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The engineering of the surface morphology and the structure of the thin film is one of the essential technological assets for regulating the physical properties and functionalities of thin film-based devices. This study presents an easy and handy approach to tailor the surface structure of epitaxial thin films utilizing low-energy ion beam. Here, we investigate the evolution of the surface structure and magnetic anisotropy (MA) in epitaxial Fe/MgO (001) model systems subjected to multiple cycles of ion beam erosion (IBE) after thin film growth. The growth of Fe film occurs in the form of three–dimensional islands and exhibits intrinsic biaxial MA. Following a few cycles of IBE, an induced uniaxial magnetic anisotropy leads to a split in the hysteresis loop, and the film displays almost uniaxial magnetic switching behavior. More distinctly, we present a clear and conclusive evidence of (2 × 2) reconstruction of the Fe surface due to the atomic rearrangement by IBE. Furthermore, 57Fe isotope sensitive nuclear resonance scattering measurement provides insight into the depth-resolved magnetic information due to the modified surface topography. We also demonstrate that thermal annealing can reversibly tune the surface reconstruction and induced UMA. The feasibility of the IBE technique by adequately selecting IBE parameters for surface structure modification has been highlighted apart from conventional tailoring of the morphology for the tuning of UMA and introduces a new dimension to our understanding of self-assembled surface morphology evolution by IBE. [ABSTRACT FROM AUTHOR]

High-strength steels (HSSs) have been gaining increasing attention in recent years because of their potential application for lightweight structures. Hybrid structural steel I-sections, featured by dissimilar strength grades for constitutive plates, provide a more economical solution to suit bending loading scenario. This study conducted experiments on nine I-sections with Q690 flange plates under four-point loads, incorporating three different web strength grades including Q690, Q460, and Q355. Furthermore, the local buckling behavior of representative I-sections with various section geometries was analyzed using a validated numerical method to understand the role of web strength grade. Test and numerical analysis results revealed that the section with web steel in the strain hardening stage exhibited different levels of ductility among specimens with different strength webs. It was also observed that earlier yielding or inelastic buckling of the lower strength web plate in hybrid I-sections affects the local buckling behavior of I-girders, in terms of moment resistance and rotation capacity. In addition, the initial local imperfection mode used in numerical analysis was found to affect the rotation capacity of I-girders, but the effect of web strength grade remains consistent among I-sections with the same local buckling deformation mode. This study provides further insights into the local buckling behavior of hybrid I-sections subjected to uniform bending, laying the foundation for further development of design methods. [ABSTRACT FROM AUTHOR]

Aiming at the high-speed railway (HSR)-China Railway Track System III (CRTS III) slab ballastless track (SBT)-simply-supported bridge system, the mapping relationship between girder deformation and rail deformation had been deduced theoretically, and then, the additional irregularity of the rail was obtained. A dynamic model of the high-speed train-track-bridge (TTB) coupling system was established according to existing theory on the high-speed TTB dynamic interactions. Combined with the mapping relationship, taking the superposition of the additional irregularity and the random irregularity as excitation, the dynamic response of two train models (CRH2 and ICE3 trains) was analysed by using the high-speed TTB coupling system model. The recommended thresholds of girder deformation were given based on running safety and ride comfort indicators. The results show that the sensitivities of the two train models exposed to girder deformation were different, and the CRH2 train was more sensitive to the lateral girder deformation. The non-uniform dislocation deformation of multiple girders exerted a slightly more significant effect on the dynamic characteristics of two train models than the dislocation deformation of single girder. Under the same amplitude of girder deformation, the influences of vertical girder dislocation and vertical girder rotation on the running safety and ride comfort of trains were significantly greater than that of lateral girder dislocation and lateral girder rotation. Acceleration and wheel-rail force increase rapidly in the area of girder deformation. To guarantee running safety and ride comfort of trains, this paper proposes suggested values for girder deformation thresholds. [ABSTRACT FROM AUTHOR]

The key to understanding the shear failure mechanism of prestressed concrete girders lies in how to properly deal with the combined effects of the applied load, the support reaction, as well as the prestressing force. This paper firstly conceptualizes a combined stress field model, which integrates these effects by manifesting several subfields to disclose the potential failure patterns at different locations in the short shear span. Then, shear tests of four full-scale pretensioned concrete T-girders with a height of 1.6 m and two kinds of shear-span-to-depth ratios were carried out. The test results showed that all the specimens failed in a web-crushing pattern near the support accompanied by a bond-slip of the deflected strands. By analyzing the deviated compression subfields in the highly stressed webs and introducing a failure criterion for cracked concrete, the ultimate shear strength of pretensioned concrete girders was formulated. Finally, the shear strength evaluated by the proposed formula and by some other design codes were compared, and it was proved that the results of the proposed model were closer to the test. [ABSTRACT FROM AUTHOR]

Steel plate girders are susceptible to web buckling due to slender web. This phenomenon creates an undesirable failure mode and limits their ultimate load capacity. The use of fiber-reinforced polymer (FRP) composite materials offers a good prospect of strengthening the slender web of plate girders to avoid web buckling. This paper presents the details of experimental testing of steel plate girders with nonrigid end posts. These girders were tested in three-point bending. The end shear panels of the girders were strengthened by glass FRP (GFRP) pultruded section stiffeners or glass fiber fabric composite. GFRP stiffeners were applied either vertically or along the compression diagonal in the shear panel. All strengthened panels failed by web shear buckling associated with a breakdown of the employed strengthening scheme. It was found that the shear capacity of the panel remained unchanged by replacing the steel stiffener with GFRP stiffeners in the end panel. The critical buckling load of the strengthened panels increased up to 44% compared to the unstrengthened panel. The shear capacities of the panels strengthened by the glass fabric composite and diagonal GFRP pultruded section were the highest and similar to each other. Both these panels resisted a 50% larger shear compared to the unstrengthened panel. The positions of the plastic hinges in all tested panels were the same due to the same ratio of panel length and depth of the web. [ABSTRACT FROM AUTHOR]

