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Ground penetrating radar (GPR) is a widely utilized nondestructive testing technique for the detection and assessment of internal corrosion in concrete bridge decks. However, abnormal data generated during the practical application of this technology can reduce the accuracy of concrete bridge deck corrosion assessment. Aiming at this problem, this paper analyzes some common abnormal data from actual bridges GPR data and proposes corresponding automatic algorithms for anomaly correction to enhance assessment accuracy. The automatic algorithm focuses on two main aspects: correcting anomalies in direct coupling wave amplitudes based on data statistics and mitigating the impact of abnormal data due to incorrectly picked rebar on depth correction using density clustering. The specific process of the automatic method can be divided into four steps. First, automatic rebar picking is performed based on the preprocessed GPR data. Next, data statistics analysis is implemented on the extracted rebar data to identify and correct abnormal amplitude data. Then, the true rebar data are identified for depth correction based on density clustering. Finally, the bridge deck corrosion map is generated based on the corrected rebar reflection amplitudes and rebar positions. The feasibility of this method was verified through a case study with GPR data from two in-service bridges. The results show that this method can effectively and automatically identify and correct abnormal data. Moreover, the bridge deck corrosion map obtained by the proposed method is also more accurate. It can be concluded that the proposed algorithms can be used in bridge deck corrosion detection and assessment with GPR. Practical Applications: Ground penetrating radar (GPR) is a widely utilized nondestructive testing technique for concrete bridge deck corrosion detection and assessment. However, abnormal data generated during the practical application of this technology can reduce the accuracy of concrete bridge deck corrosion assessment. Aiming at this problem, this paper proposes a set of automatic data processing procedures for anomaly correction to improve the corrosion assessment accuracy. The feasibility of the proposed algorithms was validated through a case study with GPR data from two in-service bridges. The results show that these algorithms can effectively automatically identify and correct abnormal data. Moreover, the bridge deck corrosion map obtained by these algorithms is also more accurate. It can be concluded that the proposed algorithms can be used in bridge deck corrosion detection and assessment with GPR. [ABSTRACT FROM AUTHOR]

Abstract In the inspection and diagnosis of concrete construction, crack detection is highly recommended in the earliest phases to prevent any potential risks later. However, the flaws in concrete surfaces cannot be reliably and effectively identified using traditional crack detection techniques. The suggested algorithm is a supportive tool for agents or authorities to use in crack detection mechanisms to monitor and assess the current condition of buildings or bridges. The researchers aim to establish an intelligent model for automatic crack detection on different concrete surfaces based on image processing technology. Three different concrete surfaces—bridge decks, walls, and concrete cubes—are used to test the model. A subset of the public dataset of bridge decks and walls from SDNET (2018) and 150*150*150 mm of concrete cubes taken from the material laboratory of the faculty of engineering at Ain Shams University are applied to the model. The model F1-score measures are 98.87%, 97.43%, and 74.11% for detecting cracks in bridges, walls, and concrete cubes, respectively. The validation of the applicability of the suggested novel approach is based on a comparison with recent methods for crack recognition. The contribution of this study is that it could be applied to detect cracks efficiently on three different types of concrete surfaces, including uneven concrete surfaces, random noise, voids, dents, colour changes, and stain marks. The proposed method is transparent in its workflow and has a lower computational cost compared with deep learning frameworks. Thus, the outcomes of this model demonstrate its effectiveness in concrete defect field investigation.

Concrete bridge decks are critical transportation infrastructure components where deterioration can compromise structural integrity and public safety. This study develops machine learning (ML) models using the National Bridge Inventory (NBI) to classify deck conditions and predict deterioration trajectories. Models were tested and trained on inspection records from over 28,786 bridges in Michigan over 23 years, from 1992 to 2015. Eleven approaches were evaluated after hyperparameter optimization, based on 10-fold cross-validation, including logistic regression, gradient boosting, AdaBoost, random forest, extra trees, K-nearest neighbors, naive Bayes, decision tree, LightGBM, CatBoost, and bagging. Model effectiveness was assessed using accuracy, recall, F1-score, and area under the curve. Results indicate the optimized CatBoost classifier achieved 96.66% testing accuracy in rating deck conditions. The incorporation of hyperparameter optimization has significantly enhanced the overall predictive performance of the models, ensuring robust and reliable deterioration forecasting. The research sheds light on crucial factors such as deck age, area, and average daily traffic, contributing to a more comprehensive understanding of the factors influencing bridge deck condition ratings. These insights inform preventative maintenance planning to extend service life. This work pioneers a data-driven framework to forecast concrete deterioration, empowering officials with precise predictions to optimize infrastructure management under budget constraints. The approach provides a promising decision-support tool for sustainable infrastructure. This paper explores the use of machine learning techniques for the deterioration prediction of concrete bridge decks to estimate the remaining service life of bridges. These models will contribute to the safety, efficiency, and sustainability of bridge infrastructure by providing timely information and evidence-based decision making for bridge maintenance and management. Such prediction models have several practical applications such as (1) predicting when maintenance or repairs are likely to be needed; (2) assessing the risk of failure or deterioration of different components of a bridge; (3) effectively managing the bridge life cycle by providing insights into the aging process and helping authorities plan for rehabilitation or replacement strategies; (4) enabling ongoing monitoring of the performance of a bridge under various conditions such as heavy traffic loads, environmental factors, and seismic events; and (5) assisting in effective asset management by allowing for the prioritization of investments, the efficient allocation of budgets, and the planning for the long-term sustainability of the bridge infrastructure. [ABSTRACT FROM AUTHOR]

