Experimental validation of a FRF-based model updating method

2016 ◽  
Vol 24 (8) ◽  
pp. 1570-1583 ◽  
Author(s):  
Fariba Shadan ◽  
Faramarz Khoshnoudian ◽  
Daniel J Inman ◽  
Akbar Esfandiari
Keyword(s):  
Measurement Errors ◽  
Model Updating ◽  
Structural Parameters ◽  
Element Model ◽  
Lumped Mass ◽  
Sensitivity Equation ◽  
Modeling Errors ◽  
Incomplete Measurement ◽  
Aluminum Beam

In this paper, a finite element model updating method using frequency response functions is experimentally validated. The method is a sensitivity-based model updating approach which utilizes a pseudo-linear sensitivity equation. The method is robust against the adverse effects of incomplete measurement, measurement errors and modeling errors. The experimental setup consists of a free-free aluminum beam, where changes are introduced by reducing the stiffness and attaching lumped mass at certain parts of the beam. The method is applied to identify the location and amount of the changes in structural parameters. The results indicate that the location and the size of different level of changes in the structure can be properly identified by the method. In addition, a study is done on the influence of the number of impacts and sensors on the quality of the identified parameters.

scholarly journals Sensitivity Analysis of the Influence of Structural Parameters on Dynamic Behaviour of Highly Redundant Cable-Stayed Bridges

2013 ◽  
Vol 2013 ◽  
pp. 1-11 ◽  
Author(s):  
B. Asgari ◽  
S. A. Osman ◽  
A. Adnan
Keyword(s):  
Sensitivity Analysis ◽  
Finite Element ◽  
Finite Element Model ◽  
Model Updating ◽  
Structural Parameters ◽  
Element Model ◽  
Structural Behavior ◽  
Model Tuning ◽  
The Finite Element Model ◽  
Cable Stayed Bridges

The model tuning through sensitivity analysis is a prominent procedure to assess the structural behavior and dynamic characteristics of cable-stayed bridges. Most of the previous sensitivity-based model tuning methods are automatic iterative processes; however, the results of recent studies show that the most reasonable results are achievable by applying the manual methods to update the analytical model of cable-stayed bridges. This paper presents a model updating algorithm for highly redundant cable-stayed bridges that can be used as an iterative manual procedure. The updating parameters are selected through the sensitivity analysis which helps to better understand the structural behavior of the bridge. The finite element model of Tatara Bridge is considered for the numerical studies. The results of the simulations indicate the efficiency and applicability of the presented manual tuning method for updating the finite element model of cable-stayed bridges. The new aspects regarding effective material and structural parameters and model tuning procedure presented in this paper will be useful for analyzing and model updating of cable-stayed bridges.

Structure Statics Finite Element Model Updating Based on Response Surface Methodology

2011 ◽  
Vol 255-260 ◽  
pp. 1939-1943 ◽  
Author(s):  
Miao Yi Deng ◽  
Guang Hui Li
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Response Surface ◽  
Model Updating ◽  
Structural Parameters ◽  
Optimization Procedure ◽  
Element Model ◽  
Surface Model ◽  
Model Parameters ◽  
Finite Element Model Updating

Employing response surface method, the complicated implicit relationship between bridge structural static-load responses and structural parameters is approximately represented by the simple explicit function. Based on this response surface model (function), the structural finite element model parameters can be easily updated by selected optimization procedure. By a numerical example of a two-span continuous beam, the essential theory and implementation of structural static response surface based finite element model updating are presented in the paper.

