•Novel fragility models for scoured-critical bridges exposed to multiple hazards were generated•Rigorous FEM included the water-soil-bridge interaction under flooding and earthquakes•Failure modes ...for bridge components exposed to floods were described•Insights on the flood vulnerability of integral and bridges with bearings are provided•Consideration of uncertainties in scour formation enhance the reliability of risk assessment
Building resilient bridges, that are able to withstand multiple natural stressors with minimal damage and quickly restore their functionality is paramount to delivering climate-resilient transport infrastructure. Nevertheless, bridges are proven to be vulnerable to natural hazards, with floods and earthquakes being the main causes of failure. The available research and practice for assessing the vulnerability of river-crossing bridges is predominantly qualitative and therefore relies heavily on visual inspections, while ignoring important characteristics of the complex water-soil-bridge interaction. This is a knowledge gap that this paper aims to fill. This work provides novel fragility models for hydraulically induced stressors and/or combinations of hydraulic and seismic hazards. To achieve this, unique detailed two- and three- dimensional numerical models are employed, for a typical three-span prestressed box-girder river-crossing bridge. This paper is a primer on the vulnerability of flood-critical bridges as it models the entire water-soil-bridge system, taking into account critical hydraulic stressors (scour, debris accumulation, hydraulic forces), the uncertainty in scour hole formation, and all components of integral and isolated bridges: deck, bearings, piers and abutments, backfill, and the foundation soil. A detailed description of the damage modes for each component is given and sets of fragility curves for floods and combinations of hydraulic stressors and earthquakes are developed. The study concludes that integral bridges are in most cases more vulnerable to local scour than bridges with bearings, since the latter are more flexible and can therefore adapt to changes in their geometry. The opposite is true for global scour and/or seismic earthquake excitations. The generated fragility models are useful tools for quantitative risk assessment of transport systems and provide practical means in resilience-based asset management by owners and operators of transport infrastructure.
•Introduce artificial neural network for regional seismic risk assessment of skewed bridges.•Develop multi-dimensional fragilities for California bridges via artificial neural network.•Reduce ...computational efforts for developing bridge-class fragility curves.•Estimate the seismic vulnerability of skewed bridges.
Recent researches are directed towards the regional seismic risk assessment of structures based on a bridge inventory analysis. The framework for traditional regional risk assessments consists of grouping the bridge classes and generating fragility relationships for each bridge class. However, identifying the bridge attributes that dictate the statistically different performances of bridges is often challenging. These attributes also vary depending on the demand parameter under consideration. This paper suggests a multi-parameter fragility methodology using artificial neural network to generate bridge-specific fragility curves without grouping the bridge classes. The proposed methodology helps identify the relative importance of each uncertain parameter on the fragility curves. Results from the case study of skewed box-girder bridges reveal that the ground motion intensity measure, span length, and column longitudinal reinforcement ratio have a significant influence on the seismic fragility of this bridge class.
Integral bridges are a class of bridges with integral or semi-integral abutments, designed without expansion joints in the bridge deck of the superstructure. The significance of an integral bridge ...design is that it avoids durability and recurring maintenance issues with bridge joints, and maybe bearings, which are prevalent in traditional bridges. Integral bridges are less costly to construct. They require less maintenance and therefore cause less traffic disruptions that incur socio-economic costs. As a consequence, integral bridges are becoming the first choice of bridge design for short-to-medium length bridges in many countries, including the UK, USA, Europe, Australia, New Zealand and many other Asian countries. However, integral bridge designs are not without challenges: issues that concern concrete creep, shrinkage, temperature effects, bridge skew, structural constraints, as well as soil–structure interactions are amplified in integral bridges. The increased cyclic soil–structure interactions between the bridge structure and soil will lead to adverse soil ratcheting and settlement bump at the bridge approach. If movements from bridge superstructures were also transferred to pile-supported substructures, there is a risk that the pile–soil interactions may lead to pile fatigue failure. These issues complicate the geotechnical aspects of integral bridges. The aim of this paper is to present a comprehensive review of current geotechnical design practices and the amelioration of soil–structure interactions of integral bridges.
