Showing papers in "Structure and Infrastructure Engineering in 2010"
TL;DR: In this paper, a comprehensive model to quantify disaster resilience of systems that is defined as the capability to sustain functionality and recover from losses generated by extreme events is presented. And the model combines loss estimation and recovery models and can be applied to critical facilities (e.g. hospitals, military buildings, etc.).
Abstract: This paper presents a comprehensive model to quantify disaster resilience of systems that is defined as the capability to sustain functionality and recover from losses generated by extreme events. The model combines loss estimation and recovery models and can be applied to critical facilities (e.g. hospitals, military buildings, etc.), as well as utility lifelines (e.g. electric power systems, transportation networks, water systems etc.) that are crucial to the response of recovery processes, decisions and policies. Current research trend leads toward the definition of complex recovery models that are able to describe the process over time and the spatial definition of recovery (e.g. meta-models for the case of health care facilities). The model has been applied to a network of hospitals in Memphis, Tennessee. The resilience framework can be used as a decision support tool to increase the resilience index of systems, such as health care facilities, and reduce disaster vulnerability and consequences.
453 citations
TL;DR: The most relevant seismic vulnerability and risk analysis methods are discussed and compared in this article using, as a pilot urban area, the city of Barcelona, Spain, where risk studies have been carried out over the last 15 years in the framework of different research projects.
Abstract: The most relevant seismic vulnerability and risk analysis methods are discussed and compared in this article using, as a pilot urban area, the city of Barcelona, Spain, where risk studies have been carried out over the last 15 years in the framework of different research projects. Most of the buildings in Barcelona, which have unreinforced masonry structure or reinforced concrete structure with waffled slab floors, show a high degree of vulnerability to earthquakes. The physical seismic risk but also the socio-economic implications of risk are considered in the article. The robustness of the innovative holistic approach, based on indicators related to the physical exposure, the social fragilities and the lack of resilience of urban area, is also proved. Using a geographic information system (GIS), the seismic risk results are described by means of scenarios of expected losses, but also as scenarios of probabilities of occurrence of predefined damage states.
157 citations
TL;DR: In this paper, the authors describe the technical characteristics of the microwave interferometer and the results of laboratory tests carried out to evaluate the actual displacement sensitivity of the equipment and discuss the application of the sensor to the measurement of ambient vibration response on a concrete bridge.
Abstract: Recent progress in radar techniques and systems has led to the development of a microwave interferometer, potentially suitable for non-contact vibration monitoring of civil engineering structures. The main characteristic of the new radar system, named IBIS-S, is the possibility of simultaneously measuring the (static or dynamic) displacement at several points of a structure with high sensitivity. The paper first describes the technical characteristics of the microwave interferometer and the results of laboratory tests carried out to evaluate the actual displacement sensitivity of the equipment. Subsequently, the application of the sensor to the measurement of ambient vibration response on a concrete bridge is presented and discussed.
145 citations
TL;DR: In this paper, a track degradation model based on track geometry and track geometry is proposed to predict railway track degradation. But the model is not suitable for the use of railway track maintenance programmers.
Abstract: There is a need among railway track maintenance programmers for a better understanding of the long-term behaviour of railway track systems and for improved predictive techniques. The use of accurate techniques to predict railway track conditions increases track safety and maintenance effectiveness. The aim of this research is to improve current track deterioration modelling techniques using a comprehensive field investigation. Statistical and engineering approaches are adapted for this research and comprehensive track field data is collected and analysed over a period of 2 years on approximately 100 km of railway line. Parameters that influence track degradation, including loading conditions, track maintenance status and track quality, are investigated, leading to the development of correlations between the effective parameters and the track degradation. These constructed correlations are then used to develop a new track degradation model in two formats. One format, based on track geometry, relies on data...
100 citations
TL;DR: In this paper, a simulation-based study is performed to evaluate the socioeconomic effect of seismic retrofit of bridges using the California Department of Transportation (Caltrans) Los Angeles area highway network as the testbed.
