Behavior Of Bridge Research Articles

Optimal replicator dynamic controller for semi active control of long span cable stayed bridge with considering special variability of seismic excitations

Cable-stayed bridges are lifeline infrastructures. However, due to their design and structural characteristics, they are sensitive to the vibrations. Thus, vibration control in these structures is essential. Semi-active control systems have gained significant attention due to their high performance and adaptability. However, the implementation of these systems has always faced serious challenges particularly when it comes to developing appropriate control algorithms because semi active devices have complex and non-linear characteristics. Inspired by evolutionary game theory, the author utilizes the replicator dynamic controller concept to optimize the performance of MR dampers to improve the vibration reduction of cable-stayed bridges. Two key parameters in the proposed control methodologies using replicator dynamics are the total population (total available resources or the sum of actuator forces) and the growth rate. Instead of using the sensitivity analysis that has been done in previous studies for vibration reduction of highway bridges using a replicator controller, the author used an evolutionary algorithm named the nondominated sorting genetic algorithm (NSGA-II) to create an optimal replicator dynamic controller for more effective vibration reduction. The proposed methodology is evaluated through its numerical application to a second-generation benchmark example based on the Bill Emerson Memorial Bridge, which considers a more realistic behavior of the cable-stayed bridge by accounting for multiple support excitations. The study indicates that the optimal replicator dynamic controller improves the vibration reduction performance of MR dampers. Specifically, deck displacement is reduced by 46 % compared to passive control system and shear forces at the tower base are reduced by 33 % compared to active control systems for the El Centro earthquake. The results indicate that the proposed Replicator Dynamic Controller optimized through NSGA-II provides a robust and effective solution for improving seismic resilience of cable-stayed bridges.

Dynamic Analysis of a Vehicle–Bridge System Under Excitation of Random Road Irregularities

This paper presents a comprehensive study of the dynamic response analysis of vehicle–bridge coupled systems, with detailed simulation methods for the vehicles, bridges, and wheel–road coupling relationships. The simulation of the entire vehicle–bridge coupling system is carried out using the open-source finite element analysis platform OpenSees. A novel three-dimensional wheel–road coupling element is introduced to model the interactions between the wheel and road nodes. This element facilitates precise computation of the dynamic responses within the vehicle–bridge coupled system, including both vehicle and bridge behaviors, along with the interaction forces between the wheels and the bridge surface. The coupling element consists of a wheel node and all potential road nodes on the bridge surface that the wheel may traverse. This configuration preserves the finite element model of the entire vehicle–bridge coupled system throughout the vehicle’s movement, thereby improving the efficiency of numerical simulations of vehicle–road interactions. The study accounts for the impact of random road irregularities on the dynamic responses of both the vehicle and the bridge. These irregularities are treated as input parameters for the wheel–road coupling element rather than being accounted for through the wheel–road interaction constraint equations, thereby improving the convenience of simulating random road irregularities.

Examining Multiculturals’ and Multilinguals’ Paradoxical Bridging Behaviors in Overcoming Cultural and Language Barriers in Organizations

Research has identified the usefulness of multicultural and multilingual employees in overcoming cultural and language barriers in international work contexts, but still needs to clarify why and how these employees engage in bridging behavior. Based on in-depth analyses of 154 interviews, we inductively develop a comprehensive model of bridging behaviors with novel and counterintuitive insights. We show that bridging behaviors are not only based on individual strengths, which multiculturals and multilinguals possess, but also—paradoxically—on their weaknesses. Multiculturals’ and multilinguals’ strengths and experience with weaknesses result in different determinants and enactments of bridging. Grounded in our inductive theory building, we propose four bridging behaviors: cultural teaching, language teaching, cultural facilitating, and language facilitating. Multiculturals and multilinguals cycle between these bridging behaviors depending on their capabilities and motivations in specific situations. We provide theoretical and practical implications of our findings.

