scholarly journals Dynamic Characterisation and Finite Element Updating of a RC Stadium Grandstand

Buildings ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 141 ◽  
Author(s):  
Filipe Santos ◽  
Corneliu Cismaşiu ◽  
Ildi Cismaşiu ◽  
Chiara Bedon
Keyword(s):  
Finite Element ◽  
Model Updating ◽  
Three Dimensional ◽  
Modal Testing ◽  
Ambient Vibration ◽  
Fe Model ◽  
Modal Parameter ◽  
Ambient Vibration Tests ◽  
Fe Model Updating ◽  
Output Only

This paper reports on the dynamic characterisation of a Reinforced Concrete (RC) stadium grandstand module for the Sporting Stadium in Lisbon. To this aim, a three-dimensional (3D) Finite-Element (FE) numerical model, implemented according to the technical drawings of the structure, is first presented to provide preliminary estimates of the expected modal characteristics for the examined structural system. Ambient vibration tests are then carried out on the same grandstand, and used to extract the natural frequencies and vibration modes of the system, according to conventional state-of-the-art output-only modal parameter identification techniques. A sensitivity investigation and FE model updating study is hence presented for the grandstand, giving evidence of the major influencing parameters and key input data for the numerical fitting of the experimental modal testing results.

The Application of Bees Algorithm in Finite Element Model Updating

2010 ◽  
Author(s):  
Laleh Fatahi ◽  
Shapour Moradi ◽  
Pejman Razi
Keyword(s):  
Finite Element ◽  
Objective Function ◽  
Model Updating ◽  
Research Work ◽  
Modal Testing ◽  
Bees Algorithm ◽  
Physical Parameters ◽  
Piping System ◽  
Fe Model ◽  
Fe Model Updating

This research work is aimed to investigate the application of bees algorithm (BA) to the finite element (FE) model updating. BA is an evolutionary optimization algorithm that imitates the natural foraging behavior of the honeybees to find the global optimum of an objective function. Here, the weighted squared sum of the error between the measured modal parameters and the FE model predictions is considered as the objective function. To demonstrate the effectiveness of the proposed method, BA is applied on a piping system to update several physical parameters of its FE model. The results obtained from the numerical model are compared with the experimental ones obtained through the modal testing. The results show that BA successfully updates the FE model. Moreover, the performance of this approach is compared with two popular optimization methods; the genetic algorithm (GA) and the particle swarm optimization (PSO). The comparison shows the advantage of BA over GA and its similarity to PSO in terms of accuracy in the presented case study. However, BA reaches to the optimum solution faster than PSO and GA. Therefore, it can be concluded that BA is a robust and accurate optimization method that could be a good candidate for the FE model updating.

A Method for FE Model Updating of Coupled Vibro-Acoustic Systems Using Constrained Optimization

2013 ◽  
Author(s):  
D. V. Nehete ◽  
S. V. Modak ◽  
K. Gupta
Keyword(s):  
Finite Element ◽  
Constrained Optimization ◽  
Model Updating ◽  
Numerical Study ◽  
Element Model ◽  
Rectangular Cavity ◽  
Mode Shapes ◽  
Fe Model ◽  
Structural Dynamic ◽  
Fe Model Updating

Finite element (FE) model updating is now recognized as an effective approach to reduce modeling inaccuracies present in an FE model. FE model updating has been researched and studied well for updating FE models of purely structural dynamic systems. However there exists another class of systems known as vibro-acoustics in which acoustic response is generated in a medium due to the vibration of enclosing structure. Such systems are commonly found in aerospace, automotive and other transportation applications. Vibro-acoustic FE modeling is essential for sound acoustic design of these systems. Vibro-acoustic system, in contrast to purely structural system, has not received sufficient attention from FE model updating perspective and hence forms the topic of present paper. In the present paper, a method for finite element model updating of coupled structural acoustic model, constituted as a problem of constrained optimization, is proposed. An objective function quantifying error in the coupled natural frequencies and mode shapes is minimized to estimate the chosen uncertain parameters of the system. The effectiveness of the proposed method is validated through a numerical study on a 3D rectangular cavity attached to a flexible panel. The material property and the stiffness of joints between the panel and rectangular cavity are used as updating parameters. Robustness of the proposed method under presence of noise is investigated. It is seen that the method is not only able to obtain a close match between FE model and corresponding ‘measured’ vibro-acoustic characteristics but is also able to estimate the correction factors to the updating parameters with reasonable accuracy.

