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This study investigates the wind‐induced flutter phenomenon of long‐span suspension bridges. A mathematical model is established using the energy method, considering the nonlinear aeroelastic behavior of a bridge deck constrained by vertical suspenders under cubic nonlinear damping. The aerodynamic self‐excited force is obtained using the Scanlan flutter theory. The critical state of flutter and the relationship between the amplitude and parameters of the limit cycle oscillation (LCO) are obtained by solving the nonlinear flutter equation using the average perturbation method. The Hopf bifurcation is confirmed to occur in the critical state of the nonlinear motion model using the Jacobian matrix. The results are verified using the Runge–Kutta numerical method, and it is found that the nonlinear response of the flutter LCO is in general agreement with the numerical solution. The study also shows that the degenerate Hopf bifurcation appears at the critical state under the condition of lower cubic damping coefficient, and the nonlinear flutter bifurcation changes from a degenerate Hopf bifurcation to a supercritical Hopf bifurcation as the cubic damping coefficient grows. [ABSTRACT FROM AUTHOR]

How bridge refurbishment projects are performed requires a trade-off between the speed and cost of the project and the amount of traffic disturbances during the project. A possible way to help reach a better balance between these two extremes is the ASTRA Bridge developed in Switzerland. The ASTRA Bridge is a 236-meter long steel ramp system on wheels, which is placed on top of the bridge deck undergoing refurbishment to enable vehicles to continue to pass over the bridge while construction work progresses underneath. This study illustrates new refurbishment processes by using the ASTRA Bridge and presents the first quantitative analysis of the effects of using the ASTRA Bridge on the time, costs and traffic disturbances associated with bridge refurbishment. The bridge investigated is a short-span (50 m long) highway bridge requiring refurbishment of its superstructure. The analysis indicates that the use of the ASTRA Bridge resulted in reductions in duration and costs (14% and 3% for the example), and a substantial reduction in user costs (51% for the example). Although more analysis is required for different types of refurbishment projects, the initial results indicate that the ASTRA Bridge may become an integral part of future highway bridge refurbishment projects. [ABSTRACT FROM AUTHOR]

This study investigates the vulnerability of long-span suspension bridges to spatially variable vertical ground motions (SV-VGMs). While of recognized importance, a comprehensive understanding of this topic has been traditionally limited by the unavailability of an adequate number of arrays of motions. In this work, 10 simulations of a large-magnitude Hayward Fault earthquake are utilized to perform site-specific structural response assessments of a suspension bridge under different load scenarios. A detailed nonlinear model representative of the West San Francisco-Oakland Bay Bridge is employed as the case study structure. Four sets of nonlinear time-history analyses are performed with and without VGMs and with and without the incorporation of spatial variability to offer the basis for a complete comparison of the demand distributions across different load cases. Results indicate that VGMs largely influence the response of the bridge decks in the vertical direction, with an increase in drifts up to 2× for the case of synchronous input and up to 2.5× for the case of asynchronous inputs. The analysis of the bridge response in the time and frequency domain across all load cases reveals a high sensitivity of the decks' response to minor time lags in input motions of comparable amplitude, which are seen to activate the contribution of higher modes to the structural response. Evidence from this study points to the potential of severely underestimating structural demands if the (even limited) spatial variability of the input motions is not incorporated correctly. For the case study structure, the probability of exceeding the onset of nonlinearity in the short decks at the design earthquake level is seen to increase by a factor of about two when considering SV-VGMs as opposed to synchronous horizontal motions only. [ABSTRACT FROM AUTHOR]

This article provides a comprehensive state-of-the-art review of research on bridge deck fatigue under moving wheel loads and compares it to conventional fixed-point pulsating load fatigue. An overview and a brief history of the evolution of this test method from around the world are provided. The effect of key parameters on fatigue life and performance under moving loads are discussed, including loading magnitude and stress ratio, loading footprint, boundary conditions, loading eccentricity, loading frequency, dynamic effect and impact, reinforcement layout, slab thickness, crack control, concrete strength, and environmental exposure conditions. The fatigue accumulation rule and the incremental step (staircase) rolling load method are discussed. Cracking and failure mechanisms in slabs under rolling loads are presented and compared. It is clearly demonstrated that fixed-point pulsating fatigue loads inadequately simulate fatigue damage, stiffness degradation, and cracking patterns induced by rolling loads. For example, one rolling load cycle is shown to be equivalent to 80–1,800 pulsating load cycles. Varying the magnitude of the rolling load (dynamic effect) further reduces the fatigue life. Decreasing the spacing of the transverse rebar and compression reinforcement both can increase susceptibility to crack initiation, potentially reducing fatigue life. Environmental factors, particularly moisture intrusion, drastically reduced fatigue life. A conversion factor of stiffness degradation from pulsating to equivalent rolling load fatigue is proposed. Finally, recommendations for future work in this field are proposed. [ABSTRACT FROM AUTHOR]

During seismic ground shaking, the motion of a soil–pile system is different from that of the free field due to seismic soil–structure interaction (SSI). Kinematic soil–pile interaction is known to cause significant filtering of the ground motion, resulting in the foundation input motion (FIM) differing from the free-field ground motion. In certain situations, where embedment of the pile cap is ensured, such as in the case of a piled raft (PR), previous numerical studies have shown that embedment effects can cause additional alterations to the FIM. In this work, we investigated the influence of an embedded pile cap on the seismic response of a pile group (PG) employing physical and numerical modeling. A shaking-table test program was designed to investigate the embedment effects on the seismic response of a scaled 2 × 2 PG in clay, in the absence of superstructure inertia. Two identical PG models––one embedded and the other free standing––were subjected to a series of harmonic and white-noise signals, following which, the responses were assessed in terms of the transfer functions and spectral ratios. The ratio of translational response amplitudes of the PR to the PG indicated that embedment effects can lead to significant filtering of the ground motion at higher excitation frequencies. Unique experimental evidence is presented showing that pile-cap embedment can result in additional filtering of the ground motion, even for a highly nonlinear soil response. The results from the experimental program were complemented by numerical analyses of a real-world bridge support system where the influence of embedment on the bridge deck response was studied for a set of seismic ground motion records of varying intensity. We confirmed that the embedment effect is a SSI problem, independent of the earthquake-induced soil nonlinearity, and loss of the soil–pile-cap contact can lead to higher energy being transmitted to the superstructure. [ABSTRACT FROM AUTHOR]