Abstract: A simulation-based study is performed to evaluate the socio-economic effect of seismic retrofit of bridges using the California Department of Transportation (Caltrans) Los Angeles area highway network as the testbed. 47 scenario earthquakes that represent the regional seismic hazard, consistent with the US Geological Survey (USGS) hazard map, are considered. Two sets of bridge fragility curves, before and after seismic retrofit, are used to simulate the seismic performance of the network in both cases. Analysis estimates the total social cost arising from driver delay and loss of opportunity in the degraded network. The benefit of seismic retrofitting is computed in present values as equal to the total future economic losses avoided from social cost and repair/restoration cost over the remaining bridge service lives. Estimated benefit is compared with the retrofit cost to investigate the benefit-cost ratio. Study shows that from the Caltrans point of interest, bridge seismic retrofit is cost-effective whe...
97 citations
TL;DR: In this article, the authors review the work done by the authors and their colleagues on the quantification of system redundancy of typical highway bridges and reassess previously made proposals for including system redundancy and robustness during the structural design and safety evaluation of bridge superstructure and substructure systems.
Abstract: Major advances have been recently achieved in developing methodologies for the structural analysis of cascading failures and in understanding the behaviour of different types of systems under suddenly applied extreme loads. Yet, a main issue related to defining objective measures of redundancy and quantifying the levels of redundancy that exist in structural systems remains vastly unresolved. This paper reviews the work done by the authors and their colleagues on the quantification of system redundancy of typical highway bridges and reassesses previously made proposals for including system redundancy and robustness during the structural design and safety evaluation of bridge superstructure and substructure systems. These proposals, which are based on system reliability principles, consider structural system safety, system redundancy and system robustness in comparison to member safety, and account for the uncertainties associated with determining member and system strengths as well as future loads in a co...
88 citations
TL;DR: In this article, the implementation of IDA studies in 3D structures is examined, where a two-component seismic excitation is applied, and a new procedure for performing MIDA is proposed.
Abstract: Performance-based earthquake engineering (PBEE) is the current trend in designing earthquake-resistant structures. The implementation of the PBEE framework requires the assessment of the structural capacity in multiple earthquake hazard levels. Incremental dynamic analysis (IDA) is considered to be one of the most efficient computational tools for estimating structural capacity; therefore, it is often incorporated into the PBEE framework. Most real world reinforced concrete (RC) buildings can only be represented accurately with three-dimensional (3D) models; hence, a multicomponent incremental dynamic analysis (MIDA) is required in order to carry out an IDA-based PBEE framework. In this work, the implementation of IDA studies in 3D structures is examined, where a two-component seismic excitation is applied, and a new procedure for performing MIDA is proposed. According to the proposed procedure, the MIDA is performed over a sample of record-incident angle pairs that are generated using Latin hypercube sam...
76 citations
TL;DR: In this paper, four different modeling methods are adopted to represent abutments and foundations of a bridge configuration in central and eastern USA, and fragility curves of the components and bridge system are derived.
Abstract: Seismic fragility relationships, including the soil–structure interaction (SSI) of a common bridge configuration in central and eastern USA, are derived in this study. Four different modelling methods are adopted to represent abutments and foundations of the bridge, namely, (a) fixed abutments and foundations, (b) lumped springs developed from conventional pile analysis of piles at abutments and foundations, (c) lumped springs developed from three-dimensional finite element (3D FE) analysis of abutments and foundations and (d) 3D FE models. Seismic demand on the bridge components is estimated from inelastic response history analysis of the SSI systems. Finally, fragility curves of the components and bridge system are derived. The four different SSI approaches result in different seismic fragility. The implication of this work is that careful consideration is necessary when selecting an analytical representation of a soil and foundation system to obtain reliable earthquake impact assessment. In addition, i...
70 citations
TL;DR: In this article, the authors developed a methodology developed by the authors and their co-workers for estimating direct losses from earthquakes in reinforced concrete (R/C) buildings are presented; they concern the derivation of capacity curves and vulnerability curves in terms of peak ground acceleration (PGA), as well as spectral displacement, for all types of R/C buildings that are common in Greece.
