Exploring the properties of cost overrun risk propagation network (CORPN) for promoting cost management

Construction cost overrun chronically plagues contractors. To address the issue, numerous studies have explored cost overrun risks (CORs). Nevertheless, their methods of identifying risk relationship are susceptible to experts’ experience. In addition, they fail to unearth the relationship structure information and analyze the risk propagation effect. To fill these gaps, this paper intends to propose a methodology that integrates the engineering case analysis and complex network theory, so as to obtain a stable relationship structure and reveal its inherent property. First, 52 CORs and 158 risk paths are extracted from 156 engineering cases, followed by the establishment of a cost overrun risk propagation network (CORPN). Finally, the statistical properties of CORPN are explored. The results indicate that CORPN presents the topological property of heterogeneity. A large number of risk paths can be blocked through preventing the CORs with large total degree, like delay in construction period and engineering quantity increase. Meanwhile, CORPN shows the small-world property. The efficiency of risk propagation can be reduced through preventing the CORs with high betweenness centrality, such as lack of technical skill and experience. These findings contribute to the formulation of beforehand strategies that promote the cost management

Optimal rehabilitation planning for aged water distribution mains considering cascading failures of interdependent infrastructure systems

This is the final version. Available on open access from IWA Publishing via the DOI in this recordData availability statement: All relevant data are included in the paper or its Supplementary Information.Water distribution networks (WDNs) with other infrastructures constitute a complex and interdependent multi-utility system. Considering interdependencies between WDNs and other urban infrastructures, this work proposes WDN intervention planning using a dynamic multi-utility approach to tackle the challenges of pressure deficits and cascading failures by the decoupling of different infrastructure systems. For this purpose, the study develops reliability indices representing the hydraulic and decoupled statuses of WDNs with neighbor infrastructures; the hydraulic reliability represents the robustness of the network against the water pressure deficit, and decoupling reliability represents the extent to which WDN elements are decoupled from other assets elements. A multi-objective optimization algorithm is employed to develop rehabilitation strategies by introducing three approaches for WDN upgrade following a phased design and construction method. Evaluating intervention plans based on construction cost, reliability and cascade effects shows that, under budget limitation conditions, decoupling a WDN could significantly save the cascade cost such that 1% improvement in the decoupling reliability brings about 157.42 billion Rials cascade cost saving to asset managers. On the other hand, the decoupled network is weak against hydraulic reliability, which could make it by far less resilient network than the coupled network with around 75% hydraulic reliability difference.University of InnsbruckAustrian Academy of Sciences (ÖAW)Austrian Organization Funding for Basic ResearchDOC FellowshipAustrian Science Fund (FWF)European Union Horizon 202

Graph Theoretic Approaches to Understand Resilience of Complex Systems

Modern society is critically dependent on a network of complex systems for almost every social and economic function. While increasing complexity in large-scale engineered systems offer many advantages including high efficiency, performance and robustness, it inadvertently makes them vulnerable to unanticipated perturbations. A disruption affecting even one component may result in large cascading impacts on the entire system due to high interconnectedness. Large direct and indirect impacts across national and international boundaries of natural disasters like Hurricane Katrina, infrastructure failures like the Northeast blackout, epidemics like the H1N1 influenza, terrorist attacks like the 9/11, and social unrests like the Arab Spring are indicative of the vulnerability associated with growing complexity. There is an urgent need for a quantitative framework to understand resilience of complex systems with different system architectures. In this work, a novel framework is developed that integrates graph theory with statistical and modeling techniques for understanding interconnectedness, interdependencies, and resilience of distinct large-scale systems while remaining cognizant of domain specific details. The framework is applied to three diverse complex systems, 1) Critical Infrastructure Sectors (CIS) of the U.S economy, 2) the Kalundborg Industrial Symbiosis (KIS), Denmark and 3) the London metro-rail infrastructure. These three systems are strategically chosen as they represent complex systems of distinct sizes and span different spatial scales. The framework is utilized for understanding the influence of both network structure level properties and local node and edge level properties on resilience of diverse complex systems. At the national scale, application of this framework on the U.S. economic network reveals that excessive interconnectedness and interdependencies among CIS significantly amplify impacts of targeted disruptions, and negatively influence its resilience. At the regional scale, analysis of KIS reveals that increasing diversity, redundancy, and multi-functionality is imperative for developing resilient and sustainable IS systems. At the urban scale, application of this framework on the London Metro system identifies stations and rail connections that are sources of functional and structural vulnerability, and must be secured for improving resilience. This framework provides a holistic perspective to understand and propose data-driven recommendations to strengthen resilience of large-scale complex engineered systems

相互依存性を有するクリティカルインフラストラクチャーの地震時性能と地震災害マネジメントに関する研究

京都大学0048新制・課程博士博士(工学)甲第17142号工博第3632号新制||工||1551(附属図書館)29881京都大学大学院工学研究科都市社会工学専攻(主査）教授 清野 純史, 教授 小池 武, 准教授 古川 愛子学位規則第4条第1項該当Doctor of Philosophy (Engineering)Kyoto UniversityDFA