Stability Of Bridge Research Articles

Time-domain state-space model formulation of motion-induced aerodynamic forces on bridge decks

Motion-induced aerodynamic forces play a fundamental role in the stability and buffeting analysis of long-span bridges, which are traditionally performed in the frequency domain adopting the well-known approach based on flutter derivatives and aerodynamic admittance functions. However, the increase in span of newly designed bridges currently raises concerns regarding the role of nonlinear aerodynamic effects, the response to non-stationary winds and the aerodynamic coupling in multi-modal vibrations. Addressing these issues requires to calculate aerodynamic forces induced by arbitrary motions and, possibly, consider large variations in the incoming flow orientation, a task better suited for time-domain approaches. In this study, we introduce a time-domain state-space model formulation for motion-induced aerodynamic forces, which systematizes and generalizes previous models, while keeping a simple structure and ease of calibration. We tailor the model formulation to allow for a clear distinction between quasi-static and purely transient aerodynamic contributions and investigate the relations between the proposed model and other available models, highlighting their common underlying framework. The model is finally calibrated for a selection of bridge decks, showing a very good ability to reproduce motion-induced aerodynamic forces.

Capillary Skimming of Floating Microplastics via a Water-Bridged Ratchet.

Floating microplastics (MPs) have recently become a major concern in marine pollution; however, current filter-based technology is hardly effective for directly removing such MPs from the water surface because of specific mesh size and clogging issues. This paper introduces a new skimming concept for removing floating MPs utilizing capillary force mediated by the elevation of a hydrophilic ratchet at the air-water interface. MPs floating near the ratchet surface are spontaneously forced toward the ratchet with a concave water meniscus, driven by the Cheerios effect. The MPs can then be skimmed and temporarily held by the deforming concave water meniscus as the ratchet rises. Here, it is found that the stability of the water bridge plays a crucial role in skimming success because it provides capillary adhesion between the MP and the ratchet. The proposed capillary skimming method is observed to be effective across nearly all types of floating MPs, ranging in size from 1 to 4 mm, and with densities varying from 0.02 to 0.97 gcm- 3, which is also demonstrated by a prototype of marine robot cleaner.

Bridge Structural Design Simulation: Case Study of Nongsa Pura Bridge

The influence of various components, including the deck, girders, trusses, cables, and other structural elements, plays a significant role in determining the long-term stability and service life of bridges. With the increasing demands of traffic loads, environmental factors, and material degradation, it is crucial to reassess and enhance the existing calculations for bridge superstructure designs. This paper aims to redesign and reanalyze the superstructure of the Nongsa Pura Bridge by using secondary data for calculations. The results of this study include updated design specifications, specifically WF 500x200x10x16 and WF 800x300x14x22 structural profiles. The research methodology involves a detailed re-evaluation of the bridge's structural elements, focusing on adapting to contemporary standards and ensuring the bridge’s resilience to evolving demands.

Total Synthesis of Talarolide A and atrop-Talarolide A: Hydroxamate H-Bond Bridge Stabilization of Cyclic Peptide Conformers Invokes Non-Canonical Atropisomerism.

The first total synthesis of the Australian marine tunicate fungus-derived cyclic peptide talarolide A (1) has confirmed the structure previously proposed on the basis of spectroscopic and chemical analyses and re-affirmed the importance of the unique hydroxamate H-bond bridge in ring conformer stabilization. The unexpected co-synthesis of atrop-talarolide A (8) revealed, for the first time, that hydroxamate H-bond bridging in the talarolide framework invokes non-canonical atropisomerism and that talarolides A (1), C (3), and D (4) all exist naturally as atropisomers. These discoveries raise the intriguing prospect that comparable functionalisation of other cyclic peptides, including those with commercial value, could provide ready access to new "unnatural atropisomeric" chemical space, with new and/or improved chemical and biological properties.

