Search Results (596)

Throughout the service life, bridge structures may face blast hazards from military conflicts, terrorist attacks, and accidental explosions. Dynamic responses and damage modes of box girder bridges with corrugated steel webs under blast loading remain scarce. This study investigates the dynamic response and optimal design of box girder bridges with corrugated steel webs under blast loading. A box girder bridge model with corrugated steel webs is established through the software LS-DYNA, and the dynamic response of the bridge model subjected to blast loads is studied. Parametric studies are conducted to evaluate the effects of key geometric parameters, including the folding angle, height–span ratio, and dip angle of corrugated steel webs, on the blast-resistance performance of the bridge. The results indicate that a folding angle of 55° provides optimal blast resistance by balancing local stiffness and stress concentration. The 3.0 m height of corrugated steel webs maximizes the energy absorption capacity of corrugated steel webs while minimizing mid-span residual deflection. A dip angle of 85° ensures effective deformation constraint and load transfer, reducing damage in both the upper and bottom bridge decks. This study highlights the critical role of corrugated steel web geometry in enhancing blast resistance and provides practical guidelines for optimizing the design of box girder bridges with corrugated steel webs under extreme loading conditions. Full article

To mitigate thermal cracking in concrete box girders during construction, this study introduces an inversion method for thermal parameters by integrating machine learning with finite element simulation. The research aims to accurately identify key thermal parameters—thermal conductivity k, total hydration heat Q₀, convection coefficient h, and reaction coefficient m—through an efficient and reliable data-driven approach. An orthogonal experimental design was used to construct a representative sample database, and a Bayesian-optimized XGBoost (BO-XGBoost) model was developed to establish a nonlinear mapping between temperature peaks and thermal parameters. Validated against field monitoring data from a prestressed concrete continuous rigid-frame bridge, the method demonstrated high accuracy: the inversiontemperature curves closely matched measured data, with a maximum peak temperature error of only 1.40 °C (relative error 2.5%). Compared to conventional machine learning models (DT, SVR, BP and LSTM), BO-XGBoost showed superior predictive performance and convergence efficiency. The proposed approach provides a scientific basis for real-time temperature control and crack prevention in concrete box girders and is applicable to temperature field analysis in mass concrete structures. Full article

This paper presents a static-strength analysis of the construction of folding bridges, addressing in particular the dimensioning of pin connections. These connections are elements that transfer the axial forces between the chords of truss girders of connected span sections. First, the various components of folding bridges and the materials from which they are made are characterised. The characteristics of pin connections in modern folding bridge structures are discussed, including their influence on the static scheme of the entire structure. The parameters of such pin connections are presented in terms of both the strength of such a connection and cooperation of its components. The main part of this article is a detailed design analysis of the pin connection of the new MSC 23-150 “Cis” folding bridge structure, the concept of which was developed at the Faculty of Civil Engineering and Geodesy of the Military University of Technology. The calculations were carried out both analytically and with a spatial numerical model, which allowed us to determine the stresses on the connection components in the critical sections and propose the final shape of the connector. This article presents the effect of combining known methods of dimensioning pin connections and a method related to determining actual stress values by taking into account the so-called stress concentration factor in analytical calculations. Taking into account the real area of impact of the pin on the bridge pin joint element affects the stress concentration, which can cause an increase in stress in selected cases by up to 300%. Original results are presented on the relationship between individual stress values in specific cross-sections of the connection and the values of assembly clearances in prefabricated bridge structures, as well as their mutual relationships for specific values of assembly clearances. The above information is important when developing and operating bridges made of portable truss-type bridge structures. Knowledge of the phenomenon of stress concentration reduction when limiting assembly clearance allows for the safe and effective use and construction of this type of bridge structure. Full article

This study develops a computational framework for the simultaneous quantification of seismic resilience and economic losses in corrosion-affected coastal continuous girder bridges. The proposed model integrates adjustment factors to reflect delays in post-earthquake repairs and cost increments caused by progressive material degradation. Finite element methods and nonlinear dynamic time-history simulations were conducted on an existing coastal continuous girder bridge to validate the proposed model. The key innovation lies in a probability-weighted resilience index incorporating damage state occurrence probabilities, which overcomes the computational inefficiency of traditional recovery function approaches. Key findings demonstrate that chloride exposure duration exhibits a statistically significant positive association with earthquake-induced structural failure probabilities. Sensitivity analysis reveals two critical patterns: (1) a 0.3 g PGA increase causes a 11.4–18.2% reduction in the resilience index (RI), and (2) every ten-year extension of corrosion exposure decreases RI by 2.7–6.2%, confirming seismic intensity’s predominant role compared to material deterioration. The refined assessment approach reduces computational deviation to ±2.4%, relative to conventional recovery function methods. Economic analysis indicates that chloride-induced aging generates incremental indirect losses ranging from $58,000 to $108,000 per decade, illustrating compounding post-disaster socioeconomic consequences. This work systematically bridges corrosion-dependent structural vulnerabilities with long-term fiscal implications, providing decision-support tools for coastal continuous girder bridges’ maintenance planning. Full article

