Hasil untuk "Bridge engineering"

Yongxin Chen, T. Georgiou, M. Pavon

In 1931--1932, Erwin Schr\"odinger studied a hot gas Gedankenexperiment (an instance of large deviations of the empirical distribution). Schr\"odinger's problem represents an early example of a fundamental inference method, the so-called maximum entropy method, having roots in Boltzmann's work and being developed in subsequent years by Jaynes, Burg, Dempster, and Csisz\'ar. The problem, known as the Schr\" odinger bridge problem (SBP) with ``uniform"" prior, was more recently recognized as a regularization of the Monge-Kantorovich optimal mass transport (OMT) problem, leading to effective computational schemes for the latter. Specifically, OMT with quadratic cost may be viewed as a zerotemperature limit of the problem posed by Schr\"odinger in the early 1930s. The latter amounts to minimization of Helmholtz's free energy over probability distributions that are constrained to possess two given marginals. The problem features a delicate compromise, mediated by a temperature parameter, between minimizing the internal energy and maximizing the entropy. These concepts are central to a rapidly expanding area of modern science dealing with the so-called Sinkhorn algorithm, which appears as a special case of an algorithm first studied in the more challenging continuous space setting by the French analyst Robert Fortet in 1938--1940 specifically for Schr\"odinger bridges. Due to the constraint on end-point distributions, dynamic programming is not a suitable tool to attack these problems. Instead, Fortet's iterative algorithm and its discrete counterpart, the Sinkhorn iteration, permit computation of the optimal solution by iteratively solving the so-called Schr\" odinger system. Convergence of the iteration is guaranteed by contraction along the steps in suitable metrics, such as Hilbert's projective metric. In both the continuous as well as the discrete time and space settings, stochastic control provides a reformulation of and a context for the dynamic versions of general Schr\" odinger bridge problems and of their zero-temperature limit, the OMT problem. These problems, in turn, naturally lead to steering problems for flows of one-time marginals which represent a new paradigm for controlling uncertainty. The zero-temperature problem in the continuous-time and space setting turns out to be the celebrated Benamou--Brenier characterization of theMcCann displacement interpolation flow in OMT. The formalism and techniques behind these control problems on flows of probability distributions have attracted significant attention in recent years as they lead to a variety of new applications in spacecraft guidance, control of robot or biological swarms, sensing, active cooling, and network routing as well as in computer and data science. This multifaceted and versatile framework, intertwining SBP and OMT, provides the substrate for the historical and technical overview \ast Received by the editors May 22, 2020; accepted for publication (in revised form) October 29, 2020; published electronically May 6, 2021. https://doi.org/10.1137/20M1339982 Funding: This work was partially supported by the NSF under grants 1807664, 1839441, 1901599, and 1942523, by the AFOSR under grant FA9550-17-1-0435, and by University of Padova Research Project CPDA 140897. \dagger School of Aerospace Engineering, Georgia Institute of Technology, Atlanta, GA 30332 USA (yongchen@gatech.edu). \ddagger Department of Mechanical and Aerospace Engineering, University of California, Irvine, CA 92697 USA (tryphon@uci.edu). \S Dipartimento di Matematica ``Tullio Levi-Civita,"" Universit\` a di Padova, 35121 Padova, Italy (pavon@math.unipd.it). 249 D ow nl oa de d 11 /0 9/ 21 to 1 47 .1 62 .2 13 .1 11 R ed is tr ib ut io n su bj ec t t o SI A M li ce ns e or c op yr ig ht ; s ee h ttp s: //e pu bs .s ia m .o rg /p ag e/ te rm s

Wei Lu, Chenbing Ni, Youqiang Wang et al.

