Bi‐objective Modeling Approach for Repairing Multiple Feature Infrastructure Systems

A bi‐objective decision aid model for planning long‐term maintenance of infrastructure systems is presented, oriented to interventions on their constituent elements, with two upgrade levels possible for each element (partial/full repairs). The model aims at maximizing benefits and minimizing costs, and its novelty is taking into consideration, and combining, the system/element structure, volume discounts, and socioeconomic factors. The model is tested with field data from 229 sidewalks (systems) and compared to two simpler repair policies, of allowing only partial or full repairs. Results show that the efficiency gains are greater in the lower mid‐range budget region. The proposed modeling approach is an innovative tool to optimize cost/benefits for the various repair options and analyze the respective trade‐offs.     

Multiobjective Path Optimization for Critical Infrastructure Links with Consideration to Seismic Resilience

We study the generic problem of path optimization for a critical infrastructure link between two locations on the surface of the Earth in the vicinity of earthquake‐prone areas. The problem has two (conflicting) objective functions, one for minimizing the construction cost of the link and the other for minimizing the number of potential repairs along the link in the wake of earthquakes. In our model, the Earth's surface is approximated by a triangulated manifold, and ground motion intensity data are used to provide a measure of repair rate. We approach the multiobjective variational problem by first converting it into a single objective variational problem using the weighted sum method. Then, we show that the problem can be further transformed into an Eikonal equation and solved by a computationally efficient algorithm based on the fast marching method. Extensive simulations are performed on real‐world three‐dimensional geographical data, from which we obtain Pareto optimal solutions that provide insight and guidance to design trade‐offs between cost effectiveness and seismic resilience.     

应对海平面上升问题的城市土地利用格局 脆弱性多情景模拟评估及应对策略

全球气候变化引发的海平面上升对沿海区域的环境和社会经济发展造成巨大破坏。以珠三角广州南沙为研究区域,基于传统、自然增长和规划控制3种土地利用格局预设发展情景,采用PLUS(Patch-generating Land Use Simulation Model)模型模拟各情景下的未来土地利用格局。同时,针对近期(2030年)、中期(2050年)和远期(2100年)3种不同海平面上升叠加风暴潮风险下的土地利用格局脆弱性开展多情景定量化评估,并提出应对策略。结果显示：1)3种土地利用格局发展情景中,传统格局情景能够最有效地应对或缓解海平面上升和风暴潮灾害风险,而自然增长情景应对未来海岸灾害的能力最弱;2)从不同土地利用类型的脆弱性程度来看,城镇建设用地的综合脆弱性最高,而村庄建设用地的综合脆弱性最低;3)根据不同发展情景及灾害风险应采用综合防御、适应及撤退等多种应对策略。综合考虑了未来土地利用格局的多种变化情景、灾害风险及应对策略,能够为滨海城市应对未来海岸灾害的适应性规划提供决策参考。     

Adaptation Planning and Hazard Mitigation for Interdependent Infrastructure Systems to Enhance Urban Resilience Under Climate Change

Climate change and natural hazards have created multiple impacts on human settlements. Urban planning and design are effective tools in dealing with climate adaptation and mitigation issues. However, climate risk and its impacts are multiscale and complex due to interdependence between urban infrastructure systems. Identifying adaptation strategies to cope with these impacts requires planners to understand potential interdependent and interrelated consequences of infrastructure failure under natural hazards, and evaluate cascading and cumulative effects of climate change. This article discussed opportunities and challenges to incorporate interdependent social and physical infrastructure systems in the adaptation planning and hazard mitigation process, including climate hazard assessment, adaptation goal identification, adaptation strategy development, and implementation. The availability of urban big data and high computational resources will enable urban planners and decision-makers to better deal with those complex impacts from climate change and natural hazards. Successful adaptation planning and hazard mitigation for interdependent infrastructure systems also needs to solve issues in uncertainties of climate projection, institutional barriers of adaptation, and challenges of urban big data. Potential solutions to these challenges would include cooperation among multi-disciplinary experts, coordination between different levels of governments, and developing the ethical framework for data protection and robust methodologies to detect and reduce data bias.     