Microreactor with coupled oscillatory flow: Research on liquid–solid two-phase characteristics and clogging mechanism

Dealing with multiphase systems containing solid particles in microreactor is a great challenge. Herein, microreactor with coupled oscillation technology was designed to explore clogging mechanism. The simulation revealed that no vortex was generated in the straight-tube microreactor. In the helical microreactor, the vortex could be generated and destroyed periodically. Second, the deposition clogging mechanism was explored. Solid particles were deposited and agglomerated without oscillation. After coupled oscillation, agglomerations were reduced, but deposition still existed in the straight microreactor. In the helical microreactor, the deposition phenomenon could be eliminated. Finally, the bridging clogging mechanism was explored. Solid particles were deposited first and then bridged without oscillation, forming a local high viscosity zone, and eventually completely clogging the reactor. After coupled oscillation, it was difficult to destroy the bridging behavior in the straight microreactor. In the helical microreactor, the periodic vortex could effectively destroy the bridging structure and the particles flowed uniformly.

Synthesis, Characterization, Biological Activity, Computational Evaluation and Molecular Docking Simulation of Dimeric Cu(II) Carboxylate Complexes

Copper(II) carboxylate complexes are important in biological fields. In this study, five new dinuclear Cu(II) complexes having the general formulae [Cu2(Cl-PAA)2(DMSO)2] (1), [Cu2(Cl-PAA)2(phen)2] (2), [Cu2(Cl-PAA)2(bipy)2] (3), [Cu2(Cl-PAA)2(py)2] (4), [Cu2(Cl-PAA)2(Cl-Py)2] (5) were synthesized and characterized by FTIR and UV-Vis spectrophotometry. FTIR study supported the monodentate nature of the carboxylate in complexes 2 and 3 while bidentate bridging behavior of carboxylate was observed in complexes 1, 4 and 5. UV-Vis study revealed the presence of d-d transition in visible region, while charge transfer band was observed in ultraviolet region. Antimicrobial activities of complexes 1-5 were studied among which complexes 1, 2 and 4 showed good activities. The results of antioxidant assay demonstrated that free radical scavenging activity by Cu(II) complex containing 1,10-phenanthroline was higher compared to other complexes. All the synthesized complexes were optimized by DFT-D-based DMol3 module in Material Studio. After that, the quantum chemical parameters containing hardness, softness, and electrophilicity were calculated. Based on value of (ω), complex 2 showed the best biological activity that supported experimental studies. All complexes were investigated by molecular docking with cytochrome P450 14 alpha-sterol demethylase (1ea1), the docking findings demonstrated that complex 2 had the highest interaction with cytochrome P450 due to the biggest interaction energy of complex 2 as compared with other complexes. In addition, according to corrosion studies, complex 2 showed highest coating on the iron (110) surface protecting the iron from corrosion due to high adsorption value.

Mechanism based four-linear cohesive zone model for mode I fracture of different stacking sequence CFRP laminates

Delamination, a prevalent failure mode observed in laminated composites, exerts a significant impact on structural integrity and performance. The occurrence of fiber bridging during the fracture process adds complexity and elevates the research challenges associated with this phenomenon. Existing models exhibit limitations in accurately capturing bridging behavior and discerning its underlying mechanical mechanisms. This study addresses these limitations by analyzing experimental results, employing the J-integral, and analyzing R-curve behavior, proposing a mechanism-based four-linear cohesive zone model along with a new finite element implementation method. Comprising three overlapping bi-linear CZMs, this model effectively simulates mode I fracture behavior in laminates with different stacking sequences. Moreover, it intuitively illustrates the mechanical mechanisms during crack propagation and offers simplicity in implementation. This research contributes to a deeper understanding of composite fracture mechanics and provides a practical model for predicting delamination behavior in laminated structures.

A Review of the Mechanical Properties of and Long-Term Behavior Research on Box Girder Bridges with Corrugated Steel Webs

Based on an analysis of the extant literature, this paper summarizes the research progress on the mechanical properties and long-term behavior of corrugated steel web (CSW) box girder bridges. First, the research results of CSW box girder bridges in terms of the shear buckling performance (local shear buckling, overall shear buckling, and interaction buckling), bending performance, bending capacity, torsional capacity, and coefficient of internal force increase are summarized, along with the main factors affecting the mechanical performance of CSW box girder bridges. Second, based on research on the self-oscillation characteristics and dynamic response of CSW box girder bridges, the influence of structural parameters on the self-oscillation characteristics is analyzed. Finally, the long-term mechanical behavior of the CSW box girder bridges is analyzed in terms of fatigue, creep, and temperature effects. The existing research results demonstrate that there still exist deficiencies in the mechanical properties and long-term behavior of CSW box girder bridges, and this paper thus suggests a future research focus on CSW box girder bridges to provide a reference for further improving their basic theoretical system.

