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The examination of existing civil structures must be differentiated from designing new structures. To have sustainable and circular asset management, the behavior of these existing structures must be better understood to avoid unnecessary maintenance and replacements. Monitoring data collected through bridge load testing, structural health monitoring, and non-destructive tests may provide useful information that could significantly influence their structural-safety evaluations. Nonetheless, these monitoring techniques are often elaborate, and the monitoring costs may not always justify the benefits of the information gained. Additionally, it is challenging to quantify the expected information gain before monitoring, especially when combining several techniques. This paper proposes several definitions and metrics to quantify the information gained from monitoring data to better evaluate the benefits of monitoring techniques. A full-scale bridge case study in Switzerland is used to illustrate the information gain from multiple monitoring techniques. On this structure, static load tests, three years of strain monitoring, weigh-in-motion measurements, and non-destructive tests were performed between 2016 and 2019. The influence on structural-safety examination is evaluated for each combination of monitoring techniques. Results show that each technique provides unique information and the optimal combination depends on the selected definition of information gain. When data from monitoring techniques are combined, significant reserve capacity of the bridge is determined.

One of the common reasons for traffic disruptions and costly repairs or replacements of highway bridges is impact damage from inadequate vertical clearance or over-height vehicles. The current study diagnosed, and load rated an old impact-damaged non-composite steel girder bridge on IH-30 in Dallas, TX, with extensive deck delamination. Load testing and Non-Destructive Evaluation (NDE) employing Ground Penetrating Radar (GPR) and Impact Echo (IE) were used to evaluate the six-span bridge. Span one was simply supported, while the others were continuous. The IE scan of the deck surface revealed that approximately 40% of the concrete was severely delaminated. While the GPR scans indicated that the top rebar covers in the cast-in-place deck ranged from 38 to 64 mm for 62% of the deck area. Analysis of strain data from the load test showed that the girder neutral axes were in the web, demonstrating non-composite action between the deck and girders. An innovative approach was employed to load rate the deck and the girders by combining the NDE and load testing results following AASHTO procedures. Since the girders and the deck were unsafe for HS-20 loading per the Texas Department of Transportation's requirements, load posting, and urgent bridge rehabilitation were recommended.

Many countries worldwide face a common problem with the aging bridge infrastructure that is being demanded to carry increasing loads. With the cost and the difficulties associated with replacing and rehabilitating these bridges, it is necessary to make the most efficient use of the existing infrastructure. Proof load testing (PLT) proved to be a reliable non-destructive method to assess the bridge and reflect its actual behavior, especially the old bridges. The advancement on the Internet of Things (IoT) technology concerning sensors and data acquisition systems for sensing, collecting, and storing the data in conjunction with Finite Element Modeling has resulted in combining analytical models and field test results for better assessment of the bridge condition. It would be insightful to combine the field-testing data with Finite Element Modeling to optimize the outcomes from proof load tests. In this paper, the case of the I-39 Kishwaukee, a five-span twin post-tensioned segmental concrete box girder bridge, has been studied. Kishwaukee bridge was built in 1970. Several retrofits were carried out on the structure to solve the cracks and slippage at the shear key between the pier segment and the adjacent cantilever segment caused by non-hardened epoxy at the joint during the time of construction. In 2006, The Illinois Department of Transportation investigates the structural behavior of the bridge and determined that the crack growth along the webs is caused by principal tensile stresses higher than the code limits. Using the FEA, the model shows an estimated permanent strain of 85 µɛ caused by the dead load only at the shear key. This strain added to the strain caused by the HS20 truck live load led to a total strain of 180 µɛ higher than the strain corresponding to the modulus of rupture of the concrete (135 µɛ). A total estimated deflection of 3.84 in. at midspan of Span #3 caused by HS20 truck live load exceeded the AASHTO allowable limit for deflection (3.74 in). Since the bridge was deficient, IDOT decided to strengthen the structure using four–12 strands, 15 mm external post-tensioning tendons placed inside the box girders to reduce the shear forces acting across the webs. This paper illustrates a proof of four different trucks loading weights of 76 tons (167 k), 90 tons (200 k), 122 tons (268 k), and 136 tons (300 k) conducted on the bridge. Nine testing scenarios were successfully completed with a maximum of two testing trucks of approximately 136 tons (300 k). The data obtained from the field test (Measured strains near the pier, where shear and negative moment are critical, and at midspan, where the positive moment is crucial, and measured deflection profiles) were used to optimize a non-linear finite element model for the bridge. This paper provides a comprehensive guide on how to conduct load rating assessments based on the AASHTO MBE method for PLT. It outlines a step-by-step procedure for conducting field operations, implementing instrumentation, and interpreting test results. The data obtained from the field test are used to develop a Finite Element Model showing the impact of the recently introduced external post-tensioning tendons on the structural performance of the bridge. In conjunction with the FEA, this research demonstrated that the rehabilitation of Kishwaukee I-39 bridge using the post-tensioning system reduced the deflection by 88.72%, and minimized the principal tensile strain of the shear key by 80µɛ. Based on these findings, this paper provided a significant allowance for accommodating future traffic load increases on the Kishwaukee I-39 River bridge.

