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Vehicle scanning methods are gaining popularity because of their ability to identify modal properties of several bridges with only one instrumentation setup, and several methods have been proposed in the last decade. In the numerical models used to develop and validate such methods, bridge damping is often overlooked, and its impact on the efficacy of vehicle scanning methods remains unknown. The present article addresses this knowledge gap by systematically investigating the effects of bridge damping on the efficacy of vehicle scanning methods in identifying the modal properties of bridges. For this, acceleration responses obtained from a numerical model of a bridge and vehicle are used. Four different scenarios are considered where vehicle damping, presence of road roughness, and traffic on the bridge are varied. Bridge damping is modeled using mass-proportional, stiffness-proportional, and Rayleigh damping models. The impacts of ignoring bridge damping or considering one of these damping models on the modal frequencies and mode shapes identified using the vehicle response are investigated by comparing the results. The outcomes of the numerical analysis show that ignoring bridge damping in vehicle scanning applications can significantly increase the efficacy of these methods. They also show that the identifiability of the bridge frequencies and bridge mode shapes from the vehicle response decreases significantly when bridge damping is considered. Further, the damping model used impacts which bridge modes can be identified because different damping models provide different modal damping ratios for each mode. The results highlight the importance of correctly simulating damping behavior of bridges, which is often ignored, to be able to correctly evaluate the efficacy of vehicle scanning methods, and they provide an important stepping stone for future studies in this field. [ABSTRACT FROM AUTHOR]

Steel corrosion is by far the biggest durability issue for many reinforced concrete bridge structures worldwide. The columns in these bridges can be critical, especially for seismic resistance. In this study, glass-fibre-reinforced-polymer bars were investigated as an alternative to steel for sustainable and resilient bridge construction. As lateral reinforcement is more susceptible to corrosion, and structures fully reinforced with fibreglass bars display softer responses with lower shear and flexural capacity, fibreglass spirals and longitudinal steel reinforcement were used in the tested columns. The experimental programme included the design, construction and seismic testing of full-scale (508 mm diameter) and half-scale (356 mm diameter) columns. The other variables investigated were the axial load and the amount and spacing of spirals. For both column sizes, fibreglass spirals provided increasing confining pressure to the concrete core with increased deformations. For the full-scale columns, no adverse size effects were observed in comparison to the half-scale columns. The columns produced large ductility and energy dissipation. Results from selected representative specimens are presented here to establish the feasibility of using fibreglass spirals in circular bridge columns. Resilience can thus be built into new columns through innovative durable fibreglass lateral reinforcement, with similar if not superior behaviour to steel-reinforced columns. [ABSTRACT FROM AUTHOR]

Multi-span bridges having a bidirectional ductile diaphragm consisting of buckling-restrained braces (BRBs) can provide resilient bridges with damage-free columns, at low cost, while minimising displacement demands to levels that can be easily accommodated. Towards the goal of better understanding the behaviour of this type of bridge and its advantages, a parametric analysis was performed considering regular multi-span simply supported bridges with variations in pier stiffness, BRB target displacement, BRB yield displacement and numbers of spans. The bridges were analysed in the longitudinal direction. BRBs were designed using non-linear response history analysis. The demands of the designed bridges were analysed to understand the influence of the various parameters considered. The proposed system was able to reduce the demands in piers so as to keep them elastic and limit the displacement demands in expansion joints (making it easier to prevent unseating in retrofit situations). It was also found that, according to fatigue damage calculations, it is not necessary to replace BRBs after an earthquake. [ABSTRACT FROM AUTHOR]

A new consolidation system for prestressed reinforced concrete (PSRC) beams of girder bridges is presented and evaluated. The system consists of two arch-shaped steel trusses placed alongside the lateral faces of the beam to be consolidated. The arches develop longitudinally along the entire span of the beam and in elevation using the available height of the PSRC cross-section. The consolidation system is characterised by its own external constraints, independent from those serving the pre-existing element. The efficiency of the system with respect to variable parameters is examined, focusing on the ratio between the load discharged by the consolidation system and the total applied load. Referring to a case study, consolidation of a PSRC beam adopting the proposed system is compared with the usually adopted external prestressing technique. The cross-sectional properties of the steel arch-shaped trusses are defined by means of a structural optimisation process using a genetic algorithm to identify the minimum steel consumption. Finally, a preliminary cost–benefit analysis is performed for the proposed solution and compared with other commonly adopted techniques. [ABSTRACT FROM AUTHOR]

The Canadian highway bridge design code (CHBDC) uses the concept of a target reliability index for evaluating the load-carrying capacity of existing bridges. This index, which is based on risk to human life, is related to three aspects of uncertainties inherent in a bridge: element behaviour, system behaviour and inspection level. Analysis is yet another uncertainty in bridge evaluation. It is assumed that all bridge inspections are manual. Citing examples of tests on many instrumented bridges, another level of inspection is proposed, carried out with the help of electronic instruments and tests under controlled vehicle loads. Simple additions to the clauses of the CHBDC are proposed, which can be used to determine the optimum load-carrying capacities of existing bridges where structural monitoring information is available. [ABSTRACT FROM AUTHOR]

Soil–structure interaction can significantly affect the seismic vulnerability of systems through several mechanisms that depend on the mutual effects of the soil properties and the structural characteristics. In this work, a probabilistic-based approach was applied to evaluate such effects on the fragility of an isolated bridge representing a typical Californian highway bridge. Analytical fragility curves were developed using OpenSees, implementing hysteretic materials and advanced plasticity models to represent non-linearity. The mutual non-linear effects of soil deformability and isolation on the system (soil–foundation–structure) were assessed by considering several limit states for the column ductility and the deck displacement. [ABSTRACT FROM AUTHOR]

Bridges are fundamental links for the movement of goods and people and bridge damage can thus have significant impacts on society and the economy. Earthquakes can be extremely destructive and can compromise bridge functionality, which is essential for communities. Evaluation of bridge functionality is thus fundamental in the planning of emergency responses and socioeconomic recovery procedures. It is especially useful to define parameters to assess investments in bridge infrastructure. Resilience is a key parameter that can identify decision making procedures necessary for recovery investments. In this regard, resilience can be defined as the rapidity of a system to return to pre-disaster levels of functionality. This aim of this work was to assess the lack of robust analytical procedures for quantifying systematic restoration for earthquake-damaged bridges, to provide a link between the assessment of resilience and its application in decision making approaches. The proposed methodology (called seismic resilience for recovery investments of bridges) uses functionality–time curves that allow quantification of resilience along with readable findings for a wider range of stakeholders. The results presented in this paper should be of interest to multi-sectorial actors (i.e. bridge owners, transportation authorities and public administrators) and could drive interdisciplinary applications such as the assessment of recovery techniques and solutions. [ABSTRACT FROM AUTHOR]

