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Recent studies have revealed that the frequency and magnitude of floods tend to increase due to climate change. Hence, excessive scouring due to flood events puts river bridges at greater risk of failure. This paper presents the initial findings of an experimental study to improve the understanding of the main characteristics of bridge pier scour under pressurized flow encountered during flooding. The experiments were carried out in four main groups according to two deck alignments with circular and oblong pier shapes. For each group of experiments, thirty-six tests were conducted under partially and fully pressurized flow conditions using four approach flow depths and three discharge values. The validity of the structured design approach for pier scour estimation implemented in the guidelines was investigated. The results showed that the bridge pier scour depths were up to 29.4% and 49.4% greater than the sum of the vertical contraction and local scour depths for 100 L/s for partially and fully pressurized flow conditions, respectively. However, as the discharge increased to 120 L/s, the bridge pier scour depth became 38.3% and 17.8% smaller than the sum of the vertical contraction and local scour depths for partially and fully pressurized flow, respectively. So, the structured design approach was determined to be safe for high discharge values. Furthermore, it was found that tests with a circular pier resulted in higher bridge pier scour depths than the sum of the vertical contraction and local scour depths up to 19.3% even for 120 L/s. Conversely, smaller bridge pier scour depths than the sum of the vertical contraction and local scour depths were observed up to 17.8% for tests with oblong piers. Thus, it can be concluded that the pier shape has a profound effect on scour holes and oblong piers cause smaller scour depths than circular piers in pressurized flow conditions. This study showed that the flow–pier–deck interaction significantly affects the depth and width of the scour hole, especially for small discharges and fully pressurized flow conditions. [ABSTRACT FROM AUTHOR]

Sediment scour numerical simulation plays a critical role in the design of water-resistant foundation engineering, and this paper addresses a significant gap in most related studies, which often overlook the transformation of sediment and struggle to identify the actual riverbed obscured by yielding bed and suspended load. To tackle this challenge, a comprehensive sediment model based on the meshless Smoothed Particle Hydrodynamics (SPH) method was developed. Firstly, to enhance computational efficiency and mitigate the high cost of Fluid-Solid Interaction (FSI) between water and sediments, cohesionless sediment grains were modelled as non-Newtonian fluids, with yield strength determined according to a combined strength criterion. Subsequently, sediment transformation and identification were determined based on sediment particle velocity and shear stress, with the seepage force driving yield sediment particle motion at the interface. The effectiveness of this comprehensive sediment model was validated through comparison with three scour experiments. The results show better agreement between the model and experimental data, with a root-mean-square error of less than 2.17% in scour morphology simulation and successful identification of the actual post-scouring bed surface in each case. However, the free surface simulation in this model still exhibits slight error, with a root-mean-square error of less than 8.35%. [ABSTRACT FROM AUTHOR]

Foundation scour is a critical phenomenon that may lead to the collapse of railway bridges. This issue is even more concerning in the current scenario where extreme weather events, such as floods, are becoming more severe and recurrent. Among different methodologies for assessing the structural integrity of railway bridges, vehicle-assisted monitoring has emerged as promising due to its low-cost and straightforward sensor installation compared to direct instrumentation of bridges. This paper provides a proof of concept of employing vehicle acceleration measurements from passing trains to detect the occurrence of bridge scour. To assess the effectiveness of accelerometer placement in data acquisition, vertical acceleration responses are collected from various positions throughout the vehicle and for different vehicles in the train, considering operational variabilities and measurement noise. A deep autoencoder model is used to process raw acceleration measurements collected during multiple train passages over a bridge affected by scour, where the scour damage is simulated as a local reduction in stiffness within a specific pier-foundation system. The difference between model-based and vehicle responses obtained from various observed events is the prediction error evaluated by the mean absolute error. The Kullback–Leibler divergence-based damage index is proposed to assess the number of vehicle-crossing events required to infer the damage. Finally, the approach's accuracy is evaluated using Receiver Operating Characteristic curves. The results demonstrate that the applied methodology is highly effective in detecting both 5% and 10% levels of scour damage for sensors placed on the front and rear bogies of the first and last vehicles, without any prior data preprocessing. [ABSTRACT FROM AUTHOR]

We conducted flume experiments to study the flow behavior around a debris accumulation at a two-pier bridge. An Acoustic Doppler Velocimetry was utilized to measure velocity in cases with and without debris. We examined the impact of this accumulation on the velocity field and bed shear stress to better understand the flow and sediment transport mechanisms near the debris buildup at the bridge. Debris clusters were found to cause strong downward flows behind the bridge piers and to create turbulent shear layers emanating from the debris base. These flow patterns caused an increase in bed shear stress behind the piers by up to 40%. Downstream of the bridge, the debris-induced bed shear stress increase persisted for a distance equivalent to four times the spacing between the piers. [ABSTRACT FROM AUTHOR]

Recent studies have revealed that the frequency and magnitude of floods tend to increase due to climate change. Hence, excessive scouring due to flood events puts river bridges at greater risk of failure. This paper presents the initial findings of an experimental study to improve the understanding of the main characteristics of bridge pier scour under pressurized flow encountered during flooding. The experiments were carried out in four main groups according to two deck alignments with circular and oblong pier shapes. For each group of experiments, thirty-six tests were conducted under partially and fully pressurized flow conditions using four approach flow depths and three discharge values. The validity of the structured design approach for pier scour estimation implemented in the guidelines was investigated. The results showed that the bridge pier scour depths were up to 29.4% and 49.4% greater than the sum of the vertical contraction and local scour depths for 100 L/s for partially and fully pressurized flow conditions, respectively. However, as the discharge increased to 120 L/s, the bridge pier scour depth became 38.3% and 17.8% smaller than the sum of the vertical contraction and local scour depths for partially and fully pressurized flow, respectively. So, the structured design approach was determined to be safe for high discharge values. Furthermore, it was found that tests with a circular pier resulted in higher bridge pier scour depths than the sum of the vertical contraction and local scour depths up to 19.3% even for 120 L/s. Conversely, smaller bridge pier scour depths than the sum of the vertical contraction and local scour depths were observed up to 17.8% for tests with oblong piers. Thus, it can be concluded that the pier shape has a profound effect on scour holes and oblong piers cause smaller scour depths than circular piers in pressurized flow conditions. This study showed that the flow–pier–deck interaction significantly affects the depth and width of the scour hole, especially for small discharges and fully pressurized flow conditions.