Mode II fracture behavior of glass fiber composite-steel bonded interface–experiments and CZM

The dominant failure mode was characterized as debonding in the novel non-welded wrapped composite joint made with GFRP composites wrapped around steel sections. Glass fiber composite-steel three-point end notched flexure (3ENF) and four-point end notched flexure (4ENF) specimens were utilized to experimentally investigate mode II fracture behavior of this composite-steel bonded interface. Two new methods were proposed with the help of digital image correlation (DIC) technique to quantify fracture data during the tests: 1) the “shear strain scaling method” to quantify the crack length a; 2) the asymptotic analysis method based on the longitudinal displacement distribution along the height of the specimen at the pre-crack tip to quantify the crack tip opening displacement (CTOD). To numerically simulate the mode II fracture behavior, a four-linear traction-separation law was proposed in the cohesive zone modeling (CZM) where the softening behavior with a plateau was defined by the authors between traditionally considered initiation and fiber bridging behavior. The experimental and numerical approaches were validated mutually through good matches between the test and FEA results. 3ENF test provided good insight into softening behavior while 4ENF contributed to quantification of fiber bridging. These findings contribute to a more comprehensive characterization and understanding of the ductile fracture behavior of bi-material bonded joints, especially in mode II failure scenarios.

Experimental Study on the Bending Behavior of Precast Concrete Segmental Bridges with Continuous Rebars at Joints

Longitudinal ordinary rebars are discontinuous at the joints of precast concrete segmental bridges (PCSBs), which can open under tensile stresses induced by bending moments. This will lead to durability issues with the joints. To improve the bending properties of PCSBs, a novel joint type featuring continuous rebars was proposed in the present study. Three specimens were subjected to testing to examine the bending behavior of PCSBs using this new joint design compared to traditional joints. The crack propagation, structural deformation, joint opening width, strain in rebars, failure mode, stiffness, and flexural capacity were comprehensively investigated. The test results reveal that the continuous rebars effectively transferred bending normal stress between joints, ensuring full development of cracks in each beam segment. Effective control of joint opening width was also observed. Compared to traditional joints, the new joints exhibited a 29% to 33% increase in cracking load and a 32% increase in ultimate load. Failure in the continuous rebar joints was characterized by partial anchorage failure of the rebars along with localized concrete crushing in the top compression zone. Based on the test results, a computational method was proposed for calculating the cracking strength and flexural capacity of the new joints.

Bridging Behavior of Palm Fiber in Cementitious Composite

This study addresses the growing need for sustainable construction materials by investigating the mechanical properties and behavior of palm fiber-reinforced cementitious composite (FRCC), a potential eco-friendly alternative to synthetic fiber reinforcements. Despite the promise of natural fibers in enhancing the mechanical performance of composites, challenges remain in optimizing fiber distribution, fiber–composite bonding mechanism, and its balance to matrix strength. To address these challenges, this study conducted extensive experimental programs using palm fiber as reinforcement, focusing on understanding the fiber–matrix interaction, determining the pullout load–slip relationship, and modeling fiber bridging behavior. The experimental program included density calculations and scanning electron microscope (SEM) analysis to examine the surface morphology and diameter of the fibers. Single fiber pullout tests were performed under varying conditions to assess the pullout load, slip behavior, and failure modes of the palm fiber, and a relationship between the pullout load and slip with the embedded length of the palm fiber was constructed. A trilinear model was developed to describe the pullout load–slip behavior of single fibers, and a corresponding palm-FRCC bridging model was constructed using the results from these tests. Section analysis was conducted to assess the adaptability of the modeled bridging law calculations, and the analysis result of the bending moment–curvature relationship shows a good agreement with the experimental results obtained from the four-point bending test of palm-FRCC. These findings demonstrate the potential of palm fibers in improving the mechanical performance of FRCC and contribute to the broader understanding of natural fiber reinforcement in cementitious composites.