Foundation scour has been a reason for several cases of river-bridge earthquake-induced failure during recent decades. However, practising engineers often do not consider its direct effect on the seismic design procedure of such structures. The cavity around a bridge foundation is a random phenomenon depending on several uncertain parameters. This study provides a probabilistic platform to investigate the effect of random scouring on the seismic performance of a particular bridge. The procedure is implemented on an existing multi-span reinforced concrete bridge. To this end, the Monte Carlo simulation technique is utilised to generate samples of the random variables of the scour model to develop the scour hazard curve. A common type of reinforced concrete multi-span bridge is considered as a model. The Latin hypercube sampling method is employed to generate random scouring scenarios in the finite-element model, including uniform and non-uniform scour. Then, fragility curves are developed utilising cloud dynamic analysis. The results reveal that the scouring pattern is one of the most crucial sources of uncertainty. In most circumstances, uniform scour scenarios are more effective than the average of non-uniform cases. However, in some specific patterns, the effect of non-uniform scouring is dominant. [ABSTRACT FROM AUTHOR]

When traffic flows pass through existing bridges, the dynamic effect of the vehicle loads increases due to the local surface damage rather than the entire roughness level of the bridge deck. This study presents a method for evaluating a dynamic impact factor (IM) from a bridge dynamic response under a traffic flow considering the local surface damage. The random axle loads of traffic vehicles under the deteriorated roughness conditions are presented using an input load time-history applied to each discretized deck node of a finite element bridge model. The amplification ratios of the root mean square of the simulated acceleration under nominal road surface conditions with respect to the specified IMs in the design stage are calculated. The relationship between the ratios and IMs is determined to evaluate the dynamic impact factors under any surface roughness condition. The method is validated by applying it to two existing bridges with different road surface damage and traffic conditions. The results show that the IMs depend on both the traffic loading and bridge surface roughness conditions. Under the same traffic flow conditions, the values increase when the road surface damage increases. However, the increases in the IMs vary according to the location of the surface roughness deterioration in both of the target bridges. [ABSTRACT FROM AUTHOR]

Bridge maintenance is a highly intricate task that involves considering a wide range of factors in order to achieve optimal decisions that align with multiple objectives, criteria, and the entire lifecycle of the bridge. While physics-informed analysis, such as the finite element method (FEM), can simulate complex and closely coupled scenarios, such as bridge structural analysis, it cannot account for some loosely coupled discrete factors, which could be addressed by ontological reasoning. Therefore, this paper presents a knowledge-driven decision-making framework that combines static knowledge reasoning with dynamic FEM analysis results to support holistic bridge maintenance decisions. One significant contribution of this research is the development of a comprehensive bridge maintenance ontology that incorporates knowledge derived from bridge maintenance standards. Another key contribution is the ability to employ complex runtime rules-based reasoning to tackle intricate bridge maintenance scenarios. To enable automatic knowledge-driven reasoning, an integrated workflow is developed to orchestrate semantic modeling with numerical modeling through a Python-based Web Ontology Language application programming interface (OWL API). This integration facilitates the efficient orchestration of the framework. A case study is presented to demonstrate the potential for the developed framework in assisting with the complex holistic decisions required for bridge maintenance. [ABSTRACT FROM AUTHOR]

To improve shear capacity, as well as reduce on-site casting and steel consumption, a novel Y-shaped perfobond rib (Y-PBL) shear connector with ultra-high-performance concrete (UHPC) grout was proposed. The shear behavior of the Y-PBL shear connector was investigated by six groups of pushout specimens. Their failure modes, load–slip curves, load–separation curves, strain analysis, and shear transfer mechanisms were discussed. Subsequently, finite-element analysis (FEA) models were established to study the effect of parameters on the shear behavior of the Y-PBL shear connector, as well as to compare the shear capacity contributions with straight-shaped PBL (S-PBL) shear connectors. Analytical models were proposed to predict the shear capacity of the Y-PBL shear connector. The results reveal that the proposed Y-PBL shear connector has superior shear capacity and stiffness. The contribution of the perforating rebar is minor compared with the end-bearing effect of UHPC. The analytical predictions agree well with the experimental and FEA results. This study can be used to guide the design and application of the Y-PBL shear connector in steel-concrete composite bridges. [ABSTRACT FROM AUTHOR]

Seismic intensity measures (IMs) provide a link between the seismic hazard and the dynamic response of structures subjected to earthquake shaking. The spectral acceleration at the first and usually dominant vibration mode, Sa(T1), is a popular choice for building structures. Meanwhile, the IM selection for bridges is non-trivial since they do not typically possess a single dominant mode. Even for ordinary bridges with a dominant mode, the behavior can change significantly in each principal direction through the activation, or yielding, of its different components. This study examines the performance of a novel IM that incorporates ground motion directionality and structure non-linearity in this context: the nnth percentile of all rotation angles of the inelastic spectral displacement, Sdi,RotDnn. This evaluation is carried out within the context of an ordinary bridge structure and is compared with other conventional IMs used in regional risk assessment of bridges. The case study bridge utilized is a highway overcrossing located in California with two spans and a continuous prestressed reinforced concrete box girder deck section. A large ground motion set was selected from the NGA-West2 database, and incremental dynamic analysis was carried out on the structure to assess the IM performance to characterize collapse. The results indicate that Sdi,RotDnn performs very well compared to other IMs for the bridge structure and could be a prudent choice to characterize inelastic response of bridges with several possible mechanisms in different principal directions. Also, using the RotD50 definition, typically used in ground motion models, showed a 17.3% increase in efficiency compared to RotD100 definition typically used in engineering practice. [ABSTRACT FROM AUTHOR]

Suspension bridges, such as stress-ribbon, are among the simplest structural bridge systems and have the lowest structural height. The flexibility of these elegant bridges poses great challenges for designers to minimize their deformability under asymmetrical operational loads. Due to the small initial sag, such load-bearing structures also cause significant tensile forces, which requires them to have large cross-sections and massive anchor foundations. This paper analyzes an innovative suspension steel bridge structure combined with a string and a cable. More attention is paid to asymmetric loading as this is more relevant for suspension structures. The new structure is studied numerically and experimentally. It is established that the string stabilizes the displacements of the bridge under asymmetric loading. The stabilization efficiency is proportional to the value of the pre-tension force of the string. The obtained results reveal the behavior of the structure and enable an evaluation of the accuracy of the numerical results, as well as the applied modeling. In addition, the experimentally obtained results allow the evaluation of more aspects of the behavior of the new bridge, which will be useful in further studies of this type of structures. [ABSTRACT FROM AUTHOR]

