bluuebunny/crossref_metadata_2025_split huggingface dataset:
Application of empirical green function method for synthesis of response spectrum compatible time histories
Authors: Ji H Y , Lee S J , Kim J H 
Published: June 2024

Abstract
In recent seismic design codes, accelerograms recorded in areas with similar conditions to the target site are required for seismic analysis. When there are no available recorded ground motions of sufficiently large intensities, small intensity ground motions need to be appropriately amplified. In this study, the Empirical Green’s Functions (EGF) method by finite earthquake fault modeling was used for this purpose. The high frequency filter according to the distance between earthquake source to site was applied. The regression analysis of spectral acceleration amplifications by magnitude and hypocentral distance was performed. Finally, the methodology to determine an optimum condition for converting the recorded accelerogram into ground motion time histories compatible with the Design Response Spectrum (DRS) was suggested.
Development of an earthquake simulator for soft soils: Multidirectional Shear Testing Device
Authors: Chao C , Broere W , Jommi C 
Published: June 2024

Abstract
Testing soils for earthquake and dynamic loads requires advanced equipment able to assess the effects of hydromechanical coupling on the soil response. The majority of laboratory element tests are either “slow tests”, which intend to approach drained conditions throughout the soil sample in order to obtain reliable pore water pressure measurements, or “fast undrained tests”, where flow is prevented by closing the drainage lines. However, many natural loads, including earthquakes, impose a wide range of high loading frequencies, typically triggering a partially drained response in the field. Although the rate effect plays an important role in soil behaviour, its investigation is hindered by the limitations of existing equipment. In addition, the ability to apply multidirectional loading to soil elements in the laboratory is important to fully understand the soil response under earthquakes. Currently, multidirectional simple shear devices are used to study the soil behaviour under earthquake loadings. Nevertheless, many shear devices suffer from stresses and strains non-uniformities, which could potentially mislead data interpretation and constitutive models development. This paper presents an innovative multidirectional shear device developed in the section of Geoengineering at TU Delft, which can apply higher loading frequencies compared to previous equipment and a wider variety of multidirectional cyclic loading patterns. The apparatus is equipped with advanced sensors, also developed at TU Delft, to capture the local response of specimens. The sensors are installed to reduce a priori assumptions on the soil response, better interpret the element experimental results and further investigate the rate effect of applied loading. Preliminary performance test results are provided to illustrate the complex load conditions which can be achieved.
Bidirectional Real-Time Hybrid Test on a Steel Column Virtually Connected to a Reinforced Concrete Substructure
Authors: Bodnar B. , Titirla M. , Gatuingt F. , Ragueneau F. , Larbi W. , Deü J.-F. 
Published: June 2024

Abstract
This paper uses a hyper-reduced order model (HROM) to perform bidirectional Hardware-in-the-Loop (HiL) real-time hybrid tests on a steel column virtually connected to a two-story reinforced concrete (RC) substructure under earthquake conditions. Two hydraulic dynamic actuators apply the horizontal displacements at the top of the specimen. Nonlinear multi-fiber beam elements are used to model the numerical substructure. The computational cost of the finite element (FEM) analysis is reduced using a Proper Orthogonal Decomposition (POD) Unassembled Discrete Empirical Interpolation Method (UDEIM) with a non-iterative α-Operator Splitting (α-OS) time integration scheme. Data acquisition is carried out using a Linux® real-time (RT) target, while the dynamic analysis is performed on a Windows® host computer running custom procedures implemented in MATLAB® software. A LABVIEW® interface connects both systems via a lossless stream network. Results on the present case study show that: (1) using a HROM can accelerate costly nonlinear dynamic analyses so that they can be run above the sampling period of the ground motion during hybrid tests, and (2) using lossless stream networks calling a MATLAB® kernel efficiently combines the high data acquisition speed of RT targets (i.e., 10 µs per sample) with the computing power of host computers since the data exchange is quasi-instantaneous.
Robust adaptive compensation of force-based RTHS testing with uncertain compliance spring and force measurement noise
Authors: Araya Diego , Fermandois Gastón 
Published: June 2024