Effects of full-height nonstructural partitions on modal properties of two nominally identical building floors

2009 ◽  
Vol 36 (7) ◽  
pp. 1121-1132 ◽  
Author(s):  
Z. Miskovic ◽  
A. Pavic ◽  
P. Reynolds
Keyword(s):  
Model Updating ◽  
Modal Testing ◽  
The Other ◽  
Fe Model ◽  
Nonstructural Components ◽  
Modal Properties ◽  
Open Plan ◽  
Fe Model Updating ◽  
Updating Procedure ◽  
Full Height

This paper presents a combined experimental and numerical investigation of the modal properties of two full-scale and nominally identical steel–concrete composite floors. The floors were one above the other in the same fully operational multi-storey building. Both floors accommodated open-plan as well as partitioned offices. Multi-input-multi-output (MIMO) modal testing was employed to measure as-built modal properties of both floors. It was found that the two nominally identical floors had different modal characteristics, likely due to the different arrangement of partitions in the floor. It was also found that the measured modes on both floor levels experienced a considerable level of complexity, likely to be caused by nonproportional damping. Finite element (FE) models were developed in ANSYS for both floors using best engineering judgement and their features and properties were then tuned to match the measured counterparts. The tuning was done manually by trial-and-error and then automatically using sensitivity-based FE model updating procedure implemented in the FEMtools software. It was found that the initial and geometrically very detailed FE models, which did not feature any nonstructural components, underestimated the measured natural frequencies by up to a considerable 20%–25%, depending on the floor level. When full-height plasterboard and glass partitions were explicitly modelled as vertical springs connected to the floor and grounded at the other end, the correlation between the experimental and FE results improved considerably.

FE Model Updating for Health Monitoring of Structures and its Experimental Verification by Damage Detection

2006 ◽  
Vol 321-323 ◽  
pp. 268-272 ◽  
Author(s):  
Gwang Hee Heo ◽  
Joon Ryong Jeon ◽  
Chin Ok Lee ◽  
Gui Lee ◽  
Woo Sang Lee
Keyword(s):  
Damage Detection ◽  
Health Monitoring ◽  
Model Updating ◽  
Basic Structure ◽  
Ambient Vibration ◽  
Fe Model ◽  
Error Matrix ◽  
Error Ratio ◽  
Before And After ◽  
Fe Model Updating

This paper presents an effective method of FE model updating for health monitoring of structures by applying ambient vibration. And this method is experimented through damage detection and proved to be valid. Experiment about ambient vibration is performed on cantilever beam, and the dynamic characteristics are analyzed by NExT and ERA. The results of such experiments are compared to those of FE analysis, and this comparison enables us to overcome some errors in experiments and analysis. On the basis of improved results by the comparison, model updating is performed in order to construct a basic structure for health monitoring. For model updating, we employ direct matrix updating method (DMUM) and Error matrix method (EMM) in which ambient vibration is easily applied. The model updating by the methods are again evaluated in terms of error ratio of natural frequency, comparing each result before and after updating. Finally, we perform experiments on damage detection to verify the method of updating presented here, and evaluate its performance by eigen-parameter change method. The evaluation proves that the method of FE model updating using ambient vibration is effective for health monitoring of structure, and some further application of this method is suggested.

Analysis of a damaged 12-storey frame-wall concrete building during the 2010 Haiti earthquake Part I: Dynamic behaviour assessment

2013 ◽  
Vol 40 (8) ◽  
pp. 791-802 ◽  
Author(s):  
Benoit Boulanger ◽  
Charles-Philippe Lamarche ◽  
Jean Proulx ◽  
Patrick Paultre
Keyword(s):  
Finite Element ◽  
Dynamic Behaviour ◽  
Model Updating ◽  
Visual Assessment ◽  
Ambient Vibration ◽  
Mode Shapes ◽  
Vibration Frequencies ◽  
Haiti Earthquake ◽  
Ambient Vibration Tests ◽  
Modelling Assumptions