Steel bridge designers and erectors primarily rely on approximate methods, such as 1D line girder analyses and 2D grid analyses. For curved or skewed bridges, this can give erroneous indications of the structure's true behaviour. Refined methods of analysis, such as 3D shell modelling, aim to bring a significant change in the practice of bridge engineering. By moving the industry away from simplistic design assumptions, refined analysis methods lead to more accurate, less conservative results, which in turn brings true benefits such as improved structural safety and increased economy. In this paper, several case studies on curved plate girder and tub girder bridges are presented, which cover the full bridge life cycle, from erection of the steel structure and placement of the concrete deck, down to live load analyses using influence surfaces and load rating. The case studies will be modelled with mBrace3D, a dedicated FEA software for curved steel bridges. [ABSTRACT FROM AUTHOR]

The blast resistance of a typical two-lane steel girder highway bridge structural system was modeled using a nonlinear finite-element approach that considered material damage, fracture, and separation. Critical blast scenarios were based on field observations of terrorist attacks on bridges in Iraq, while system failure was defined in terms of practical emergency serviceability criteria used on actual blast-damaged bridges. The blast resistance of various design parameters was assessed, including the number of girders, deck concrete strength, reinforcement ratio, slab thickness, girder and reinforcement yield strength, girder sectional dimensions, and pier column width. The presented approach uniquely quantifies structural system blast resistance in terms of the charge weight that can be applied at different locations until failure. A sensitivity analysis was conducted to determine the most influential design parameters. It was found that system blast capacity was primarily influenced by the number of girders and girder yield strength, while additional significant parameters were deck compressive strength, deck thickness, web stiffener width, and girder depth. Secondary parameters were deck reinforcement ratio, girder flange, and web thickness, while deck reinforcement yield stress was found to be insignificant. Based on the results, recommendations for improving blast resistance are provided. [ABSTRACT FROM AUTHOR]

Single-column bridges are widely used for urban overpasses and highway bridges. Rising overturning incidents have exposed the vulnerability of this type of bridge, which is inherently susceptible to overturning collapse. A typical solution is to provide vertical restrainers at the beam ends. However, the current antioverturning calculation method was incapable of coordinating deformations between bridge components, which may have severe consequences in engineering practice. For example, the Huahu Viaduct, located in Hubei, China, experienced overturning failure even after applying vertical restrainers, which was not anticipated according to the current engineering experience. In this work, we proposed a modified calculation method regarding deformation coordination to predict the ultimate overturning capacity, verified through forensic investigation and numerical analysis, of the Huahu Viaduct. Compared with bridges without restrainers, overturning failures start with the failure of restrainers. Failure mechanisms are analyzed, including critical states and overturning features. Further comparison indicates that the practical method overestimates the ultimate overturning capacity by up to 38%, while the proposed method provides a more effective reference to this problem in engineering practice. [ABSTRACT FROM AUTHOR]

Changes in vehicular loading over time have caused some concrete slab span bridges to rate poorly when considering modern truck weights, which leads to load posting and restrictions that in turn lengthen trucking routes. A potential way to allow heavier vehicles to cross these bridges would be to increase the load rating by utilizing a more accurate live load distribution factor generated from field testing and computational modeling. The focus of this study was to determine the live load distribution factor for two slab span bridges using results from live load testing and plate model analysis. Field testing utilized a suite of instrumentation, and simple isotropic or orthotropic plate models of the slab span bridges were validated with field data to further investigate live load distribution. Field-test estimates of equivalent width computed using displacement data were more precise than those using strain data, but modeling indicated that strain data may better capture the distribution of stresses in the slab. Despite significant visible damage, the field bridge behaved more like an isotropic plate. AASHTO equivalent widths were conservative when compared with those computed from the field results and isotropic model for single-lane truck loading but were similar to each other for multilane loading. However, model results also indicated that the equivalent width depends on the load configuration, such that single-axle loading will be concentrated into a narrower strip compared with tandem loading. In addition, an orthotropic slab will further narrow the equivalent width compared with an isotropic slab, such that AASHTO equivalent widths may no longer be conservative for single-axle loading of a slab so degraded that it may be treated as effectively orthotropic. [ABSTRACT FROM AUTHOR]

This study investigates traffic load as a cause of urban decay and failure on a highway in Nigeria, using Ibadan–Oyo road as a case study. This study identifies road failure as a major city nightmare that affects the well-being of urban dwellers in the study area. The Ibadan–Oyo road is a segment of the major road intersection that connects the southern part of Nigeria with the north. The methodology for this study involves a well-structured questionnaire administered to road users to elicit primary data on the factors and effects of urban decay due to traffic load. A total of 100 Questionnaires were randomly distributed among the road users (vehicular and pedestrians) of the Ibadan–Oyo road. In all, 92 questionnaires were returned. These were analyzed using the Relative Importance Index (R.I.I) and basic statistical tools, to better understand the trend of responses. The results from the study show the factors that enable traffic load and failure include the road as a major route to various parts of the country, not obeying driving laws, poor driving habits, and poor/absence of road pavements. The stress of heavy vehicles on the Ibadan–Oyo road also proves to be a major factor which leads to incessant failure of the road, even after maintenance or reconstruction has been carried out. The failure of this urban infrastructure and the poor road networks leads to many accidents, acute vehicular fuel consumption, waste of time, breakdown of vehicles and road rage. To drastically reduce the impact of infrastructural decay and failure on highways, this study suggests the following: construction of separate routes for trucks and other heavy vehicles, provision of various parks along travel routes for heavy vehicles, and use of a weighing bridge to regulate the range of axle load, replacement of flexible paving with a more rigid design for increased strength and road life span, proper rehabilitation and reconstruction of the failed segment, provision of an alternate railway system to convey heavy goods and also reduce the stress on road transport, in-depth training of vehicle drivers and traffic personnel and lastly, enlargement of the road width. [ABSTRACT FROM AUTHOR]

This paper proposes a mathematical framework for optimal retrofit and recovery strategies of bridge networks. The pre-earthquake and postearthquake management of the highway systems is addressed considering performance objectives based on seismic resilience and life-cycle costs. Structural capacity of vulnerable bridges and traffic performance of the transportation network are investigated accounting for the effects of aftershocks by state-dependent fragility curves informing cumulative damage scenarios. Optimal intervention sequences are identified under uncertainties related to bridge damage levels and mainshock–aftershock sequences based on a biobjective optimization problem aiming to maximize network resilience and minimize costs associated with pre-event retrofit and postrepair restoration activities. [ABSTRACT FROM AUTHOR]

This paper quantified the seismic resilience (SR) of different bridge classes by performing three-dimensional advanced numerical simulations in Opensees. SR was calculated by performing the seismic resilience for recovery investments of bridge (SRRIB) methodology that is based on the quantification of the losses and the repair time. In particular, the probabilistic-based methodology developed by the Pacific Earthquake Engineering Research Center (PEER) was implemented to produce fragility curves by considering the longitudinal displacement of the deck as the reference parameter. The recovery process was modeled using a linear formulation due to the unavailability of information from past earthquakes. SR for the selected bridge classes was calculated in terms of the seismic intensities to be applied for decision-making procedures during pre- and postearthquake assessments. [ABSTRACT FROM AUTHOR]