Road infrastructure development in Indonesia has increased the use of long-span prestressed concrete I-section (PCI) girders for bridge structures. However, these girders have instability issues during construction that resulted in multiple failures between 2017 and mid-2018. To address this problem, engineers compiled a standard guideline for erecting long-span PCI girders that includes three recommendations: a lifting point or lifting frame, a dapped-end girder, and artificial stiffeners. In late 2022, despite the initial effectiveness of the guideline, a video revealed that PCI girders were still vulnerable to failure despite strict adherence to the guidelines. A subsequent study reviewed the guidelines and revealed that not all the guidance was effective. The study emphasized the importance of standardized bracing at the supports. Therefore, it is necessary to revise and improve the guidelines to prevent similar failures in the future. Practical Applications: The process of erecting long-span prestressed concrete I-section (PCI) girders, which are more than 40 m long, is risky and can lead to toppling and collapsing. The main cause of this risk is the presence of lateral imperfections, which are limited to length or span of the girder (L)/500 (maximum) due to construction tolerances and the lateral stiffness being relatively small. Therefore, the process of erection must be carried out carefully and purposefully. To reduce the risk of accidents, a standard guideline for erection (SGE) was created. However, although the SGE (2018, 2021) has successfully reduced accidents, failures still happen. There are weaknesses in the SGE that need to be corrected. There are two critical risk stages during the erection of a PCI girder: the hanging and seated conditions. Using a lifting frame, according to the SGE (2018, 2021), is correct for the hanging stage. However, the seating procedure in the SGE needs improvement. It is vital to ensure that the strength of the bracing at the supports is standardized and installed correctly before removing the lifting crane. The reasons for this recommendation are explained in this paper. [ABSTRACT FROM AUTHOR]

In the degradation evaluation process of the crane girder structure under moving loads, the complex vibration response and low accuracy of health index standards are the main factors limiting the performance of the evaluation method. A method for identifying and evaluating damage to crane girder structures under moving loads has been proposed. In this method, optimized empirical wavelet transform (EWT) is used for decomposing the vibration signal of the crane girder structure to obtain sensitive components. A health indicator based on power spectrum maximum sequence is constructed by combining structural vibration simulation and response characteristics analysis under moving loads. A degradation index acquisition scheme based on an optimized sparse autoencoder is proposed, which utilizes a simulated annealing algorithm to optimize the model parameters of the sparse autoencoder. The effectiveness of the proposed method is verified through girder structure crack tests under moving loads. [ABSTRACT FROM AUTHOR]

Steel‐concrete composite box girders offer notable advantages such as high stiffness, excellent torsional performance, and light self‐weight, making them prevalent in large‐span bridges, particularly in cable‐stayed configurations. However, a persistent challenge arises from the shear lag effect in the concrete slab within the flanges induced by shearing interactions between the webs and flanges. Limited attention has been devoted to investigating the experimental and theoretical aspects of shear lag in long‐span cable‐stayed bridges with twin box‐shaped composite girders. This research addresses this gap by designing a segmental scale twin box‐shaped composite model specimen to simulate the cable spacing of the main girder in a cable‐stayed bridge, specifically targeting the shear‐lag effect. The study successfully captures the non‐uniform distribution of cross‐sectional strain in the top concrete slab. Subsequently, analytical strain solutions for the composite girder under mid‐span concentrated load and axial load are derived using the energy variation method. The theoretical model's applicability is then calibrated against experimental results. The investigation extends to the in‐situ testing of the Chibi Yangtze River Bridge, the world's largest steel‐concrete composite girder cable‐stayed bridge, boasting a main span of up to 720 m. An established finite element (FE) analysis model for the Chibi Yangtze River Bridge simulates the transverse stress distribution under typical construction conditions of CC6. Comparative analyses between the simulated results, calculated values from elementary beam theory, and the theoretical model against field‐measured values reveal that the FE model provides a more accurate estimation of the shear lag effect in the concrete slab. Notably, the FE model effectively reflects the bridge's characteristics and serves as a baseline for subsequent studies. This comprehensive investigation contributes significantly to the understanding and analysis of shear lag phenomena in twin box composite girders of cable‐stayed bridges. The integration of experimental, analytical, and construction site validations establishes robust tools for engineering design and the construction of safe and serviceable cable‐stayed bridges. The research augments knowledge regarding shear lag behavior and underscores the necessity to appropriately consider its effects in bridge analysis and design. [ABSTRACT FROM AUTHOR]

The bridge models reconstructed from unmanned aerial vehicle (UAV) images via photogrammetry are often reported to have quality issues (e.g., high noise, insufficient resolution and precision loss) and thus restrict their application in bridge inspection. To address this problem, this paper proposes a novel Building Information Model (BIM)-based 3D path planning method for improving the quality of photogrammetric bridge models by optimising the UAV flight plan. This method firstly uses a simple BIM model as input and considers inspection and photogrammetry requirements to generate effective UAV viewpoints. Then it adjusts inaccessible UAV viewpoints that are in occupied space or cannot meet the flight safety rules. Finally, a feasible flight trajectory is generated through all valid viewpoints. To evaluate the performance of the proposed method, two prototypes were developed to automate the path planning and on-site image acquisition, respectively, and were tested on a real girder bridge. The results showed that, compared with the common UAV flight plan used in current practice, the proposed method could: (1) generate a more precise bridge model with fewer noise points and higher visual quality to support damage detection; and (2) significantly improve the efficiency of photogrammetric 3D bridge reconstruction with reduced human interventions in image collection and processing. [ABSTRACT FROM AUTHOR]

Copyright of Transportation Science & Technolgy is the property of Transportation Science & Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Transportation Science & Technolgy is the property of Transportation Science & Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A full-scale hybrid beam consisting of a UHPC slab and FRP truss girder was fabricated. The novel side plate FRP joint characterized with improved loadcarrying capacity, stiffness, and preferred failure mode along with the tailored shear connector validated in the previous studies of the authors were adopted. Its flexural performance was characterized and compared with that of hybrid beams employing NC or UHPC slab but I-profile girder. The failure of the proposed hybrid beam subjected to bending was pseudo ductile whereas those of the other two hybrid beams were brittle. The load-carrying capacity and stiffness of the proposed hybrid beam outperformed the other two hybrid beams with comparable dimensions and material properties. [ABSTRACT FROM AUTHOR]