Scour is a significant contributing factor to bridge failures, and when a bridge fails, it totally or partially loses its serviceability, causing fatalities, delays in emergency transportation and evacuation efforts, and economic losses. The mechanism of scour in riverine environment is different from those in areas under wave action, that is, coastal, and lacustrine environments. A total of 38 experiments were conducted in the laboratory under wave-alone, current-alone, and waves–current combined conditions to investigate the flow pattern and geometry of scour holes around bridge piers. Under these conditions, different flow parameters were considered and the influence of these parameters on the scour hole geometry was observed. The results showed that the combination of wave and current produced scour depths larger than those of the wave-alone experiments but smaller than those created by the current. Particle image velocimetry was used to investigate the flow field around piers and observe changes in vortex characteristics due to the change in flow conditions. Finally, an attempt was made to relate the size and shape of vortices to the scour process. It was concluded that the strength of wake vortices, the relative direction of the flow and wave, and the distances of waves from the channel bottom influenced the scour geometry and the downstream deposition pattern. [ABSTRACT FROM AUTHOR]

Debris upstream of the bridge pier and through the flow variations, changes scour hole and river morphology. Dune forms downstream of the pier as a result of sediment movement in the pier scour phenomenon. The present study investigates the dune characteristics and geometrical parameters in experimental models. Experimental models are categorized into four cases including the pier, pier with buried debris, pier with free debris, and pier with free debris which was protected by bed sill at four various distances from the pier downstream face. It was concluded that debris submergence, densimetric particle Froude number, flow intensity, and bed sill affect dune geometrical parameters such as dune height (hd), dune crest position (xd), and dune length (ld). Results show dune height increases with debris accumulation up to almost 150% and its crest distance from the pier reduces up to approximately 100%. Also, in higher Fd, the dune height and its crest distance reduce with bed sill up to 50%, and in lower Fd, hd, and xd increase by up to 80% by using bed sill. Based on these effective parameters, three separate equations were proposed for hd, xd, and ld in pier scour with debris accumulation protected by bed sill. [ABSTRACT FROM AUTHOR]

Scour is the number one cause of bridge failure in many parts of the world. Considering the lack of reliability in existing empirical equations for scour depth estimation and the complexity and uncertainty of scour as a physical phenomenon, it is essential to develop more reliable solutions for scour risk assessment. This study introduces a novel AI approach for early forecast of scour based on real-time monitoring data obtained from sonar and stage sensors installed at bridge piers. Long-short Term Memory networks (LSTMs), a prominent Deep Learning algorithm successfully used for time-series forecasting in other fields, were developed and trained using river stage and bed elevation readings for more than 11 years, obtained from Alaska scour monitoring programme. The capability of the AI models in scour prediction is shown for three case-study bridges. Results show that LSTMs can capture the temporal and seasonal patterns of both flow and river bed variations around bridge piers, through cycles of scour and filling and can provide reasonable predictions of upcoming scour depth as early as seven days in advance. It is expected that the proposed solution can be implemented by transportation authorities for development of emerging AI-based early warning systems, enabling superior bridge scour management. [ABSTRACT FROM AUTHOR]

Scour is the prevailing cause of bridge failure worldwide, leading not only to traffic disruption, but also to social and economic losses and even to casualties. Many vibration-based monitoring techniques have been proposed for identifying the scour location and extent, based on the evaluation of the changes of the bridge modal properties due to scour. This study describes the experimental and numerical research carried out to investigate the effects of scour on the dynamic properties of structures with shallow foundations. Although these are the most vulnerable ones, they have received less attention compared to structures founded on pile foundations. To fill some existing knowledge gaps, field experiments were carried out on EuroProteas, a structural prototype with shallow foundation that was subjected to increasing levels of scour. The changes of the dynamic properties of the system are evaluated by postprocessing the ambient vibration recordings and by developing various models of the soil–foundation–structural system with different descriptions of the soil–structure interaction problem. The study results shed light on the effects of scour on systems with shallow foundations and on the accuracy of alternative modelling approaches. They are presented here to inform the development and validation of vibration-based techniques and modelling strategies for bridge scour identification. [ABSTRACT FROM AUTHOR]

Scouring of pile group foundations is a common phenomenon for cross-river bridges and can produce significant damage in earthquake-prone regions. This study experimentally investigated the seismic failure mechanism and postearthquake vertical load-carrying capacity of scoured pile group foundations. Three identical 2 × 3 reinforced concrete (RC) pile group specimens were embedded in homogeneous medium density sand with an overall scour depth equal to five times the diameter of a single pile, and then were subjected to lateral cyclic loads applied to the pile cap in order to produce a predetermined damage state in the piles. Pushover in the vertical-downward direction (pushdown) was finally applied on these damaged specimens exhibiting a permanent lateral displacement to evaluate their residual load-carrying capacities. Experimental results show that the leading pile was more prone to seismic damage, as both the first aboveground and first belowground plastic hinges originally occurred on it. The embedded depth of potential plastic hinges in leading, middle, and trailing piles gradually increased. In addition, the extension of pile damage had a significant influence on the residual vertical load-carrying capacity and the corresponding vertical failure mode of the pile group. Reductions of 10.4%, 47.5%, and 73.8% in the vertical load-carrying capacity of these scoured pile group specimens were recorded when they previously suffered a displacement ductility of 1.75, 3.5, and 5.0, respectively. Based on the experimental results, a linear degradation formula on the normalized postearthquake vertical load-carrying capacity of pile groups with respect to the displacement ductility was developed. The experimental results presented in this paper could be used to validate the ductility capacity and residual vertical load-carrying capacity of pile groups numerically evaluated by using three-dimensional nonlinear finite-element models. This research represents also a first step toward the development of a rapid postearthquake assessment approach for bridges with pile group foundations.

Copyright of Journal of Southeast University / Dongnan Daxue Xuebao is the property of Journal of Southeast University Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Local scour around bridge piers and abutments is one of the most significant causes of bridge failure. Despite a plethora of studies on scour around individual bridge piers or abutments, few studies have focused on the joint impact of a pier and an abutment in proximity to one another on scour. This study conducted laboratory experiments and flow analyses to examine the interaction of piers and abutments and their effect on clear-water scour. The experiments were conducted in a rectangular laboratory flume. They included 18 main tests (with a combination of different types of piers and abutments) and five control tests (with individual piers or abutments). Three pier types (a rectangular pier with a rounded edge, a group of three cylindrical piers, and a single cylindrical pier) and two abutment types (a wing–wall abutment and a semi-circular abutment) were used. An acoustic Doppler velocimeter was used to measure the three-dimensional flow velocity for analyses of streamline, velocity magnitude, vertical velocity, and bed shear stress. The results showed that the velocity near the pier and abutment increased by up to 80%. The maximum scour depth around the abutment increased by up to 19%. In contrast, the maximum scour depth around the pier increased significantly by up to l71%. The presence of the pier in the vicinity of the abutment led to an increase in the scour hole volume by up to 87% relative to the case with a solitary abutment. Empirical equations were also derived to accurately estimate the maximum scour depth at the pier adjacent to the abutment.