Due to the influence of the three-dimensional (3D) effect, the identification accuracy of 3D aerodynamic admittance functions (AAFs) would inevitably be influenced by the ratio of turbulent integral scale to model dimension (dimensionless integral scale). For this, the two-dimensional (2D) AAFs of a streamlined bridge deck in different turbulent flow fields are experimentally investigated, wherein the 2D AAF is determined by separating out the 3D effect from the 3D AAF. Consistent with the previous studies, the 3D AAFs exhibit significant flow field dependence, and are less than the Sears function in low-frequency range. Different from the 3D AAF, the 2D AAFs obtained in two turbulent flow fields are higher than the Sears function and have a good consistency in various turbulent flows. It can be therefore considered that the identification accuracy of 2D AAF of a streamlined bridge deck is not related to the dimensionless integral scale, which might avoid the possible deviation caused by the mismatch of integral scale in the wind tunnel test. An empirical formula for the 2D AAF of a streamlined bridge deck is then proposed by fitting the experimental data. In addition, to further examine the validity of above conclusion, a comparison between the 3D AAFs of a streamlined bridge deck measured in other wind tunnel tests and the predictions calculated with the present 2D AAF is also made. [ABSTRACT FROM AUTHOR]

This study conducts a rigorous analysis of the moisture diffusion mechanism that undermines the adhesive layer of epoxy asphalt (EA) pavement on steel bridge decks, thereby fostering latent distresses. Furthermore, a novel and highly efficacious approach for detecting these concealed distresses is introduced. The findings of water vapor permeability tests conclusively reveal that the moisture diffusion coefficients of the upper and lower layers of the EA pavement stand at 0.1238 mm2/s and 0.0879 mm2/s, respectively, highlighting this disparity as the primary trigger for concealed issues like pavement delamination and swelling. Leveraging the combined capabilities of three‐dimensional ground‐penetrating radar (3D‐GPR) and infrared thermography, this research reliably detects, identifies, and pinpoints concealed defects at three strategic locations on the steel bridge deck. The integration of these two technologies has exhibited remarkable proficiency in identifying concealed damages. Consequently, this study lays a substantial foundation for evaluating and detecting concealed distress in EA pavements atop steel bridge decks. [ABSTRACT FROM AUTHOR]

Translation abstract Mattensteg, rehabilitation and relocation of a 150 year old frame bridgeAt the existing Mattensteg – a 150 year old riveted truss‐girder steelbridge, a condition survey in 2005 revealed that the local concrete bridge deck was in poor condition. Based on this assessment and the bridge‘s previous service life, it was decided to carry out a comprehensive renovation of the bridge. At the same time, the AWEL (Amt für Abfall, Wasser, Energie und Luft des Kantons Zürich) planned to renew the Platzspitzwehr. In recent years, access for maintenance work on the weir has been via the Platzspitz, as the Mattensteg cannot be used by heavy vehicles. This is unsatisfactory for the park with its protected plane trees. It was therefore decided to build a new service bridge at the site of the Mattensteg for the construction and future maintenance work. However, as the existing Mattensteg is a listed building, the existing old truss bridge was to be retained, moved some 80 m upstream and rebuilt. The reinforcements were riveted analogously to the existing construction. Due to the protected status of the building, the new piers will be built in the original style with stairs. As a result, the footbridge is no longer accessible to cyclists, wheelchair users or maintenance vehicles. The construction costs for the relocation, the construction of the new supports and piers as well as the restoration of the bridge amount to CHF 2.5 mio. [ABSTRACT FROM AUTHOR]

Generalized structural and aerodynamic torsional stiffness of a suspension bridge with a main span length of 3000m are discussed first qualitatively in terms of analytical models. Two torsional divergence (TD) modes, symmetric and asymmetric, are compared in terms of the evolution of generalized torsional stiffness properties. It demonstrates that symmetric TD occurs prior to the asymmetric TD in a vast range of main span lengths. Numerical simulations of TD are then performed by the static finite element (FE) method. The results turn out a much lower critical wind speed of TD presented by the analytical model, due to stiffness degradation caused by main cable deformations. Finally, the effects of two types of countermeasures are examined. The replacement of the original deck section by a central slotted one can boost the critical wind speed of TD by 30%. Widening the main cable spacing enhances almost linearly the system’s critical wind speed. A combined countermeasure of a slotted bridge deck and widened main cable spacing stabilizes substantially the system’s aerodynamic static stability, resulting in a 45% increase in the critical wind speed of TD. [ABSTRACT FROM AUTHOR]

In order to study the influence of the lifting force arrangement on the mechanical performance of the long-span steel-concrete composite girder which using the lifting-composing construction method, based on the Qinhe grand bridge along the Taihang expressway, the effects of different first and secondary lifting force, the number and distance of lifting points on the stress, deformation, stability, and bridge deck compressive stress reserve of the steel-concrete composite girder were studied by using the Midas-Civil finite element software and a control variable method. The sensitivity of different factors on the steel-concrete composite girder was analyzed through variable normalization, moreover, the optimal scheme was selected, and the implementation effect was monitored on site. The results show that the stress of upper flange of the steel girder, bridge deck, and bridge deflection are most sensitive to the secondary lifting force, with sensitivities of 0.61, 1.95, and 0.16, respectively. The stress of lower flange of the steel girder is most sensitive to the number of lifting points, with a sensitivity of 0.20. The theoretical optimal pre-bending of Qinhe grand bridge is 78%, the final scheme arranges 5 groups of lifting points with distance of 11 m, and the first and the secondary lifting forces are 1 500 kN and 6 500 kN, respectively. The on-site monitoring results show that the construction effect of the scheme is consistent with the theoretical analysis results, and the on-site lifting force is reasonably arranged. The on-site monitoring results show that the implementation effect of the scheme is consistent with the theoretical analysis, and the lifting force is reasonably arranged. The research results can provide reference for similar projects. [ABSTRACT FROM AUTHOR]

This work focuses on the dynamic analysis of road bridges under large microsimulated traffic flows, contributing an efficient dynamic analysis framework for future fatigue, comfort or driving safety studies in which realistic interactions between vehicles are considered. Different strategies to define the loading vector in the governing dynamic equations are presented for bridges discretized with beam and shell elements. The proposed interpolation techniques for beam-like models include a recursive binary search and a novel vectorized strategy based on shape functions expanded to the entire length of the deck. These are applied to a short simply supported bridge and a very long cable-stayed bridge under traffic flows generated with a cellular automata microsimulation model. The strategies presented here reduce the computational time required in conventional load interpolation algorithms, particularly in long bridges subject to dense traffic flows. Finally, the binary search algorithm is applied to the study of bridge decks discretized with shell elements under microsimulated traffic, demonstrating that high vehicle densities increase the contribution of the transverse vibration of the slab and the potential discomfort of pedestrians. [ABSTRACT FROM AUTHOR]