An Investigation into the Impact of Time-Varying Non-Conservative Loads on the Seismic Stability of Concrete-Filled Steel-Tube Arch Bridges

When the arch rib of the mid-bearing through and lower-bearing through arch bridges undergoes out-of-plane deformation, it is usually subject to the resilience force provided by the flexible hanger, which is known as the “non-conservative force effect” of the suspender. In contrast to the static condition, in the dynamic scenario, the time-varying non-conservative force exerted by the flexible suspender becomes more complex due to dynamic changes in external load. Moreover, the difference in fundamental frequency and vibration period between the bridge system and arch rib may influence the stress distribution within the arch rib during ground motion. This paper investigates the impact of time-varying non-conservative forces on the dynamic stability of arch ribs in concrete-filled steel tube (CFST) bridges under seismic loads. Specifically, it examines the influence of different seismic waveforms, frequency disparities between bridge slabs and arch ribs, and suspender stiffness on the non-conservative effect. The results reveal significant disparities in the impact of non-conservative forces exerted by the suspender during seismic events with identical intensity but varying frequency characteristics. The influence of non-conservative forces on the dynamic stability of bridges escalates as deck stiffness increases, while it remains relatively unaffected by changes in suspender stiffness.

A Study on the Influence of Wood’s Roughness on the Stability of Wooden Arch Bridges

A Study on the Influence of Wood’s Roughness on the Stability of Wooden Arch Bridges

Stability or Instability of a Static Liquid Bridge Appearing in Shaped Crystal Growth from Melt via the Pulling-Down Method

Abstract: This study presents sufficient conditions for the stability or instability of the static liquid bridge appearing in crystal growth from the melt of micro-fibers, thin plates, and hollow micro-tubes of predetermined sizes using the pulling-down method [...]

Three-Dimensional Reconstruction and Visualization of Underwater Bridge Piers Using Sonar Imaging.

The quality of underwater bridge piers significantly impacts bridge safety and long-term usability. To address limitations in conventional inspection methods, this paper presents a sonar-based technique for the three-dimensional (3D) reconstruction and visualization of underwater bridge piers. Advanced MS1000 scanning sonar is employed to detect and image bridge piers. Automated image preprocessing, including filtering, denoising, binarization, filling, and morphological operations, introduces an enhanced wavelet denoising method to accurately extract the foundation contour coordinates of bridge piers from sonar images. Using these coordinates, along with undamaged pier dimensions and sonar distances, a model-driven approach for a 3D pier reconstruction algorithm is developed. This algorithm leverages multiple sonar data points to reconstruct damaged piers through multiplication. The Visualization Toolkit (VTK) and surface contour methodology are utilized for 3D visualization, enabling interactive manipulation for enhanced observation and analysis. Experimental results indicate a relative error of 13.56% for the hole volume and 10.65% for the spalling volume, demonstrating accurate replication of bridge pier defect volumes by the reconstructed models. Experimental validation confirms the method's accuracy and effectiveness in reconstructing underwater bridge piers in three dimensions, providing robust support for safety assessments and contributing significantly to bridge stability and long-term safety assurance.

Lyapunov stability of suspension bridges in turbulent flow

In the era of sleek, super slender suspension bridges, facing the issue of stability against dynamic wind actions represents an increasingly complex challenge. Despite the significant progress over the last decades, the impact of atmospheric turbulence on bridge stability remains partially not understood, evoking the need for innovative research approaches. This study aims to address a gap in current research by investigating the random flutter stability associated with variations in the angle of attack due to turbulence, which has not formally been addressed yet. The present investigation employs the 2D rational function approximation model to express self-excited forces in a turbulent flow. The application of this type of models to bridge dynamics yields a viscoelastic coupled dynamic system characterized by memory effects and driven by broad-band long-time-scale noise, described here by a linear homogeneous time-variant differential equation, which shows apparent nonlinear features, and which has rarely been matter of research. Utilizing a Monte Carlo methodology, this work innovates in applying the largest Lyapunov exponent (LE) and the moment Lyapunov exponents (MLE) to study bridge random flutter stability. The calculation of LE and MLE under diverse turbulent wind conditions uncovers lower flutter stability than without turbulence effects. In most cases, sample and low-order p-th moment stability thresholds closely align with the bridge dynamic response pattern; therefore, the flutter critical wind speed is unequivocal. However, under certain turbulence scenarios, it is necessary to resort to MLE for a complete description of stability, evoking some additional consideration of which statistical moments should be considered for the engineering assessment of the flutter limit. Finally, this work provides a qualitative insight into the instability mechanisms by approximating the random parametric excitation with a sinusoidal gust and evaluating the time-periodic system stability via Floquet theory.