Investigation of seismic response amplification effects of diverse multi-support earthquake excitations on cable-stayed bridges

This study addresses the critical need to understand the seismic behavior of cable-stayed bridges under Multi-Support Excitation (MSE) in order to mitigate earthquake-induced damage to these structures. The primary focus is on the investigation of response amplification phenomena and their seismic implications for cable-stayed bridges. Through a detailed comparative analysis of MSE and Synchronous Excitation (SE) across various structural locations, the study evaluates the impact of site-specific recorded ground motions of different earthquake categories. A pragmatic framework is developed to simulate realistic MSE ground motions for diverse earthquake scenarios, emphasizing the necessity of considering MSE in bridge design. The findings reveal a significant amplification of the design requirements due to antisymmetric mode excitation and increased tower and pier motions. The study also identified the need for in-depth analysis of cable-stayed bridges to address the increased vulnerability of tower-adjacent areas and to devise targeted reinforcement strategies of vulnerable components. These insights are critical for advancing seismic design practices and improving the resilience of cable-stayed bridges, contributing to safer urban infrastructure.

Effect of Damping on the Identification of Bridge Properties Using Vehicle Scanning Methods.

Vehicle scanning methods are gaining popularity because of their ability to identify modal properties of several bridges with only one instrumentation setup, and several methods have been proposed in the last decade. In the numerical models used to develop and validate such methods, bridge damping is often overlooked, and its impact on the efficacy of vehicle scanning methods remains unknown. The present article addresses this knowledge gap by systematically investigating the effects of bridge damping on the efficacy of vehicle scanning methods in identifying the modal properties of bridges. For this, acceleration responses obtained from a numerical model of a bridge and vehicle are used. Four different scenarios are considered where vehicle damping, presence of road roughness, and traffic on the bridge are varied. Bridge damping is modeled using mass-proportional, stiffness-proportional, and Rayleigh damping models. The impacts of ignoring bridge damping or considering one of these damping models on the modal frequencies and mode shapes identified using the vehicle response are investigated by comparing the results. The outcomes of the numerical analysis show that ignoring bridge damping in vehicle scanning applications can significantly increase the efficacy of these methods. They also show that the identifiability of the bridge frequencies and bridge mode shapes from the vehicle response decreases significantly when bridge damping is considered. Further, the damping model used impacts which bridge modes can be identified because different damping models provide different modal damping ratios for each mode. The results highlight the importance of correctly simulating damping behavior of bridges, which is often ignored, to be able to correctly evaluate the efficacy of vehicle scanning methods, and they provide an important stepping stone for future studies in this field.

DYNAMIC BEHAVIOUR AND DAMPING OF STEEL RAILWAY BRIDGES AT A SPEED OF 200 KM/H

AbstractThe subject of the paper is the comprehensive information on experiments carried out on a group of railway bridges near Břeclav, Vranovice and Soběslav, covering filler beams, steel girder bridges and composite bridges. The subject was to determine the behavior of bridges at higher speeds and to determine the value of damping as a basis for the preparation of HSR lines in the Czech Republic.This paper describes the structures investigated and recapitulates selected findings, particularly related to the damping. Also, the general findings from a number of tests focusing on damping are also given.

Experimental and Numerical Analysis of an Innovative Combined String–Cable Bridge

Suspension bridges, such as stress-ribbon, are among the simplest structural bridge systems and have the lowest structural height. The flexibility of these elegant bridges poses great challenges for designers to minimize their deformability under asymmetrical operational loads. Due to the small initial sag, such load-bearing structures also cause significant tensile forces, which requires them to have large cross-sections and massive anchor foundations. This paper analyzes an innovative suspension steel bridge structure combined with a string and a cable. More attention is paid to asymmetric loading as this is more relevant for suspension structures. The new structure is studied numerically and experimentally. It is established that the string stabilizes the displacements of the bridge under asymmetric loading. The stabilization efficiency is proportional to the value of the pre-tension force of the string. The obtained results reveal the behavior of the structure and enable an evaluation of the accuracy of the numerical results, as well as the applied modeling. In addition, the experimentally obtained results allow the evaluation of more aspects of the behavior of the new bridge, which will be useful in further studies of this type of structures.