This paper presents the effects of angles of attack (AOA) on the windproof effect of wind barriers and the driving safety of highway vehicles on a wide bridge girder. The aerodynamic force coefficients of the vehicles were obtained using the force measurement technique. Computational fluid dynamics simulations were employed to investigate the mean wind velocity field on the upper surface of the girder. A comparison was made between the aerodynamic forces on a vehicle at various AOA on a bridge deck with guardrails and a deck with wind barriers. The windproof effect of wind barriers at various AOA was accessed by the safety factor of a vehicle. The results showed that the maximum of the aerodynamic forces of vehicles was not typically observed at a 0° AOA. The windproof effect of wind barriers became more pronounced as the magnitude of the AOA increased. As AOA increases, the height of the low wind velocity zone above the deck shows an upward trend. Compared to the deck with the guardrails, the height of the low wind velocity zone was much higher in the presence of wind barriers. The increase in the height of the low wind velocity zone will result in a decrease in the aerodynamic side force and an increase in the rolling moment acting on vehicles. It is also noteworthy that the installation of wind barriers can cause a reduction of overturning and side-slip safety factors of vehicles at specific AOA. This suggests that the wind barrier may potentially compromise driving safety at specific AOA. [ABSTRACT FROM AUTHOR]

Bridge decks are the surface of bridges that carry the weight of the vehicles and pedestrians crossing over them. The design of bridge decks varies depending on the span, traffic volume, and material availability. But nowadays, the need for a sustainable approach is required. So, use of a sustainable material for construction and retrofitting purposes is the need of the hour. In the present study, a novel synthetic material polyurethane has been used in bridges. The study deals with the variation in skew angles to determine the response of the bridge deck. The response of natural frequencies on the bridge deck due to the variation in skewness and thickness of steel are analysed under simply supported and clamped boundary conditions. Further, the bridge deck is sandwiched using steel and polyurethane having different thicknesses, and the responses are recorded. Afterwards, a bridge deck is modelled using polyurethane as a special case, to pursue sustainability and justify the RRR (reduce, reuse, and recycle) concept of waste management. A comparative study is also performed between the isotropic steel deck and sandwiched deck by varying the skewness. The skew angle is varied from 0° to 60° with a difference of 10°, i.e., 0°, 10°, 20°, 30°, 40°, 50°, and 60°. The frequencies of the isotropic steel and sandwiched decks are increasing when the skewness is increased. Also, the decks may be modelled in a way to enhances the vibration behaviour by sandwiching the existing steel decks. The free vibration frequencies of the sandwiched decks are comparable to the steel deck of similar thickness, which shows the use of polyurethane as the core material does not affect the vibrational characteristics of the deck, while at the same time reducing the cost significantly. The research lays the groundwork for the creation of engineering recommendations that practitioners can use. [ABSTRACT FROM AUTHOR]

To address the challenges in predicting the aeroelastic phenomenon and the resulting wind-induced forces on slender bridges, a real-time aeroelastic hybrid simulation (RTAHS) system was developed. The RTAHS system directly measures the aerodynamic and aeroelastic forces through load cells. It controls the next step's position of the deck section model with linear motors by solving the governing equations of motion in real time. Given the complex shape of a bridge deck section geometry, load cells are chosen for force measurement instead of as pressure sensors. In the previous RTAHS system proposed by the authors, the inertial forces of a rectangular section model were eliminated from the measured forces under the assumption of the model's rigid-body motion. However, when conducting RTAHS experiments with a realistic bridge deck section model, increasing the mass ratio between the mass of the model and the target mass input to the hybrid system results in unstable vibrations. This instability is primarily attributed to forces generated by the model's flexibility. This study developed an improved RTAHS system, which took into account the inertial forces arising from the nonrigid motion of the flexible bridge deck section model. An accelerometer was additionally installed at the midpoint of the model, and the inertial forces caused by the nonrigid behavior were compensated using a calibration factor derived from impact hammer tests. This approach was validated by comparing the spring-supported experiments conducted on a realistic bridge deck section model. [ABSTRACT FROM AUTHOR]

Concrete bridge deck cracking can cause serious serviceability issues during a bridge's design life and compromise a bridge's structural strength. Early age concrete bridge deck cracking occurs within a month of the concrete deck being placed and prior to live load application. It can typically be attributed to two factors: (1) construction practices; and (2) concrete shrinkage. This article examines the continuous deck placement sequence approach and its influence on early age concrete bridge deck cracking. Although the continuous deck placement process is commonly used, studies related to stresses induced during this process and the potential for deck cracking when using this construction method are very limited to work conducted overseas. Consequently, a time-dependent analysis considering the continuous bridge deck placement sequence at a steel composite bridge is presented in this article to help explain possible causes of early age bridge deck cracking. The modular ratio approach discussed in the Eurocode 4 is incorporated to approximate the early age concrete elastic modulus. To show the significance of using a continuous placement sequence, tensile stresses along the bridge length centerline are compared with the allowable tensile stress at two times, six and twenty-seven days after the bridge deck construction is initiated. Additionally, the article includes a simplified approach for calculating maximum bridge thermal stresses. The study results in this article will serve to aid engineers in understanding possible factors resulting in early age bridge deck cracking when a continuous deck placement sequence is used for bridge deck construction. Practical Applications: Early age bridge deck cracking can typically be attributed to construction practices and concrete shrinkage. Most bridges are constructed using a sequential deck placement where the concrete bridge deck is placed in discontinuous segments in an order to minimize tensile stresses developing in the concrete bridge deck. Conversely, a continuous deck placement entails placing the concrete bridge deck from one end of the bridge to the other end continuously. Contractors prefer using a continuous deck placement because of the method's reduced construction time. The Arkansas Department of Transportation (ARDOT) has identified early age concrete bridge deck cracking at a disproportionate number of continuous steel girder bridges constructed using a continuous deck placement. Early age concrete bridge deck cracking develops when tensile stresses in the concrete bridge deck exceed the concrete's tensile strength. During the bridge construction phase, concrete self-weight, construction loads, and thermal shrinkage are the primary load contributors to early age concrete bridge deck tensile stress. Since most continuous girder steel bridges consist of multiple short spans, early age concrete bridge deck tensile stress is primarily due to resistance to thermal shrinkage. An equation is derived in the article to calculate an approximate value for the thermal shrinkage stress. Thermal shrinkage cracking is averted by implementing proper curing methods to ensure the concrete tensile strength exceeds the induced tensile stress. Proper curing includes moist curing and minimizing moisture loss by using concrete curing blankets. [ABSTRACT FROM AUTHOR]