Scour can increase the earthquake-induced damage in pile group foundations. Quantifying the parameter sensitivity of the seismic performance for scoured pile group foundations is essential for the optimal design and retrofit of bridges located in seismic-prone regions. Such quantification requires numerical models that are computationally efficient and accurate in describing the mechanical behavior associated with the complex soil–foundation–structure interaction of these systems. This study proposes an efficient finite-element model (FEM) of pile groups based on a beam on the nonlinear Winkler foundation approach. This FEM uses asymmetric p-multipliers to describe the different soil resistance exerted on leading and trailing piles when applying cyclic lateral loads. The proposed FEM is validated by comparing the numerical response with the experimental measurements taken from a quasi-static test available in the literature and is used to perform an extensive parametric sensitivity analysis to quantify the response sensitivity to 11 structural and soil parameters. Tornado diagrams are employed to identify an importance ranking of these parameters on the seismic performance of scoured pile groups. The obtained results indicate that the proposed FEM is able to capture both the global and local structural responses of pile group foundations. The parametric sensitivity analysis shows that pile group foundations have considerable ductility capacity. Pile diameter and axial load ratio of piles are the most important parameters for the seismic performance of pile groups. Increasing the pile diameter is the most efficient approach to improve the seismic performance of a pile group when considering scour effects. The seismic performance of a scoured pile group deteriorates with increasing piles' axial load ratio. For a deep pile group foundation, seismic performance is very little sensitive to pile length and relative density of sand. Based on the results of the parametric analysis, recommendations are proposed for the seismic design of pile group foundations with scour effects. [ABSTRACT FROM AUTHOR]

High-frequency velocimeters used for flow measurements during laboratory experiments allow the user to select the range for several operation parameters to set up the instrument for optimal velocity measurement. The discrepancies between velocity measurements collected with different instrument configurations can be significant, depending on the flume bed configuration and boundary conditions. The aim of this paper is to quantify the differences in flow velocity profiles measured with Acoustic Doppler Velocimeter Profilers (ADVPs) configured using a combination of profiling parameters: Ping Algorithm (PA), Transmit Pulse Size (TPS), and Cell Size (CS). Whereas in Part I of this research, the goal was to identify the optimal probe configuration for downstream measurement of the complex hydraulic structure (pier protected with riprap) based on a match of the flow rate with measurements from other instruments, in this paper, effect of distinct probe configuration on velocity profile and turbulent kinetic energy (TKE) is demonstrated. Differences between ADVPs' configurations were analyzed through sensitivity analysis with the intention to calculate and compare any discrepancies in the velocity measurements for all the three measured velocity components: streamwise u, spanwise v and vertical w collected on two characteristic flume cross-sections. The results show that each parameter change has a significant effect on the measured values of each velocity component when compared to the Target Configuration (TC). The largest root-mean-square-error (RMSE) is observed when TPS is changed, followed by CS and PA. Absolute RMSE calculated for TPS change from 4 mm to 1 mm is, on average, 6.30 cm/s, 0.90 cm/s, and 0.82 cm/s for velocity components u, v and w, respectively. Absolute RMSE calculated for CS change from 1 mm to 4 mm is, on average, 4.49 cm/s, 0.88 cm/s, and 0.71 cm/s for velocity components u, v and w, respectively. Absolute RMSE calculated for PA change from Adaptive to Max interval is, on average, 4.04 cm/s, 0.63 cm/s, and 0.68 cm/s for velocity components u, v and w, respectively. For a change in all parameters, RMSE is greater for the cross-section downstream of the pier than for the approach cross-section: on average, 90%, 57% and 54% for a change in the PA, TPS, and CS, respectively. [ABSTRACT FROM AUTHOR]

Scour is an important cause of bridge failures. This article investigates the impact of climate change on bridge-pier scour in all 246 Swedish catchment areas. Although a few previous studies assessed the impact of climate change on bridge-pier scour in other countries, none of those studies identified the locations within a certain country where climate change is projected to have the highest impacts on bridge scour. A novel national-level method, based on possibility theory, is proposed herein for addressing this gap. The proposed method provides answers to the following questions: For which catchment areas is the projected increase in pier-scour depth highest or lowest? What is the percentage of catchment areas where climate change is projected to have either a positive or negative impact on scour risk in all scenarios? Which climate change scenarios cause the highest or lowest increase in equilibrium scour depth? Although these questions are addressed particularly for Sweden, the proposed method is generally applicable for any other location. The catchment area Riebnesströmmen (located in the northernmost county in Sweden) was identified to have the highest increase in the equilibrium scour depth in all considered reference periods (up to ∼25% increase), whereas the catchment area with the lowest increase varied depending on the considered reference period. The answers to the second question depended on the reference period and ranged from ∼5% to ∼10% and ∼8% to ∼14% for positive and negative impacts on scour risk, respectively. Interestingly, for the third question, it was found that higher-emission scenarios are not always more critical than lower-emission ones. These findings demonstrate the importance of performing national-level analyses of climate change impacts on infrastructure considering the different scenarios. The proposed method enables an efficient allocation of resources for adapting bridges to the increased scour risk due to climate change. Additionally, it can serve as a useful tool for quickly estimating the impact of climate change on bridge-pier scour for a certain location. [ABSTRACT FROM AUTHOR]

