Analysis of Natural Frequencies of Voided Biaxial Concrete Slabs

2017 ◽  
Vol 738 ◽  
pp. 15-24
Author(s):  
Norbert Jendzelovsky ◽  
Kristina Zabakova Vrablova
Keyword(s):  
Numerical Calculation ◽  
Numerical Methods ◽  
3D Model ◽  
Natural Frequencies ◽  
Hollow Spheres ◽  
Concrete Slabs ◽  
Simply Supported ◽  
Floor Systems ◽  
Permanent Fillers ◽  
Methods Numerical

Voided slabs using voids formed by permanent fillers or removable forms have been used in reinforced concrete floor systems for more than 100 years. In this article we will focus on the natural frequency of voided biaxial slabs system Cobiax. Cobiax void former modules are synthetic hollow spheres or rotational ellipsoids mounted in the relevant spaces between the upper and lower reinforcement. We have analyzed the slabs of different thicknesses with adequate void former modules and spans following the manufacturer's recommendations. All models were considered as simply supported slabs. Natural frequencies calculated using simplified analytical methods have been compared with those obtained by numerical methods. Numerical calculation was done using the 2D elements with reduced properties and using the accurate 3D model of a structure.

Comparison of Natural Frequencies of Hollow Core Slabs

2015 ◽  
Vol 769 ◽  
pp. 225-228 ◽  
Author(s):  
Norbert Jendzelovsky ◽  
Kristina Zabakova Vrablova
Keyword(s):  
Natural Frequencies ◽  
Concrete Slabs ◽  
Hollow Core ◽  
Shell Elements ◽  
Method Of Calculation ◽  
Simply Supported ◽  
Simplified Method ◽  
3D Elements ◽  
Hollow Core Slab ◽  
2D Model

This article is devoted to the calculation of natural frequencies of concrete slabs. Natural frequencies of a solid slab and a hollow core slab have been compared. Solid slab and lightened slab with reduced self-weight and stiffness have been modeled using FEM software ANSYS as 2D model using shell elements. Third model was made from 3D elements as a hollow core slab. Two types of boundary conditions have been considered: a simply supported slab and a clamped slab. The changes in natural frequencies according to aspect ratio of the slab were compared, too. Numerical methods have been compared with simplified method of calculation of natural frequency of slabs, as e.g. an equivalent plate approach; approximation presented by Hearmon and compilation of formulas by Bachmann.

Natural Frequency of Laminated Composite Plates Using a Sinusoidal Theory

2014 ◽  
Vol 709 ◽  
pp. 148-152
Author(s):  
Guo Qing Zhou ◽  
Ji Wang ◽  
Song Xiang
Keyword(s):  
Differential Equations ◽  
Analytical Method ◽  
Deformation Theory ◽  
Natural Frequencies ◽  
Shear Deformation Theory ◽  
Laminated Composite ◽  
Composite Plates ◽  
Laminated Composite Plates ◽  
Simply Supported ◽  
Sinusoidal Shear Deformation Theory

Sinusoidal shear deformation theory is presented to analyze the natural frequencies of simply supported laminated composite plates. The governing differential equations based on sinusoidal theory are solved by a Navier-type analytical method. The present results are compared with the available published results which verify the accuracy of sinusoidal theory.

A semi-analytical three-dimensional free vibration analysis of functionally graded curved panels integrated with piezoelectric layers

2014 ◽  
Vol 21 (4) ◽  
pp. 571-587 ◽  
Author(s):  
Hamid Reza Saeidi Marzangoo ◽  
Mostafa Jalal
Keyword(s):  
Boundary Conditions ◽  
Vibration Analysis ◽  
Natural Frequencies ◽  
Differential Quadrature Method ◽  
Three Dimensional ◽  
Free Vibration Analysis ◽  
Functionally Graded ◽  
Simply Supported ◽  
Piezoelectric Layers ◽  
Curved Panels