Dynamic behaviors of bridge with corroded RC piers under barge collisions

Reinforced concrete (RC) bridge piers located in navigable waterways are susceptible to chloride-induced corrosion, which may cause severe damage or even entire collapse of bridge under potential barge collisions. The present study aims to examine the failure patterns and dynamic responses of typical simply supported girder bridge with corroded RC piers under barge collisions. Firstly, nine RC column specimens with three designed corrosion degrees and two corrosion strategies were prepared using the impressed anodic current technique. Secondly, the drop hammer impact and axial compression tests were successively performed to examine the residual axial load bearing capacities of both unimpacted and impacted specimens. Furthermore, by comprehensively considering the effects of corrosion-induced deteriorations on the effective cross-sectional area and yield strength of reinforcements, concrete strength, as well as the rebar-concrete bond-slip relationship, the refined finite element (FE) models of specimens were established and validated. Finally, the dynamic behaviors of a prototype simply supported girder bridge with corroded RC piers under barge collisions at different service lives, i.e., 0–60 years, were numerically assessed. It indicates that: (i) under drop hammer impact, six specimens all exhibit global flexure failure, and relatively severe concrete cracking and spalling occur in the specimens with 15 % designed corrosion degree; (ii) the axial load bearing capacities of specimens with 5 % and 15 % designed corrosion degrees are reduced by 15.46 % and 34.86 % compared to the unimpacted non-corroded specimen, and 11.29 % and 43.30 % compared to the impacted non-corroded specimen; (iii) the transverse impact resulted in 25.93 %, 22.27 % and 35.53 % reductions in axial load bearing capacities for 0 %, 5 % and 15 % designed corrosion degree, respectively; (iv) for the prototype barge-bridge collision scenario, the failure patterns vary from minor bending cracks to remarkable flexural failure as the service live increases from 0 to 60 years. The corrosion-induced degradations of bridge performance should be concerned for the vessel collision-resistant design of bridge.

Over 25-year monitoring of the Tsing Ma suspension bridge in Hong Kong

AbstractBridges in service are subjected to environmental and load actions, but their status and conditions are typically unknown. Health monitoring systems have been installed on long-span bridges to monitor their loads and the associated responses in real time. Since 1997, the Tsing Ma suspension bridge in Hong Kong has been the world’s first of the type equipped with a long-term health monitoring system. For the first time, this study reports the first-hand field monitoring data of the bridge from 1997 to 2022. The 26-year data provide an invaluable and rare opportunity to examine the long-term characteristics of the loads, bridge responses, and their relationships, thereby enabling the assessment of the bridge’s load evolution and structural condition over time. Results show that traffic loads have remained stable after 2007, highway vehicles kept increasing until the COVID-19 pandemic in 2020, the annual maximum deck temperature continued to increase at a rate of 0.51 °C/decade, typhoon durations increased by 2.5 h/year, and monsoon speeds decreased and became dispersed and variable. For the bridge responses, deck displacement is governed by the varying temperature. Natural frequencies in the past 26 years were almost unchanged. The overall condition of the bridge is very satisfactory. Current status and recent update of the health monitoring system are also reported. Lastly, prospects of bridge health monitoring are discussed. This study is the first to report the over one-quarter century status of a structural health monitoring system and the behavior of a long-span suspension bridge. This research provides a benchmark for many other bridge monitoring systems worldwide.