The guideway’s alignment deviations are of concern when assessing the vibrations of high-speed maglev transportation systems. Among these, the deformation of the guideway due to solar thermal effects is a critical issue impacting the operational efficiency of a maglev train running on a guideway system. To address this issue, this study integrates solar radiation, shadow masking, heat convection and radiative heat transfer to present a thermal-mechanical coupling model for investigating the temperature-deformation field of guideway girders. Meanwhile, on-site measurements are conducted to confirm the feasibility of using temperature field distribution to estimate the thermal deformation of guideway girders. A solar-thermal field formula suitable for a maglev vehicle-guideway system is proposed to estimate the temperature field distribution on the guideway girders by referencing the formulas in the known specifications. Finally, this paper introduces an electromagnetic feedback controller that adjusts the maglev forces using real-time thermal deformation data to mitigate the effects of solar thermal-induced guideway deformation on the maglev vehicle-guideway system, demonstrating that the dynamic response of a maglev train is significantly influenced by the thermal deformation of guideway girders due to sensitive variations in levitation gaps. [ABSTRACT FROM AUTHOR]

Copyright of Machine Tool & Hydraulics is the property of Guangzhou Mechanical Engineering Research Institute (GMERI) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The wind-resistant performance of cable-stayed bridges under construction deteriorates sharply as the cantilever length increases, and the arrangement of the temporary pier is an effective measure to improve aerodynamic stability. To investigate the effect of the temporary pier on buffeting response of a long-span three-tower cable-stayed bridge under construction, the nonlinear buffeting analysis and wind tunnel test of aeroelastic model methods are adopted in this paper. The influence of the type and arrangement positions of temporary piers on mean wind response and the nonlinear buffeting response of double-cantilever construction are studied, and the arrangement of the temporary pier is optimized based on the buffeting response. The results show that the reduction rates of the RMS of the torsional moment at the tower bottom and the lateral buffeting displacement at the girder end with the rigid pier are 35.6% and 59.2% compared to those without the temporary pier. Further, the buffeting response will decrease as the distance between the rigid pier and the tower increases in the state. On the contrary, in the double-cantilever construction state before the constraint of temporary piers, the buffeting response will become significant as the distance increases. Therefore, it is necessary to consider the buffeting response under two construction states when optimizing the arrangement position of the temporary pier. [ABSTRACT FROM AUTHOR]

This paper presents a comprehensive finite element analysis (FEA) of pre-stressed Ultra High-Performance Concrete (UHPC) girders, showcasing intricate structural behaviors under various loading conditions. Utilizing advanced finite element modeling techniques, the study accurately simulates the flexural response of UHPC girders, integrating experimental results from large-scale laboratory tests conducted by researchers at the Turner-Fairbank Highway Research Center. This paper shows the effectiveness of simulating pre-stressing forces via initial equivalent temperature load with relatively accurate stress and strain predictions. The paper also delves into the moment–deflection relationships at critical stages, such as first concrete crack appearance, yielding, and strain localization, to capture the non-linear behavior of UHPC girders under pre-stressed conditions. Additionally, crack propagations were characterized by investigating the damage in tension (DAMAGET) plots. In summary, the results of the finite element model agree well with the experimental observations. Moreover, this study not only demonstrates the effectiveness of FEA in accurately simulating the complex structural behaviors of UHPC girders but also highlights its broader applicability to the design and analysis of other girder types, offering valuable insights compared to ordinary concrete beams. [ABSTRACT FROM AUTHOR]

A new consolidation system for prestressed reinforced concrete (PSRC) beams of girder bridges is presented and evaluated. The system consists of two arch-shaped steel trusses placed alongside the lateral faces of the beam to be consolidated. The arches develop longitudinally along the entire span of the beam and in elevation using the available height of the PSRC cross-section. The consolidation system is characterised by its own external constraints, independent from those serving the pre-existing element. The efficiency of the system with respect to variable parameters is examined, focusing on the ratio between the load discharged by the consolidation system and the total applied load. Referring to a case study, consolidation of a PSRC beam adopting the proposed system is compared with the usually adopted external prestressing technique. The cross-sectional properties of the steel arch-shaped trusses are defined by means of a structural optimisation process using a genetic algorithm to identify the minimum steel consumption. Finally, a preliminary cost–benefit analysis is performed for the proposed solution and compared with other commonly adopted techniques. [ABSTRACT FROM AUTHOR]

Although ultra-high-performance concrete (UHPC) is one of the promising materials for precast bridge girder applications due to its advanced properties and durability, its implementation in the precast industry is subject to several potential concerns. To support implementation, this paper presents the development of nonproprietary UHPC mixtures for precast, pretensioned UHPC bridge girder applications. The nonproprietary UHPC mixtures were developed using materials commonly available in the Texas precast industry, with the additional requirement of obtaining a compressive strength of 12 to 14 ksi (83 to 97 MPa) within 24 hours without any heat treatment while maintaining the current precast, pretensioned bridge girder fabrication practices. The fresh, hardened, and durability properties of both laboratory- and plant-made UHPC mixtures were investigated. The research results show that the selected nonproprietary UHPC mixture developed in a laboratory setting can be successfully produced in a precast plant setting with comparable properties. [ABSTRACT FROM AUTHOR]

With the expanding application of lightweight wooden structures in modern construction, the load-bearing capacity of ordinary triangular single-span wooden trusses limits the applicability of lightweight wooden structures. As a result, triangular multi-span wooden trusses have emerged to replace single-span wooden trusses. In practice, multi-span wooden trusses are composed of multiple single-span lightweight wooden trusses, with connections between members using metal plates, a field that has been relatively well researched. However, connections between spans are primarily made with nails in actual engineering, and there has been little research on the use of wooden pins to connect multi-span wooden trusses. To study the mechanical performance of multi-span wooden trusses connected by wooden pins, this paper innovatively combines existing equipment with a self-designed pulley assembly device to conduct a continuous static full-scale loading test on double-span wooden trusses connected by wooden pins of three different diameters. We comprehensively evaluate which type of wooden pin is more suitable for triangular multi-span wooden trusses. The results indicate that the 16 mm diameter wooden pin provides the best energy dissipation performance for connected beam trusses. The 20 mm diameter wooden pin offers the best performance stability. The 20 mm diameter wooden pin also demonstrates a good load-bearing capacity and resistance to deformation. Overall, the 20 mm diameter wooden pin exhibits the best connection performance in triangular beam trusses. [ABSTRACT FROM AUTHOR]