Throughout the lifespan of a bridge, morphological changes in the riverbed affect the variable action-imposed loads on the structure. This emphasizes the need for accurate and reliable data that can be used in model-based projections targeted for the identification of risk associated with bridge failure induced by scour. The aim of this paper is to provide an analysis of scour depth estimation on large sand-bed rivers under the clear water regime, detect the most influential (i.e., explanatory) variables, and examine the relationship between them and scour depth as a response variable. A dataset used for the analysis was obtained from the United States Geological Survey's extensive field database of local scour at bridge piers, i.e., the Pier-Scour Database (PSDB-2014). The original database was filtered to exclude the data that did not reflect large sand-bed rivers, and several influential variables were omitted by using the principal component analysis. This reduction process resulted in 10 influential variables that were used in multiple non-linear regression scour modeling (MNLR). Two MNLR models (i.e., non-dimensional and dimensional models) were prepared for scour estimation; however, the dimensional model slightly overperformed the other one. According to the Pearson correlation coefficients (r), the most influential variables for estimating scour depth were as follows: Effective pier width (r = 0.625), flow depth (r = 0.492), and critical and local velocity (r = 0.474 and r = 0.436), respectively. In the compounded hydraulic-sediment category, critical velocity had the greatest impact (i.e., the highest correlation coefficient) on scour depth in comparison to densimetric Froude and critical Froude numbers that were characterized by correlation coefficients of r = 0.427 and r = 0.323, respectively. The remaining four variables (local and critical bed shear stress, Froude number, and particle Reynolds number) exhibited a very weak correlation with scour depth, with r < 0.3. [ABSTRACT FROM AUTHOR]

Scour is the leading cause of bridge collapse beneath any bridge pier located within the waterway. A numerical-based hydraulic model named the Hydrologic Engineering Centre River Analysis System and a mathematical model of the Florida Department of Transport were implemented to investigate their performance and accuracy in estimating the maximum scour depth beneath bridge piers where large and small-scale physical prototypes are used as a benchmark. The main findings are that a hydraulic model is an effective tool when employing the Colorado State University equation, which compares well with physical prototypes irrespective of the variation in piers' size and shape. Also, it has achieved more consistent results than the Froehlich and the Florida Department of Transport methodologies. [ABSTRACT FROM AUTHOR]

To design the foundation system of waterway bridges, Load and Resistance Factor Design guidelines suggest use of deterministic scour depth prediction models. Understanding the inherent bias of deterministic scour depth prediction models will advance the development of reliability index-based foundation design regime. Four bridge scour depth prediction models were assessed in terms of two statistical parameters, termed herein mean absolute percentage error (MAPE), and conservatism, percentage of cases the predicted scour depth exceeded the measured scour depth. Live-bed laboratory and field scour depth databases were used in analyses to quantify model scatter by comparatively assessing the computed scour depth versus measured data. For live-bed laboratory data, values of MAPE ranged from 23.5% to 59.8%, whereas conservatism ranged from 28.4% to 97.8%. For live-bed field data, conservatism varied from 93.3% to 95.1%, while MAPE ranged from 205.6% to 319%. Statistical models were applied to ascertain the biasness of the four deterministic models. Accuracy and conservatism of a given model were consequently adjusted through proposed modification factors. The proposed approach allows for the selection of a suitable modification factor to satisfy a target probability of deceedance or a target conservatism. [ABSTRACT FROM AUTHOR]

The scour around the bridge piers has been estimated using conventional empirical formulae; however, these formulae are unable to predict the scour depth precisely. The present study is conducted in two parts (a) experimental investigation for evaluating the behaviour of local scour around twin piers positioned in the transverse direction of flow and (b) an empirical equation to estimating scour depth is proposed utilising new evolutionary artificial intelligence technique gene expression programming (GEP). Experimental results for the present study demonstrate the influence of the rate of flow and clear spacing between the piers on the scour depth. Additionally the results of the soft computing technique GEP during testing and training of proposed modelling, fitness function root mean square error is observed as 0.00133 and 0.00113, with the coefficient of determination as 0.950 and 0.955, respectively. Furthermore, in order to find out the role of each variable for scour depth sensitivity, analysis has been conducted. The findings of the sensitivity analysis show that the pier spacing and rate of flow play the most significant role in scour depth estimation. Results of this study demonstrate a good agreement with the proposed GEP model and conclude that it is a better approach for forecasting scour depth. HIGHLIGHTS Experimental investigation to assess the influence of flow rate and centre-to-centre spacing on local scour around the piers.; GEP technique is used for estimating scour depth.; Sensitivity analysis for assessing the influence of various parameters.; The prediction capability of GEP is compared with the existing semi-empirical equations.;

Foundation scour is a widespread reason for the collapse of bridges worldwide. However, assessing bridges is a complex task, which requires a comprehensive understanding of the phenomenon. This literature review first presents recent scour detection techniques and approaches. Direct and indirect monitoring and machine learning algorithm-based studies are investigated in detail in the following sections. The approaches, models, characteristics of data, and other input properties are outlined. The outcomes are given with their advantages and limitations. Finally, assessments are provided at the synthesis of the research. [ABSTRACT FROM AUTHOR]

Scouring at bridge piers is a crucial issue that risks bridge collapses, causing economic losses and endangering public safety. Classic models struggle to accurately estimate equilibrium scour depth (d se) due to the complex scouring mechanism. This study combines Bayesian optimization (BO) with support vector machine (SVM) and extreme gradient boosting (XGBoost) to improve d se estimates. These models predict d se around round-nosed, square, and sharp-nosed bridge piers using field and laboratory data. The results demonstrate that the BO algorithm can effectively optimize the hyperparameters of SVM and XGBoost and ameliorate their d se estimates. For the square, sharp-nosed, and round-nosed piers, BO–XGBoost achieves the lowest mean absolute error (MAE) of 0.37 m, 0.35 m, and 0.36 m, the lowest root mean square error (RMSE) of 0.52 m, 0.60 m, and 0.56 m, and the highest coefficient of determination (R2) of 0.85, 0.80, and 0.84, respectively. Accurate estimation of d se is essential to balance safety and affordability of the bridge designs. Underestimating d se can lead to bridge failure, posing significant safety risks. Conversely, overestimating d se can result in unnecessary construction expenses. Finally, the impact of independent variables on d se estimates is analyzed using Shapley additive explanations (SHAP). • Traditional models struggle with accurate equilibrium scour depth (d se) predictions due to complex scouring mechanisms. • Bayesian optimization combined with SVM and XGBoost improves d se estimation accuracy. • Models predict d se for round, square, and sharp-nosed piers using field and lab data. • BO–XGBoost demonstrated the most accurate results with low MAE and RMSE and high R2 for various pier shapes. • SHAP analysis reveals the impact of different variables on d se estimates. [ABSTRACT FROM AUTHOR]

