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Solutions to most practical numerical optimization problems must be evaluated for their performance over a number of different loading or operating conditions, which we refer here as scenarios. Therefore, a meaningful and resilient optimal solution must be such that it remains feasible under all scenarios and performs close to an individual optimal solution corresponding to each scenario. Despite its practical importance, multiscenario consideration has received a lukewarm attention, particularly in the context of multiobjective optimization. The usual practice is to optimize for the worst-case scenario. In this paper, we review existing methodologies in this direction and set our goal to suggest a new and potential population-based method for handling multiple scenarios by defining scenario-wise domination principle and scenario-wise diversity-preserving operators. To evaluate, the proposed method is applied to a number of numerical test problems and engineering design problems with a detail explanation of the obtained results and compared with an existing method. This first systematic evolutionary-based multiscenario, multiobjective optimization study on numerical problems indicates that multiple scenarios can be handled in an integrated manner using an evolutionary multiobjective optimization framework to find a well-balanced compromise set of solutions to multiple scenarios and maintain a tradeoff among multiple objectives. In comparison to an existing serial multiple optimization approach, the proposed approach finds a set of compromised tradeoff solutions simultaneously. An achievement of multiobjective tradeoff and multiscenario tradeoff is algorithmically challenging, but due to its practical appeal, further research and application must be spent. [ABSTRACT FROM AUTHOR]

Bridge restoration models are essential for assessing the functionality of bridges after extreme events, emergency response planning, and evaluating resilience and indirect losses. Most of the existing restoration models lack explicit evaluation of anticipated bridge functionality in terms of traffic restrictions on bridges, which is necessary for realistic road network modeling. Therefore, this paper proposes a decision tree based approach to determine potential traffic restrictions and their durations using empirical and expert opinion survey data on restrictions imposed on bridges after extreme events. The proposed methodology is applied in this paper to obtain seismic restoration models for bridges. Herein, three separate decision trees are developed to determine various traffic restrictions, anticipated for different levels of damage to bridge components, including bridge closure, lane closure, and speed/load restriction. Corresponding to each of the three traffic restriction decision trees, another decision tree is developed which determines the duration of the traffic restriction. The probabilistic seismic performance of a regional highway network in Memphis, Tennessee, is studied using the proposed decision trees. Additionally, HAZUS bridge restoration functions are also applied and the differences in the time evolving bridge level functionality estimates and their impacts on network performance are highlighted. [ABSTRACT FROM AUTHOR]

The prefabricated reinforced concrete (RC) hollow slab bridges, with the advantages of high quality, lower cost and shorter construction period, have been widely used for small-to-medium-span highway bridges in China. Because of environmental deterioration and traffic volume increases, the performance of the bridge system deteriorates gradually. Accurate bridge system evaluation can provide a reliable basis for maintenance and management. A bridge system is composed of multiple interrelated components, which makes the system reliability evaluation become a computationally intractable work. In this paper, an effective method was proposed to evaluate the system reliability of the prefabricated RC hollow slab bridge considering hinge joint damage based on the modified analytic hierarchy process (AHP). Considering the subjectivity of the traditional AHP method in constructing the judgment matrix, this paper proposed an objective construction method of the judgment matrix to modify the traditional AHP. The modified hinge plate method (MHPM) proposed by the previous research was utilized to analyze the effect of hinge joint damage on system reliability. In order to verify the applicability of the proposed system reliability evaluation method, a simply supported RC hollow slab bridge was selected as the case study and the system reliability indexes were compared with the traditional series and parallel methods. The results indicated that the traditional methods were either too conservative or too radical to objectively evaluate the actual system reliability level of the structure. In contrast, the proposed method in this paper was more suitable for evaluating the system reliability of such bridges, and more accurate in providing maintenance decision makers with a relatively reasonable bridge condition information. [ABSTRACT FROM AUTHOR]

In this paper, an approach for integrating the information obtained from structural health monitoring in a life-cycle bridge management framework is proposed. The framework is developed on the basis of life-cycle system performance concepts that are also presented in this paper. The performance of the bridge is quantified by incorporating prior knowledge and information obtained from structural health monitoring using Bayesian updating concepts. This performance is predicted in the future using extreme value statistics. Advanced modelling tools and techniques are used for the lifetime reliability computations, including incremental nonlinear finite element analyses, quadratic response surface modelling using design of experiments concepts, and Latin hypercube sampling, among other techniques. The methodology is illustrated on an existing bridge in the state of Wisconsin. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Summary: Inerter‐based dampers (IBDs) have been proposed to enhance the efficiency of conventional tuned mass dampers (TMDs) in controlling wind‐induced vibration of civil structures recently. In this paper, four different IBDs, with each featuring a specific combination of dashpot–spring elements in series or in parallel with the inerter device, are applied to control the vortex‐induced vibration (VIV) of long‐span bridges. The governing equations of the bridge–IBD system under the effect of VIV are established, and the strategy to optimize the IBD parameters is proposed. The performances of different IBDs in terms of mitigating the VIV response of the deck, the stroke of mass block, the static deformation of spring due to gravity, the reaction force of IBDs on the bridge deck, and the robustness of the system (the control efficiency against the deviation of design parameters from their optimal values) are systematically evaluated and compared. Through this comparative study, the superiorities of IBDs to conventional TMDs in bridge VIV control are illustrated, and two feasible layouts of IBDs that are suitable for bridge VIV control are suggested. On the basis of these results, the guideline for VIV‐resistance design of long‐span bridges with the help of IBDs is also proposed. [ABSTRACT FROM AUTHOR]