Copyright of Railway Construction Technology is the property of Railway Construction Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Railway Construction Technology is the property of Railway Construction Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The blast resistance of a typical two-lane steel girder highway bridge structural system was modeled using a nonlinear finite-element approach that considered material damage, fracture, and separation. Critical blast scenarios were based on field observations of terrorist attacks on bridges in Iraq, while system failure was defined in terms of practical emergency serviceability criteria used on actual blast-damaged bridges. The blast resistance of various design parameters was assessed, including the number of girders, deck concrete strength, reinforcement ratio, slab thickness, girder and reinforcement yield strength, girder sectional dimensions, and pier column width. The presented approach uniquely quantifies structural system blast resistance in terms of the charge weight that can be applied at different locations until failure. A sensitivity analysis was conducted to determine the most influential design parameters. It was found that system blast capacity was primarily influenced by the number of girders and girder yield strength, while additional significant parameters were deck compressive strength, deck thickness, web stiffener width, and girder depth. Secondary parameters were deck reinforcement ratio, girder flange, and web thickness, while deck reinforcement yield stress was found to be insignificant. Based on the results, recommendations for improving blast resistance are provided. [ABSTRACT FROM AUTHOR]

Steel bridge designers and erectors primarily rely on approximate methods, such as 1D line girder analyses and 2D grid analyses. For curved or skewed bridges, this can give erroneous indications of the structure's true behaviour. Refined methods of analysis, such as 3D shell modelling, aim to bring a significant change in the practice of bridge engineering. By moving the industry away from simplistic design assumptions, refined analysis methods lead to more accurate, less conservative results, which in turn brings true benefits such as improved structural safety and increased economy. In this paper, several case studies on curved plate girder and tub girder bridges are presented, which cover the full bridge life cycle, from erection of the steel structure and placement of the concrete deck, down to live load analyses using influence surfaces and load rating. The case studies will be modelled with mBrace3D, a dedicated FEA software for curved steel bridges. [ABSTRACT FROM AUTHOR]

The new railway line connecting Luxembourg and Bettembourg crosses the A3 highway at a steep angle (19.5°) with the bridge called OA14. The designed bridge is a bowstring structure with a single span of 186.85 meters. The bridge deck consists of two lateral metal box girders acting as a chord. The deck is a transversal filler beam, with spherical voids and lightweight concrete to reduce the structure's weight. The bridge features two inward‐inclined arches at 9°, which are doubled and serve as trusses. This significantly increases the stiffness of the arch whilst keeping the silhouette elegant. The deck follows the curved track alignment, the arches remain straight. Two times 12 hangers connect the arches to the girders, they are made of CHS profiles of S450H quality. This article gives an overview of the structure and its construction. It then gives a more detailed insight in the design of the hangers, especially the hanger‐girder connections. [ABSTRACT FROM AUTHOR]

Copyright of Coal Geology & Exploration is the property of Xian Research Institute of China Coal Research Institute and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper presents the implications of a hydrocarbon fire on the behavior of bridge girders prestressed with either steel strands or carbon fiber-reinforced polymer (CFRP) tendons. Stemming from a recent bridge fire that occurred in Lakewood, CO, numerical investigations are conducted employing a computational method called agent-based modeling to understand the intricate responses of these girders under thermomechanical loading. As the convection and radiation of surroundings are transformed to conductional thermal energy, the temperature of girder concrete rises, and the internal temperature differentials dwindle over time. Thermally induced damage in the prestressing elements is a function of distance from the surface heat. When loaded without thermal distress, the moment-carrying mechanism of the steel- and CFRP-prestressed girders is analogous; however, with the presence of heat, the development of lever arms and tensile strains of the girders demonstrates palpable differences. The maximum usable strains of the steel and CFRP vary with the degree of thermal exposure, thereby dominating the load-carrying capacity of the girders. From a design perspective, no evidence is noted to distinguish the performance of the steel- and CFRP-prestressed girders under service loadings, and contrary to commonplace notion, their fire ratings are found to be comparable because of sequential heat transfer. [ABSTRACT FROM AUTHOR]

Segmentally assembled bridges are increasingly finding engineering applications in recent years due to their unique advantages, especially as urban viaducts. Vehicle loads are one of the most important variable loads acting on bridge structures. Accordingly, the influence of overloaded vehicles on existing assembled bridge structures is an urgent concern at present. This paper establishes the finite element model of the segmentally assembled bridge based on ABAQUS software and analyzes the influence of vehicle overload on an assembled girder bridge structure. First, a finite element model corresponding to the target bridge is established based on ABAQUS software, and the load is controlled to simulate vehicle movement in each area of the traveling zone at different times. Second, the key cross-sections of segmental girder bridges are monitored in real time based on the force characteristics of continuous girder bridges, and they are compared with the simulation results. Finally, a material damage ontology model is introduced, and the structural damage caused by different overloading rates is compared and analyzed. Results show that the finite element modeling method is accurate by comparing with on-site measured data, and it is suitable for the numerical simulation of segmental girder bridges; Dynamic sensors installed at 1/4L, 1/2L, and 3/4L of the segmental girder main beams could be used to identify the dynamic response of segmental girder bridges; The bottom plate of the segmental girder bridge is mostly damaged at the position where the length of the precast beam section changes and the midspan position. With the increase in load, damage in the direction of the bridge develops faster than that in the direction of the transverse bridge. The findings of this study can guide maintenance departments in the management and maintenance of bridges and vehicles. [ABSTRACT FROM AUTHOR]

The existence of water-filled barriers alters the cross-sectional shape of the main girder, which may lead to vortex-induced vibrations (VIVs) in suspension bridges. However, the mechanism and occurrence conditions of VIVs in the main girder that is affected by water-filled barriers are still unclear. To this end, this study investigates the effect of water-filled barriers on the VIV performance of suspension bridges. The evolution of the vortex structure during one VIV cycle and the corresponding pressure variations, including the average and fluctuating values on the surface, were analyzed. Additionally, the spatiotemporal distribution of the surface pressure was studied using proper orthogonal decomposition (POD). The results show that VIV occurs in the main girder when the height of the water-filled barriers exceeds a threshold value of 0.317. Moreover, a significant negative pressure vortex occurred when the barriers were installed. The vortex underwent the following distinct phases in one VIV cycle: generation, separation, reattachment, and shedding. However, the negative pressure vortex behind the barrier did not vary substantially when the water-filled barriers were installed without VIV. Additionally, the average pressure on the surface of the main girder remained constant regardless of the occurrence of VIVs. In the presence of VIVs, the pressure fluctuations became much more pronounced and were mainly concentrated on the top surface and leading edge of the main girder. Additionally, the dominant modes of the pressure variations correlated with the evolution of the vortices and pressure distribution. [ABSTRACT FROM AUTHOR]