AbstractFree vibration analysis of functionally graded (FG) curved panels integrated with piezoelectric layers under various boundary conditions is studied. A panel with two opposite edges is simply supported, and arbitrary boundary conditions at the other edges are considered. Two different models of material property variations based on the power law distribution in terms of the volume fractions of the constituents and the exponential law distribution of the material properties through the thickness are considered. Based on the three-dimensional theory of elasticity, an approach combining the state space method and the differential quadrature method (DQM) is used. For the simply supported boundary conditions, closed-form solution is given by making use of the Fourier series expansion, and applying the differential quadrature method to the state space formulations along the axial direction, new state equations about state variables at discrete points are obtained for the other cases such as clamped or free-end conditions. Natural frequencies of the hybrid curved panels are presented by solving the eigenfrequency equation, which can be obtained by using edges boundary conditions in this state equation. The results obtained for only FGM shell is verified by comparing the natural frequencies with the results obtained in the literature.

Natural Frequencies of Parallelogrammic Plates Using Characteristic Orthogonal Polynomials in Rayleigh-Ritz Method

1992 ◽  
Author(s):  
L. T. Lee ◽  
W. F. Pon
Keyword(s):  
Boundary Conditions ◽  
Coordinate System ◽  
Orthogonal Polynomials ◽  
Natural Frequencies ◽  
Ritz Method ◽  
Energy Functional ◽  
Comprehensive Treatment ◽  
Energy Functionals ◽  
Simply Supported ◽  
Cartesian Coordinate

Abstract Natural frequencies of parallelogrammic plates are obtained by employing a set of beam characteristic orthogonal polynomials in the Rayleigh-Ritz method. The orthogonal polynomials are generalted by using a Gram-Schmidt process, after the first member is constructed so as to satisfy all the boundary conditions of the corresponding beam problems accompanying the plate problems. The strain energy functional and kinetic energy functionals are transformed from Cartesian coordinate system to a skew coordinate system. The natural frequencies obtained by using the orthogonal polynomial functions are compared with those obtained by other methods with all four edges clamped boundary conditions and greet agreements are found between them. The natural frequencies for parallelogrammic plates with other boundary conditions, such as four edges simply supported, clamped-free and simply supported-free, are also obtained. This method is considered as a better and accurate comprehensive treatment for this type of problems.

Vibration Behavior and Serviceability of Arched Prestressed Concrete Truss Due to Human Activity

2018 ◽  
Vol 18 (12) ◽  
pp. 1850146 ◽  
Author(s):  
Jiang Li ◽  
Jiepeng Liu ◽  
Liang Cao ◽  
Y. Frank Chen
Keyword(s):  
Steady State ◽  
Prestressed Concrete ◽  
Natural Frequencies ◽  
Current Trend ◽  
Threshold Values ◽  
Transient Vibration ◽  
Vibration Behavior ◽  
Detailed Evaluation ◽  
Floor Systems ◽  
Floor Vibration

The current trend toward longer spans and lighter floor systems, combined with reduced damping and new activities, have resulted in an increasing complaints on floor vibration from building owners and occupants. Heel-drop, jumping, and walking impacts, which may lead to discomfort problems in daily life, were imposed on a large-span arched prestressed concrete truss (APT) girder system studied. The natural frequencies, peak acceleration, average root-mean-square acceleration (ARMS), maximum transient vibration value (MTVV), and perception factor for the girder were obtained and checked against the existing codes and standards. The purpose of this paper is to provide researchers and engineers with a detailed evaluation on the vibration behavior of the APT girder under different human activities, with a comprehensive review on the relevant criteria and some suggestions. Lastly, the following threshold peak accelerations are suggested: 650[Formula: see text]mm/s2 for transient heel-drop impact, 1450[Formula: see text]mm/s2 for transient jumping impact, and 250[Formula: see text]mm/s2 for steady-state walking. In addition, the threshold values of 90[Formula: see text]mm/s2 and 50[Formula: see text]mm/s2 are suggested for MTVV and ARMS, respectively, under steady-state walking.

