Hasil untuk "Bridge engineering"

Tingting Ma, Jun He, Guolin Gao et al.

The complexity of the loading mode and action mechanism is demonstrated in the portal frame anti-uplift structure. The stress evolution process of the portal frame structure during the excavation of the upper foundation pit is revealed through in situ structural stress tests and numerical modeling analysis reflecting the small strain characteristics of stratum. The stress distribution of uplift piles and anti-floating plates is analyzed, with the axial force of piles and the development law of bending moment in plates being specifically examined. It is emphasized that the load of the uplift pile is generated by friction between the pile and soil caused by stratum floating, which is predominantly produced during the excavation of the upper block and the unloading of the surcharge. The pile 11# is observed to be under tension in the middle and compressed at both ends, with the extreme value of tensile stress of these 24 piles being located at 0.15 times the pile length below the top of the middle pile. The main loads of the anti-floating plate are identified as backfilling, foundation buoyancy, and lateral soil pressure. The lower part of the two pile spans is subjected to tension, while the upper part is under compression, with the bending moment extremes being located on the side where the frame is first formed. A significant increase in stiffness is exhibited by the frame structure after its formation, and the influence from the excavation of other blocks is markedly reduced. The most adverse condition is determined to occur during the integral removal of the upper surcharge. The reference value of these research results is confirmed for clarifying the stress mechanism of anti-uplift portal frame structures and optimizing key technical parameters in structural design and construction.

Wenshuai Li, Qiyu Tao, Chao Li et al.

This study examines the in-situ lateral static load behavior of a closed-diaphragm wall foundation, aiming to better understand its load–displacement response, structural behavior, and soil interaction under horizontal loading. An in-situ static load test was conducted with a maximum applied load of 70 MN, revealing that the diaphragm wall initially exhibits a linear load–displacement response, which becomes increasingly nonlinear as the load increases. The horizontal displacement of the lateral walls is nearly identical to the overall displacement of the diaphragm wall, making it a reliable indicator of the wall’s load state, particularly when it is challenging to measure total displacement. The wall behaves as a rigid body with minimal relative displacement between sections, and overturning failure is identified as the primary failure mode. Earth pressure distribution varies around the wall: passive earth pressure is observed at the front edge, while active and passive pressures alternate at the rear edge. These findings provide valuable insights into the design of diaphragm wall foundations, emphasizing the importance of lateral displacements.

Yan-Kun Zhang, Pei Yuan, Bo Geng et al.

As a potential fire scenario for bridge structures, the safety impact of an FRP anti-collision floating pontoon fire on bridge structures cannot be ignored. Taking the FRP anti-collision floating pontoon fire that occurred in a continuous rigid-frame bridge as the engineering background, the damage condition of the actual bridge fire scene was first investigated. In addition, FDS 5.3 software was used to simulate the FRP anti-collision floating pontoon fire scenario. Furthermore, the thermal–structural coupling method was used to investigate the thermodynamic response of double-armed thin-walled piers under fire. The results show that the FRP anti-collision floating pontoon fire causes localized concrete carbonization and spalling on the surface of the P2 pier, and the FRP anti-collision floating pontoons are largely destroyed. The fire has the greatest impact on the P2-1 pier, with the highest temperature of 667 °C on the windward side and the highest temperature of 326 °C on the leeward side. The temperature impact range is 6 m above the bearing platform, and the maximum damage depth of pier body concrete is 84.58 mm. The deformation and stress of the P2 pier under fire do not show significant changes and do not exceed the allowable limits for structural deformation and material stress. Therefore, the impact of this fire accident on the structural safety of the continuous rigid-frame bridge is minor. This study’s results provide reliable guidance for the fire safety assessment and post-fire structural repair of the continuous rigid-frame bridge.

Rong Wang, Xinyang Zhou, Yi Liu et al.