Owing to environmental and loading effects, complex processes of deterioration in structural performance will be encountered in the maintenance and management of long-span bridges during their service life. Therefore, the method of evaluation for acquiring the current status and trend in the deterioration of bridge performance is important. To improve the efficiency and objectivity of performance evaluations, the concept of standardization can be introduced to specify each step of the evaluation procedure. This paper presents a preliminary research framework for the standardization of performance evaluations for the Taizhou multi-pylon suspension bridge, which has special structural characteristics. This study is a part of a three-stage project on data standardization, evaluation, and retention. First, a framework with six core modules (action, structure, response, performance, indicator, and target) is established. Second, the relationship between these core modules and the performance evaluation procedure is discussed. Third, the content (e.g., definition and hierarchy) of each core module is described in detail. Finally, three examples (saddle sliding on top of middle steel pylon, concrete carbonation, and performance of middle pylon under extreme actions) are provided to demonstrate how the framework can be applied in performance evaluations of long-span bridges. [ABSTRACT FROM AUTHOR]

Input/output (I/O) devices such as a graphics processing unit and a solid-state drive are inserted into I/O slots of a host in data center platforms. With this sort of configuration the I/O devices are used exclusively by the host with resultant inefficient resource usage. In addition, the maximum number of I/O devices that can be assigned to each host is limited by the number of its I/O slots. This paper proposes a method to solve the resource usage inefficiency and assignment limitation by disaggregating I/O devices from hosts. An I/O device accommodated in a device pool is interconnected with multiple hosts by a standard Ethernet and can be flexibly assigned to one of them. Introducing assignment flexibility of I/O devices among hosts improves the resource usage efficiency and enables as many I/O devices as desired being assigned to each host. The authors further propose a method that enables an I/O device to be simultaneously shared among multiple hosts and multiple I/O packets to be aggregated into an Ethernet frame to suppress the performance overhead of the device disaggregation. Evaluation results showed that I/O devices that are compliant to PCI Express are shared with the overhead up to 27 percent. [ABSTRACT FROM AUTHOR]

The performance of existing bridges may deteriorate in time due to aggressive environmental or operating conditions in service, which may eventually cause changes in structural resistance and reliability beyond the baseline assumed for new ones. In addition, the increasing trend of live loads applied to the bridges, which has been reported in many researches, also contributes to the reduction of structural reliability. In order to perform time-dependent reliability assessment for aging bridges subjected to nonstationary loading process with improved efficiency, a simplified method is proposed in this paper, where lower dimensional integral is involved in the calculation of reliability. With the proposed method, time-dependent reliability of a real aging RC bridge is conducted, and the effect of nonstationarity in load intensity on structural reliability is investigated. It is found that structural reliability is sensitive to the increase of load intensity, and is less sensitive to the varying mechanism of load intensity. [ABSTRACT FROM AUTHOR]

Currently, it is a challenge to effectively assess the seismic performance of the high-speed railway bridge line. To figure it out, this paper discussed the applicability of the Pushover analysis in the seismic fragility of the high-speed railway bridge. As the piers are the core components to resist the earthquakes, a typical high-speed railway bridge line consisting of 22 piers was established by the finite element software OpenSees. The influences of the different pier height and sites on the fragility analysis of the pies were investigated. From the component level, the seismic performance of the high-speed railway bridge line was evaluated by the Pushover analysis. The results show that the seismic responses of the piers by the Pushover analysis are agreeable with those by the incremental dynamical analysis when the peak ground acceleration is less than 0.4g. The high piers have better seismic performance than the lower piers. The high-speed railway bridge line exhibits good seismic performance under the 7-degree design earthquake (0.15g) and the 8-degree low-level earthquake (0.10g) but may be severely damaged under the 9-degree low-level earthquake (0.40g). [ABSTRACT FROM AUTHOR]

Even though accurate structural models have been developed for the performance of corroded structures subjected to monotonic flexure and/or shear, studies on seismic performance that include corrosion damage are scarce. For the lifetime assessment of structures in aggressive environments and earthquake-prone regions, the effects of corrosion on seismic performance need to be taken into consideration. Whereas the seismic demand depends on the results of seismic hazard assessment, the deterioration of seismic capacity depends on the environmental hazard assessment. The analysis of the life-cycle reliability of corroded reinforced concrete (RC) structures under earthquake excitations is the topic of this paper. It includes (a) estimation of the seismic capacity of corroded RC components; (b) seismic and airborne chloride hazard assessment and (c) life-cycle seismic reliability of bridges with corrosion damage. In particular, this paper introduces the visualisation of corrosion process in RC members using X-ray for modelling the spatial variability of rebar corrosion. A novel computational procedure to integrate the probabilistic hazard associated with airborne chlorides into life-cycle seismic reliability of bridge piers is presented. [ABSTRACT FROM AUTHOR]