In lateral-joint-widening projects of multi-span continuous concrete box girder bridges, significant discrepancies in longitudinal shrinkage, creep deformation, and vertical displacement between the existing and newly added bridge sections can lead to stress concentration and subsequent concrete cracking. Notably, such incompatibility often results in pronounced overall lateral bending deformation, which compromises the structural safety and service reliability of the widened bridge. To address these challenges, this study proposes a novel sliding-type transverse connection structure. This innovative connection enables the independent development of longitudinal shrinkage and creep deformation in the new bridge superstructure relative to the old one through a sliding mechanism, thereby effectively mitigating stress concentration and minimizing overall bending deformation caused by differential deformations. To validate the feasibility and elucidate the load transfer mechanism of the proposed structure, both scaled model tests and finite element simulations were conducted. The results indicate that the connection not only effectively coordinates longitudinal deformation differences and accommodates vertical deformation between the flange plates of the new and old bridges, but also ensures efficient transverse load transfer through shear force transmission. The structural behavior is primarily governed by shear stress distribution. These findings demonstrate that the sliding-type transverse connection significantly improves deformation compatibility in bridge widening applications, thereby enhancing the mechanical performance and safety reliability of the overall structure. Full article

Explosions pose significant risks to large-span steel bridges, which are integral to modern transportation networks and construction projects. This study evaluates the blast resistance of the orthotropic bridge deck of the Taizhou Yangtze River Bridge using numerical simulations validated by explosion tests. Five vehicular bomb scenarios, as specified by the Federal Emergency Management Agency, were analyzed to understand the damage mechanisms under above-deck explosions. Results show that all scenarios cause petal-shaped openings in the top plate, fractures in U-stiffeners, and plastic deformation in diaphragms. Larger TNT masses lead to additional failures, such as outward bending and bottom plate openings. Energy dissipation primarily occurs through plastic deformation and failure of various deck components, with the extent depending on the TNT mass. The vehicle shell significantly reduces damage for smaller charges (454 kg TNT) but has a minor effect for larger charges (>4536 kg TNT). This research enhances the understanding of blast resistance in orthotropic steel decks, a key component in modern bridge construction, and informs practices for designing resilient structures. Full article

For an existing bridge constructed with separate spans, the ends of adjacent flanges are disconnected. The problem of separated driving may occur at the bridgehead position after traffic conversion. The idea of integral splicing two separate spans of the existing long-span bridge is proposed. Direct crossing of a vehicle between the two separate spans of the existing long-span bridge can be realized. Firstly, the demand for integral splicing of the existing box girder bridge is analyzed using different methods. Then, an integral splicing composite structure (ISC-Structure) is designed and tested, and the corresponding design method is summarized. Finally, the construction technology for the ISC-Structure is optimized based on the actual field conditions. This research shows that the integral splicing demand of the old bridge can be obtained through on-site monitoring at the splicing position. Furthermore, the proposed random traffic flow simulation method can be applied to expand the data volume and verify the validity of the monitoring data. The proposed ISC-Structure meets the transverse splicing requirements of the Xinfengjiang Bridge. It can effectively connect the two separate spans, enabling them to work compositely and improving longitudinal mechanical properties. A layered and segmented construction scheme is proposed, and the relevant construction technology is optimized for the target integral splicing project. The proposed integral splicing design and construction technology can sever as a reference for similar long-span bridge extension projects. Full article

A significant aerodynamic interference effect exists between parallel bridges. In this study, a proposed long-span cable-stayed bridge, near which is an existing truss-arch bridge, was considered as the background. The wind characteristics at the proposed bridge site and the wind-induced responses of the bridge deck were investigated with and without the influence of an upstream bridge. The results showed that under aerodynamic interference of the upstream bridge, the downstream bridge site exhibited a noticeable change in the mean wind speed profile within the height range of the main girder and arch. The turbulence intensities significantly increased, especially for u and w components. The integral scales decreased remarkably, and the wind speed spectra redistributed toward higher frequencies. For the wind-induced responses, the mean displacements of the downstream bridge all decreased; in contrast, the buffeting and peak displacements all increased in both the maximum single cantilever state and the completed state, while the variation in buffeting response was much more significant and dominated the peak response. Moreover, under the interference of the upstream bridge, the buffeting displacement spectra redistributed toward high frequencies. This research acts as an effective tool for achieving secure bridge design and finding a better balance between design constraints. Full article