Abstract: The latest developments of a methodology developed by the authors and their co-workers for estimating direct losses from earthquakes in reinforced concrete (R/C) buildings are presented; they concern the derivation of capacity curves and vulnerability (fragility) curves in terms of peak ground acceleration (PGA), as well as spectral displacement, for all types of R/C buildings that are common in Greece. The vulnerability assessment methodology is based on the hybrid approach, which combines statistical data with appropriately processed results from nonlinear dynamic or static analyses that permit interpolation and (under certain conditions) extrapolation of statistical data to PGAs and/or spectral displacements for which no data is available. A detailed discussion of the limitations of the hybrid approach is provided, along with a proposal for improving the quality of results by applying a weighting technique to both the analytical and the statistical input data.
68 citations
TL;DR: In this article, the authors investigate the time-variant redundancy of structural systems and find that the structural redundancy is influenced by several factors, such as the material type, the resistance correlation structure and deterioration rate and the rate of increase in applied loads.
Abstract: Structural redundancy is expected to change over time due to time-variant loading and damage under uncertainties. The objective of this paper is to investigate the time-variant redundancy of structural systems. Analyses of structural reliability and redundancy affected by deterioration in structural resistance and increase in applied loads are conducted by using numerical examples. It is shown that the structural system redundancy is influenced by several factors, such as the material type, the resistance correlation structure and deterioration rate and the rate of increase in applied loads. The results show the importance of including the time factor in the quantification of redundancy. Such results are useful for identifying the best measures to take in order to maintain a satisfactory level of redundancy throughout the life of structural systems and to incorporate the time-variant redundancy in a lifetime-oriented multi-objective optimisation framework of risk-based management of structural systems.
65 citations
TL;DR: The performance of the bridge is quantified by incorporating prior knowledge and information obtained from structural health monitoring using Bayesian updating concepts, and this performance is predicted in the future using extreme value statistics.
Abstract: 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.
TL;DR: In this article, two non-repetitive distribution methods are proposed and compared with some often adopted methods and a repetitive simplified sequential search algorithm for estimating damping coefficients of viscous dampers corresponding to a desired added damping ratio.
Abstract: A simple and convenient method often adopted by practising engineers designing supplemental viscous dampers to a building is to calculate damping coefficients of viscous dampers corresponding to a desired added damping ratio. To facilitate the design, various methods for distributing damping coefficients along the height of the building are compared in the study. In the article, two non-repetitive distribution methods are proposed and compared with some often adopted methods and a repetitive simplified sequential search algorithm. Numerical studies of three planar frames in which two are vertically irregular have indicated that all distribution methods may result in similar seismic responses if added damping ratio are the same. Nevertheless, compromising among a few design factors such as the total added damping coefficient, maximum damper force at one storey, total added damper force, control of storey drift and total computational efforts, one of the two proposed methods distributing the damping coeffic...
TL;DR: In this paper, satellite radar data are analyzed to control the deformation of the buildings of Murcia City (SE Spain) affected by subsidence, which occurs as a result of groundwater overexploitation in drought periods, and special attention is paid to the most recent drought which occurred between 2005 and 2008.
Abstract: In this article, satellite radar data are analysed to control the deformation of the buildings of Murcia City (SE Spain) affected by subsidence. This phenomenon has occurred as a result of groundwater overexploitation in drought periods, and special attention is paid to the most recent drought which occurred between 2005 and 2008. In the first part of this work, the study area is presented followed by a description of the characteristics and effects of subsidence on the buildings of the urban area. Persistent scatterer interferometry is used to process a satellite base radar dataset measuring the temporal and the spatial evolution of subsidence. These results are analysed with respect to several factors that control subsidence mechanisms: water table decrease, thickness of the compressible layer and the type of foundation of the buildings. To validate these results, a detailed structural damage analysis of several buildings is presented. According to the results presented in this work, it may be concluded...