This paper describes the performance of stainless-steel micro-relays, with platinum–rhodium metal foil contact elements, in handling high-power RF signals. The electrical and thermal responses are described for electrostatically actuated three-terminal micro-relays that are directly assembled on printed circuit boards. The preliminary designs have footprints of 6.4 \ \mm^2. Fabricated relays have 90-V turn-on (pull-down) voltage. The down-state insertion loss and up-state isolation were better than 0.2 and 25 dB over the band of dc–5 GHz, respectively. The devices can accommodate incident RF power up to 18.5 W at 3 GHz when cooled by forced air from a mini-fan. [ABSTRACT FROM PUBLISHER]

This paper presents a comprehensive overview of recent developments in the performance evaluation and flexural response of existing bridges from fundamental concepts to advanced topics. The focus is particularly on the structural evaluation to enhance the quality assessment of constructed bridge superstructures, taking into account a synthesis of the most important contributions to the flexural behavior of existing bridges, such as dynamic responses and lateral load distributions. This state-of-the-art paper provides a critical review of published literature and existing assessment methodologies in conjunction with corresponding analysis techniques, including technical comments on the code provisions. Detailed descriptions of the important parameters influencing flexural responses of existing bridges are discussed, such as the geometric effect, loading configuration, present condition of a bridge, and contribution of secondary structural elements. The review also includes the investigation methodologies, namely, the diagnostic and proof load tests. Finally, the current research needs to further advance the performance evaluation technologies for existing bridge superstructures are recommended. [ABSTRACT FROM AUTHOR]

A general methodology for lifetime performance analysis of existing prestressed concrete girder bridges is presented. Only the superstructure components (slab and girders) are considered. The framework for the methodology is established by identifying four distinct categories: limit state equations, random variables, deterministic parameters, and constant coefficients. The limit state equations are derived by strictly adhering to the load and capacity formulas and requirements set forth in AASHTO specifications. Generality is pursued by establishing parametric limit state equations such that the formulas are applicable to any type of prestressed concrete bridge having similar superstructure components. For time-variant performance analysis, special emphasis is placed on the corrosion penetration modeling in prestressed concrete girders. The developed methodology is applied to seven existing bridges located in Colorado to obtain the lifetime performance of these prestressed concrete girder bridges in the bridge network. Once the values associated with random variables, deterministic parameters, and constant coefficients are assigned, component reliability indices for the slab and the girders are calculated for each bridge. Detailed results are presented for an individual bridge, whereas the lifetime reliability profiles are presented for selected bridges. The focus of the paper is on the formulation and the overall methodology rather than analysis of the results. [ABSTRACT FROM AUTHOR]

In the context of sustainability, life cycle approaches are becoming increasingly popular for the assessment of potential impacts of a product or a system, from raw materials production to decommissioning and end-of-life processes. In relation to highway bridges, lifetime analysis implies consideration of the way the bridge is maintained over the lifespan of the analysis. Different maintenance strategies can be defined depending on the policy followed by highway administrations, which are usually subject to budget restraints. An overview of different European practices in the maintenance of highway bridges is provided in this paper; then, a methodology for life cycle analysis of bridges is presented, which enables assessment of the influence of different strategies of maintenance of highway bridges, in terms of environmental burdens, and direct and indirect costs over the lifespan of the bridge. The discussion is based on a case study of a composite bridge crossing a dual carriageway. The methodology presented in this paper is part of a research work carried out in the framework of the European research project SBRI: Sustainable Steel-Composite Bridges in Built Environment. [ABSTRACT FROM AUTHOR]

A large-scale, two-span bridge model constructed by assembling precast elements was tested under a series of bi-axial ground motions simulated on a shake table at the Earthquake Engineering Laboratory at the University of Nevada, Reno. The response of the bridge was estimated before the tests using a three-dimensional computational model developed in OpenSees software. After the tests, key measured seismic responses were compared to those predicted by the computational model to assess the modeling assumptions. Relatively large errors for the displacements, base shears, and hysteretic response of the bridge were observed. The influence of the earthquake loading, materials, connectivity of the precast elements, and boundary conditions in the computational model on the errors are discussed in this paper. Future modeling directions are proposed to reduce these errors. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Journal of Civil Engineering is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The objective of the national agency for road and water infrastructure in the Netherlands is to deliver best service to the public at lowest life cycle cost, given public acceptable risk. This requires a sound and well-structured system of management and maintenance. Such a system consists of elements such as reliable asset data, long-term performance based maintenance programmes, clear steering objectives and transparent procurement strategies. Asset management will make it possible to show what network performance can be achieved, at which costs and with which associated risks. A model defining an asset owner role, an asset manager role and a service provider role was chosen as a governing principle for the design of the asset management process. The design of the process described in the paper sets the boundary conditions to carry out projects with the minimum amount of hindrance for the user while involving the market in the best possible way. [ABSTRACT FROM AUTHOR]

In this paper, artificial neural networks (ANNs) are used to develop an efficient method for rapid and approximate force response analyses of a bridge population. The single-span reinforced concrete T-beam bridge population in Pennsylvania State is taken as a particular case study. First, a statistical analysis is conducted to examine implicit and explicit dependencies between various geometrical and structural parameters of the bridges, and the governing bridge parameters are identified along with their ranges of variation within the population. Then, a set of sample bridges are randomly generated using different combinations of the governing parameters within their predefined ranges of variation. An exact finite element analysis is implemented for each sample bridge, and the maximum moment and shear responses in beams are obtained at critical locations under various combinations of standard truck loads. An ANN is implemented to learn the relationship between the bridge parameters (inputs) and responses (outputs) based on the sample set and to make predictions for other bridges that are not present in the set. The performances of a variety of different ANN architectures are tested, and their prediction capabilities are measured and compared. [ABSTRACT FROM AUTHOR]