Improving the surface quality and controlling the microstructure evolution of difficult-to-cut materials are always challenges in high-speed machining (HSM). In this paper, surface topography, defects and roughness are assessed to characterize the surface features of 7050 aluminum alloy (Al 7050) under HSM conditions characterized by high temperature, strain and strain rate. Based on multi-physical field coupling, the mechanism of microstructure evolution of Al 7050 is investigated in HSM. The results indicate that the surface morphology and roughness of Al7050 during HSM are optimal at <i>f_z</i> = 0.025 mm/z, and the formation of surface defects (adherent chips, cavities, microcracks, material compression and tearing) in HSM is mainly affected by thermo-mechanical coupling. Significant differences are observed in the microstructure of different machined subsurfaces by electron backscatter diffraction (EBSD) technology, and high cutting speeds and high feed rates contributed to recrystallization. The crystallographic texture types on machined subsurface are mainly {110}<112> Brass texture, {001}<100> Cube texture, {123}<634> S texture and {124}<112> R texture, and the crystallographic texture type and intensity are significantly affected by multi-physical field coupling. The elastic–plastic deformation and microstructural evolution of Al7050 alloy during the HSM process are mainly influenced by the coupling effects of multiple physical fields (stress–strain field and thermo-mechanical coupling field). This study reveals the internal mechanism of multi-physical field coupling in HSM and provides valuable enlightenment for the control of microstructure evolution of difficult-to-cut materials in HSM.

Najib Zemed, Hanane Moulay Abdelali, Kaoutar Mouzoun et al.

Abstract Bridges play a critical role in ensuring the safe and continuous movement of people and goods, making their structural integrity over time a key concern in civil engineering. This study introduces a novel two-stage Reliability-Based Design Optimization (RBDO) approach for optimizing the cross-sectional dimensions of reinforced concrete bridge girders at the end of their service life. The method explicitly accounts for key time-dependent degradation mechanisms-creep, shrinkage, corrosion, and traffic growth-often neglected or treated in isolation in prior research. The first stage involves a deterministic optimization to provide a cost-effective initial design. The second stage applies an active learning-based RBDO using a hybrid surrogate model that combines artificial neural networks (ANN), radial basis functions (RBF), and support vector regression (SVR). This adaptive strategy significantly reduces the number of full-model evaluations required to estimate failure probabilities, ensuring both computational efficiency and accuracy. Validation against benchmark problems confirms the robustness of the proposed framework in terms of both reliability estimation and optimization. When applied to a real bridge case, the method achieved convergence in only 11 deterministic and 15 RBDO iterations, resulting in a 47% reduction in computational cost compared to a standard Adaptive Kriging Monte Carlo Simulation (AK-MCS)-based approach. Overall, the proposed methodology enables a more realistic, economical, and computationally efficient design of bridge structures over their entire lifespan.

Jinzi Zheng, Zhiyang Liu, Chenguang Li et al.

Under the increasing threat of extreme weather events, road infrastructure faces significant risks of flood-induced damage. Traditional manual inspection methods are insufficient for modern highway emergency response, which requires higher efficiency and accuracy. To enhance the precision and accuracy of flood damage identification, this study proposes an intelligent recognition system that integrates a multimodal large language model with a structured knowledge base. The system constructs a professional repository covering eight typical categories of flood damage, including roadbed, pavement, and bridge components, with associated attributes, visual features, and mitigation strategies. A vectorized indexing mechanism enables fine-grained semantic retrieval, while task-specific templates and prompt engineering guide the multimodal model, such as Qwen-VL-Max, which extracts risk elements from image–text inputs and generating structured identification results with expert recommendations. The system is evaluated on a real-world highway flood damage dataset. The results show that the knowledge-enhanced model performs better than the baseline and prompt-optimized models. It reaches 91.5% average accuracy, a semantic relevance score of 4.58 out of 5, and 85% robustness under difficult conditions. These results highlight the strong domain adaptability and practical value for real-time flood damage assessment and emergency response.

Xuzhao Lu, Chenxi Wei, Limin Sun et al.

The reconstruction of bridge responses has been a significant area of focus within the field of structural health monitoring. This process entails the cross-reconstruction of responses from various cross-sections to identify any anomalies at specific locations, which may indicate the presence of structural defects. Traditional research has concentrated on simulating the relationships between different cross-sections for both high- and low-frequency components in isolation. However, this study introduces an innovative approach using a residual network (ResNet) to reconstruct high-frequency bridge responses under vehicular loading and demonstrates its applicability to low-frequency response reconstruction as well. The theoretical basis of this method is established through an analysis of the dynamics within a simplified vehicle-bridge-interaction (VBI) system. This analysis reveals that the transfer matrices for both high- and low-frequency components remain consistent across various loading conditions. Then, a data interception technique is introduced to separate high-frequency, low-frequency, and temperature-related components based on their spectral characteristics. The ResNet modeled the inter-sectional relationships of the high-frequency components and was then used to reconstruct the low-frequency responses under vehicular loading. The methodology was validated using a series of finite element models, confirming the uniformity of the transfer matrix between high- and low-frequency vibration components of the bridge. Field testing was also conducted to evaluate the practical effectiveness of the method. The proposed transfer–reconstruction method is expected to significantly reduce training dataset requirements compared with existing methods, thereby enhancing the efficiency of structural health monitoring systems.

