Drive-by bridge mode shape identification using novel reference-based component scaling method

This article proposes a novel method, entitled Reference-based Component Scaling (RCS) method, for estimation of bridge mode shapes using vehicle scanning methods. The proposed method uses two instrumented vehicles to measure the accelerations on the bridge. While one vehicle remains stationary on a pre-determined location, the other one travels over the bridge with a constant speed both exciting the bridge and recording its response. The accelerations recorded on both vehicles are then processed using variational mode decomposition method and Hilbert transform to obtain their modal components. Leveraging its comprehensive framework that incorporates modal components derived from both vehicles, the RCS method effectively tackles the primary challenges encountered by vehicle scanning methods. These challenges include: i) shifting and shrinking effects of bridge damping on mode shapes, ii) distortions in modal components due to incomplete elimination of the roughness effect and iii) distortions in modal components caused by acceleration peaks during the vehicle´s transition from a rigid platform to the bridge. To this end, the RCS method addresses adverse effects of bridge damping without a priori knowledge of the modal damping ratios. To assess the accuracy of the proposed method, numerical analyses were carried out on three different bridges with different number of spans and boundary conditions. The effect of crucial parameters such as road roughness, bridge damping, uncertainties in measurements, and existing traffic on the accuracy of the proposed method was investigated. The results of the numerical study show that the RCS method stands alone in providing accurate estimates of mode shapes of bridges that are seated on elastic bearings, that have realistic damping ratios and relatively high road roughness profiles.publishedVersio

Seismic Vulnerability Assessment of a Historic Brick Masonry Building by Fragility Functions

This paper aims at contributing to the seismic vulnerability assessment of a historic brick masonry building constructed in Istanbul by comparison of the derived analytical and empirical fragility functions. For this purpose, Incremental Dynamic Analysis for each ground motion record was initially performed by series of Nonlinear Time History Analyses on the most vulnerable façade of the case study building modelled using Equivalent Frame Method. By scaling the PGA values of the fifteen earthquake records selected from PEER NGA West2 Data Base, it was aimed to observe the structural response corresponding the all limit states from yield point to collapse and identify each PGA causing the structure to reach these limit states. Herein, PGA and Spectral Displacements were considered as the seismic intensity parameters, and the ultimate storey drifts were referred as Engineering Demand Parameter. Both analytical and empirical seismic fragility functions were derived using lognormal probability distribution. Consequently, the obtained analytical fragility curves for vulnerability assessment of the building were compared with the fragility curves derived according to European (RISK-UE), HAZUS and Istanbul Building Taxonomies for the same building classification with the case study building in attempt to investigate the concordance of the results.publishedVersio

Efficacy of vehicle scanning methods in estimating the mode shapes of bridges seated on elastic supports

This study systematically assesses the efficacy of the vehicle scanning methods (VSM) in accurately estimating the mode shapes of bridges seated on elastic supports. Three state-of-the-art VSM methods are employed to obtain the mode shapes of bridges using the vehicle data during its travel. Two of the evaluated methods use a signal decomposition technique to extract the modal components of the bridge from the contact point of the response while the third one relies on the segmentation of the measured signals along the bridge deck and applying an operational modal analysis tool to each segmented signal to estimate the mode shapes. Numerical analyses are conducted on one single- and one two-span bridge, considering smooth and rough road profiles, different vehicle speeds, and presence of lead vehicle. The accuracy of the numerical models used in developing and assessing vehicle scanning models is tested, and the results of the study demonstrate the method using a half-car vehicle model and signal decomposition technique shows robustness against increasing vehicle speeds and road roughness while the method applying the segmentation of the measured signals provides relatively accurate mode shape estimates at the bridge edges at low speed, although the three methods have their limitations. It is also observed that simplified bridge and vehicle models can hide potential challenges that arise from the complexity of actual vehicle and bridge systems. Considering that a significant number of bridges worldwide are built on elastic supports, the practical success of vehicle scanning methods depends on their ability to handle elastic boundary conditions with reliability. Therefore, the article provides valuable insights into the capabilities and limitations of the current vehicle scanning methods, paving the way for further advancements and refinements in these techniques.Peer ReviewedPostprint (published version

TOWARDS THE CREATION OF SYNTHETIC BRIDGE DIGITAL TWINS WHAT-IF SCENARIOS:STUDY CASE AND CALIBRATION

Digital twins are expected to facilitate the digital transformation of the architecture, construction, engineering, management, operation, and conservation industry. One of their main applications in the field of bridge engineering is the possibility of real-time damage detection. To achieve this, advanced anomaly detection algorithms need to be validated to alert bridge operators on the risks related to the detected anomalies. A synthetic data generation framework has been proposed to generate benchmark databases for testing and validation as a cheaper and faster alternative to the collection of real monitoring data. In this paper we present the S101 Bridge, which has been selected as first case study for the generation of the proposed synthetic database. A finite element model of the bridge was developed and calibrated based on the reported natural frequencies and mode shapes of the actual structure available in the literature. The calibration process is described in detail along with the sensitivity analysis of the considered parameters. The results indicate a strong agreement between the first four natural frequencies and mode shapes of the experimental and numerical bridge model. It is concluded that the calibrated model is suitable for the generation of bride digital twins what-if scenarios, which will be of great significance for both practitioners and the research community.<br/

Seismic Vulnerability Assessment of a Historic Brick Masonry Building by Fragility Functions