This paper presents an experimental study to investigate the performance of shape memory alloy (SMA) restrainers for mitigating the pounding and unseating of highway bridges when subjected to seismic excitations. Mechanical property tests of the SMA wire used in the restrainers are conducted first to understand the pseudo-elastic characteristics of the material. Then, a series of shaking table tests are carried out on a highway bridge model. The structural responses of the highway bridge model equipped with SMA restrainers, installed in the form of deck-deck and deck-pile connections, are analyzed and compared with the uncontrolled structures. The test results of this study indicate that the SMA restrainers are not only effective in preventing unseating but also in suppressing the seismic-induced pounding of the highway bridge model used in this study. [ABSTRACT FROM AUTHOR]

Many bridges in Algeria were constructed without taking into account the seismic effect in the design. The implantation of a new regulation code RPOA-2008 requires a higher reinforcement ratio than with the seismic coefficient method, which is a common feature of the existing bridges. For better perception of the performance bridge piers and evaluation of the risk assessment of existing bridges, fragility analysis is an interesting tool to assess the vulnerability study of these structures. This paper presents a comparative performance of bridge piers designed with the seismic coefficient method and the new RPOA-2008. The performances of the designed bridge piers are assessed using thirty ground motion records and incremental dynamic analysis. Fragility curves for the bridge piers are plotted using probabilistic seismic demand model to perform the seismic vulnerability analysis. The impact of changing the reinforcement strength on the seismic behavior of the designed bridge piers is checked by fragility analysis. The fragility results reveal that the probability of damage with the RPOA-2008 is less and perform well comparing to the conventional design pier. [ABSTRACT FROM AUTHOR]

In this paper, an extended Cloud analysis method is developed for seismic fragility assessment of existing highway bridges in the southeast Queensland region. This method extends the original Cloud analysis dataset by performing scaled Cloud analyses. The original and scaled Cloud datasets are then paired to generate seismic fragility curves. The seismic hazard in this region is critically reviewed, and the ground motion records are selected for the time-history analysis based on various record selection criteria. A parametric highway bridge model is developed in the OpenSees analysis software, and a sampling technique is employed to quantify the uncertainties of highway bridges ubiquitous in this region. Technical recommendations are also given for the seismic performance evaluation of highway bridges in such low-to-moderate seismic zones. Finally, a probabilistic fragility study is conducted by performing a total of 8000 time-history analyses and representative bridge fragility curves are generated. It is illustrated that the seismic fragility curves generated by the proposed extended Cloud analysis method are in close agreement with those which are obtained by the rigorous incremental dynamic analysis method. Also, it reveals that more than 50% of highway bridges existing in southeast Queensland will be damaged subject to a peak ground acceleration of 0.14 g. [ABSTRACT FROM AUTHOR]

The design and construction of bridge systems with long-term durability and low maintenance requirements is a significant challenge for bridge engineers. One possible solution to this challenge could be through the use of new materials, e.g., fiber-reinforced polymer (FRP) composites, with traditional materials that are arranged as an innovative hybrid structural system where the FRP serves as a load-carrying constituent and a protective cover for the concrete. This paper presents the results of an experimental investigation designed to evaluate the performance of a 3/4 scale hybrid FRP-concrete (HFRPC) bridge deck and composite connection under sustained and repeated (fatigue) loading. In addition, following the sustained-load and fatigue portions of the experimental study, destructive testing was performed to determine the first strength-based limit state of the hybrid deck. Results from the sustained-load and fatigue testing suggest that the HFRPC deck system might be a viable alternative to traditional cast-in-place reinforced concrete decks showing no global creep behavior and no degradation in stiffness or composite action between the deck and steel girders after 2 million cycles of dynamic loading with a peak load of 1.26 times the scaled tandem load (TL). Furthermore, the ultimate strength test showed that the deck failed prior to the global superstructure at a load approximately six times the scaled TL. [ABSTRACT FROM AUTHOR]

In this paper, an embedded electromagnetic bandgap structure is proposed for harmonic filtering of differential signal's undesired common mode components. Rather than use lumped circuit components and likely causing some degradation to the intended high speed differential signal, the embedded planar common mode filter causes no degradation to the intended signal, and enhances the signal integrity and electromagnetic compatibility performance of the system. Single ended and differential traces are considered and the impact of the common mode filtering is measured in terms of mixed mode scattering parameters and eye diagram metrics. The systematic procedure to design such a structure is outlined, and its design robustness is also verified. [ABSTRACT FROM AUTHOR]