Selective Sensitivity for Model Updating With Modal Data

1995 ◽  
Author(s):  
Muzio M. Gola ◽  
Aurelio Somà
Keyword(s):  
Degrees Of Freedom ◽  
Model Updating ◽  
Structural Parameters ◽  
Selection Procedure ◽  
Element Model ◽  
Degree Of Freedom ◽  
Data Set ◽  
Minimum Number ◽  
Selective Sensitivity ◽  
Updating Procedure

Abstract In the present work a criterion for the minimum measured data set (modes and degree of freedom) required for a successful updating is established in the case of the inverse sensitivity method. The finite element model is used as a tool for the pre-analysis in order to plan the modal experiments, the selection of modes and degree of freedom to put into play in the updating procedure are obtained though the evaluation covariance matrix of the estimated parameters. A two stage procedure is proposed, in the first part of the work the modal sensitivity problem is reviewed in order to illustrate a systematic procedure capable of enucleating the set of modes that effectively contributes to the updating procedure. Then the procedure is extended to the determination of the minimum number of degrees of freedom to be measured in relation to a desired upper limit for the standard deviation of the structural parameters which are to be updated. Simple frame structures with different parameter locations are used as examples, the convergence on two parameters maps is used as demonstration of the powerful of the selection procedure to predict the chances of the successful updating.

Application of Bayesian statistical method in sensitivity-based seismic damage identification of structures: Numerical and experimental validation

2018 ◽  
Vol 17 (5) ◽  
pp. 1255-1276 ◽  
Author(s):  
Maryam Vahedi ◽  
Faramarz Khoshnoudian ◽  
Ting Yu Hsu
Keyword(s):  
Statistical Method ◽  
Structural Damage ◽  
Damage Identification ◽  
Model Updating ◽  
Least Square Method ◽  
Element Model ◽  
Least Square ◽  
Detection Methods ◽  
Sensitivity Equation ◽  
Stiffness Reduction

Most of the developed sensitivity-based damage detection methods are based on the application of external excitations which could be prohibitive due to infeasible excitation of all structural degrees of freedom. In this regard, identification of damage properties using seismic structural response would be advantageous. In this research, sensitivity-based finite element model updating method is proposed to identify structural damage by earthquake response in the frequency domain and the transfer function of the structure due to ground excitation. The obtained sensitivity equation is solved by linear least square method through defining constraints on the design variables. Since the attainable measured data are restricted by limits on the instrumentations and preciseness of the measurements and due to the fact that only a few of the lower modes of a structure can generally be determined with confidence, a Bayesian statistical method is utilized to enhance the reliability of the predicted damage properties. The proposed technique is applied to a numerical frame model and an experimental six-story steel structure with various scenarios of story stiffness reduction. The results are indicative of the capability of the proposed method for identification of damage location and severity.

scholarly journals Comparison of different finite element model updates based on experimental onsite testing: the case study of San Giovanni in Macerata

2021 ◽  
Author(s):  
Carlo Baggio ◽  
Valerio Sabbatini ◽  
Silvia Santini ◽  
Claudio Sebastiani
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Model Updating ◽  
Numerical Models ◽  
Dynamic Properties ◽  
Structural Parameters ◽  
Element Model ◽  
Ambient Vibration ◽  
Geotechnical Investigations ◽  
Historic Structures

AbstractUnderstanding the behavior of historic structures that have undergone structural changes, restorations, and damage over time is still a significant challenge for structural engineers, particularly in those countries subject to high seismic risk, such as Italy. The study of built heritage for its prevention and conservation is an active research topic, due to the numerous uncertainties present in historic structures. Finite element modelling has become the most common and accessible method to study the behavior of complex masonry structures, however, the gap between numerical and experimental analysis may lead to erroneous results. Model updating techniques can reduce the discrepancy between the behavior of the numerical models and the testing results. The goal of this work is to illustrate a methodology to integrate the information derived from local, global, and geotechnical investigations into the finite element model of the masonry historical church of San Giovanni in Macerata, considering the Douglas–Reid model updating method. The PRiSMa laboratory of Roma Tre University carried out local investigations such as sonic tomography, video endoscopy and double flat jack tests, along with five ambient vibration tests that were processed through the operational modal analysis to extrapolate the dynamic properties of the building (modal frequency, modal shape vector and modal damping). The combined use of global, local and geotechnical information implemented in the methodology effectively reduced the uncertainties of the model and led the refinement and validation of the most relevant structural parameters.