The abnormal tension change in one cable in a cable-stayed bridge indicates cable damage, so it is necessary to obtain the benchmark of the cable tension. After establishing the regression model of the mapping between the temperature-induced cable tension and the bridge temperature field or other data, the regression value can be used as the benchmark. To improve the regression model, the geometric compatibility and mechanical equilibrium must be jointly considered. Therefore, two data groups, which contain the bridge temperature field and the regression values of the temperature-induced deflection of the main girder, are input into the deep learning neural networks. Time lags exist between the temperature features and the temperature-induced cable tension, but are not significant between the temperature-induced deflection and tension. So one neural network module, which receiving the regression values of the temperature-induced deflection, is composed of Convolutional Neural Networks (CNNs). The other neural network module, which receives the temperature features, is composed of stacked CNN and Long Short-Term Memory (LSTM). Finally, several convolution kernels will integrate the array output from the two modules into one regression value of the temperature-induced cable tension. By combining the input data and the composite neural networks, the R² of the regression models of the temperature-induced cable tension is more than 0.95, and the error of the regression values is less than 0.3 kN. In the future, if the nonlinearity at the curve inflection point and the complexity in data distribution could be solved, the stability of the model may be improved. Full article

Ultra-high-performance concrete (UHPC) exhibits significantly superior compressive and tensile properties compared to conventional concrete, demonstrating substantial application potential in bridge engineering. This study conducted full-scale bending tests on a 30 m prestressed UHPC-NC composite box girder within an actual engineering context. The testing flexural capacity $M_t=\mathrm{34,469.2} \mathrm{k}\mathrm{N}·\mathrm{m}$ exceeded the design requirement $M_d=\mathrm{18,138.0} \mathrm{k}\mathrm{N}·\mathrm{m}$, with $M_t/M_d=1.90$. Finite element modeling (FEM) was employed to analyze and predict experimental outcomes, revealing a simulated flexural capacity of approximately 37,597.1 $\mathrm{k}\mathrm{N}·\mathrm{m}$. The finite element models further explored failure mode transitions governed by the loading position while the concentrated load-to-support distance exceeds 9.62 m (shear span to effective depth ratio λ = 6.3), and the box girder fails in flexure; while less than 9.62 m, the box girder fails in shear. The flexural capacity of the test girder was also estimated using Response-2000 software and the recommended formulas from the Chinese code T/CCES 27-2021 (Technical specification for ultra-high-performance concrete girder bridge). The Response-2000 software yielded a flexural capacity estimate of $M_r=\mathrm{30,816.1} \mathrm{k}\mathrm{N}·\mathrm{m}$. The technical specification provided two estimating results: (with safety factors) $M_{u1}=\mathrm{25,414.4} \mathrm{k}\mathrm{N}·\mathrm{m}$ and (without safety factors) $M_{u2}=\mathrm{33,810.9} \mathrm{k}\mathrm{N}·\mathrm{m}$. All estimated values of Response-2000 and Chinese code were rationally conservative ($M_r,{ M}_{u1}, M_{u2}<M_t$). Comparative analysis demonstrates that Abaqus FEM accurately simulates the flexural behavior of the prestressed UHPC-NC composite box girders. Both Response-2000 calculations and the Chinese code T/CCES 27-2021 provide critical references for similar applications of prestressed UHPC-NC composite box girders. Full article

Thermal effects critically influence the design and construction of steel-concrete composite cable-stayed bridges, where material thermal mismatch complicates structural responses. Current code-specified temperature gradient models inadequately address long-span bridges. This study employs in-situ monitoring of the Chibi Yangtze River Bridge to propose a refined vertical temperature gradient model, utilizing an exponential function for the concrete deck and a linear function for the steel web. Finite element analysis across six construction stages reveals: (1) Under negative temperature gradients, the concrete deck develops tensile stresses (2.439–2.591 MPa), approximately 30% lower than code-predicted values (3.613–3.715 MPa), highlighting risks of longitudinal cracking. (2) At the maximum double-cantilever stage, transverse stress distributions show pronounced shear lag effects, positive shear lag in deck sections connected to crossbeams and negative shear lag in non-connected sections. The proposed model reduces tensile stress conservatism in codes by 30–33%, enhancing prediction accuracy for composite girders. This work provides critical insights for thermal effect management in long-span bridge construction. Full article