A general method for lifetime performance analysis of existing steel girder bridges is presented. Only the superstructure components are considered. The formulation is established by identifying four distinct categories: limit state equations, random variables, deterministic parameters, and constant coefficients. The limit state equations are derived by strictly adhering to the load and capacity formulas and requirements set forth in AASHTO specifications. Generality is pursued by establishing parametric limit state equations such that the formulas are applicable to any type of steel bridge having similar superstructure components. The application of the developed formulation to lifetime performance analysis of four steel girder bridges located in an existing bridge network in Colorado is also presented. Performance analysis results are presented in two main categories: initial reliability indices and lifetime reliability profiles. Once the values associated with random variables, deterministic parameters, and constant coefficients are assigned, component reliability indices for the slab and the girders are calculated for each bridge. Detailed results are presented for an individual bridge and the lifetime reliability profiles are presented for two bridges. For time-variant performance analysis, special emphasis is placed on the corrosion penetration modeling in the girders. An attempt has been made to adopt such models to the atmospheric and environmental conditions of Colorado. Limitations to such an approach are also described. The focus of the paper is on the formulation and the overall methodology rather than the analysis of the results. [ABSTRACT FROM AUTHOR]

In an effort to assess the constructability and performance of bridges with fiber-reinforced polymer (FRP) composite decks, the short-term and long-term responses of a 207 m, five-span bridge retrofitted with four different FRP panel systems were monitored. The overall aspects of the panel systems, connection details, and construction techniques are presented prior to presentation of the observed and measured responses. Key design parameters (impact factors, girder distribution factors, and level of composite action) for FRP and reinforced concrete decks are evaluated. This paper demonstrates that FRP replacement decks are a viable alternative to reinforced concrete decks and identifies the differences in performances of various FRP deck systems. Two of the FRP panel systems were found to perform considerably better than the other deck systems. Issues that may reduce the service life of FRP deck systems are presented and discussed. [ABSTRACT FROM AUTHOR]

• A method for evaluating the performance of train-bridge systems is proposed. • Both random uncertainty and weighted evaluation indexes can be considered. • The performance state of train-bridge systems is classified and defined. • The weightings of evaluation indexes for train-bridge systems are quantified. • The proposed method can more accurately describe the system performance. In this paper, a practical methodology for evaluating the dynamic performance of train-bridge systems is presented, which incorporates both random uncertainty and the weighting of evaluation indexes. Firstly, a train-bridge stochastic model is established by combining an existing train-bridge deterministic model with the Generalized F-discrepancy (GF-discrepancy) minimized point selection strategy and the probability density evolution method (PDEM). The model enables the accurate and efficient quantification of the variability of any dynamic response quantity of interest in the train-bridge system. Building on this foundation, an assessment model based on the multi-layer fuzzy comprehensive evaluation method is developed to determine the possibility of the train-bridge stochastic system in different performance states with consideration of the weighted evaluation indexes. In the assessment model, the main criteria of the train-bridge system are collected, classified, and further structured a logical hierarchical framework, and the weightings of the criteria are solved by analytic hierarchy process method and entropy weighting method. As demonstrated by a numerical example, the proposed method can properly consider system uncertainties, appraisal hierarchy, and the weightings of evaluation indexes, which helps identify critical evaluation indexes and improve evaluation reliability. The proposed approach can provide a useful tool for the performance evaluation of train-bridge systems. [ABSTRACT FROM AUTHOR]

Deteriorated facility maintenance is a critical social issue in advanced countries. Its cost increases when considering the social consequences in terms of asset value and direct maintenance costs. Data from Korea's Ministry of Land, Infrastructure, and Transport shows that there were 3454 bridges aged 30 years or over in Korea in 2017; this number will increase to 10,961 by 2027. In thirty years, maintenance costs will be incurred for more than 32,000 old bridges in Korea. These trends are also observed in the US, Japan, and Korea. Diverse studies have been conducted to predict the residual life of old bridges via bridge performance evaluation and load-carrying capacity assessments. However, criteria for evaluating bridge performance and verifying the effect of bridge maintenance are yet to be established due to two reasons. First, most studies on performance evaluation, maintenance, and rehabilitation techniques have been performed on limited specimens from building elements or through small-scale simulations that do not reflect the deterioration factors of complex materials in diverse environments. Second, the performance evaluation of bridges is difficult compared to quantitative state evaluations. As a method of predicting the future performance of aged concrete bridges, it is effective to understand the actual aged bridges through experiments, and this study intends to propose the method. [ABSTRACT FROM AUTHOR]

Transportation infrastructure has been identified by the US Department of Homeland Security as one of sixteen critical infrastructure systems essential to the well-being of modern societies. In this study, we propose a resilience-based framework for mitigating risk to surface road transportation networks. We utilize recent developments in modern network theory to introduce a novel metric based on system reliability and network connectivity to measure resilience-based performance of a road transportation network. The formulation of this resilience-based performance metric (referred in the paper as WIPW), systematically integrates the network topology, redundancy level, traffic patterns, structural reliability of network components (i.e. roads and bridge) and functionality of the network during community’s post-disaster recovery, and permits risk mitigation alternatives for improving transportation network resilience to be compared on a common basis. Using the WIPW as a network performance metric, we propose a project ranking mechanism for identifying and prioritizing transportation network retrofit projects that are critical for effective pre-disaster risk mitigation and resilience planning. We further present a decision methodology to select optimal solutions among possible alternatives of new construction, which offer opportunities to improve the resilience of the network by altering its existing topology. Finally, we conclude with an illustration that uses the WIPW as the performance metric to support risk-based mitigation decisions using a hypothetical bridge network susceptible to seismic hazards. [ABSTRACT FROM AUTHOR]