The detection and evaluation of internal corrosion of concrete bridge decks is of critical importance for bridge structure safety. Ground penetrating radar (GPR) is a nondestructive testing technique that has been used widely for corrosion assessment of RC bridge decks. However, the recognition accuracy of traditional automatic data processing methods for blurred hyperbolic features is insufficient, which leads to a decrease in the accuracy of bridge deck corrosion assessment. To address this problem, this paper proposes an automatic rebar picking algorithm based on gradient information and a migration method for bridge deck corrosion assessment with GPR data. This method can be divided into three steps: thresholding processing based on B-scan gradient information, a limited hyperbolic summation-based recognition (LHSR) algorithm, and rebar localization. First, the GPR B-scan is transformed into its gradient image and thresholded to enhance hyperbolic features. The LHSR algorithm then is applied to the binarized gradient B-scan to identify the hyperbolas, locate the rebar, and extract the rebar reflection amplitude. Finally, the corrosion map of the bridge deck is generated based on the rebar position and the rebar reflection amplitude after depth-correction. A case study with GPR data from two tested bridges was employed to validate the feasibility of the proposed method. The results show that the precision and recall of automatic rebar picking by this method for poor-quality GPR data were 91.27% and 93.56%, which are significantly higher than those of the traditional methods. Moreover, the accuracy of the bridge deck corrosion map obtained by the proposed method also is significantly better than that of the traditional methods. It can be concluded that the proposed method can be used for rebar picking and corrosion assessment of RC bridge decks with GPR data. Ground penetrating radar is a nondestructive testing technology that has been used widely for corrosion assessment of concrete bridge decks. However, the traditional automatic processing method of GPR data has insufficient recognition accuracy for blurred features of rebars, resulting in a decrease in the accuracy of bridge deck corrosion assessment. To address this problem, this paper proposes an automatic method that can be used for feature identification and location of rebars. The corrosion map generated by the position and reflection amplitude of rebars could help engineers to conduct corrosion assessment and repair of concrete bridge decks. The feasibility of the proposed method was validated through a case study with GPR data form two actual bridges. Especially for poor-quality GPR data, the accuracy of rebar picking and corrosion maps of this method is significantly higher than that of traditional methods. It can be concluded that the proposed method can be used for rebar positioning and corrosion assessment of concrete bridge decks based on GPR inspection data. [ABSTRACT FROM AUTHOR]

Staged construction is often used for bridges, in which a portion of a bridge remains open to traffic while another portion is closed for construction. Although staged construction reduces delays and the need for detours, subjecting the partially constructed bridge to dead and vehicular live loading can lead to damage and subsequent deterioration, including compromised longitudinal construction joints and transverse deck cracking. Despite past studies and best practices, transverse cracking persists and is often observed more on one side of the deck during construction, and no definitive explanation has been provided. As such, the objective of this study is to present a mechanics-based method for assessing transverse deck cracking in bridges during staged construction. Demonstrated on two bridges that underwent staged construction, the assessment method provides insights into the persistence of the issue and provides a mechanics-based explanation for observations of transverse cracking sometimes being observed only on one side of the bridge. The method, based on the superposition of strains, considers the sequence of steps in the construction process and estimates strain demands in the concrete decks at each stage, considering variations of the structural configuration, applied loads, and time-dependent behaviors. The results of the assessment agree with finite-element analysis results while requiring less model development and computational effort. The estimated strain history is then used to assess whether transverse cracking occurs by comparing the demand to the concrete's tensile strength in time. The method is demonstrated on a new bridge constructed in stages and an existing bridge that underwent rehabilitation via staged construction. The results of the demonstrations suggest the importance of evaluating both the open and closed portions of bridge decks at each stage, as each portion has different structural and mechanical properties and loading demands. The assessment results are qualitatively validated based upon information from postconstruction bridge inspections. Furthermore, the method can be used to gain insight into mitigating transverse deck cracking and support decision-making for bridge construction practices. [ABSTRACT FROM AUTHOR]