The questions raised about bridge performance are carried out by conducting physical bridge load testing and rating. The outcomes of bridge load testing are widely used to ensure bridge safety for the public when theoretical analysis cannot provide a sufficient conclusion of in-service performance. The research illustrates the load ratings and shear assessment of a 1976-built I-39 Kishwaukee bridge over the Kishwaukee River in Winnebago County, District 1, Illinois. Load ratings of the Kishwaukee twin post-tensioned concrete box girder bridges are governed mainly by the shear stresses located near the piers in combination with visible shear cracks exhibited at the joints around the shear key due to the inception of the cracks at the time of construction in single key joints. Proof of four different trucks loading weights of 76 tons (167 k), 90 tons (200 k), 122 tons (268 k), and 136 tons (300 k) were conducted on the bridge. Nine testing scenarios were successfully completed with a maximum of two testing trucks of approximately 136 tons (300 k). Half of the bridge was instrumented using vibrating wire strain gauges to measure the strains near the pier, where shear and negative moment are critical, and at midspan, where the positive moment is crucial. Furthermore, crackmeters were placed along the cracks near the shear key region to measure the crack opening during testing. Linear variable differential transducers (LVDTs) were placed at the critical Sect. (0.40L) of Span #5 to measure the deflection. The modified compression field theory (MCFT) is used to calculate the shear capacity along the joints considering the contributions of vertical and horizontal reinforcing steel, the prestressing Dywidag bars, and the effect of the external post-tension tendons. This paper illustrates a detailed procedure for Kishwaukee Bridge load rating, field operation, instrumentation, and interpretation of the test results to determine the bridge load rating based on the 2018 AASHTO Manual for Bridge Evaluation. Findings from this study demonstrated that there is no crack slippage across the web-cracked section, and the bridge’s concrete shear capacity remains strong and contributes to the bridge’s total shear capacity. This study also showed that the shear capacity of the bridge is 1.8 times stronger than the total applied shear force, concluding that the Kishwaukee I-39 bridge remains safe for future traffic load increases or higher truck loads.

PurposeThe application of reinforcing old bridges by adding external prestressed steel bundles is becoming more and more widespread. However, the long-term safety performance test of the strengthening method is rarely carried out. In this paper, the bearing capacity of a 420 m prestressed concrete (PC) continuous girder bridge after five years of strengthening is analyzed.Design/methodology/approachThe bridge model of the bridge structure and strengthening scheme is established by the finite element software of the bridge. The theoretical load-bearing capacity of the bridge under the latest standard load grade is obtained by finite element analysis. The actual bearing capacity of the bridge is obtained by field test. Through the comparative analysis of theory and practice, the health state of the bridge after five years of reinforced operation is judged. The damage to the overall stiffness and external prestressing of the bridge is also analyzed.FindingsThe results of deflection and strain show that the stiffness and strength of the secondary side span and the middle span decrease slightly, and the maximum reduction of bearing capacity is 4.5%. The static stiffness of the whole bridge decreases as a result of cracks, and the maximum decrease is 21%. In the past five years, the relaxation loss of the external prestressing of the bridge is 3.31–3.97%, which is the main reason for the decrease in bearing capacity.Originality/valueThrough the joint analysis of the bridge stiffness and the loss of external prestressing, the strengthening condition of the bridge after five years of operation is effectively analyzed. The strengthening effect of the external prestressed steel beam strengthening method is analyzed, which can provide a reference for similar bridge strengthening.

This study investigates six types of prediction methods for estimating extreme bridge traffic load effects, aiming to establish a correlation between prediction accuracy and data quality. Accurately determining the distribution functions of maximum values is crucial for assessing bridge safety under traffic loads. Methods including the Peaks Over Threshold, the block maxima approach, fitting to a Normal distribution, and the Rice formula based level crossing method, are investigated. Additionally, Bayesian Updating and Predictive Likelihood techniques, integrated with the block maxima approach, are explored. The performance of these methods is assessed using two distinct datasets. The first dataset is generated from a known distribution, allowing the estimated distribution parameters and extreme values derived from each method to be compared with the true values. The analysis is then extended to more realistic scenarios, where long-run simulations provide benchmark results for evaluating the accuracy of each method. Based on the findings, recommendations are provided for selecting the most suitable prediction method, considering factors such as sample size, time interval, and the type of load effect. This work offers practical insights for improving the reliability of extreme value prediction methods in bridge safety assessments.

