Resilient Cities and Structures最新文献

This study develops a comprehensive framework to assess the resilience of transportation networks consisting of deteriorating bridges subjected to earthquake events. For this purpose, the structural capacity of highway bridges is estimated during their service life using a set of detailed finite-element models that simulate the progress of deterioration. The developed models take into consideration the main environmental stressors and determine the extent of capacity loss as a function of time. Based on the degraded state of structural components, seismic fragility analyses are performed to obtain a probabilistic evaluation of the extent of damageability of the existing bridges under seismic events. Since each transportation link normally consists of a number of bridges, the state of damage in the individual bridges is mapped to the corresponding links and a scenario-based approach is employed to estimate the resilience of the entire transportation network. To demonstrate how the consequences of structural degradation can be integrated into the developed framework, the large-scale transportation network of Los Angeles and Orange counties is investigated under a series of aging and earthquake scenarios. The outcome of this study indicates how the estimates associated with the functionality measures of a transportation network can be improved if the age factor is properly integrated into the framework used for resilience assessment.

Risk assessment and mitigation programs have been carried out over the last decades in the attempt to reduce transportation infrastructure downtime and post-disaster recovery costs. Recently, the concept of resilience gained increasing importance in design, assessment, maintenance, and rehabilitation structures and infrastructure systems, particularly bridges and transportation networks, exposed to natural and man-made hazards. In the field of disaster mitigation, frameworks have been proposed to provide a basis for development of qualitative and quantitative models quantifying the functionality and resilience at various scales, including components, groups and systems within infrastructure networks and communities. In these frameworks, the effects of aging and environmental aggressiveness must be explicitly considered, affecting the structural performance and functionality of civil infrastructure systems. Significant efforts have been made to incorporate risk and resilience assessment frameworks into informed decision making to decide how to best use resources to minimize the impact of hazards on civil infrastructure systems. This review paper is part of these efforts. It presents an overview of the main principles and concepts, methods and strategies, advances and accomplishments in the field of life-cycle reliability, risk and resilience of structures and infrastructure systems, with emphasis on seismic resilience of bridges and road networks.

After a brief overview of how the dimensionless resilience index has been calculated in the past for buildings, and some of the shortcomings of that approach, the use of a resilience deficit index is advocated to overcome some of these shortcomings. An example is provided and the pros and cons of each approach are discussed, with broad recommendations applicable to the quantification of building resilience.

Internet data center buildings have great importance for maintaining the post-earthquake functionality of telecommunication networks. It is essential to maintain the functionality of internet data center buildings during earthquakes or recover immediately after earthquakes, which is referred to as seismic resilience. In this study, a seismic resilience assessment framework based on the Chinese code GB/T 38591-2020 is introduced first. The seismic damage and post-earthquake repair of both structural components and non-structural components are considered in the resilience assessment framework. A method for post-earthquake functionality loss quantification is proposed based on damage state and functionality loss of component. The subsystem level and system level functionality loss can be obtained by an integration principle. The seismic resilience of a typical internet data center building was evaluated to demonstrate the effectiveness of the proposed method. To enhance the seismic resilience level, different disaster mitigation techniques including the energy dissipation technology using buckling restrained braces and the base-isolation technology using lead-rubber bearings are adopted. The seismic resilience is quantified and the corresponding seismic resilience curves under different earthquake intensities are developed based on evaluation results.

This paper develops a practice-oriented seismic design procedure for an emerging lateral force resisting system. The system combines the favorable re-centering feature with the attractive hybrid damping capacity. The system overcomes the detrimental frame expansion effect that occurs in conventional self-centering building frames without the cost of building space. Following the proposed design procedure, multiple designs with different parameters to achieve performance objectives were performed for a representative three-story building in which the considered lateral force resisting system is used to resist the seismic forces. Nonlinear response history analyses were performed for the designs to evaluate the applicability and adequacy of the proposed design approach. Based on the analyses conducted in this research, it was found that the considered system designed using the proposed approach can meet both transient and residual inter-story drift requirements specified for the selected performance objectives. While an initial design per the proposed design approach may be inadequate, the re-design strategy recommended can help transform the design to an acceptable one after only one round of modification. Moreover, the composition of hybrid damping may affect the maximum floor acceleration responses. In this study, the maximum floor acceleration can be reduced 12.75% at most by replacing hysteretic damping with viscous damping. This should be included in design consideration in the proposed approach through adjusting the hybrid damping composition.

The spatial distribution of the world population is uneven, with a density of about $40\%$ living in coastal regions. The trend is expected to continue in both demographic indicators and urban development rate, being many coastal cities in seismic- and tsunami-prone regions and built through informal and unplanned settlements, exposing their population and assets to such hazards. Recent tectonic-triggered events raised awareness of the cascading earthquake and tsunami threat and highlighted the paucity of structural design criteria considering the cumulative effects of both. By being exposed to the ground-motion, the structures’ resistance may decrease and become residual/non-existent to support the incoming tsunami, implying an underestimation of the risk.

Risk management can benefit from reinforcing the ties between natural hazards and engineering practitioners, linking science and industry, and promoting dialogue between risk analysts and policy-makers. Motivated by the expansion plans of an internationally-sized deep-water port located in a tsunami-prone region, a reflection on the work needed to perform a multi-risk assessment and the challenges yet to overcome is introduced to emphasize the challenge of combining safety requirements with financial and ecologic concerns. A conceptual interdisciplinary-based methodology is proposed to support uncertainty-aware, systematic and informed decisions.

Underground infrastructure (UI) plays a great important role in the urbanization and modernization of megacities in the world. However, the intensive development of the UI during the past decades has posed great risks to the safety of city infrastructures under the impact of multi-hazards, especially with the condition of global climate change. In this paper, a general conceptualized framework to assess the resilience of UI in cities under multi-hazards impact is proposed. The urban tunnel system, e.g., metro tunnel, road tunnel etc., is selected as the typical underground infrastructure discussed with the emphasis both on the structural level in terms of mechanical behaviors and system level in terms of network efficiency. The hazards discussed in this paper include the natural hazards and human-related ones, with emphasis on earthquake, flood, and aggressive disturbances caused by human activities. After the general framework proposed for resilience of the structural and network behavior of the UI, two application examples are illustrated. The structural resilience of the shield tunnel under earthquake impact is analyzed by using the proposed resilience model, and the network resilience of the road tunnel system under the flood impact due to climate change is analyzed, respectively. The resilience enhancement by using the adaptive design strategy of real-time observational method is mathematically presented in this case. Some other practical engineering recovery measures are briefly discussed at the end of this application example. The findings in the application examples should be helpful to enhance the resilience-based design of the structural and network of tunnels from the component to the system level.