• Proposes a risk-informed framework for prioritizing scour-susceptible bridges. • Adequate consideration needs to be given for the geographic, structural, hydrogeological, and flood-related factors that contribute to scour formation. • Practical application through a GIS-based approach is presented through a case study on the UK railway network. Scour-induced failures of bridges pose a global challenge, leading to significant economic and service losses. Compounded by infrequent inspections and inadequate consideration of hydro-geological factors in current scour risk assessments, this issue is particularly pressing in the context of climate change and associated hazards. Addressing the imperative for enhanced infrastructure resilience, this study introduces a framework for scour risk management. Utilizing Geographic Information Systems (GIS) datasets and applying the Analytic Hierarchy Process (AHP) to assess various weighted factors affecting scour risk, we have systematically mapped information layers encompassing structural, riverine, geological, and flood risk to conduct a strategic scour susceptibility assessment. The proposed approach is applied to the railway network in southeast England, identifying scour-susceptible bridges that can be prioritized for detailed inspections. Compared to the existing scores, the proposed scour risk scores for approximately 30 railway bridges in the region were adjusted, with 22 transitioning from medium to high priority. Our proposed methodology, exemplified by this case study, offers asset managers deeper insights into the determinants of scour susceptibility of bridges and facilitates informed decision-making for prioritizing scour-mitigation measures across the network. [ABSTRACT FROM AUTHOR]

Experiments were performed for local scour at a complex pier with two inclined, rectangular columns footed on a group of circular piles with a pile cap. The research fills a gap in existing literature, where studies for complex piers have considered a single, vertical column. The laboratory campaign involved the variation of the pile diameter and arrangement, and of the cap thickness and elevation above the non-scoured bed. The results of carefully conducted scour runs revealed the cap elevation as a most influential parameter. In cases of buried and partially buried pile cap, in fact, the cap acted as a scour countermeasure. For high cap elevation, the supporting piles were also exposed to the flow and their size influenced the resulting scour depth values as it directly impacted on the pier frontal area. The measured scour depth was compared to the values predicted by several literature methods for complex piers with a vertical column, supporting the possibility to extend their use to the geometry investigated in the present study. [ABSTRACT FROM AUTHOR]

Copyright of Vatten is the property of Foreningen Vatten and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Flow mapping around bridge piers is crucial in estimating scour development potential under different flow conditions. The reliable measurement of turbulence and the estimation of Reynolds stress can be achieved on scaled models under controlled laboratory experiments using high-frequency Acoustic Doppler Velocimeter Profilers (ADVP) for flow measurement. The aim of this paper was to obtain operation parameters for an array of Vectrino Profilers for turbulent flow field measurement to reliably measure the flow field around bridge piers. Laboratory experiments were conducted on a scaled river model set up in an open channel hydraulic flume. Flow field data were measured on three characteristic profiles, each containing five measurement points collected by ADVPs configured as an array of two instruments. The determination of the operation parameters was done as a two-step process—calibration through the flume's pump flow rate and verification with Acoustic Doppler Current Profiler RioGrande field data. Based on the results, the following setup for ADVPs' operation parameters can be used to obtain reliable flow data in the scour hole next to the bridge pier: adaptive Ping Algorithm, Transmit Pulse Size of 4 mm and Cell Size of 1 mm. [ABSTRACT FROM AUTHOR]

A bridge scour identification method was developed based on a time-frequency analysis that was combined with trend change detection. The basic concept behind this method is to probabilistically consider the interference-induced random variations in the natural frequencies to reveal their scour-induced change trends. First, the natural frequencies were instantaneously analyzed based on the bridge structural health monitoring (BSHM) data by time-frequency analysis. The probability distribution of the frequencies is obtained by kernel density estimation (KDE) and normalized by the probability integral transform theory. Then, based on the normal fluctuation in the frequencies that were defined by the control limits, an anomaly diagnosis for the frequencies is conducted using the control chart method. Continuously diagnosed anomalies are further regarded as a detected trend change in the frequencies, which is the key indicator to warn of scour in terms of the probability (P). Finally, the Jintang Bay Bridge, Zhoushan, Zhejiang Province, China, which is a 1,210-m-long cable-stayed bridge, was selected as a case study to comprehensively illustrate the application of this method using numerical simulations. The long-term BSHM field data from the Anqing Yangtze River Bridge, Anqing, Anhui Province, China, which is a 1,038.5-m-long cable-stayed bridge, were used as another case study to effectively prove the validity of this method in practice. These applications showed that the proposed bridge scour identification method that was based on time-frequency analysis and probabilistic trend change detection is effective. The developed methodology does not require any underwater devices and operations and could be conveniently integrated into a routine BSHM system. [ABSTRACT FROM AUTHOR]

Bridges are indispensable structures vital to the operation of road and rail transportation networks. Crossing rivers and artificial waterways, however, presents a risk to their foundations due to scour actions. Scour is the number one cause for bridge failures and may occur beneath any bridge, large or small, with supports located within the waterway. This paper provides a summary of present scour detection and measurement equipment and associated assessment methodologies. In this regard, particular emphasis is placed on structural health monitoring better to evaluate the presence and influence of potential scour. A Sensitivity Analysis on a newly introduced monitoring system is also assumed. Furthermore, much research has been undertaken to create a technology that can instantly identify and detect bridge scour, improving survey reliability through prior inspection and prompt intervention. This research will explore and evaluate bridge scour detection methods employed and suggest a possible path for developing the detection system to identify scour depth effectively and efficiently. Finally, our key aim is to minimize human effort in identifying and bridge scour by using a quick, easy-to-use, cost-effective process, resulting in fewer injuries and economic savings.

High-frequency velocimeters used for flow measurements during laboratory experiments allow the user to select the range for several operation parameters to set up the instrument for optimal velocity measurement. The discrepancies between velocity measurements collected with different instrument configurations can be significant, depending on the flume bed configuration and boundary conditions. The aim of this paper is to quantify the differences in flow velocity profiles measured with Acoustic Doppler Velocimeter Profilers (ADVPs) configured using a combination of profiling parameters: Ping Algorithm (PA), Transmit Pulse Size (TPS), and Cell Size (CS). Whereas in Part I of this research, the goal was to identify the optimal probe configuration for downstream measurement of the complex hydraulic structure (pier protected with riprap) based on a match of the flow rate with measurements from other instruments, in this paper, effect of distinct probe configuration on velocity profile and turbulent kinetic energy (TKE) is demonstrated. Differences between ADVPs’ configurations were analyzed through sensitivity analysis with the intention to calculate and compare any discrepancies in the velocity measurements for all the three measured velocity components: streamwise u, spanwise v and vertical w collected on two characteristic flume cross-sections. The results show that each parameter change has a significant effect on the measured values of each velocity component when compared to the Target Configuration (TC). The largest root-mean-square-error (RMSE) is observed when TPS is changed, followed by CS and PA. Absolute RMSE calculated for TPS change from 4 mm to 1 mm is, on average, 6.30 cm/s, 0.90 cm/s, and 0.82 cm/s for velocity components u, v and w, respectively. Absolute RMSE calculated for CS change from 1 mm to 4 mm is, on average, 4.49 cm/s, 0.88 cm/s, and 0.71 cm/s for velocity components u, v and w, respectively. Absolute RMSE calculated for PA change from Adaptive to Max interval is, on average, 4.04 cm/s, 0.63 cm/s, and 0.68 cm/s for velocity components u, v and w, respectively. For a change in all parameters, RMSE is greater for the cross-section downstream of the pier than for the approach cross-section: on average, 90%, 57% and 54% for a change in the PA, TPS, and CS, respectively.