In this study, a procedure for interpreting impact-echo data in an automated, simple manner for detecting defects in concrete bridge decks is presented. Such a procedure is needed because it can be challenging for inexperienced impact-echo users to correctly distinguish between sound and defective concrete. This data interpretation procedure was developed considering the statistical nature of impact-echo data in a manner to allow impact-echo users of all skill levels to understand and implement the procedure. The developed method predominantly relies on conducting segmented linear regression analysis of the cumulative probabilities of an impact-echo data set to identify frequency thresholds distinguishing sound concrete from defective concrete. The accuracy of this method was validated using two case studies of five slab specimens and a full-scale bridge deck, each containing various typical defects. The developed procedure was found to be able to predict the condition of the slab specimens containing shallow delaminations without human assistance within 3.1 percentage points of the maximum attainable accuracy. It was also able to correctly predict the condition of the full-scale bridge deck containing delaminations, voids, corrosion damage, concrete deterioration, and poorly constructed concrete within 3.5 percentage points of the maximum attainable accuracy. [ABSTRACT FROM AUTHOR]

Highway agencies monitor the condition of thousands of bridge decks every year. Even though Ground Penetrating Radar (GPR) has been used in bridge-deck evaluation, Step-Frequency GPR (SF-GPR) provides advanced condition assessment yet requires extensive and complex post-processing analysis. An SF-GPR analysis system was recently developed and used for monitoring the condition of all the bridge decks in the state of Maryland. The objective of this study was to develop a bridge deck condition rating approach using fuzzy sets modeling on the SF-GPR data and analysis. The fuzzy sets membership functions needed to reflect rating score categories similar to those considered in the National Bridge Inventory (NBI) database for uniformity. Thus, the fuzzy sets modeling was built considering nine condition membership functions. The overall bridge deck condition score leading to each of the nine condition states was based on both physical and condition-related bridge deck parameters as obtained from the SF-GPR analysis. The modeling approach is presented herein, along with two bridge deck examples. The proposed novel fuzzy sets modeling can be considered for possible adoption elsewhere where similar GPR systems are used. [ABSTRACT FROM AUTHOR]

Experimental and numerical analyses of eight in-plane restrained slabs (1425 mm (length) × 475 mm (width) × 150 mm (thickness)) reinforced with glass fiber-reinforced polymer (GFRP) bars are reported in this paper. The test slabs were installed into a rig, that provided 855 kN/mm in-plane stiffness and rotational stiffness. The effective depths of the reinforcement in the slabs varied from 75 mm to 150 mm, and the amount of reinforcement changed from 0 to 1.2% with 8, 12, and 16 mm bar diameters. A comparison of the service and ultimate limit state behavior of the tested one-way spanning slabs shows that a different design approach is necessary for GFRP-reinforced in-plane restrained slabs that demonstrate compressive membrane action behavior. Design codes based on yield line theory, which considers simply supported and rotationally restrained slabs, are not sufficient to predict the ultimate limit state behavior of restrained GFRP-reinforced slabs. Tests reported a higher failure load for GFRP-reinforced slabs by a factor of 2, which was further validated by numerical models. The experimental investigation was validated by a numerical analysis, and the acceptability of the model was further confirmed by consistent results obtained by analyzing in-plane restrained slab data from the literature. [ABSTRACT FROM AUTHOR]

This paper presents a case study on the evaluation of bridge decks using various nondestructive test methods. In consultation with a local transportation agency, five representative bridges are selected and assessed by qualitative/empirical (visual inspection and chain drag) and quantitative (ground-penetrating radar [GPR] and rebound hammer) approaches. The primary interest lies in quantifying delaminated areas in deck concrete, which has been a major problem in the bridge engineering community because conventional GPR contours provide a wide range of deterioration that differs from the amount of actual repair. A consistent condition rating of 7 has been assigned to all decks over a decade old, aligning with the outcomes of chain drag: delamination of less than 3.31% of the entire deck area. The variable scanning rates of GPR (4 to 20 scans/ft [13 to 66 scans/m]) influence contour mapping, whereas mutual correlations associated with these rates are insignificant. A tolerable range of ±20% is suggested for interpreting GPR contour maps at a 95% confidence interval. The performance threshold limit of 20% used to identify degraded concrete in rebound hammering exhibits a coefficient of correlation of 0.967 against GPR-based deterioration; however, the results of these methods deviate from the areas of actual repair. For practical implementation, analytical and computational models are formulated to decompose the intensity of GPR scales into two categories: initiation and progression of corrosion (0 to 39%) and delamination of deck concrete (40 to 100%), which show good agreement with the repaired areas. Parametric investigations emphasize the significance of reinforcing bar spacing and concrete cover in determining the extent of delamination in the concrete decks. [ABSTRACT FROM AUTHOR]