Active flap is an advanced aerodynamic measure that can effectively increase the flutter performance of flexible bridges, but its control mechanism is still confusing due to the complex phenomenon of aerodynamic interference between the deck and flaps. This study proposes an assessment method to clarify the flutter control mechanism of the deck‐flap system by the computational fluid dynamics (CFD) method and quantifies the contribution of the aerodynamic damping from the active flaps. It is found that the composition of active flap to the improvement of flutter performance can be divided into torque effect and interference effect. Also, the torque effect of the flaps mainly provides equivalent positive aerodynamic damping ratio under effective control parameters, but the interference effects with the deck and two flaps are not the same, and the mutual interference effect between the two flaps is very weak. For the purpose of investigating the aerodynamic interference influence between the girder and flaps, the research further discussed the impact of the distance between the deck mounting position and the bridge girder on the system flutter performance. As the distance increases, the flutter performance of the system gradually improves. Also, the torque effect of the leading and trailing flaps will increase with distance. However, the interference effects of the flaps on both sides show different rules. In total aerodynamic damping ratio of the deck‐flap system, the torque effect accounts for about 70% and interference effect accounts for 30%. As the distance increases, the torque effect gradually becomes stronger and the interference effect gradually weakens. [ABSTRACT FROM AUTHOR]

AbstractWhen a train traverses a curved bridge, it inherently tends to shift laterally outward. To counteract this propensity, the strategy of track superelevation is employed. After earthquake, curved bridges may exhibit diverse degrees of residual deformation. The precise failure mechanisms that compromise train safety and passenger comfort during transit over curved bridges, particularly under the combined influence of residual deformation, centrifugal force, and track superelevation, remain not entirely comprehended. A comprehensive system integrating trains with curved track-bridges is developed to examine the impact of girder end misalignments on residual track irregularities. The analysis concentrated on the dynamic time-history responses of trains traversing bridges featuring girder misalignments, exploring a range of amplitudes, train velocities, and curve radii. The findings revealed significant variances in the dynamic train responses, especially in lateral acceleration and the Nadal index, when contrasting centripetal and centrifugal girder side misalignments. Furthermore, it is discerned that lateral misalignment at the girder ends markedly affects train lateral acceleration and the Nadal index, with a relatively minor influence on other dynamic response metrics. Finally, the thresholds for misalignment deformation were summarized, for curve radii of 800, 1000, and 1200 meters, the comfort deformation thresholds at 100 km/h are determined to be 23, 23, and 20 mm respectively, while the safety deformation thresholds are found to be 26, 30, and 38 mm respectively. At a speed of 120 km/h, the comfort deformation thresholds for the same curve radii are 18, 18, and 15 mm, with the safety deformation thresholds at 12, 15, and 21 mm. [ABSTRACT FROM AUTHOR]

A series of bridge overturning accidents in recent years indicates that single-column pier bridges are susceptible to overturning failure. However, the traditional calculation method was incapable of ensuring an accurate prediction of the ultimate overturning capacity, which may lead to serious consequences in engineering practice. In this work, an analytical method was proposed based on the identified failure mechanisms. The forensic survey was first carried out on two typical overturning cases, and the findings of the surveys were summarized into three typical overturning failure modes and their corresponding criterion for failure evaluation. Further, the analytical method was proposed on the assumption that overturning of the girder consists of rigid and deformable body rotation and characters including radial bending and torsional deformation were considered. The method was later validated by the field data of the overturning cases. Besides, factors influencing the results were also compared and analyzed. The results demonstrate that, in comparison with the conventional calculation method, the proposed approach more effectively accounts for spatial parameter variations and nonlinear factors during girder rotation, thereby aligning better with the actual overturning process. [ABSTRACT FROM AUTHOR]

To provide convenient access to service ducts, beam and girder web openings are very prevalent in practice. The insertion of a reinforced concrete (RC) beam into the web, however, reduces the stiffness and strength of the beam because of the local cracking around the aperture. The employ of fiber-reinforced polymer (FRP) laminas in general and not a specific type of them for reinforcing the holes was showed in this paper including their dimension and some design parameters change, such as the number and placement of (FRP) sheets near the opening. The experimental work was presented by comprised the testing of ten reinforced concrete beams, four of them were tested without reinforcement, five of which had (FRP) sheets around the opening for reinforcement, and the remaining beam was solid. The (FE) program consists of ten beams were modelled by using Abaqus, one of them was control solid beam and other nine beams were with hollow. The load-deflection relationships were evaluated before failure, and crack patterns were obtained and compared with the experimental results available. The numerical and experimental results agreed well. Reinforced concrete beams are the cornerstone of modern infrastructure, carrying heavy loads and forming the basic structure of buildings and structures. However, these beams may be damaged or deteriorated over time due to multiple factors such as corrosion, overload, moisture, and fire. In addition, the need to make modifications or openings in these beams for maintenance or service installation purposes may negatively affect their load-bearing capacity. To overcome these challenges, modern techniques have emerged to strengthen concrete elements, the most important of which is the technique of strengthening concrete with fiber reinforced polymer (FRP). This technique is highly effective in increasing the load-bearing capacity of concrete beams, improving their performance under different loads, and extending their service life. A brief critique of the limitations of existing studies should be included to highlight the significance of the present work. Inadequate studies on the interaction between FRP and concrete: There are still gaps in our understanding of the interaction between FRP and concrete at the microscopic level, which affects the accuracy of computational models. The research focused on the behavior of FRP-reinforced concrete hollow core beams under different loads, filling a gap in previous research. The research combined computer simulations and laboratory tests to ensure the accuracy of the results and provide a comprehensive picture of the behavior of the beams. The research identified the best methods for applying FRP sheets to improve the load-bearing capacity of beams around openings, providing practical guidance for engineers. [ABSTRACT FROM AUTHOR]