The intent of this article is to analyse the interconnectedness between urban transformation and eco-heritage value over time in Tianjin from a river-city perspective. The focus is on the Hai River's (海河) contribution to the mechanisms of space and power in imperial, hyper-colonial, and globalising Tianjin. After an analytical excursus of the Haihe's historical-political-economic roles, attention is given to the Haihe as the fulcrum of Tianjin's creation as a spectacle city in present times. The objectives are to elucidate the Tianjin Municipal Government-led urban 'beautification' strategy and analyse the aims and objectives of the 2002 'Comprehensive Reconstruction and Redevelopment Plan of the Haihe's Riversides' while also considering the actual experience of this transformation. The premise of this article is that the Haihe River has helped determine Tianjin's politics of design via heritagisation: the historical processes through which cultural heritage is adapted to strategically promote favourable imagery of the river-city for political management purposes. [ABSTRACT FROM AUTHOR]

Analysing the entire project life cycle is a new trend in sustainability assessment in the construction sector. Research on sustainability issues in the construction sector started with issues related to buildings, while research for other structures such as infrastructure projects and bridges was not originally an integral part of the research. Therefore, the findings, knowledge and practical applications for buildings are more comprehensive than for infrastructure projects. This paper deals with the assessment of the sustainability of bridges throughout their life cycle and emphasises the importance of life cycle analysis of bridges in the early stages of planning and design. The study provides an overview of existing life cycle sustainability assessment (LCSA) methodologies for environmental (Life Cycle Assessment LCA), economic (Life Cycle Cost LCC) and social (Social Life Cycle Assessment S-LCA) aspects. This paper provides a critical overview of the current state of the art in the field of LCSA of bridges. To identify knowledge gaps, a review of the literature on LCSA of bridges, which performs a comparative life cycle analysis of different variants or components of the load-bearing structure of bridges is provided. The main objective of the paper is to provide recommendations for conducting LCSA of bridges and to identify research directions for design criteria for sustainable bridges of the future. [ABSTRACT FROM AUTHOR]

As the primary variable load of bridges, vehicle load is an important parameter for bridge health monitoring. However, traditional Weigh-in-Motion (WIM) systems and the commonly used method of placing sensors on the bridge are challenging to apply in load monitoring for many small and medium-sized bridges. Therefore, this paper proposes a bridge vehicle load identification method based on traffic surveillance video data. Leveraging the surveillance video data on the bridge, without introducing additional hardware devices, the displacement of target points is detected through sub-pixel level image detection algorithms, enabling non-contact measurement of bridge structural response through imaging. A spatiotemporal relationship model of structural displacement, vehicle load, and load distribution is established to solve for vehicle load. Finally, model bridge tests under various loading conditions and engineering practice experiments are conducted to validate the feasibility of the method. The results of the model bridge tests show that the structural displacement measured using traffic video measurement has a deviation of less than 10% compared to the measurements obtained using contact displacement sensors (LVDT), and it can accurately reflect the displacement characteristics of the structure. The results of the field tests demonstrate that the average estimation deviation for heavy vehicle loads ranging from 12 to 18 tons is approximately 18%, meeting the engineering requirements. The proposed method can provide load statistical information for the extensive health monitoring of small and medium-sized bridges and offer a new technical pathway for obtaining bridge load information. [ABSTRACT FROM AUTHOR]

Translation abstract Evaluation and strengthening of existing bridges – historical outlines and findings regarding the Hessian road bridge inventoryTwo short histographical sketches introduce the concepts of refurbishment, condition and load‐bearing capacity assessment between 1700 and 2010 and take a look at the development of the recalculation of existing bridges. Based on project sketches, the hidden safety features of existing road bridges are worked out and procedures for achieving efficient structural bridge strengthening are presented. The focus is on the determination of real object‐specific traffic load models, calibrated structural analyses and additive and non‐destructive strengthening methods. Some critical comments on planning acceleration and the current approval system, together with the demand that bridge construction should be reflected in the common objective of “traffic”, broaden the definition of strengthening holistically. This offers the opportunity to stimulate a discussion about the sensible handling of existing bridges as part of our road infrastructure. [ABSTRACT FROM AUTHOR]

Featured Application: A simple and fast tool is proposed for assessing the rehabilitation needs of bridges and the effectiveness of implementing the seismic isolation of decks to reduce the vulnerability of bridges. The creation of an isolation layer between decks and substructures has turned out to be a viable method for reducing the seismic vulnerability of existing bridges. However, to the Authors' knowledge, a practical approach for a preliminary verification of the effectiveness of this intervention is lacking. The paper introduces a practical tool for a preliminary assessment of the needs of the rehabilitation of the bridge and of the effectiveness of the deck isolation to improve its seismic performance by comparing the demands of the as-built structure and of the piers alone, expressed in terms of equivalent accelerations, to the maximum seismic acceleration allowed to maintain the substructure behavior in the elastic range. A practical implementation of the criterion is illustrated in a parametric study, considering prototypes of simply supported and continuous deck bridges with features common to the bridges of the Italian stock. The results of the study provide some indications about the inherent weaknesses of the examined pier typologies and the positive effect of the dead load of the deck on the effectiveness of deck isolation. [ABSTRACT FROM AUTHOR]

Aiming at the problems of large capacity, narrow transverse width, large excitation, high safety level, and difficulty in accurately grasping the working state of the cable-stayed bridge for the long-span track, this research obtains the structural response data in real time by establishing a health monitoring system. The adaptive filtering method was employed to separate the train load response and the temperature load response. Then, a train load effect analysis method based on the influence line and a temperature load effect analysis method based on the correlation were proposed to assess the operational status of the bridge in real time and objectively. The Chongqing Nanjimen Railway Track Bridge (hereinafter Chongqing Nanjimen track bridge) project was utilized as a case study to demonstrate the application of these methods. The results show that the adaptive filtering method can effectively separate the response of train and temperature loads. The normalized cross-correlation (NCC) results of the measured train load response and the influence line's finite element calculation show a high degree of fit between the measured values and the theory, proving that no significant anomalies are found in the bridge. There is a strong correlation between the ambient temperature difference and the Pearson correlation coefficient of structural response, which indicates that the Chongqing Nanjimen track bridge is currently in normal working condition. [ABSTRACT FROM AUTHOR]