This paper presents a new bridge deck reinforcement alternative using hybrid reinforced concrete (Hybrid) consisting of Glass Fiber Reinforced Polymer (GFRP) rebar and alkali-resistant fiberglass composite macrofibers added to the concrete mixture. Fiberglass composite macrofibers are a miniaturized GFRP reinforcing bar that is a composite of resin and glass fibers. An experimental testing program and analytical modeling were conducted to evaluate the structural performance at the service and ultimate limit states. Thirteen full-scale bridge deck specimens were constructed and tested under static and fatigue loading. The fatigue loading was applied up to two million cycles at a frequency of 4 Hz. Post-fatigue, the specimens were tested to failure to compare pre-and post-fatigue behavior. Simplified and moment-curvature analytical models were used to predict the specimens' flexural strength at the ultimate level, and both were found to be accurate for predicting pre- and post-fatigue strength. Deflection and crack width were monitored throughout the fatigue loading, and these values were compared to the recommended AASHTO LRFD serviceability limits. Testing and analytical results showed that the Hybrid deck is a viable alternative to steel-reinforced and GFRP-reinforced bridge decks for flexural behavior. The service and ultimate level behavior of each bridge deck type was adequate as compared to the AASHTO LRFD service limits. The exceptional post-peak energy absorption demonstrated by the Hybrid adds ductility to previously elastic GFRP reinforced sections. [ABSTRACT FROM AUTHOR]

Reinforcement corrosion is a leading cause of damage in concrete bridge decks, resulting in cracking and spalling in the concrete cover. Recently, ground penetrating radar (GPR) emerged as a prominent non-destructive testing (NDT) for evaluating the corrosiveness of concrete structures. Although GPR provides real-time testing for concrete elements, the analysis and interpretation of GPR data can be complex and time-consuming. To this end, this paper introduces a comprehensive methodology for a fully automated GPR data interpretation in the context of reinforcement corrosion evaluation. The developed method encompasses robust rebar picking and corrosion mapping. The rebar picking is realized by employing advanced waveform analysis and a three-step automated thresholding approach. Following rebar picking and data extraction, corrosion mapping is performed, stepping on a statistically optimized amplitude thresholding process. The developed rebar picking module achieved more than 98% precision and recall. Furthermore, the standardized corrosion assessment methodology precisely pinpointed potential corroded areas. [Display omitted] • Waveform analysis and three-step thresholding realized automated rebar recognition. • Corrosion is precisely mapped using standardized analysis and optimized thresholds. • The model achieved high rebar picking accuracy and accurate corrosion mapping. • The proposed framework advances strides toward a smart bridge inspection. [ABSTRACT FROM AUTHOR]

This study investigated the variation of bulk resistivity (BR) and charge passed for various high-performance concrete (HPC) mixtures based on significant factors (i.e., geometric size, operation frequency, and mixture constituents and proportions) using three testing instruments. These instruments were a surface resistivity (SR) meter and two bulk conductivity meters: one for using the BR data at a constant frequency, and the other at a wide range of frequencies. These HPC mixtures were categorized into several groups based on various supplementary cementitious materials (SCMs). The variation and distribution of BR and the charge passed were investigated and statistical analysis results showed that the addition of SCMs and their varying replacement level remarkably influenced the reduction of charge passed in each group over an extended period. The results revealed that, for fly ash-based ternary mixtures, the addition of 3% metakaolin or 12% silica fume resulted in the highest reduction of charge passed over time (82% and 90%, respectively). For cost purposes, 5% silica fume replacement in ternary mixtures was chosen as an optimal solution. Finally, this study offered promising options for charge passed computation to assess corrosion in light of simple, rapid, and reliable SR/BR measurement. [ABSTRACT FROM AUTHOR]

