Bridge Failure Research Articles

A generalized, model-free framework for assessing scour-induced bridge pier instability

Flood-induced scour is one of the leading causes of bridge failures in the United States, accounting for 53 % of recorded failures between 1989 and 2000. With many existing bridges considered “scour critical”, it is essential to closely monitor its development for effective mitigation. However, despite advances in scour hole measurement techniques, continuous monitoring of scour remains underused and little guidance is available to maintenance engineers to assess structural stability from scour depth measurements. This research presents a proof-of-concept, model-free bridge pier structural assessment framework. This framework is built on a library of bridge pier failure surfaces – curves that define failure limits for combinations of scour, wind, and flood loading for a range of structural configurations and site conditions. User input is limited to basic structural and site information, from which a corresponding failure surface is automatically selected, either directly or through interpolation between surfaces in the library. In this study, the creation of a failure surface library and framework is focused on pile bent pier designs, due to their widespread use. A broad scope of parameters was modeled such that common configurations of pier bent bridge designs and site conditions in Florida were considered. Sensitivity studies were performed to identify parameters for which modeling simplifications could be made to build the failure surface library with reduced computational burden. Results from three case study bridges are presented to verify that the resulting assessment framework maintained reasonable representation of structural response.

Influence of local scour on the dynamic response of bridges under barge collisions

The response assessment of bridges crossing navigable waterways under vessel collisions is commonly conducted assuming intact bridge models. However, local scour may occur at bridge foundations, which has been identified as one of the major hydraulic causes of bridge failures. Therefore, it is imperative to consider local scour in the design and analysis of bridges against vessel collisions. Many previous studies have focused on the bridge response under vessel collisions assuming deterministic scour depths with incremental values, without integrating a scour prediction modeling in the analysis. This work investigates the barge-bridge collisions in the presence of scour at pile foundations, by using empirical scour prediction models. The accuracy of each prediction model is evaluated using relevant laboratory test and field measurement records. Finite element (FE) models of a four-span continuous reinforced concrete (RC) bridge and a jumbo hopper barge are developed in LS-DYNA. The current study identifies the correlation between the upstream flow depth and the barge collision location in the analyses. Numerical results illustrate that both scour depth and collision location influence the displacement, shear force, and bending moment response of bridge piles. The struck bridge pier accommodates a considerably increased displacement with an increased scour depth, while the shear force and bending moment are primarily influenced by the collision location. The influence of scour on the barge-pier collision force is marginal. The maximum axial force in soil springs increases considerably with scour depth. The choice of scour prediction model shows a significant impact on the displacement, shear force, bending moment of piles, the displacement of struck pier, and the axial force of soil springs.

Shake table test on support uplift force of long-span cable-stayed bridge under longitudinal ground motions

Since the excessive seismic support uplift force may cause the support failure of long-span cable-stayed bridges, this study focused on the support uplift force at the auxiliary pier for a double-tower cable-stayed bridge with a main span of 1088 m. A shake table test was designed and performed based on the 1/35-scale test model scaled from the prototype bridge. Details of the test model, including the scale factor, structural member configurations, boundary conditions, and the numerical validation were briefly presented. The test results show that although only the longitudinal ground motion was applied, significant seismic support uplift and compression forces would be generated in the bearings at the auxiliary pier, resulting in the bearing uplift. The vertical vibration of the deck contributed by the first vibration mode of the test model was one of the main causes of the bearing uplift, but no rigid-like pounding effect occurred due to the vertical nonlinear mechanical behaviour of the bearing. Furthermore, the effect of the bearing uplift on the main seismic responses of the test model was negligible.

Effectiveness of composite energy dissipation restrainer on mitigating pounding and unseating failure of highway bridges

In earthquake-prone regions, large relative displacement between piers and girders may lead to pounding damage and unseating failure in highway bridges. To mitigate these effects, this study presents a composite energy dissipation restrainer (CEDR) that incorporates a composite energy tube (CET) as a fundamental component (comprising an aluminum honeycomb buffer and an expansion tube). The energy absorption characteristics of the CET are analyzed, and the influence of the aluminum honeycomb is thoroughly discussed. Furthermore, a design procedure and mechanical model for the CEDR, considering rare earthquakes, are developed. Finally, the effectiveness of the proposed design method and the behavior of limiting displacement of the CEDR are demonstrated through nonlinear time history analysis of an implemented project. The results reveal that the aluminum honeycomb buffer exhibits superior energy absorption capability, enhancing buffering efficiency and reducing damage. Compared to common cable-type restrainers (CCR), the CEDR reduces the relative peak displacement of the bridge by 40%, decreases the frequency of reciprocating displacement by 30% on average, and mitigates impacts on the abutment by 80%.