Pareto Optimal Structural Models and Predictions Consistent With Data and Modal Residuals

2007 ◽  
Author(s):  
Evaggelos Ntotsios ◽  
Konstantinos Christodoulou ◽  
Costas Papadimitriou
Keyword(s):  
Measurement Errors ◽  
Structural Model ◽  
Model Updating ◽  
Optimization Problems ◽  
Structural Models ◽  
Element Model ◽  
Pareto Optimal ◽  
Modal Data ◽  
Multi Objective ◽  
Model Class

A multi-objective identification method for model updating based on modal residuals is proposed. The method results in multiple Pareto optimal structural models that are consistent with the measured modal data, the class of models used to represent the structure and the modal residuals used to judge the closeness between the measured and model predicted modal data. The conventional single-objective weighted modal residuals method for model updating is also used to obtain Pareto optimal structural models by varying the values of the weights. Theoretical and computational issues related to the solution of the multi-objective and single optimization problems are addressed. The model updating methods are compared and their effectiveness is demonstrated using experimental results obtained from a three-story laboratory structure tested at a reference and a mass modified configuration. The variability of the Pareto optimal models and their associated response prediction variability are explored using two structural model classes, a simple 3-DOF model class and a higher fidelity 546-DOF finite element model class. It is shown that the Pareto optimal structural models and the corresponding response predictions may vary considerably. The variability of Pareto optimal structural model is affected by the size of modelling and measurement errors. This variability reduces as the fidelity of the selected model classes increases.

Model structure correction and updating of aeroengine casings using fictitious mass modifications

2005 ◽  
Vol 219 (1) ◽  
pp. 19-30 ◽  
Author(s):  
H Shahverdi ◽  
C Mares ◽  
J E Mottershead
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Model Updating ◽  
Element Model ◽  
Mode Shapes ◽  
Combined Model ◽  
Shell Elements ◽  
Turbine Casing ◽  
The Finite Element Model

In this paper the results of a finite element model updating exercise, carried out on closely axisymmetric aeroengine casings, are presented. The correction of the combustion chamber outer casing (CCOC) model is considered and, after assembly with the turbine casing (TC), the quality of the resulting combined model is investigated. The dynamics of both casings is characterized by pairs of close modes, which may be separated by fictitious point mass modifications. The natural frequencies and mode shapes of the fictitiously modified CCOC are determined from receptances obtained from the CCOC in its original (unmodified) configuration. The modifications are shown to improve the understanding of both the CCOC and the system formed by connecting the CCOC to the TC. A particular problem is revealed when model updating is applied to the CCOC. An analysis of the mode shapes locates a modelling error on an inner shell of the structure but it is found that the finite element model is unable to be parameterized for the correction of two pairs of wrongly ordered predicted modes. This can only be achieved by firstly correcting the ‘structure’ of the model itself. The main error is found to be a geometrical inaccuracy, and, when this is put right, the sequence of the modes is corrected. Model updating is then applied to the thickness of certain shell elements and the CCOC is found to be in excellent agreement with measured data, as is the complete model formed from the two models of the CCOC and the TC together.

scholarly journals Stiffness Modification-Based Bayesian Finite Element Model Updating to Solve Coupling Effect of Structural Parameters: Formulations

2021 ◽  
Vol 11 (22) ◽  
pp. 10615
Author(s):  
Jice Zeng ◽  
Young Hoon Kim
Keyword(s):  
Model Updating ◽  
Coupling Effect ◽  
Structural Parameters ◽  
Linear Optimization ◽  
Hessian Matrix ◽  
Element Model ◽  
Optimization Method ◽  
Finite Element Model Updating ◽  
Damage Estimation ◽  
Objective Functions