Highway agencies monitor the condition of thousands of bridge decks every year. Even though Ground Penetrating Radar (GPR) has been used in bridge-deck evaluation, Step-Frequency GPR (SF-GPR) provides advanced condition assessment yet requires extensive and complex post-processing analysis. An SF-GPR analysis system was recently developed and used for monitoring the condition of all the bridge decks in the state of Maryland. The objective of this study was to develop a bridge deck condition rating approach using fuzzy sets modeling on the SF-GPR data and analysis. The fuzzy sets membership functions needed to reflect rating score categories similar to those considered in the National Bridge Inventory (NBI) database for uniformity. Thus, the fuzzy sets modeling was built considering nine condition membership functions. The overall bridge deck condition score leading to each of the nine condition states was based on both physical and condition-related bridge deck parameters as obtained from the SF-GPR analysis. The modeling approach is presented herein, along with two bridge deck examples. The proposed novel fuzzy sets modeling can be considered for possible adoption elsewhere where similar GPR systems are used.

The overall goal of this project was to evaluate with available cores the presence of alkali-silica reaction (ASR) in California bridges and pavements, to develop procedures for evaluation of ASR by Caltrans staff, and, potentially, to investigate several locations suspected of having ASR damage. This report summarizes the creation of an inventory for cores taken from bridges and pavements in previous projects, the results of visual inspection and strength testing to identify the potential presence of ASR, and the development of a draft approach for Caltrans staff to evaluate the potential for ASR in bridges and pavements. A spreadsheet database was prepared for storing inventory data for 265 pavement cores with four inch (100 mm) diameter and 311 bridge cores with two inch (50 mm) diameter. Most of the bridge cores were from the San Francisco Bay Area, while the pavement cores were collected from across the state. Visual inspection was performed on 259 of the pavement cores (including multiple samples from some of the pavement cores) and 80 of the bridge cores (those with lengths greater than the three-inch minimum required for evaluation of ASR) using the Damage Rating Index (DRI) method. None of the cores showed the likelihood of an ASR issue, as defined by a DRI greater than 2,000, although a few cores showed a small number of ASR features. Comparison of the ages of the bridges and the ASR damage rating index for the cores showed almost no trend, and showed no apparent differences between cores from bridges built before and after 1995, approximately when Caltrans changed specifications to reduce the risk of ASR. Most of the pavement cores tested had unconfined compressive strength (UCS) less than 8,700 psi (60 MPa) and the median of the UCS of the pavement cores was approximately 6,100 psi (42 MPa). Most of the pavement cores tested had densities less than 156 pcf (2,500 kg/m3 ) and the median of the UCS of the pavement cores was approximately 147 pcf (2,350 kg/m3 ). No significant correlation was found between the UCS and the density of the pavement cores tested, although the UCS strengths generally increased with increased density. The bridge cores were too small in diameter for strength and density testing. An integrated spreadsheet database was prepared for storing all relevant data for all cores, including test results from all tasks (DRI, UCS, and density). A draft guideline was developed for visual inspection of concrete cores to identify signs of potential ASR-related distresses and to support decisions regarding the need for a further detailed investigation for ASR. The guideline describes step-by-step inspection procedures and selection criteria for a further detailed examination, with relevant example pictures showing different severity levels of potential ASR distresses.

Detecting the corrosive environment of reinforced concrete (RC) bridge decks is of critical importance for evaluating the reliability and safety of bridge structures. However, accurately and automatically detecting a corrosive environment with traditional methods is challenging. This paper proposes a method for the automatic corrosive environment detection of bridge decks from ground-penetrating radar (GPR) data based on the single-shot multibox detector (SSD) model. This method can be divided into three steps: data preprocessing, automatic rebar picking, and corrosive environment mapping. First, the GPR data are preprocessed to enhance the contrast of the hyperbolic feature in GPR B-scans. Then the rebars in the B-scan images are automatically picked up by the trained SSD model. Finally, the corrosive environment contour map of the bridge deck is generated with the rebar reflection amplitudes after depth correction. The SSD model was trained with 10,316 B-scan images and tested with 2,578 images. The 300×300-pixel B-scan image typically included three to five hyperbolas. A case study with GPR data from a tested bridge was employed to validate the feasibility of the proposed method. The results show that the accuracy of the automatic corrosive environment detection method can reach 98% and is considerably higher than that of commercial software methods. [ABSTRACT FROM AUTHOR]