Drive-by Bridge Damage Detection Using Continuous Wavelet Transform

Bridges serve as vital engineering structures crafted to facilitate secure and effective transportation networks. Throughout their life-cycle, they withstand various factors, including diverse environmental conditions, natural hazards, and substantial loads. Recent bridge failures underscore the significant risks posed to the structural integrity of bridges. Damage detection techniques, being core components of structural health monitoring, play a crucial role in objectively assessing bridge conditions. This article introduces a novel framework for identifying damage in bridges utilizing continuous wavelet analysis of accelerations recorded using two sensors mounted on a vehicle traversing the bridge. The proposed method leverages changes in the static response of the bridge, which has proven to be more sensitive to damage than its dynamic counterpart. By doing so, the method eliminates the reliance on modal parameters for damage identification, addressing a significant challenge in the field. The proposed framework also addresses key challenges encountered by drive-by monitoring methods. It mitigates the adverse effects of road roughness by utilizing residual accelerations and efficiently detects and locates damage even in the absence of corresponding data from an undamaged bridge. Numerical investigations demonstrate the robustness of the proposed method against various parameters, including damage location and extent, vehicle speeds, road roughness levels, different boundary conditions, and multi-damage scenarios.

Mechanism of scour around two piers

AbstractScour around the bridge piers is the main cause of bridge failure below any bridge pier placed within the waterways. It is more than hundred years back a number of researchers described the vortex shedding phenomenon and the resulting Aeolian tones from a circular cylinder. Since then there have been a large number of investigations dealing with various aspects of this phenomenon. In many practical works and situations, flow takes place around more than one obstruction and objects in close proximity. Invariably in all these cases, interference effects occur and the forces on the obstructions are much influenced by these effects. These effects play a key role in the structures like flow-induced vibration of TV and transmission towers, and in many other practical situations. In this research paper the changes in the flow field that occur due to the interference effects are shown, analysed and the results as given in literature are compared with the present experimental work. The features have been brought out in this paper mainly make use of stand and geometry of circular cylinders in close proximity and the flow part of geometry in side by side arrangement.

Experimental Study of Pile Group Bridge Failure Mechanism Caused by Liquefaction-Induced Lateral Spreading

Experimental Study of Pile Group Bridge Failure Mechanism Caused by Liquefaction-Induced Lateral Spreading

Failures in Fixed Dental Prostheses: A Clinical Survey on Causes and Longevity

Crown and bridge failures are considered one of the most frequent challenges that dentists deal with on a daily basis. The aim of the current study was to assess the causes of failures in fixed dental prostheses in patients reporting to the dental clinics at Ahram Canadian University, Cairo, Egypt. Using a comprehensive clinical survey, causes of failures and serviceability patterns of the fixed dental prostheses (FDP) were explored in a sample of 80 patients (mean age 39.7±11) visiting the clinic for complications related to FDP. Patients were clinically and radiographically examined, and all symptoms related to their complaints were recorded. Descriptive analysis was performed, and SPSS version 22 was used for statistics. Results indicated that most of the failures were mechanical in nature (30%), followed by biological failures (20%), and then aesthetics reasons (11%). 45.7 % of the FDP served for 1-5 years, 28.6 % served for 6-12 months, 14.30% served for more than 5 years, while the least numbers of prostheses (11.4%) served for less than 6 months. Proper patient selection, diagnosis, and treatment planning is essential to maintain and increase the longevity of FDP. It is also crucial to educate patients about good dental hygiene and prosthesis maintenance as well as for the dentist to fully recognize the disadvantages of each dental material to prevent the problems they induce and be able to make the best decision.

