Concrete Girder Bridges Research Articles

A GIS Plugin for the Assessment of Deformations in Existing Bridge Portfolios via MTInSAR Data

The paper presents a GIS plugin, named Bridge Assessment System via MTInSAR (BAS-MTInSAR), aimed at assessing deformations in existing simply supported concrete girder bridges through Multi-Temporal Interferometry Synthetic Aperture Radar (MTInSAR). Existing bridges require continuous maintenance to ensure functionality toward external effects undermining the safety of these structures, such as aging, material degradation, and environmental factors. Although effective and standardized methodologies exist (e.g., structural monitoring, periodic onsite inspections), new emerging technologies could be employed to provide time- and cost-effective information on the current state of structures and to drive prompt interventions to mitigate risk. One example is represented by MTInSAR data, which can provide near-continuous information about structural displacements over time. To easily manage these data, the paper presents BAS-MTInSAR. The tool allows users to insert information of the focused bridge (displacement time series, structural information, temperature data) and, through a user-friendly GUI, observe the occurrence of abnormal deformations. In addition, the tool implements a procedure of multisource data management and defines proper thresholds to assess bridge behavior against current code prescriptions. BAS-MTInSAR is fully described throughout the text and was tested on a real case study, showing the main potentialities of the tool in managing bridge portfolios.

Effect of Non-Uniform Temperature Distribution on the Natural Frequency of Concrete Girder Bridges

Structural dynamic properties like frequencies and mode shapes have been widely adopted for bridge condition assessment and damage identification. One of the main challenges lies in environmental factors, particularly the varying temperature, which significantly influences the bridge’s natural frequencies. In some cases, the effect of temperature changes can be comparable to, or even exceed, the effect caused by damage, rendering the damage identification methods ineffective. This study investigates the influence of the cross-sectional non-uniform temperature distribution, as a result of surrounding environmental factors, on the frequency of concrete girder bridges. A theoretical analysis is conducted to derive the bridge’s frequencies considering the cross-sectional non-uniform temperature distribution. The upper and lower bounds of the frequencies are developed by using only the environmental temperature and the largest temperature gradient defined by codes. More importantly, the damage to the bridge can be detected if the frequencies exceed the bounds for a certain period. This approach is convenient and practical in real applications without embedding thermocouples in the main girder. Numerical simulations, laboratory experimental tests, and field measurements are carried out to validate the derived frequency considering the cross-sectional non-uniform temperature distribution as well as the upper and lower bounds of the frequency. In particular, the results of the Z24 bridge show that when the bridge is damaged, the measured frequency exceeds the bound continuously, verifying the capability of the developed upper and lower bounds to evaluate bridge conditions.

An automated load determination approach for concrete girder bridges through acoustic emission

An automated load determination approach for concrete girder bridges through acoustic emission

Acoustic emission monitoring of a large-scale 50-year-old prestressed concrete bridge girder during an eccentric three-point bending test

Deterioration of reinforced and prestressed concrete structures is one of the main challenges in structural engineering. As the majority of our infrastructure is built around 1960-1980, most structures have reached or will soon reach their design lifetime, giving rise to more structural problems and costs in the coming decades. It is therefore important to develop efficient assessment schemes allowing to assure the safety and reliability of these existing structures and to estimate their residual lifetime. Within the framework of the Bridge|50 research project, a 50-year-old prestressed concrete bridge showing signs of corrosion damage was decommissioned. The bridge girders were recovered and have been subjected to large-scale load tests with varying loading patterns. This paper presents the results acquired during acoustic emission (AE) monitoring of one of the I-shaped girders during a monotonic three-point bending test with an eccentric point load. The results show that the failure mode and location could be detected based on AE activity and zonal AE localization. The onset of concrete cracking was observed by a decrease in peak frequency of the AE signals. Average frequency (AF) and rise angle (RA) value analysis was used to characterize the crack mode, which shifted from tensile to shear mode during bending.