This paper describes health examination and remaining service life prediction procedures for an aged reinforced concrete (RC) T-girder bridge via visual inspection data. The Bridge Management System (J-BMS) that was previously developed by the authors, and which is capable of forecasting the deterioration process of existing bridge members, was applied to evaluate the safety indices (health score) and remaining service life of the subject bridge based on these test results. Using these procedures, the remaining service life of an aged RC-T girder bridge can quantitatively be estimated by applying the bridge rating expert (BREX) system, which is a subsystem of the J-BMS that incorporates field inspection data. In this study, visual inspection was carried out on an aged bridge by professional visual inspectors, during which all variations of the inspection results were evaluated using a five-step questionnaire. Additionally, it was found that health score (safety indices) and remaining service life predictions were influenced by the learning (supervised) data selection. [ABSTRACT FROM AUTHOR]

The management of existing concrete bridges has become a major social concern in many developed countries due to the large number of bridges exhibiting signs of significant deterioration. This problem has increased the demand for effective maintenance and renewal planning. In order to implement an appropriate management procedure for a structure, a wide array of corrective strategies must be evaluated with respect to not only the condition state of each defect but also safety, economy and sustainability. This paper describes a new performance evaluation system for existing concrete bridges. The system evaluates performance based on load carrying capability and durability from the results of a visual inspection and specification data, and describes the necessity of maintenance. It categorizes all girders and slabs as either unsafe, severe deterioration, moderate deterioration, mild deterioration, or safe. The technique employs an expert system with an appropriate knowledge base in the evaluation. A characteristic feature of the system is the use of neural networks to evaluate the performance and facilitate refinement o f the knowledge base. The neural network proposed in the present study has the capability to prevent an inference process and knowledge base from becoming a black box. It is very important that the system is capable of detailing how the performance is calculated since the road network represents a huge investment. The effectiveness of the neural network and machine learning method is verified by comparing diagnostic results by bridge experts. [ABSTRACT FROM AUTHOR]

Abstract: WSN signal obstruction from various bridge components, including girders, bracings and connectors, can affect the performance and reliability of wireless communication. Although the placement of sensor nodes is essential for forming a mesh or ad-hoc network, there are no quantitative approaches related to the optimal separation distance of each node and the corresponding signal quality. This paper reports the results of an experimental evaluation of the WSN performance in the obstructed environment of a bridge structure. The performance criteria, such as thickness of bridge components, material types and location, were analyzed to determine quantitatively the packet reception rate and allowable separation distance during wireless communication. In addition, a case study was conducted to identify the practical implication that an obstructed environment degrades the communication range and WSN reliability according to the performance criteria. The results show that the WSN placement mainly depends on the material type and object thickness. [Copyright &y& Elsevier]

Copyright of Baltic Journal of Road & Bridge Engineering (Baltic Journal of Road & Bridge Engineering) is the property of Baltic Journal of Road & Bridge Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Baltic Journal of Road & Bridge Engineering (Baltic Journal of Road & Bridge Engineering) is the property of Baltic Journal of Road & Bridge Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract: Past failure of coastal bridges during hurricanes has revealed the vulnerability of these structures to wave and storm surge loading, thus signifying the need for reliability assessment of coastal bridges to provide a basis for hurricane risk assessment and mitigation. Such a reliability assessment requires probabilistic estimation of the capacity and demand of the structure, which are often conveniently decoupled to support risk assessment of existing bridges as well as performance based design or retrofit. This paper presents a new approach for probabilistic analysis of limit state capacities for bridge systems, in which local response quantities from numerical simulations are mapped to global performance measures, such as system strength and stiffness loss. Four different configurations of a case study bridge are analyzed to derive probabilistic models of the limit state capacities, revealing the significant bridge component demand parameters that contribute to the global (system) damage levels and the mathematical form of the limit state capacities, along with uncertainty quantification. Such models can be used in reliability assessment of coastal bridges and extended to evaluate the effectiveness of alternative retrofit measures proposed for unseating prevention. The proposed approach for global performance assessment complements emerging interests in multi-hazard analysis and system reliability of bridges by providing a new perspective on identifying the joint local damages which affect global behaviors that relate to practical decision making on post-event bridge functionality. [Copyright &y& Elsevier]

Abstract: A large number of post-tensioned prestressed concrete segmental bridges are being constructed worldwide. Use of different materials and shear keys will have varying effects on the performance of segmental girders even during the service load. The type of joints, quality of joint, degree of mechanical actions and the joint materials will contribute to the variation in the behaviour of the segmental girders. Hence, the need for investigation on the epoxy jointed segmental box girder and dry jointed segmental box girder becomes necessary. This paper presents the experimental investigations carried out in laboratory environment on a scaled model of a simply supported precast post-tensioned box-girder bridge deck that is cast using segmental construction method. Performance of box-girders with dry and epoxy joints is evaluated under static and cyclic loading. It is observed from the results that the flexural strength of dry jointed specimen is less than the epoxy joint due to high concentration of rotation and deflection at individual joints of segmental girder. Upto design load, segmental box girder specimen with dry and epoxy joints behaved like monolithic beam. However, it is found from the study that first joint opening load of the dry jointed specimen is 27% less than the epoxy jointed specimen due to lack of resistance to tension between the joints. Due to high concentration of rotation and deflection at individual joints in the dry jointed specimen, the maximum load and failure load are 8.6% and 16.7% less than that of the epoxy jointed specimen. The study will help in understanding the role of type of joint and the material used on the performance of the segmental bridges. [Copyright &y& Elsevier]

