Bridge Research Articles

Investigation of Retrofit Strategies to Extend the Service Life of Bridge Structures through Active Control

Investigation of Retrofit Strategies to Extend the Service Life of Bridge Structures through Active Control

Local Full-Scale Model Test on Mechanical Performance of the Integral Splicing Composite Structure of Adjacent Existing Box Girder Bridges

Local Full-Scale Model Test on Mechanical Performance of the Integral Splicing Composite Structure of Adjacent Existing Box Girder Bridges

System under Seismic Loadings and Seismic Response of Curve Bridge with Frictional Pendulum System under Multidimensional Seismic Excitation

The earthquake exhibits significant abruptness and extensive destruction, while the bridge is crucial for linking the transportation hub pre- and post-earthquake. Ensuring the bridge's seismic resilience is vital for minimizing casualties and property damage, as well as facilitating rescue operations. This study examines the impact of multidimensional seismic excitation on the seismic performance of a curved bridge utilizing a friction pendulum. A finite element model of a four-span curved simply supported beam girder is developed using Sap2000. Seismic excitation artificially manufactured with MATLAB. The analysis focuses on the influence of the seismic wave's characteristic period and the friction coefficient of the friction pendulum on the seismic response of vibration-isolated bridges, employing the nonlinear time-distance method. The findings indicate that the characteristic period of seismic waves exerts varying effects on distinct locations of the bridge structure, with vertical seismic waves significantly impacting the seismic response of the abutment structure, the maximum rate of change exceeds 40%. Furthermore, as the friction coefficient escalates, the varying dimensions of seismic waves increasingly affect different locations of the bridge structure, while the seismic response of the abutment follows a consistent pattern of change, the minimal value is achieved at a friction factor of 0.07.

An Improved Gaussian Mixture Model-Based Data Normalization Method for Removing Environmental Effects on Damage Detection of Structures

In structural health monitoring, effectively eliminating the influence of variable environmental conditions on modal frequencies remains a critical challenge for accurate damage identification. Nonstationary and nonlinear variations in modal frequencies, commonly induced by environmental changes, tend to overshadow the effects caused by structural damage. An improved Gaussian mixture model (GMM) is proposed in this paper to normalize nonlinear and nonstationary frequency data, enabling effective structural damage detection under variable environmental conditions. As the effectiveness of the GMM is highly influenced by the initial parameter values used in the expectation-maximization (EM) algorithm, a subdomain division strategy is first presented to determine the unique initial values of the GMM parameters. Through the application of the EM algorithm, the GMM is constructed simply and efficiently through the determined initial parameters. Next, on the basis of the constructed GMM, the modal frequency data are normalized to extract damage features that remain unaffected by environmental variations. Subsequently, Hotelling’s T2 statistic and its cumulative form are calculated for the damage features and designated as the damage indicators; meanwhile, the corresponding damage thresholds are also calculated according to the kernel density estimation technique. To validate the proposed method, two case studies are conducted: one with a numerical mass-spring system and the other with a real bridge structure. Results show that environmental influences no longer impact the normalized frequency data, and the cumulative statistic demonstrates outstanding accuracy in identifying structural damage.

Influence of the Objective Function in the Dynamic Model Updating of Girder Bridge Structures

Influence of the Objective Function in the Dynamic Model Updating of Girder Bridge Structures

Continuously Reinforced Concrete Pavement Terminal Design

In rigid pavement design the word “terminal” is used to describe the termination of a concrete pavement abutting other “structures” such as a flexible pavement, a bridge abutment, or another concrete pavement where structural continuity is impractical or undesirable. A discontinuity in grade caused by the differential settlement between a bridge structure and the adjoining road pavement, typically referred to by the travelling public as the “bump at the end of a bridge”, is well known in the road construction environment. In the United States it is known that this problem affected 25% (approximately 150,000) of all bridges during 2004. Bridge approach slabs are typically used to keep the effects of differential settlement at bridge abutments within tolerable limits. Frequently, however, the magnitude of settlement exceeds the working range of an approach slab, causing substantial maintenance problems. Similarly, differential settlement or movement often occurs where a concrete pavement terminates at a flexible pavement. The provision of anchors (lugs) to prevent horizontal creep due to expansion / contraction of the concrete is considered standard practice in terminal design. The aim of this paper is to compare various worldwide continuously reinforced concrete pavement (CRCP) terminal design methods varying from terminal beams to seamless technology developed to eliminate isolation joints at bridge structures.

