Hasil untuk "Bridge engineering"

WANG Chao, ZOU Jinfeng, , SHU Dan, WU Qinhua

In order to investigate the safe construction distance of shield tunnel crossing the pile foundation of the existing bridges, taking the crossing construction at the orthogonal side as an example and considering the influences of the pile shear effects, we use the Pasternak two-parameter foundation model to establish the equilibrium differential equations for the horizontal displacements of the soil in the middle of the pile foundation of the existing bridges and the tunnels under construction, and the analytical solutions for the horizontal displacements of the pile-tunnel intermediate soil are derived. Based on the cusp catastrophe theory, the standard expression for the potential function of the pile-tunnel intermediate soil and the sufficient and necessary conditions for its system to be suddenly destabilized are determined. Accordingly, the method for calculating the critical safe distance of the pile foundation of the existing bridges is established, and its engineering applicability is verified through the numerical simulations and field measurements. The method is used to analyze the main influencing factors for the critical safe distance of the pile foundation of an existing bridge. The results show that the critical safe distance is approximately an exponential function with the diameter ratio of the pile foundation of the bridge, and the two parameters are positively correlated, while it follows a quadratic function of the shield tunnel depth ratio, and first increasing and then decreasing as the depth ratio increases, and reaches the maximum value when the depth ratio of the shield tunnel is 8.1. The theoretical values obtained by the proposed method and the estimated ones by the numerical simulation are well fitted, and the measured results and the relevant specifications also further verify the engineering applicability of this method. The proposed method provides theoretical guidance for the rational development of the design and construction program of similar tunnel crossing projects.

Gang Li, Wei Xiao, Yanlin Liang et al.

In foundation pit engineering, precise determination of the physical–mechanical parameters of the surrounding rock is essential for reliable simulation of rock deformation and anchor cable forces. A foundation pit engineering project in Shapingba District, Chongqing, was selected as a case study. A numerical model was developed using FLAC3D, and 64 working conditions were designed via orthogonal experiments to serve as training samples. Global optimization inversion of the samples was performed using a BP neural network enhanced by particle swarm optimization. Using selected monitoring data of surrounding rock displacement and anchor cable forces, inversion was conducted to determine the physical–mechanical parameters of the foundation pit surrounding rock, and the FLAC3D model inputs were subsequently updated. Finally, simulated results were validated against field measurements. The maximum relative error of surrounding rock displacement reached 8%, with only 3% at the pit center. The largest settlement occurred in the eastern section, where the relative error was 5%. For anchor cable forces, the maximum relative error was 7.9%. This study employed a PSO-BP neural network to invert the physical–mechanical parameters of the foundation pit surrounding rock and introduced a two-stage validation using measured displacements and anchor cable forces. The approach enhances inversion accuracy and provides a practical reference for similar foundation pit engineering applications.

Ahmed M. Elazzazy, Mohammed N. Baeshen, Khalid M. Alasmi et al.

The global nutraceutical industry is experiencing a paradigm shift, driven by an increasing demand for functional foods and dietary supplements that address malnutrition and chronic diseases such as obesity, diabetes, cardiovascular conditions, and cancer. Traditional plant- and animal-derived nutraceuticals face limitations in scalability, cost, and environmental impact, paving the way for microbial biotechnology as a sustainable alternative. Microbial cells act as bio-factories, converting nutrients like glucose and amino acids into valuable nutraceutical products such as polyunsaturated fatty acids (PUFAs), peptides, and other bioactive compounds. By harnessing their natural metabolic capabilities, microorganisms efficiently synthesize these bioactive compounds, making microbial production a sustainable and effective approach for nutraceutical development. This review explores the transformative role of microbial platforms in the production of nutraceuticals, emphasizing advanced fermentation techniques, synthetic biology, and metabolic engineering. It addresses the challenges of optimizing microbial strains, ensuring product quality, and scaling production while navigating regulatory frameworks. Furthermore, the review highlights cutting-edge technologies such as CRISPR/Cas9 for genome editing, adaptive evolution for strain enhancement, and bioreactor innovations to enhance yield and efficiency. With a focus on sustainability and precision, microbial production is positioned as a game-changer in the nutraceutical industry, offering eco-friendly and scalable solutions to meet global health needs. The integration of omics technologies and the exploration of novel microbial sources hold the potential to revolutionize this field, aligning with the growing consumer demand for innovative and functional bioactive products.