Analytical Investigation of Fatigue Behavior in a Modified Composite Steel Box Concrete Girder Bridge with Corrugated Steel Webs under Pavement and Expansion Joint Deterioration

Analytical Investigation of Fatigue Behavior in a Modified Composite Steel Box Concrete Girder Bridge with Corrugated Steel Webs under Pavement and Expansion Joint Deterioration

Enhancing structural damage evaluation of PC girder bridges through digital twinning Bayesian model updating

Developing a unified analytical framework to assess the structural performance of deteriorated prestressed concrete (PC) girder bridges is important for their maintenance. This study aims to construct a physics-based digital twin framework for PC girder bridges incorporating Bayesian model selection and updating, a high-fidelity three-dimensional (3D) finite element (FE) model, and a method for simulating prestressed tendon damage. In this study, three PC girder specimens were designed and tested to evaluate the effects of tendon rupture near the anchorage region on structural performance. Bayesian model selection was used to determine the most plausible model class based on the estimated model evidence. The most probable values (MPVs) of the model parameters, derived from the estimated posterior probability density functions (PDFs), were then used to calibrate the FE model, which reflects a healthy state of the PC girder bridge. This updated FE model serves as the baseline for conducting what-if scenario simulations. Subsequently, nonlinear segments of the constitutive model, obtained from coupon tests, and a simulation method for tendon rupture were incorporated into the updated FE model. Nonlinear static simulation results obtained through the updated model were found to be consistent with both the observed crack pattern and the load–deflection curve. The reliability of the digital twinning FE model for assessing tendon damage and for predicting the residual load-bearing capacity was verified through comparison with measured data. Therefore, the digital twinning Bayesian model updating approach shows potential applications in continuous structural health monitoring (SHM) of PC bridges.

Calculation method of temporary cable force in incremental launching construction of large span steel box girder without auxiliary pier

The Fenshui River Bridge is a steel–concrete composite girder bridge with a main span of 90 m. Due to the topographical constraints, the steel box girder was constructed without the use of auxiliary piers, employing incremental launching techniques. This article focuses on the construction technology used for the steel box girder of the Fenshui River Bridge. Firstly, using the influence matrix method, the cable force is determined based on the maximum cantilever state of the structure, with the vertical deformation of the front end of the guide beam and the horizontal deformation of the top of the tower as the control objectives. The unstressed cable length is then calculated based on the mechanical relationship between cable deformation and cable force. A calculation method for adaptive cable force is proposed, which is based on the variation of the stress-free cable length within the adaptive structural system. Next, the finite element analysis method was employed to determine the optimal layout position for the tower. The results indicate that during the incremental launching construction of the steel box girder, the calculated cable forces using the method proposed in this paper are in close agreement with the measured cable forces. At the maximum cantilever state of the structure, the calculated and measured values of the cable force resulted in a percentage difference of 3.96%. The calculated values of deformation and stress in key sections showed a percentage difference of 6.4% for deformation and 6.6% for stress. To maximize the effectiveness of the tower and cable, the tower should be positioned above the bridge pier when the guide beam crosses the maximum span. The findings of this paper can serve as a reference for the construction of similar types of bridges.

Data-driven study on shear bearing capacity of segmental concrete joints

Segmental assembly joints with excellent shear bearing capacity are the key to ensure the integrity of precast concrete girder bridges, which directly affects the force transmission state of the girders. However, with the existence of unfavorable factors such as the multi-key shear capacity reduction effect, the traditional prediction model for calculating the concrete joints shear capacity has poor prediction accuracy and large dispersion. To overcome the shortcomings of the existing prediction model, this study established a database consisting of 311 sets of test data and 110 sets of numerical results based on existing research. A total of seven data-driven models for predicting shear capacity of concrete joints were trained and generated based on the database, namely, two linear models (Linear Regression Support Vector Machine Algorithm, Least Squares Linear Regression) and five nonlinear models (Neural Network Bayesian Regularization; Neural Network Quantized Conjugate Gradient Model, Neural Network Levenberg-Marquardt (LM), Decision Tree, and Gaussian regression). The coefficient of determination (R2), root mean square error (RMSE)，mean absolute error (MAE), error range (A20-index), and error analysis were adopted to evaluate those model's performance. The evaluation results show that the LM model has excellent prediction accuracy, stability, robustness, and can guide the engineering design. Finally, the established database (421 data sets) and trained LM algorithm model were open sourse in this study to promot the investigate of precast concrete structures.

Study on Vibration and Noise of Railway Steel–Concrete Composite Box Girder Bridge Considering Vehicle–Bridge Coupling Effect