Adaptive Sensor Placement Selection and Response Reconstruction for Bridge Structural Health Monitoring

Abstract Bridge structural health monitoring (SHM) measures the real-time responses of bridges via instrumented sensors. This paper focuses on the bridge displacement reconstruction at unmeasured locations of interest (LoIs) using measurements from sensors. Increasing the number of sensors on the bridge can capture more structural information. However, considering the complex structure and scale of bridges, minimizing the number of sensors and selecting the critical sensing locations (CSL) to place sensors for measurements are significant in bridge SHM. To achieve efficient bridge SHM under limited number of sensors, this paper proposes an adaptive sensor selection and reconstruction neural network (ASSRNN) for determining the CSLs and reconstructing at all LoIs. In particular, a novel adaptive location selection mechanism (ALSM) as well as a unified network model and its learning process is proposed. In the experiments, the proposed model is validated based on a real-world case study of a long-span bridge in California, USA. Through the comparison of different sensor placement schemes. The experimental results show that the proposed model is effective and accurate in reconstructing the structural displacement responses via adaptive sensor selection for bridge SHM.

Multi-pathway oxidative stress amplification via controllably targeted nanomaterials for photoimmunotherapy of tumors

Photoimmunotherapy, which combines phototherapy with immunotherapy, exhibits significantly improved therapeutic effects compared with mono-treatment regimens. However, its use is associated with drawbacks, such as insufficient reactive oxygen species (ROS) production and uneven photosensitizer distribution. To address these issues, we developed a controllable, targeted nanosystem that enhances oxidative stress through multiple pathways, achieving synergistic photothermal, photodynamic, and immunotherapy effects for tumor treatment. These nanoparticles (D/I@HST NPs) accurately target overexpressed transferrin receptors (TfRs) on the surface of tumor cells through surface-modified transferrin (Tf). After endocytosis, D/I@HST NPs generate ROS under 808-nm laser irradiation, breaking the ROS-responsive crosslinking agent and increasing drug release and utilization. Tf also carries Fe3+, which is reduced to Fe2+ by iron reductase in the acidic tumor microenvironment (TME). Consequently, the endoperoxide bridge structure in dihydroartemisinin is cleaved, causing additional ROS generation. Furthermore, the released IR-780 exerts both photodynamic and photothermal effects, enhancing tumor cell death. This multi-pathway oxidative stress amplification and photothermal effect can trigger immunogenic cell death in tumors, promoting the release of relevant antigens and damage-associated molecular patterns, thereby increasing dendritic cell maturation and sensitivity of tumor cells to immunotherapy. Mature dendritic cells transmit signals to T cells, increasing T cells infiltration and activation, facilitating tumor growth inhibition and the suppression of lung metastasis. Furthermore, the myeloid-derived suppressor cells in the tumor decreases significantly after treatment. In summary, this multi-pathway oxidative stress-amplified targeted nanosystem effectively inhibits tumors, reverses the immunosuppressive tumor microenvironment, and provides new insights into tumor immunotherapy combined with phototherapy.

Surface Morphology and Remaining Geometric Parameters of Corroded Members on Bailey Truss

