Search Results (1,344)

Vehicle load is one of the primary factors influencing fatigue damage in reinforced concrete beam bridges, and diseases of bearings will accelerate the fatigue damage of beam bridges, but most of the current studies only consider the influence of vehicle load on the fatigue damage of beam bridges. In order to evaluate the fatigue damage of T-beam bridges more comprehensively, a numerical analysis method for the entire fatigue damage process of T-beam bridges is proposed, which considers the impact of bearing diseases and vehicle loads. The research results indicate the following: (1) During the fatigue calculation process of the T-beam, the maximum tensile fatigue damage value grows rapidly in the early stages. The effects of different bearing diseases and severities on the T-beam are generally similar. In the mid-stage, the growth of the maximum tensile fatigue damage value slows down, and the deeper the bearing disease, the greater the impact on the T-beam. In the later stage, the damage value grows rapidly until failure. (2) The displacement of bearings leads to stress concentration in the beam and the steel plates of bearings. The larger the slippage amplitude, the greater the stress value, which leads to a shortened lifespan of the concrete beam. (3) Bearing maintenance should focus on the damage of the beam. If displacement of bearings occurs, measures should be taken as early as possible (preferably within the mid-stage, 10–65 years); otherwise, it will result in a significant decrease in the beam’s life. Full article

PC steel material inside pre-stressed concrete bridges is prone to corrosion due to the effect of salt, which leads to cross-sectional losses and fractures if proper maintenance is not carried out, affecting the girders’ structural performance. In Japan, pre-tensioned girders incorporating small-diameter PC steel material with a span length of 13 m or less were used until the early 1980s. Thus, it is essential to understand the fracture conditions of PC steel material and the factors affecting section loss due to corrosion, in order to properly assess the residual strength of salt-affected pre-tensioned girders. Hence, the current research clarifies the accuracy of techniques used for detecting deterioration in a pre-tensioned PC girder that had been out of service for about 40 years, caused by exposure to the severely saline environment of the Okinawa coast. Visual and hammer-tapping investigation of the actual bridge in addition to fracture investigation of the PC steel material using the triaxial magnetic method and destructive investigation of the concrete cover on the bottom of the girder were carried out and correlated. The final results confirmed that the triaxial magnetic method could detect PC steel material fractures accurately, and valuable information was obtained regarding fracture-detection technology for application in PC girders via non-destructive testing. Full article

Reinforced Concrete (RC) barriers are used for different purposes in the highway inventory. An important purpose is the use of concrete barriers to act as railing that protects bridge piers against vehicular collision force (VCF). Therefore, these barriers are designed to absorb the collision energy and/or redirect the vehicle away from the parts being protected. Accurate estimation of the capacity of RC barriers during crash events is an important consideration in their design and placement. The American Association of State Highway and Transportation Officials (AASHTO) considers yield line analysis (YLA) with the V-shape failure pattern to predict the barrier capacity. AASHTO’s analysis method involves some assumptions that are intended to simplify the analysis process. Some of these assumptions have been shown to underestimate the actual barrier capacity and might disqualify many existing RC barriers from acting as intervening structures due to structural inadequacy. Many researchers have proposed alternative failure patterns and methodologies in an attempt to better predict the capacity of RC barriers. This research shows that AASHTO’s YLA, with the current V-shape failure pattern, can be improved and still predict the barrier capacity when some of the simplifying assumptions are eliminated. Also, the research presents an alternative innovative truss analogy model to predict the capacity of RC barriers. The results of the improved YLA and the proposed truss model are validated by finite element analysis (FEA) using Abaqus. The results of this research will help structural engineers in the highway industry to initially design new barriers for the intended capacity as well as estimate the capacity of existing ones. Full article