A steel–concrete composite beam bridge fully exploits the mechanical advantages of the concrete structure and steel structure, and has the advantages of a fast construction speed and large stiffness. It is of certain research value to explore the application of this bridge type in the field of railway bridges. However, with the rapid development of domestic high-speed railway construction, the problem of vibration and noise radiation of high-speed railway bridges caused by train loads is becoming more and more serious. A steel–concrete composite beam bridge combines the tensile characteristics of steel and the compressive characteristics of concrete perfectly. At the same time, it also has the characteristics of a steel bridge and concrete bridge in terms of vibration and noise radiation. This feature makes the study of the vibration and noise of the bridge type more complicated. Therefore, in this paper, the characteristics of vibration and noise radiation of a high-speed railway steel–concrete composite box girder bridge are studied in detail from two aspects: the theoretical basis and a numerical simulation. The main results obtained are as follows: Relying on the idea of vehicle–rail–bridge coupling dynamics, a structural dynamics analysis model of a steel–concrete combined girder bridge for a high-speed railroad was established, and numerical program simulation of the vibration of the vehicle–rail–bridge coupling system was carried out based on the parametric design language of ANSYS 18.0 and the language of MATLAB R2021a, and the structural vibration results were analyzed in both the time domain and frequency domain. By using different time-step loading for the vehicle–rail–bridge coupling vibration analysis, the computational efficiency can be effectively improved under the condition of guaranteeing the accuracy of the result analysis within 100 Hz. Based on the power flow equilibrium equation, a statistical energy method of calculating the high-frequency noise radiation is theoretically derived. Based on the theoretical basis of the statistical energy method, the high-frequency noise in the structure is numerically simulated in the VAONE 2021 software, and the average contribution of the concrete roof plate to the three acoustic field points constructed in this paper is as high as 50%, which is of great significance in the study of noise reduction in steel–concrete composite girders.

Nonlinear Finite-Element Modeling of Concrete Bridge Girders Prestressed with Carbon Fiber–Reinforced Polymers

Nonlinear Finite-Element Modeling of Concrete Bridge Girders Prestressed with Carbon Fiber–Reinforced Polymers

Structural Health Monitoring at Single-span Prestressed Concrete Girder Bridge by Ambient Vibration Measurement and Identification Modal Frequency

Structural Health Monitoring at Single-span Prestressed Concrete Girder Bridge by Ambient Vibration Measurement and Identification Modal Frequency

Condition assessment of prestressed concrete channel bridge girders using acoustic emission and data-driven methods

In the United States, a significant proportion of bridges are contending with aging and decay, necessitating reliable inspection methods for ensuring safety and functionality. Traditional visual inspections, while common, are often subjective and labor-intensive. This study proposes an innovative approach using Structural Health Monitoring (SHM) systems, particularly focusing on Acoustic Emission (AE) techniques. AE is chosen for its sensitivity to the early stages of material damage. The research involves flexural tests on six prestressed concrete channel bridge girders from 30-ft span bridges, originally constructed in the 1960s, at the University of South Carolina. These girders were monitored using AE during tests and were previously rated for condition based on the Specifications for the National Bridge Inventory (SNBI). The contribution of this paper is the development of intensity analysis charts from AE data, offering a more objective and comprehensive assessment of girder conditions. These charts, calibrated against theoretical cracking load and cumulative signal strength analysis, are capable of evaluating deterioration irrespective of initial conditions, thereby aiding in determining the condition factor for bridge load rating.

Prestressed concrete continuous bridge girders: comparison of the Chinese and Southern African codes

To provide a reference for designers, taking a 30 m + 40 m + 30 m prestressed concrete continuous beam bridge as an example, this paper compares the differences between Chinese Codes and Southern African Codes in terms of load effect, prestressing requirements and design safety. The results show that the actual number of prestressed strands required by the Southern African Code in the mid-span section is 11.63 %-12.50 % larger than that required by the Chinese Code. The actual number of prestressed strands required by the Southern African Code in the fulcrum section is 16.33 %-30.00 % lower than that required by the Chinese Code. The safety margin factor of the section designed by the Southern African Code is higher than that of the Chinese Code, and has a higher safety reserve.

Hierarchical and mixed uncertainty quantification for simulation-based structural seismic fragility analysis

Seismic fragility assessments (SFA) encompass significant uncertainties, including ground motions, materials, geometry, boundaries, and modeling, which impart inherent uncertainties to the fragility curve. Quantifying these uncertainties is essential for informed decision-making in earthquake disaster mitigation. This paper presents a hierarchical uncertainty quantification (UQ) framework for simulation-based SFA, which can address mixed aleatory and epistemic uncertainties. The framework comprises two levels: At Level 1, ground motion uncertainties are accounted for through record-to-record variation, while structural parameter uncertainties are captured using well-defined probability distributions. The quantification of uncertainty in seismic fragility is accomplished using mean and quantile fragility curves, representing the average outcome and the dispersion of structural fragility, respectively. Fuzziness is also introduced to enhance the objectivity of failure determination. Level 2 addresses uncertainties in the distribution hyper-parameters of structural variables through evidence theory, facilitating an understanding of their influence on the seismic fragility curve and quantifying uncertainty in mean and quantile fragility curves. This UQ framework builds upon the multivariate seismic fragility analysis method, integrating Kriging regression for seismic demand prediction and logistic regression for generating multivariate seismic fragility functions. The proposed framework is validated numerically on an existing three-span reinforced concrete continuous girder bridge, affirming its practical utility and reliability.