Rebecca A. Powell, Emily A. Atkinson, Poppy O. Smith et al.

Tissue engineering has the potential to overcome the limitations of using autografts in nerve gap repair, using cellular biomaterials to bridge the gap and support neuronal regeneration. Various types of therapeutic cells could be considered for use in aligned collagen-based engineered neural tissue (EngNT), including Schwann cells and their precursors, which can be derived from human induced pluripotent stem cells (hiPSCs). Using Schwann cell precursors may have practical advantages over mature Schwann cells as they expand readily in vitro and involve a shorter differentiation period. However, the performance of each cell type needs to be tested in EngNT. By adapting established protocols, hiPSCs were differentiated into Schwann cell precursors and Schwann cells, with distinctive molecular profiles confirmed using immunocytochemistry and RT-qPCR. For the first time, both cell types were incorporated into EngNT using gel aspiration–ejection, a technique used to align and simultaneously stabilise the cellular hydrogels. Both types of cellular constructs supported and guided aligned neurite outgrowth from adult rat dorsal root ganglion neurons in vitro. Initial experiments in a rat model of nerve gap injury demonstrated the extent to which the engrafted cells survived after 2 weeks and indicated that both types of hiPSC-derived cells supported the infiltration of host neurons, Schwann cells and endothelial cells. In summary, we show that human Schwann cell precursors promote infiltrating endogenous axons in a model of peripheral nerve injury to a greater degree than their terminally differentiated Schwann cell counterparts.

Yu Zhong, Yu Zhong, Yongtao Zhang et al.

Coral islands and reefs serve as the sole land-based foundations in the open ocean, and their unique engineering characteristics pose significant challenges for cross-sea bridge construction. This study focused on the China-Maldives Friendship Bridge to investigate the load-bearing mechanisms and construction techniques of pile foundations on coral islands and reefs. Field and laboratory tests on coral reef debris and reef limestone yielded a method to evaluate the compactness of coral reef debris using dynamic penetration test (DPT) blow count. Different classification methods were employed to perform engineering classification and evaluation of the coral reef debris and reef limestone strata. Shear tests on the coral reef debris-pile interface and model tests on driven steel pipe piles clarified the mechanism underlying low pile side friction resistance in coral reef debris strata, while a modified formula for calculating side friction resistance was provided. Shear tests of reef limestone-concrete interfaces with different surface morphologies, combined with field pile testing, yielded recommended mobilization coefficient (c2) of side friction resistance for cast-in-place piles in reef limestone strata. A hydraulic automatic opening and closing chuck for driven piles, a large cantilever guiding frame system with a fuse mechanism, and specialized drilling heads for cast-in-place piles, were developed to ensure pile construction quality.

PENG Hao 1 , HAN Yu 1, LIANG Ming 1 , XIE Weiwei 1, 2, ZHU Menglong 1, SONG Guanxian 1, HUANG Nenghao 1, WU Menglan 1, ZENG Nongjian 1, XIE Yunze 3

In response to the current situation of static fragmentation in tunnel construction safety assessment system, insufficient multi-source information, and the challenge of ensuring the reliability of assessment methods, this paper proposes an integrated dynamic safety assessment technology and engineering application system for tunnel construction based on multi-source information fusion. With a multi-dimensional and multi-scale concept, the tunnel construction cycle is divided into three nested scales: survey and design, advance prediction, and excavation monitoring, as well as three source dimensions under each scale: geological information, construction information, and prediction information, to form a multi-source safety information assessment index system. This system can meet the requirements of survey and design in alignment with construction progress: two overall risk assessments under the advance prediction scale, and various specialized construction safety assessments under the excavation monitoring scale. To enhance the rationality and reliability of safety assessment results, the D-S evidence theory serves as the fusion framework. The interval Euclidean distance method and average evidence method optimize the basic probability assignment calculation and conflicting evidence fusion in the multi-source information fusion process. The implementation of this comprehensive dynamic safety assessment method and system is illustrated through a tunnel engineering project. Results show consistency between the assessment outcomes and actual site conditions. Further discussion, comparison, and verification demonstrate its rationality and reliability, it can provide valuable reference and practical guidance for tunnel construction safety assessment and control.