Scouring around bridge pier: A comprehensive analysis of scour depth predictive equations for clear-water and live-bed scouring conditions

Abstract The failure of bridges, attributed to bridge pier scouring, poses a significant challenge in ensuring safe and cost-effective design. Numerous laboratory and field experiments have been conducted to comprehend the mechanisms and predict the maximum equilibrium scour depth around bridge piers. Over the last eight decades, various empirical methods have been developed, with different authors incorporating diverse influencing parameters that significantly impact the estimation of equilibrium scour depth around bridge piers. This paper aims to consolidate: (1) available experimental and field data sets on different types of bridge pier scouring, (2) the influence of flow and roughness parameters on both clear water scouring (CWS) and live bed scouring (LBS), and (3) existing empirical equations suitable for computing equilibrium scour depth around a bridge pier under CWS and LBS conditions. The presented research encompasses over 80 experimental/field data sets and more than 60 scour-predicting equations developed for CWS and LBS conditions in the past eight decades. Based on the performance of different empirical models in predicting scour depth ratio, suitable models are recommended for CWS and LBS conditions.

Ultimate Load-Bearing Capacity and Sustainable Performance of Pile Foundations of Yanji Suspension Bridge in Fault Zone Based on Refined Geological Model

Pile foundation is the most important foundation type of long-span bridges, of which the ultimate load-bearing capacity affects the safety and sustainable performance of bridges. When constructing large-span bridges, the bridge site may be close to the adjacent fault zones, which seriously affects the safety and long-term performance of pile foundations, causing the failure and unsustainability of long-span bridges in their life-cycle service life. At present, there are no engineering design rules or methods for assessing the load-bearing capacity of the pile foundation near the fault zones. To study the influence of the fault zone on the loading-bearing capacity and sustainable performance of pile foundations, triaxial compression tests were carried out on the mylonite at the Yanji suspension bridge site near the Xiangfan–Guangji fault zone in Hubei Province. The mechanical properties of mylonite were reflected by the Mohr–Coulomb yield criterion, and a topographic and geological modeling method based on the multi-platform was established. Then, the ABAQUS finite element software was used to study the deformation, stress, failure modes, and sustainable performance of the pile foundation under different bridge load levels, analyze the safety of the pile foundation in the fracture zone, and summarize the ultimate bearing characteristics of the pile foundation. The results show that the whole pile and surrounding rock are basically elastic under the pressure of the designed load, the plastic zone of the pile foundation is mainly concentrated at the pile bottom, and the shear stress concentration zone of the pile is mainly manifested in the joint of the cap and pile and the interface between soft and hard rock. When the load is increased to 4 times the designed load, the stress concentration area of the pile body gradually shifts upward from the pile bottom, and the surrounding rock at the bottom forms an “X-shaped” shear failure zone. After 100 years of operation, the maximum compressive stress of piles reaches 28.6 MPa, which is 120% higher than that at the beginning of the bridge construction, indicating that the sustainable performance of the piles can withstand the effect of the fault zone over the designed service years.

Computer Vision-Based Real-Time Identification of Vehicle Loads for Structural Health Monitoring of Bridges

Coupling effects of various loading conditions can cause deflections, settlements and even failure of in-service bridges. Although it is one of the most critical loads, unfortunately, loading conditions of moving vehicles are difficult to capture in real time by bridge monitoring systems currently in place for sustainable operation. To fully understand the status of a bridge, it is essential to obtain instantaneous vehicle load distributions in a dynamic traffic environment. Although there are some methods that can identify overweight vehicles, the captured vehicle-related information is scattered and incomplete and thus cannot support effective bridge structural health monitoring (BSHM). This study proposes a noncontact, vision-based approach to identification of vehicle loads for real-time monitoring of bridge structural health. The proposed method consists of four major steps: (1) establish a dual-object detection model for vehicles using YOLOv7, (2) develop a hybrid coordinate transformation model on a bridge desk, (3) develop a multiobject tracking model for real-time trajectory monitoring of moving vehicles, and (4) establish a decision-level fusion model for fusing data on vehicle loads and positions. The proposed method effectively visualizes the 3D spatiotemporal vehicular-load distribution with low delay at a speed of over 30FPS. The results show that the hybrid coordinate transformation ensures that the vehicle position error is within 1 m, a 5-fold reduction compared with the traditional method. Wheelbase is calculated through dual-object detection and transformation and is as the primary reference for vehicle position correction. The trajectory and real-time speed of vehicles are preserved, and the smoothed speed error is under 5.7%, compared with the speed measured by sensors. The authors envision that the proposed method could constitute a new approach for conducting real-time SHM of in-service bridges.