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]

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Concrete structures such as bridge decks and road pavements are subjected to repetitive loading and are susceptible to fatigue failure. A simplified stress–strain analysis method that can simulate concrete behavior with a sound physical basis, acceptable prediction precision, and reasonable computation cost is urgently needed to address the critical issue of high-cycle fatigue in structural engineering. An equivalent fatigue constitutive model at discrete loading cycles incorporated into the concrete damaged plasticity model (CDPM) in Abaqus is proposed based on fatigue damage evolution. A damage variable is constructed from maximum fatigue strains, and fatigue damage evolution is described by a general equation whose parameters' physical meaning and value range are identified. With the descending branch of the monotonic stress–strain curve as the envelope of fatigue residual strength and fatigue damage evolution equation as shape function, fatigue residual strength, residual stiffness, and residual strain are calculated. The equivalent fatigue constitutive model is validated through comparison with experimental data, where satisfactory simulation results were obtained for axial compression and flexural tension fatigue. The model's novelty lies in integrating the fatigue damage evolution equation with CDPM, explicitly explaining performance degradation caused by fatigue damage. The proposed model could accommodate various forms of concrete constitution and fatigue stress states and has a broad application prospect for fatigue analysis of concrete structures. [ABSTRACT FROM AUTHOR]

Fiber-reinforced polymer (FRP) composites are promising materials already being used in bridge construction. Lightweight deck panels, mainly used in the rehabilitation or replacement of existing bridges, are the most commonly used FRP bridge components. However, FRP decks are prone to damage due to delamination, matrix cracking, interlaminar cracking, and debonding. In addition, due to their microstructure, FRP materials tend to deteriorate in ways that are not easily detected by visual inspection. Therefore, nondestructive methods should often complement visual inspections aimed at assessing the technical condition of the structure. New measurement techniques are constantly being researched and developed to assist in the evaluation of FRP structures. Distributed fiber optic sensing (DFOS) has been chosen as the main measurement technique of the newly developed FRP bridge deck panel because this technique provides extended advantages compared to the conventional spot gauges. The concept of a component with an integrated DFOS-based system capable of structural control and detection of overloaded vehicles has been developed and verified both in laboratory conditions. The novelty of the presented approach is that sensors (strain-sensing fibers) are precisely embedded in FRP laminates for simultaneous internal strain and vertical displacement (shape change) measurements and delamination detection. The experimental verification of a full-scale deck under static and dynamic loading is described in the paper. The performance of the DFOS system was verified using reference techniques. The results proved the system to be a reliable tool for diagnosing FRP bridge decks. [ABSTRACT FROM AUTHOR]

To investigate the nonlinear flutter characteristics of long-span suspension bridges under different deck ancillary structures and configurations, including those with and without a central wind-permeable zone, as well as to analyze the hysteresis phenomenon of a subcritical flutter and elucidate the mechanisms leading to the occurrence of nonlinear flutter, this paper studies first the post-flutter characteristics of the torsion single-degree-of-freedom (SDOF) test systems and vertical bending–torsion two-degree-of-freedom (2DOF) test systems under different aerodynamic shape conditions are further analyzed, and the role of the vertical vibration in coupled nonlinear flutter is discussed. The results indicate that better flutter performance is achieved in the absence of bridge deck auxiliary structures with a central wind-permeable zone. The participation of vertical vibrations in the post-flutter vibration increases with the increase in wind speed, reducing the flutter performance of the main girder. Furthermore, the hysteresis phenomenon in the subcritical flutter state is observed in the wind tunnel experiment, and its evolution law and mechanism are discussed from the perspective of amplitude-dependent damping. Finally, the vibration-generating mechanism of the limit oscillation ring is elaborated in terms of the evolution law of the post-flutter vibration damping. [ABSTRACT FROM AUTHOR]

Urban rail transit is rapidly evolving, with long-span cable-stayed bridges becoming increasingly popular among engineers because of their adaptability. However, as the operation time of bridges with tracks increases, the combined effects of repeated wheel loads and various bridge system excitations, including temperature changes and shrinkage–creep, gradually alter the alignment of the main beam. Similarly, the track structure on the bridge deck also undergoes vertical displacement, leading to corresponding degradation in rail alignment. This study applies singular function theory and verifies its effectiveness in bridge mechanical analysis. For the steel spring floating plate track cable-stayed bridge system, the mapping relationship between the deformation of the bridge’s main beam and the track’s deformation under bridge system excitation is derived, integrating singular function theory with the theory of train–track–bridge dynamic interaction. By analyzing the force transfer mechanism of the track–bridge system under system excitation, this research examines the effects of different excitations on the coupled dynamic response of the train–track–bridge. These findings suggest that system excitations increase the dynamic response of the train–track–bridge system, which is crucial for improving the durability and reliability of urban rail transit infrastructure. [ABSTRACT FROM AUTHOR]

The accurate prediction of the nonlinear flutter response is one of the important prerequisites for accurately evaluating the post-flutter performance of long-span bridges. In fact, as the vibration amplitude increases, the participation of lateral degree-of-freedom (DOF) will become more and more obvious and thus ignoring self-excited forces related to lateral vibration may no longer be applicable. To this end, based on 18 amplitude-dependent flutter derivatives (FDs), a 3-DOFs coupled nonlinear flutter analysis method was proposed in this study. Then, 18 amplitude-dependent FDs of two typical bridge decks were identified, and they were used to calculate the 3-DOF coupled nonlinear flutter responses based on the proposed flutter analysis method. Meanwhile, the correctness of the above flutter analysis method was also verified by compared with the numerical simulation results. Finally, the influence and mechanism of the lateral DOF, structural modal parameters and amplitude-dependent FDs on the nonlinear flutter of these typical bridge decks were investigated. The results show that when the torsional amplitude of the nonlinear flutter is large, the participation of lateral DOF will significantly increase the steady-state amplitude of the nonlinear flutter, and the larger the torsional amplitude, the more significant this increase is. The main reason is the participation of the lateral DOF introduces the negative coupled aerodynamic damping to the system, which then reduces the stability of the system. Besides, for the twin-box section, the influence of the lateral DOF on the nonlinear flutter is relatively smaller compared with the single-box section since the proportion of negative aerodynamic damping by the lateral DOF is smaller. Compared with the single-box section, the mass of the twin-box section has a smaller effect on the critical wind speed, and the torsional structural damping ratio of the twin-box section has a greater effect on the nonlinear flutter. [ABSTRACT FROM AUTHOR]