Despite significant advancements in bridge façade defect classification, real-world automated inspections continue to face substantial challenges, including faint defect visibility, low lighting conditions, overexposure, noise interference, motion blur, and occlusions. These factors, stemming from variable environmental conditions and unstable imaging angles, severely degrade model performance. To address this issue, we introduce the Hard Defect Classification Dataset (HDCD), which systematically incorporates these six challenging conditions. Benchmarking state-of-the-art (SOTA) methods on the HDCD reveals a substantial performance drop on hard samples, highlighting the limitations of existing approaches in capturing class-specific features under adverse conditions. To enhance robustness, we propose the Prototypical Prompt Learning Framework (PPLF), inspired by prompt learning. PPLF utilizes category prototype vectors as dynamic prompts to interact with query features, guiding the model to focus on defect regions while suppressing background noise. A hierarchical feature fusion mechanism further integrates low-level texture details with high-level semantic patterns, improving defect localization and classification. Extensive experiments on ResNet-50, EfficientNetV2-L, and ViT demonstrate that PPLF consistently outperforms SOTA methods, especially achieving a 7% improvement on ResNet-50, showcasing its effectiveness in real-world civil engineering applications where robustness to challenging conditions is critical. Full article

Regular crack detection is essential for extending the service life of bridges. However, the image data collected during bridge crack inspections are complex to convert into physical information and construct intuitive and comprehensive Three-Dimensional (3D) models incorporating crack information. An intelligent crack detection method for bridge surface damage based on Unmanned Aerial Vehicles (UAVs) is proposed for these challenges, incorporating a three-stage detection, quantification, and visualization process. This method enables automatic crack detection, quantification, and localization in a 3D model, generating a bridge model that includes crack details and distribution. The key contributions of this method are as follows: (1) The DCN-BiFPN-EMA-YOLO (DBE-YOLO) crack detection network is introduced, which improves the model’s ability to extract crack features from complex backgrounds and enhances its multi-scale detection capability for accurate detection; (2) a more comprehensive crack quantification method is proposed, integrating the crack automation detection system for accurate crack quantification and efficient processing; (3) crack information is mapped onto the 3D model by computing the camera pose for each image in the 3D model for intuitive crack visualization. Experimental results from tests on a concrete beam and an urban bridge demonstrate that the proposed method accurately identifies and quantifies crack images captured by UAVs. The DBE-YOLO network achieves an accuracy of 96.79% and an F1 score of 88.51%, improving accuracy by 3.19% and the F1 score by 3.8% compared to the original model. The quantification accuracy is within 10% of the error margin of traditional manual inspection. A 3D bridge model was also constructed and integrated with crack information. Full article

In many construction applications, including bridge pedestals, concrete corbels, and concrete anchors, the concrete’s local compressive strength attribute (bearing) is crucial. One of the benefits from concrete’s bearing is its role in mitigation construction failure risk and increase the safety of the buildings. The local compression characteristics of fully hardened concrete were the primary focus of earlier study, with less attention paid to early age concrete (less than 28 days). In order to evaluate the bearing qualities of early age concrete—here defined as the first month—the current experimental program is being carried out. While the bearing plate’s area (Ab), which was placed in the middle of each block’s top surface, differed in dimension (100 × 100 mm, 80 × 80 mm, 60 × 60 mm, and 40 × 40 mm), the concrete pedestals’ size remained constant at 250 × 250 × 200 mm. Tests were conducted on sixteen concrete supports. Four equal groups of samples were created, and each group underwent testing at a different age (T = 3, 7, 15, and 28 days). In each group, unloaded-to-loaded area is varied (A₁/A_b = 6.25, 9.76, 17.36, and 39). The failure, bearing stress–slip curve, ultimate bearing strength and ultimate associated deformation of the tested concrete supports were studied. The results showed that the compressive and tension strengths increased by 178% and 244% when the concrete age reached 28 days compared to 3 days-concrete. As A₁/A_b or/and concrete age increased, the bearing characteristics improved more. The ultimate bearing strength increased by 51%, 56.5%, and 69.5% at $\sqrt{{\displaystyle \frac{A_1}{A_b}}}$ = 6.25 when the samples’ concrete age increased from 3 to 7, 15, and 28 days. The main contribution of this study is a novel formula to forecast the concrete’s bearing strength while accounting for the impact of the concrete’s age and the ratio $\sqrt{{\displaystyle \frac{A_1}{A_b}}}$. Full article