To ensure the safety and durability of concrete structures, timely detection and classification of concrete cracks using a low-cost and high-efficiency method is necessary. In this study, a concrete surface crack damage detection method based on the ResNet-18 residual network was developed. This method was implemented by training a model with images to extract the cracks, where the image processing algorithms and deep learning were combined. The results show that the computational accuracy can meet the requirements by utilizing the established image dataset and appropriate model hyperparameters. The trained model had high recognition accuracy when the 256 × 256 resolution images were adopted, and the worst accuracy of crack recognition in the test set was over 90%. The average accuracy in the test set was 91.3% when considering environmental interference generated by processing the images with a brightness adjustment, salt-and-pepper noise, and localized interference. Then, it was demonstrated that the present model possesses good robustness for crack identification in different environments. The average recognition accuracy when dealing with images of a real bridge, which are outside the training dataset, was 99.7%. The residual network model developed in this study has the advantages of low cost, high efficiency, and practicality compared to traditional detection methods. Compared to the existing deep learning methods, the model created in this study requires less computational resources and storage space, and shows a faster training speed and higher accuracy.

Hicham Lamouri, Mouna EL Mkhalet, Nouzha Lamdouar

Abstract The approximation of complex engineering problems and mathematical regressions serves as the authentic inspiration behind the artificial intelligence metamodeling methods. Among these methods, polynomial chaos expansion, along with artificial neural networks, has emerged at the forefront and become the most practical technique. Previous studies have highlighted their robust capabilities in solving complex problems and their wide utilization across numerous applications, particularly in structural analysis, optimization design problems, and predictive models of uncertainty outcomes. The aim of this article is to present a methodology that introduces their implementation of for structural engineering, primarily focusing on reinforced concrete bridges. The proposed approach consists of demonstrating the applicability of the polynomial chaos to evaluate the dynamic behavior of two-span reinforced concrete bridges through a predictive model of natural vibration properties for eigenvalues modal analysis. Subsequently, response spectral method is conducted according to the Moroccan guide for bridge seismic design and the prescription of the EUROCODE 8 within the context of reliability assessment using Monte Carlo simulation. The efficacy of the proposed approach is illustrated by a comparison between the predicted vibration properties and the resulting values obtained through finite element modal analysis and artificial neural networks. The polynomial chaos process is based on a collected dataset of multiple reinforced concrete bridges sourced from technical studies offices and the Regional Administration of the East, affiliated with the Moroccan Ministry of Equipment and Water. Finally, this work contributes to the field by enhancing predictive modeling and reliability evaluation for bridge engineering using artificial intelligence metamodels.

MA Zhicong, MEI Bo, SU Li et al.

Aiming at the corrosion problem of steel bars in concrete in subtropical marine environment, the full immersion corrosion experiments of reinforced concrete specimens with different strength grades and rust inhibitor contents were carried out by simulating the subtropical marine environment.The macroscopic indexes such as chloride ion content were tested by electrochemical non-destructive testing, and the experimental results were verified by microscopic detection methods.The corrosion degradation patterns of reinforced concrete was analyzed.The results show that the improvement of concrete strength grade and the increase of rust inhibitor content can significantly improve the corrosion resistance of reinforced concrete.Among them, the corrosion resistance of C30 concrete is the worst.At 120 d, the corrosion current density is 0.118 μA/cm2, the polarization resistance is 220 kΩ cm2, the concrete resistance is 87.3 kΩ cm2, and the transfer resistance of the steel-concrete interface area is 77.3 kΩ cm2, reaching the passivation state.When the concrete strength grade is increased to C50, the corrosion current density is reduced by 58.47%, the polarization resistance is increased by 3.82 times, and the concrete resistance is increased by 44.56%;when the amount of rust inhibitors is 6 kg/m3, the corrosion current density is reduced by 47.45%, the polarization resistance is increased by 2.81 times, and the transfer resistance at the reinforcement-concrete interface is increased by 72.43%.