TL;DR: In this paper, the structural robustness of reinforced concrete (RC) foot bridges under corrosion is defined and a new robustness definition and a framework is proposed for its analysis, based on the structural performance lost after damage occurrence.
Abstract: The aim of this work is to provide new contributions in order to define more accurately the structural robustness concept, particularly when applied to corroded reinforced concrete (RC) structures. To fulfil such a task, several robustness indicators are analysed and discussed with special emphasis on structural-performance-based measures. A new robustness definition and a framework are then proposed for its analysis, based on the structural performance lost after damage occurrence. The competence of the proposed methodology is then tested comparing the robustness of two RC foot bridges under corrosion. The damage considered is the longitudinal reinforcement corrosion level, and load carrying capacity is the structural performance evaluated. In order to analyse corrosion effects, a finite element (FE) based on a two-step analysis is adopted. In the first step, a cross-section analysis is performed to capture phenomenons such as expansion of the reinforcement due to the corrosion products accumulation; dam...
TL;DR: In this paper, the main sleeper design parameters including rail seat loads, sleeper-ballast contact pressures and sleeper bending capacities are considered in the investigation of steel, timber and concrete sleepers.
Abstract: In this research, the mechanical behaviour of steel, timber and concrete sleepers is investigated and compared by conducting several laboratory and field tests. The main sleeper design parameters including rail seat loads, sleeper-ballast contact pressures and sleeper bending capacities are considered in this investigation. New formulae for the calculation of sleeper design parameters are developed for steel, timber and concrete sleepers. Results indicate that the new formulae can improve the accuracy of current practices in the analysis and design of sleepers. Comparisons of the mechanical properties of steel, timber and concrete sleepers indicate the optimum sleeper type based on railway structural and operational conditions.
TL;DR: In this paper, 20 wireless sensing nodes are connected to a ship-wide fiber-optic data network to serve as a hybrid wireless hull monitoring system on a high-speed littoral combat vessel (FSF-1 Sea Fighter).
Abstract: There is increasing interest by the naval engineering community in permanent monitoring systems that can monitor the structural behaviour of ships during their operation at sea. This study seeks to reduce the cost and installation complexity of hull monitoring systems by introducing wireless sensors into their architectural designs. Wireless sensor networks also provide other advantages over their cable-based counterparts such as adaptability, redundancy, and weight savings. While wireless sensors can enhance functionality and reduce cost, the compartmentalised layout of most ships requires some wired networking to communicate data globally throughout the ship. In this study, 20 wireless sensing nodes are connected to a ship-wide fibre-optic data network to serve as a hybrid wireless hull monitoring system on a high-speed littoral combat vessel (FSF-1 Sea Fighter). The wireless hull monitoring system is used to collect acceleration and strain data during unattended operation during a one-month period at s...
TL;DR: In this paper, the safety analyses of three infrastructures that have been shaken by an earthquake are described, modelled and computed: the electric power, water and road systems.
Abstract: Realistic assessment of network structural safety requires modelling of a reasonably large part of the network itself. Although this statement may appear too demanding, both for modelling and computing reasons, there are clear motivations and technological possibilities to do complex network analyses. In this paper, the safety analyses of three infrastructures that have been shaken by an earthquake are described, modelled and computed: the electric power, water and road systems. For each network, results extracted from real networks, some of which have been studied in the past by the authors, are presented and discussed. No inter-network analysis is carried out, although it is recognised that this would be the most complete approach. The common parts in the procedure to model and analyse each network, via Monte Carlo simulations, are detailed at the beginning of the paper, thus showing the many common points that show up in any network analysis.
TL;DR: In this article, a methodology for prioritising between different maintenance actions in railway infrastructure is presented, and the consistency of the prioritisation and the feasibility of the applied methodology are investigated.