Abstract
This study proposes a force-based real-time hybrid simulation (RTHS) framework with robust compliance-based adaptive compensation. Adding a compliance spring between the loading actuator and a rigid specimen is an alternative to measure restoring forces through load cells with significant noise. But, we considered compliance spring and load cell properties to be uncertainties. Robust adaptive model-based compensation will be employed to overcome force-tracking errors between substructures. The proposed methodology will be verified in a virtual RTHS environment, where parametric studies will be considered to check the system’s robustness over uncertain compliance and specimen properties.
A territorial scale analysis based on a map-oriented database for the out-of-plane seismic behaviour of masonry structures
Authors: Yu Chenjie , Toshniwal Shubham , Meijers Sander 
Published: June 2024

Abstract
Since 1986, earthquakes have occurred in East Groningen, but most buildings made of unreinforced masonry have not been designed for earthquakes, which must now withstand magnitude 4 earthquakes. This has created an urgent need to assess large amounts of buildings in a fast but reliable manner.
The out-of-plane behaviour is important for seismic assessments of unreinforced masonry buildings. Although the most accurate analysis method to determine the out-of-plane response of such walls is non-linear time-history analysis (NLTH), non-linear kinematic analysis (NLKA) provides a simple, fast but still reliable solution due to the computational difficulties of NLTH for structures constructed of unreinforced masonry.
In this paper, the out-of-plane behaviours of masonry structures are up-scaled from a component scale to a provincial scale in a multi-scale manner. A map-oriented database is established to describe both local behaviours of walls and global behaviours of a province. The out-of-plane assessment by non-linear kinematic analysis (NLKA) is automated via the database without further calculations after the static analysis. The database provides a solid guidance to determine which detailed assessment methods will be adopted with limited data before a FEM model is built.
A novel approach for analyzing the dynamic properties of trees with fractal sympodial branching architecture: a group tree modeling
Authors: Loong Cheng Ning , Dimitrakopoulos Elias G. 
Published: June 2024

Abstract
It is remarkable that trees with high slenderness ratios are able to survive regular strong wind events. This phenomenon is motivating the exploration of the inherent vibration mitigation mechanisms of trees. This study examines the role of trees’ hierarchical branching architecture on their modal properties. Its particular focus is on the modal frequencies and mode shapes of sympodial trees. This study idealizes trees as fractal structures with sympodial branching architecture and proposes a new group tree modeling approach to analyze their modal properties. Analytical closed-form solutions are derived to estimate the modal properties of trees. The analysis shows that sympodial trees localize vibrations on higher order branches. Furthermore, the modal properties of trees with a specific fractal level could be self-similar, and repetitive and form recursive relations with that of the previous level. Overall, the results offer a possible explanation of how fractal branching architecture prevents trees from excessive vibration.
Application of dynamics inversion techniques to the force control of electrodynamic actuators used for active vibration absorption
Authors: Ramírez-Senent José , Díaz Iván M , García-Palacios Jaime H , Jiménez Alonso Javier F 
Published: June 2024

Abstract
The active vibration absorber has been successfully used, both in laboratory and actual facilities, to mitigate the human-induced vibrations taking place in lively, low-damping structures such as long-span floors or pedestrian footbridges. Nonetheless, the dynamic behavior of the electrodynamic proof-mass actuators employed for this purpose may negatively affect the overall vibration attenuation features due to the interaction with the motion of the structure under optimization. In this paper, the utilization of dynamic inversion techniques to improve the force control of electrodynamic proof-mass actuators is presented. The main idea behind this approach is to find an approximate inverse model of the actuator dynamics which, upon implementation on a real-time controller, leads to an approximate cancellation of actuator dynamics, making it behave closer to an ideal one. The selected way of proceeding also accounts for the actuator-structure interaction phenomenon. This approach may be employed to improve the performance of any force-based vibration control algorithm. Herein, the dynamic inversion techniques are applied to the well-known Direct Velocity Feedback algorithm which aims at emulating the behavior of a dashpot connected between the control point and the ground in its simplest version. The goodness of the proposed procedure has been assessed both by experimental tests performed over a full-scale composite material pedestrian footbridge existing at the School of Civil Engineering of the Technical University of Madrid. The test results show that the dynamic inversion approach improves the force tracking of the proof-mass actuator to a great extent, therefore yielding better attenuation results that those achieved with the classical Direct Velocity Feedback scheme.
Sliding TLCD for vibration control of base-isolation systems: experimental comparison with traditional TLCD and TMD
Authors: Masnata C , Di Matteo A , Adam C , Pirrotta A 
Published: June 2024

