Machine learning is one of the key pillars of industry 4.0 that has enabled rapid technological advancement through establishing complex connections among heterogeneous and highly complex engineering ...data automatically. Once the machine learning model is trained appropriately, it becomes able to effectively predict and make decisions. The technology is rapidly evolving and has found numerous applications in various branches of engineering due to its preponderance. This study is focused on exploring the recent advances of machine learning and its applications in reinforced concrete bridges. It covers a range of different machine learning techniques exploited in structural design, construction quality management, bridge engineering, and the inspection of reinforced concrete bridges. This review demonstrated that machine learning algorithms have established new research directions in bridge engineering, in particular for applications such as the form-finding of innovative long-span structures, structural reinforcement, and structural optimization.
A comprehensive probabilistic assessment framework and methodology for evaluating the seismic resilience of in-service bridge structures have been developed, utilizing a combination of the maximum ...drift ratio (MDR) and residual drift ratio (RDR) indicators. This approach effectively addresses non-uniform corrosion on structural facades and the consequential shift in failure modes due to corrosive damage. To illustrate its applicability, a seismic resilience analysis was conducted over the life-cycle of a RC bridge. Based on the time-varying seismic fragility analysis, a further assessment was conducted, which encompassed post-earthquake functional loss, the recovery process, and seismic resilience. The research findings emphasize that corrosive damage significantly diminishes the seismic performance of bridge piers. As the service life progresses, both MDR and RDR gradually increase, demonstrating a positive correlation. Damage probabilities and functional losses obtained through the MDR-RDR indicators exceed those derived from single indicators. Additionally, the functional recovery time based on MDR-RDR indicators consistently exhibits an escalation. As service life and PGA levels increase, the seismic resilience assessed using various indicators displays a declining trend, with a particularly notable reduction rate observed for the MDR-RDR indicator. The results of this study underscore the importance of concurrently considering aging and combined indicators when assessing the seismic resilience of bridge structures throughout their service life. These results provide novel insights for the comprehensive assessment of seismic resilience in structures during service period.
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•A framework and methodology for evaluating the whole-life seismic resilience of in-service bridge structures.•An integrated approach to consider of the uneven corrosion and the shift in failure modes due to corrosion damage.•A case study on the analysis of time-varying seismic fragility and seismic resilience of a bridge structure.
The assessment of existing reinforced concrete structures, especially bridges and viaducts, nowadays is one of the most relevant aspects for engineers. In fact, due to the old age of a large part of ...the infrastructure assets and the deteriorating conditions affecting the structural elements, their safety with respect to the ultimate limit states may be compromised. In this perspective, the assessment by means of global safety formats employing non-linear finite element analyses can be an extremely useful tool. In this context, the study proposes to relate the safety level to the damage through 3D global non-linear numerical analyses. Specifically, the assessment of an existing prestressed reinforced concrete bridge deck is carried out by means of the global safety format denoted as “Estimation of Coefficient of Variation” (ECOV) assuming different damage scenarios. In fact, the safety of the structure is initially assessed with respect to the ultimate limit state in its undamaged condition. Subsequently, different damage scenarios, derived from the inspections, are numerically studied. For each damage scenario, the safety of the deck is evaluated with respect to the ultimate limit state relating the safety loss to the damage level. Finally, damage thresholds for this type of structure are defined on specific static parameters.
•Safety of an existing prestressed reinforced concrete bridge deck is assessed.•3D NLFE models are defined within the global safety format ECOV.•A visco-elastic analysis is performed to reproduce the time-dependent effects.•Different damage scenarios are simulated by varying degradation characteristics.•Specific damage thresholds are numerically proposed and related to damage level.
•Impact of ground motion duration on the seismic behavior of RC bridges is quantified.•Role of low-cycle fatigue damage of reinforcing bars in the impact of duration is identified.•An advanced ...material-level damage index is used to account for both the strain and fatigue damage.•Stain damage controls under short-duration motions, while fatigue damage may control under long-duration motions.•Fatigue damage is more prominent under more severe damage states of bridges against long-duration motions.