Nianchun Deng, Haoxu Li, Jingyao Ni et al.

Abstract Concrete-filled steel tubes (CFSTs) have been increasingly utilized in engineering due to their excellent mechanical properties. Ensuring a solid bond between a steel tube and concrete is essential for optimizing their synergistic effect. This study introduces an internally welded steel bar structure within the inner wall of a steel tube to enhance the bond properties at the connection interface. The influence of various configurations of steel bars welded to the inner surface of the tube on the bond strength is investigated considering the impact of vibration on the load-bearing capacity of the component. This study comprises two groups of specimens, one with vibration and one without vibration, for a total of ten specimens. Each group included CFST members with five distinct internal welded steel bar structures. The experimental results, including load–displacement curves and strain data of the steel tube, were used to assess the impact of the internal welded steel bar configurations on the steel–concrete interface. The sliding process is described by correlating test data with curves and observed phenomena. To comprehensively compare the effects of structural dimensions on the bonding and slipping properties of the welded bars, finite element simulations replicating the experimental conditions were carried out using ABAQUS software, and the simulation results agreed with the experimental observations. The study demonstrated that incorporating internal welded steel bars substantially enhances the bond strength of steel pipe–concrete interfaces. While vibration weakens the bond strength in CFST members, internal welded steel bars mitigate this effect. These findings improve the structural performance of CFST structures and their resilience to external vibrations.

Fangjian Hu, Long Chen, Zineng Huang et al.

The main cable strands of self-anchored suspension bridges are typically anchored directly to the back of concrete or steel girders, a construction method that has durability issues. To address this problem, a new combined anchorage structure using finished cables and a connecting shaft is proposed. This anchorage structure is connected to the end of the main cable strands via the connecting shaft. This article provides a detailed description of the design concept and specifics of this new anchorage structure, including installation methods and procedures for removal and reinstallation during bridge operation. Full-scale static load tests validated the feasibility of the proposed design. This new structure improves the durability of the main cable anchorage section, allows for its replaceability, and can be extended to other similar applications, offering considerable reference value.

Niccolò DeCarlo, Ciro Romano, Gianluca Granero et al.

The article explores the integration of the Digital Twin concept with Federated Learning techniques for monitoring critical infrastructure. This approach allows for local data processing and knowledge transfer between different infrastructures, minimizing the amount of data sent to the cloud. Benefits include enhanced data security, operational efficiency, and more proactive maintenance. Through practical examples, it demonstrates how these technologies can revolutionize the management of critical infrastructure.

Idowu Itiola, Usama El Shamy

This study presents a microscale framework for investigating the seismic stability of bridge-pier structures using the discrete element method (DEM), with a focus on rocking isolation mechanisms. The piers and the deck are modeled as rigid blocks that follow rigid body dynamics. The rigid block is modeled as a collection of glued particles with geometrical arrangement and physical properties that mimic an actual block. To facilitate numerical contact points between the base of the block and the flat base wall, smaller particle sizes were introduced at the base of the block. A Hertz contact model was employed to model the interaction between contacting entities for better estimation of the contact constitutive parameters. Validation was performed using well-documented experimental data featuring the free-rocking of a granite stone block as well as existing analytical techniques. DEM simulations were performed on single blocks as well as on a bridge deck-pier system subjected to dynamic and seismic loadings. The study shows the effectiveness of rocking isolation through a comparative analysis of acceleration and angular velocity under varying seismic intensities, with acceleration reduction up to 70% for piers and 60% for the deck in a high-intensity scenario, affirming the potential of rocking isolation as a viable seismic mitigation strategy. The study monitors the structural response, contact mechanics, and energy dissipation of the pier–deck system. The application of the DEM model advances the analysis of bridge pier and deck interactions under seismic loads, providing new insights into the detailed behavior of rocking bridge piers and their potential for seismic isolation.