Abstract Bailey truss has been widely used in temporary constructional structures of bridges, and is reusable. In the service duration, Bailey truss is commonly exposed to corrosion threats due to the failure of anti-corrosion coatings, resulting in corrosion damage on members which induces degradation of its structural behavior. This paper presents an investigation on the corrosion damage of a Bailey truss which had been in service for eight years in the Northeast China. A total of 18 member segments were obtained from the chords, diagonals, and verticals of the Bailey truss, and were scanned by a 3D laser scanner after clearing the paint and rust. Then reverse modeling was performed based on the 3D coordinates of the specimen surfaces. The surface topography was discussed for different members on the basis of the separated roughness component, the residual thickness was analyzed for plates, and the residual cross-sectional area and moment of inertia about axes of the members were calculated and discussed. Coupon tests were carried out on corroded specimens from chords, diagonals, and verticals to quantitatively analyze the degradation of corroded Bailey truss. It was found that the corrosion damage on flanges was more severe than that on webs, in terms of the surface roughness and thickness loss. The corrosion status can be influenced by the microstructures and serving location. Upon the true values of the remaining cross-sections, it was concluded that the chords, diagonals, and verticals of the Bailey truss all exhibited the largest loss ratio in moment of inertia about y axis and the smallest loss ratio in cross-sectional area. The vertical member had the largest dispersion of average nominal loss rates, especially for moment of inertia about y axis, whose maximum and minimum values differed by 157.1%. A practical method for estimating the residual cross-sectional area and moment of inertia was validated. In addition, the engineering mechanical parameters (the elastic modulus, yield strength, ultimate strength, and the elongation after fracture) of each member basically show linear degradation. The mechanical parameters of diagonal web are most affected by corrosion. There is 10% thickness loss in chord web with up to 27% loss bearing capability in 8 years, and the factor of safety with respect to a reference parameter is lowered.

Mathematical modeling of occlusion load on a screw-retained bridge prosthesis on straight universal conical and flat abutments

In this mathematical experiment, a comparative study of microdeformations and von Mises equivalent stresses arising in the elements of two orthopedic bridge structures with different abutment shapes was conducted using the finite element method. The strength limits of both structures were also compared. The structures under study had the same external geometry and corresponded to two premolars and the first molar. The difference between the models under study was in the superstructures that are inserted and fixed in the implants and serve as a support for artificial crowns. The first model used flat superstructures (or flat abutments), while the second model used conical superstructures (or universal multi-units). The data obtained indicate the clinical significance of choosing the optimal abutment shape when planning surgical interventions and predicting subsequent patient treatment results.

A Fast Identification Method for Seismic Responses of Bridge Structures by Integrating Digital Signal Features and Deep Learning.

A method of bridge structure seismic response identification combining signal processing technology and deep learning technology is proposed. The short-time energy method is used to intelligently extract the non-smooth segments in the sensor acquired signals, and the short-time Fourier transform, continuous wavelet transform, and Meier frequency cestrum coefficients are used to analyze the spectrum of the non-smooth segments of the response of the bridge structure, and the response feature matrix is extracted and used to classify sequences or images in the LSTM network and the Resnet50 network. The results show that the signal processing techniques can effectively extract the structural response features and reduce the overfitting phenomenon of neural networks, and the combination of signal processing techniques and deep learning techniques can recognize the seismic response of bridge structures with high accuracy and efficiency.

Wireless Accelerometer Architecture for Bridge SHM: From Sensor Design to System Deployment

This paper introduces a framework to perform operational modal analysis (OMA) for structural health monitoring (SHM) by presenting the development and validation of a low-power, solar-powered wireless sensor network (WSN) tailored for bridge structures. The system integrates accelerometers and temperature sensors for dynamic structural assessment, all interconnected through the energy-efficient message queuing telemetry transport (MQTT) messaging protocol. Moreover, it delves into the details of sensor selection, calibration, and the design considerations necessary to address the unique challenges associated with bridge structures. Special attention is given to the solar-powered aspect, allowing for extended deployment periods without the need for frequent maintenance or battery replacements. To validate the proposed system, a comprehensive field deployment was conducted on an actual bridge structure. The collected data were transmitted through MQTT messages and analyzed by means of OMA. Comparative studies with traditional wired systems underscore the advantages of the solar-powered wireless solution in terms of sustainability, scalability, and ease of deployment. Results from the validation phase demonstrate the system’s capability to provide accurate and real-time data needed to assess the health state of the monitored asset. This paper concludes with insights into the practical implications of adopting such a solar-powered WSN, emphasizing its potential to revolutionize bridge health monitoring by offering a cost-effective and energy-efficient solution for long-term infrastructure resilience.

