Paolo Bocchini

Resilience and Sustainability of Civil Infrastructure: Toward a Unified Approach

In recent years, the concepts of resilience and sustainability have become very topical and popular. The concept of sustainability rose to prominence in the late 1980s and became a central issue in world politics, when the construction industry began to generate the first sustainable building assessment systems with more or less equally weighted environmental, economic, and social aspects for office buildings over their life cycles. On the other hand, resilience is usually connected to the occurrence of extreme events during the life cycle of structures and infrastructures. In the last decade, it has been used to minimize specifically direct and indirect losses from hazards through enhanced resistance and robustness to extreme events, as well as more effective recovery strategies. A detailed comparison of the studies dealing with either infrastructure sustainability or resilience presented in this paper leads to the conclusion that they have a vast number of similarities and common characteristics. For instance, they both combine structural analyses with social and economic aspects; they both rely on techniques for the life-cycle analysis and decision making; they both are in an early stage, where the academic world is trying to find the best way to promote the application of the scientific results among professional engineers and the industry. Indeed, both approaches try to optimize a system, such as a civil infrastructure system, with respect to structural design, utilized material, maintenance plans, management strategies, and impacts on the society. However, for the most part, researchers and practitioners focusing on either resilience or sustainability operate without a mutual consideration of the findings, which leads to a severe inefficiency. Therefore, this paper suggests that resilience and sustainability are complementary and should be used in an integrated perspective. In particular, the proposed approach is rooted in the well-established framework of risk assessment. The impact of the infrastructure and its service states on the society in normal operational conditions (assessed by sustainability analysis) and after exceptional events (assessed by resilience analysis) should be weighted by the associated probabilities of occurrence and combined in a global impact assessment. The proposed perspective and assessment technique is applicable to various types of civil infrastructure systems, but the case of transportation networks and bridge systems is emphasized herein. A numerical application dealing with the comparative analysis of two possible bridge layouts is presented to exemplify the approach. The results show that both resilience and sustainability analyses assess a relevant amount of the impact of the bridge on the community where it is built, so neither one can be neglected.

Optimal Resilience- and Cost-Based Postdisaster Intervention Prioritization for Bridges along a Highway Segment

In this paper, a general framework for the optimal resilience- and cost-based prioritization of interventions on bridges distributed along a highway connection between two cities that have experienced a disruptive natural or man-made event is proposed. Given the structural damage levels after the extreme event and the bridge characteristics, the proposed computational procedure finds the best intervention schedules, defined as starting time and progress pace of the restoration. The possible intervention schedules are considered optimal when they maximize the resilience of the highway segment and minimize the total cost of interventions. Because the two objectives are conflicting, the procedure uses genetic algorithms (GAs) to automatically generate a Pareto front of optimal solutions. Numerical examples are presented and discussed.

Restoration of Bridge Networks after an Earthquake: Multicriteria Intervention Optimization

This paper presents an optimization procedure for the restoration activities associated with the bridges of a transportation network severely damaged by an earthquake. The design variables are (i) the time intervals between the occurrence of the distress and the start of the interventions on each bridge of the network; and (ii) the restoration pace of the interventions, which represents a measure of the funding allocated to each bridge. The objectives of the optimization are the maximization of the network resilience, the minimization of the time required to reach a target functionality level, and the minimization of the total cost of the restoration activities. Because the first two objectives clearly conflict with the last one, the optimization procedure does not provide a unique solution, but an entire set of Pareto solutions. A numerical example involving a complex, existing transportation network in Santa Barbara, California, illustrates the capabilities of the proposed methodology.

A probabilistic computational framework for bridge network optimal maintenance scheduling

This paper presents a probabilistic computational framework for the Pareto optimization of the preventive maintenance applications to bridges of a highway transportation network. The bridge characteristics are represented by their uncertain reliability index profiles. The in/out of service states of the bridges are simulated taking into account their correlation structure. Multi-objective Genetic Algorithms have been chosen as numerical tool for the solution of the optimization problem. The design variables of the optimization are the preventive maintenance schedules of all the bridges of the network. The two conflicting objectives are the minimization of the total present maintenance cost and the maximization of the network performance indicator. The final result is the Pareto front of optimal solutions among which the managers should chose, depending on engineering and economical factors. A numerical example illustrates the application of the proposed approach.