Ming Yang, Hongwei Xu

In order to understand the application of fiber Bragg grating sensing technology and physical models in bridge detection, the author proposes an application research based on fiber Bragg grating sensing technology and physical models in bridge detection. The author first introduced the principle of fiber optic sensors, then analyzed the technology of demodulating fiber optic gratings, and discussed the application of fiber optic sensing technology in bridge detection, effectively improving the monitoring effect and safety performance of bridges. Secondly, in response to the problem that electrical sensors are difficult to meet the long-term monitoring requirements of bridge structures, it is proposed to use fiber optic grating vibration sensors to monitor the vibration status of bridges, and the feasibility of the scheme is demonstrated through theoretical and experimental results. FBG sensor parameters: Select a cylindrical mass block with a diameter of 3 mm and a height of 4 mm, weighing 0.6 g, a fiber length of 65 mm, and a pre stretching amount of 1.3 mm. Fiber Bragg grating sensors not only meet the requirements of frequency measurement range and temperature adaptation range, but also have advantages such as resistance to electromagnetic interference, simple appearance structure, convenient deployment, and good long-term stability. They have good engineering application prospects.

Yi-Seul Kim, Wongi S. Na

Up to date, biomimicry has aided in designing novel ideas and solving various problems in the field of civil engineering. For example, the concept of a load carrying process from a tree can be used to design an effective bridge. Inspired by nature, the authors have adopted the concept of how spiders use vibrations to monitor the state of the web and the presence of prey. A nondestructive testing method known as the electromechanical impedance technique has been proven to be effective when detecting local damage. However, the aforementioned technique uses a high frequency which results in a limited sensing range. Thus, to overcome this problem, an idea using the piezoelectric transducer combined with wires was introduced and tested against composite plates subjected to debonding damage. From the experiment results, the concept introduced from this research shows that biomimicry can increase the sensing range for electromechanical impedance technique which may allow one to create a monitoring system with minimal cost.

Si Jie Lim, Siti Nurbaya Oslan

Background α-amylases catalyze the endo-hydrolysis of α-1,4-D-glycosidic bonds in starch into smaller moieties. While industrial processes are usually performed at harsh conditions, α-amylases from mainly the bacteria, fungi and yeasts are preferred for their stabilities (thermal, pH and oxidative) and specificities (substrate and product). Microbial α-amylases can be purified and characterized for industrial applications. While exploring novel enzymes with these properties in the nature is time-costly, the advancements in protein engineering techniques including rational design, directed evolution and others have privileged their modifications to exhibit industrially ideal traits. However, the commentary on the strategies and preferably mutated residues are lacking, hindering the design of new mutants especially for enhanced substrate specificity and oxidative stability. Thus, our review ensures wider accessibility of the previously reported experimental findings to facilitate the future engineering work. Survey methodology and objectives A traditional review approach was taken to focus on the engineering of microbial α-amylases to enhance industrially favoured characteristics. The action mechanisms of α- and β-amylases were compared to avoid any bias in the research background. This review aimed to discuss the advances in modifying microbial α-amylases via protein engineering to achieve longer half-life in high temperature, improved resistance (acidic, alkaline and oxidative) and enhanced specificities (substrate and product). Captivating results were discussed in depth, including the extended half-life at 100 °C, pH 3.5 and 10, 1.8 M hydrogen peroxide as well as enhanced substrate (65.3%) and product (42.4%) specificities. These shed light to the future microbial α-amylase engineering in achieving paramount biochemical traits ameliorations to apt in the industries. Conclusions Microbial α-amylases can be tailored for specific industrial applications through protein engineering (rational design and directed evolution). While the critical mutation points are dependent on respective enzymes, formation of disulfide bridge between cysteine residues after mutations is crucial for elevated thermostability. Amino acids conversion to basic residues was reported for enhanced acidic resistance while hydrophobic interaction resulted from mutated hydrophobic residues in carbohydrate-binding module or surface-binding sites is pivotal for improved substrate specificity. Substitution of oxidation-prone methionine residues with non-polar residues increases the enzyme oxidative stability. Hence, this review provides conceptual advances for the future microbial α-amylases designs to exhibit industrially significant characteristics. However, more attention is needed to enhance substrate specificity and oxidative stability since they are least reported.