Dashun Cui, Chunwei Zhang

The crack detection method based on image processing has been a new achievement in the field of civil engineering inspection in recent years. Column piers are generally used in bridge structures. When a digital camera collects cracks on the pier surface, the loss of crack dimension information leads to errors in crack detection results. In this paper, an image stitching method based on Speed-Up Robust Features (SURFs) is adopted to stitch the surface crack images captured from different angles into a complete crack image to improve the accuracy of the crack detection method based on image processing in curved structures. Based on the proposed method, simulated crack tests of vertical, inclined, and transverse cracks on five different structural surfaces were conducted. The results showed that the influence of structural curvature on the measurement results of vertical cracks is very small and can be ignored. Nevertheless, the loss of depth information at both ends of curved cracks will lead to errors in crack measurement outcomes, and the factors that affect the precision of crack detection include the curvature of the surface and the length of the crack. Compared with inclined cracks, the structural curvature significantly influences the measurement results of transverse cracks, especially the length measurement results of transverse cracks. The image stitching method can effectively reduce the errors caused by the structural curved surface, and the stitching effect of three images is better than that of two images.

Drew Voghel, Talat Salama

The primary objective of this study is to evaluate the sustainability of highway sign supports through field testing and finite element analysis. The study aims to develop a predictive maintenance model to evaluate the service life of these structures. Sign support systems are important structures in the Connecticut Department of Transportation (CTDOT) bridge management system. Periodic sustainability inspections and maintenance activities are needed as a long-term, cost-effective maintenance strategy. The research involved non-destructive field testing of a cantilever-type highway sign support, followed by finite element modeling using Highway Sign Structures Engineering (HSE) by SAFI software. Data from accelerometers, strain gauges, and anemometers were collected and analyzed to validate the model. The experimental setup was done in collaboration with CTDOT. The data was collected and analyzed, and it was usedto verify the three-dimensional finite element (FE) model developed, which was used to test the structure's design capacity. The study found that the sign support structure experienced significant wind loading on a few occasions, with stress levels reaching about 20% of its elasticlimit. The finite element model accurately predicted structural behavior under design load conditions, demonstrating its potential for predictive maintenance applications.

Zhao-jun Zhang, Wen-wei Wang, Jing-shui Zhen et al.

Abstract In order to clarify the effect of mechanical tensioning and SMA wire heating recovery on introducing prestress into CFRP sheet strengthened reinforced concrete (RC) beams, an experimental research on the bending performance of prestressed CFRP sheet strengthened RC beams was conducted. Based on the test results, a bending carrying capacity model for RC beams externally strengthened with prestressed CFRP sheets was proposed. The model provides calculation methods for the decompression moment, cracking moment, yielding moment, and ultimate moment, corresponding to different failure modes of the RC beams strengthened with externally bonded prestressed CFRP sheets. Four experimental beams were designed to verify the accuracy of the model with the prestresses of 100 MPa and 200 MPa. The results show that during the yield stage and strengthening stage, the loading-unloading stress-strain relationship curves of SMA wire under different prestrains are basically consistent. When the prestrain of SMA wire is 10%, the maximum recovery stress reaches 448.5 MPa. Under the same prestrain conditions, the maximum recovery stress of CFRP sheets was reduced by 37.8–39.5% when the prestress was introduced through heating recovery of SMA wires. The failure mode of mechanically tensioned prestressed CFRP sheet strengthened beams is the CFRP sheet debonding caused by mid-span bending cracks, while the failure mode of strengthened beams with prestressed CFRP sheet by SMA wire heating recovery is the CFRP sheet end debonding. The cracking moment and yield moment of the strengthened beams are significantly increased by two methods of introducing prestressing. The stiffness improvement of mechanically tensioned prestressed CFRP sheet strengthened beam is relatively large. While, the prestressed CFRP sheet strengthened beam by SMA wire heating recovery gradually experience end peeling failure of the CFRP sheet, and the prestressing effect does not effectively limit the development of cracks, resulting in limited stiffness improvement. The calculation results are in good agreement with the experimental results, proving that the proposed method for analyzing the entire bending process can be used to predict the bending mechanical properties of the prestressed CFRP sheet strengthened beams.