Abstract
In the context of hybrid passive vibration control, the effectiveness of the Tuned Liquid Column Damper (TLCD) for seismic protection of base-isolated (BI) systems has been demonstrated both numerically and experimentally. In contrast to the previous studies on TLCDs, the present study explores the possibility of equipping a BI system with a sliding model of TLCD (STLCD), until now introduced only for the suppression of wind-induced vibrations of fixed-base structures. Specifically, the proposed STLCD consists of a U-shaped tank partially filled with water, mounted on a roller support and connected to the BI system via a spring-dashpot system. The validity of the introduced mathematical model is assessed by means of an extensive shaking table testing campaign at the Laboratory of Experimental Dynamics at the University of Palermo, Italy. For the experimental tests, a small-scale model of a single-degree-of-freedom (SDOF) BI structure with the STLCD is constructed, and the effectiveness of the proposed combined control strategy is experimentally evaluated. Finally, comparisons with traditional TLCDs and TMDs are made and the control efficiency is discussed with emphasis on the reduction of the accelerations of the BI system.
Vibration Control of Wind Turbines through a Novel Reduced Column Section Approach: Numerical Application to the Onshore Wind Turbine in Sassoferrato, Italy
Authors: Rostami Rohollah , Tombari Alessandro 
Published: June 2024

Abstract
The Reduced Column Section (RCS) is a design approach recently proposed by the Authors to convert the transition piece of wind turbines into a passive vibration-control device. Featured with an hourglass shape and high-strength steel, the novel device combines the advantages of several approaches used in seismic engineering, such as the isolation system, the “rocking approach” design as well as the reduced beam section approach. Through proper tuning, the proposed device can be designed to modify the first natural frequency of the wind turbine and to localize the maximum stresses onto the device, protecting the remaining parts of the wind tower and foundation.
In this study, the seismic response of an onshore wind turbine subjected to earthquakes is investigated. The numerical model is developed to reproduce a real onshore wind turbine located in Italy. Operational modal analysis is performed, and the experimental modal frequencies are used to validate the numerical model. Code-compliant spectrum-compatible nonlinear analyses are performed to explore the benefits obtained by adopting the novel RCS approach. Furthermore, an incremental dynamic analysis is conducted to evaluate the dynamic mitigation induced by the proposed RCS device. Results show that the proposed device is able to efficiently mitigate the effective stresses on the wind tower wall by up to 70% compared to the stresses on the existing structure.
Influence of tuned inerter dampers on inelastic seismic performance of building frames
Authors: Sachdeva Rohit , Manohar C S 
Published: June 2024