The Bayesian model updating approach (BMUA) benefits from identifying the most probable values of structural parameters and providing uncertainty quantification. However, the traditional BMUA is often used to update stiffness only with the assumption of well-known mass, which allows unidentifiable cases induced by the coupling effect of mass and stiffness to be circumvented and may not be optimal for structures experiencing damages in both mass and stiffness. In this paper, the new BMUA tailored to estimating both mass and stiffness is presented by using two measurement states (original and modified systems). A new eigenequation with a stiffness-modified system is formulated to address the coupling effect of mass and stiffness. The posterior function is treated using an asymptotic approximation method, giving the new objective functions with stiffness modification. Analytical formulations of modal parameters and structural parameters are then derived by a linear optimization method. In addition, the covariance matrix of uncertain parameters is determined by the inverse of the Hessian matrix of the objective function. The performance of the proposed BMUA is evaluated through two numerical examples in this study; a probabilistic damage estimation is also implemented. The results show the proposed BMUA is superior to the traditional one in mass and stiffness updating.

scholarly journals Dynamic Analysis of Pantograph-Catenary System considering Ice Coating

2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Yongming Yao ◽  
Ning Zhou ◽  
Guiming Mei ◽  
Weihua Zhang
Keyword(s):  
Arc Discharge ◽  
Element Model ◽  
Normal Operation ◽  
Ice Thickness ◽  
Lumped Mass ◽  
Mass Model ◽  
Current Collection ◽  
Coating Method ◽  
Lumped Mass Model

Ice coating on overhead contact system (OCS) will affect the sliding of pantograph, and arc discharge phenomena will occur between pantograph and catenary, which will threaten the normal operation of train. This paper presents a comprehensive model to analyze the dynamics of icing on pantograph-catenary (PAC) system. The finite element model (FEM) is used for building the catenary, the pantograph is modeled as lumped-mass model, and the ice section of the cable is fan-shaped. The increased density method, uniform load method, and combinatorial material method of icing are used to analyze the icing problem of PAC system. The similarities and differences between the three simulation methods are compared. The influence of the ice thickness on the current collection quality between the pantograph and catenary at the different operating speeds calculated by the three methods is basically the same, which fully illustrates the effectiveness of the simulated ice coating method. In comparison, the combinatorial material method is a more reasonable method for calculating the icing of catenary systems. The research also shows that the influence of icing on the current collection quality of PAC system is different when the train runs at different speeds. Specifically, as the speed of trains increases, the effect of ice thickness on the current collection quality of the PAC system is becoming increasingly apparent.

Computation-Effective Structural Performance Assessment Using Gaussian Process-Based Finite Element Model Updating and Reliability Analysis

2020 ◽  
Vol 20 (10) ◽  
pp. 2042003
Author(s):  
Hans Moravej ◽  
Tommy H. T. Chan ◽  
Andre Jesus ◽  
Khac-Duy Nguyen
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Performance Assessment ◽  
Structural Reliability ◽  
Model Updating ◽  
Structural Parameters ◽  
Element Model ◽  
Structural Performance ◽  
Box Girder ◽  
Girder Bridge

Structural health monitoring data has been widely acknowledged as a significant source for evaluating the performance and health conditions of structures. However, a holistic framework that efficiently incorporates monitored data into structural identification and, in turn, provides a realistic life-cycle performance assessment of structures is yet to be established. There are different sources of uncertainty, such as structural parameters, computer model bias and measurement errors. Neglecting to account for these factors results in unreliable structural identifications, consequent financial losses, and a threat to the safety of structures and human lives. This paper proposes a new framework for structural performance assessment that integrates a comprehensive probabilistic finite element model updating approach, which deals with various structural identification uncertainties and structural reliability analysis. In this framework, Gaussian process surrogate models are replaced with a finite element model and its associate discrepancy function to provide a computationally efficient and all-round uncertainty quantification. Herein, the structural parameters that are most sensitive to measured structural dynamic characteristics are investigated and used to update the numerical model. Sequentially, the updated model is applied to compute the structural capacity with respect to loading demand to evaluate its as-is performance. The proposed framework’s feasibility is investigated and validated on a large lab-scale box girder bridge in two different health states, undamaged and damaged, with the latter state representing changes in structural parameters resulted from overloading actions. The results from the box girder bridge indicate a reduced structural performance evidenced by a significant drop in the structural reliability index and an increased probability of failure in the damaged state. The results also demonstrate that the proposed methodology contributes to more reliable judgment about structural safety, which in turn enables more informed maintenance decisions to be made.

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