A Failure Analysis of the Long-Term Overturning Stability of Concrete Continuous Single-Column Pier Bridges Considering Creep and Overloaded Vehicles

Several single-column pier girder bridges have been involved in overturning accidents, resulting in significant economic losses and casualties, thus necessitating a risk assessment of the overturning stability. To date, the effect of structural degradation due to concrete creep on the long-term stability of bridges has not been demonstrated. In this study, a full-scale nonlinear analysis of the lateral overturning process of a collapsed concrete box girder based on the explicit dynamic finite element method (EFEM) was conducted to verify the reliability of the numerical method. An EFEM model incorporating concrete creep was developed to demonstrate the effect of structural degradation on the long-term stability of bridges. The synthesis overturning axis method (SOAM) was proposed to evaluate the long-term overturning stability of concrete continuous bridges, aiming to address the deficiencies in existing methods, particularly for curved bridges, and was compared with conventional methods. The results show that the variations in bearing reaction forces between curved and straight bridges under creep and self-weight are minimal, staying within 2%. An increase in the creep terminal coefficient results in the opposite trend in the ultimate vehicle weight of curved bridges and straight bridges, but fluctuations remain within 2%, indicating that long-term creep has a limited effect on the overall overturning stability. A failure analysis of 20 single-column pier bridges reveals significant differences in the ultimate vehicle weight between the rigid overturning axis method (ROAM) and folded overturning axis method (FOAM), with error ranges of −14.2% to 567.4% and −99.1% to −32.1%, respectively. The SOAM results have the smallest error range compared to those of the EFEM, with an error range of −38.8% to 33.9%. Despite these errors, the SOAM demonstrates a significant improvement in characterizing the trend and assessment accuracy of the overall overturning stability of single-column pier bridges.

Improving the identification of dynamic parameters of bridges by UAV: approach for SHM

The structural integrity of bridges is susceptible to deterioration caused by traffic loads, environmental conditions, and weather phenomena. To maintain the safety and stability of bridges, regular inspections of their elements are required. Recent advances in the field of unmanned aerial vehicles (UAVs) provide a viable option for accurate and autonomous inspections of bridge structures without disrupting normal operations. This study focuses on the determination of the dynamic structural parameters of a suspension bridge. The methodology focuses on determining the natural vibration frequency of the bridge cables using UAV imagery. This paper contains a detailed theoretical presentation of the algorithm used, accompanied by a careful analysis of simulation results and empirical data from laboratory experiments and real case studies. In addition to the image processing-based approach for estimating the vibration frequency, the sensors on board the drone are also scrutinized and their effectiveness in detecting structural vibrations after the drone lands on the bridge surface is evaluated.

Failure Analysis for Overall Overturning of Concrete Single-Column Pier Bridges Induced by Temperature and Overloaded Vehicles.

Several overloaded-induced overturning incidents of girder bridges with single-column piers have occurred in recent years, resulting in significant casualties and economic losses. Temperature, in addition to overloading, may also play a role in exacerbating bridge overturning. To investigate the association between temperature and bridge overturning, an explicit finite element model (EFEM) of a three-span concrete curved continuous bridge considering nonlinearities was developed to simulate overall collapse. The effects of uniform and gradient temperatures on the overall overturning stability of curved and straight bridges were evaluated based on the EFEMs. Furthermore, the temperature-bridge coupling model and temperature-vehicle-bridge coupling model were utilized to examine how gradient temperature influences bridge overturning. The results show that the overall overturning collapse of a bridge follows four stages: stabilization, transition, risk and overturning. Variations in uniform temperature from -30 °C to 60 °C had a negligible effect on the ultimate vehicle weight for bridge overturning, with a variation of less than 1%. As the gradient temperature ranged from -30 °C to 60 °C, curved bridges show less than a 2% variation in ultimate vehicle weights, compared to a range of -6.1% to 11.7% for straight bridges. The torsion caused by positive gradient temperature in curved bridges can exacerbate bridge overturning, while negative gradient temperature in straight bridges can lead the girder to 'upward warping', facilitating girder separation from bearings. Monitoring the girder rotation angle and vertical reaction force of bearings can serve as important indicators for comparing the stability of bridges.

