Modal Experiment on RC Flat Plate Frame and Identification of Interior Column Damage

2011 ◽  
Vol 243-249 ◽  
pp. 5399-5402
Author(s):  
Fan Zhen Zhang ◽  
Wei Jian Yi
Keyword(s):  
Flat Plate ◽  
Dynamic Testing ◽  
Simulation Analysis ◽  
Fem Simulation ◽  
Frame Structure ◽  
Structural Safety ◽  
Mode Shapes ◽  
Modal Parameters ◽  
Displacement Mode ◽  
Environment Temperature

Damage identification and health monitoring is an important aspect in the evaluation of structural safety recently. This paper presents a modal experiment and analysis of a 2×2 bay (6.128m×6.128m) 1 storey (1.4m) RC flat plate frame structure on rigid foundation. The displacement mode experiments were carried out by hammer-hitting excitation method in the age of frame concrete. The varieties of the modal parameters of the flat plate were obtained by dynamic testing along with the growth of elastic modulus of concrete and change of the environment temperature. it can be used to identify the location and form of the damage. Base on the missing of some specific structure modal shapes and reduction of the frame horizontal stiffness, it can be revealed that the interior slab-column connection cannot transfer the unbalance moment well. Further more, modal parameters of the RC flat plate with the interior column removed had been exhibited and discussed. A 3-D solid finite element models with the interior column fixed/hinged were constructed, they were validated to match the frame natural frequencies and mode shapes. The results demonstrate the effectiveness of modal parameters identification method in estimate the damage of column in RC flat plate frame. Additionally, the dynamic modulus of elastic is obtained by the comparison of experimental test and FEM simulation analysis.

A Global Damage Indicator Based on the Modal Parameters in the FE-Simulation of the Structures

2011 ◽  
Vol 250-253 ◽  
pp. 1105-1108 ◽  
Author(s):  
Sam Young Noh ◽  
Eun Mi Sin
Keyword(s):  
Structural Damage ◽  
Structural Integrity ◽  
Natural Frequencies ◽  
Frame Structure ◽  
Mode Shapes ◽  
Design Stage ◽  
Modal Parameters ◽  
Damage Analysis ◽  
Damage Indicator ◽  
Damage Simulation

The purpose of the study is the development of a tool for the prediction of the structural damage by means of the numerical damage simulation in the design stage. For the evaluation of the structural integrity in the numerical damage analysis, a global damage indicator was defined based on the modal parameters obtained from the tangential equation of motion: a set of natural frequencies and mode shapes. As they are given in a set, it may be difficult to treat them as a damage indicator. In this study a new damage indicator based on the natural frequencies was defined using the contribution factors of the mode shapes under consideration of the external modal energy. A numerical example of a frame structure showed the efficiency of the damage indicator defined in the study.

Effect of Bass Bar Tension on Modal Parameters of a Violin's Top Plate

2015 ◽  
Vol 39 (1) ◽  
pp. 145-149 ◽  
Author(s):  
Ewa B. Skrodzka ◽  
Bogumił B.J. Linde ◽  
Antoni Krupa
Keyword(s):  
Modal Analysis ◽  
Experimental Modal Analysis ◽  
Mode Shapes ◽  
Modal Parameters ◽  
Normal Value ◽  
Modal Damping

Abstract Experimental modal analysis of a violin with three different tensions of a bass bar has been performed. The bass bar tension is the only intentionally introduced modification of the instrument. The aim of the study was to find differences and similarities between top plate modal parameters determined by a bass bar perfectly fitting the shape of the top plate, the bass bar with a tension usually applied by luthiers (normal), and the tension higher than the normal value. In the modal analysis four signature modes are taken into account. Bass bar tension does not change the sequence of mode shapes. Changes in modal damping are insignificant. An increase in bass bar tension causes an increase in modal frequencies A0 and B(1+) and does not change the frequencies of modes CBR and B(1-).

scholarly journals Comparison of Mode Shapes of Carbon-Fiber-Reinforced Plastic Material Considering Carbon Fiber Direction

Crystals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 311
Author(s):  
Chan-Jung Kim
Keyword(s):  
Carbon Fiber ◽  
Modal Analysis ◽  
Dynamic Behavior ◽  
Mode Shapes ◽  
Modal Parameters ◽  
Carbon Fiber Reinforced Plastic ◽  
Fiber Direction ◽  
Fiber Reinforced ◽  
Fiber Reinforced Plastic ◽  
Reinforced Plastic