Valentina Rueda-Castro, Jose Daniel Azofeifa, Julian Chacon et al.

IntroductionIn transitioning from Industry 4.0 to the forthcoming Industry 5.0, this research explores the fusion of the humanistic view and technological developments to redefine Continuing Engineering Education (CEE). Industry 5.0 introduces concepts like biomanufacturing and human-centricity, embodying the integration of sustainability and resiliency principles in CEE, thereby shaping the upskilling and reskilling initiatives for the future workforce. The interaction of sophisticated concepts such as Human-Machine Interface and Brain-Computer Interface (BCI) forms a conceptual bridge toward the approaching Fifth Industrial Revolution, allowing one to understand human beings and the impact of their biological development across diverse and changing workplace settings.MethodsOur research is based on recent studies into Knowledge, Skills, and Abilities taxonomies, linking these elements with dynamic labor market profiles. This work intends to integrate a biometric perspective to conceptualize and describe how cognitive abilities could be represented by linking a Neuropsychological test and a biometric assessment. We administered the brief Neuropsychological Battery in Spanish (Neuropsi Breve). At the same time, 15 engineering students used the Emotiv insight device that allowed the EEG recollection to measure performance metrics such as attention, stress, engagement, and excitement.ResultsThe findings of this research illustrate a methodology that allowed the first approach to the cognitive abilities of engineering students to be from neurobiological and behavioral perspectives. Additionally, two profiles were extracted from the results. The first illustrates the Neuropsi test areas, its most common mistakes, and its performance ratings regarding the students' sample. The second profile shows the interaction between the EEG and Neuropsi test, showing engineering students' cognitive and emotional states based on biometric levels.DiscussionsThe study demonstrates the potential of integrating neurobiological assessment into engineering education, highlighting a significant advancement in addressing the skills requirements of Industry 5.0. The results suggest that obtaining a comprehensive understanding of students' cognitive abilities is possible, and educational interventions can be adapted by combining neuropsychological approaches with EEG data collection. In the future, it is essential to refine these evaluation methods further and explore their applicability in different engineering disciplines. Additionally, it is necessary to investigate the long-term impact of these methods on workforce preparation and performance.

Jinjian Li, Bing Hu, Liyang Zhao et al.

The development of high-efficiency multi-wire submerged arc welding technology in bridge engineering has been limited due to the high mechanical performance standards required. In this paper, weld metal was obtained by welding at three different high heat inputs with the laboratory-developed high-efficiency submerged arc welding wire for bridges. The effect of changing different high heat inputs on the microstructure and impact toughness of high efficiency submerged arc weld metal was systematically investigated by cutting and Charpy V-notch impact tests at −40 °C, using optical microscopy, scanning electron microscopy, energy-dispersive electron spectroscopy, electron backscatter diffraction, and transmission electron microscopy to characterize and analyze. With the increase in heat input from 50 kJ/cm to 100 kJ/cm, the impact absorption energy decreased significantly from 130 J to 38 J. The number of inclusions in the weld metal significantly decreased and the size increased, which led to a significant decrease in the number of inclusions that effectively promote acicular ferrite nucleation, further leading to a decrease in the proportion of acicular ferrite in the weld metal. At the same time, the microstructure of the weld metal was significantly coarsened, the percentage of high-angle grain boundaries was decreased, and the size of martensite/austenite constituents was significantly increased monotonically. The crack initiation energy was reduced by the coarsened martensite/austenite constituents and inclusions, which produced larger local stress concentrations, and the crack propagation was easier due to the coarsened microstructure and lower critical stress for crack instability propagation. The martensite/austenite constituents and inclusions in large sizes worked together to cause premature cleavage fracture of the impact specimen, which significantly deteriorated the impact toughness. The heat input should not exceed 75 kJ/cm for high-efficiency submerged arc welding wires for bridges.