Buildings play an indispensable role in urban development. As typical structures of transportation buildings, bridges serve as crucial nodes in connecting different regions, promoting economic ...growth, and ensuring social security. However, with the extension of their service life, the performance of bridges will inevitably decline. Performance monitoring and evaluation are crucial during the life cycle of bridges. The accelerating convergence of civil engineering, materials science, and artificial intelligence has sparked the interest of researchers from different disciplines in the emerging field of bridge state perception. This reprint covers topics on condition monitoring and assessment of engineering structures, featuring 13 papers. These studies provide some novel methods, models, and technological applications for bridge condition perception, which are of great significance for the design, construction, and assessment of bridges.
Three-dimensional (3D) geometric bridge models play an important role in bridge inspection, assessment, and management. Laser scanning nowadays offers a cost-efficient method to capture dense, ...accurate 3D topographic data of surfaces of the bridge. However, given the typical complexity of bridges, current workflows using commercial software to construct a bridge model still require intensive labour work. This paper presents a new approach to automatically extract the point cloud of surfaces of structural components of box and slab-beam bridges. The proposed method consists of 3 Parts: (1) point-to-surface, (2) superstructure and (3) substructure extraction. The method uses both spatial point clouds and contextual knowledge to extract point cloud subsets corresponding to surfaces of individual bridge components in a consecutive order from superstructure to substructure. For each bridge component, two levels of extraction are (1) coarse extraction to separate candidate points of the component from the full data set and (2) fine filtering to obtain final 3D points of individual surfaces using cell- or voxel-based region growing (CRG or VRG), followed by a connected surface component (CSC) method. An experimental test on one box-girder and one slab-beam bridges shows that the proposed method successfully extracts all surfaces of bridge components with the lowest F1-score of 0.93 based on a point-based evaluation. Moreover, a shape similarity evaluation also shows that discrepancies between extracted surfaces and ground truth ones are no larger than 0.82 for the area overlap ratio and 0.59 degrees for the angular deviation. The proposed method contributes to the automatic generation of 3D geometric bridge models and to give point clouds of individual surface for damage identification.
•Propose a new approach to extract point clouds of individual surfaces of a bridge•Propose cell-based region growing to extract point clouds of planar surfaces•Develop two levels of surface extraction allowing to handle a massive data set•Present a methodology to estimate input parameters for processing point clouds•Succeed to extract surfaces of bridge components with the lowest F1-score above 0.93
In recent years there has been renewed interest on integral abutment bridges (IABs), mainly due to their low construction and maintenance cost. Owing to the monolithic connection between deck and ...abutments, there is strong soil‐structure interaction between the bridge and the backfill under both thermal action and earthquake shaking. Although some of the regions where IABs are adopted qualify as highly seismic, there is limited knowledge as to their dynamic behaviour and vulnerability under strong ground shaking. To develop a better understanding on the seismic behaviour of IABs, an extensive experimental campaign involving over 75 shaking table tests and 4800 time histories of recorded data, was carried out at EQUALS Laboratory, University of Bristol, under the auspices of EU‐sponsored SERA project (Seismology and Earthquake Engineering Research Infrastructure Alliance for Europe). The tests were conducted on a 5 m long shear stack mounted on a 3 m × 3 m 6‐DOF earthquake simulator, focusing on interaction effects between a scaled bridge model, abutments, foundation piles and backfill soil. The study aims at (a) developing new scaling procedures for physical modelling of IABs, (b) investigating experimentally the potential benefits of adding compressible inclusions (CIs) between the abutment and the backfill and (c) exploring the influence of different types of connection between the abutment and the pile foundation. Results indicate that the CI reduces the accelerations on the bridge deck and the settlements in the backfill, while disconnecting piles from the cap decreases bending near the pile head.