The data quality determines the reliability of big data‐based bridge condition assessments. However, rapidly discerning data conditions and identifying low‐quality data segments pose considerable challenges. This study introduces a transformer‐based autoencoder neural network for rapid data quality assessment in bridge health monitoring. The average Euclidean distance was used to quantify the dispersion of multiple hidden variables, and the overall quality of the multiple data fragments was quantitatively evaluated. Moreover, a method was introduced to calculate the adaptive thresholds based on the Euclidean distance. The application to the acceleration data of a cable‐stayed bridge demonstrates that the proposed method can extract hidden variables from acceleration data segments of length 3000. The network achieves a high compression rate of 1/1500, and the extracted hidden variables retain pertinent information regarding data quality. The proposed approach is data‐driven and exhibits significant advantages in efficiency, accuracy, and user‐friendliness. [ABSTRACT FROM AUTHOR]

Low clearance rail bridges provide vital crossings for freight and passenger trains and are susceptible to frequent strikes from overheight vehicles or equipment. Impact detection systems can help ensure the safety of railroad bridges and their users; such systems streamline monitoring efforts by providing near real‐time strike notifications to rail managers responsible for assessing a bridge after a strike. This paper develops parallel heterogeneous data‐fusion convolutional neural networks (PHD‐CNN) operating on data collected from in‐service rail bridges that improves detection and classification of from overheight vehicles. Convolutional neural networks (CNNs) automatically extract features from multiple data streams from different sensor modalities. The method provides a mechanism to homogenize and fuse disparate data streams for use as inputs to a classifier that distinguishes bridge strikes from passing trains. The study also provides practical implementation guidelines through a framework sensitivity characterization to examine the effects on performance of input data stream type, data set size, and CNN architecture complexity. Optimum networks detect, on average, 95% of bridge strikes with false positive rates less than 2%. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Pseudolaric acids are a family of diterpenoid natural products that exhibit a broad spectrum of biological activities. The main structural feature of their framework is a trans‐fused perhydroazulene bearing a bridged lactone positioned at the junction of the rings. Herein, we have developed a radical cyclization strategy that allows flexible tuning of the cyclization process through diverse silicon substitutions on the substrates. This strategy can assist in constructing a series of skeletons with structural resemblance to pseudolaric acids and expedites the construction of the bridged lactone. Finally, it facilitates the synthesis of the entire skeletal structure of the pseudolaric acid family of natural products, excluding the B‐ring functionalization. [ABSTRACT FROM AUTHOR]

In recent years, accelerated bridge construction has led to the substantial application of precast post-tensioned segmental (PPS) bridge piers. However, PPS piers are not widely used in high-seismicity regions due to their low energy-dissipation capacity (EDC). To address this deficiency, a series of shape memory alloy (SMA)–concrete composite PPS piers were examined in this work. Non-linear static and dynamic analyses were performed on experimentally validated finite-element models of the SMA–concrete composite piers and the results were compared with those of piers without SMA bars. It was found that the length, area and post-tensioning ratio of the SMA bars affected the EDC of the piers, and an optimal design of the bars is required to reach the highest EDC possible. The effects of SMA bars on the frequency response functions of piers were investigated for the first time in this study and it was found that, unlike the piers without SMA bars, sub-harmonics and super-harmonics were not seen in the responses of the SMA–concrete composite piers, mainly the drift responses. Furthermore, the SMA–concrete composite piers experienced a significant reduction in drift responses compared with piers without SMA bars. [ABSTRACT FROM AUTHOR]

This study addresses the limitations of existing indirect bridge damage identification methods that are based on the vehicle–bridge coupled vibration theory of highway bridges. To overcome these shortcomings, we propose an extended approach that incorporates various types of deep-learning models with vehicle–bridge coupled vibration responses. The proposed method is demonstrated using a three-span continuous beam bridge as a case study. First, a vehicle and bridge analysis model is established, and bridge damage is simulated using unit stiffness reduction, considering different damage scenarios. Next, to account for road roughness randomness, vehicle–bridge coupling vibration analysis is performed under various road roughness conditions, yielding the vertical acceleration vibration signal of the vehicle. Subsequently, we employ an end-to-end damage recognition method, utilizing the vehicle acceleration response as the network input, to construct two types of deep-learning models: one-dimensional convolutional neural network (1D-CNN) and convolutional long short-term memory neural network (CNN-LSTM). The recognition performance of both models is compared and analyzed. Taking Zhengzhou Taohuayu Self-Anchored Suspension Bridge in China as an example, this study delves into the capability of bridge damage identification using deep learning. The results demonstrate that the one-dimensional convolutional neural network achieves excellent recognition performance in terms of both damage location and severity. [ABSTRACT FROM AUTHOR]

This study presents the structural damage classification of a large-scale bridge, considering several damage scenarios using One dimensional convolutional neural network (1D-CNN). Measurements obtained from the Z24 bridge in Switzerland during the short-term progressive damage tests are used for this study. Acceleration responses at 291 sensor locations are measured under forced and ambient excitations. This study considers only the measurements under ambient excitations, which has the advantage over forced excitation of not required to measure the excitations. Furthermore, to reduce the overall cost of monitoring the structure, this study aims to use fewer sensor measurements. Out of 291 sensors, only three measurements are used in this study. Each measurement contains 65,536 samples collected at a sampling frequency of 100 Hz. The measurements from three sensors are processed into shorter lengths of 150 data points, each with a 50% overlap. The processed data are inputted to the proposed 1D-CNN model. The proposed 1D-CNN consists of two 1D-CNN networks with different kernel sizes to perform better with different abstract features. The flattened outputs from these two networks using the same input are concatenated and fed into a fully connected dense network for damage classification. The labelled outputs are the different damage scenarios introduced in the progressive damage tests. The performance of the proposed approach is measured in terms of accuracy supported by a confusion matrix. The performance is measured for three cases. The result indicates that better performance is obtained compared to a previous study with the fused features as input to the deep learning models, although fewer sensors are used. Practical Applications: The findings from this study demonstrated that a good damage classification could be achieved using fewer sensor measurements from a large-scale bridge. The Z24 bridge benchmark data are used as an example in this study. Several damage scenarios were considered during the progressive damage test, and all tests were performed under ambient and forced excitation conditions. A multi-headed, one-dimensional convolutional neural network is proposed to classify the damages using the ambient condition data set. The performance is compared with an existing study using the same data set, but the data pre-processing techniques and model are improved. Three cases are defined by varying the size and length of the available time-series data. The proposed model has obtained better damage classification results for all the cases than an existing study. The advantage of the study is that the damage classification is performed using data obtained from a real large-scale structure under ambient conditions, eliminating the need for external force excitation. The proposed method could also be used for condition monitoring and safety evaluation of aerospace and mechanical structures. [ABSTRACT FROM AUTHOR]