Abstract: A methodology for prioritising between different maintenance actions in the railway infrastructure is presented. The consistency of the prioritisation and the feasibility of the applied methodology are investigated. Criteria describing the diverse effects of maintenance are developed and presented to track managers, together with a set of maintenance actions that are specific for each track manager. Then, the analytical hierarchy process (AHP) is used to obtain preferences for the criteria and for the different actions. The track managers roughly agree on the prioritisation of criteria. However, the discrepancies between the results of the two ways employed to elicit the preferences for the actions are rather large. The track managers consider it easy to understand the rationale of the AHP and to enter their preferences. It is proposed that preferences are recorded as they are in this paper, in order to document the rationale of the decisions and to facilitate mutual learning among decision-makers and ove...
TL;DR: In this article, the authors describe the development of computational tools for modal identification and long term dynamic monitoring in LabVIEW environment, which mainly consist of two individual toolkits for structural modality identification (SMI) and continuous monitoring (CSMI).
Abstract: This paper describes the development of computational tools for modal identification and long term dynamic monitoring in LabVIEW environment. These tools mainly consist of two individual toolkits for structural modal identification (SMI) and continuous monitoring (CSMI), respectively. The SMI toolkit implements the frequency domain Peak-Picking (PP) and Enhanced Frequency Domain Decomposition (EFDD) method, as well as the time domain Stochastic Subspace Identification (SSI) techniques. Based on this toolkit, the user can easily develop the whole process of structural modal identification by simply pushing buttons. The CSMI toolkit was conceived for continuous dynamic monitoring excluding manual interaction. It automatically searches the latest output measurements, detects maximum vibration amplitudes and makes statistical treatment of acceleration time series, generates waterfall plots for depicting the frequency component distribution and identifies modal parameters based on automated EFDD technique. The...
TL;DR: The test results demonstrate that in-network data reduction is a very promising but challenging approach, since it has to be implemented with very limited computational and memory resources.
Abstract: Wireless sensor networks (WSNs) are a promising technology that could induce a significant innovation in the field of structural monitoring. The main advantages of WSNs are fast deployment, little interference and self-organisation. However, since WSN are battery powered, the power management of the sensor nodes significantly influences the operation method and the overall data management process. Since data communication is the most energy-consuming task, a significant data reduction has to be attained in the sensor nodes to achieve system lifetimes that are useful for real life applications. This paper discusses several basic aspects of data processing and data management for long-term monitoring with WSNs. It presents a specific monitoring system and illustrates a long-term field test performed with this system on a bridge. The test results demonstrate that in-network data reduction is a very promising but challenging approach, since it has to be implemented with very limited computational and memory r...
TL;DR: In this paper, the authors investigated the sensitivity of seismic fragility estimates for bridge components to variation in structural and liquefiable soil modelling parameters, including undrained shear strength of soil, structural damping ratio, soil shear modulus, gap between deck and abutment, ultimate capacity of soil and fixed and expansion bearing coefficients of friction.
Abstract: This study investigates the sensitivity of seismic fragility estimates for bridge components to variation in structural and liquefiable soil modelling parameters. A rigorous sensitivity analysis is conducted to evaluate the relative importance of 13 random variables that reflect uncertainty in the seismic performance assessment of bridges in regions with liquefiable soils. The results indicate that the fixed and expansion bearings and bent piles tend to be sensitive to the greatest number of modelling parameters for the case study system, while the abutments are less sensitive. The most significant modelling parameters affecting the seismic fragility include such parameters as undrained shear strength of soil, structural damping ratio, soil shear modulus, gap between deck and abutment, ultimate capacity of soil and fixed and expansion bearing coefficients of friction. The 5% and 95% confidence intervals reveal wide bounds on the seismic fragility curves, particularly for more vulnerable bridge components ...
TL;DR: In this paper, the Monte Carlo simulation (MCS) technique is considered to be the most consistent reliability analysis method, with no limitations on its applicability range, and the authors present the efficiency of the MCS-based numerical approach versus the common linear approach.
