The health monitoring and damage detection of structures are major scientific issues that the civil engineering discipline, which made great achievements in the 20th century, has bequeathed to the ...21st century. Despite the installation of health monitoring systems in many large structures, implementing damage detection through finite element model updating is often time-consuming or even infeasible due to the size of the model and the presence of numerous uncertain parameters. To address this issue, this paper proposes a substructure-based model updating method. The entire structure is divided into substructures with reduced degrees of freedom, allowing for the simplification of the motion equation by employing only a small number of low-order modes from each substructure. Consequently, the analysis scale of the structure is effectively reduced. The discarded higher modes are compensated by residual modes to ensure the accuracy of structural response and sensitivity. Subsequently, a damage identification program substructure-based model updating is developed, which is applied to component mode synthesis and damage identification for large structures. By precisely detecting damage in critical areas, accurate diagnosis and evaluation of the global structural safety are achieved. The results validate the implementation, computational efficiency, and accuracy of the proposed substructure-based model updating method. This approach shifts the focus from model updating of the entire structure to model updating of substructures, with the aim of fundamentally resolving the technical challenge of accurate damage detection of large and complex structures. Furthermore, it provides theoretical support for the practical application of damage detection in large civil structures.
•Structure is decomposed and condensed into substructures using CMS technique.•Multi-level updating is performed to narrow the damage dimension in each level.•The computational efforts are decreased ...while the identifiability increased.•Kalman filter is adopted to reconstruct the responses of suspicious substructure.•The effectiveness of the method was verified through simulation and laboratory test.
Damage identification through finite element (FE) model updating usually forms an inverse problem. Solving the inverse identification problem for complex civil structures is very challenging since the dimension of potential damage parameters in a complex civil structure is often very large. Aside from enormous computation efforts needed in iterative updating, the ill-condition and non-global identifiability features of the inverse problem probably hinder the realization of model updating based damage identification for large civil structures. Following a divide-and-conquer strategy, a multi-level damage identification method is proposed in this paper. The entire structure is decomposed into several manageable substructures and each substructure is further condensed as a macro element using the component mode synthesis (CMS) technique. The damage identification is performed at two levels: the first is at macro element level to locate the potentially damaged region and the second is over the suspicious substructures to further locate as well as quantify the damage severity. In each level’s identification, the damage searching space over which model updating is performed is notably narrowed down, not only reducing the computation amount but also increasing the damage identifiability. Besides, the Kalman filter-based response reconstruction is performed at the second level to reconstruct the response of the suspicious substructure for exact damage quantification. Numerical studies and laboratory tests are both conducted on a simply supported overhanging steel beam for conceptual verification. The results demonstrate that the proposed multi-level damage identification via response reconstruction does improve the identification accuracy of damage localization and quantization considerably.
This paper offers a structural assessment of the historical Santa Maria Church and its Guesthouse building in Trabzon, Turkey. This process involves non-destructive experimental investigation using ...ambient vibration test and numerical evaluation using finite element method. Finite element model updating procedure was employed for the buildings using experimental data such as dynamic features provided by the ambient vibration test. Time-history analyses were carried out by using initial and final finite element models to draw attention to the effectiveness of the finite element model updating procedure and evaluate the seismic performance. The 1992 Erzincan earthquake ground motion data was used for seismic analysis. The ground motion was exposed to buildings in bidirectional. The maximum displacements and principal stresses are detailed at the end of the analysis using contour diagrams. Result of the analyses, the buildings demonstrated a Limited Damage Performance Level throughout the imposed seismic record according to the Earthquake Risk Management Guide for Historical Structures which is a formal guide.
A model-based fatigue damage estimation framework is proposed for online estimation of fatigue damage, for structural systems by integrating operational vibration measurements in a high-fidelity, ...large-scale, finite element (FE) model and applying a fatigue damage accumulation methodology. To proceed with fatigue predictions, one has to infer the stress response time histories characteristics based on the monitoring information contained in vibration measurements collected from a limited number of sensors attached to a structure. Predictions, like the existence, the location, the time, and the extent of the damage, are possible if one combines the information in the measurements with information obtained from a high-fidelity FE model of the structure. Such a model may be optimized with respect to the data, using state-of-the-art FE model updating techniques. These methods provide much more comprehensive information about the condition of the monitored system than the analysis of raw data. The diagnosed degradation state, along with its identified uncertainties, can be incorporated into robust reliability tools for updating predictions of the residual useful lifetime of structural components and safety against various failure modes taking into account stochastic models of future loading characteristics. Fatigue is estimated using the Palmgren–Miner damage rule, S-N curves, and rainflow cycle counting of the variable amplitude time histories of the stress components. Incorporating a numerical model of the structure in the response estimation procedure, permits stress estimation at unmeasured spots. The proposed method is applied in a steel frame of a real city bus.
