scholarly journals Determination of the modal parameters on the thin flat structures

2018 ◽  
Vol 18 ◽  
pp. 91-95 ◽  
Author(s):  
Roman Zajac ◽  
Aleš Prokop ◽  
Kamil Řehák
Keyword(s):  
Modal Parameters ◽  
Flat Structures

Fatigue damage in bending of reinforced concrete frames using non-destructive tests for dynamic strength of the cylinder

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Dragan D. Milašinović ◽  
Aleksandar Landović ◽  
Danica Goleš
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Fatigue Damage ◽  
Cross Section ◽  
Modal Parameters ◽  
The Finite Element Method ◽  
Concrete Frames ◽  
Content Type ◽  
Non Destructive

PurposeThe purpose of this paper is to contribute to the solution of the fatigue damage problem of reinforced concrete frames in bending.Design/methodology/approachThe problem of fatigue damage is formulated based on the rheological–dynamical analogy, including a scalar damage variable to address the reduction of stiffness in strain softening. The modal analysis is used by the finite element method for the determination of modal parameters and resonance stability of the selected frame cross-section. The objectivity of the presented method is verified by numerical examples, predicting the ductility in bending of the frame whose basic mechanical properties were obtained by non-destructive testing systems.FindingsThe modal analysis in the frame of the finite element method is suitable for the determination of modal parameters and resonance stability of the selected frame cross-section. It is recommended that the modulus of elasticity be determined by non-destructive methods, e.g. from the acoustic response.Originality/valueThe paper presents a novel method of solving the ductility in bending taking into account both the creep coefficient and the aging coefficient. The rheological-dynamical analogy (RDA) method uses the resonant method to find material properties. The characterization of the structural damping via the damping ratio is original and effective.

scholarly journals Determination of characteristic Parameters of masonry Structures via Operational Modal Analysis

2019 ◽  
Vol 12 (3) ◽  
Author(s):  
Ali Koçak ◽  
Burak Toydemir ◽  
Melih Bulgur
Keyword(s):  
Modal Analysis ◽  
Operational Modal Analysis ◽  
Physical Models ◽  
Mode Shapes ◽  
Modal Parameters ◽  
Model Parameters ◽  
Masonry Structures ◽  
Characteristic Parameters ◽  
Characteristic Model

Commonly, material and vibration characteristics of masonry structures remain uncertain in the evaluation of existing structures under external loads such as earthquake, heat, wind, etc. In addition, determination of compressive and tensile strength of a masonry walls is not straightforward. However, it is very important to know the characteristic parameters such as eigen values, periods and mode shapes of a structure beforehand in order to create accurate and reliable physical models. Since each historical structure has its own unique wall and bearing characteristics, it is not possible to accept random initial values for the bearing capacity and other parameters of the structure. Besides, conducting vertical and lateral loading experiments is costly and time consuming. An alternative way to determine these parameters that govern the structural behavior is to carry out experimental vibration tests using accelerometers. This method, which is also called as Operational Modal Analysis (OMA), is used to obtain the free and forced vibration response of structures by experimental means and to determine the modal parameters of the structure. OMA is very important for the appropriate use of an analysis method and the model parameters used in the analysis. In this study, two masonry buildings, one of which is historical, are discussed and the modal parameters of buildings are determined experimentally with OMA. Characteristic values obtained from OMA were compared with the three dimensional finite element method by adjusting characteristic model parameters.

Operation Modal Analysis of Pedestrian Bridge in Kroměříž

2020 ◽  
Vol 309 ◽  
pp. 281-287
Author(s):  
Kristína Bezručová ◽  
Radim Nečas ◽  
Jan Koláček
Keyword(s):  
Experimental Determination ◽  
Modal Analysis ◽  
Dynamic Test ◽  
Calculation Model ◽  
Mode Shapes ◽  
Modal Parameters ◽  
Dynamic Tests ◽  
Pedestrian Bridge ◽  
Before And After

The publication outlines the issue of the experimental determination of modal parameters of structures using a method called operational modal analysis. The principle of the method and possible approaches of calculation of modal parameters are presented. An example of the method’s application is the determination of mode shapes and frequencies of the repaired footbridge in Kroměříž where the dynamic test was performed twice – before and after reinforcement of the structure. The results of both dynamic tests and their comparisons with the results of the calculation model performed in the ANSYS environment are presented in this article. Additionally, and integral to this article is a description of the completed footbridge reconstruction.

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