Morphodynamic changes in the riverbed may be accelerated by the climate change-induced effects, mostly through the increase of the frequency of extreme climatic events such as floods. This can lead to scouring of the riverbed around the bridge substructure and consequently reduces its overall stability. In order to better understand hydromorphological processes at the local scale, the influence of floods on bridge scour requires a detailed analysis of several interacting flood hydrograph characteristics. This paper presents a multivariate analysis of the annual maximum (AM) flood discharge data at four gauging stations on the Drava and Sava Rivers in Croatia (Europe). As part of the hydrograph analysis, multiple baseflow separation methods were tested. Flood volumes and durations were derived after extracting the baseflow from measured discharge data. Suitable marginal distribution functions were fitted to the peak discharge (Q), flood volume (V) and duration (D) data. Bivariate copula analyses were conducted for the next pairs: peak discharge and volume (Q–V), hydrograph volume and duration (V–D) and peak discharge and hydrograph duration (Q–D). The results of the bivariate copula analyses were used to derive joint return periods for different flood variable combinations, which may serve as a preliminary analysis for the pilot bridges of the R3PEAT project where the aim is to investigate the influences on the riverbed erosion around bridges with installed scour countermeasures. Hence, a design hydrograph was derived that could be used as input data in the hydraulic model for the investigation of the bridge scour dynamics within the project and a preliminary methodology is proposed to be applied. The results indicate that bivariate frequency analysis can be very sensitive to the selected baseflow separation methodology. Therefore, future studies should test multiple baseflow separation methods and visually inspect the performance. [ABSTRACT FROM AUTHOR]

Evaluation of scour depth is essential but challenging for the design and surveillance of bridges. The current engineering practice is primarily based on empirical equations. However, without considering geomechanics concepts, these methods are not always reliable, especially when utilised under different geological conditions. This paper introduces a new approach based on the geomechanical equilibrium concept, i.e. erosive force versus the erosion resistance. This analysis procedure incorporates the geomechanics concepts, and it can be solved by coupling computational fluid dynamics and soil particles. Based on numerical investigations considering soil particles, cases of scour prediction considering soil layer distributions have been carried out. With this concept, scour processes in layer-distributed soils and under different flood consequences have been analysed. It can be applied to investigate the scour process considering layered soils with different erosion resistance distributions and various hydraulic conditions. It is found that the proposed model can provide reliable results and explain a few scour phenomena, which are difficult to explain with traditional models. [ABSTRACT FROM AUTHOR]

For bridges with surface foundations, scour is one of the main reasons for bridge failures. In regard to structural health monitoring, vibration-based scour detection techniques have received increasing attention over the past two decades. Scour occurs below the water surface in rivers or sea, leading to difficulty in equipment installation and maintenance. Recently, the concept of "drive-by" SHM using the indirect measurement of passing vehicle responses has been developed rapidly due to its convenience and low cost. This paper proposes a method to detect scour using the vehicle responses under an operational vehicle speed. The wavelet transform was applied to vehicle accelerations to obtain the wavelet energy. It was found that the wavelet energy increases with the increase in the scour damage level. However, the wavelet energy may also be affected by the on-site operating environments, such as sensor noise and other variabilities, which interferes with the identification of scour in practice. Hence, in this work, a statistical-wavelet-based approach was presented to effectively detect the presence of scour and even its location. The feasibility of the proposed approach is verified in both numerical simulation and lab experiments. The results show that the proposed method has a good potential to detect scour using indirect measurements. [ABSTRACT FROM AUTHOR]

There are many historical bridges around the world whose crucial information regarding their foundations is unknown. Such information is essential for an accurate safety assessment regarding scour hazard. Current methods for identification of bridge foundation characteristics are typically expensive, potentially disruptive, and limited in their applications. Thus, the numerical feasibility study described in this paper assessed whether a nondestructive geophysical technique such as electrical resistivity tomography (ERT) could be used for this purpose. Synthetic scenarios were created accounting for different combinations of material resistivity. Two standard measurement sequences (dipole–dipole and Schlumberger) and an optimized one ("Compare R" method) were tested. Results showed that the depth of the bridge foundation was roughly well represented in all cases. However, the optimized sequence revealed slightly better results. Although this small improvement observed did not significantly affect the results of the simplified scenarios assessed by this study, it could be decisive for more complex scenarios. These findings demonstrated that ERT can be used to identify the depth of bridge foundations in an inexpensive, rapid, and nonintrusive way, allowing for more accurate assessment of bridge safety and scour risk ratings. [ABSTRACT FROM AUTHOR]

Due to Typhoon Hagibis (Typhoon No. 19) in October 2019, also known as the Reiwa 1 East Japan Typhoon, many parts of the Chikuma River’s levee in Nagano Prefecture were damaged. There were instances of levee collapse due to overtopping, and an electric railway bridge also collapsed when an eroded revetment broke. In the present study, these disasters were investigated.The investigation considered both the geology - geomechanics and the hydraulics of the levee collapse due to overtopping. The results suggest that the most significant factor in the collapse of the levee was structural weakness. There were cases in which the tenacity of a levee was improved by taking simple measures against seepage. It was found that the bridge abutments washed away mainly because the river levee became a water-colliding front due to changes in the water route following the erosion of a sandbar in the process of river level decline after the peak.