This paper presents the implementation of a novel monitoring system in which video images and conventional sensor network data are simultaneously analyzed to identify the structural flexibility from the ambient vibrations. The magnitude ratio between the flexibility estimated from known/unknown input force are theoretically derived and decomposed into two parts: αir$\alpha _i^r$ and Θk${{\Theta }_k}$. The first scale factor αir$\alpha _i^r$ related to basic modal parameters can be acquired using the general modal identification methods. Aiming to tackle the difficulty in identifying the second scale factor Θk${{\Theta }_k}$ related to the force intensity, a video stream of traffic is processed to detect and classify vehicles to determine the vehicle's location while displacement measurements are simultaneously collected. By integrating the toll station data, the vehicle loads are assigned to the vehicle on the bridge deck through the uniqueness of the license plate number. Thus, a structural input–output relationship is established to solve the second scale factor Θk${{\Theta }_k}$. Finally, the flexibility flex∼$\widetilde {flex}$ estimated from the ambient vibration are scaled by 1/αir$1/\alpha _i^r$ and 1/Θk$1/{{\Theta }_k}$, respectively to obtain the exact flexibility flex2$fle{{x}^2}$, which are same as the analytical ones flex$flex$. Both numerical example and a laboratory test are performed to demonstrate the accuracy of the proposed methodology. The algorithms, approaches, and results given in the paper demonstrate its effectiveness and shows great potential for its application on a real‐life bridge's condition assessment. [ABSTRACT FROM AUTHOR]

Bridges are crucial components of infrastructure networks that facilitate national connectivity and development. According to the National Bridge Inventory (NBI) and the Federal Highway Administration (FHWA), the cost to repair U.S. bridges was recently estimated at approximately USD 164 billion. Traditionally, bridge inspections are performed manually, which poses several challenges in terms of safety, efficiency, and accessibility. To address these issues, this research study introduces a method using Unmanned Aerial Systems (UASs) to help automate the inspection process. This methodology employs UASs to capture visual images of a concrete bridge deck, which are then analyzed using advanced machine learning techniques of Convolutional Neural Networks (CNNs) and Vision Transformers (ViTs) to detect damage and delamination. A case study on the Beyer Road Concrete Bridge in Michigan is used to demonstrate the developed methodology. The findings demonstrate that the ViT model outperforms the CNN in detecting bridge deck damage, with an accuracy of 97%, compared to 92% for the CNN. Additionally, the ViT model showed a precision of 96% and a recall of 97%, while the CNN model achieved a precision of 93% and a recall of 61%. This technology not only enhances the maintenance of bridges but also significantly reduces the risks associated with traditional inspection methods. [ABSTRACT FROM AUTHOR]

In order to reveal the influence of initial excitation on the bifurcation phenomenon of bridge decks, a new perspective of flow characteristics is developed based on the computational fluid dynamics numerical simulation method. Then, the bifurcation mechanism of vortex-induced vibration (VIV) response and nonlinear flutter response of the H-shaped section is investigated. The results show that when the wind speed is 2 m/s, under a small torsional excitation of 0.5°, the flow field of the H-shaped section will develop into the vortex shedding mode of the vertical vibration, resulting in vertical VIV. However, while under a large excitation of 6°, the flow field will directly transform into the vortex shedding mode of the torsional vibration, resulting in torsional VIV. Therefore, the bifurcation phenomenon of the VIV response is observed. When the wind speed is 4 m/s, the H-shaped section exhibits a nonlinear flutter limit cycle oscillation under a large excitation of 8°, but its response can be ignored under a small excitation of 0.5°. This phenomenon is attributed to the significant change in the transition of the vortex shedding mode from a small amplitude to a stable large amplitude, and the flow field lacks enough energy to complete the transition of the vortex shedding mode, resulting in the bifurcation phenomenon of the nonlinear flutter response. When the wind speed is 3.0 m/s, the large excitation will change the vortex shedding frequency of the new H-shaped section, resulting in the torsional VIV. [ABSTRACT FROM AUTHOR]

The higher efficiency of international transportation necessitates the introduction of combined transport systems. One of the most successful among these is train ferry transportation. And in order to provide safe transportation of wagons by sea, it is important to formulate the operational requirements for railway-sea transportation. And one of the loading modes for wagons is rolling on the train ferry. The article presents the results of determining the dynamic load of the open wagon body when rolling on the train ferry. The calculation was made for the open wagon placed on 18-100 bogies. A mathematical model was formed, which made it possible to determine the main dynamic indicators that characterize the movement of the wagon. The results of the calculations were used to determine the permissible inequality amplitude in the zone of interaction between the rail tracks of the bridge and the ferry deck so that the indicators of the car dynamics would be within the permissible values. The permissible value of the inequality amplitude was 0.021 m. The conducted studies will contribute to the database of developments on ensuring the operational safety of wagons used for international railway-sea transportation. [ABSTRACT FROM AUTHOR]

The study of railway dynamics remains an active and fertile field of research, given the technological evolution of this transport system. Several modeling methods have been developed to explore the dynamic interactions of a train-rail-bridge system, and these numerical models enable optimization of bridge design, especially for high-speed lines. In this perspective, this work joins this huge modeling project by proposing a procedure for assembling the elementary matrices of a dynamic system composed of a train, a rail and a bridge, in order to obtain the global differential equations of the system. The model studied consists of a moving part, the vehicle, modeled by a mass-spring-damper system, and a fixed part, the rail and bridge deck, modeled by two Bernoulli beams. The elements to be assembled are not identical, which increases the complexity of their assembly, as the position of the vehicle wheel changes as a function of time and passes from one element to another, creating loaded and unloaded elements. The dynamic equations were solved using the Newmark Beta numerical method. The model developed was subjected to a validation process based on a comparison of the dynamic responses of the bridge and vehicle obtained by the present study and those presented by previous studies. [ABSTRACT FROM AUTHOR]

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

A cable‐stayed footbridge for pedestrians and cyclists is situated in post‐industrial landscape Lover Vitkovice Area (DOV) of Ostrava. The bridge has two independent sections, 84,3 m and 68,3 m long that leads across the Ostravice river and the railway corridor directly towards the recent blast furnace. The bearing structure consists of outer lattice trusses and the lower steel orthotropic deck and is characterised by outstanding variable shape created by architect. The bridge's deck is supported by three and two pairs of cables, which run directly from top of the middle stiff pylon. Cables are connected to bottom chords of the structure by cylindrical fork with threaded rod and the tie rod structural system with rolled thread (turnbuckles, forks with pin and conical lock covers). The paper describes manufacturing, erection and pre‐stressing procedure, dynamic properties and design and installation of tuned mass dampers. [ABSTRACT FROM AUTHOR]