Analysis of Vibration Characteristics of Bridge Structures under Seismic Excitation.

Bridges may undergo structural vibration responses when exposed to seismic waves. An analysis of structural vibration characteristics is essential for evaluating the safety and stability of a bridge. In this paper, a signal time-frequency feature extraction method (NTFT-ESVD) integrating standard time-frequency transformation, singular value decomposition, and information entropy is proposed to analyze the vibration characteristics of structures under seismic excitation. First, the experiment simulates the response signal of the structure when exposed to seismic waves. The results of the time-frequency analysis indicate a maximum relative error of only 1% in frequency detection, and the maximum relative errors in amplitude and time parameters are 5.9% and 6%, respectively. These simulation results demonstrate the reliability of the NTFT-ESVD method in extracting the time-frequency characteristics of the signal and its suitability for analyzing the seismic response of the structure. Then, a real seismic wave event of the Su-Tong Yangtze River Bridge during the Hengchun earthquake in Taiwan (2006) is analyzed. The results show that the seismic waves only have a short-term impact on the bridge, with the maximum amplitude of the vibration response no greater than 1 cm, and the maximum vibration frequency no greater than 0.2 Hz in the three-dimensional direction, indicating that the earthquake in Hengchun will not have any serious impact on the stability and security of the Su-Tong Yangtze River Bridge. Additionally, the reliability of determining the arrival time of seismic waves by extracting the time-frequency information from structural vibration response signals is validated by comparing it with results from seismic stations (SSE/WHN/QZN) at similar epicenter distances published by the USGS. The results of the case study show that the combination of dynamic GNSS monitoring technology and time-frequency analysis can be used to analyze the impact of seismic waves on the bridge, which is of great help to the manager in assessing structural seismic damage.

Feasibility of Using Green Laser for Underwater Infrastructure Monitoring: Case Studies in South Florida

Scour around bridges present a severe threat to the stability of railroad and highway bridges. Scour needs to be monitored to prevent the bridges from becoming damaged. This research studies the feasibility of using green laser for monitoring the scour around candidate railroad and highway bridges. The laboratory experiments that provided the basis for using green laser for underwater mapping are also discussed. The results of the laboratory and field experiments demonstrate the feasibility of using green laser for underwater infrastructure monitoring with limitations on the turbidity of water that affects the penetrability of the laser. This method can be used for scour monitoring around offshore structures in shallow water as well as corrosion monitoring of bridges.

Stability of Beam Bridges Under Bridge-Vehicle Interaction

In this paper, we provide an accurate and reliable formulation for simulating the interactions of both train/bridge subsystems and suitable for high-speed railway lines as well as for existing lines worldwide that are being renewed or modernized. We model the train as a series of suspended masses, taking into account the energy dissipation and the suspension system for each train vehicle. On the other hand, the bridge supporting the rails with irregular elevations will be modeled as an Euler-Bernoulli beam. The mathematical formulation of the interaction problem between the two subsystems requires the writing of two sets of equations, which interact with each other through contact forces. Using a one-dimensional finite element formulation, a series of equations are constructed by Modeling the beam structure. In addition, the suspended mass equations are first discretized using Newmark's finite difference formulas, which then reduce the degrees of freedom (DOF) of the vehicle to those of the bridge element. This solves the coupling problem between the two subsystems. The derived component is known as the vehicle/bridge interaction (VBI) element. On the other hand, an iterative procedure will be used subsequently to solve the non-linearity problem of the resulting system of differential equations. MATLAB programs provide results that identify the critical parameters influencing the bridge's dynamic stability.

Research on Simulation and Evaluation of Environmental Adaptability of Ribbon Bridge Based on GMRES Algorithm

This paper focuses on the safety of ribbon bridge navigation at different flow speeds, including bow tilt and stern tilt. By constructing a CAD 3 dimensions simulation model and CFD simulation test model of a ribbon bridge, the Hydrodynamics of the ribbon bridge under different load conditions and flow velocity is simulated and calculated based on the GMRES algorithm.The environmental adaptability assessment was carried out from the aspects of bow tilt, stern tilt and flow velocity adaptability of the ribbon bridge, and the navigation safety and stability of the ribbon bridge in different environments were obtained, which could provide data reference and support for the safe navigation of the ribbon bridge in the actual waters.