Abstract
The paper aims to analyse the dynamic behaviour of frames fitted with tuned inerter dampers (TIDs), accounting for various aspects of inelastic frame behaviour, bending-torsion (B-T) coupling, irregularities in elevation, and transient nature of the ground motions. An inerter is a mechanical two-terminal device that creates a force proportional to the relative acceleration between its terminals. It has the potential to produce high dynamic mass while its static mass remains fixed. To gain understanding about its working, an inerter was fabricated and installed in a 3-storey shear-frame model for experimentation and numerical validation. Then, we focus on the behaviour of a 5-storeyed inelastic building frame model fitted with a TID on the ground floor and subject to transient earthquake support motion. The presence of TID is observed to be beneficial in terms of reducing response features such as the ductility demand, hysteretic energy absorbed, and measures of global damage. Finally, a one-story frame, asymmetric in plan, was subjected to two-component earthquake support motion to investigate the influence of the location and number of TIDs on the B-T coupled inelastic behaviour of the frame. The study established the beneficial aspects of incorporating TID(s), while also highlighting the need for further parametric study to design and determine the optimal position of TIDs for achieving best performance.
An approach to define the minimum detectable damage and the alarm thresholds in vibration-based SHM systems
Authors: Kamali Soroosh , Quqa Said , Palermo Antonio , Marzani Alessandro 
Published: June 2024

Abstract
This paper proposes an approach to defining the alarm thresholds for vibration-based structural health monitoring (SHM). The approach uses natural frequencies identified from the acceleration response of the monitored structure and is based on the concept of Minimum Detectable Damage (MDD), namely the smallest damage size in each structural element associated with a given probability of detection (POD) and probability of false alarm (PFA). The approach is demonstrated using natural frequencies computed from finite element models of the healthy and damaged structure, also accounting for temperature fluctuations and measurement noise. The approach first builds a baseline dataset of modal frequencies for a yearly thermal cycle on the healthy structure. Then, different damage conditions are simulated. For each sample of natural frequencies, a Damage Index (DI) is computed as the Mahalanobis distance between the considered sample and the baseline distribution. The alarm threshold is defined as the DI value for a given PFA. Based on the DIs obtained for the damaged structure, the POD is computed for the considered system threshold. This operation is repeated by increasing the damage entity. The MDD is thus defined as the level of damage associated with a desired value of POD. The proposed idea is tested on a steel truss bridge, where the MDD for each element is estimated by considering PFA=5% and POD=95%.
Impact force identification on a ferry dock bridge
Authors: Sibille L , Nord T S , Siedziako B , Fenerci A 
Published: June 2024

Abstract
There is a scarcity of literature on the monitoring of operational loads and structural health of coastal infrastructure assets. In this paper we show the very first estimates of the impact force acting on a ferry quay bridge during ferry berthing based on vibration measurements. The input and state of the structure are estimated by means of a joint input-state estimation algorithm in conjunction with a modally reduced-order finite element model. The estimated and measured accelerations are compared, and a strong agreement is found, even when only a limited number of sensors was used, paving the way for an efficient full-scale monitoring of the structure in the long term.
Assessment of dynamic loading with reverse engineering using vibration measurements
Authors: Xu T , Meijers W , Meijers SJH , Verlinde R 
Published: June 2024

Abstract
This paper presents the application of reverse engineering in assessing the dynamic loading on an industry steel structure. The studied steel structure is subjected to a frequently occurring plug load from the pipeline of a conveying system. This dynamic load leads to significant vibrations of the structure, and it is likely to govern the fatigue analysis. To assess the magnitude of the dynamic load, vibration measurements have been performed. Velocities in the transverse, longitudinal and vertical directions are measured at five points throughout the structure for a continuous period of seven days. A parametric finite element (FE) model of the structure is properly set up such that its eigenfrequencies match the dominant vibration frequencies found in the measurement data. Furthermore, a linear time history (LTH) analysis with impulse loading is carried out, to interpret and reproduce the measured vibrations. Two selected measurements transients, one representative excitation and one randomly selected excitation, are used to validate and fine-tune the FE model to match the vibration responses of the structure. The magnitude and duration of the impulse load is determined such that the response of the analysis model corresponds best to the measurement data in terms of the first and the second peak velocities, as well as the dominant frequencies. Lastly, a statistical analysis is performed to determine the distribution of vibration velocities over the entire measurement period. With the combination of vibration measurements, FEM analysis and statistical analysis, a good estimation of the occurred dynamic load and the amount of stress cycles in 50 years is made for the fatigue analysis of the steel structure.
Assessment of regression variabilities and biases: a demonstration in the context of structural health monitoring.
Authors: Roberts Callum , Avendaño-Valencia Luis David , Cava David Garcia 
Published: June 2024