The increased traffic loads of the last decades led to an overload of the existing infrastructure. Especially for orthotropic steel decks of bridges, which are prone to fatigue fractures, this have led to structural damages of different categories. With respect to category 2 damages and their retrofit, this paper presents results of fatigue tests on the nonwelded constructional details of an old, demolished orthotropic steel deck. The samples were extracted from a highway bridge with an orthotropic steel deck built in Germany in the 1970s. In comparative fatigue tests on identical constructional details made of new material with the same steel grade, the remaining fatigue strength was determined. Based on the problem of manganese sulfides in old steels the potential of the repair method by cold joining techniques was emphasized. Characteristic load‐bearing capacities for a Eurocode 3‐compliant design of a structural blind fastener were determined and their use in a pilot project was reported. [ABSTRACT FROM AUTHOR]

This contribution describes the architectural and structural solutions of a unique pedestrian footbridge in Hradec Králové. The new significant construction was built over the Elbe River in the pedestrian area. The bridge design was challenging for architects, planners even though contractors, especially due to accounting for the influence of shipping traffic. Completed structure has two asymmetrical spans, whereas the main span across the river is 69 m long. In the final static scheme, the structure forms a virtual Vierendeel truss of variable height. A slender UHPFRC bridge deck supported by a pair of cables through thin steel crossbars creates a delightful bridge, which has become a new symbol of the city. [ABSTRACT FROM AUTHOR]

The new railway line connecting Luxembourg and Bettembourg crosses the A3 highway at a steep angle (19.5°) with the bridge called OA14. The designed bridge is a bowstring structure with a single span of 186.85 meters. The bridge deck consists of two lateral metal box girders acting as a chord. The deck is a transversal filler beam, with spherical voids and lightweight concrete to reduce the structure's weight. The bridge features two inward‐inclined arches at 9°, which are doubled and serve as trusses. This significantly increases the stiffness of the arch whilst keeping the silhouette elegant. The deck follows the curved track alignment, the arches remain straight. Two times 12 hangers connect the arches to the girders, they are made of CHS profiles of S450H quality. This article gives an overview of the structure and its construction. It then gives a more detailed insight in the design of the hangers, especially the hanger‐girder connections. [ABSTRACT FROM AUTHOR]

The primary challenge in the operation of steel deck pavement systems lies in the inspection and assessment of their condition. Traditionally, manual inspection methods are employed. However, these approaches are not only time-consuming and labor-intensive but also prone to human error. As a result, integrating data-driven machine learning technologies into the evaluation of pavement systems presents a significant advantage in addressing these issues. This study proposes a decision-making tool for estimating the condition levels of steel bridge deck pavement systems by employing classification techniques. To address the issue of class imbalance in the dataset, the SMOTE algorithm is utilized. Additionally, seven different machine learning methods—Light Gradient Boosting Machine, Extreme Gradient Boosting, Random Forest, Adaptive Boosting, K-Nearest Neighbor, Multilayer Perceptron, and Logistic Regression—are applied for training. Comparative analysis reveals that the Light Gradient Boosting performs optimally, achieving classification accuracies of 0.841 and 0.929 on the original and synthetic datasets, respectively. [ABSTRACT FROM AUTHOR]

As the bridge's structural component is directly subjected to vehicle loads, the stress performance of the bridge deck has a significant impact on the safety, durability, and driving comfort of the bridge. In order to improve the bending performance of the bridge deck in the negative moment zone, a new type of steel grating–UHPFRC composite bridge deck was proposed in this paper. Firstly, structural details and advantages of the new steel grating-UHPFRC composite bridge deck were introduced. Secondly, the finite element program ABAQUS was used to establish a refined solid finite element model of the new bridge deck. The mathematical program MATLAB (PYTHON) was also used to analyze the effects of the structural parameters on bending bearing capacity and put forward reasonable structural parameters of the new bridge deck, considering the technical and economic indexes. Thirdly, the simplified plasticity theory was applied to analyze the bending bearing capacity of the new bridge deck, and the corresponding formula for bending bearing capacity calculation was derived and verified by numerical model results. In addition, the cost–benefit analysis and environmental impact assessment of the new bridge deck were also conducted. The results show that the bending bearing capacity of the new bridge deck in the negative moment zone increases with the increase of the width of the bridge deck, the thickness of the wing plate, and the height of the web plate, with a trend of increasing and then decreasing when the horizontal inclination of the web plate decreases. The bridge deck width does not have a significant effect on improving the bearing capacity. The bearing capacity calculated by theoretical formulas is close to that calculated by numerical models and the maximum relative deviation is 9.1%. The new steel grating-UHPFRC composite bridge deck proposed in this paper is superior to conventional steel-UHPC composite bridge deck in terms of cost-benefit and environmental impact. [ABSTRACT FROM AUTHOR]

Orthotropic steel bridge decks (OSDs) play a key role in long-span bridges, and full-penetration welding technology is crucial to improve their structural performance. This study proposes an innovative single-sided full-penetration welding rib-to-deck (RTD) joint technology. The accuracy of the numerical simulation in predicting the temperature field and stress field was verified by the combination of an experimental and numerical simulation, and the welding residual stress (WRS) of single-sided full-penetration welded RTD joints was analyzed. In addition, the effects of different welding parameters and RTD joint geometry on the WRS are discussed. The results show that the experimental results are consistent with the simulation results, indicating that the single-sided full-penetration welding technology without a groove is feasible. The WRS shows a peak tensile stress near the weld, which gradually decreases and transforms into compressive stress as the distance increases. In addition, the WRS of the roof surface and the U-rib surface increases slightly with the increase in the roof thickness and the welding speed. The research results are of great significance to optimize the welding process, improve the fatigue performance, and prolong the service life of steel bridge decks, providing a new technical method for bridge engineering. [ABSTRACT FROM AUTHOR]

A novel prefabricated segmental guardrail is proposed to facilitate connections between guardrails and between guardrails and bridge decks by casting ultrahigh-performance concrete (UHPC) joints in situ. Through finite element crash simulation analysis of three types of vehicles and crash tests of real vehicles, the prefabricated segmental guardrail with a UHPC connection was systematically evaluated in terms of its energy-absorbing capacity, vehicular acceleration, post-impact trajectory of the impacting vehicle, and behaviour of the guardrail upon impact. During the evaluation process, performance comparisons of the prefabricated segmental guardrails are made with the monolithic concrete guardrails. The results indicate that the performance of the prefabricated segmental guardrail with a UHPC connection was superior to that of the conventional concrete monolithic guardrails: it exhibited a higher level of crash performance, the occupants of the impacting vehicle were better protected, and the impacting vehicle exhibited better post-collision stability. Finally, the convenience of the prefabricated segmental guardrails with UHPC connections was proven in practical engineering applications. [ABSTRACT FROM AUTHOR]