Abstract: Typically, seismic analysis of large-scale geostructures, such as embankments, is performed by means of deterministic pseudostatic slope stability methods, where a safety factor based approach is adopted. However, probabilistic seismic fragility analysis can be a more efficient and realistic approach for interpreting more accurately the seismic performance and the vulnerability assessment of an earth structure. There are two major approaches for performing vulnerability analysis: either approximately assuming that the demand values follow a lognormal distribution or numerically most frequently using the Monte Carlo simulation (MCS) method, where the probability of exceedance for every limit state is obtained by performing MCS analyses for various intensity levels. The MCS technique is considered to be the most consistent reliability analysis method, with no limitations on its applicability range. The objective of this work is to present the efficiency of the MCS-based numerical approach versus the commonl...
TL;DR: In this article, the dynamic interactions between high-speed trains and reinforced concrete viaducts using field measurements and numerical simulations are investigated, and a new numerical vibration prediction scheme for a train-bridge system is developed.
Abstract: This study investigates the dynamic interactions between high-speed trains and reinforced concrete viaducts using field measurements and numerical simulations. The dynamic responses of a 40 year old viaduct under high-speed train passage are measured. Using general finite-element method software, a new numerical vibration prediction scheme for a train–bridge system is developed. Following the Newmark scheme, a decoupling algorithm is derived through the contact force between a train and viaduct. Track irregularity is also taken into account. The proposed numerical scheme is verified through a comparison between calculated responses and in situ measured responses. This approach is expected to provide not only an accurate simulation tool for train-induced vibration, but also instructive information for the retrofit of railway structures, especially at higher speeds.
TL;DR: In this article, a multi-scale model of Runyang cable-stayed bridge is developed, which is essentially a multiscale combination of a finite element model for modal analysis of the entire bridge structure and FE sub-models for local stress analysis of selected locations with respect to the substructuring method.
Abstract: Accurate evaluation of the effect of possible damage in critical components on the dynamic characteristics of a structure is of critical importance in developing a robust structural damage identification scheme for a long-span cable-stayed bridge. The strategies of finite element (FE) modelling of a long-span cable-stayed bridge for multi-scale numerical analysis are first investigated. A multi-scale model of the Runyang cable-stayed bridge is then developed, which is essentially a multi-scale combination of a FE model for modal analysis of the entire bridge structure and FE sub-models for local stress analysis of the selected locations with respect to the substructuring method. The developed three-dimensional global-scale and local-scale FE models of Runyang cable-stayed bridge achieve a good correlation with the measured dynamic properties identified from field ambient vibration tests and stress distributions of a steel box girder measured from vehicle loading tests, on the basis of which the effectiven...
TL;DR: In this article, the authors evaluated the performance of eight flexible pavement rehabilitation treatments and found that 5-inch treatments were on average more effective in terms of the following measures: 47% (estimated service life) and 35% (ABP) depending on the level of surface preparation, mix type and initial pavement condition.
Abstract: Engineers continually seek effective techniques for preserving highway infrastructure. Using data from the specific pavement study#5 of the long-term pavement performance (LTPP) programme's western region, this article evaluated the performance of eight flexible pavement rehabilitation treatments. Aggregate and disaggregate post-treatment performance models were developed for each treatment. Effectiveness was measured in the short term (roughness reduction) and long term (estimated treatment service life and area bounded by the performance curve (ABP)). The results showed that compared to 2-inch treatments, 5-inch treatments were on average more effective in terms of the following measures: 47% (estimated service life) and 35% (ABP) depending on the level of surface preparation, mix type and initial pavement condition. Also, relative to minimal surface preparation, intensive surface preparation generally yielded greater effectiveness: 25% (estimated service life) and 49% (ABP) depending on added thickness...
TL;DR: In this article, the authors used receiver operating characteristic (ROC) curves to find out the efficiency of an NDT technique in a probabilistic way for various damage definitions and environmental conditions.