This paper assesses the influence of ground motion duration on seismic behavior of reinforced concrete (RC) bridge piers using spectrally equivalent short- and long-duration ground motions. Special attention is paid to the role of low-cycle fatigue damage of reinforcing bars. To this end, an experimentally validated nonlinear fiber-based beam-column element considering buckling and low-cycle fatigue of longitudinal bars is adopted for nonlinear dynamic analyses and fragility modeling. An advanced material level damage index is used to account for both the maximum response (strain damage) and cumulative damage (low-cycle fatigue damage of longitudinal bars). The dynamic analysis results indicate that the strain damage is the major failure mechanism for RC bridge piers under short-duration ground motions. Under long-duration ground motions, by contrast, the strain damage is prominent at the early excitation stage, while the low-cycle fatigue damage may dominate the late excitation stage. In particular, the role of low-cycle fatigue is more prominent for RC bridges against long-duration ground motions with significant durations beyond 50 s and peak ground velocities over 30 cm/s. The fragility analysis demonstrates that, ignoring the low-cycle fatigue damage of longitudinal bars will obviously underestimate the seismic fragility of RC bridge piers under long-duration ground motion, and the influences is more significant at more severe damage states. Therefore, the low-cycle fatigue damage of reinforcing bars is one of the main failure modes of RC bridge piers under long-duration ground motion, and should be considered in the seismic design,
•Develops stochastic framework for modeling deterioration processes and their interaction.•Proposes general state dependent stochastic models for deterioration.•Proposes Bayesian approach for ...calibration of deterioration models.
For performance analysis of deteriorating engineering systems, it is critical to model and incorporate the various deterioration processes and associated uncertainties. This paper proposes state-dependent stochastic models (SDSMs) for modeling the impact of deterioration on the performance of engineering systems. Within the stochastic framework, the change of the system state variables due to different deterioration processes and their interaction is modeled explicitly. As a candidate model to be used in the framework, a new general age and state dependent stochastic model for gradual deterioration is proposed, and its calibration based on data is also discussed. Once the time-variant system state variables are modeled, proper capacity and demand models that take them as inputs can be adopted to fully capture the impact of deterioration processes on the capacity, demand, and other system performances. The proposed framework is first demonstrated through a simple example, and then is used to model the deterioration of an example reinforced concrete (RC) bridge considering deterioration caused by both corrosion and earthquake including their interaction. The results show the importance of modeling the interaction between different deterioration processes, and also verify the advantages of the proposed framework.
•A multi-platform simulation method was proposed to assess the performance of reinforced concrete structures under impact loading;•Integration of the VecTor2 program with LS-DYNA to take advantage of ...the Modified Compression Field Theory for impact-induced shear damage;•Development of a coupling method to satisfy the compatibility at the interface between the LS-DYNA model and the VecTor2 model;•Verification of the proposed method through examples for general dynamic analysis as well as vehicle/ship head-on collisions;•The advantages of the multi-platform method over the conventional standalone simulation method as demonstrated through a vehicle-bridge collision problem.
This study presents a multi-platform simulation method for performance assessment of reinforced concrete (RC) structures subjected to impact loading. The method is demonstrated through the integration of two finite element analysis packages, LS-DYNA and VecTor2, to take advantage of the explicit integration scheme and various contact types in LS-DYNA for impact analysis and the Modified Compression Field Theory (MCFT) in VecTor2 for reliable modelling of concrete structures, especially for shear-related failure. The communication between the two programs is enabled through a standardized communication protocol which allows data exchange during the simulation in a seamless manner. When applying this method to vehicle/ship collision analysis, one major challenge is the modelling of the impact interface between the three-dimensional LS-DYNA model and the two-dimensional VecTor2 model. Therefore, a coupling method for models with different dimensions is proposed and also justified through a few verification examples. The method is also applied to a vehicle-bridge head-on collision problem and it is found that the conventional modelling method based on a single LS-DYNA model could overestimate the crashworthiness of the RC structures.
•An improved reinforced concrete steel bar deterioration model that incorporates pitting corrosion is proposed.•Change in after-cracking corrosion rate is considered to assess the time-dependent ...seismic fragility of RC bridges.•Differences in the results when reinforcing steel is subjected to general and pitting corrosion are investigated.•Seismic fragility of deteriorating RC bridges in marine environment is evaluated.
This paper presents an improved reinforced concrete steel bar deterioration model that incorporates pitting corrosion and considers the change in after-cracking corrosion rate to assess the time-dependent seismic fragility of RC bridge substructures in marine environments. The proposed deterioration model is applicable for both existing and new RC bridge substructures and could be employed for life-cycle analysis of RC bridge substructures in marine environments. In this paper, the model is implemented to conduct a probabilistic seismic fragility analysis of a three-span continuous box girder bridge accounting for uncertainties in establishing bridge geometry, material properties, ground motion and corrosion parameters. Differences in the results obtained when reinforcing steel is subjected to general and pitting corrosion are investigated. The results show that the effect of chloride-induced corrosion cannot be neglected when performing the seismic fragility analysis of RC bridge substructures in marine environments. Additionally, the calculated time-dependent fragility curves indicate that there is a nonlinear accelerated growth of RC column vulnerability along the service life of highway bridges, especially after twenty-five years of exposure to chlorides.