Lateral torsional buckling reduces the moment capacity of steel I-girders. To redress this weakening, one approach is to replace the conventional plate flange with a rectangular tube, which has higher lateral stiffness and is thus helpful to resist lateral buckling. At the same time, web openings are introduced to enable services to pass through, but this causes a reduction in strength. Girders with tubular flange plus web openings have not yet been discussed in the literature. In this paper, finite-element method modelling is used to fill this gap, studying different slenderness classifications, as well as parameters such as size of web openings, spacing and location. The results for a solid web are found to be more comparable to the Eurocodes for steel structures than the American Institute of Steel Construction codes, enabling good prediction of the flexural capacity. By introducing web openings, the flexural capacity is reduced by 10–20%, closer to the higher side for openings with large diameters located near the compression flange. Openings with an oval shape have less reduction in strength, whereas the square is unfavourable. Tubular flange girders, even if perforated, provide flexural strength enhancement and a considerable reduction in material compared with plate flange girders. This section also behaves better in relation to carbon dioxide emissions. [ABSTRACT FROM AUTHOR]

The mechanical characteristics of segmental joints are pivotal in defining the comprehensive stress behavior of prefabricated assembled cover beams. In this research, direct shear tests were conducted on dry key‐tooth joints, and acoustic emission technology was employed for monitoring purposes. The shear failure mechanism was explored under a range of influential parameters. Building upon these observations, the study delved into the mechanical response of joints within segmental cover girders subjected to concurrent bending and shear forces. Specimen K‐3‐3 exhibited a higher shear carrying capacity compared to other specimens, indicating that the shear resistance of dry joints proportionally increases with the height of the specimen and the strength of the concrete. The carrying capacity of Specimen K‐4 was marginally lower than that of Specimens K‐3‐1 and K‐3‐2, suggesting that increasing the number of keys does not significantly impact the shear resistance of dry joints. Notably, Specimen K‐3 demonstrated exceptional shear carrying capacity, exhibiting minimal relative slip during failure, and streamlined the casting process. Consequently, these dry joints featuring large key teeth are deemed more appropriate for use as shear connectors in precast concrete segmental cover beams. Crack patterns in large key tooth precast concrete segmental cover beams propagate along the joints. A damage evolution model for the specimens, based on spatial b‐values and T‐values, visually depicts the damage extent in large key tooth precast concrete segmental cover beams. This model demonstrates excellent agreement with experimental results and provides a solid foundation for theoretical research and practical applications of large key tooth precast concrete segmental cover beams. [ABSTRACT FROM AUTHOR]

This research studies shear strengthening performance for Normal Concrete (NC) beams employing Engineered Cementitious Composite (ECC) reinforced with Galvanized Welded Wire Mesh (GWWM) in conjunction with/without a prestressing system. Six full‐scale Reinforced Concrete (RC) beams were experimented under static monotonic loading at critical shear span zone up to collapse. The investigated factors were: the type and technique of strengthening, materials used for strengthening, and size and configuration of shear reinforcement. Two techniques were introduced: ECC layer reinforced with GWWM and pretensioned steel bars recovered by ECC with one GWWM. GWWM with and without pretensioned steel bars were delivered as shear reinforcement for strengthening. Vertical and inclined steel bars were the two configurations selected for the prestressing technique for suppressing shear stress. The study was discussed through the experimented beams' crack load and pattern, collapse mode, elastic stiffness, absorbed energy, initial cracking load, and ultimate load, along with the corresponding defection. Experimental results showed that both exploited techniques could govern crack patterns, enhance the failure mode, and upgrade ultimate loading capacity up to 52%. Finite element models were built up, simulating those strengthened with an ECC covering layer augmented with GWWM extracting a model with an error of about 3%. [ABSTRACT FROM AUTHOR]

The structural elements of buildings have recently required the development of efficient design solutions due to increased dynamic and thermal loads. The main solution for improving the efficiency of such elements involves creating lightweight non-uniform beam and arch structures from alloyed steel, which has better mechanical characteristics. The most promising approach is the use of welded beams and arches with perforated partitions and composite beams, which are often used together, for instance, as structural elements of cylindrical shells. The development of an effective cross-sectional shape for perforated beams and crane girders is considered, taking into account the strength, local stability, resistance to flat bending, and fatigue deformation. It has been shown that the effective form for perforated beams is a box-shaped structure made of perforated shvellers. Calculations for selecting a rational design from the assortment of hot-rolled shveller profiles have demonstrated that a significant reduction in the weight of the structure can be achieved by using the proposed cross-sectional shape. An evaluation of the fatigue strength of composite metal crane girders operating in harsh conditions has shown the effectiveness of using hot-rolled I-beams as their upper flange, as well as the necessity of using hot-rolled I-beams to ensure strength in their lower part. When choosing the rational parameters of an arch design, multiple recalculations of its bending with respect to technological cutouts in the thickness are necessary; hence, simplified calculation schemes are commonly used. Some authors simplify this process by replacing an arch with a cutout with a solid arch reduced in height by the cutout radius. We have shown that this model does not accurately describe the actual distribution of forces and displacements, leading to inadequate results. We have developed a simplified methodology for the preliminary calculation of a circular arch with a cutout, which includes correction coefficients calculated by us. A calculation of the flat stress–strain state of an elastic circular metal arch with a central semicircular cutout under various ratios of design parameters and uniform external pressure was conducted. A dependence of the stress concentration coefficient at the cutout's apex on the ratio of the cutout radius and arch thickness was obtained. These results can be generalized for reinforced non-uniform shells and for the fuzzy application of external influences. [ABSTRACT FROM AUTHOR]