Behavior of steel box girder bridges under blast loads and the possibility of reopening the bridge immediately following the explosion

Behavior of steel box girder bridges under blast loads and the possibility of reopening the bridge immediately following the explosion

Analytical Linearization of Aerodynamic Loads in Unsteady Vortex-Lattice Method for Nonlinear Aeroelastic Applications

This paper presents the analytical linearization of aerodynamic loads (computed with the unsteady vortex-lattice method), which is formulated as tangent matrices with respect to the kinematic states of the aerodynamic grid. The loads and their linearization are then mapped to a nonlinear structural model by means of radial-basis functions, allowing for a two-way strong interaction scheme. The structural model comprises geometrically exact beams formulated in a director-based total Lagrangian description, circumventing the need for rotational degrees of freedom. The structural model is spatially discretized into finite elements and temporally discretized with the help of an implicit scheme that identically preserves momenta and energy. The resulting nonlinear discrete equations are solved by applying Newton’s method, requiring calculating the Jacobians of the whole aeroelastic system. The correctness of the linearized loads is then shown by direct comparison with their numerical counterparts. In addition, we employ our strongly coupled aeroelastic model to investigate the nonlinear static and dynamic behavior of a suspension bridge. With this approach, we successfully investigate the numerical features of the aeroelastic system under divergence and flutter conditions.

Research on spatial corrosion behavior and durability protection technology of concrete box girder bridge in cold regions

In order to study the corrosion behavior of concrete box girder in deicing salt environment, a series scaled model of concrete box girders were made to study the deterioration mode of concrete box girder under load, chloride corrosion, freeze-thaw cycle and their combined action. Combined with silane impregnation, the durability protection technology of concrete box girder bridges in cold regions was proposed. The experimental results show that under freezing-thawing action, the top plate of the box girder has the most serious deterioration, and the performance of the web is better. The surface erosion of the top plate is 65.38 % and 80.77 % different from that of the bottom plate and web plate, respectively. The freezing-thawing erosion of the concrete box girder has a significant spatial multi-dimension. The chloride ion erosion law of the top plate and bottom plate of concrete box girder is similar to the distribution law of shear lag effect under load. The inhibition effect of compressive stress on chloride ion is 9.67 %, and the overall inhibition effect is not large. The maximum difference of chloride ion concentration at each measuring point on the bottom plate is 30.14 %. Silane can be used as a protective coating for concrete bridges in cold areas, and the coating thickness of 2 mm can meet the requirements of anti-freezing. With the increase of freeze-thaw time, the silane protection ability began to decline. The maximum silane protection effect of 0–1 cm from the surface at 90d and 180d decreased by 40.8 % and 71.7 %, respectively. After the silane coating was applied, the chloride ion erosion rate of the bottom plate still showed a faster trend. When the freeze-thaw cycle exceeded 30 times, the silane protection ability decreased almost at a linear rate with the freeze-thaw time. Regardless of whether the silane coating protection technology is adopted, the chloride ion concentration of the bottom plate of concrete box girders is at least 10 % more than that of the top plate for freeze-thawing 90d and 180d, and the maximum can reach 32.1 %. The deterioration behavior of concrete box girders in cold regions has significant spatial multi-dimension. The existing single-parameter durability design methods, which mainly focus on solid section, are no longer suitable for box girder structures.

Probabilistic ductile deformation limit state prediction of monolithic exterior shear keys based on quantile regression machine learning techniques

Shear strength and ductile deformation capacity of monolithic exterior shear keys play important roles on the seismic behavior of highway bridges. Improving the ductility of the shear key through reasonable design could effectively restrict superstructure displacement and minimize damage to pier columns. However, most existing studies primarily focus on evaluating the shear strength and damage mechanisms of shear keys, with limited attention given to analytical models for assessing ductile deformation capacity. To this end, this study proposes a method that combines quantile regression and machine learning techniques to predict the ductile deformation limit states of shear keys. The proposed numerical modeling method for shear keys is validated using the experimental data on lateral load-displacement curves. On this basis, Latin hypercubic sampling and joint simulation are utilized to establish the ductile deformation limit state database. The ductile deformation limit states of shear keys are characterized by their lateral displacements in three distinct damage states. The main influencing factors of each limit states are investigated by correlation analysis. Three quantile regression machine learning models are trained and constructed to conduct point and interval prediction for the ductile deformation limit states. All three models, particularly the Gaussian process quantile regression model, are proven to demonstrate exceptional prediction accuracy and uncertainty quantification. Experimental data validation confirms that these models outperform the prediction accuracy of existing simplified models.