Advanced Hydrodynamic Modelling of Flow at a River Bridge: Insights from 3D Computational Fluid Dynamics

Failure of river bridges is often due to hydraulic reasons, such as the development of severe scouring around piers and abutments. In many cases, the presence of bridge structures produces complex flow fields, which are difficult to predict using standard hydraulic models. This entails difficulties in estimating the hydrodynamic actions on the structure and the potential scour on the riverbed. A three-dimensional Computational Fluid Dynamics (3D CFD) model is used to analyze the flow field and the bed shear stresses at an existing bridge. The Volume of Fluid (VoF) method allows resolving the deformable free-surface, and the Detached Eddy Simulation (DES) approach allows resolving the dynamics of the energetically important turbulent eddies in the flow. The analysis deals with modeling the flow around a realistic, full-scale, multi-pier bridge in the Po River. Simulations considered different hydrodynamic regimes, i.e., the free-surface flow regime and the hypothetical pressure-flow regime which would occur when water levels are higher than the low chord of the bridge deck. The numerical application highlights the potential of the DES technique for analyzing the hydrodynamics of flow at bridges in natural river channels. Besides the turbulent flow fields and the description of the vortical structures, relevant results include the time-varying spatial distribution of the hydrodynamic forces acting on the different parts of the bridge and the time-varying distribution of the shear stress on the bed. This aspect is of particular interest because i) the estimation of drag forces on the structure components may be oversimplified using canonical, averaged formulas, and ii) the fluctuations in time of the bed shear stresses play a key role in determining the removal of sediments from the bed and the scour hole close to the bridge piers.

Dynamic characterization of a curved nine-spans pre-stressed concrete box girder bridge with half-joints

In recent years, the failure of many bridges has pressed governments all over the world to increase investments and to enact new monitoring regulations. In the Italian context, the Ministry of Infrastructure and Transport answered to that challenge by enacting the new Guidelines on Risk Classification and Management, Safety Assessment and Monitoring of Existing Bridges, in 2022. In this new regulation, Structural Health Monitoring (SHM) plays a fundamental role, complementing traditional periodic inspections by carrying out low intrusive non-destructive analyses. In this field, Operational Modal Analysis (OMA) is a vibration-based method consisting in the processing of the ambient accelerations recorded on the structure in order to extract and track its modal features. The final goal of continuous OMA is the timely identification of possible damage-induced persistent variations in the modal features of the monitored structure. This is why one of the most recent advances in OMA algorithms is related to the development of continuous Automated OMA embedded in high-potential software, to enable the infrastructure management authorities to realize large-scale monitoring of bridge networks. Many road bridges are however long multi-span bridges which require numerous sensors for their monitoring, thus making automated OMA especially challenging from the computational point of view. The aim of the work is to contribute to a more computationally affordable automated OMA for long bridges, by proposing to subdivide the OMA task considering suitable selections of subgroups of sensors. The proposed approach is illustrated in a case study consisting of a curved nine-spans pre-stressed concrete box girder bridge with 10 half-joints and equipped with more than 50 sensors.

Effects of Floating Debris on Flow Characteristics around Slotted Bridge Piers: A Numerical Simulation