Throughout the lifespan of a bridge, morphological changes in the riverbed affect the variable action-imposed loads on the structure. This emphasizes the need for accurate and reliable data that can be used in model-based projections targeted for the identification of risk associated with bridge failure induced by scour. The aim of this paper is to provide an analysis of scour depth estimation on large sand-bed rivers under the clear water regime, detect the most influential (i.e., explanatory) variables, and examine the relationship between them and scour depth as a response variable. A dataset used for the analysis was obtained from the United States Geological Survey’s extensive field database of local scour at bridge piers, i.e., the Pier-Scour Database (PSDB-2014). The original database was filtered to exclude the data that did not reflect large sand-bed rivers, and several influential variables were omitted by using the principal component analysis. This reduction process resulted in 10 influential variables that were used in multiple non-linear regression scour modeling (MNLR). Two MNLR models (i.e., non-dimensional and dimensional models) were prepared for scour estimation; however, the dimensional model slightly overperformed the other one. According to the Pearson correlation coefficients (r), the most influential variables for estimating scour depth were as follows: Effective pier width (r = 0.625), flow depth (r = 0.492), and critical and local velocity (r = 0.474 and r = 0.436), respectively. In the compounded hydraulic-sediment category, critical velocity had the greatest impact (i.e., the highest correlation coefficient) on scour depth in comparison to densimetric Froude and critical Froude numbers that were characterized by correlation coefficients of r = 0.427 and r = 0.323, respectively. The remaining four variables (local and critical bed shear stress, Froude number, and particle Reynolds number) exhibited a very weak correlation with scour depth, with r < 0.3.

In near-field remote sensing, noncontact methods (radars) that measure stage and surface water velocity have the potential to supplement traditional bridge scour monitoring tools because they are safer to access and are less likely to be damaged compared with in-stream sensors. The objective of this study was to evaluate the use of radars for monitoring the hydraulic conditions that contribute to bridge–pier scour in gravel-bed channels. Measurements collected with a radar were also leveraged along with minimal field measurements to evaluate whether time-integrated stream power per unit area (Ω) was correlated with observed scour depth at a scour-critical bridge in Colorado. The results of this study showed that (1) there was close agreement between radar-based and U.S. Geological Survey streamgage-based measurements of stage and discharge, indicating that radars may be viable tools for monitoring flow conditions that lead to bridge pier scour; (2) Ω and pier scour depth were correlated, indicating that radar-derived Ω measurements may be used to estimate scour depth in real time and predict scour depth based on the measured trajectory of Ω. The approach presented in this study is intended to supplement, rather than replace, existing high-fidelity scour monitoring techniques and provide data quickly in information-poor areas. [ABSTRACT FROM AUTHOR]

River bridge piers may collapse due to the local scour around their foundations. It is known that local scour is an effect of the three-dimensional flow field that develops near the pier and that the geometric complexity of a non-cylindrical pier may, correspondingly, increase the complexity of the process. It is also known that various devices may be used as scour countermeasures. This manuscript explores the use of a bed sill as a countermeasure for local scour at a complex bridge pier compound of an array of piles, a pile cap, and two inclined columns with the rectangular sections above the cap. This pier geometry, never studied before in combination with a scour countermeasure, was stimulated by an existing bridge. Different sill placements were tested (at the upstream or downstream edges of the pier, or in an intermediate position) for various values of the pile diameter and number, cap thickness and cap elevation. The results of a wide experimental campaign consistently showed that the most effective placement of the transverse sill was at the upstream edge of the pier, for which scour reductions of up to 30–40% could be obtained for the long-term scour depth. The countermeasure performance decreased to about 10% when the sill was placed at the downstream edge of the pier. Furthermore, the installation of a transverse sill upstream of the pier also changed the shape of the scour hole because the pier was then located in an area prone to sill scour; however, for the present experiments, the combination of the effects was beneficial in terms of the resulting scour depth. Although the investigation of a single hydro-dynamic condition prevents the experimental findings from being generalized, the promising results stimulate further consideration of a transverse sill as a countermeasure for local scour at a complex pier. [ABSTRACT FROM AUTHOR]

Foundation scour is a widespread reason for the collapse of bridges worldwide. However, assessing bridges is a complex task, which requires a comprehensive understanding of the phenomenon. This literature review first presents recent scour detection techniques and approaches. Direct and indirect monitoring and machine learning algorithm-based studies are investigated in detail in the following sections. The approaches, models, characteristics of data, and other input properties are outlined. The outcomes are given with their advantages and limitations. Finally, assessments are provided at the synthesis of the research.

Prediction of maximum scour depth at complex bridge piers is frequently decisive for the safe design of bridges. Some methods are available for this purpose but, due to the discrepancies of their predictions, such methods deserve further validation on the basis of new and independent data sets. For this purpose, clear-water experiments were performed by systematically varying the pile-cap elevation of a particular pier shape. Equilibrium scour depths were reached and measured and the comparison of predictions with measurements was established. The method of Sheppard and Renna, published in 2005, was found to predict with the highest accuracy the attained results for the tested complex pier. However, it should be stressed that this method slightly underestimates scour when the pile cap is out of the water or partly imbibed in the flow. It also under-predicts the scour depth when the pile cap is deeply buried in the bed. [ABSTRACT FROM AUTHOR]

Floods, bridge scour, and flood-associated loads have caused over sixty percent of bridge failures in the U.S. Current practices for the vulnerability assessment of instream bridges under the effect of such flood largely rely on qualitative methods, such as visual inspection, without considering uncertainties associated with structural behaviors and flood loads. Recently, numerical methods have been investigated to quantitatively consider such uncertainty effects by adapting fragility analysis concept that has been well established in the earthquake engineering area. However, river hydraulics, geotechnical uncertainties of foundation, variable scour-depth effects, and their significance in structural fragility of bridges have rarely been systematically investigated. This study proposes a comprehensive fragility analysis framework that can effectively incorporate both flow hydraulics and geotechnical uncertainties, in addition to commonly considered components in flood-fragility analysis of bridges. The significance of flow hydraulics and geotechnical uncertainties has been demonstrated through a real-bridge case study. Conventional fragility curves with maximum scour depth may not represent actual vulnerability during floods, as the scour may not reach to the maximum in many cases. Therefore, fragility surface with two intensity measures, i.e. flow discharges and scour depths, is introduced for real-time vulnerability assessment during floods in this study. [ABSTRACT FROM AUTHOR]

Previous research has shown that local scour at bridge piers is severely increased by the accumulation of woody debris around piers. However, due to the unavailability of accurate information regarding the characteristics of formed debris jams, the shape and dimensions of accumulations tested in previous laboratory experiments have had to be assumed. This article provides an assessment of debris-induced scour based on recently available knowledge about the relation between the potential dimensions of debris accumulations, the characteristics of flow, and debris elements. Clear-water scour experiments (with and without debris accumulation) were conducted using debris models with shape and size that correspond to the particular flow characteristics of each experiment. The results showed that scour depths obtained with flow-dependent debris accumulations were larger than without accumulations by a factor ranging from 1.18–2.19. The analysis of the scour depths affected by the accumulations suggested similar characteristics as well as dependence on the flow intensity, blockage area ratio, and depth ratio. [ABSTRACT FROM AUTHOR]