The probabilistic seismic demand model (PSDM) is essential to identify the seismic demand of the highway bridge during and after an earthquake. This paper aims to review the probabilistic seismic demand estimation and modeling methodology options associated with the procedure, analytical analysis, and mathematical framework for a highway bridge. As a result of the review, different techniques with features, applications, and limitations on highway bridges are reviewed and presented. A review has investigated the current PSDM and provides a comprehensive summary with formulas, tables, figures, and frameworks. PSDM steps are constructed and introduced to how scholars use them. Besides, analytical methods are the best choice for investigating the PSDA and PSDM for critical bridge components when damage data is insufficient. They are determined to predict each component's seismic response for a given deterministic or random variable. This work helps and motivates the decision-makers and stakeholders to extend the application of the PSDM methodology option for a more informed decision. [ABSTRACT FROM AUTHOR]

Based on construction project data provided by the Connecticut Department of Transportation (CTDOT), this investigation provides an overview of transportation project delivery impactors during the COVID-19 pandemic. Some 205 CTDOT projects are the basis of this comparison study. Of the total number of projects reviewed, 95 were completed before COVID-19 government health guidelines were issued, and 110 were under construction during COVID-19. The two data sets permitted a comparison of the pandemic's effect against prepandemic work. The total value of the projects studied was approximately $2.2 billion over the two distinct periods—one before the emergence of the pandemic and the other during the pandemic. The preCOVID era saw $1 billion worth of work completed, while during the pandemic, an additional $1.2 billion worth of work was carried out. The study demonstrates the pandemic's impact based on 13 factors: schedule, material supply, environmental, weather, extra work, site restrictions, noncompliance/rending notices, surrounding residents, coordination with utilities, design/redesign, quality control, contractor's quality of work, and no major risks/issues. Material supply and schedule were the two major study factors demonstrating pandemic impact. Because of social distancing guidelines, many construction sites had to reduce their workforce, leading to site-wise labor shortages. The projects of the study were separated into eight different types: safety improvements, traffic signal, roadway, bridge rehabilitation, bridge replacement, highway signage, facility renovation, and train station rehabilitation. Out of these categories, train station rehabilitation projects faced the greatest disruption in their material supply chain compared to the other types of projects. [ABSTRACT FROM AUTHOR]

Concrete beams (girders) prestressed with steel cables are widely used in highway bridges. The prestressed steel cables are prone to area loss due to corrosion. The high stress level and deteriorated bond due to corrosion further risks the structural integrity of these beams. Therefore, corrosion-resistant fiber-reinforced polymer (FRP) reinforcement has been investigated as a substitute for prestressed steel in pretensioned concrete beams. While generating data on such members, especially at a large scale, is a slow and costly affair, validated finite-element models (FEMs) can be leveraged to accelerate the process. This paper presents an FEM strategy for carbon fiber–reinforced polymer (CFRP) prestressed beams that is convenient yet sufficiently accurate. A series of AASHTO Type-I beams with a composite deck were previously tested by the authors and the data from those tests were used to validate the developed FEM approach. Thereafter, a parametric study was conducted using the developed FEM, and the results were used to investigate the behavior of such pretensioned concrete beams beyond the scope of the experimental work. The investigated parameters included prestress ratio, modulus, and reinforcement ratio of the prestressing CFRP reinforcement, and the properties of the concrete and the composite deck. The influence of these parameters on the cracking load, precracking and postcracking stiffnesses, flexural capacity, and maximum deflection of the beam was examined. The results indicate that the prestress ratio influences the cracking load and deflection in CFRP-prestressed beams, with FRP properties affecting postcracking behavior and failure modes. The tensile strength and rupture strain of FRP, respectively, affect the bending capacity and deflection, while the concrete properties have a minor impact on the beam behavior. [ABSTRACT FROM AUTHOR]

The ability of structural health monitoring (SHM) systems to detect defects and damage in existing structures is currently a key issue in the life-cycle management of civil infrastructure. In this respect, the use of dynamic identification to detect the loss of prestress load, grouting defects, cracking, and corrosion in post-tensioned concrete (PC) bridges is receiving special interest as an attractive tool that may drive predictive maintenance for disaster risk mitigation, motivating widespread implementation of SHM systems in engineering practice. In this study, an experimental program on reduced-scale PC beams representative of typical girder bridge decks, at the Department of Structures for Engineering and Architecture, University of Naples Federico II, is presented. The specimens were characterized by different prestressing load levels, grout injection conditions of post-tensioning ducts, and strand rupture during testing. Operational modal analysis (OMA) was carried out at multiple steps of each test, which were associated with different damage states of the specimens. OMA results show that both natural frequencies and mode shapes of PC girders are not significantly influenced by slight cracking corresponding to service load levels, while indicating some frequency variations in the case of local strand failure. [ABSTRACT FROM AUTHOR]

This study addresses the absence of a provincial scale database on chloride exposure for bridges, which specifically focuses on Ontario, Canada. Considering the region-based climate and traffic characteristics, a comprehensive database was developed based on chloride exposure prediction models. This database documents chloride exposure information under different Representative Concentration Pathways (RCPs) of greenhouse gas (GHG) emissions for bridge piers and decks across regions and times. This prediction model was validated against experimentally derived chloride profiles from concrete core samples. The database allows for the assessment of spatial and temporal patterns in chloride exposure, which considers the projected climate change conditions. To facilitate data interpretation, this study employs heat maps to transform the extensive provincial database into a visually accessible format. Bridge piers in Southern Ontario have higher surface chloride concentrations than those in Northern Ontario; however, bridge decks in Northern Ontario tend to exhibit higher surface chloride concentrations compared with those in Southern Ontario. Future projections suggest an overall increase in the surface chloride concentrations on bridge piers across most of Ontario under the RCP4.5 and RCP8.5 scenarios, which is largely attributed to increased traffic volume. However, certain southern regions might see a decrease under RCP8.5, which is a direct consequence of climate change. In contrast, surface chloride concentrations on bridge decks are expected to decline, a trend that is driven by diminishing snowfall and increasing traffic volume. In addition, these findings suggest that relying on RCP8.5 could lead to underestimating the climate change impacts compared with RCP4.5. This study highlighted the spatiotemporal patterns in highway bridge chloride exposure in the context of climate change. [ABSTRACT FROM AUTHOR]

The fatigue provisions for bridge design in North America and Europe are highly simplified for the sake of practical implementation, in comparison with the state of the art in understanding of the true fatigue behavior. Historically, one significant simplification in the calibration of damage equivalence factors has been to assume that trucks cross the bridge one at a time, when in reality trucks are known to platoon, and multiple truck presence is not uncommon on longer span structures with higher traffic volumes. While code writers have taken steps more recently to consider multiple presence effects, these efforts have been limited, and a clear understanding of the influence of key design parameters on multiple presence effects has not yet been fully established. Against this background, the present work considers real-time multilane weigh-in-motion (WIM) data and compares fatigue damage from recorded loading events over years to the damage resulting from the same vehicles crossing the bridge individually, to better understand the significance of multiple vehicle presence effects on fatigue damage. For both finite and infinite life fatigue design, the results show that multiple vehicle presence effects can be significant, depending on traffic volume, road configuration, and influence line characteristics. Multiple presence factors are therefore defined, allowing practitioners to consider multiple presence effects appropriately when designing bridges where they may be relevant. [ABSTRACT FROM AUTHOR]