Due to the existence of the upstream and downstream gap, the flow dynamics around a separated triple-box girder becomes quite complex. This work explores the flow dynamics around a triple-box girder, i.e., multiple separation–reattachment effect, shear layers' impingement–rebound effect, separated- and double-shear-layer instability, etc. Three angles of attack (AOAs), i.e., 0°, +5°, and −5°, were considered for investigating the vortex dynamics of a classical triple-box girder, and the Reynolds number (Re) was set at 1.05 × 10 4 . The time-averaged and instantaneous flow fields as well as the distribution of the fluctuating magnitude are discussed. The results show that, under 0°AOA, the upstream gap flow (flow in the upstream gap) is characterized by the shear layer impingement while intermittent vortex-shedding appears in the downstream gap. Time–frequency analysis and instantaneous flow fields reveal that the spectral intermittency is caused by oscillations of the lower shear layer. The different flow dynamics are analyzed in detail by the spectral proper orthogonal decomposition analysis. Under +5°AOA, the interactions of the shear layers in both gaps show weak periodicity, and the instability of the separated shear layer dominates the whole flow field. Under −5°AOA, the double-shear-layer instability dominates both gap flows. The periodical shedding vortices are observed simultaneously in both gaps with varied dominant frequencies. The complex impacts of the impingement–rebound effect as well as the essence of the "multi-frequency" phenomenon are also revealed. [ABSTRACT FROM AUTHOR]

The Π-type steel-concrete composite girder, a commonly used bridge deck composed of an upper concrete slab and two lower lateral I-side steel girders, often suffers from severe vortex-induced vibrations (VIVs). Herein, the VIV response and triggering mechanism of a Π-type girder are systematically investigated, by adopting 1:50 scale section model wind tunnel tests and flow-field numerical simulations. Afterward, several aerodynamic measures were designed to mitigate the significant VIVs present in the original section, and an effective measure composed of the G-shaped apron and lower central stabilizer plate was found. Numerical simulation results show that the Π-type girder's upper and lower surfaces both exhibit severe vortex shedding, and both contribute significantly to the occurrence of VIVs. Consequently, the aerodynamic measures introduced for the Π-type girder must be able to simultaneously improve the flowing bypassing situation around the upper and lower surfaces of the section, and the G-shaped apron and the lower central stabilizer plate could both accomplish this simultaneously. The results show that the VIV suppression effect of this G-shaped apron combination measure is greatly affected by the height of the G-shaped apron's vertical plate and the height of the lower central stabilizer plate. Only both of them to a certain height, this measure can entirely prevent the Π-type girder from VIVs. After shape optimization, a G-shaped apron combination aerodynamic measure that can eliminate completely the Π-type girder's VIVs at low damping ratios of about 0.5% is proposed, of which the vibration-suppressing effect was verified by wind tunnel testing of 1:20 section model. [ABSTRACT FROM AUTHOR]

Due to the asymmetrical cross section of long-span rail-cum-road twin-girder bridges, the aerodynamic interference effect and flow characteristics of the twin girders in the gap are complicated. To study the influence of spacing on their aerodynamic characteristics, section model wind tunnel tests were conducted on a long-span rail-cum-road twin-girder cable-stayed bridge. This study considered the two conditions of bare and completed girders and the two inflow directions of 0° and 180°, with a spacing ratio range of L/Br = 0.1–2.0, and tested the surface wind pressures of the twin girders. Their aerodynamic and flow characteristics were analyzed, and the influence of spacing on their aerodynamic interference was clarified. The results show that for asymmetrical twin girders, the spacing and direction of incoming flow are still the key factors affecting their wind pressure distribution and flow characteristics. Due to the asymmetry of twin-girder sections, the influence of spacing on the wind pressure distribution and flow pattern varies with different flow directions. Furthermore, the attachments to completed girders enhance the asymmetry, making the aerodynamic and flow characteristics more complex than those of bare girders. Finally, three flow patterns are summarized: the upstream girder lower surface wake acts on the downstream girder fairing lower surface, acts on its fairing upper surface, and acts at its fairing. [ABSTRACT FROM AUTHOR]

The fabrication process of pretensioned prestressed concrete (PC) girders involves temperature changes, which affect the effective prestress and mechanical properties of the girders. Currently, there is a lack of a holistic understanding and accurate calculation methods for the prestress variation due to temperature change (PVTC), leading to technical challenges in calculating effective prestress in pretensioned PC girders. This study investigates the PVTC in three stages considering the time-varying interaction between concrete and tendons, proposes a new method to consider the effect of a deviator on the PVTC of a bent tendon, conducts an experimental study to validate the theoretical analysis, and develops measures for reducing the PVTC. The results show that the presented method provides reasonable predictions of PVTC, and the PVTC of the girder with steam curing is up to 80.3 MPa. Based on the presented method, measures for reducing the PVTC are proposed. This study provides new insights into computing the PVTC and improves the design and fabrication of pretensioned PC girders. [ABSTRACT FROM AUTHOR]

In railway tracks, additional stresses occur in rails due to interaction between the rail and the bridge superstructure, which is a phenomenon known as track–bridge interaction (TBI). The additional rail stresses (ARSs) develop primarily as a result of temperature effect, vertical bending of bridge superstructure, and braking/acceleration of trains traveling over the bridge. One of the major parameters affecting the TBI response is the behavior of interface elements simulating the coupling between the bridge superstructure and the rail. In TBI analysis this coupling is defined by the so-called longitudinal resistance-displacement curves (RDCs). The present study deals with the longitudinal aspect of TBI though a numerical investigation. The numerical modeling approach was verified with available analytical solutions and data obtained from bridge monitoring. The primary interest was to illustrate how sensitive the TBI response is to changes in RDCs with both separate and sequential analysis approaches, which has not been investigated thoroughly earlier. The parametric study was extended to investigate the effects of expansion length and substructure stiffness, in addition to RDC type. For simply supported precast girder bridges, RDCs that are experimentally proven specific to ballastless railway bridges can be used as an economic alternative to those specified by provisions. [ABSTRACT FROM AUTHOR]

Direct resistance check by applying advanced numerical models is getting increasingly used for the design of steel slender plated structures. This method has to take into account the same uncertainties as traditional analytical design calculations and should ensure the Eurocode-based prescribed safety level. The application of the model factor gives the possibility to account for the model-related uncertainties. The current study focuses on the determination of the model factor for one specific failure mode, the patch loading resistance. Numerical model has been developed and validated based on laboratory test results. To evaluate the model uncertainties, physically possible modeling differences are introduced, and their effects are evaluated on the resistance. The final aim of the study is to determine the model factor for the analyzed girder type and failure mode based on statistical evaluation. [ABSTRACT FROM AUTHOR]