Load Testing Application for Truss Bridge Design Verification: Live Load Testing

This is the second of two companion papers discussing application of load testing techniques for verification of bridge design. The bridge was a six-spans continuous steel truss structure, about 338-m long and 14.45-m wide, in the State of New York. Design of the bridge was completed using an unconventional approach where the top chords of the main trusses, floor beams, and stringers were designed to act composite with the concrete deck. In addition to axial forces, such a design also gives rise to secondary moments in the truss main members under design loads. This aroused interest in verification of the design through an instrumentation, monitoring, and load testing program. Comparing the members’ actual service load axial forces and moments with those used in the design, it was concluded that axial forces were overestimated in the design by about 20 percent for service dead load and by about 25 percent for service live load. Similar comparison for moments, indicated that service dead load moments were within 20 percent of those used in the design and service live load moments were underestimated by about 55 percent. The above differences for service dead load can be attributed to the way the deck pours were accounted for in the design and the possibility of construction loads being on the structure during the deck pour monitoring. For service live load, these differences can be explained by possible discrepancies in estimating service live load from the test results and the fact that the analysis for service live load in the design was performed ignoring the contribution of the composite concrete deck. Adequacy of the structural design under actual axial forces and moments was confirmed by checking the AASHTO interaction equations for steel members under combined axial and bending loading conditions. The major contribution of this and the companion paper is that, they introduced a new approach for estimating total dead load effects by only monitoring strains in a limited number of truss members during staged deck construction and load testing of a very large truss bridge structure, it validated the unconventional design under both dead load and live load as a viable method for design of truss bridge structures, and it supplemented the very limited literature on dead load monitoring of bridges.

Load Testing Application for Truss Bridge Design Verification: Dead Load Monitoring

This is the first of two papers discussing application of load testing techniques for verification of bridge design. The bridge was a truss structure in the State of New York, which atypical to conventional design, the top chords of the main trusses, floor beams, and stringers were designed to act composite with the concrete deck. Under load, in addition to axial forces, such a design creates secondary moments in the truss main members and complicates the analysis. This inspired the need for verification of the bridge design through an instrumentation, monitoring, and load testing program. The objective of this paper is to verify dead load design. Achieving this objective required instrumentation of main members of the erected structure and monitoring of strains in those members during concrete deck construction. For total dead load, a pseudo analytical approach was used to incorporate load effects due to self-weight of the structure. Five members of the downstream truss were instrumented with vibrating wire gages to record strains in those members during the first three deck pours. Finite element (FE) and deck monitoring results were utilized in the pseudo analytical approach to investigate actual axial forces and moments due to service total dead loads. The investigation indicated that those forces and moments were within 20 percent of those estimated based on FE analysis during the bridge design. The way the deck pours were accounted for in the design and presence of construction loads on the deck during the monitoring might have contributed to this difference. The paper’s major contribution is that it introduced a new approach for estimating total dead load effects by only monitoring strains in a limited number of truss members during staged deck construction, it validated the unconventional design as a viable method for design of truss bridge structures, and it supplemented the very limited literature on dead load monitoring of bridges.

Biotechnology for Global Sustainability: Innovations, Applications, and Challenges

Biotechnology, from a global perspective, involves applying biological systems, organisms, or derivatives to develop innovative products and processes that address global challenges and enhance the quality of life. As an interdisciplinary field bridging biology, technology, and engineering, biotechnology significantly impacts critical sectors, including healthcare, agriculture, environmental management, and industrial processes. In healthcare, biotechnology drives advancements in vaccines, gene therapy, personalized medicine, and diagnostic tools, improving disease prevention and treatment. Agricultural biotechnology focuses on developing genetically modified (GM) crops with higher yields, resistance to pests, and adaptability to climate change, ensuring food security. Additionally, it enhances livestock breeding and productivity. Environmental applications of biotechnology include bioremediation to combat pollution, development of biofuels to reduce reliance on fossil fuels, and creation of biodegradable materials to mitigate waste. In industrial processes, biotechnology optimizes manufacturing efficiency through the use of enzymes and microorganisms, contributing to sustainable production. Globally, biotechnology addresses pressing challenges like food insecurity, climate change, health inequality, and environmental degradation. Its role in sustainable development is critical, fostering eco-friendly solutions and improving the resilience of economies and societies. However, the field raises ethical and regulatory concerns, such as the risks of genetic engineering and the equitable distribution of benefits. International collaboration among governments, industries, and scientists is essential to ensure responsible innovation and maximize biotechnology’s potential to improve global well-being. As a transformative science, biotechnology continues to shape the future, balancing innovation with sustainability and equity.