In this paper, bridge live load testing was conducted to examine the performance of repairs on a section of a post-tensioned box girder bridge in Oklahoma City, Oklahoma. The live load test was performed with a single/group of truck(s) with known gross weight. The objective of this study was to characterize the behavior of the test bridge span by comparing the performance of a repair in situ as part of the bridge section’s structural response to that of a section known to be sound. To achieve the objective, the structural strain response was collected from several critical locations across the bridge girders. A comparative analysis of bridge behavior was carried out for the results from both the repaired and structurally sound areas to identify any deterioration and adverse changes. The structural strain response indicated an elastic behavior of the tested bridge span under three different load levels. Meanwhile, acoustic emission monitoring was implemented as a supplementary evaluation method. The acoustic emission intensity analysis also revealed an insignificant change in the effectiveness of the repair upon comparing results obtained from both locations. Although there were fluctuations in the b-value, it consistently remained above one across the different load testing scenarios, indicating no progressive damage and generally reflecting structural soundness, aligning with the absence of visible cracks in the monitored area.

Rock structural deterioration induced by coupled freeze–thaw and stress disturbance are a great concern for jointed rock mass during rock constructions in cold regions. Previous studies focused on fracture evolution of intact rock or flawed rock under freeze–thaw–static loads, but the coupling effect of freeze–thaw and cyclic loads on the pre-flawed hollow-cylinder rock is not well understood. This work investigated the influence of freeze–thaw on rock microstructure change and fatigue mechanical behaviors. Testing results show that rock strength, volumetric strain, and lifetime decrease with increasing F–T number. The stiffness degradation caused by cyclic loads is also impacted by the previous freeze–thaw damage. Additionally, the AE ring count and energy count decrease with the increase of F–T treatment. Large fracture signals are captured for rock that has smaller F–T cycles and at the stress-increasing moment. The AE b-value increases with F–T cycles, and it decreases rapidly near rock failure. Spectral analysis indicates that large-scaled cracking is prone to form for a sample having high F–T cycles. Moreover, 2D CT images reveal the differential crack network pattern at rock bridge segments and how it is affected by the previous freeze–thaw damage. The crack coalescence and hole collapse patterns and the associated structural deterioration of the rock bridge segment are obviously influenced by the F–T treatment.HighlightsFracture behaviors of pre-flawed hollow-cylinder granite under freeze-thaw-fatigue loads were analyzed.Cyclic freeze-thaw weathering influences rock microstructure and geomechanical properties.Acoustic emission parameters and spectral analysis reveals the impact of F-T on rock progressive failure.The crack coalescence and hole collapse patterns are obviously influenced by the F-T treatment.

The aim of the paper is an analysis of bridge loads changes in the 20 th century. The Polish bridge load standards issued in the 20 th century are considered here. The two static approaches are adopted on the basis of the model of the real composite of a steel and concrete bridge carrying-deck. The first of them, the traditional simplified Courbon method which was in use up to the 1970s, gives bending moment results. The other one is the analysis by the ABAQUS FEM. The dynamic response of the structure is performed for the set of velocities starting from 10 km/h to 90 km/h. Basing on the obtained results, it is concluded that the load increase is essential for bridge sustainability in all phases i.e. for design, maintenance and optional rebuilding. Having in mind that, in general, the indicative service life of a bridge is intended for 100 years approximately, i.e. for three generations, the prognosis of load changes is crucial. The bridge load effects increase over the past century is estimated at 60% to 85%, it being at least 30%.

Reinforced concrete arch bridges are susceptible to non-stationary degradation under combined environmental and load effects, rendering traditional reliability assessments based on stationary assumptions inadequate. To address this gap, this study first derived a reliability calculation method tailored for non-stationary degradation scenarios. Subsequently, an ISSA-Kriging surrogate model was proposed for the reliability evaluation of reinforced concrete arch bridges, with validation and analysis conducted using the Shuiluo River Bridge as an engineering case. Results indicate that the ISSA-Kriging model achieves high prediction accuracy: its sample response error is controlled within 4% in repeated random sampling tests, and its accuracy is approximately 60% higher than that of the standard Kriging model. The model reliably fits the time-varying reliability curve of the main arch ring, confirming its suitability for large-scale parametric analysis and engineering optimization. Compared with stationary degradation, non-stationary degradation accelerates the decay rate of the main arch ring’s reliability index by 20%–30%. After 50 years of service, the reliability reduction rates of the arch springing, arch crown, and mid-span (1/2 arch ring) under non-stationary degradation reach 90.8%, 97.8%, and 52.7%, respectively, leading to an obvious “unimodal” reliability distribution across the semi-structure of the main arch ring. Additionally, non-stationary load fluctuations exacerbate structural damage accumulation, emphasizing the need for targeted durability protection of key components. A limitation of this study is that the proposed non-stationary degradation model, while theoretically consistent with non-stationary deterioration laws and validated via numerical simulation, lacks direct calibration with long-term on-site monitoring data. Future research will focus on integrating structural health monitoring data to dynamically revise the model, narrowing the gap between numerical simulation and actual structural performance, and thereby enhancing the engineering practical value of non-stationary reliability assessment results. This study provides a robust technical tool for the non-stationary reliability assessment of reinforced concrete arch bridges and offers guidance for durability design and maintenance optimization.