Network‐Level Road Pavement Maintenance and Rehabilitation Scheduling for Optimal Performance Improvement and Budget Utilization

Abstract: This article discusses how to efficiently and completely solve a bi‐objective pavement maintenance and rehabilitation‐scheduling problem, which aims at optimizing two objectives of pavement condition improvement and budget utilization in a simultaneous manner. This problem may be addressed by the weighting method, constraint method, ranking method, and various metaheuristic methods. However, none of these methods can guarantee the complete Pareto‐optimal solution set, which would potentially lead to suboptimal decisions. In this article, a parametric method is suggested to solve the bi‐objective pavement maintenance and rehabilitation‐scheduling problem. The effectiveness and efficiency of the parametric method is investigated and demonstrated through a case study using the real‐world data set from the Dallas District's Pavement Management Information System. A performance comparison between the widely used weighting method and the parametric method clearly justifies the computational advantages of the parametric method.     

城市道路安全基础设施评价方法研究

根据对城市道路安全基础设施的需求分析,探讨城市道路安全基础设施设置的评价原则及要求,按对城市道路安全基础设施的定义和功能,构建了城市道路安全基础设施的评价指标体系。应用模糊综合评价法建立城市道路安全基础设施评价方法,并对上海闵行区城市道路安全基础设施现状进行了评价方法检验。     

提升道路养护机械专业化水平的途径探索

分析了交通新形势下的道路养护机械专业化的发展现状和主要问题,探讨了提升道路养护机械专业化水平的途径。道路养护机械的个性化定制可以有效解决现有专业道路养护机械种类少、性能低、适应性不强等问题,构建合理的道路养护机械管理体系有利于全面掌控养护机械的作业状态,实行全寿命周期管理,促使其发挥最优的经济效益。     

韧性城市视角下海平面上升对沿海城市的影响及对策研究——以厦门市为例

随着全球气候不断变化,海平面上升速率逐渐加快,严重影响着沿海城市的安全与可持续发展,提升沿海城市韧性已经成为其应对气候变化的战略共识。基于韧性城市理论,构建了海平面上升影响分析及韧性评价模式,并以厦门市为例,展开了不同时间情景下的影响分析及韧性评估。结果表明,2030年和2050年在海平面上升的影响下,受灾人口将增加6万人和8万人,受灾建设用地将增加5.1km^2和8.3km^2,受灾道路将增加14.6km和24.0km。同时通过空间评估,明确了不同地区韧性提升的重点。最后针对性地提出了厦门城市韧性提升的策略。     

3D Parametric Modeling of Complex Geological Structures for Geotechnical Engineering of Dam Foundation Based on T‐Splines

We propose a novel geological modeling method based on T‐splines for computer‐aided design (CAD) and building information modeling (BIM) systems of geotechnical engineering and perform original research on special T‐splines modeling strategies and the algorithm aiming at depicting structural complexity to develop and introduce the T‐splines technology into engineering geological modeling. A methodology of parametric geological modeling with T‐splines is established, where a topology‐geometry modeling strategy is adopted, the inhomogeneity, arbitrary connectivity and discontinuity of geological structures are quantified and associated with T‐spline surface elements in the topology phase. A representative parametric algorithm called IBALR is presented in the context of dam foundation geological modeling to generate an inhomogeneous local refined T‐mesh with high genus topology which can fit a complex geological layer. The proposed method is flexible and effective in improving geological representation within geotechnical engineering.     

A Cell‐Based Distributed‐Coordinated Approach for Network‐Level Signal Timing Optimization

This article develops an efficient methodology to optimize the timing of signalized intersections in urban street networks. Our approach distributes a network‐level mixed‐integer linear program (MILP) to intersection level. This distribution significantly reduces the complexity of the MILP and makes it real‐time and scalable. We create coordination between MILPs to reduce the probability of finding locally optimal solutions. The formulation accounts for oversaturated conditions by using an appropriate objective function and explicit constraints on queue length. We develop a rolling‐horizon solution algorithm and apply it to several case‐study networks under various demand patterns. The objective function of the optimization program is to maximize intersection throughput. The comparison of the obtained solutions to an optimal solution found by a central optimization approach (whenever possible) shows a maximum of 1% gap on a number of performance measures over different conditions.     