Liu Lihong, Jiang Peng, Wen Yongshuai

[Objective] The influence of water-related structures on the flood routing process before and after structure construction was analyzed to provide scientific supports for the real and efficient calculation of bridge engineering in flood storage and detention areas, and for the effective development of flood control in flood storage areas. [Methods] The Mengwa flood storage area in Fuyang City, Anhui Province was selected as the study area. Based on the latest data of regional topography, hydrological data, and bridge engineering design, the unstructured hydrodynamic model of MIKE 21 was used to simulate the flood evolution process of the Mengwa flood storage area in real time. The influence of bridge construction on flood evolution time, velocity distribution, and water level change in the flood storage and detention area was analyzed. [Results] After the construction of the bridge project, the flood-splitting time near the bridge position was 45 s behind the maximum lag before the construction of the project; the flow rate distribution range of the mainstream area was 0.4 to 0.6 m/s; the local velocity change rate was 7.409%; the maximum elevation value of the water level near the bridge was 0.006 m; and the maximum change rate of the water level was -0.22‰. [Conclusion] Bridge construction delayed the flooding time in the flood storage area, raised the water level near the pier, and changed the distribution of the flow rate near the project. However, the overall impact on the flood storage area was small, and basically did not affect the normal operation of the flood storage area.

Bruno Briseghella, Vittoria Borghese, Carlotta Pia Contiguglia et al.

Abstract One of the biggest issues in civil engineering is the poor performance of concrete repairs. In fact, in Europe only 50% of concrete structures restorations are estimated to be successful, even though rehabilitation costs account for about half of the yearly construction budgets. This research aims at investigating a potential green approach to the sustainability of rehabilitation solutions for infrastructures. Following a simplified analysis of C02 emissions, intervention costs, social aspects, structural performances and other variables considered relevant to the scope, possible rehabilitation techniques are compared and ranked. The following four different options have therefore been designed to be applied to an actual column of the Brabau Bridge in Sardinia (Italy): i. complete removal and replacement of the column, ii. replacement of the damaged longitudinal rebars by machined bars and ultra-high performance fibre-reinforced concrete (UHPFRC) strengthening, iii. longitudinal and transverse fiber reinforced polymers (FRP) wrapping, iv. concrete jacketing. A methodological and procedural strategy is established through multi-criteria analysis that will allow future developments to assess the whole Life Cycle Assessment of the maintenance work.

Sina Salamatpoor, Yaser Jafarian, Alborz Hajiannia

The shortcoming of loose sandy soils in terms of shear strength besides placement of a huge number of structures on them drive the critical requirement for exploring the shallow foundations treatment, their positioning and shapes. In this regard, stabilization of loose sandy soils through fabricating cement and an appropriate additive is one of a promising solution. Hence, in this study, a series of unconfined compressive strength tests have been conducted to find out the mechanical properties of zeolite cemented sand composites. Afterwards, 1g small scale tests have been performed to measure the behavior of shallow foundations placed on the stabilized ground. The main aims of this study are enhancing the bearing capacity and conversely decreasing the settlement of foundations attributed to the chemical reactions between sand, cement and zeolite particles. The results demonstrate that placing a zeolite pad with B/3 thickness underneath the shallow foundation, which contain 3% and 7% cement content, increases their bearing capacity in a range between 11% and 23% respectively compared to those of without a zeolite pad. This is followed by respectively 44% and 67% enhancement in the bearing capacity through doubling the thickness of the zeolite pad. Considering the cement content as a comparing factor between the samples, increasing in the resistant coefficient is in a range between 9% to 23%, while it is constantly 6% for the decreasing coefficient. In summary, this stabilization approach improves the behavior of shallow footing on loose soils.

Cuizhen Xue, Hongxia Qiao, Hui Cao et al.

