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Most finite element model updating (FEMU) studies on bridges are acceleration-based due to their lower cost and ease of use compared to strain- or displacement-based methods, which entail costly experiments and traffic disruptions. This leads to a scarcity of comprehensive studies incorporating strain measurements. This study employed the strain- and acceleration-based FEMU analyses performed on a more than 50-year-old multi-span concrete highway viaduct. Mid-span strains under heavy vehicles were considered for the strain-based FEMU, and frequencies and mode shapes for the acceleration-based FEMU. The analyses were performed separately for up to three variables, representing Young's modulus adjustment factors for different groups of structural elements. FEMU studies considered residual minimisation and the error-domain model falsification (EDMF) methodology. The residual minimisation utilised four different single-objective optimisations focusing on strains, frequencies, and mode shapes. Strain- and frequency-based FEMU analyses resulted in an approximately 20% increase in the overall superstructure's design stiffness. This study shows the benefits of the intuitive EDMF over residual minimisation for FEMU, where information gained from the strain data, in addition to the acceleration data, manifests more sensible updated variables. EDMF finally resulted in a 25–50% overestimated design stiffness of internal main girders. [ABSTRACT FROM AUTHOR]

Crack propagation in an alumina castable refractory with mullite-zirconia aggregates was investigated in-situ using a wedge splitting test performed inside a laboratory tomograph. Four-dimensional (i.e., 3D space and time) data from digital volume correlation were used to investigate the influence of a realistic crack path on the simulation of the fracture process. A cohesive law was chosen, since toughening mechanisms were present, and calibrated via finite element model updating. When a straight crack path was assumed instead of the experimental crack path, a 10% higher fracture energy and a 35% higher cohesive strength were calibrated. Although the force alone could be used in the minimized cost function, the kinematic information gives valuable insight into the trustworthiness of the geometrical hypotheses assumed in the finite element model. Such framework can be applied to study nonlinear fracture processes for different materials with complex toughening mechanisms such as crack deflection or branching. • A CZM is calibrated via FEMU using force and DVC data from an in-situ wedge splitting test. • The calibration results in differences between experimental and simulated data less than ten times the uncertainty level. • 10% higher fracture energy and 35% higher cohesive strength if a straight crack path is assumed instead of the experimental surface. [ABSTRACT FROM AUTHOR]

This paper aims to evaluate cohesive properties for an alumina refractory with mullite-zirconia aggregates from wedge splitting tests (WST), and to assess their sensitivity to sintering and testing temperature. Five experiments were analyzed of which four were performed at 600∘C. The sought parameters were determined via weighted finite element model updating. The cohesive strength and the fracture energy were successfully calibrated and resulted in simulated data close to their experimental counterparts (i.e., between 4 and 11 times the measurement uncertainty). Increasing the sintering temperature from 1400∘C to 1450∘C enhanced the cohesion between the mullite-zirconia aggregates and the alumina matrix (20 % increase of the fracture energy and of the fracture process zone length). When the WSTs were performed at 600∘C, the cohesive strength was 10 % smaller while the fracture energy was 70 % higher than that at room temperature. [ABSTRACT FROM AUTHOR]

Summary: Accurate finite element (FE) models play an essential role in the health monitoring of operational bridges. Static structural deflections caused by vehicles, which are used in traditional finite element model updating (FEMU) methods, are often procured from field tests, interrupting the traffic and limiting the test loading scenarios. This study proposes a FEMU method that directly applies the massive, multi‐source structural and traffic data in the operation phase to update the FE model, effectively solving the defects above. We use the computer vision‐based vehicle load identification technique to accurately locate and weigh vehicle loads and carry out static simulations in the FE model based on the identified vehicle loads. The proposed FEMU objective function is established using indices including dynamic structural characteristics and vehicle‐induced static structural responses. The static error index in the objective function integrates the curve shape and extrema difference of theoretic and measured static responses. Finally, we deploy a parallel particle swarm optimization (PSO) algorithm to find the global optimal updated FE model. A continuous scale bridge model is employed in the experimental studies with four typical scenarios. Compared to the results from the initial FE model, the updated FE model provides significantly better results both in dynamic and static aspects in all scenarios, and the static error indexes reduce by 75% on average. The proposed method offers a practical approach to deploying the monitoring data for real‐time FEMU, which considers dynamic and static features and provides a basis for damage detection, performance assessment, and management. [ABSTRACT FROM AUTHOR]

Cohesive elements are commonly used to describe crack propagation in heterogeneous materials with toughening mechanisms. This work aims to provide a guideline on how these fracture parameters can be calibrated using notch opening displacements (NODs) measured via digital image correlation and force data from wedge splitting tests (WSTs). Weighted finite element model updating was applied to calibrate material and boundary condition parameters in the same framework. The influence of each parameter on force and NOD data are given together with uncertainties for the calibrated parameters. Numerical results were in very good agreement in terms of splitting force, NOD, displacement and gray level residual fields. It is shown that images obtained during WSTs focusing on the crack path (i.e., hiding the loading region) can be used to drive numerical simulations and obtain cohesive parameters. [ABSTRACT FROM AUTHOR]

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For the use of thermal and environmental barrier coating (T/EBC) with ceramic matrix composites, it is crucial to master the behavior under (extreme) environments representative of the hot section of engine turbines. An experimental setup to simulate such thermal loading has been developed with various diagnostics enabling for kinematic and thermal field measurements, which are used to drive a finite element model and estimate thermomechanical properties such as creep parameters of the coating. [ABSTRACT FROM AUTHOR]

Historic buildings have a high architectural value and their maintenance, repair and rehabilitation require a special approach. This approach is mainly based on the buildings’ performance under non-destructive tests such as operational modal analysis (OMA). Under extreme loads, such as earthquakes, these buildings require representative numerical models to simulate their expected response. In historic buildings, tie rods transfer axial loads and are typically used to balance horizontal trust due to static and dynamic loads associated with seismic actions. It is very important to determine the possibility of exceeding their load-bearing capacity under extreme loads, such as an earthquake. In this context, this paper presents an approach for the analysis of seismic action on the tie rod system in a historic building. The analysis was performed by combining the on-site experimental testing and the finite element model updating (FEMU) of the local models of tie rods and the global model of the structure. It was shown that the combination of analyzing local and global structural models, experimental on-site testing and FEMU is a viable solution for assessment of historic buildings’ load bearing capacity.