Domain knowledge-enhanced region growing framework for semantic segmentation of bridge point clouds

Utilising domain knowledge (DK) to semantically segment bridge point clouds has attracted growing research interest. However, current approaches are often tailored to specific bridges, limiting their general applicability. To address this problem, this paper introduces a DK-enhanced Region Growing (DKRG) framework for point cloud semantic segmentation of reinforced concrete (RC) girder bridges. Inspired by the vertical layout characteristics of bridges, the generation of DK-based point features from Finite Element Analysis (FEA) is first proposed. Then, DKRG is employed to segment bridge components from substructures to superstructures by leveraging an “easy-to-difficult” strategy. Validation results demonstrate the effectiveness of our method, achieving the lowest mean Intersection over Union (mIoU) of 95.47% for the entire bridge and 93.44% for different component types. This study provides a new DK-based framework for semantic segmentation of RC girder bridges and sheds new light on using FEA-generated point features.

Full-scale experimental investigation of prestressed concrete bridge girders strengthened with aluminium channels

The bridge network in South Carolina encompasses more than 9,000 structures, many of which were originally constructed to accommodate H10 (89 kN) or H15 (134 kN) truck loads and thus require strengthening to carry current loading standard (HL-93). The South Carolina Department of Transportation (SCDOT) has recognized that prestressed concrete channel bridge girders, a specific type of bridge superstructure, often face challenges in achieving adequate load ratings, based on flexural strength. Hence, it is imperative to explore strengthening methods for these girders. Aluminium alloys possess desirable properties that make them attractive as external reinforcement materials. While previous studies have investigated the use of aluminium alloys on small-scale reinforced concrete members, there is a lack of investigation on their use on full-scale prestressed concrete bridge girders. To address this gap, this study investigates the feasibility of utilizing aluminium alloy channels as an external reinforcement material on full-scale prestressed concrete channel bridge girders. The main goal of this paper is to propose a strengthening method for prestressed concrete channel girders that is cost effective and easily implemented in the field to reduce the number of load-posted bridges in the state of South Carolina. Nine girders from recently decommissioned bridges in South Carolina were tested under flexural loading conditions to failure. The test program consisted of six unstrengthened girders, one strengthened with bonded aluminium channels (SE), one strengthened with bonded and bolted aluminium channels (SEB), and one strengthened with bolted aluminium channels (SB). Before testing, a visual inspection of the girders was conducted to identify any existing deterioration, and each girder was given a condition rating based on the Specifications for the National Bridge Inventory (SNBI). Theflexuralicate that externally anchored aluminium alloy channels with bolts was the most effective strengthening method in terms of practicality and increase in the flexural strength. Moreover, the results also revealed that the measured flexural strength of the girders varied based on the extent of the observed girder deterioration.

Comparative Study on the Seismic Vulnerability of Continuous Bridges with Steel–Concrete Composite Girder and Reinforced Concrete Girder

For medium- and small-span bridges, the weight of the superstructure in steel–concrete composite girder bridges is lighter than that of a reinforced concrete girder bridge. However, it is still uncertain whether steel–concrete composite girder bridges exhibit superior seismic performance compared to reinforced concrete girder bridges. This study quantitatively compared the seismic performance of the two types of bridges. Using the theory of probabilistic seismic demand analysis, the seismic vulnerability curves of bridges were derived. To conduct seismic demand analysis for probabilistic analysis on the OpenSEES platform, bridge samples were generated using the Latin hypercube stratified sampling method, which considers the uncertainties associated with the two types of bridges. The vulnerability curves of the piers, bearings, abutments, and the system of the two bridges were established using probabilistic analysis of the time history analyses. The results showed that the seismic vulnerabilities of components and the overall system of the steel–concrete composite girder bridge were both lower than those of the reinforced concrete girder bridge. When the peak ground acceleration (PGA) of the ground motion was 0.3 g, the moderate and serious damage probabilities of the piers in the steel–concrete composite bridge were only 54.61% and 60.89%, respectively, of those of the reinforced concrete bridge. Consequently, replacing the upper reinforced concrete girders with steel–concrete composite girders can significantly improve the seismic performance of a large number of existing bridges.