This review article provides an in-depth exploration of the recent advancements in the seismic analysis and design of steel–concrete composite structures, as reflected in the literature from the last ten years. It investigates key factors, such as material behavior, connection detailing, analytical modeling techniques, and design methodologies. The article highlights the synergistic benefits derived from the combination of steel and concrete components to improve seismic performance. Various composite systems, including composite beams, beam-columns, frames, shear walls, foundations, and beam–column joints, are analyzed through experimental studies to assess their dynamic response characteristics under extreme earthquake conditions. The article evaluates advanced numerical modeling methods, including finite element analysis and fiber-based models, for their capability to predict the nonlinear behavior of composite buildings and bridges. A comparative analysis of modern seismic isolation and energy dissipation techniques is also included. Furthermore, the optimization of composite structures in seismically active regions is discussed. The article concludes by identifying areas where additional research is necessary to enhance the seismic resilience of steel–concrete composite structures. Full article

Due to moisture migration effects, thermal and moisture bridges tend to form at building joints, thereby increasing the thermal conductivity coefficient of construction materials. To examine the influence of moisture transfer on the thermal performance of ‘one-line’ vertical joint walls, this study establishes a thermal–humidity coupling numerical model at the vertical joint of sandwich insulation composite walls. This model is employed to analyze the effects of various joint filling materials (aerated blocks, glass wool, concrete), insulation layer thicknesses, and environmental conditions on the thermal transfer properties of the wall joint. The results indicate that when filled with aerated blocks, the joint is most significantly affected by moisture transfer, exhibiting a heat flow loss rate of 8.08%. In high-temperature environments, the thermal transfer performance at the connection of the composite wall is particularly susceptible to humidity, with heat flow loss rates ranging from 6.17% to 8.74%. Furthermore, an increase in the thickness of the insulation layer leads to a reduction in the “heterogeneity” of the sandwich insulation wall, which reduces the wall’s effects to moisture transfer; however, this is accompanied by a rise in the heat loss rate at the connection. After accounting for the effects of hygrothermal bridging, the mean heat transfer corrected coefficient of the wall in areas with hot summers and cold winters ranges from 1.10 to 1.18 during the summer and from 1.12 to 1.16 during the winter. This finding holds significant relevance for aiding researchers in predicting thermal transfer analysis in scenarios involving wall moisture transfer. Full article

The main objective of this research is to evaluate the optimal design of the tendon profile layout and to examine the effect of the tendon profile layout on the flexural strength of unbonded, post-tensioned prestressed concrete bridge I-girders. In this study, the experimental investigation involved casting and testing ten unbonded, post-tensioned bridge girders under four-point loads. The main variable studied was the tendon profile layout. The experimental results showed that the flexural behavior of the tested specimens is divided into three stages, including the elastic stage, elastic–plastic stage, and plastic stage, and all specimens exhibited flexural failure. It can be concluded that for each tendon profile layout (trapezoidal, parabolic, harped), the tendon profile with eccentricity at the end of the beam (e_e) = 0 had the maximum ultimate load capacity. It also can be concluded that specimen GF-2 HA (harped tendon profile with e_e = 0 mm) had the maximum ultimate load capacity among all of the specimens. These enhancements in specimen stiffness, ultimate load capacities, and deflections are due to an increase in resisting capacity, a reduction in stresses, especially at the supports, a decrease in deflection, and an increase in the resisting bending moment, which lead to a reduction in the production cost of the girder. Full article