•Shear modulus and friction coefficient for bearings in ageing bridges are difficult to attain.•An existing bridge is assessed by varying un-reinforced thin elastomeric bearing properties.•Seismic ...risk can be significantly sensitive to friction coefficient but not rubber shear modulus.•Simplified structural modelling almost always yields conservative results regarding safety but not losses.•More efforts are required to define the friction coefficient accurately as it significantly influences risk.
A growing challenge in the seismic risk assessment of ageing existing bridge structures is the lack of knowledge of the key features of the structural components. In fact, the mechanical properties could change over time and the recommendations in the literature could be considerably different thus adopted modelling parameters can significantly alter the seismic response and risk estimates,e.g., expected annual losses (EAL) or mean annual frequency of collapse (MAFC). It is therefore crucial to understand the role of critical properties of structural components on seismic risk metrics before allocating further resources to estimate them more accurately.With the above in mind, this study focuses on analysing the importance of the frequently unknown properties of bridge bearings featuring un-reinforced thin elastomeric pads, typically used in bridges built in the ‘60 s and ‘70 s in Italy. For this purpose, a real case study bridge is selected and Latin Hypercube Sampling is performed to generate a large set of bearing parameters, namely the shear modulus and friction coefficient between rubber and concrete surfaces. Component-level seismic loss estimation of the bridge is performed for each bearing properties realisation, considering both the presence and absence of non-sacrificial shear keys at the cap beams. The EAL and MAFC results are scrutinised to analyse the impact of the variation in the bearing properties on such risk metrics. The main observations indicate that the influence of the shear modulus of rubber on these quantities is low, whereas the friction coefficient between concrete and rubber can lead to more impactful changes.
•Predicting the residual life of a RC bridge based on steel corrosion and maintenance intervention cycle period.•The relationship between steel corrosion and crack propagation is established.•The ...reliability index of the RC bridge is determined by maintenance intervention cycle period.•Under coastal environmental conditions, the maintenance intervention cycle period needs to be significantly shortened.
The development of effective life cycle management strategies for transport infrastructure assets is of importance for meeting the defined public policies and levels of service. In the last decades, much progress has been made in assessing the life-cycle performance of bridges using reliability-based approaches. However, the goal of developing a comprehensive life-cycle performance assessment framework for bridges has not been fully achieved. This is due to the uncertainties surrounding model parameters as well as the correlation between these parameters (e.g. the complex correlation between the reinforcement corrosion and the concrete cracking). It becomes more challenging due to the limited access to bridge inspection data by bridge research communities resulting from confidentiality issues. Using a typical highway concrete bridge as a case study, the present study systematically investigated the impact of concrete crack induced reinforcement corrosion on the serviceability of concrete bridges by developing an engineering reliability-based approach involving an auto-regressive crack propagation model and a steel corrosion prediction model. The model parameters were calibrated using the eight-year inspection data of an operating bridge. The influence of different external environments in the reinforcement corrosion, ultimately the residual life of the bridges, was also investigated through conducting a series of parametric studies. Based on the collected bridge inspection data, the model results predict that, although the surface crack of a RC bridge is repairable through periodic maintenance, the corrosion of the steel bars in the bridge still continues over time with a corrosion rate which depends on different maintenance intervention cycle periods (Tcycle). For example, reducing Tcycle from 12 years to 4 years could potentially prolong the service life of the bridge by around 15 years. The developed model could assist bridge managers to estimate the optimal Tcycle to prolong the service life of bridges.
This paper describes a probabilistic approach to determine optimal monitoring strategies for post-earthquake damage estimation of aging reinforced concrete bridges. Various monitoring strategies are ...considered, including different inspection parameters, techniques and inspection intervals. Parameters include fundamental mode period, crack width, and residual displacement. Incremental damage is estimated by comparing the post-event measurement of a particular parameter of the structure with the most recent information available. Monte Carlo simulation is used to generate sequences of hazards, including earthquakes, corrosion and scour, and their joint (interacting) effects on bridges. Applications of the framework are described for a typical multiple-column pier and simply-supported deck concrete bridge, as is common in the Central and Southeastern United States. The objective function considered for risk-informed post-earthquake monitoring of bridges can vary depending on the actual condition of the bridge and its safety requirements. Our methodology prioritizes maximizing damage prediction accuracy, which suggests different optimal monitoring planning throughout the life of the bridge.
•Methodology for risk-based post-earthquake inspection of reinforced concrete bridges.•The interaction of multiple hazards was included with seismic hazard being dominant.•The optimal monitoring strategy changes with the age of the bridge.•Combinin sensing modalities offers a better performance than a single modality.•Intermittent and periodic monitoring strategies were investigated and compared.