Previous studies have demonstrated the sensitivity of the dynamic behavior of carbon-fiber-reinforced plastic (CFRP) material over the carbon fiber direction by performing uniaxial excitation tests on a simple specimen. However, the variations in modal parameters (damping coefficient and resonance frequency) over the direction of carbon fiber have been partially explained in previous studies because all modal parameters have only been calculated using the representative summed frequency response function without modal analysis. In this study, the dynamic behavior of CFRP specimens was identified from experimental modal analysis and compared five CFRP specimens (carbon fiber direction: 0°, 30°, 45°, 60°, and 90°) and an isotropic SCS13A specimen using the modal assurance criterion. The first four modes were derived from the SCS13A specimen; they were used as reference modes after verifying with the analysis results from a finite element model. Most of the four mode shapes were found in all CFRP specimens, and the similarity increased when the carbon fiber direction was more than 45°. The anisotropic nature was dominant in three cases of carbon fiber, from 0° to 45°, and the most sensitive case was found in Specimen #3.

Acoustic Emission Testing of Concrete Frame during Pseudo Dynamic Loading

2006 ◽  
Vol 13-14 ◽  
pp. 195-200
Author(s):  
Athanasios Anastasopoulus ◽  
S. Bousias ◽  
A. Tsimogiannis ◽  
T. Toutountzakis
Keyword(s):  
Acoustic Emission ◽  
Dynamic Testing ◽  
Frame Structure ◽  
Scale Model ◽  
Reinforced Concrete Frame ◽  
Energy Rate ◽  
Concrete Frame ◽  
Emission Testing ◽  
Real Size ◽  
Acoustic Emission Testing

Acoustic Emission (AE) monitoring was performed during Pseudo-Dynamic Testing of a torsionally unbalanced, two-storey, one-by-one bay reinforced concrete frame structure. The structure represented a 0.7-scale model of a real-size frame structure designed and detailed according to the standards prevailing in Greece in 60's, without engineered earthquake resistance. Real time monitoring of AE activity versus the complex applied load resulted in semi quantitative damage characterization as well as comparative evaluation of the damage evolution of the different size columns. Evolution of the AE energy rate per channel, as revealed from zonal location, and the energy rate of linearly located sources enabled the identification of damage areas and the forecast of crack locations before cracks were visible with naked eye. In addition to that, the results of post processing evaluation allowed for the verification of the witnessed damaged areas and formed the basis for quantitative assessment of damage criticality.

Analysis of Modal Parameters of Adhesively Bonded Double-Strap Joints by the Modal Strain Energy Method

1993 ◽  
Author(s):  
Mohan D. Rao ◽  
Krishna M. Gorrepati
Keyword(s):  
Strain Energy ◽  
Natural Frequencies ◽  
Structural Parameters ◽  
Flexural Vibration ◽  
Mode Shapes ◽  
Modal Parameters ◽  
Adhesively Bonded ◽  
Modal Strain Energy ◽  
Joint System ◽  
Damping Material

Abstract This paper presents the analysis of modal parameters (natural frequencies, damping ratios and mode shapes) of a simply supported beam with adhesively bonded double-strap joint by the finite-element based Modal Strain Energy (MSE) method using ANSYS 4.4A software. The results obtained by the MSE method are compared with closed form analytical solutions previously obtained by the first author for flexural vibration of the same system. Good agreement has been obtained between the two methods for both the natural frequencies and system loss factors. The effects of structural parameters and material properties of the adhesive on the modal properties of the joint system are also studied which are useful in the design of the joint system for passive vibration and noise control. In order to evaluate the MSE and analytical results, some experiments were conducted using aluminum double-strap joint with 3M ISD112 damping material. The experimental results agreed well with both analytical and MSE results indicating the validity of both analytical and MSE methods. Finally, a comparative study has been conducted using various commercially available damping materials to evaluate their relative merits for use in the design of these joints.