Peng Wang, Shuyi Ma, Zhongwen Yue et al.

According to the lack of theoretical research on the spatial effect of the foundation pit, the concept of the reasonable arch curve (bending moment on the curve is zero everywhere) is introduced to establish a new three-dimensional instability failure theoretical model of the water-rich foundation pit. Taking the K6 + 650 ∼ K6 + 880 section of the GUI River Foundation Pit as an example, the active earth pressure acting on the supporting structure per unit length, the critical length–depth ratio, the main influence range, and the influence coefficient of spatial effect are calculated and compared with previous research results and field monitoring data, in order to explore the influence law of the length, depth, and moisture content of soil layers on the spatial effect. The results show the following: (1) When the length–depth ratio is greater than 1, the foundation pit presents the failure mode of the end arch curve and middle straight line, and when the length–depth ratio is greater than 3, the main influence range has a linear relationship with the depth and a negative correlation with the moisture content, but little relationship with the length. (2) The active earth pressure is approximately a quadratic function of the depth, and there is a more than 16% increase when the moisture content increases from 21% to 25%. (3) The change law of the horizontal displacement of the pile top monitored verifies the rationality and progressiveness of the new instability failure model. Through this study, the spatial effect revealed can provide the theoretical basis for pile support of the foundation pit.

Jurgis Zagorskas, Zenonas Turskis

Non-motorized pedestrian and bicycle traffic is an effective and efficient tool for reducing the negative environmental impacts of transport and improving the quality of life in urban conditions. The strategies of creating new attractive spaces on the waterfront are prevalent amongst the municipalities in different countries. This kind of development intends the construction of new connection bridges, usually meant solely for walking and cycling. There are a significant number of studies covering the theme of pedestrian bridges, but the studies typically focus on technical parameters – serviceability, stress and vibrations, specifications for the design. Researchers and stakeholders rarely discuss displacement strategy, expenditure and future usability. This study aims to find out the best and the most useful bridge locations that would contribute to pedestrian network improvement, would add value to city image and give other benefits. A novel hybrid Multi-Criteria Decision-Making (MCDM) model, based on five different multi-criteria decision-making methods: Multiplicative Exponential Weighting (MEW), method of Evaluation Based on Distance from Average Solution (EDAS), an Additive Ratio Assessment (ARAS) method, expert judgement, and Step‐Wise Weight Assessment Ratio Analysis (SWARA), is presented. A developed model allows solving complicated problems and finding a rationally, balanced solution. Arguments derived from this study help politicians and town planners as well as society.

Fernando Moreu, Fernando Moreu, Fernando Moreu et al.

Human induced dynamic forces on structures are of interest in the area of human-environment interfaces. The research community is interested in characterizing human decisions and providing information on the consequences of human actions to control those human forces more effectively. Dynamic structures can vibrate under human motion. In the context of human–structure interactions (HSI), dance induced vibrations can be quantified with sensors. This data can provide a unique opportunity for dancers to understand the quality of their dance with objective metrics. Previous work in capturing dance moves required wearable sensors attached to the dancer’s body. Often an intrusive process, this method is not scalable if dancers are not familiar with technology and it limits their participation without access to special studios or facilities. If simple, deployable technology could be available to dancers, they could monitor their dance without engineers. This research integrates dancers’ interest in qualifying dance motion and engineering curiosity to study human induced vibrations. As a part of the framework, researchers used two indexes to differentiate between a well synchronized group dance from asynchronous moves. The two indexes are the Harmony Index and the Coordination Index, respectively, and are validated against the Visual Index, a qualitative index obtained from an expert who judged dance moves based on one video capture. The indexes were derived from measurements of the movement of the structure dynamically excited by the dancers, hence quantifying dance coordination. These two indexes are based on time history data obtained from sensors installed on a wooden bridge where dancers performed at different levels of proficiency. The results of this research show that the two indexes sort effectively the quality of the dancers, when validated with the Visual Index. As a result, this research proposes using Low-cost efficient wireless intelligent sensor (LEWIS) to objectively sort different levels of dance quality which could be expanded to study the HSI for design and assessment of the structural systems used for dancing, such as performance halls and ballrooms.