Graphical User Interface for Guided Acoustic Waves

This paper presents GUIGUW v0.1, a graphical user interface (GUI) for the computation of stress-guided wave dispersive features. The software exploits semianalytical finite-element (SAFE) formulations for the calculation of wave-propagation characteristics. The interface allows for the selection of geometrical, mechanical, and frequency-related parameters for the computation. Isotropic and anisotropic materials with linear elastic and linear viscoelastic rheological behaviors can be considered, and any waveguide cross section can be modeled. For each existing wave, the dispersive results can be represented in terms of wave number, wavelength, phase velocity, group velocity (for undamped waveguides), energy velocity, and attenuation (for damped waveguides). By simply working with the GUI, original results for guided stress waves can be obtained.

Bridge network performance, maintenance and optimisation under uncertainty: accomplishments and challenges

This article presents a critical review of the state-of-the-art in the field of bridge network performance analysis, reliability assessment, maintenance management and optimisation. Previous accomplishments and results are summarised while stressing the aspects of the analysis of a transportation network, which are more challenging for a structural engineer. For instance, the bridge network is described as a spatially distributed system at a scale that is much larger than any individual structure. This requires a different perspective in the modelling of natural extreme events and involves models for the interaction between the individual components (i.e. bridges) and the overall network. Then, the time domain is investigated, and the problem of structural deterioration and its effects on the network performance are addressed. The most important differences between a transportation network and other lifelines are considered next, and techniques for the transportation network analysis and performance assessment are summarised. Finally, a set of selected problems and applications is considered and additional challenges are identified and suggested for future developments.

Resilience as Optimization Criterion for the Rehabilitation of Bridges Belonging to a Transportation Network Subject to Earthquake

This paper deals with the concept of “resilience” and proposes its use as optimization criterion for the rehabilitation of a transportation network subject to earthquake. The most earthquake damage prone components of a transportation network are certainly its bridges; therefore, the proposed approach focuses on bridge rehabilitation interventions. The design variables of the optimization problem are the application times and durations of the interventions on bridges of the network. These durations are determined by the amount of funding invested on each bridge. Hence, the proposed methodology provides the optimal rehabilitation schedule and cost breakdown for all the bridges of the network. A numerical application is presented to illustrate the proposed approach and to show its capabilities.

Connectivity-Based Optimal Scheduling for Maintenance of Bridge Networks

This paper addresses the issue of connectivity- and cost-based optimal scheduling for maintenance of bridges at the transportation network level. Previous studies in the same field have considered the connectivity just between two points or other network performance indicators, such as the total travel time. In this paper, the maximization of the total network connectivity is chosen as the objective of the optimization, together with the minimization of the total maintenance cost. From a computational point of view, several numerical tools are combined to achieve efficiency and applicability to real cases. Random field theory and numerical models for the time-dependent structural reliability are used to handle the uncertainties involved in the problem. Latin hypercube sampling is used to keep the computational effort feasible for practical applications. Genetic algorithms are used to solve the optimization problem. Numerical applications to bridge networks illustrate the characteristics of the procedure and its applicability to realistic scenarios.

Performance Indicators for Structural Systems and Infrastructure Networks

AbstractEstablishing consistent criteria for assessing the performance of structural systems and infrastructure networks is a critical component of communities’ efforts to optimize investment decisions for the upkeep and renewal of the built environment. Although member-level performance and reliability assessment procedures are currently well-established, it is widely recognized that a member-oriented approach does not necessarily lead to an efficient utilization of limited resources when making decisions related to the management of existing deteriorating structures or lifeline systems, especially those that may be exposed to extreme events. For this reason, researchers have renewed their interests in developing system-level assessment methods as a basis to modern structural and infrastructure performance evaluation and design processes. Specifically, system-level performance metrics and characteristics such as reliability, redundancy, robustness, resilience, and risk continue to be refined. The objecti...

Non-destructive parametric system identification and damage detection in truss structures by static tests

This article presents theoretical background, computational implementation and numerical applications of a study devoted to the non-destructive parametric identification of truss structures by means of static load tests. The proposed methodology determines the (residual) stiffness of the bars. Therefore, it detects the elements with global or localised damages and assesses the extent of damage in terms of stiffness loss. A novelty introduced by the proposed technique is the ability to take into account plane and three-dimensional structures, both statically determinate and indeterminate. Moreover, when only a partial set of measurements is available, the procedure uses genetic algorithms to overcome the lack of information. Five numerical applications are collected to prove the capabilities of the proposed methodology and to exemplify the procedure.