Bridge pier scouring is a significant concern in hydraulic engineering, requiring thorough investigation under various conditions to estimate maximum scour depth and mitigate the risk of bridge failure. This study aims to conduct a numerical simulation of flow around a bridge pier with slots in the presence of floating debris, with the objective of analyzing variations in parameters such as velocity, shear stress, turbulent intensity, and turbulent kinetic energy. The FLOW−3D software package (Version 11), along with the k−ε (RNG) turbulence model, was employed for the simulation. The results indicate that the presence of a slot in the bridge pier provided a smooth pathway for the flow, resulting in a reduction in the pressure gradient and alleviating the negative impacts on the flow. This, in turn, led to a decrease in the velocity of the flow. Additionally, turbulence intensity around the pier ranges between 0 and 49, while turbulent kinetic energy varies from 0 to 0.005. The findings reveal that models without slots exhibit higher turbulence and vorticity levels, as well as greater flow separation, compared to models with slots. This disparity can be attributed to the slot’s ability to neutralize detrimental lateral and downward flows. Furthermore, the results demonstrate a gradual decrease in shear stress as the flow approaches slotted bridge piers, accompanied by a reduction in vortex intensity. These findings suggest that the accumulation of floating debris can counteract the influence of slots in reducing scour around bridge piers, necessitating thorough consideration during the design phase.

River channel dynamics and flooding: A case of motorable bridge collapse due to abrupt flood in Chhabdi Khola, Tanahun, Nepal

The monsoon season in Nepal brings calamitous events like riverbank erosion, toe cutting, and the structural failure of bridges due to floods. In July 2021, a motorable bridge in Bhadgaun, Tanahun district, Nepal, collapsed during a massive flood in Chhabdi Khola. The study aims to comprehensively document the aftermath, specifically focusing on the causal factors that led to the damage of the Chhabdi Khola Dovan Bridge. The study delves into an in-depth analysis of the stream's channel morphology, with the 5.85 kilometers Chhabdi Khola partitioned into 28 distinct segments, each spanning approximately 200 meters. These segments, sequentially labeled from Site 1 to Site 28, encompass the area extending from the upstream at Chhabdi Barah temple to the downstream at bridge’s location. Rigorous measurements of length, breadth, and depth at each site form the basis for volumetric assessments of the stream. The study revolves around contrasting paleo channel attributes with contemporary alterations within the Chhabdi Khola catchment. The analysis leverages precipitation data sourced from the Department of Hydrology and Meteorology (DHM) to discern precipitation trends within the Chhabdi Khola catchment area. The hydrographic data underwent trend analysis utilizing Mann-Kendall and Sen's slope method through R software (version 4.3.2). The collapse of the Chhabdi Khola Dovan Bridge resulted from intense water flow and debris due to heavy rainfall and a narrow outlet near the bridge, impacting the local population and land users facing the enduring aftermath of a catastrophic monsoon event. The study highlights the significance of understanding river dynamics in small streams and advocates for proactive disaster preparedness measures, even in seemingly small river channels.

Identifying and estimating causal effects of bridge failures from observational data

This paper presents a causal analysis aimed at identifying and estimating causal effects with regard to bridge failures under extreme events. Observational data on about 299 bridge incidents were used to conduct this causal investigation and examine bridges’ performance. As causal investigations can also deliver counterfactual assessments of parallel worlds, a causal analysis can serve as a high-merit methodology to evaluate the performance of critical bridges. Our findings quantify the causal impacts of various factors spanning the characteristics of bridges, traffic demands, and incident type (i.e., fire, high wind, scour/flood, earthquake, and impact/collision). More specifically, our analysis reveals high causal effects related to the used structural system, construction materials, and demand served.

Tension-shear extension criteria used in PFC2D to reveal a brittle failure of rock bridges in rock slopes with stepped joints

Stepped failure is a typical mode in alpine valleys and usually manifests as brittle fractures determined by joints. Tension-shear extension criteria were proposed to reflect the intrinsic mechanism of this failure mode. These criteria combined the theory of linear elastic fracture mechanics and the Mohr-Coulomb (M−C) strength criterion, including propagation trends and fracture conditions, and reflected the fracture behavior of rock bridges determined by joints. The proposed extension criteria were numerically applied in the 2D Particle Flow Code (PFC2D). The mesoscopic strength parameters were calibrated according to a mathematical relationship, which could satisfy the relationship between stress and strength with the proposed criteria. For massive rock slopes dominated by stepped joints, it is determined through theoretical and experimental analysis that rock bridges undergo tensile failure under low normal stress levels, which gives a reasonable explanation of why rock bridges observed in situ generally undergo tensile fracture. The internal mechanism of rock bridge failure is revealed through mechanical analysis of fracture behavior, which is considered in the numerical method. Taking the Xiaowan Hydropower Station as an example, it is confirmed that the simulation results truly reproduce the mesoscopic mechanism of the stepped failure of the slope.