The pile-up of massive construction waste causes serious challenges to environment and engineering practice. In order to promote the reuse rate of construction waste bricks, the effects of the content and fineness of construction waste brick powder and of brick powder-silica flour mixture on the strengths of cement mortar were experimentally investigated. Based on the test results, the significance of the particle characteristics of brick powder on mortar strength was analyzed by grey entropy method. The experimental results show that the early strength of cement mortar decreases due to the addition of brick powder; the reduction is, however, not significant when the content of brick powder is less than 10%; the 28 d strength of cement mortar increases with a proper content of brick powder. The grey entropy analysis indicates that the particle characteristics have strong influence on the activity of brick powder and mortar strength; the strength is significantly dependent on specific surface area and the fraction of particles smaller than 20 μm. Fine brick powder and silica flour can improve the macroscopic strengths of cement mortar by affecting the type and quantity of hydration products and the structure of interfacial transition zone between cement paste and sand.

Julia Rulent, Julia Rulent, Francisco M. Calafat et al.

Accurately resolving coastal Total Water Levels (TWL) is crucial for socio-economic and environmental reasons. Recent efforts in satellite altimetry and numerical modeling have improved accuracy over near-shore areas. In this study we used data from tide gauges (TGs), SAR-mode altimetry from two satellites [Sentinel-3A (S3) and CryoSat-2 (C2)], and a state-of-the-art high-resolution regional coupled environmental prediction model (Amm15) to undertake an inter-comparison between the observations and the model. The aim is to quantify our capability to measure TWL around the United Kingdom coast, and to quantify the capacity of the model to represent coastal TWL. Results show good agreement between the satellite and TG data [the mean correlation (R) over seventeen TGs between June 2016 and September 2017 is 0.85 for S3 and 0.80 for C2]. The satellite-model comparison shows that the variability is well captured (R = 0.98 for both satellite), however, there is an offset (−0.23 m for S3, −0.15 m for C2) between the satellite and model data, that is near-constant across the domain. This offset is partly attributed to the difference in the reference level used by the satellites and the model, and residual differences linked to the temporal resolution of the model. The best agreement between model and satellite is seen away from the coast, further than 3–4 km offshore. However, even within the coastal band, R remains high, ∼0.95 (S3) and ∼0.96 (C2). In conclusion, models are still essential to represent TWL in coastal regions where there is no cover from in-situ observations, but satellite altimeters can now provide valuable observations that are reliable much closer to the coast than before.

Shuangjie Zheng, Chen Zhao, Yangqing Liu

In steel and concrete composite structures, it is unfavourable to install many headed studs or perfobond ribs with narrow spacings at the joints. To solve this problem, a new type of a mixed shear connector was developed by combining a headed stud and perfobond rib at the same steel beam flange. In this paper, totally nine push-out tests were conducted. The main purpose was to compare the failure mode and the load-slip behavior of the headed stud, perfobond rib, and mixed shear connector. Furthermore, 19 nonlinear finite element simulations were performed. The effects of connector dimension and material properties on the structural behaviors of mixed shear connectors were studied. Based on the experimental and parametric study, an analytical equation was finally proposed to evaluate the shear capacity of perfobond rib with a headed stud mixed shear connector.

Jiarui Zhang, Jianwei Tu, Zhao Li et al.

A new piezoelectric composite, macro fiber composite (MFC) is recombined with piezoceramic fibers, an epoxy resin basal body, and an interdigitated electrode. It has been widely applied in vibration reduction and deformation control of thin-walled structures, due to its great deformability and flexibility. Research on its actuation performance is mostly concentrated on the MFC actuating force calculation based on classical plate theory (CPT), and the overall modeling of MFC and its structure. However, they have some deficiencies in the tedious calculating process and neglect of shear deformation, respectively. To obtain a precise MFC actuating force, the sinusoidal shear deformation theory (SSDT) is adopted to deduce the MFC actuating force formula, and global−local displacement distribution functions are introduced to help the MFC laminated plate structure satisfy the deformation compatibility and stress balance. For instance, in the end displacement calculation of the MFC laminated beam structure. The experimental result of the MFC laminated beam is compared with those of the MFC actuating force based on SSDT and on CPT, which indicates that the MFC actuating force formula based on SSDT can reach higher computational accuracy.