The construction of highway bridges using continuous precast prestressed concrete girders provides an economical solution by minimizing formwork requirements and accelerating construction. Different ways can be used to integrate bridge continuity and enable the development of negative bending moments at piers. Continuous bridge connections enhance structural integrity by reducing deflections and distributing loads more efficiently. Research has led to the development of various continuity details, categorized into partial and full integration, to improve performance under diverse loading conditions. This review summarizes studies on both partial and fully integrated continuous bridges, highlighting improvements in connection resilience and the incorporation of advanced construction technologies. While extended deck reinforcement presents an economical solution for partial continuity, it has limitations, especially in longer spans. However, full integration provides additional benefits, such as further reduced deflections and bending moments, contributing to improved overall structural performance. Positive-moment connections using bent bars have shown enhanced performance in achieving continuity, though skewed bridge configurations may reduce the effectiveness of continuity. Ultra-High-Performance Concrete (UHPC) has been identified as a superior material for joint connections, providing greater load capacity, durability, and seismic resistance. Additionally, mechanical splices, such as threaded rod systems, have proven effective in achieving continuity across various load types. The seismic performance of precast prestressed concrete girders relies on robust joint connections, particularly at column–foundation and column–cap points, where reinforcements such as steel plates, fiber-reinforced shells, and unbonded post-tensioning are important for shear and compression transfer. Full article

Cracks in reinforced concrete structures compromise strength and durability, particularly in high-performance centrifugal concrete (HPC) piles, where degradation can become irreversible. Despite their high density and low permeability, HPC piles remain vulnerable to cracking, sulfate attack, and chloride penetration, necessitating innovative durability solutions. While self-healing concrete has been widely studied, its application in HPC piles remains unexplored, representing a critical research gap. This study investigates the synergistic use of Bacillus sphaericus bacteria and flax fibers to enhance crack healing, permeability reduction, and mechanical performance in HPC piles. In this research, HPC specimens were fabricated using a specialized centrifugal device and casting process. During the mixing phase, bacteria and flax fibers were incorporated into the concrete. The fresh mix was then spun to form the final specimens. To evaluate bacterial self-healing performance of specimens, controlled random cracks were induced using a compression testing machine. Thereafter, a series of compressive strength tests, 30 min water absorption tests (BS 1881), scanning electron microscopy (SEM) combined with energy dispersive X-ray spectroscopy (EDS), and EDS mapping (MAP) were conducted to evaluate self-healing efficiency. Results demonstrated that bacterial activation upon cracking led to calcium carbonate precipitation, effectively sealing cracks, reducing permeability, and enhancing compressive strength. Optimizing bacterial and fiber content further influenced water absorption and mechanical properties in both cubic and centrifugally cast specimens. This study bridges a critical gap by introducing biomaterial-based self-healing in HPC piles, offering a sustainable, cost-effective, and long-term strategy for enhancing the durability of deep foundation systems in aggressive environments. Full article

Numerous catastrophic events, including fire, vehicle collisions, and air blasts, have highlighted the significance of examining bridge performance under multi-hazard scenarios. While these hazards cause extensive damage, the loss of life, and drastically impact economies, limited attention has been devoted to study the behavior of bridge structural elements under such extreme demand combinations. Hence, comprehensive research to understand the resiliency of bridges and their response to combinations of fire, vehicular impact, and air blast is warranted so that effective retrofitting techniques can be developed and design recommendations be made. To address this research gap, present investigations utilized previously validated finite element (FE) models in LS-DYNA to study the structural behavior of two-, three-, and four-column piers under post-fire medium truck collision and subsequent air blast. The response of multi-column piers was quantified and evaluated based on damage propagation, failure patterns, and permanent deformation sets. The effectiveness of selected retrofitting techniques that employed carbon-fiber-reinforced polymers (CFRPs) to mitigate damage was investigated. Study findings enhance current understanding, provide valuable insights, and can ultimately be used to ensure safety and improve the structural integrity of bridge piers under coupled vehicle collision and air blast following fire exposure. Full article