This paper presents a novel framework for assessing the impact of construction defects on bridge deck corrosion-induced deterioration. The model developed quantifies the impact of insufficient concrete cover, damage to the rebar epoxy coating, improper curing technique, and excessive water–cement ratio on the lifespan of concrete bridge decks. Regional variations, including freeze–thaw cycles, carbonation, and deicing salt usage, are also considered in the model. Two applications for estimating deterioration and decrease of condition rating are presented. Simulation results using the model developed reveal a substantial loss of life when these defects occur. This work highlights the importance of proper construction practices in ensuring long-term infrastructure integrity. Moreover, it provides a valuable tool for assessing the impact of these common construction defects on bridge deck deterioration. This tool enables bridge managers to make better-informed decisions regarding repair operations and ask contractors for fairer compensations when defective practices are observed during construction. [ABSTRACT FROM AUTHOR]

Cracks exist in many civil infrastructures, such as road and bridge deck surfaces, parking lots, and building surfaces. To prevent crack growth and further deterioration, it is necessary to fill these cracks with appropriate materials in a timely manner. To improve maintenance efficiency, many machines that automatically complete sealing work have been developed in construction and maintenance areas. However, most current path-planning algorithms used in machines are based on transverse and longitudinal cracks with relatively simple shape. This article presents a new path-planning algorithm for complex cracks that is used for automatic pavement crack-sealing systems. Information about the crack binary map is extracted from the actual crack image using our previous research work as a guide. Crack information is extracted and complex cracks are classified based on graph theory. The path-planning problem of connected cracks is then simplified to the Chinese Postman Problem, and the path-planning problem of unconnected cracks is simplified to the Rural Postman Problem. Finally, the feasibility of using the algorithm to deal with complex cracks is verified at the software level. The results indicate that the proposed algorithm has lower complexity and greater efficiency. [ABSTRACT FROM AUTHOR]

The durability of bridge deck pavement significantly influences the economic gains from bridge maintenance and transportation efficiency. With the increasing application of autonomous trucks (ATs) in highway bridges, there is a growing need to ascertain the adequacy of existing bridge deck pavement designed for human-driven vehicles to withstand the unique driving behaviors of ATs, especially their distinctive lateral driving behaviors, such as centering within lanes, which may affect the lifetime of bridge deck pavement. In this study, we first establish both the mechanical model and continuous variable temperature field model of the bridge deck pavement. Subsequently, a durability evaluation method is proposed for assessing rutting in bridge deck pavement that accounts for the lateral driving behavior of ATs. We examine the impact of varying lateral driving behaviors of ATs within a lane on the durability of bridge deck pavement with a double-layer structure. The findings show that the regulation of the lateral driving behavior of ATs can effectively postpone the onset of bridge deck pavement deterioration akin to rutting in human-driven trucks by up to 3.66 years (as determined by periodic detection year). This results in a notable reduction in rutting of 11% compared to human-driven trucks. Conversely, without the implementation of lateral control, the rutting caused by ATs could increase by 54%. Moreover, we develop and formulate lateral control strategies for ATs based on the theoretical insights obtained. These strategies take into consideration the applicable conditions for effective lateral control. This investigation not only provides essential theoretical support for maintenance and design strategies of bridge deck pavement within the realm of ATs but also offers operational recommendations for ATs on highway bridges. These suggestions encompass traffic speed limits and prescribed driving behaviors within lanes, which are essential considerations from the standpoint of AT operations. [ABSTRACT FROM AUTHOR]

Recognising the criticality of highway bridges for the socio-economic development of a nation, multiple researchers have endeavoured towards quantifying the seismic fragility of these key infrastructure elements. Given the present boom in urbanisation, however, there may also be an appreciable likelihood of vehicle presence on the highway bridge deck during an earthquake event. This study focuses on the impact assessment of vehicle-bridge-interaction (VBI) on the seismic fragility of highway bridges by explicitly accounting for vehicular movement atop the bridge deck during seismic shaking. Addressing existing drawbacks in literature that typically adopts a simplified modelling strategy and static vehicle placement, this paper considers different types of moving vehicles (modelled as mass-spring-dashpot system analogies) for VBI assessment through a novel algorithm. The proposed framework also accounts for uncertainties involved in the moving vehicle analysis, pertaining to vehicle characteristics and driver's perception of the earthquake. The framework is demonstrated on representative multi-span continuous steel girder bridges located in Central and Southeastern United States. A comparative assessment of hysteretic response of bridge components and seismic fragility curves indicate a considerable influence of vehicular movement on bridge damage, signifying the importance of considering moving VBI effects for thorough seismic assessment of highway bridge structures. [ABSTRACT FROM AUTHOR]

Wind tunnel tests or computational fluid dynamics (CFD) simulations of the aeroelastic model of a bridge deck section are currently used to make sure that significant vortex-induced vibration (VIV) of a long-span bridge will not occur after the bridge is put into operation. However, significant VIV still occurred in several long-span bridges in operation, indicating that the currently used wind tunnel tests and CFD simulations have some drawbacks or uncertainties. This study aims at establishing a digital twin by interacting CFD simulation with wind tunnel test for accurately and efficiently predicting the VIV response of a bridge deck. The measurement information of VIV of the deck section is collected from the wind tunnel test and fused with the CFD simulation. The optimisation for reducing uncertainties existing in wind tunnel test and CFD simulation is then carried out to make the CFD simulation as a digital twin. The digital twin is finally used to investigate the blockage effect of wind tunnel test and give an accurate and efficient prediction of VIV of the bridge deck. The flat closed-box steel deck section used in the Xiangshan Harbor cable-stayed bridge is selected as a case study. The results from the case study show that the digital twin can be established and used for an accurate and efficient prediction of VIV of the bridge deck section. [ABSTRACT FROM AUTHOR]