Research on Common Diseases and Construction Treatment Technologies in Road and Bridge Engineering

Road and bridges are the most basic transportation infrastructure. Its construction quality and use of safety are directly related to the lives of the people and the stability of society. In the process of construction and use, road and bridge projects often face challenges of multiple diseases. Such as uneven settlement, steel bar corrosion and breakage, and cracks. These diseases not only affect the safety and stability of roads and bridges, but also threaten people's driving safety and smooth traffic. This article mainly analyzes the common disease problems in road and bridge projects and propose reasonable measures in a targeted manner, aiming to improve the quality of roads and bridges and reduce the chance of the diseases of roads and bridges.

An Analytical Study of Suspension Bridge Collapse Based on the Characteristics of the Eigen Values

This research discusses an analytical approach to suspension bridge accidents focusing on eigenvalue characteristics. This research uses eigenvalue analysis to explore patterns that may contribute to bridge structural failure. The analysis steps include reducing the model to an uncoupled and linear system, as well as determining homogeneous and non-homogeneous solutions, which helps identify accident-prone patterns. The analysis results also reveal significant differences in dynamic characteristics between safe bridges and those that experience accidents. This research highlights the importance of a deep understanding of eigenvalues in designing, maintaining, and managing suspension bridges. The implication of this research is the development of more effective prevention strategies to improve suspension bridge safety in the future. By analyzing eigenvalues, this research provides deep insight into the factors that influence the stability of suspension bridges. These findings provide a strong foundation for developing recommendations for more effective design, maintenance, and management of suspension bridges. The conclusions of this research can help improve the safety and reliability of suspension bridges worldwide and contribute to civil engineering and infrastructure security.

Stability analysis of long-span bridge under static wind load

With the maturity of various technologies and the vigorous development of advanced materials, the design and construction of suspension bridges require larger spans and lighter structures, but at the same time, the problems arising from the dynamic and static responses of the system under wind loads have become more and more prominent. The phenomenon of wind-induced static response occurring before the emotional response has been found in wind tunnel tests at home and abroad. Static instability is also a vital issue in the wind-resistant design of large-span suspension bridges, so studying the static behavior and instability law of large-span suspension bridges under strong winds is of high practical value for the construction of large-span bridges in the future. In this paper, relevant research results of previous researchers based on static wind stability of suspension bridges are sorted out and summarized. Their corresponding fundamental theories are introduced in detail. In addition, the related analysis program is prepared by using the APDL language of ANSYS.

Formation of cation bridges and its promoting mechanism for sorption of sulfamethoxazole by montmorillonite

The coexistence of metal cations is often accompanied by organic pollution and could affect the environmental fate of organics by mediating the formation of cation bridges. However, the environmental fate and risk of organics in cation co-existing environments are poorly understood due to the lack of accurate identification of cation bridge formation and stability. In this study, the sorption of sulfamethoxazole (SMX) on montmorillonite (MT) with the coexistence of three different valence metal cations (Na+, Ca2+, and Cr3+) was investigated. Ca2+ and Cr3+ can significantly promote the sorption of SMX on MT for about 5∼10 times promotion, respectively, while Na+ bridges displayed little effect on the sorption of SMX. The sorption binding energy of SMX with MT-Ca (−44.01 kcal/mol) and MT-Cr (−64.57 kcal/mol) bridges was significantly lower than that with MT-Na (−38.45 kcal/mol) and MT (−39.39 kcal/mol), indicating that the sorption affinity of SMX on Cr and Ca bridges was much stronger. The higher valence of the cations also resulted in a more stable adsorbed SMX with less desorption fluctuation. In addition, the relatively higher initial concentration of SMX and the valence of cations increased the bonding density of the cation bridges, thus promoting the apparent sorption of SMX on MT to a certain extent. This work reveals the formation and function of cation bridges in the sorption of SMX on MT. It lays a theoretical foundation for further understanding the environmental fate and risk of organics.