Despite all the damages encountered during the 2010 Haiti earthquake, the 12-storey reinforced-concrete Digicel building behaved well, sustaining only reparable damages. Visual assessment to characterize the damages sustained and ambient vibration tests (AVT) were carried out to identify the building’s key dynamics properties (natural vibration frequencies, mode shapes, and damping ratios). ETABS was used to generate finite element (FE) models before and after the AVT, to evaluate the capabilities of common modelling assumptions to predict the dynamic behaviour of structures. Nonautomated model updating was carried out to generate a model representing the building’s actual dynamic behaviour in its damaged state. The study showed that the finite element method (FEM) is reliable for predicting the dynamic behaviour of structures, but is very sensitive to the modelling assumptions. The models could predict the vibration frequencies precisely, but an accurate representation of the mode shapes required careful model updating.

scholarly journals Finite Element Modelling and Updating of Welded Thin-Walled Beam

2018 ◽  
Vol 15 (4) ◽  
pp. 5874-5889 ◽  
Author(s):  
M. S. M. Fouzi ◽  
K. M. Jelani ◽  
N. A. Nazri ◽  
Mohd Shahrir Mohd Sani
Keyword(s):  
Finite Element ◽  
Model Updating ◽  
Normal Mode Analysis ◽  
Mode Analysis ◽  
Modal Parameters ◽  
Fe Model ◽  
Fe Modelling ◽  
Welded Structure ◽  
Thin Walled ◽  
Fe Model Updating

This article concentrates on the finite element (FE) modelling approach to model welded thin-walled beam and the adoption of model updating technique to enhance the dynamic characteristic of the FE model. Four different types of element connectors which are RBE2, CBAR, CBEAM and CELAS format are used to construct the FE model of welded structure. Normal mode analysis is performed using finite element analysis (FEA) software, MSC Patran/Nastran to extract the modal parameters (natural frequency and mode shape) of the FE model. The precision of predicted modal parameters obtained from the four models of welded structure are compared with the measured counterparts. The dynamic characteristics of a measured counterpart is obtained through experimental modal analysis (EMA) using impact hammer method with roving accelerometer under free-free boundary conditions. In correlation process, the CBAR model has been selected for updating purposes due to its accuracy in prediction with measured counterparts and contains updating parameters compared to the others. Ahead of the updating process, sensitivity analysis is made to select the most sensitive parameter for updating purpose. Optimization algorithm in MSC Nastran is used in FE model updating process. As a result, the discrepancy between EMA and FEA is managed to be reduced. It shows the percentage of error for updated CBAR model shrinks from 7.85 % to 2.07 % when compared with measured counterpart. Hence, it is found that using FE model updating process provides an efficient and systemic way to perform a feasible FE model in replicating the real structure.

Structural Identification and Numerical Models for Slender Historical Structures

2015 ◽  
pp. 674-703 ◽  
Author(s):  
Dora Foti ◽  
Mariella Diaferio ◽  
Nicola Ivan Giannoccaro ◽  
Salvador Ivorra
Keyword(s):  
Model Updating ◽  
Numerical Models ◽  
Ambient Vibration ◽  
Mode Shapes ◽  
Fe Model ◽  
Detailed Structural Analysis ◽  
Ambient Vibration Tests ◽  
Great Confidence ◽  
Vibration Tests ◽  
The Time Domain

In the present chapter the theoretical basis of different methods developed for the calibration of FEMs are discussed. In general, Model Updating techniques are based on the use of appropriate functions that iteratively update selected physical properties (characteristics of the materials, stiffness of a link, etc.). In this way the correlation between the simulated response and the target value could improve if compared to an initial value. The FE model thus obtained can be used for a detailed structural analysis with a great confidence. The technique described in the first part of the chapter is applied to the evaluation of the structural properties of the tower of the Provincial Administration Building in Bari (Italy).The final purpose is to predict the performance of the tower to different combinations of static and dynamic loads, i.e. earthquakes or other induced vibrations. Ambient vibration tests have been performed on the above mentioned tower with the aim of determining its dynamic response and developing a procedure for modeling this building (Foti et al., 2012a). The Operation Modal Analysis (OMA) has been carried out both in the frequency domain and in the time domain to extract the dominant frequencies and mode shapes of the tower.

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