A forensic investigation of progressive bridge collapse under floods and asymmetric scour validated by incident video footages

Hydraulic bridge failures generally occur abruptly and are unpredictable, which leads to difficulties in tracing causes due to the unavailability of the actual structural and conditional state at the collapse moment. Previously, research primarily concentrates on the forensic analysis of structure but ignores the hydrological issues. However, the critical point in deducing the cause of a hydraulic bridge failure is to understand the structural response under the hydraulic loading effects. A proposed numerical solver enables the simulation of hydraulic bridge failures considering both the structural and hydraulic aspects. A hollow overhanging arch bridge in Heyuan of Guangdong Province collapsed during the flood season on 14 June 2019. This paper presents a forensic analysis of the collapse based on the numerical solver and validates the result by incident video footages. The proposed solver is demonstrated to have high performance in assisting the forensic investigation of hydraulic bridge failures considering the hydrodynamic-soil–structure interaction. The hybrid model results show that the possible causes of the Heyuan Dongjiang Bridge collapse are the asymmetrical scour and the material degradation of the arch springs.

Operation of Dual-T-Type Modular Multilevel Converter for Uninterrupted Power Supply Under Bridge Failures

Dual-T-type modular multilevel converter (DTMMC) is an alternative for existing uninterrupted power supply (UPS) due to its advantage in flexible leg reusing, multiple power ports and high operating efficiency. In this paper, a DTMMC-UPS which has series configurations on both input/output AC sides obtain high voltage grid/ load accessing interfaces is presented. In the described system, the fact that copies of T-type legs are employed makes the semiconductor failure common to happen. Moreover, both the coupling between rectifier and inverter conversions, and the confliction between inter-cell and inner-cell voltage balancing make the fault-tolerant control a tough issue. In this paper, the switch fault types are firstly clarified and diagnosed by the different impacts on the normal operating. An improved voltage vector modulation is then deduced to facilitate the planning of proper primary switching patterns, to achieve rectifier side normal operation. The secondary alternated LS-PWM is also modified to achieve inverter side normal operation. The experiment results are supplied to verify the validity of the modulation coordinated fault toleration strategy.

Scour Evaluation Using HEC RAS Model: A Case Study On Musiri Bridge, Trichy, India

Bridge scour is a natural phenomenon that can cause serious damage to infrastructure. It occurs when water flows around bridge piers or abutments, eroding the soil or sediment that supports them. This can lead to structural failure, which poses a significant risk to public safety. To mitigate this risk, engineers must design bridges with scour in mind, taking into account factors such as flow velocity, sediment transport, and erosion resistance. In doing so, they can ensure that our infrastructure remains safe and sustainable for years to come. Bridge scour evaluation is a crucial step to assure the structure’s safety and integrity. There are several approaches to designing, evaluating, and inspecting bridges for scour. Scour assessment is significant since it might jeopardize the bridge’s integrity. Floods scouring bed material surrounding bridge foundations are the most prevalent cause of bridge failures. Proper scour analysis is required as scour has found to be a serious threat to bridge structures since it increases the risk of collapse of bridge. Moreover, scour seriously affects the capacity of the bridge and causes structural damage. This research focusses on the scour analysis of Musiri bridge (Thanthai Periyar bridge) located on Cauvery River in Trichy. The bridge is subjected to local scour. Hydraulic Engineering Centre, River Analysis Simulation (HEC-RAS) software is used to analyze the effect of scour at different cross sections of the river, both in upstream and downstream. A planform analysis has been done across the bridge for a time period of over 10 years using open-source satellite data with the help of Quantum Geographic Information System (QGIS) software. This centre line of the river across the bridge is mapped across different years to understand the effect of scour for the period of 2013 to 2023. Remedial measures have been suggested to combat the effect of scour in the study area. Bridges are just one piece of a larger puzzle, and their construction and maintenance have environmental and social impacts that must be carefully managed. Hence, it’s important to consider the broader implications of infrastructure development and it should ensure safe and simple design of bridge constructions so that the infrastructure investments can benefit both present and future generations.