To address the challenge of repairing the damage to concrete box girder bridge piers on mountainous highways caused by falling rocks, this paper proposes an active underpinning technique that integrates a “井”-shaped cap system, graded preloading of the foundation, and synchronized beam body correction. The technique utilizes lateral beam preloading (to eliminate the inelastic deformation of the new pile foundation) and longitudinal beam connections (to form overall stiffness). The method involves building temporary and permanent support systems in stages. Through the two-stage temporary support system transition, the removal and in situ reconstruction of the old piers, a smooth transition from the pier–beam consolidation system to the basin-type bearing system is achieved while simultaneously performing precise correction of beam torsion. The structural safety during the construction process was verified through finite element simulations and dynamic monitoring. Monitoring results show that the beam torsion recovery effect is significant (maximum lift of 5.2 mm/settlement of 7.9 mm), and the pier strain (−54.5~−51.3 με) remains within a controllable range. Before the bridge was opened to traffic, vehicle load and impact load tests were conducted. The actual measured strength and vertical stiffness of the main beam structure meet the design requirements, with relative residual deformation less than 20%, indicating that the structure is in good, elastic working condition. The vehicle running and braking dynamic coefficients (μ = 0.058~0.171 and 0.103~0.163) are both lower than the theoretical value of 0.305. The study shows that this technique enables the rapid and safe repair of bridge piers and provides important references for similar engineering projects. Full article

The increasing incidence of urban fires poses significant threats to structural integrity, underscoring the urgent need for concrete materials with enhanced mechanical properties post-fire. Incorporating recycled waste steel fibers (WSF) from industrial byproducts into concrete not only bolsters its crack resistance but also advances circular economy principles by transforming industrial waste into valuable resources. Although a large amount of research has focused on native steel fiber-reinforced concrete, there is still a lack of systematic exploration on the optimal dosage and effectiveness of waste steel fibers in slowing down the strength degradation of concrete after high-temperature action. In this study, two grades of concrete (C40 and C60) containing 0%, 1%, and 2% WSF by volume were subjected to heating cycles ranging from 200 °C to 800 °C. Post-cooling evaluations encompassed mass loss quantification, cube compressive strength testing (using 100 mm³ specimens), and splitting tensile tests conducted at a loading rate of 0.1 MPa/s. Results indicated that mass loss escalated to 11% at 800 °C, with C60 experiencing a 12% higher loss compared to C40. Compressive strength decreased by 15% for every 200 °C increment; however, the inclusion of 1% WSF significantly minimized this degradation, preserving 44.5% (for C40) and 37.8% (for C60) of the original strength at 800 °C. Notably, the splitting tensile strength of 1% WSF-reinforced C60 concrete exceeded that of plain concrete by 39.4% after exposure to 800 °C, demonstrating its superior crack-bridging capabilities. Full article

This article presents the results of a study conducted to obtain the fragility curves of an existing reinforced concrete highway bridge in Kocaeli, Turkey, to investigate the collapse potential. Bridges are key components of transportation systems, providing convenient and efficient access to different locations. However, these structures are susceptible to forces that can cause significant damage in the event of seismic activity. Thus, the fundamental target of designing earthquake-resistant bridges is to ensure that they can remain functional at an acceptable level during seismic activity. At least, they are expected to survive strong earthquakes without collapse. Turkey is a country located on active fault lines and has experienced devastating earthquakes in the past. This high earthquake risk requires the design and construction of bridges that are a critical part of the transportation infrastructure having adequate safety levels so that the collapse risk can be minimized. Therefore, damage estimation of bridges is an important part of earthquake preparedness and the response plans that will be followed immediately after earthquakes. In this study, the fragility curves of an existing reinforced concrete highway were obtained to investigate the collapse potential. The interstory drift limits related to the performance levels defined by the Turkish Bridge Seismic Design Code 2020 were determined by the incremental dynamic analysis method, and fragility curves were obtained using 10 different earthquake records based on these determined limits. The results showed that the target performance level Uninterrupted Occupancy and Collapse Prevention performance level requirements, as defined by the Turkish Bridge Seismic Design, were not met, and the Collapse Probability is %100. Full article