The deteriorating condition of infrastructure, combined with fiscal limitations experienced by many agencies, necessitates increased service life of bridges. Maintenance and preservation methods such as overlays and sealers have been known to protect bridge decks from deterioration, while also extending a bridge's service life. It is important to understand the characteristics of various overlay types to make informed maintenance decisions, thus assessing and comparing the performance of thin epoxy overlays and low slump dense concrete (LSDC) overlays is desirable. To evaluate the performance of these two overlay types, the chloride resistance and long-term bond strength of the overlays were assessed. Three bridges were chosen to install each overlay type, with corresponding field and laboratory evaluations performed. The above tests results indicated that the initial bond strength of both overlays is good, but that the thin epoxy overlays showed decreased performance after 300 F/T cycles. The bond performance of the LSDC remain unchanged for the duration of the freeze–thaw testing, indicating superior long-term performance. As expected, the epoxy overlay performed much better than the LSDC overlay with respect to chloride resistance. These performance metrics are important to keep in mind when selecting maintenance and rehabilitation methods for bridges. [ABSTRACT FROM AUTHOR]

Characteristic cracks in skewed bridges, detrimental to service performance, form in deck acute corners and run diagonally across deck span. This paper presents the relationship between skew and deck cracks, investigates crack mitigation strategies and documents changes in live load distribution caused by cracks. Finite element analyses of in-service steel and concrete girder bridges were performed and qualitatively validated. The analyses were used to study the influence of skew angle, deck reinforcement amount and orientation, end diaphragm and girder restraint on deck strains and on live load distribution for shear (i.e., live load distribution to girders as vertical shear forces) from cracked decks to girders. The results showed that high skew induces stresses high enough to cause typical diagonal deck cracking on skewed bridges due to deck shrinkage. Restraint provided by end diaphragms, particularly by full depth concrete diaphragms and diaphragms connected to deck, magnify deck stresses. Orienting transverse deck reinforcement perpendicular to bridge centreline is more effective than parallel to substructure. Larger deck reinforcement cross-sectional areas increased deck restraint and likelihood of cracking. Shear live load reaction in exterior girders of the bridges studied increased by 35% due to deck cracks, although it remained smaller than interior girder reaction. [ABSTRACT FROM AUTHOR]

Experimental and numerical analyses of eight in-plane restrained slabs (1425 mm (length) × 475 mm (width) × 150 mm (thickness)) reinforced with glass fiber-reinforced polymer (GFRP) bars are reported in this paper. The test slabs were installed into a rig, that provided 855 kN/mm in-plane stiffness and rotational stiffness. The effective depths of the reinforcement in the slabs varied from 75 mm to 150 mm, and the amount of reinforcement changed from 0 to 1.2% with 8, 12, and 16 mm bar diameters. A comparison of the service and ultimate limit state behavior of the tested one-way spanning slabs shows that a different design approach is necessary for GFRP-reinforced in-plane restrained slabs that demonstrate compressive membrane action behavior. Design codes based on yield line theory, which considers simply supported and rotationally restrained slabs, are not sufficient to predict the ultimate limit state behavior of restrained GFRP-reinforced slabs. Tests reported a higher failure load for GFRP-reinforced slabs by a factor of 2, which was further validated by numerical models. The experimental investigation was validated by a numerical analysis, and the acceptability of the model was further confirmed by consistent results obtained by analyzing in-plane restrained slab data from the literature.

This paper presents a new bridge deck reinforcement alternative using hybrid reinforced concrete (Hybrid) consisting of Glass Fiber Reinforced Polymer (GFRP) rebar and alkali-resistant fiberglass composite macrofibers added to the concrete mixture. Fiberglass composite macrofibers are a miniaturized GFRP reinforcing bar that is a composite of resin and glass fibers. An experimental testing program and analytical modeling were conducted to evaluate the structural performance at the service and ultimate limit states. Thirteen full-scale bridge deck specimens were constructed and tested under static and fatigue loading. The fatigue loading was applied up to two million cycles at a frequency of 4 Hz. Post-fatigue, the specimens were tested to failure to compare pre-and post-fatigue behavior. Simplified and moment-curvature analytical models were used to predict the specimens’ flexural strength at the ultimate level, and both were found to be accurate for predicting pre- and post-fatigue strength. Deflection and crack width were monitored throughout the fatigue loading, and these values were compared to the recommended AASHTO LRFD serviceability limits. Testing and analytical results showed that the Hybrid deck is a viable alternative to steel-reinforced and GFRP-reinforced bridge decks for flexural behavior. The service and ultimate level behavior of each bridge deck type was adequate as compared to the AASHTO LRFD service limits. The exceptional post-peak energy absorption demonstrated by the Hybrid adds ductility to previously elastic GFRP reinforced sections.