Corrosion-induced fragility of existing prestressed concrete girder bridges under traffic loads

Italian and European transportation networks include a significant number of existing bridges, built since the early ‘60s, characterised by simply supported prestressed concrete (PC) girders with post-tensioned steel tendons. Corrosion of tendons, which may lead to significant loss of structural capacity, cannot be detected by simple visual inspections and requires advanced and expensive testing by bridge owners. Therefore, procedures aimed at risk-informed prioritisation of advanced inspections and possibly retrofit are needed. The paper presents a study on the fragility of existing PC girder bridges considering traffic loads, accounting for corrosion-induced effects. An automated framework is proposed, aiming at the efficient probabilistic structural assessment of the investigated bridge typology accounting for different critical corrosion scenarios and the influence of knowledge-based uncertainty related to geometric and mechanical properties. To simulate corrosion effects, prestressing steel tendon geometric and mechanical characteristics are modified through a specific algorithm able to estimate variations in flexural and shear bearing capacity of critical cross-sections. To simulate the traffic loads, a simplified analysis is performed by using code-based traffic load models. In the paper, the framework is tested with reference to a dataset of case-study superstructures. The obtained fragility curves are deeply discussed, highlighting the effects of the number of girders and span length on the corrosion-induced increase in fragility. Although the proposed methodology presents some simplifications, it could improve the current practices of risk prioritisation, by supporting transportation authorities in ensuring the safety of the existing bridge stock.

Push-Out Analysis on the Shear Performance of a New Type of Bellow-Sleeved Stud

For continuous steel–concrete composite girder bridges based on the post-combined method, the conventional rectangular group studs contribute to the isolation of the steel girder and the concrete slab before prestressing, leading to the majority of prestress forces being introduced to the concrete slab. However, rectangular-group stud holes cause the prestress forces to be unevenly distributed. In this study, a new type of bellow-sleeved stud (BSS) was developed to mitigate the weakening effects of rectangular group stud holes on the slab. A steel corrugated sleeve with a diameter of 60 mm was employed to cover the stud, which served as an internal formwork to prevent the concrete from bonding with the root of the stud. After prestressing was complete, the steel sleeve was filled with ultra-high-performance concrete (UHPC) to create a reliable combination between the concrete slab and the steel girder. To investigate the shear performance of this new type of connection, eight push-out test specimens were designed, and finite-element models were built. This study drew a comparison between the BSS and the ordinary headed stud (OHS). The research findings suggested that the BSS is subjected to less bending–shear coupling and offers a 4.5% increase in shear strength and a 31.9% increase in shear stiffness compared with the OHS. The study also analyzed the structural parameters influencing the shear performance of the BSS. It is found that the steel sleeve of the BSS has a negative effect on shear performance, but this can be mitigated by infusing high-strength material into the sleeve. Furthermore, the study examined the effect of construction quality on shear performance and suggested that sleeve deviation and grout leakage considerably reduced the shear performance of the BSS. Accordingly, strict control over the construction quality of the BSS is necessary.

Laboratory Evaluation of Concrete Bridge Girders Flexural Strengthened with Near-surface Mounted Titanium Alloy Hooked Bars

The use of near-surface mounted (NSM) titanium alloy bars (TiABs) has emerged as a potential solution to provide flexural strengthening to in-service, reinforced-concrete bridge girders with flexural strength deficiencies. An experimental program was performed to evaluate the behavior of large-scale, reinforced-concrete bridge girders using NSM TiABs with hooked ends for both positive- and negative-moment flexural-strengthening purposes. The experimental program involved testing four positive-moment strengthened specimens including one control specimen while also testing two TiAB types. Additionally, three negative-moment strengthened specimens were tested including one control specimen using one TiAB type. Specimens were strengthened in accordance with the AASHTO Guide for the Design of Near-surface Mounted Titanium Alloy Bars, and the requirements of ACI 318-19 were used to handle the effect of stress concentrations at TiAB termination locations. The test results indicate that flexural strengthening using NSM TiABs with hooked ends is effective when the effect of stress concentrations at the TiAB termination locations and the potential formation of inclined shear cracks in the flexural tension region are considered in the design. ACI 318-19, which has provisions to account for the impact of stress concentrations at internal reinforcement termination locations, should be used in addition to the AASHTO Guide for the Design of Near-surface Mounted Titanium Alloy Bars. Additionally, the two TiAB types that were evaluated provided similar flexural behavior and either type can be used to strengthen bridge girders.