Abstract: Studies associated with distributed civil infrastructure systems are usually very demanding from a computational point of view, especially when they involve life-cycle analysis, uncertainty, and optimization. For this reason, computational tools that enhance the efficiency of the analysis and make it feasible for complex practical applications are of utmost importance. In this paper, a computational technique for the efficiency enhancement of bridge network life-cycle analysis under uncertainty is presented and its impact in terms of CPU time reduction is investigated. The proposed technique consists in the joint use of random field theory and probabilistic reliability models for the simulation of the individual bridge service states over the life-cycle of the infrastructure. This random field based approach is extremely efficient and takes simultaneously into account the deterioration in time of the bridge reliability and the correlation in space of the service states of bridges belonging to the same transportation network. Compared to other techniques previously used to perform the same task, the proposed methodology is theoretically more solid and improves the computational efficiency by more than two orders of magnitude. A numerical example is provided to validate the proposed technique. Moreover, a second example involving the life-cycle performance analysis of a complex bridge network in Santa Barbara, CA, is presented. [Copyright &y& Elsevier]

Abstract: This paper focuses on conducting lifetime performance assessment and management of aging steel bridges under fatigue by integrating three prediction models: fatigue reliability model (FRM), crack growth model (CGM), and probability of detection (PoD) model. A novel approach using these models is proposed for planning interventions on fatigue sensitive structures. Based on information from field monitoring and/or non-destructive evaluation, prediction models are developed to (a) estimate the time-dependent fatigue performance using FRM, (b) provide the time-dependent crack growth using CGM, and (c) quantify the detection capability associated with fatigue cracks using PoD model. In order to assess and manage bridge fatigue life, the three models are combined based on two parameters (i.e., number of cycles, crack size). As an illustration, the combined approach is used for fatigue assessment and management of an existing bridge. [Copyright &y& Elsevier]

Abstract: Unseating of bridges during earthquakes results from the failure of bearings and insufficient seat length. In case of elastomeric bearings, large deformations of the superstructure occur, under severe earthquake ground motions and additional protection measures are necessary. The combination of a displacement restraining device with the elastomeric bearing can prevent bearing failure. This paper evaluates the performance of four different types of protection devices to limit the displacement of the superstructure during earthquakes: (1) rigid stopper device, (2) yielding stopper device, (3) steel restrainer, and (4) superelastic shape memory alloy (SMA) restrainer. Analytical models for all the protection devices have been developed and seismic response of an existing bridge with elastomeric bearings and different protection devices has been evaluated for five strong ground motion records scaled in the frequency domain. The results show that all the protection devices have comparable performance in preventing the failure of bearing during an earthquake. [Copyright &y& Elsevier]

• Controlled Rocking Dual-Fused Bridge System is an efficient SFRS for bridges. • EEDP methodology perfectly predicts the behavior of the CRDFB system. • Engineers can design the CRDFB system with simple hand calculation and no iteration. • The CRDFB system meets three tiers of performance at different shaking intensities. It is crucial for highway bridges to remain operational after strong earthquakes as they are critical infrastructures to transport resources. In this study, an innovative seismic-resilient bridge structural system, named controlled rocking dual-fused bridge (CRDFB) system, is proposed. The CRDFB system is designed to dissipate the earthquake energy by the use of replaceable Lead-Extrusion Dampers (LEDs) at the base of the rocking piers. The state-of-the-art Equivalent Energy Design Procedure (EEDP) is adopted and modified to design the CRDFB system to achieve different performance at different levels of shaking intensities. The proposed step-by-step EEDP allows engineers to design the CRDFB system to achieve the desired performance objectives with simple hand calculations and without iterations. A 2-span and a 3-span CRDFB prototypes located in Vancouver, Canada, are designed using the proposed EEDP. To validate the performance of the proposed CRDFB system, advanced three-dimensional analytical models of prototypes are developed using OpenSees and subjected to a broad array of two-dimensional and three-dimensional nonlinear time history analyses. Simulation results show that CRDFB prototypes can successfully achieve the targeted performance, as specified by EEDP design, at different shaking intensities. Hence, the proposed CRDFB system can be designed efficiently using the EEDP design procedure outlined in this paper, and be used as an efficient, reliable, and resilient seismic force-resisting bridge system for high seismic zones. [ABSTRACT FROM AUTHOR]

Assessment of resilience for engineered systems has drawn ample attention from the engineering community in recent years. It has resulted in a significantly large body of literature focusing on pertinent areas of resilience. This article provides a systematic and comprehensive review of the literature addressing resilience assessment of bridges and bridge networks under single hazard and multihazard conditions. Though not much work been performed yet on multihazard resilience of bridges, relevant aspects including combinations of multiple hazards for bridge performance evaluation, methods for loss assessment and approaches taken for post-event recovery are discussed. Furthermore, maintenance is a key component if resilience is assessed in a life-cycle framework. Hence, available maintenance plans and strategies and their probable applications for bridges and bridge networks are discussed. The article concludes with a discussion on the need for further research in the focus area and challenges involved with the same. [ABSTRACT FROM AUTHOR]