In recent years, the deterioration of social infrastructure such as bridges has become a serious issue in many countries around the world. To maintain the functionality of aging bridges over the long term, it is necessary to conduct regular inspections, detect damage at an early stage, and perform timely repairs. However, inspections require significant cost and time, and ensuring the safety of inspectors remains a major challenge. As a result, inspection using robots has attracted increasing attention. This study focuses on a wire-driven bridge inspection robot designed to inspect the underside of bridge girders. To use this robot, wires must be installed in the space beneath the girders. However, it is difficult to install wires over areas such as rivers. To address this problem, we developed a robotic arm capable of throwing a spear attached to a string. In order to throw the spear accurately to the target location, a three-dimensional dynamic model of the spear in flight was constructed, considering the tension of the string. Using this model, we accurately estimated the required throwing conditions and confirmed that the robotic arm could successfully throw the spear to the target location. Full article

The main objective of this research is to investigate the impact of the tendon profile layout on the shear strength of unbonded post-tensioned prestressed concrete bridge I-girders. This study involves an experimental investigation where ten unbonded post-tensioned bridge girders are cast and subjected to four-point loads. The focus of the investigation is on the effect of different tendon profile layouts, including trapezoidal, parabolic, and harped shapes. The experimental results reveal that the shear behavior of the specimens progresses through three distinct stages: the elastic stage, the elastic–plastic stage, and the plastic stage, with all specimens ultimately failing due to shear. The results show that tendon profiles with higher eccentricity at the end of the beams (80 mm above the neutral axis) had the highest ultimate load capacity for each tendon profile shape, coupled with the largest deflection. Conversely, profiles with lower eccentricity (80 mm below the neutral axis) demonstrated the lower ultimate load capacity for each tendon profile shape and minimal deflection. Among the various tendon profile layouts that were tested, the specimen with the harped tendon profile (GF-1 HA) showed the highest ultimate load capacity, with an increasing rate of 17.52% in ultimate load and a 45.55% increase in ultimate deflection compared to the control beam (GF-1 ST) with a straight tendon profile. On the other hand, the harped tendon profile specimen (GF-1 HA) exhibited the lowest deflection among the various tendon profile shapes with an increasing rate of 5.7% in ultimate load deflection in comparison with the control beam (GF-1 ST) with a straight tendon profile. These improvements in stiffness, load capacity, and deflection are attributed to enhanced resistance, particularly at the supports. Consequently, the optimized tendon layouts offer an increase in the overall structural efficiency, leading to potential cost savings in bridge girder production. Full article

The study presents an analysis of steel-Ultra-High Performance Concrete (UHPC) composite girders. Five composite girder specimens were designed and tested. Analytical strain solutions for the composite girders under asymmetric axial loading were derived using the energy variation method. Results indicate that asymmetric axial forces significantly exacerbate the shear lag effect. Decreasing the width-to-span ratio reduces the shear lag coefficient, while reducing the width-to-depth ratio increases it. The parametric analysis indicates that, under asymmetric axial loading, increasing the strength of the concrete is an effective method to reduce the shear lag effect of the composite girders. Increasing the thickness of the UHPC slab proves to be effective in reducing the shear lag effect. Furthermore, the study indicates that when the b₂/b₁ ratio is less than 1, it has a tiny impact on the shear lag effect; however, when the b₂/b₁ ratio is greater than 1, the shear lag effect becomes more pronounced with increasing b₂/b₁. Additionally, the thickness of the flange plate and web plate of the steel girder has no significant effect on the shear lag effect. The results of the analysis can provide references for similar designs and constructions of composite structures. Full article

The temperature field distribution and temperature effects of concrete box girder bridges were found to be critical to their long-term service safety. Based on long-term structural health monitoring data, the temperature field and temperature effects of a curved continuous concrete box girder bridge in Wuhan were investigated. A finite element model of the temperature field was established through the combined application of finite element software. Extreme weather files were constructed to analyze the bridge’s temperature field and temperature effects. To enhance data reliability, wavelet analysis was employed for denoising the monitoring data. The results indicate a strong correlation between girder temperature and ambient temperature. Under solar radiation, significant vertical temperature differences and certain lateral temperature differences are observed within the concrete box girder. The accuracy of the finite element model was validated through comparison with measured data. Temperature field models featuring the most unfavorable vertical and transverse temperature gradient distribution patterns for concrete box girder bridges under extreme weather conditions in the Wuhan region were established. A distinct temperature difference not covered by specifications exists at the webs and bottom slabs of the bridge. Strong correlations were observed between both pier–girder relative displacement and bottom slab stress with the girder temperature. Full article