Mohammad Ali Hadianfard, Mahboobe Namjoo

After failure of a column in structure by an abnormal loading, undesirable performance and damage of connections of the beams connected to the top of this column, can lead to the local failure of floor and in turn result in progressive collapse in the structure. Accordingly, the best method for rehabilitation of the structure against this incident is the strengthening of the connections. The strength and flexibility of the connections during the large rotations result in spreading the axial forces in beams and forming the catenary action. This action can greatly prevent structural failure due to the column removal. In this paper, the performance of prevalent bolted and welded top and seat angle steel connections is evaluated numerically. All parts of the connections are modeled in finite element software. The modeled structure is analyzed nonlinearly under the vertical displacement in the location of removed column, and its results have been verified with experimental results. In addition, the behavior, failure modes, how the catenary action develops and the effects of different parameters on connection behavior are investigated. The results indicated that bolted connections have better performance than welded connections.Also, in welded connections, increasing the thickness of the angles and increasing the length of the connected angle leg to column, improve the catenary action and the resistance of the connections against progressive collapse. But adding the stiffener plate in the middle of the seat angle does not increase the connection capacity in all cases.

Hui Wang, Eva Binder, Herbert Mang et al.

This paper contains an assessment of the added value of multiscale material models for concrete in the context of macroscopic structural analysis of (steel-reinforced) concrete structures. Two examples are discussed. They are inspired by the possibility of car accidents inside the immersed tunnel of the Hong Kong-Zhuhai-Macao Bridge (HZMB). The first example deals with vehicles crashing into the tunnel wall. The high-dynamic strengthening effect of concrete is studied based on an engineering mechanics model. The structural nature of the dynamic strength increase factor (DIF) is demonstrated by means of high-dynamic strength values measured on mortar cylinders of different size. Furthermore, the evolution of the DIF as a function of hardening of concrete at material ages beyond 28 days is studied. A validated multiscale model for concrete renders a customized analysis for the specific concrete used for the aforementioned tunnel possible. It is found that the DIF decreases with progressive hardening of concrete at material ages beyond 28 days. The second example is inspired by tunnel fires as may happen after car accidents. The study refers to thermal stresses in steel-reinforced concrete beams subjected to sudden heating. The thermal expansion coefficient of the concrete of the tunnel is quantified by means of a multiscale model. It is used as input for linear thermo-mechanical Finite-Element simulations of steel-reinforced concrete beams. The essential macroscopic simulation results are temperature distributions and associated stress fields. They are employed for top-down quantification of microscopic stress states inside the cement paste and the aggregates. This allows for quantifying two sources of microstructural stress fluctuations: (i) the macro-to-micro stress concentration and (ii) the mismatch of microscopic thermal expansion coefficients. In both examples, the multiscale models for concrete have increased the informative content of the structural simulations. Keywords: Concrete linings, High-dynamic strength, Thermal stresses

Weiwei Lin, Teruhiko Yoda

Kazys Petkevičius, Daiva Žilionienė, Viktoras Vorobjovas

The state of hot mix asphalt pavement and its structure, predetermined by the distress level, largely depends on the functional conditions. The factors predetermining the functional conditions and service life of hot mix asphalt pavement and its structure are discussed in the present article: traffic loads, local climate and weather conditions, local soils (their properties), and other local factors (soil water level and moisturizing conditions, etc.). It is shown that the state of the road pavement and its structure expressed in the distress level, the roughness of hot mix asphalt pavement strength, expressed by strength coefficient Kst, largely depends on the componential composition of the upper layer of hot mix asphalt pavement and its physical and mechanical properties. The article contains recommendations for maintaining the required state of hot mix asphalt pavement and its structure (when D ≤ 8%) and for renewal of the service life of the pavement and its structure.