Yuriy O. Nosov, Anna A. Kamenskikh

The study of the rheological properties of a lubricant allows for the assessment of the structure’s durability in which they are used. Computer engineering enables the prediction of the structure performance using refined mathematical models of its materials. This paper presents an experimental investigation of the rheological behavior of a lubricant that is actively used in bridge structures. The paper proposed a methodology for determining the rheological characteristics of the lubricant using a rotational viscometer. Additionally, the article performed the task of identifying the mathematical model of the lubricant behavior based on the Maxwell body, using two approaches: the Anand model and the Prony series. The proposed models allow for numerical modeling of the structure’s performance throughout their lifecycle within the scope of computer engineering.

Hui Yan, Yaning Wang, Yan Yan et al.

Wind loads can endanger the safety and stability of bridges, especially long-span cable-supported bridges. Therefore, it is important to evaluate the potential wind loads during the bridge design stage. Traditionally, wind load evaluation is performed by wind tunnel testing, which is relatively expensive. With the development of computational fluid dynamics and high-performance computing, numerical simulations are becoming more accessible for designers. However, the costs required for accurate numerical results are still high, especially for high-fidelity simulations. Under this condition, searching for a more efficient method to evaluate the wind loads in bridge wind engineering has become a new goal. It seems that flow visualization is a good entry point. Although flow visualization techniques have been developed in recent years, it remains difficult to extract velocity and pressure fields from images. To address this problem, physics-informed neural networks (PINNs) have been developed and validated. This study establishes a PINN to investigate the two-dimensional viscous incompressible fluid flow passing a generic bridge deck section. Two cases with different Reynolds numbers are tested. After careful training, it is found that the PINN can accurately extract the velocity and pressure fields from the concentration field and predict the drag and lift coefficients. The results demonstrate that PINNs are a promising method for extracting useful flow information from flow visualization data in engineering applications.

Taha Mahdi, Mohammed Al-Neami, Falah Raheel

Increasing the cross-sectional area of the piles or adding wings to the piles are two strategies for increasing the bearing capacity of the piles to resist lateral stresses. Small and full-scale finite element models were used to investigate the effect of adding the wings on the laterally loaded pile bearing capacity in this study. Four embedded ratios (4, 6, 8, and 10) were used with various wing dimensions and numbers. The results showed that adding wings to the pile increases the resistance to lateral loads and reduces the lateral displacement significantly. +To achieve the highest lateral resistance, the wings should be fixed parallel to the lateral load applied to the pile and close to the pile head. The ultimate lateral applied load is proportional to the rise in relative density. The lateral pile capacity was increased by 16.5%, 18.4%, and 33% in dense, medium, and loose sand, respectively, at the same length to diameter ratio (L/D). Increasing wing length improves lateral capacity significantly. At a failure, the lateral pile capacity was 18% and 8.5 % for Lw, equal to 112 mm and 56 mm, respectively. Another study's purpose was to determine how increasing the number of wings affected pile resistance. The lateral pile capacity at failure was increased by 9.8 % for two wings, 18.4 % for three wings, and 18 % for four wings.

Seyedmirsajad Mokhtarimousavi, Jason C. Anderson, Mohammed Hadi et al.

In the context of work zone safety, worker presence and its impact on crash severity has been less explored. Moreover, there is a lack of research on contributing factors by time-of-day. To accomplish this, first a mixed logit model was used to determine statistically significant crash severity contributing factors and their effects. Significant factors in both models included work-zone-specific characteristics and crash-specific characteristics, where environmental characteristics were only significant in the daytime model. In addition, results from parameter transferability test provided evidence that daytime and nighttime crashes need to be modeled separately. Further, to explore the nonlinear relationship between crash severity levels and time-of-day, as well as compare the effects of variables to that of the logit model and assess prediction performance, a Support Vector Machines (SVM) model trained by Cuckoo Search (CS) algorithm was utilized. Opening the SVM black-box, a variable impact analysis was also performed. In addition to the characteristics identified in the logit models, the SVM models also included the impacts of vehicle-level characteristics. The variable impact analysis illustrated that the termination area of the work zone is most critical for both daytime and nighttime crashes, as this location has the highest increase in severe injury likelihood. In summary, results of this study demonstrate that work zone crashes need to be modeled separately by time-of-day with a high level of confidence. Furthermore, results show that the CS-SVM models provide better prediction performance compared to the SVM and logit models.