A fully integral bridge that is restrained at both ends by the abutments has been proposed to form a monolithic rigid frame structure. Thus, the feasible horizontal force effect due to an earthquake or vehicle braking is mainly prevented by the end-restraining abutments. In a recent study, a fully integral bridge with appropriate end-restraining abutment stiffness was derived for a multispan continuous railroad bridge based on linear elastic behavior. Therefore, this study aims to investigate the nonlinear behavior and seismic capacity of the fully integral bridge and then to assess the appropriate stiffness of the end-restraining abutment to sufficiently resist design earthquake loadings through a rigorous parametric study. The finite element modeling and analyses are performed using OpenSees. In order to obtain the force-deflection curves of the models, nonlinear static pushover analysis is performed. It is confirmed that the fully integral bridge prototype in the study meets the seismic performance criteria specified by Caltrans. The nonlinear static pushover analysis results reveal that, due to the end-restraining effect of the abutment, the lateral displacement of the fully integral bridge is reduced, and the intermediate piers sustain less lateral force and displacement. Then, the sectional member forces are well controlled in the intermediate piers by a proper application of the end-restraining abutments. [ABSTRACT FROM AUTHOR]

A newly developed passive device that provides negative stiffness has been implemented within a quarter-scale highway bridge model and subjected to seismic loading via shake table testing. Details of the experimental results and their comparison with numerical simulations under a wide range of ground motions are presented. In addition, performance indices were developed to systematically evaluate the relative performance of different isolation system configurations that employ combinations of positive and negative stiffness as well as various levels of damping. Further, the influence of boundary conditions (rigid versus flexible bridge piers) on the effectiveness of employing negative stiffness devices has been evaluated. [ABSTRACT FROM PUBLISHER]

Vehicular accidents involving tanker trucks may initiate devastating fires that can cripple a steel plate girder bridge. An observation of web shear buckling in one case study leads to a discussion on the existing understanding of this phenomenon. A closer look at the contribution of the transverse stiffeners to postbuckling shear capacity focuses on the effects of utilizing diagonal orientations of the stiffeners, as well as providing thermal insulation for the stiffeners alone. It was found that the diagonal stiffener models do not offer much improvement to the postbuckling shear strength compared to the use of the traditional vertical intermediate stiffener. Given the complexity of attaching a diagonal stiffener, it appears that the vertical stiffener is the better option. Further, providing fire resistance solely for the stiffeners was found to offer a minimal increase in the postbuckling shear strength at elevated temperatures. [ABSTRACT FROM AUTHOR]

Bridges constitute a substantial and vital part of any transport infrastructure system. The functionality of the system is therefore reliant on the asset management strategies adopted for its bridges. To understand and manage bridge performance, data of appropriate quality has to be collected in a cost-efficient way and closely linked to the decisions made with it. To ensure a coherent approach, a data collection strategy for asset management of road bridges has been developed in this study. In the strategy, a combined risk and criticality-based approach is used to prioritise each bridge and to assign it to one of three data collection levels comprising core, intermediate and advanced. For each collection level, the strategy provides guidance on the type of data to collect, the accuracy and precision required in the data collection process, the frequency of inspections, and the recommended collection techniques to be used, including visual inspection, non-destructive evaluation and structural health monitoring. The strategy will help asset managers to develop a deeper level of knowledge on the bridges that have the greatest impact on the system functionality and to collect data of the required quality needed for the decisions they make. [ABSTRACT FROM AUTHOR]

Research has been carried out to evaluate the structural behavior and influence of aging on a century-old steel railroad truss bridge. The structure is located in Connecticut and services a large number of trains traveling into and out of New York City. The trusses are made of built-up members, with either multiple eyebars or laced channel sections. All panel point connections are joined with true pins and the interior panels are indeterminate. The bridge had experienced problems relating to the lateral shifting of some of the middepth pins. This study was carried out to evaluate the structural behavior and live load distribution throughout the bridge. A major component of the research involved extensive field monitoring. The results show that the actual live load distribution is significantly different than expected from conventional analytical approaches that were most likely used in the original design. The load distribution in multiple eyebar elements is far from uniform, and the distribution of shear through indeterminate panels is significantly different than expected from a normal truss analysis. Significant out-of-plane bending was found in the truss due to floorbeam end rotations, which is thought to be the major factor that is causing the pins to move. The study shows the necessity of using field monitoring to better understand the behavior of older bridges prior to the design of renovation approaches. [ABSTRACT FROM AUTHOR]

Tech 21 is the third all-composite vehicular bridge installed in the United States. The deck has sandwich configuration with a center core made by bonding orthotropic fiberglass and polyester tubes. The three trapezoidal beams supporting the deck were fabricated using E-glass fibers with polyester resin. Each beam was fabricated as an integral unit with its deck section to facilitate transportation to the site, erection, and construction. The two-lane bridge is the first fully instrumented all-composite vehicular bridge, including an extensive health-monitoring system installed during its fabrication. A nearly four-year long continuous monitoring was carried out to demonstrate the performance of the bridge. Field monitored information was studied to evaluate the behavior and durability of composites in the harsh infrastructure environment. This evaluation determines the level of confidence in the long-term field benefits of composite materials and technology. [ABSTRACT FROM AUTHOR]