•Three-step risk-based methodology for bridge foundations scour evaluation.•Hydrological modeling incorporates model uncertainty by using an aver-aging approach.•Main flow characteristics are ...simulated with the open-source HEC-RAS model.•Bridge scour assessment takes advantage of HEC-RAS scour module.•Methodology can be potentially incorporated into regular bridge inspection schedules.
The collapse of bridges inevitably leads to economical losses and may also be responsible for human fatalities. A bridge may fail due to several reasons, with local scouring around its foundation being the most common. Despite decades of scouring research, there are still many uncertainties affecting the design process of bridge piers. The most critical and least explored are the hydrological and hydraulic variables. The recent intensification of floods may also increase the vulnerability of bridges to scour effects. Therefore, the present work aims to propose a risk-based methodology for considering scour at bridge foundations. It is composed of three main steps: (i) assessing extreme hydrological events (hazards); (ii) modeling river behavior through the computation of flow characteristics and bridge scour depths; and (iii) assessing bridge scour risk by associating its scour depth to foundation depth ratio with the priority factor (vulnerability) and assigning a qualitative evaluation of the scour risk rating (level of risk). The hydrological modeling incorporates uncertainty with an averaging approach in the design floods definition. The flow characteristics are simulated with the HEC-RAS model, which also contains a scour module for bridge scour assessment. However, other empirical estimates are considered for simple and pile-supported foundations. This study ends with a qualitative assessment of how the scouring phenomenon affects bridge vulnerability and its safety. The proposed risk-based methodology - validated through a case study, the new Hintze Ribeiro bridge in Portugal - can be potentially incorporated into regular bridge inspection schedules as a useful tool for risk management measures, assisting in catastrophic events’ prevention.
Summary
Vision‐based monitoring receives increased attention for measuring displacements of civil infrastructure such as towers and bridges. Currently, most field applications rely on artificial ...targets for video processing convenience, leading to high installation effort and focus on only single‐point displacement measurement, for example, at mid‐span of a bridge. This study proposes a low‐cost and non‐contact vision‐based system for multipoint displacement measurement based on a consumer‐grade camera for video acquisition and a custom‐developed package for video processing. The system has been validated on a cable‐stayed footbridge for deck deformation and cable vibration measurement under pedestrian loading. The analysis results indicate that the system provides valuable information about bridge deformation of the order of a few centimetres induced, in this application, by pedestrian passing. The measured data enable accurate estimation of modal frequencies of either the bridge deck or the bridge cables and could be used to investigate variations of modal frequencies under varying pedestrian loads.
Diagnostic load testing refers to the use of the measured historical responses of the structure in the field data to better understand its dynamic and static structural behaviours. It is important ...and necessary to predict the health state, load capacity, and aging of the structure by updating the finite element (FE) model, which can give useful information to aid the design of retrofits and the maintenance of the existing bridge in the future. The paper presents an update of the full-scale FE model for the reinforced concrete (RC) bridge structure over the seawater river based on the experimental strains under the static load testing in which the representative FE model of the actual structure is determined from the optimisation procedures. The optimisation variables are applied, including the cross-sectional properties and concrete material calibrated through the genetic algorithm (GA) optimisation in the MATLAB software, which interfaces with the FE modelling in the scripting of the SOFISTIK TEDDY software automatically. The bending moments at the mid-span of the RC girders are determined in the FE modelling to compute stresses, which are compared with the measured stresses through optimisation scenarios with a percentage error of the objective function less than 10%. The measured data of concrete strains are recorded from reusable strain transducers installed on the mid-span girders for every bridge span, which are used to calibrate the bridge model in static load testing. The novelty of the solution is to implement innovative techniques using field data as an improved approach for calibrating automatically the analytical FE model parameters of all RC spans of the bridge until its static behaviours are very similar to those of the actual bridge. The final updated FE modelling is used to apply truck load configurations according to bridge design standards such as the AASHTO specifications, which can predict the load limits of the existing bridge structure more accurately and reliably. These proposed approaches can be applied to large bridges as well as complex structures with supporting FE analysis software and data processing software.
PDF