FEM Simulation Analysis of Cross Wedge Rolling Process

2011 ◽  
Vol 381 ◽  
pp. 72-75
Author(s):  
Bin Li
Keyword(s):  
Simulation Analysis ◽  
Three Dimensional ◽  
Fem Simulation ◽  
Rolling Process ◽  
Stress Distributions ◽  
Cross Wedge Rolling ◽  
Forming Process ◽  
Pressure Distributions ◽  
Metal Forming Process ◽  
Rolling Load

This paper investigates the interfacial slip between the forming tool and workpiece in a relatively new metal forming process, cross-wedge rolling. Based on the finite elements method, three-dimensional mechanical model of cross wedge rolling process has been developed. Examples of numerical simulation for strain, stress distributions and rolling load components have been included. The main advantages of the finite element method are: the capability of obtaining detailed solutions of the mechanics in a deforming body, namely, stresses, shapes, strains or contact pressure distributions; and the computer codes, can be used for a large variety of problems by simply changing the input data.

scholarly journals A Multiobjective Perspective to Optimal Sensor Placement by Using a Decomposition-Based Evolutionary Algorithm in Structural Health Monitoring

2020 ◽  
Vol 10 (21) ◽  
pp. 7710
Author(s):  
Tsung-Yueh Lin ◽  
Jin Tao ◽  
Hsin-Haou Huang
Keyword(s):  
Structural Health Monitoring ◽  
Evolutionary Algorithm ◽  
Health Monitoring ◽  
Sensor Placement ◽  
Frame Structure ◽  
Mode Shapes ◽  
Beam Model ◽  
Optimal Sensor Placement ◽  
Modal Assurance Criterion ◽  
Structural Health

The objective of optimal sensor placement in a dynamic system is to obtain a sensor layout that provides as much information as possible for structural health monitoring (SHM). Whereas most studies use only one modal assurance criterion for SHM, this work considers two additional metrics, signal redundancy and noise ratio, combining into three optimization objectives: Linear independence of mode shapes, dynamic information redundancy, and vibration response signal strength. A modified multiobjective evolutionary algorithm was combined with particle swarm optimization to explore the optimal solution sets. In the final determination, a multiobjective decision-making (MODM) strategy based on distance measurement was used to optimize the aforementioned objectives. We applied it to a reduced finite-element beam model of a reference building and compared it with other selection methods. The results indicated that MODM suitably balanced the objective functions and outperformed the compared methods. We further constructed a three-story frame structure for experimentally validating the effectiveness of the proposed algorithm. The results indicated that complete structural modal information can be effectively obtained by applying the MODM approach to identify sensor locations.

scholarly journals Measuring the modal parameters of a cultural heritage tower by using strong-motion signals

ACTA IMEKO ◽  
2018 ◽  
Vol 7 (3) ◽  
pp. 86 ◽  
Author(s):  
Mariella Diaferio ◽  
Dora Foti ◽  
Nicola Ivan Giannoccaro ◽  
Salvador Ivorra Ivorra
Keyword(s):  
Phase Shift ◽  
Environmental Conditions ◽  
Excitation Frequency ◽  
Strong Motion ◽  
Forced Vibrations ◽  
Mode Shapes ◽  
Modal Parameters ◽  
Vibration Modes ◽  
Experimental Campaign ◽  
Different Levels

This paper presents the dynamic experimental campaign carried out on a stocky masonry clock tower situated in the Swabian Castle of Trani (Italy). The main objective of this paper is, after estimating the main frequencies and vibration modes of the considered structure, defining the transmission of vibrations along the height of the tower by varying the forced frequency at the base. At this aim, short acceleration records have been acquired simultaneously in 20 points of the tower at different levels, due to a series of sinusoidal forced vibrations applied at the base by using a pneumatic shaker device specify designed for the tests. The proposed procedure permit to extract for each monitored point the amplitude of the sinusoidal component related to the excitation frequency and the phase shift due to the structure damping. The results of the proposed procedure are compared with the results of a classical operational modal analysis in environmental conditions in order to demonstrate that the short forced tests permit to classify the typology of the structure mode shapes.

Free Vibration of Damaged Beam Structure with a Notch Defect

2012 ◽  
Vol 226-228 ◽  
pp. 44-47 ◽  
Author(s):  
Jiang Yi Chen ◽  
Li Ge Fan ◽  
Dong Chen Qin
Keyword(s):  
Damage Identification ◽  
Delta Function ◽  
Theoretical Background ◽  
Mode Shapes ◽  
Modal Parameters ◽  
Beam Structure ◽  
Arbitrary Boundary ◽  
Numerical Examples ◽  
Elastically Supported ◽  
Universal Expression

In this paper, we derive the universal expression of the modal parameters for a damaged beam under arbitrary boundary conditions. The delta function is first employed to describe a notch damage in the beam and consequently to derive the governing equation for the damaged beam. Second, by virtue of the perturbation method, the eigenvalues and the corresponding mode shapes are obtained for the damaged beam. Finally, numerical examples are given for an elastically supported beam. It is believed that the proposed approach could provide the necessary theoretical background for damage identification in beam structures.

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