The current design guidelines for concrete barriers have not been updated much since the 1990s despite (1) several experimental, analytical, and computational studies that addressed both the demand and capacity sides of the design problem and (2) substantial increases in the velocity and weight of certain types of trucks specified in the crash testing guidelines that led to significantly higher impact demands than in the previous times. This state-of-the-art paper critically reviews the findings of previous studies and critiques their proposed design models. It highlights the lack of consensus regarding the failure mechanisms that should be considered in the design of concrete barriers and contrasts the results of a variety of proposed models with current design guidelines. Based on the review, recommended models for barrier design are proposed to aid in future revisions of the design specifications. Future research directions are also identified and discussed. [ABSTRACT FROM AUTHOR]

This study presents the experimental results on a scaled bridge model with a newly proposed unidirectional rocking isolation bearing system (referred to as Uni‐RIBS) on a shaking table. The bridge model features one superstructure girder and four bearings. The experimental input encompassed a variety of recorded, design, and harmonic ground motions, characterized by differing peak accelerations, with or without vertical components, and time‐scaled attributes. The superstructure girder's mass was altered for two conditions (full and half). The test results validate the rocking mechanism inherent in the Uni‐RIBS and demonstrate the analytical model's accuracy in predicting the system's dynamics, including its negative stiffness, mass‐independent, and energy dissipation characteristics during bearing rotation reversals. Additionally, this study examines the effectiveness of a simplified numerical model in varying complexities for predicting the seismic responses of the bridge model. [ABSTRACT FROM AUTHOR]

Purpose: The work on bridge resilience assessment includes quantitative and qualitative approaches to compare the multiple bridges based on their resilience. But still, the bridge resilience obtained by these assessment approaches is inefficient when prioritising multiple bridges to improve their resilience. Therefore, this study aims to develop a methodology for prioritising the bridges to improve their resilience. Design/methodology/approach: The research methodology follows three sequential phases. In the first phase, criteria importance through intercriteria correlation (CRITIC) technique is used to compute the criteria weights. The criteria considered are age, area, design high flood level, finish road level FRL and resilience index of bridges. While 12 river-crossing bridges maintained by one bridge owner are considered as alternatives. Then, in the second phase, the prioritisation of each bridge is evaluated using five techniques, including technique for order of preference by similarity to ideal solution, VIKOR (in Serbian, Visekriterijumska Optimizacija I Kompromisno Resenje), additive ratio assessment, complex proportional assessment and multi-objective optimisation method by ratio analysis. Finally, in the third phase, the results of all five techniques are integrated using CRITIC and the weighted sum method. Findings: The result of the study enables bridge owners to deal with the particular bridge that requires resilience improvement. The study concluded that it is not enough to consider only the bridge resilience index to improve its resilience. The prioritisation exercise should consider various other criteria that are not preferred during the bridge resilience assessment process. Originality/value: The proposed methodology is a novel framework based on the existing multi-criteria decision-making (MCDM) techniques for contributing knowledge in the domain of bridge resilience management. It can efficiently overcome the pitfall of decision-making when two bridges have the same resilience index score. [ABSTRACT FROM AUTHOR]

During the long-term operation of high-speed railway in our country, affected by various factors such as surrounding environment changes and human engineering activities, large lateral deviation occurs in some line bridge sections, which seriously affects the normal and safe operation of the train and needs to be rectified urgently. Based on the analysis of the principle of bridge rectification by high pressure jet grouting, the theoretical calculation model of bridge rectification is established, and the differential equations of pile deflection, rotation angle, bending moment and shear force under the high pressure jet grouting rectification mode and the analytical formula of pier top displacement are deduced based on the elastic foundation beam theory. Then,by comparing the calculated displacement at the top of the pier with the actual offset of the line,the feasibility of high pressure jet grouting technology for bridge rectification is analyzed, and the rectification effect is verified by typical engineering cases on site. Research shows that the top displacement of pier is related to foundation coefficient and excess pore water pressure generated by high pressure jet grouting; when foundation coefficient and excess pore water pressure take 1 MPa/ m and 80.3 kPa respectively,the top theoretical calculated displacement of pier is 81.8 mm,which is much larger than the actual deviation of ballastless track line of common high speed railway;In the bridge rectification project of a high speed railway Songjiang Grand Bridge,the displacement at the top of the pier calculated by the average value of the measured excess pore water pressure 30.4 kPa 6. 4~31. 0 mm,which is also greater than the maximum deviation 18.2 mm of the line, indicating that the high pressure jet grouting technology is feasible for bridge rectification theoretically;After rectification construction,the bridge and track structure are stable,the line alignment is smooth,and there is no abnormality in the normal speed operation for many years. The theory and practice have proved that the high pressure jet grouting method is a practical and feasible technical measure for bridge rectification. [ABSTRACT FROM AUTHOR]

With the construction of high-speed railway entering a new period, the frequency of railway viaduct stations has increased dramatically. When the pier is high, the space under the viaduct station has a large demand for utilization. Due to the rigidity control, the conventional pier layout is relatively dense, it is likely to form the phenomenon of "pier forest", which is not conducive to space utilization and has poor aesthetics. In order to find a reasonable structural system suitable for high pier viaduct station, this paper takes Dingyuan viaduct station of Hefei-Xinyi High-speed Railway as the engineering background, the existing problems of common structural systems are studied in the design, and a bridge structural system of sparse-piers and semi-integral viaduct station is proposed. This structural system adopts prestressed beam portal pier with cantilever with two inclined columns, which greatly reduces the number and volume of piers, and maintains good mechanical properties. A kind of fixed support which can release horizontal force is innovatively proposed, which improves the overall stiffness of the structure by changing the structural restraint system. Compared with common structural systems, it can greatly improve the utilization efficiency of the space under the bridge, greatly reduce the structure size and top displacement of piers, and has good aesthetics, practicality and structural mechanical performance. It provides a new idea for the bridge structure design of high-speed railway and other rail bridge viaduct stations. [ABSTRACT FROM AUTHOR]