Generalization of anomaly detection in bridge structures using a vibration‐based Siamese convolutional neural network

Generalization of anomaly detection in bridge structures using a vibration‐based Siamese convolutional neural network

Study on the mechanical behavior of corroded bridge steel based on the entire process of tensile failure

Abstract The Q345qD bridge steels exposed to severe corrosion environments undergo mechanical property degradation, posing significant safety risks for sea-crossing bridges. Assessing the health of corroded bridge steel structures under load conditions in a manner that avoids causing damage can effectively prevent these intensifying safety hazards. To investigate the impact of corrosion on the mechanical performance of these steels, six sets of standard specimens underwent corrosion ranging from 0 to 896 h. Subsequently, during tensile testing, an image acquisition platform was established to utilize Digital Image Correlation (DIC) techniques for capturing and observing the tensile loading processes of various corroded specimens. Analysis of stress–strain curves and strain field evolution patterns provided insights into the deterioration of mechanical properties of Q345qD bridge steels after corrosion. For corroded bridge steel structures, defects caused by the corrosion pits can still result in localized strain concentration under low load levels. At higher load levels, mass loss due to corrosion or reduced cross-sectional dimensions of load-bearing elements are the primary causes of mechanical performance decline, precipitating overall structural failure. These findings provide some references for routine maintenance of steel structures of cross-sea bridges.

Application of dynamic vibration dampers for vibration protection of bridge structures

Introduction. The increase in traffic intensity and the prospects for the development of high-speed railway transport require solving the problem of the effectiveness of vibration protection of transport infrastructure facilities by developing innovative solutions. Currently, the issues of combating vibration in relation to the span structures of bridges and overpasses are insufficiently studied. The purpose of the work is to study the promising directions of vibration protection of bridge structures based on the use of dynamic vibration dampers.Research methodology. To achieve the goal of research and implementation of effective technical solutions in the field of vibration protection of bridge structuresimproved design of dynamic vibration damper is proposed in which inertial mass is fixed on two springs, upper of which is connected to structure protected from vibration, and lower spring to base or foundation of object. Oscillations are damped due to oscillations in antiphase due to free and forced oscillations of auxiliary inertial masses protected from vibrations. This technical solution makes it possible to balance forces of elastic interaction of damping device and object protected against vibration and moments from these forces.Results. As a result of experimental studies of the prototype of the improved dynamic vibration damper installed on the vibration stand, it was found that the vibration levels in all directions significantly decreased, including in the vertical direction by 5.7 times.Discussion and conclusion. The obtained positive results of experiments and the relative simplicity of the proposed design make it possible to propose this method of vibration protection of superstructures for both newly designed and already in operation facilities. It is especially important to minimize the possibility of resonant phenomena and pitching. The results of the study will make it possible in the future to ensure the effectiveness of vibration protection of oscillating machines, mechanisms and infrastructure facilities.

Recommendations for Active-Learning Kriging Reliability Analysis of Bridge Structures

Recommendations for Active-Learning Kriging Reliability Analysis of Bridge Structures

Microstructure Regulation and Fabrication of Epoxy-based Conductive Films with Excellent Electrical and Thermal Conductivity, Adhesion, Toughness, and Flexibility

The electrically conductive adhesive films (ECAFs) are new materials used for large-format bonding in microelectronics packaging. However, improving its electrical and thermal conductivity, adhesion, and flexibility simultaneously has been a challenge. In this study, silver powder with different particle sizes and poly(3,4-ethylenedioxythiophene)/poly(styrene sulfonate) (PEDOT/PSS) were used to create a high-efficient multi-scale conductive bridge structure. This reduced the volume resistivity from 7.30×10-4 Ω·cm to 3.80×10-4 Ω·cm, with lower silver powder content. The thermal conductivity improved from 9.074 W/m·K to 9.124 W/m·K, and adhesion performance between the epoxy matrix and the metal increased from 6.85 MPa to 8.08 MPa. Furthermore, the addition of hydroxyl-functionalized polyurethane materials enhanced the toughness without significantly affecting its electrical, thermal, and adhesion properties. This study successfully prepared epoxy-based conductive adhesive films with a combination of electrical conductivity, thermal conductivity, adhesion, and flexibility, while significantly reducing costs due to the reduction in silver powder content.