Yangqing Liu, Yuqing Liu, Haohui Xin et al.

To improve the shear behavior and design applicability of rubber ring perfobond connectors (RPBLs), a new rubber ring that aims to make the shear stiffness of RPBLs controllable was proposed. Firstly, the conceptual design and configuration of the new rubber rings were presented and discussed. Subsequently, finite element (FE) models for modified push-out tests of new RPBLs were established based on the validated modeling method. The initial shear stiffness is dominated by the horizontal projected contact area between hole walls and concrete dowels. γ is defined as the ratio of the horizontal projected length of hollows to the diameter of holes. The shear stiffness of new RPBLs is about 35%, 60%, and 82% of the shear stiffness of PBLs when γ equals 0.25, 0.5, and 0.75, respectively. Employing the new rubber rings with varying central angles on conventional PBLs is feasible to obtain the required stiffness for RPBLs. Further, the effects of the number of sectors, the size of side wings, the central angle of hollows, the offset angle, and the thickness of rubber rings were analysed. Based on the numerical results, the proper thickness of side wings is no larger than 2 mm. The thicker side wing could reduce the confinement effects provided by surrounding concrete on concrete dowels, resulting in a drop of the yield load of new RPBLs. The number of sectors is suggested to be no less than 6 so that the shear behavior of new RPBLs is irrelevant to the offset angle. Besides, the shear stiffness is not related to the thickness of rubber rings. To improve the yield load of RPBLs and obtain the moderate recovered stiffness, the thickness of rubber rings is recommended as 2 mm. Finally, the expression for the shear stiffness of new RPBLs was proposed.

Marek Pańtak

This paper concerns the issue of the dynamic impact of people running on footbridges with particular with attention to various footstrike patterns occurring during the running (i.e. heel strike pattern and forefoot strike pattern). The results of a series of laboratory tests of vertical ground reaction force (VGRF) measurements generated by running people are presented along with the characteristics of the VGRF curves. Based on the results of the tests, a new proposal for a dynamic load model generated by people classified as heel strike runners has been developed, and corrections of the input parameters of two load models proposed by other authors have been performed. Moreover, the VGRF modelling technique using the Gaussian functions is presented along with a set of equations describing the variability of the Gaussian function parameters as a function of the frequency of running. The presented methods of the VGRF modelling allow increasing the accuracy of determining the VGRF values and, consequently, increasing the accuracy of dynamic analyses of footbridges subjected to dynamic loads generated by people running.

Madjid Gholhaki, Ghasem Pachideh

Fibre or recycled material used in the concrete improves resistance, ductility, and durability of concrete. Concrete has fire-resistant properties but the most worrying thing about reinforced concrete structures during the fire is related to rebars. Therefore, there is a suggestion about use of alternative materials such as recycled metal spring in order to reduce above mentioned risks. In this paper, we conduct laboratory study to assess performance of concrete containing recycled metal spring while using volumetric amounts of 0.2, 0.4 and 0.6% at temperatures of 25, 100, 250, 500, 700 and 900 degrees Celsius. Furthermore, compressive strength and tensile strength of the most optimal combination of spring in the concrete are compared with concrete containing steel fibre and polypropylene. The results show that spring used in the concrete improves compressive strength and tensile strength. But the more the spring is used in the concrete, the more the resistance is reduced. Therefore, if the spring with 0.2 volume percent that is considered as the most optimal combination percentage is increased by 3 times, it increases compressive strength and tensile strength. Furthermore, the optimal compressive strength of spring in different temperatures is about 2 – 3 times of steel fibre and polypropylene and its tensile strength is close to strength of steel fibre. Fibre used in concrete reduces width of the cracks created after the test by 3 times.