This study investigated the variation of bulk resistivity (BR) and charge passed for various high-performance concrete (HPC) mixtures based on significant factors (i.e., geometric size, operation frequency, and mixture constituents and proportions) using three testing instruments. These instruments were a surface resistivity (SR) meter and two bulk conductivity meters: one for using the BR data at a constant frequency, and the other at a wide range of frequencies. These HPC mixtures were categorized into several groups based on various supplementary cementitious materials (SCMs). The variation and distribution of BR and the charge passed were investigated and statistical analysis results showed that the addition of SCMs and their varying replacement level remarkably influenced the reduction of charge passed in each group over an extended period. The results revealed that, for fly ash-based ternary mixtures, the addition of 3% metakaolin or 12% silica fume resulted in the highest reduction of charge passed over time (82% and 90%, respectively). For cost purposes, 5% silica fume replacement in ternary mixtures was chosen as an optimal solution. Finally, this study offered promising options for charge passed computation to assess corrosion in light of simple, rapid, and reliable SR/BR measurement.

Abstract. High-speed lines are one of the safest modes of transport, despite the special conditions for moving the wheel along the rail. The urgent task is to ensure the sustainable motion of the wheel along the rail over the bridges in high-speed traffic. A feature of high-speed lines (HS lines) is the practical achievement of critical speeds that cause resonance of bridge deck structures. Cases of rolling stock derailments on high-speed lines are not frequent. The article provides information about rolling stock derailments on high-speed rail and its consequences. Standards for the stability of wheels on rails in various countries with high-speed rail were considered. On the bridges of high-speed lines there are not many elements of the track that are strong dampers — the roadbed, its base and ballast. Due to the lack of damping elements, the damping properties of the bridge deck are of great importance. When driving over the bridge with critical speeds causing near-resonance oscillations, the force in the wheel—rail contact may drop to zero with the risk of derailment. Insufficient damping poses a threat to traffic safety. Thus, one of the most important dynamic parameters — damping — is a problem for a ballastless track on high-speed railway bridges. Considerations are given for the correct determination of stiffness associated with damping and affecting the interaction of rolling stock and bridge deck. It is shown that in case of insufficient damping at the fastening points on the bridges, the risk of derailment increases due to a fall of the vertical force below the permissible limit at the wheel—rail contact. Results of computer performed experiments are presented, confirming that it is precisely the significant oscillations of the bridge deck structures that are a safety hazard, since when the first car passes, the force at the contact of the wheel and rail for the first wheelset is safe. Requirements for damping parameters are given, ensuring reliable contact of the wheel and rail with significant fluctuations in bridge deck structures on high-speed lines. Results are presented, showing the dependence of required damping on the stiffness of intermediate rail fasteners.

Fiber-reinforced polymer (FRP) composite bridges are usually constructed for rapid installation. The durability of the bridge is increased by stiffness, strength to weight ratio, and corrosion resistance. The main factors on which the design of the composite sandwiched bridge considerably depends are ply layers, material system, alignment of ply angles, and thickness of the core. In this work, a parametric design study for a bridge using finite element analysis (FEA) is presented. Two types of composite materials—carbon fiber reinforced polymer (CFRP) and glass fiber reinforced polymer (GFRP)—were used as the sandwich structure's skin, and three different types of woods were used as a core. Different design configurations were acquired based on material and instability constraints by using Euro-codes. Failure criterion of Tsai-Hill, Tsai-Wu, MS, equivalent stress, and maximum shear stress were implemented to analyze the overall failure of the bridge deck under Ultimate Limit State (ULS) conditions. The total deformation was examined under Serviceability Limit State (SLS) conditions, and the results were compared and verified by the previous study. The core was also examined using the core-factor and increasing the thickness of the core through parametric modeling. [ABSTRACT FROM AUTHOR]