This paper aims at contributing to the seismic vulnerability assessment of a historic brick masonry building constructed in Istanbul by comparison of the derived analytical and empirical fragility functions. For this purpose, Incremental Dynamic Analysis for each ground motion record was initially performed by series of Nonlinear Time History Analyses on the most vulnerable façade of the case study building modelled using Equivalent Frame Method. By scaling the PGA values of the fifteen earthquake records selected from PEER NGA West2 Data Base, it was aimed to observe the structural response corresponding the all limit states from yield point to collapse and identify each PGA causing the structure to reach these limit states. Herein, PGA and Spectral Displacements were considered as the seismic intensity parameters, and the ultimate storey drifts were referred as Engineering Demand Parameter. Both analytical and empirical seismic fragility functions were derived using lognormal probability distribution. Consequently, the obtained analytical fragility curves for vulnerability assessment of the building were compared with the fragility curves derived according to European (RISK-UE), HAZUS and Istanbul Building Taxonomies for the same building classification with the case study building in attempt to investigate the concordance of the results

Sensorteknologi for kontinuerlig bruovervåking

Sensorteknologi for kontinuerlig bruovervåking, Evaluering av vellykkede prosjekter og beste praksis for sensorteknologi i bruovervåkingMange av bruene i Norge ble bygget på 1960- , 1970- og 1980-tallet, da kunnskapen om betongens bestandighet var begrenset. Dette har resultert i mange bruer som trenger rehabilitering. For å estimere gjenværende levetid og planlegge kostnadseffektivt vedlikehold, er det viktig å ha en god oversikt over konstruksjonens tilstand. Dagens bruforvaltning er hovedsakelig basert på inspeksjoner, som er kostbare og tidkrevende. Kontinuerlig overvåking med sensorer kan forbedre vurderinger og beslutningsprosesser. Rapporten gir en oversikt over prosjekter med sensorteknologi brukt til bruovervåking, og beskriver beste praksis og suksesskriterier

Towards the Creation of Synthetic Bridge Digital Twins What-If Scenarios: Study Case and Calibration

Downloa

Stange Overpass: Finite Element Model Updating of an Unconventional Railway Bridge

Stange Overpass is a three-span railway reinforced concrete bridge on the Dovre line that connects the cities of Oslo and Trondheim in Norway. It was built in 2002 and has been extended by 1,5 meters in each direction in 2004. During the extension operation, the part of the deck that has been extended from the abutments had not been placed on a foundation but, instead, had directly been constructed over the soil mass. Within the context of the Intercity project that has recently been undertaken by the Norwegian Railway Authority (BaneNOR), passenger trains that cross Stange Overpass will be upgraded to high-speed trains. For this, the existing bridge needs to be evaluated for the new train type. This requires a finite element model that correctly and reliably models the dynamic behavior of the bridge under various environmental and loading conditions. Preliminary analysis results show that the most signi ficant parameter that governs the dynamic behavior of the bridge is the load-deformation behavior of the soil that directly supports the ends of the deck that extends outwards from the abutments. The load-deformation behavior of the soil can be expected to be highly sensitive to the environmental conditions and the changes in these conditions from summer to Nordic winter. To provide a reliable estimate of the load-deformation behavior of soil as well as a reliable finite element model, an instrumentation set-up will be installed in the bridge by Oslo Metropolitan University in collaboration with BaneNOR. A new fi nite element model updating algorithm will be developed that can not only estimate the traditional linear parameters but also the non-linear force-deformation relationship of the soil mass that supports the bridge deck. This article provides a summary of the project together with initial results that include sensitivity analysis that has been conducted to quantify the effects of the soil model on the dynamic behavior of the bridge.acceptedVersio

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

Optimal sensor placement for structural parameter identification of bridges with modeling uncertainties

The uncertainties in the numerical models used for the optimal sensor placement (OSP) studies of civil infrastructures, specifically bridges, considerably affect the results. These effects can be more prominent if the modeling uncertainties are of a kind that significantly alters the mode shapes of the structure, such as the boundary conditions of the model. Yet, these effects on the results of OSP analysis remain unexplored, and there are no available methodologies to address all types of model uncertainties in OSP for civil infrastructures. This research presents a new framework to determine the optimal sensor locations to identify the modal properties of bridges under severe modeling uncertainties and its application on a railway bridge. The framework includes finite element model generation and a sensitivity study to select the most influential parameters that change the dynamic response of the bridge. The selected parameters are used in Monte Carlo simulations, and the results enable quantifying the relative amount of information presented at the candidate sensor locations. This information is combined with the spatial position of the candidate sensor locations, and a hierarchical clustering algorithm is used to obtain the optimal sensor locations and the number of sensors. In addition, the OSP analysis is carried out using the Effective Independence method to contribute to the state-of-the-art literature that investigates the uncertainties in OSP for civil infrastructures and uses this method.Peer ReviewedObjectius de Desenvolupament Sostenible::9 - Indústria, Innovació i InfraestructuraObjectius de Desenvolupament Sostenible::9 - Indústria, Innovació i Infraestructura::9.1 - Desenvolupar infraestructures fiables, sostenibles, resilients i de qualitat, incloent infraestructures regionals i transfrontereres, per tal de donar suport al desenvolupament econòmic i al benestar humà, amb especial atenció a l’accés assequible i equitatiu per a totes les personesPostprint (author's final draft