复杂山地大气环境三维建模与仿真方法

本文主要探讨复杂山地大气环境三维建模与数值仿真方法,介绍了三维数值地形图的概念及其表示方法,建立了相应的数据文件格式。针对某铀矿井尾气扩散实际问题创建了相应仿真模型,进行了仿真计算,并把仿真结果与实验结果进行了对比。从网格划分和仿真计算结果来看,证明这种方法简单且实用。     

Modeling of two‐cell cores for three‐dimensional analysis of multi‐story buildings

The reliability of simplified models for single‐cell cores, and particularly for open and semi‐open U‐cross‐section cores, has been the subject of many research papers in the recent past. In contrast, on an international level, only little mention has been made of the efficiency of such models for multi‐cell cores of multi‐story R/C buildings. This paper evaluates and comments on the reliability of several simplified models for open two‐cell cores that are often used in practice. The models examined are: (a) models composed of equivalent columns in alternative configurations; (b) models composed of panel elements; and (c) finite shell element models with one element for each flange in each story. These models are compared with one another and with the solution considered accurate, which is the one obtained by using a finite element method consisting of an adequately dense mesh of finite shell elements. The conclusions obtained refer to both the simplified modal response analysis and the multi‐modal response spectrum analysis, while the specific assumptions for the numerical investigations are compatible with the provisions of modern seismic design codes. Copyright © 2000 John Wiley & Sons, Ltd.     

高层住宅自然通风数值模拟

基于计算流体动力学CFD软件,选用Realizablek-ε湍流模型,对某高层住宅周围的流场进行了数值模拟,通过分析建筑物表面的压力分布,计算得到各户型在不同工况下的风压差系数及自然通风换气次数,分析了个别户型通风效果较差的原因.结果表明:在通风效果较差户型入户门上方开设通风孔,可以有效地改善室内自然通风效果,并给出了合理的通风孔面积.     

A Modified Sliding Mode Fault Tolerant Control for Large‐Scale Civil Infrastructure

Adaptable active control strategies besides advance sensors and actuators technologies lead to higher performance of vibrational control in civil infrastructures under severe ground motions. These resilience control systems are robust against model uncertainties as well as being online recoverable from the malfunctioning of sensors and actuators. In this study, resilient control system based on sliding mode (SM) fault detection observer and SM fault tolerant control is improved for actuator fault in large‐scale systems. The SM fault detection observer is modified for eliminating the excessive chattering in estimating states and actuators’ fault, and the reconfigurable SM fault tolerant control is improved to minimizing input forces in control framework under seismic action. Design of observer and controller is performed using linear matrix inequalities. Numerical simulations on the cable‐stayed bridge benchmark demonstrate the effectiveness of the proposed fault‐tolerant system. Despite the high order of this large‐scale structure, the proposed fault detection and diagnosis method can effectively find the location and size of faults in actuators without performance degradation and computational costs. The fault‐tolerant controller maintains the performance of the structure at an acceptable level in the post‐fault case by redistribution of control signal to actuators.     

两岔口隧道新奥法施工过程模拟原理及Ⅲ级围岩施工方法

通过湖南两岔口公路隧道施工实例,介绍了新奥法原理及Ⅲ级围岩根据新奥法原理采用的具体施工方法,同时介绍了两岔口隧道施工过程模拟的原理.     

Predicting Cost Escalation Pathways and Deviation Severities of Infrastructure Projects Using Risk‐Based Econometric Models and Monte Carlo Simulation