This study established a finite element model to assess the impact of various transverse strengthening techniques on the Xiuzhen River Bridge, a prestressed concrete box-girder bridge. On-site experiments validated the effectiveness of the finite element model. Five different strengthening techniques, namely, adding steel or concrete diaphragms (ASD or ACD), adding composite truss (ACT), strengthening bridge deck (SBD), and setting transverse prestress (STP), were compared. The results demonstrated a significant reduction in the deflection of the bridge using these techniques. SBD technology exhibited the highest deflection reduction rate at 47.91%, and STP technology achieved a maximum reduction rate of 53.92% in the presence of initial bridge damage. In addition, these techniques notably improved the lateral integrity from the load distribution factor (LDF). However, relying solely on the LDF cannot discern the most effective strengthening method. Therefore, a combined LDF and Kullback–Leibler divergence method was proposed to comprehensively analyse the relative entropy (RE) between different models. The results highlighted that SBD technology significantly reduced the RE of the bridge by 82.94%. In the presence of initial damage, ACT technology demonstrated significant stability in reducing the RE, with a sensitivity of only 10.98%. For newly constructed bridges, SBD technology is notably effective; however, for existing bridges, ACT technology may be a reasonable choice. Additionally, an investigation of failure modes emphasized that all the models exhibit similar failure modes, with initial damage and the implementation of different techniques primarily affecting cracking and ultimate load rather than significantly altering the overall failure mode. [ABSTRACT FROM AUTHOR]

This study explores the impact of corrosion on Ground Penetrating Radar (GPR) responses through practical experiments and numerical modelling, focusing on rebar diameter reduction, corrosion product layer thickness, crack formation and corrosion product filling in vertical and transverse crack. Practical experiments involved GPR testing of reinforced concrete slab. By analyzing B-scans we identify areas with moderate and severe corrosion. Numerical modelling using the Finite Difference Time Domain (FDTD) Method to model GPR signal propagation in a concrete bridge deck with corrosion is applied. Key finding includes a significant 26.70% increase in reflected wave amplitude when corrosion product filling in vertical crack increased by 400%, highlighting its extensive effect on signal GPR propagation. Reduced rebar diameter led to a 9.79% amplitude decrease and a 0.06 ns arrival time delay. Increased corrosion product layer thickness primarily affected arrival time with a 0.06 ns extension but significantly amplified GPR signal amplitude. These findings offer insights for improving GPR based corrosion detection and assessment methods, leading to more robust systems for concrete bridge deck inspection and maintenance. This paper contributes to understanding how corrosion affects the signal that is detected by GPR. This information can be used to improve the way that we manage and assess corrosion in concrete bridge deck. [ABSTRACT FROM AUTHOR]

Active flap is an advanced aerodynamic measure that can effectively increase the flutter performance of flexible bridges, but its control mechanism is still confusing due to the complex phenomenon of aerodynamic interference between the deck and flaps. This study proposes an assessment method to clarify the flutter control mechanism of the deck‐flap system by the computational fluid dynamics (CFD) method and quantifies the contribution of the aerodynamic damping from the active flaps. It is found that the composition of active flap to the improvement of flutter performance can be divided into torque effect and interference effect. Also, the torque effect of the flaps mainly provides equivalent positive aerodynamic damping ratio under effective control parameters, but the interference effects with the deck and two flaps are not the same, and the mutual interference effect between the two flaps is very weak. For the purpose of investigating the aerodynamic interference influence between the girder and flaps, the research further discussed the impact of the distance between the deck mounting position and the bridge girder on the system flutter performance. As the distance increases, the flutter performance of the system gradually improves. Also, the torque effect of the leading and trailing flaps will increase with distance. However, the interference effects of the flaps on both sides show different rules. In total aerodynamic damping ratio of the deck‐flap system, the torque effect accounts for about 70% and interference effect accounts for 30%. As the distance increases, the torque effect gradually becomes stronger and the interference effect gradually weakens. [ABSTRACT FROM AUTHOR]

Bridges are a crucial component of social infrastructure, playing a vital role in transportation, logistics and transit. Several bridges in South Korea were constructed during the rapid development period of the 1990s and 2000s, with RC slab bridges making up a significant portion of these structures. Over time, many of these bridges have aged considerably. To address this, the "Special Act on the Safety Control and Maintenance of Establishments" was enacted in South Korea to improve bridge maintenance. However, maintenance for aging small- to medium-sized bridges, except for Type 1 bridges, remains inadequate due to budget and personnel shortages. In this study, we developed a damage assessment method to evaluate the deterioration and analyze the current state of small- to medium-sized RC slab bridges. We derived the correlation between the deflection response ratio and the stiffness reduction rate of a bridge through structural analysis. This correlation data were then used to assess the damage to actual in-service bridges. Finally, we analyzed the current state of the target bridge and validated the damage assessment method. [ABSTRACT FROM AUTHOR]

Among infrastructure, concrete bridges are the most exposed to various environmental effects. Structural degradation occurs due to natural and artificial influences shortening the lifespan of the structure. Therefore, bridges need to be reinforced over time. The structures used in this study are re-formed using aged bridge floor decks that have been used for 50 years, approximately. The fiber-reinforced polymer (FRP) adhesion method, using sheets and plate forms, was selected among various reinforcement methods to investigate the performance of reinforced structures. We have tested various reinforcement scenarios including one and two layers FRP sheets and FRP plates. The mechanical properties of the reinforced structures were evaluated experimentally through tensile strength and flexural test experiments. In contrast to most available literature focused on model-based studies, our present work represents an experimental test validation of structural reinforcement on an actual bridge. Our results indicate that fiber-based reinforcement in sheet form exhibits higher performances of the reinforced structure compared to reinforcement using the plate form. This study is intended to provide sufficient data for reinforcing bridge floors that could be used for reference at future construction sites. [ABSTRACT FROM AUTHOR]

As a conductive material for snow melting on bridge decks, the interfacial shear strength of carbon fiber/rubber conductive composites is a prerequisite for engineering applications. The interfacial shear strength of the carbon fiber/rubber conductive composite was determined. The microstructure after the shear test was analyzed by scanning electron microscope (SEM). The interfacial stability was evaluated base on the extreme temperature on bridge decks. Finally, the interface durability was analyzed through 100 low-temperature cycles, 240 h high temperature and 50 electrification tests. The results show that the interfacial shear strength is 4.32 MPa. SEM results show that the shear force at the interface comes from three aspects. The interfacial shear strength is 13.45% higher than normal at −20°C, and 17.33% lower than normal at 60°C. The interfacial shear strength decreases by 7.48% after 15 cycles of low temperature and then stabilized. The effect of continuous high temperature and multiple energizations on the interfacial shear strength is small. SEM results confirm that low-temperature cycling reduces the internal bonding of rubber. The carbon fiber/rubber composite has good interfacial stability and durability. This study provides a mechanical foundation for the active snow melting of carbon fiber/rubber conductive composites on bridge decks. [ABSTRACT FROM AUTHOR]