Yuchao Zhao, Xu Jiang, Qilin Zhang et al.

GFRP (glass-fiber-reinforced polymer), as a composite material, possesses many favorable properties including high strength and low weight and is amenable to unique processing methods; therefore, it is a potential free-form surface material. However, the complex design theory owing to anisotropy limits its application. Thus, a simplified material solution becomes significant. In this study, the strength and stiffness of orthotropic symmetrical GFRP laminates are derived theoretically, and a simplified material solution is proposed to simplify the anisotropy as isotropy. Then, using the numerical simulation of an actual orthotropic symmetrical GFRP laminate free-form facade structure, the effectiveness of the simplified material solution is analyzed and evaluated. This solution can provide guidance for similar GFRP facades and further promote the application of GFRP in engineering.

Marina Milner-Bolotin, Carlos C. F. Marotto

This paper presents a meta-analysis of the literature on parental engagement with children’s formal and informal science, technology, engineering and mathematics (STEM) education. Five recurrent themes have emerged from the literature review: The challenges of supporting parents with children’s STEM education; STEM education as a bridge between school and family; STEM education as a gateway for children’s future economic success; STEM education as a vehicle for promoting student communication skills; and, the role of hands-on inquiry-based activities in enhancing student engagement. We also outline some international informal STEM education initiatives, their scope, challenges and impact.

Huaxin Chen, Yongchang Wu, Huiyun Xia et al.

Ice adhesion to materials is a significant concern in many fields. Hydrophobic surface has been used for anti-icing in fields of aircraft or transmission line, which prove to be efficacious and economical. However, such technique is seldom employed for road deicing, because of the texture and service environment of pavement. Instead, deicers such as rock salt are frequently used, which leads to serious corrosion problem of roads and bridges. In this paper, a number of studies that characterize mechanism of ice adhesion to common substrates, specifically to pavement, are reviewed. The most important researches undertaken on ice adhesion strength affecting factors are presented. An overview of studies carried out to find hydrophobic surface for asphalt and cement concrete pavement anti-icing are presented. It was verified that the hydrophobicity had high correlation with icephobicity, and nano-engineered asphalt and cement concrete pavement surface exhibited favorable hydrophobicity, and also had good performance on weakening pavement-ice bonding. However, most ice-repelling pavements obtain hydrophobic surface via low surface energy coating, which could not exist on pavement for a long time under wheel abrasion. And the nano/micro structures on hydrophobic surfaces are also vulnerable and consumable. Thus, the long-term effect of hydrophobic surface still need to be improved, and durability of the hydrophobic surface should be the research and development priorities of ice-repelling pavement. Keywords: Hydrophobic coating, Ice adhesion, Surface science, Pavement deicing

François Bédard, François Bédard, Eric Biron et al.

A wide variety of antimicrobial peptides produced by lactic acid bacteria (LAB) have been identified and studied in the last decades. Known as bacteriocins, these ribosomally synthesized peptides inhibit the growth of a wide range of bacterial species through numerous mechanisms and show a great variety of spectrum of activity. With their great potential as antimicrobial additives and alternatives to traditional antibiotics in food preservation and handling, animal production and in veterinary and medical medicine, the demand for bacteriocins is rapidly increasing. Bacteriocins are most often produced by fermentation but, in several cases, the low isolated yields and difficulties associated with their purification seriously limit their use on a large scale. Chemical synthesis has been proposed for their production and recent advances in peptide synthesis methodologies have allowed the preparation of several bacteriocins. Moreover, the significant cost reduction for peptide synthesis reagents and building blocks has made chemical synthesis of bacteriocins more attractive and competitive. From a protein engineering point of view, the chemical approach offers many advantages such as the possibility to rapidly perform amino acid substitution, use unnatural or modified residues, and make backbone and side chain modifications to improve potency, modify the activity spectrum or increase the stability of the targeted bacteriocin. This review summarized synthetic approaches that have been developed and used in recent years to allow the preparation of class IIa bacteriocins and S-linked glycopeptides from LAB. Synthetic strategies such as the use of pseudoprolines, backbone protecting groups, microwave irradiations, selective disulfide bridge formation and chemical ligations to prepare class II and S-glycosylsated bacteriocins are discussed.