In the past decade, infrastructure‐related legislation in the United States has consistently emphasized the need to measure the variation associated with infrastructure project cost estimates. Such cost variability is best viewed from the perspective of the project development phases and how the project cost estimate changes as it evolves across these phases. The article first identifies a few gaps in the cost overrun literature. Then it introduces a methodology that uses risk‐based multinomial models and Monte Carlo simulation involving random draws to predict the probability that a project will follow a particular cost escalation pathway across its development phases and that it will incur a given level of cost deviation severity. The article then uses historical data to demonstrate how infrastructure agencies could apply the proposed methodology. Statistical models are developed to estimate the probability that a highway project will follow any specific cost escalation pathway and ultimately, a given direction and severity of cost deviation. The case study results provided some interesting insights. For a given highway functional class, larger project sizes are associated with lower probability of underestimating the final cost; however, such a trend is not exhibited by very large projects (total cost exceeding $30M). For a given project size, higher class roads were generally observed to have a lower probability of underestimating the final cost, compared to lower class roads and this gap in probability narrows as the project size increases. It was determined that a project's most likely pathway of cost escalation is not a guarantee that it will yield any particular direction of cost deviation. The case study results also confirmed the findings of a few past studies that the probabilities of cost escalation pathways and the cost overruns differ significantly across highway districts, and attributed this to differences in administrative culture and work practices across the districts. Infrastructure managers can use the developed methodology to identify which projects are likely to experience a particular pathway of cost escalation, the direction and severity of cost deviation, and to develop more realistic project contingency estimates.     

提高机械化施工水平,促进公路建设事业的发展

1提高施工机械化水平，促进工程建设随着我国加大基础设施的建设力度，机械化施工已逐步取代了人海战术。施工机械化程度的高低,对工程建设的投资控制、进度控制和质量控制起着十分重要的作用。１．１提高了施工组织管理水平从传统的施工方法转变为机械化施工，必然会引起生产组织形式和管理形式的变革。在施工中，根据工程量及施工现场条件，对整个施工工序所需配备的机械及重点部位的机械配套进行综合平衡，可以合理配置各道工序的所需机械，使机械设备的作用得到较好的发挥。１．２加快了施工进度工程施工中的时间安排基本上采取平行顺序…     

Modal Identification for High‐Rise Building Structures Using Orthogonality of Filtered Response Vectors

The modal parameters of civil structures (natural frequency, mode shape, and mode damping ratio) are used for structural health monitoring (SHM), damage detection, and updating the finite element model. Long‐term measurement has been necessary to conduct operational modal analysis (OMA) under various loading conditions, requiring hundreds of thousands of discrete data points for estimating the modal parameters. This article proposes an efficient output‐only OMA technique in the form of filtered response vector (frv)‐based modal identification, which does not need complex signal processing and matrix operations such as singular value decomposition (SVD) and lower upper (LU) factorization, thus overcoming the main drawback of the existing OMA technique. The developed OMA technique also simplifies parameters such as window or averaging, which should be designed for signal processing by the OMA operator, under well‐separated frequencies and loading conditions excited by white noise. Using a simulation model and a 4‐story steel frame specimen, the accuracy and applicability were verified by comparing the dynamic properties obtained by the proposed technique and traditional frequency‐domain decomposition (FDD). In addition, the applicability and efficiency of the method were verified by applying the developed OMA to measured data, obtained through a field test on a 55‐story, 214‐m‐tall high‐rise building.     

Late Modernity to Postmodern? The Rise of Global Resilience and its Progressive Potentials for Local Disaster Planning (Seattle and Paris)

ABSTRACT

This paper studies how approaches to disaster planning have been changing with the rise of ‘resilience,’ a concept that has been widely recommended by various international institutions. The critical studies on resilience argue that resilience only serves to legitimise a neoliberal policy agenda that is compatible with a global economic system of capitalism. Contesting that position, this paper argues that the rise of resilience can imply a shift in the mode of governance, and an opportunity for planners to engage with more progressive practices. To make this argument, we propose a ‘postmodern lens’ through which resilience can be seen as an attitude and a style of governance that goes beyond neoliberal assumptions by embracing uncertainty and complexity of governance challenges. Postmodern framing of resilience notes (1) how the concept can initiate a shift in the planner’s view of and practices on knowledges (going beyond ‘expert knowledge’), (2) how the flexibility of the concept can be used for developing political narratives that are progressive (3) how the concept can open up potential venues for nonconventional powers to intervene in policy making processes. To demonstrate how this lens works, we compare the cases of Seattle and Paris, which have drastically different risk governance political structures.