传统指标是对现行设计方法的扩展和延伸,而绿色指标则是独立于传统设计方法体系之外的新体系,体现了全寿命设计方法的人文关怀和对自然的责任。为了将工程结构全寿命活动的环境和生态影响控制到最低水平,并使相关人群的利益最大化,通过指标分层、指标分类和权重分析,建立了建筑结构全寿命绿色设计指标体系。针对沿海高速公路桥梁结构的结构形式、用途和所处环境,构建了其全寿命设计绿色指标体系框架。     

混凝土结构耐久性设计原则、方法与标准

结合最新颁布的《混凝土结构耐久性设计标准》(GB/T 50476—2019)综述混凝土结构耐久性的总体设计原则、方法和规定。结合混凝土结构耐久性的定义,分析耐久性设计的三要素：性能劣化、耐久性极限状态以及设计使用年限,强调耐久性设计需要向全寿命耐久性规划拓展。结合标准规定,解析使用环境分类和等级划分表示性能劣化、耐久性极限状态以及设计使用年限针对整体结构与构件的不同含义。然后,结合定性设计方法分析典型环境下材料和构件层次上耐久性规定以及耐久性指标,针对防腐蚀附加措施和后张法预应力体系分析耐久性多重保护的理念。综述表明,标准最大程度总结了我国混凝土结构耐久性科学认识与工程实践,发展基于模型的性能化设计、设计阶段系统开展维护设计、推动耐久性多屏障设计理念是耐久性标准将来的发展方向。     

结构生命周期的可靠性管理

结构的抗力性能、使用条件、环境作用等都是随时间变化的过程。结构的运行规律复杂且具有大量的不确定性和不确知性,单纯依靠设计来保证结构的安全性是不够的,而应该综合考虑设计、检测、维护等策略对结构生命周期的可靠性进行管理。首先分析了目前的可靠度设计方法的优点和局限性,对可靠性管理的概念和必要性进行了阐述。继而引入时变可靠度和时点可靠度指标,建立一套考虑安全控制和风险优化的结构生命周期可靠性管理框架,并对其中的若干理论问题进行了讨论。该框架的特点在于,由静态思路转向动态思路,强调信息的更新和充分利用,与现有设计理论和工程实践保持协调。