Duygu Saydam

Maintenance, management, life-cycle design and performance of structures and infrastructures: a brief review

The optimal decisions to maintain or improve the reliability and functionality of structures and infrastructure systems can only be achieved through proper integrated management planning in a life-cycle comprehensive framework. Structure and Infrastructure Engineering (SIE) is an international journal dedicated to recent advances inmaintenance, management, and life-cycle performance of a wide range of infrastructures. The purpose of this article is to provide a brief review of the recent research accomplishments in the field of design, maintenance, life-cycle management, and optimisation of structures and infrastructures reported in papers published in SIE during the period 2005–2011. The papers are categorised under main topics and very briefly discussed.

Reliability analysis and damage detection in high-speed naval craft based on structural health monitoring data

Current and future trends in naval craft design are leaning toward the development of high-speed and high-performance vessels. Lack of information on wave-induced loads for these vessels presents a challenge in ensuring their safety that is best tackled with monitoring operational loads and detecting damage via structural health monitoring (SHM) systems. These monitoring systems, however, require efficient statistical and probabilistic procedures that are able to effectively treat the uncertainties inherent in the massive volumes of collected data and provide interpretable information regarding the reliability and condition of the craft structure. In this article, an approach for using SHM data in the reliability analysis and damage detection in high-speed naval craft (HSNC) under uncertainty is presented. This statistical damage detection technique makes use of vector autoregressive modeling for detection and localization of damage in the ship structure. The methodology is illustrated on an HSNC, HSV-2. Data obtained from seakeeping trials of HSV-2 were treated as the SHM data mentioned above.

Sustainability of Highway Bridge Networks under Seismic Hazard

In order to evaluate the seismic risk of transportation networks, it is necessary to develop a methodology that integrates the probabilities of occurrence of seismic events in a region, the vulnerability of the civil infrastructure, and the consequences of the seismic hazard to the society, environment, and economy. In this article, a framework for the time-variant seismic sustainability and risk assessment of highway bridge networks is presented. The sustainability of the network is quantified in terms of its social, environmental, and economic metrics. These include the expected downtime, expected energy waste and carbon dioxide emissions, and the expected loss. The methodology considers the probability of occurrence of a set of seismic scenarios that reflect the seismic activity of the region. The performance of network links is quantified based on individual bridge performance evaluated through fragility analyses. The sustainability and risk depend on the damage states of both the links and the bridges within the network following an earthquake scenario. The time-variation of the sustainability metrics and risk due to structural deterioration is identified. The approach is illustrated on a transportation network located in Alameda County, California.

Assessment of Risk Using Bridge Element Condition Ratings

AbstractIn this paper, a methodology for quantifying lifetime risk of bridge superstructures is presented. The risk is quantified in terms of the expected direct and indirect losses. A scenario-based approach, which uses the Pontis element condition rating system, is used for identifying the expected losses. The deterioration process of bridge components regarding the transition between the condition states is modeled as a Markov process. In addition, a reliability-based approach is used to compute the probabilities of component and system failure, given the condition states. The methodology is illustrated on an existing bridge in Wisconsin. The expected losses associated with the flexural failure of girders are quantified in time. Furthermore, the time-variant risk-based robustness index is assessed.

Pre-Earthquake Multi-Objective Probabilistic Retrofit Optimization of Bridge Networks Based on Sustainability

Planning retrofit actions on bridge networks under tight budget constraints is a challenging process. Because of the uncertainties associated with this process, a probabilistic approach is necessary. In this paper, a probabilistic methodology to establish optimum pre-earthquake retrofit plans for bridge networks based on sustainability is developed. A multicriteria optimization problem is formulated to find the optimum timing of retrofit actions for bridges within a network. The sustainability of a bridge network and the total cost of retrofit actions are considered as conflicting criteria. The sustainability is quantified in terms of the expected economic losses. The uncertainties associated with seismic hazard and structural vulnerability are considered. The methodology is illustrated on an existing bridge network. Genetic algorithms are used to solve the multicriteria optimization problem. The effects of deterioration on bridge seismic performance are considered. The effects of the time horizon on the Pareto optimal solutions are also investigated.

Risk-Based Maintenance Optimization of Deteriorating Bridges

Risk-based performance measures integrate probability of component or system failure with the consequences of this event. In this paper, a novel risk-based maintenance optimization methodology for deteriorating bridges to find the optimum maintenance options and their timing is proposed. Finding the optimum maintenance types and schedule for different components of bridges is formulated as a multicriteria optimization in which the lifetime maximum value of expected losses associated with failure and the lifetime total expected maintenance cost are considered as the conflicting objectives. The risk-based maintenance approach accounts for different deterioration levels of bridge components and consequences of both component failure and system failure. The methodology is illustrated on a bridge superstructure. The effects of considered life span of the structure and availability of maintenance options on optimum solutions are also investigated.

Performance Indicators for Structures and Infrastructures

Design, assessment and prediction of the performance of structures and infrastructures based on component analysis have been the conventional methodologies enforced by the specifications. Nevertheless, system-based performance indicators can provide more efficiency and dependability in performance-based design, assessment, and prediction of structures and infrastructures. The objective of this paper is to provide a general overview of performance indicators applicable to civil structures and infrastructures. Definitions and formulations of selected performance indicators are presented. Information on what level (section, component, system, system of systems) these indicators are useful is provided. Interaction between life-cycle cost and lifetime performance is presented.