Abstract
The challenge that is at the forefront of data-driven vibration-based structural health monitoring (VSHM) is the detrimental effect caused by environmental and operational variations (EOVs). Therefore, action must be taken in order to mitigate the effects of the EOVs without affecting the influence of damage. A number of regression-based approaches have been applied in VSHM, using measured environmental and operational parameters to model damage sensitive features (DSFs). In this work, a forward stepwise method is compared with Lasso regression for the purpose of regression model optimisation. The Akaike information criterion (AIC) and the variance of the covariance of the input variables are used to quantitatively assess the quality of the regression models. Additionally, the F-statistic is used to determine which DSFs should or should not be regressed. The results of the analysis showed that the reduced order forward stepwise regression had the lowest AIC and was the most appropriate model despite not having the most stable coefficient matrices. Ultimately, the choice of optimisation method has a significant impact on the quality of future predictions.
Monitoring fatigue crack growth using magnetic stray field measurements
Authors: Meijers P C , Malschaert D H , Veljkovic M 
Published: June 2024

Abstract
To monitor the growth of fatigue cracks in steel specimens, several methods exists. In this paper, the magnetic stray field, which is generated by the magnetisation of the specimen, was measured during loading to investigate how to utilise this data to reliably monitor fatigue crack initiation and growth. Data was collected in a series of fatigue tests on Compact Tension specimens with different force ratios. The evolution of the mean value of the dominant stray field component displayed a sensitivity to stress, plastic deformation and displacement of the specimen. By analysing the stress field induced by the loading, these three causes were distinguished from another. Crack initiation was marked by a large change of the mean magnetic stray field. Moreover, the amplitude of the magnetic stray field components showed a clear peak, at which moment 20% of the life time of the specimen is remaining, indicating that the magnetic stray field might provide a useful method to monitor the evolution of fatigue cracks.
Damage Detection in Beam Structures Based on Curvature Change Estimated from Incomplete Mode Shapes
Authors: Modesti Martina , Reynders Edwin , Lombaert Geert , Palermo Antonio , Gentilini Cristina 
Published: June 2024

Abstract
In this work, a procedure for damage localization and quantification in beam structures is presented. The proposed technique exploits the variations of the curvature between healthy and damaged structures, computed from the flexibility matrix. The flexibility matrix is approximated using the lowest structural frequencies and mode shapes, which can be easily derived on-site from vibration-based monitoring of the structure. Since in real-case scenarios structures can be instrumented only with a limited number of sensors, a procedure based on the expansion of the measured modal components is proposed. The presented technique is verified by testing two beam structures affected by different damages in terms of position and extension.
Uncertainty quantification of damage localization based on a probabilistic convolutional neural network
Authors: Lu HY , Mardanshahi A , Cantero-Chinchilla S , Gryllias K , Chronopoulos D 
Published: June 2024

Abstract
SHM is vital in quantitatively identifying engineered critical structural damage due to its potential economic and security interests. Convolutional Neural Network (CNN) is a popular method used for SHM on damage localization and classification. However, traditional CNN methods have limitations in predicting performance uncertainty and only provide point evaluations without indicating their accuracy. To address this issue, this paper introduces a PCNN framework, which combines a traditional CNN with a probabilistic layer to generate overall confidence intervals (CIs) for prediction results, as well as conditional probability distributions (CPDs) and likelihood for each prediction result. The PCNN method provides a manner to quantify the prediction uncertainty of neural networks and determine the confidence of each prediction. The paper also recommends using Leaky ReLU as the activation function, which retains negative value information. The effectiveness of the PCNN method is illustrated through case studies of carbon fiber-reinforced polymer beams with different layups. The results show that PCNN is effective in giving damage location prediction for CIs, CPDs and likelihood.