Expansion joints render bridge structures highly vulnerable to damage during strong ground motions. Failures of expansion joints triggered by earthquakes not only jeopardize the post-earthquake serviceability of the bridge but also have a significant impact on the bridge's overall seismic performance. Despite extensive investigations and efforts to integrate these measures into design specifications aimed at mitigating the consequences of relative movements between adjacent bridge spans, major earthquakes have still revealed instances of damage related to expansion joints. On 6 February 2023, strong earthquake sequences occurred in Kahramanmaraş, Turkey, with magnitudes of M7.7 and M7.6. The fault lines and epicenters of these shallow earthquakes were near the city and town centers and caused severe structural damage to buildings and infrastructures. There are approximately 1000 railway and highway bridges in the earthquake-affected region. Although both highway and railway bridges have generally performed well, some bridges experienced structural damage during the Kahramanmaraş earthquakes. A large number of damage on the bridges is due to pounding and opening relative movements in expansion joints. This paper presents a comprehensive seismic evaluation of expansion joint failure mechanisms on bridges without viscous dampers during the 2023 Kahramanmaraş earthquake sequences and an in-depth investigation into the seismic performance of bridge expansion joints equipped with viscous dampers and shock transmission unit devices are implemented utilizing the strong ground motion data collected throughout the earthquake sequences. It can be stated that the near-fault induced significant directivity and fling effects, resulting in notable velocity pulses and permanent tectonic deformations, and that these effects contributed to the failures of expansion joints, viscous damper devices, pot bearings, and shear keys. [ABSTRACT FROM AUTHOR]

Road crashes, although random events, frequently occur on roads. However, certain characteristic infrastructural locations require detailed analysis regarding the frequency of road crashes. This study examines the dynamics of road crashes at characteristic infrastructural locations in Serbia from 2018 to 2022, focusing on bridges, tunnels, railroad crossings, and road work zones. Using data on road crashes from official reports, the analysis includes trends in crash rates, fatalities, injuries, and material damage during the above-mentioned time frame. In addition to the data analysis, 22 experts from the fields of traffic engineering ranked the mentioned characteristic infrastructural locations in terms of road safety. The same questions were asked to six different artificial intelligence software programs. The findings reveal significant variations in crash rates across different infrastructures, with bridges and road work zones having the highest number of crashes. Expert assessment is in line with the analysis of the results, while artificial intelligence gives a completely opposite assessment. [ABSTRACT FROM AUTHOR]

Bridges are crucial transportation infrastructures with significant socioeconomic impacts, necessitating continuous assessment to ensure safe operation. However, the vast number of bridges and the technical and financial challenges of maintaining permanent monitoring systems in every single bridge make the implementation of structural health monitoring (SHM) difficult for authorities. Unsupervised transfer learning, which reuses experimental or numerical data from well-known bridges to detect damage on other bridges with limited monitoring response data, has emerged as a promising solution. This solution can reduce SHM costs while ensuring the safety of bridges with similar characteristics. This paper investigates the limitations, challenges, and opportunities of unsupervised transfer learning via domain adaptation across datasets from various prestressed concrete bridges under distinct operational and environmental conditions. A feature-based transfer learning approach is proposed, where the joint distribution adaptation method is used for domain adaptation. As the main advantage, this study leverages the generalization of SHM for damage detection in prestressed concrete bridges with limited long-term monitoring data. [ABSTRACT FROM AUTHOR]

Bridge authorities have been reticent to integrate structural health monitoring into their bridge management systems, as they do not have the financial and technical resources to collect long-term monitoring data from every bridge. As bridge authorities normally own huge amount of similar bridges, like the pedestrian ones, the ability to transfer knowledge from one or a small group of well-known bridges to help make more effective decisions in new bridges and environments has gained relevance. In that sense, transfer learning, a subfield of machine learning, offers a novel solution to periodically evaluate the structural condition of all pedestrian bridges using long-term monitoring data from one or more pedestrian bridges. In this paper, the applicability of unsupervised transfer learning is firstly shown on data from numerical models and then on data from two similar pedestrian prestressed concrete bridges. Two domain adaptation techniques are used for transfer learning, where a classifier has access to unlabeled training data (source domain) from a reference bridge (or a small set of reference bridges) and unlabeled monitoring test data (target domain) from another bridge, assuming that both domains are from similar but statistically different distributions. This type of mapping is expected to improve the classification accuracy for the target domain compared to a procedure that does not implement domain adaptation, as a result of reducing distributions mismatch between source and target domains. [ABSTRACT FROM AUTHOR]

The steel in reinforced concrete (RC) members that form plastic hinges must possess sufficient strain capacity to dissipate seismic deformation demands. Unfortunately, there is limited information on the seismic strain demands of bridge column plastic hinges. Instead, designers rely on a perception of cyclic strain capacity that is an approximate rule of thumb. A standard methodology needs to be established for quantifying the strain demand on these structural members as a function of the expected seismic hazard. To develop this methodology, 1944 columns were analyzed with nonlinear time-history analyses (NLTHAs) using ground motions from a range of earthquakes. This study evaluates the strain demand on RC bridge columns by defining the relationship between the strain demand and earthquake intensity. The results of the model are defined in terms of the peak tensile strain of the reinforcing bar, ε t . The earthquake intensity with the highest correlation to the ε t was determined to be the elastic spectral displacement at the optimal period ( S de (T opt)), which is defined as 75% of the effective period. The relationship between ε t and S de (T opt) can be used to predict the strain demand for an RC bridge column at a given geographic location. Results are presented as a probability density function (PDF), representing strain demand, compared to a PDF of the column capacity. The intersection of the capacity curve and demand curve represents the maximum acceptable strain given as a function of S de (T opt). This methodology can help understand the demand placed on a structural system given a region's seismicity. [ABSTRACT FROM AUTHOR]

Accurate identification of moving vehicle loads on bridges is one of the challenging tasks in bridge structural health monitoring, but lacks of intensive investigations to merge the heterogeneous data of vision-based vehicle spatiotemporal information (VVSI) and vehicle-induced bridge responses for moving force identification (MFI) in the existing time domain methods (TDM). In this study, a novel MFI method is proposed by integrating instantaneous VVSI and an improved TDM (iTDM). At first, a novel VVSI method combining background subtraction with template matching is presented to accurately track moving vehicles on bridges. With the calibration technique and camera perspective transformation model, the distribution of vehicles (DOV) on bridges is obtained and used as a priori information in the subsequent MFI. Then, the iTDM is developed based on the MFI equation re-formed in the form of instantaneous VVSI instead of the constant speed vehicle crossing bridges assumed in the traditional TDM. Finally, based on the redundant dictionary matrix composed of Haar functions for a moving load, the MFI problem is converted to explore a solution to the atom vectors and then solved by the Tikhonov regularization method. Experimental verifications in laboratory and a comparative study with the existing three methods are conducted to assess the feasibility of the proposed method. The results show that the proposed MFI method outperforms the existing methods and can effectively identify the moving vehicle loads with a higher and acceptable accuracy. It is successful for the proposed method to replace the assumption of constant speed vehicle crossing bridge in the traditional TDM with the instantaneous VVSI in the MFI problem. [ABSTRACT FROM AUTHOR]