Framework of the proposed hierarchical Bayesian FEMU method. [Display omitted] • Effects of operational loads are considered in the hierarchical Bayesian FEMU. • Temperature-stiffness relationship and vehicle load estimation are established. • A two-step MCMC sampling and RSM are proposed to accelerate updating process. • Validated on a long-span arch bridge using two-year monitoring data. • An indicator is defined to assess structural states under operational loads. Excluding the variations of structural dynamic characteristics due to operational loads in finite element model updating (FEMU) is essential for response prediction and structural condition assessment. However, existing FEMU techniques for long-span bridges usually directly use modal parameters in the objective function without considering the effects of various operational loads, resulting in high variations of the updated model. To this end, this paper proposes a hierarchical Bayesian FEMU framework considering the effects of operational loads, including temperature and traffic loads. A linear temperature-elastic modulus relationship and a vehicle load estimation method based on weigh-in-motion (WIM) data are established to quantitatively consider the operational loads' effects on structural dynamic properties. In addition, the identified natural frequencies and measured expansion joint displacements are incorporated into the objective function to update structural static and dynamic properties simultaneously. A two-step Markov Chain Monte Carlo (MCMC) sampling method and a response surface surrogate model are proposed to accelerate the updating process. The proposed method is validated on a long-span arch bridge using two-year monitoring data. The updated model is then used to predict the structural static and dynamic responses by taking into account of operational loads, parameter uncertainties, and modelling errors, and the measured responses generally fall within the predicted 95% confidence interval. Finally, a structural state indicator, which has considered the effects of operational loads on structural properties, is defined to assess the structural condition and successfully detect the pavement replacement process on the bridge. [ABSTRACT FROM AUTHOR]

A methodology is proposed to optimize a specimen shape in a biaxial testing machine for the identification of constitutive laws based on full-field measurements. Within the framework of finite element model updating and integrated digital image correlation, the covariance matrix of the identified material parameters due to acquisition noise is computed, and its minimization is the basis of the proposed shape optimization. Two models are investigated: first, a linear elastic law, and second, an elastoplastic law with linear kinematic hardening. Two optimal fillet radii sets are assessed for the two investigated laws based on the minimization of the identification uncertainty. [ABSTRACT FROM AUTHOR]

Nowadays, virtual manufacturing, digitalisation and simulation predictions are essential for the design and the development of engineering parts and components, as well as companies' productivity. The implemented constitutive model and the accuracy of the determined material parameters influence the reliability of these predictions. It is necessary to calibrate multiple parameters of a complex and robust constitutive model. This is a very time-consuming task and involves high costs when using a classical approach, in which several different homogeneous mechanical experiments are performed. The non-homogeneous mechanical tests can provide a larger variety of mechanical information in just one experiment, reducing the number of required tests for material characterisation. The aim of this work is to numerically design a specimen with an interior notch for a uniaxial loading test that presents strain heterogeneity. The shape of the interior notch is optimised to maximise the strain heterogeneity. The optimisation procedure is guided by a cost function established by several strain heterogeneity indicators. The best specimen shape exhibits numerically uniaxial tension and compression, pure shear and plane strain tension in the plastic region. The identifiability of Swift's hardening law parameters was quantitatively investigated based on the partial derivative of the strain fields with respect to the sought parameters. Results show that the proposed design strategy enables to increase in strain heterogeneity. It is shown that the optimised specimen has significantly better identifiability compared to a tensile specimen with a circular hole. Finally, a comparison between a classical Finite Element Model Updating (FEMU) methodology and a FEMU-based approach that uses a DIC-levelling strategy was conducted in order to inversely identify the Swift hardening law parameters and validate the designed specimen. It was confirmed that the DIC-levelling method finds more accurate results than the classical approach, with the compromise of the computational time. It was also shown that the optimum designed specimen is adequate for inverse identification strategies. • Optimised heterogeneous specimen to test in standard tensile test machine. • Better hardening parameters' identifiability than circular perforated specimen. • The strain states observed in FEA are exhibited in the virtual experiment. • Parameter identification using a DIC-levelled approach is more accurate than the classical. • On the reduction of time, resources and costs in the development of engineering parts. [ABSTRACT FROM AUTHOR]

Historic buildings have a high architectural value and their maintenance, repair and rehabilitation require a special approach. This approach is mainly based on the buildings' performance under non-destructive tests such as operational modal analysis (OMA). Under extreme loads, such as earthquakes, these buildings require representative numerical models to simulate their expected response. In historic buildings, tie rods transfer axial loads and are typically used to balance horizontal trust due to static and dynamic loads associated with seismic actions. It is very important to determine the possibility of exceeding their load-bearing capacity under extreme loads, such as an earthquake. In this context, this paper presents an approach for the analysis of seismic action on the tie rod system in a historic building. The analysis was performed by combining the on-site experimental testing and the finite element model updating (FEMU) of the local models of tie rods and the global model of the structure. It was shown that the combination of analyzing local and global structural models, experimental on-site testing and FEMU is a viable solution for assessment of historic buildings' load bearing capacity. [ABSTRACT FROM AUTHOR]