Abstract: The localisation and calibration of damage in a structure are often difficult, time consuming, subjective and error prone. The importance of a simple, fast and relatively inexpensive non-destructive technique (NDT) with reliable measurements is thus greatly felt. The usefulness and the efficiency of any such technique are often affected by environmental conditions. The definition of damage and the subsequent interpretation of the possible consequences due to the damage introduce subjectivity into an NDT technique and affect its performance. It is of great importance in terms of practical application to find out the efficiency of an NDT technique in a probabilistic way for various damage definitions and environmental conditions through the use of receiver operating characteristic (ROC) curves. Such variations of performance of an NDT tool can be predicted through simulation processes, and the test conditions conducive to good detections can be isolated and ranked according to their relative efficiency. Thi...
TL;DR: The ground penetrating radar (GPR) has been used for some decades in the non-destructive inspection and diagnosis of concrete bridges as mentioned in this paper, which is useful to find general information about the true position of reinforcement and tendon ducts, and check the quality of the construction and materials.
Abstract: Non-destructive tests (NDT) are an essential tool used in special inspections to gather detailed information about the condition of a bridge. The inspection of bridge decks is a critical task, and, currently, can be successfully carried out using a wide range of NDT techniques. Nevertheless, some of these techniques are excessively expensive and time consuming. One of these techniques, the ground penetrating radar (GPR), has been used for some decades in the non-destructive inspection and diagnosis of concrete bridges. GPR is useful to find general information about the true position of reinforcement and tendon ducts, and check the quality of the construction and materials. A significant number of reinforced and prestressed concrete bridges are deteriorating at a rapid rate and need to be repaired and strengthened. During these rehabilitation processes, designers are often faced with a lack of original design plans and unawareness of the real position of reinforcement and tendon ducts. In this paper, thre...
TL;DR: In this article, the authors used the ACI-AASHTO approach, strut and tie method, modified compression field theory, and Response 2000™ to predict the shear strength of corrosion damaged and undamaged test beams.
Abstract: Corrosion of embedded carbon steel is a leading factor in deterioration of ageing conventional reinforced concrete structures. Methods to accurately predict remaining capacity of corrosion damaged elements, especially shear capacity, are lacking. In this paper, ACI-AASHTO approach, strut and tie method, modified compression field theory, and Response 2000™ were used to predict the shear strength of corrosion damaged and undamaged test beams. The methods were modified to account for the corrosion induced damage to both the concrete section and stirrups. Each of the methods considered, with the proposed modifications, reasonably estimated the remaining shear capacity of large-size laboratory specimens subjected to accelerated corrosion of embedded stirrups.
TL;DR: In this paper, the authors present an approach for fatigue reliability evaluation of ship structures based on the estimated lifetime sea loads for high-speed ship structures with the aim of assessing fatigue performance and predicting service life from available data.
Abstract: This article focuses on estimating probabilistic lifetime sea loads for high-speed ship structures with the aim of assessing fatigue performance and predicting service life from available data. Performance assessment and service life prediction for naval ship structures are extremely important issues. In particular, understanding the effect of sea loading on naval high-speed vessels is still a challenge. Potential lifetime load effects including low frequency wave-induced and high frequency slam-induced whipping loadings are investigated in this article by using a probabilistic approach. Clearly, integration of probabilistic sea loads into structural reliability assessment and service life prediction will provide a more reliable estimation of the long-term structural performance. Accordingly, this article presents an approach for fatigue reliability evaluation of ship structures based on the estimated lifetime sea loads. Loading information associated with sea states, ship speeds and relative wave heading...
TL;DR: This paper presents practical software tools used for service life prediction, concrete cover evaluation and assessment of relevant reliability levels and a partial verification using test results is presented.
Abstract: This paper deals with durability design and comments on the assessment of reinforced concrete (RC) structures in relation to existing codes. Enhancement is provided by advanced approaches incorporating probabilistic simulations, mathematical models of the carbonation process in concretes made from CEM I through to CEM V, and the reliability issue. This paper presents practical software tools used for service life prediction, concrete cover evaluation and assessment of relevant reliability levels. A partial verification using test results is also presented.