In this work, the systematic validation of a deterministic finite element (FE) model updating procedure for damage assessment is presented using a self-developed modular laboratory experiment. A ...fundamental, systematic validation of damage assessment methods is rarely conducted and in many experimental investigations, only one type of defect is introduced at only one position. Often, the damage inserted is irreversible and inspections are only performed visually. Thus, the damage introduced and, with it, the results of the damage assessment method considered are often not entirely analyzed in terms of quantity and quality. To address this shortcoming, a modular steel cantilever beam is designed with nine reversible damage positions and the option to insert different damage scenarios in a controlled manner. The measurement data are made available in open-access form which enables a systematic experimental validation of damage assessment methods. To demonstrate such a systematic validation using the modular laboratory experiment, a deterministic FE model updating procedure previously introduced by the authors is applied and extended. The FE model updating approach uses different parameterized damage distribution functions to update the stiffness properties of the structure considered. The mathematical formulation allows for an updating procedure that is independent of the FE mesh resolution and free of assumptions about the defect location while only needing few design variables. In this work, the FE model updating procedure is based only on eigenfrequency deviations. The results show a precise localization within
±
0.05
m
of the nine different damage positions and a correct relative quantification of the three different damage scenarios considered. With that, first, it is shown that the deterministic FE model updating procedure presented is suitable for precise damage assessment. Second, this work demonstrates that the opportunity to introduce several reversible damage positions and distinctly defined types and severities of damage into the laboratory experiment presented generally enables the systematic experimental validation of damage assessment methods.
An unbalance identification and balancing technique have been presented using a finite element model of the rotor system. Unlike conventional methods of balancing, the proposed approach of balancing ...computes influence coefficients using the system’s finite element (FE) model. Identification of unbalance in a single disc rotor system has served as a demonstration of the method’s applicability. The traditional method of balancing involves the laborious addition of trial weights and vibration measurement during the process of calculating influence coefficients. As the necessary information is derived from the FE model of the rotor system, the suggested method of balancing does not require the addition of trial weights. It is suggested to use an updated FE model of the rotor system in order to compute the vibration data necessary in the calculation of influence coefficients. The finite element model of the rotor system has been updated using the Inverse Eigen Sensitivity Method. In order to find the heavy spot, the unbalance in the rotor disc’s phase angle can be found using the method of unbalance identification. Numerous spin speeds of rotation have been used in the experimental studies of unbalance identification to determine if there is any effect.
The regular cable force detection during the service period is necessary for ensuring the safety and health of the prestressed grid structure. However, because the cable is threaded into the bottom ...chord tube of the grid, the existing cable force detection method cannot be used in the prestressed grid structure with the internal cable layout. A method to indirectly detect the structural cable force using the finite element (FE) model updating technology is proposed in this study, the structural static deflection and modal frequency are taken as characteristics, and the cable force and other structural parameters are used as the updating variables. In addition, a hierarchical objective model updating pattern is proposed to solve the problem that too many updating parameters affect the cable force identification accuracy and efficiency. An actual engineering structure is adopted as a case study, including the identification method verification based on the simulation data and the actual structure cable force evaluation based on the measured data. The research results indicated that it is effective to use the FE model updating technology to detect the cable force of the prestressed grid structure with the internal cable layout, and the accuracy and reliability of cable force identification can be improved by the hierarchical objective model updating pattern.
•Operational modal testing of a group of historical masonry buildings.•Topographic control and ambient vibration tests are used for the control of a structural intervention.•Updated FE model is used ...to control a structural intervention in different stages.•Updated FE model is used to foresee the behaviour of a group of historical buildings after a structural intervention.
This paper presents the dynamic characterization of a group of historical buildings located over the Roman Theatre of Cadiz (Spain), a piece of heritage that has been buried for centuries under the historical town. In 2010, an intervention began in order to excavate it, while respecting the buildings over it. The control of this intervention is being done by means of topographic control points and ambient vibration tests. On the basis of the results obtained from the dynamic tests, a finite element model was updated and subsequently used to check the current works and foresee the final behaviour of the complex. A brief description of the Roman theatre and the works to recover it, the methodology followed to control such works and the results obtained are the main goals of this paper.
In this paper, A high-order response surface method is proposed for finite element model updating of continuous beam bridges. Firstly, based on visual inspection and environmental vibration testing, ...the peak picking (PP) method and random subspace identification (SSI) method are used to identify the dynamic characteristic parameters of the structure. Then, the finite element model of the continuous beam bridge is updated based on the third-order response surface method. It can be concluded that the results of the updated finite element model are in good agreement with the test results, and the maximum error between the calculated and measured frequency is less than 3%, with MAC values greater than 85%. Moreover, the updated finite element model can reflect the current situation of real bridges and serve as the basis for bridge health monitoring, damage detection, and safety assessment.