This research presents an experimental program for flexural strengthening of reinforced concrete (RC) full-scale girders with externally bonded carbon fiber–reinforced polymer (CFRP) sheets secured with fiber anchors. The testing program consisted of five RC T-girders strengthened with identical CFRP sheets anchored with different numbers of CFRP fiber bundles. The main objective of this study is to address the effectiveness of the CFRP fiber anchors in controlling premature failure of the CFRP sheets due to debonding. To evaluate the experimental results, a simplified design model was introduced to predict the effective CFRP maximum strain limit associated with a given number of fiber anchors in the shear span. The test results show that using CFRP fiber anchors significantly delayed the failure of the CFRP sheet beyond the classical intermediate crack (IC) debonding failure mode. In addition, the presented design model agrees reasonably well with the experimental findings as it pertains to the various numbers of anchors. Nevertheless, an anchor efficiency factor is proposed herein to reflect the fiber anchor group effect based on the experimental findings. Practical Applications: This paper presents an experimental program and a design model to capture the efficiency improvements of the response of carbon fiber–reinforced polymer (CFRP) strengthened full-scale reinforced concrete T-girders secured with increasing number of carbon fiber anchors along the shear span. Both the equivalent debonding strain and load capacity were improved owing to the use of increasing numbers of fiber anchors per shear span. This study showed that the ultimate failure of the girders can be controlled by the number of fiber anchors used to secure the CFRP sheets. Sectional analysis may not be strictly applicable once the progression of debonding starts. However, it is shown to capture a reasonably accurate measure of the maximum CFRP debonding strain without the need to resort to higher-order analysis that does not lend itself to design practice. [ABSTRACT FROM AUTHOR]

In this paper, the dynamics of an axially translating functionally graded cantilever beam (FGCB) with time-varying length are studied under environmental temperature variations. Firstly, the governing partial differential equation for the FGCB under different temperatures is established based on the Euler–Bernoulli beam theory. Secondly, the Galerkin discretization and the assumed mode method (AMM) are employed to derive the vibration equations for each mode. Then, the coupling effects of the axial translation motion and the bending deformation on the vibration response of the FGCB are analyzed through numerical simulation. The results showed that different initial lengths, velocities and accelerations can influence the dynamic response greatly. Moreover, the increase in temperature will increase the response amplitude and decrease the frequency of FGCB, but the increase in functionally gradient parameter will decrease both the amplitude and the frequency of the FGCB. Finally, the wavelet transform (WT) is utilized to perform a time–frequency analysis. It is found that the time-dependent frequency obtained by using WT is consistent with the first-order static frequency obtained theoretically. The variation of frequency with time can be obtained quickly and accurately by using WT. The results of this research are of great significance for the application of composite axially translating beams in practical engineering. [ABSTRACT FROM AUTHOR]

Corrugated steel web (CSW) sections are utilized worldwide in civil and mechanical engineering because of their advantages over flat sections, including enhanced lateral stability, a higher strength-to-weight ratio, improved energy absorption, and a reduced need for vertical stiffeners. The stability of such thin-walled structures becomes critical due to the small thickness of components and complex geometry. While lateral torsional buckling (LTB) can be avoided through lateral restraints, individual components of a girder, i.e. web and flanges, may undergo failure due to local instability. This paper focuses on summarizing the approaches for evaluating the local stability behavior of the flange and web sections. The review presents a holistic overview of the existing analytical, numerical and experimental studies on the web and flange instability of CSW girders. A numerical evaluation of local shear and flexural stability is presented using existing approaches. The influence of different geometrical parameters is summarized and important observations are highlighted for future research in this area. [ABSTRACT FROM AUTHOR]

Prestress concrete composite girders with full‐depth precast bridge deck panels (PC composite girders) have been widely utilized in civil engineering due to their high production quality, reduced construction duration, potential weight reduction, and lower life‐cycle cost. The interface shear behavior in ultra high‐performance concrete (UHPC)–normal concrete (NC) connection interface of full‐depth deck PC composite girder has been extensively studied. This study conducted seven push‐off tests to examine the shear performance of UHPC‐filled joints between precast I‐girders and full‐depth precast concrete slabs. The testing variables included the quantity, and spacing of the Ubars, as well as the type of UHPC‐filled joints (longitudinal trough connector or pocket connector). The experimental results show the quantity and spacing of Ubars have a significant impact on both the interface shear capacity and residual shear resistance. For continuous shear connectors with reserved notches specimens, the ultimate load of the 4Ubar and 6Ubar specimens increased by 93% and 194%, respectively, compared with the 2Ubar specimens. With the increase of the spacing of the Ubar, the ultimate load will decrease. When the spacing between Ubars increases from 100 to 150 mm, the normalized ultimate load decreases by 51 kN. The type of joints also plays a crucial role in determining the ultimate shear‐bearing capacity of the specimens. The Ubars in pocket connector specimens will provide a greater contribution to the ultimate shear bearing capacity than longitudinal trough connector specimens and the ultimate stress of the 4Ubar and 6Ubar pocket connector specimens are greater than that of the longitudinal trough connector specimens by 232% and 323%. The study introduces the concept of pulling angle. In the experiment, the specimen with a large length is less affected by the pulling force. The experimental results in this study can rarely be predicted well by typical equations developed in current design codes and previous studies. Therefore, a more accurate equation was developed to predict the interface shear transfer stress between precast common concrete I‐girder and full‐depth precast concrete slab with UHPC‐filled joints. [ABSTRACT FROM AUTHOR]

Introduction/purpose: The paper analyses and optimizes the welded I-girder of the single-beam bridge crane with a U-profile as the top flange. This solution is to provide a lighter carrying structure, so the main goal is to minimize the weight of the main girder, i.e., the cross-sectional area while fulfiling the requirements defined by national standards and geometric constraints. Methods: The Moth-Flame Optimization (MFO) algorithm was chosen for solving this single-objective multi-criteria optimization task using MATLAB. Also, the results were verified by using the Finite Element Analysis (FEA). Results: The proposed girder shape is justified in examples of real solutions of single-beam bridge cranes and the previous research results. In this case, significant savings in the material and better results are achieved compared to the examples from the previous research. Conclusion: The proposed girder shape, methodology, the optimization algorithm and the achieved savings fully justify this research. Furthermore, this algorithm enables the application of many constraint functions, whereby the optimal values of numerous variables are obtained in a relatively short period. Therefore, it would not be possible to find the solution for that engineering task by applying analytical optimization methods. [ABSTRACT FROM AUTHOR]