Flow mapping around bridge piers is crucial in estimating scour development potential under different flow conditions. The reliable measurement of turbulence and the estimation of Reynolds stress can be achieved on scaled models under controlled laboratory experiments using high-frequency Acoustic Doppler Velocimeter Profilers (ADVP) for flow measurement. The aim of this paper was to obtain operation parameters for an array of Vectrino Profilers for turbulent flow field measurement to reliably measure the flow field around bridge piers. Laboratory experiments were conducted on a scaled river model set up in an open channel hydraulic flume. Flow field data were measured on three characteristic profiles, each containing five measurement points collected by ADVPs configured as an array of two instruments. The determination of the operation parameters was done as a two-step process—calibration through the flume’s pump flow rate and verification with Acoustic Doppler Current Profiler RioGrande field data. Based on the results, the following setup for ADVPs’ operation parameters can be used to obtain reliable flow data in the scour hole next to the bridge pier: adaptive Ping Algorithm, Transmit Pulse Size of 4 mm and Cell Size of 1 mm.

Due to Typhoon Hagibis (Typhoon No. 19) in October 2019, also known as the Reiwa 1 East Japan Typhoon, many parts of the Chikuma River's levee in Nagano Prefecture were damaged. There were instances of levee collapse due to overtopping, and an electric railway bridge also collapsed when an eroded revetment broke. In the present study, these disasters were investigated. The investigation considered both the geology - geomechanics and the hydraulics of the levee collapse due to overtopping. The results suggest that the most significant factor in the collapse of the levee was structural weakness. There were cases in which the tenacity of a levee was improved by taking simple measures against seepage. It was found that the bridge abutments washed away mainly because the river levee became a water-colliding front due to changes in the water route following the erosion of a sandbar in the process of river level decline after the peak. [ABSTRACT FROM AUTHOR]

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The resilience-informed assessment for coastal highway bridges exposed to multiple hazards plays a crucial role in the decision-making process for their operation, maintenance, and management during the bridge's long-term service period. This study performs a seismic resilience assessment for a coastal reinforced concrete (RC) bridge under the combined effects of scour and uniform corrosion. Toward this goal, an extended pile shaft supported coastal RC bridge is taken as the benchmark and fifteen scenarios are generated to cover three regular scour conditions and five different corrosion levels. To inform the bridge management, the probabilistic distribution of the bridge service time corresponding to different corrosion levels is developed. Subsequently, the finite element model (FEM) for each scenario of the benchmark coastal highway RC bridge is developed, involving the soil-pile interaction and considering the uncertainty of structural and geotechnical parameters, as well as earthquake ground motions. The failure mode of the corroded extended pile shaft is identified as a flexural failure by comparing their flexural and shear capacities. Finally, a resilience loss ratio is proposed in this study for the first time to quantify the impacts of corrosion level and scour depth changes on seismic resilience across different ground motion intensities. Results indicate that both the seismic fragility and resilience decrease as the corrosion intensifies over time. Specifically, at a given intensity measure (IM) level, the resilience loss ratio increases as the corrosion level intensifies. For the studied benchmark bridge, the scour significantly increases the structural fundamental period, consequently reducing the curvature demand on the pile shaft. As a result, the scour generally decreases the failure probability and the earthquake-induced functionality loss for the extended pile shaft. As scour depth increases, the resilience loss of the bridge at a given corrosion level decreases. • Seismic risk and resilience of coastal bridges are assessed considering scour and corrosion. • Bridge service time distributions for different corrosion levels are derived. • Both pile foundation corrosion and soil-pile interactions are considered. • Corrosion level and scour depth effects on bridge's risk and resilience are studied. • Impact of corrosion level on extended pile shaft's curvature capacity is assessed. [ABSTRACT FROM AUTHOR]

Morphodynamic changes in the riverbed may be accelerated by the climate change-induced effects, mostly through the increase of the frequency of extreme climatic events such as floods. This can lead to scouring of the riverbed around the bridge substructure and consequently reduces its overall stability. In order to better understand hydromorphological processes at the local scale, the influence of floods on bridge scour requires a detailed analysis of several interacting flood hydrograph characteristics. This paper presents a multivariate analysis of the annual maximum (AM) flood discharge data at four gauging stations on the Drava and Sava Rivers in Croatia (Europe). As part of the hydrograph analysis, multiple baseflow separation methods were tested. Flood volumes and durations were derived after extracting the baseflow from measured discharge data. Suitable marginal distribution functions were fitted to the peak discharge (Q), flood volume (V) and duration (D) data. Bivariate copula analyses were conducted for the next pairs: peak discharge and volume (Q–V), hydrograph volume and duration (V–D) and peak discharge and hydrograph duration (Q–D). The results of the bivariate copula analyses were used to derive joint return periods for different flood variable combinations, which may serve as a preliminary analysis for the pilot bridges of the R3PEAT project where the aim is to investigate the influences on the riverbed erosion around bridges with installed scour countermeasures. Hence, a design hydrograph was derived that could be used as input data in the hydraulic model for the investigation of the bridge scour dynamics within the project and a preliminary methodology is proposed to be applied. The results indicate that bivariate frequency analysis can be very sensitive to the selected baseflow separation methodology. Therefore, future studies should test multiple baseflow separation methods and visually inspect the performance.

For bridges with surface foundations, scour is one of the main reasons for bridge failures. In regard to structural health monitoring, vibration-based scour detection techniques have received increasing attention over the past two decades. Scour occurs below the water surface in rivers or sea, leading to difficulty in equipment installation and maintenance. Recently, the concept of “drive-by” SHM using the indirect measurement of passing vehicle responses has been developed rapidly due to its convenience and low cost. This paper proposes a method to detect scour using the vehicle responses under an operational vehicle speed. The wavelet transform was applied to vehicle accelerations to obtain the wavelet energy. It was found that the wavelet energy increases with the increase in the scour damage level. However, the wavelet energy may also be affected by the on-site operating environments, such as sensor noise and other variabilities, which interferes with the identification of scour in practice. Hence, in this work, a statistical-wavelet-based approach was presented to effectively detect the presence of scour and even its location. The feasibility of the proposed approach is verified in both numerical simulation and lab experiments. The results show that the proposed method has a good potential to detect scour using indirect measurements.