Wind barriers are nowadays commonly placed on bridges to protect vehicles from adverse cross-wind effects. In addition to this beneficial influence, wind barriers may adversely affect the bridge dynamic stability. This is particularly exhibited for long-span cable-supported bridges. It is therefore the scope of the present study to analyze the effects of wind barriers on aerodynamic and aeroelastic characteristics of bridge-deck sections of long-span cable-supported bridges together with the respective flow characteristics around bridge-deck sections. The focus is on various arrangements of wind barriers, i.e., (1) wind barriers placed at the windward bridge-deck edge only; (2) wind barriers placed at the leeward bridge-deck edge only; and (3) wind barriers placed at both windward and leeward bridge-deck edges. This was carried out experimentally on small-scale models in a boundary layer wind tunnel. Three typical bridge-deck section models were studied, i.e., Great Belt (Denmark), Kao-Pin Hsi (Taiwan), and Golden Gate (United States). The galloping susceptibility of the bridge-deck sections in all arrangements of wind barriers proved to be the same, as is the case for the empty bridge-deck sections without wind barriers; i.e., from this point of view, wind barriers do not adversely bridge dynamic stability. However, in configurations with the windward wind barrier only, as well as both windward and leeward wind barriers, the flutter susceptibility of the bridge-deck sections increases substantially; i.e., the critical flow velocity for the bridge flutter decreased significantly in comparison with the respective empty bridge-deck sections. For the leeward wind barrier only, the flutter susceptibility of the bridge-deck sections did not change and remained the same as it was for the empty bridge-deck sections. The empty bridge-deck sections do not exhibit any significant change concerning their susceptibility to flutter for various turbulence levels of the incoming freestream flow. The flutter susceptibility of cable-supported bridges equipped with wind barriers is lower in more turbulent incoming flows. The bridge decks with wind barriers are more resilient to flutter in more turbulent winds. Shear layers that separate from the top of the wind barrier may have an important role in the self-excited lift force and the pitch moment and, consequently, the dynamic behavior of bridge decks. [ABSTRACT FROM AUTHOR]

The Netherlands has a large number of thin, transversely prestressed concrete bridge decks, cast in-situ between flanges of prestressed concrete girders dating back to the 1960s and 1970s. These bridges are critical in shear when analyzed using EN 1992-1-1:2005; however, in reality, they show no significant signs of distress, possibly because of residual bearing (punching shear) capacity arising from compressive membrane action. Since these bridges are old, it is an astute approach to check whether they can be used for a few more decades, provided they are safe and reliable against modern traffic loads. The results could then be applied to a wider range of structures, especially in developing countries facing economic constraints. A prototype bridge was selected and experimental, numerical and theoretical approaches were used to investigate its bearing capacity. Respective coefficients of variation of 11% and 9% were obtained when the experimental and the finite element analysis punching loads were compared with the theoretical results. This led to the conclusion that the existing transversely prestressed concrete bridge decks still have sufficient bearing capacity and considerable cost savings can be made if compressive membrane action is considered in the analysis. [ABSTRACT FROM AUTHOR]

This paper presents the results from an investigation into the performance of concrete bridge decks designed with the empirical design method. Compressive membrane/arching action (CMAA) behavior in bridge decks has been known for many years and has been adopted in design codes by some countries. AASHTO LRFD Bridge Design Specifications have provisions that allow the use of the empirical deck design method, which is based on CMAA. Despite the savings in deck reinforcement that the empirical method offers compared with the traditional method, the majority of state departments of transportation (DOTs) do not allow the use of the empirical method. In part, this is due to the fact that some of the current method limitations (e.g., lack of sufficient overhang length) are impossible to satisfy in phased construction and future widening scenarios. In this study, the performance of concrete bridge decks designed with the empirical design method was investigated through extensive experimental testing of a full-size specimen. The fabricated deck specimen mimicked a widening scenario, where the deck was supported on two prestressed concrete Florida I-Beams. Nine tests were conducted at different locations along the bridge deck under service and failure load levels. The results show that deck slabs designed according to the empirical design method are capable of meeting AASHTO LRFD serviceability and strength requirements. The outcome of this research study provides information to DOT officials regarding the feasibility of using the empirical method for the design of bridge decks under conditions not currently covered by AASHTO LRFD provisions. [ABSTRACT FROM AUTHOR]

Grillage decks made of reinforced concrete (RC) with more than 40–60 years of service life may exhibit localised areas of severe damage or even entire elements exceeding the serviceability limits. In these cases, it is essential to quickly and efficiently assess the structure's safety margins, and, in the worst cases, to also verify whether the damaged deck's residual bearing capacity is sufficient for it to be used as a platform for the repair works. This article proposes an assessment based on a non-linear RC finite element specialised in dealing with systems working in bending and torsion. The damage, measured at a particular time after construction, is modelled by a reduction of the reinforcement section, supposed to be induced by chlorides diffusion and investigated through a Cellular Automata algorithm. Such an approach is applied in studying a bridge deck, having an edge beam damaged by leakage of salted water from the road platform. The results give a thorough description of the structural behaviour and the deformed shapes help in understanding the redistribution process of the internal forces. These results may provide a reliable reference to plan proper maintenance actions as well as to establish a hierarchy of repairing and strengthening interventions. [ABSTRACT FROM AUTHOR]