Andrea Maroni, Enrico Tubaldi, Neil Ferguson et al.

Scour jeopardises the safety of many civil engineering structures with foundations in riverbeds and it is the leading cause for the collapse of bridges worldwide. Current approaches for bridge scour risk management rely mainly on visual inspections, which provide unreliable estimates of scour and of its effects, also considering the difficulties in visually monitoring the riverbed erosion around submerged foundations. Thus, there is a need to introduce systems capable of continuously monitoring the evolution of scour at bridge foundations, even during extreme flood events. This paper illustrates the development and deployment of a scour monitoring system consisting of smart probes equipped with electromagnetic sensors. This is the first application of this type of sensing probes to a real case-study for continuous scour monitoring. Designed to observe changes in the permittivity of the medium around bridge foundations, the sensors allow for detection of scour depths and the assessment of whether the scour hole has been refilled. The monitoring system was installed on the A76 200 Bridge in New Cumnock (S-W Scotland) and has provided a continuous recording of the scour for nearly two years. The scour data registered after a peak flood event (validated against actual measurements of scour during a bridge inspection) show the potential of the technology in providing continuous scour measures, even during extreme flood events, thus avoiding the deployment of divers for underwater examination.

Klier Tomáš, Míčka Tomáš, Polák Michal et al.

In the technical practice there is very often a need of axial force determination in the important structural elements of a building during its construction or operational state with adequate precision. The magnetoelastic method is one of the five experimental techniques usually used for that purpose in civil engineering practice. The modified magnetoelastic method is especially aimed on experimental evaluation of the axial forces in the prestressed steel reinforcements on prestressed concrete structures and it is usable not only for newly built structures but in particular for existing ones. New information and knowledge about practical application of the new approach based on the magnetoelastic principle is introduced in the paper. The results of three experiments are summarized, which were realized on the full locked cable PV 150 standardly used as a cable stay strand, on the MUKUSOL threadbar 15FS 0000 generally applied as a temporary prestressed reinforcement and on some prestressed tendons of an existing concrete road bridge, which is about thirty years old.

Xueyin Zhang, Yonghai Xu, Yunbo Long et al.

Modular solid-state transformers (SSTs) are suitable for various voltage- and power-level applications. State-of-the-art modular-SST topologies contain a considerable quantity of high-frequency transformers (HFTs) and power switches, thereby increasing the costs, difficulty, and workloads of engineering. To overcome this challenge, a new SST topology family, namely, hybrid-frequency cascaded full-bridge SST (HCFB-SST), is established on the basis of the concept of hybrid-frequency modulation. In comparison with modular-multilevel converter SST (M²LC-SST) or CFB-SST, the HCFB-SST uses only 50%-66.7% and 1.11%-10% the device count of power switches and HFTs, respectively, in typical applications, thereby obtaining considerable cost savings. It also achieves a cost reduction of sub-module redundancy. In addition, HCFB-SSTs have simple engineering and compact structures. A hybrid-frequency modulation method is proposed for a low well-balanced average switching frequency and a high equivalent switching frequency without monitoring the bridge-arm current. Analysis and comparison of the semiconductor loss with existing topologies are presented. The simulation studies are conducted to validate the effective function of HCFB-SST and the proposed modulation method.

Alberto Maria Avossa, Cristoforo Demartino, Francesco Ricciardelli

This paper aims at pointing out some misconceptions concerning the evaluation of the walking-induced dynamic response of footbridges, and their impact on design procedures. First, a review of the existing Code provisions is briefly presented. In particular single-walker models and multiple-walker models are addressed; in doing so, models originally presented in different forms are made homogeneous for the purpose of comparison; their limits of applicability and advantages are pointed out. Then, the response of six steel box girder footbridges with different spans is evaluated following the provisions of existing Standards and Guidelines, and compared with allowable comfort levels. The comparison showed a wide scatter of the results, revealing some inconsistencies of the procedures, and underlining a clear need for their critical revision.