Free Vibration of Thin-Walled Open Section Beams With Unconstrained Damping Treatment

1981 ◽  
Vol 48 (1) ◽  
pp. 169-173 ◽  
Author(s):  
S. Narayanan ◽  
J. P. Verma ◽  
A. K. Mallik
Keyword(s):  
Free Vibration ◽  
Cross Section ◽  
Transverse Vibration ◽  
Natural Frequencies ◽  
Vibration Characteristics ◽  
Numerical Results ◽  
Simply Supported ◽  
Clamped Beams ◽  
Thin Walled ◽  
Open Cross Section

Free-vibration characteristics of a thin-walled, open cross-section beam, with unconstrained damping layers at the flanges, are investigated. Both uncoupled transverse vibration and the coupled bending-torsion oscillations, of a beam of a top-hat section, are considered. Numerical results are presented for natural frequencies and modal loss factors of simply supported and clamped-clamped beams.

scholarly journals The Vibration of Simply Supported Non-Uniform Cross Sectional Pipe Conveying Fluid Resting on Viscoelastic Foundation

2020 ◽  
Vol 15 ◽  
Keyword(s):  
Natural Frequencies ◽  
Flexural Vibration ◽  
Bernoulli Model ◽  
Viscoelastic Foundation ◽  
Cross Sectional ◽  
Flowing Fluid ◽  
Simply Supported ◽  
Critical Velocities ◽  
Stiffness And Damping ◽  
The Mathematical Model

The induced flexural vibration of slender pipe systems with continuous non uniform cross sectional area containing laminar flowing fluid lying on extended Winkler viscoelastic foundation is considered. The Euler Bernoulli model of the pipe has hinged ends. The inlet flow is considered constant steady that interacts with the wall of the pipe. The mathematical model is developed and its corresponding solution is obtained. The influence of the combination of variation of cross section, foundation stiffness and damping on the critical velocities, complex natural frequencies and stabilization of the system is presented.

scholarly journals Vibration Analysis of Kenyir Dam Power Station Structure Using a Real Scale 3D Model

2019 ◽  
Vol 29 (3) ◽  
pp. 48-59
Author(s):  
Azizi Arbain ◽  
Ahmad Zhafran Ahmad Mazlan ◽  
Mohd Hafiz Zawawi ◽  
Mohd Rashid Mohd Radzi
Keyword(s):  
Vibration Analysis ◽  
3D Model ◽  
Natural Frequencies ◽  
External Disturbance ◽  
Resonance Phenomenon ◽  
Mode Shapes ◽  
Response Analysis ◽  
Power Station ◽  
Real Scale ◽  
Station Structure

Abstract In this paper, the vibration analysis in terms of modal and harmonic responses are investigated for the power station structure of Kenyir Dam in Terengganu, Malaysia. Modal analysis is carried out to provide the dynamic characteristics of the power station which includes the natural frequencies and mode shapes. Meanwhile, the harmonic response analysis is performed by applying the force to the structure to obtain the Frequency Response Function (FRF) in certain range of frequencies. A real scale three-dimensional (3D) model of the Kenyir Dam power station is constructed using SolidWorks software and imported to ANSYS software for the Finite Element (FE) analysis. A proper boundary condition is taken into consideration to demonstrate the real behaviour of the power station structure. From the results, six most significant natural frequencies and mode shapes including the FRF in all three axes are selected. The highest natural frequency value occurred at 5.4 Hz with the maximum deflection of 0.90361 m in the z axis direction. This value is important in order to verify whether the structure can overcome the resonance phenomenon from the external disturbance forces in the future.

The Natural Frequency Calculation Method of Simply-Supported Beam in the Sunshine Temperature Field

2013 ◽  
Vol 394 ◽  
pp. 364-367
Author(s):  
Yong Chun Cheng ◽  
Yu Ping Shi ◽  
Guo Jin Tan
Keyword(s):  
Temperature Field ◽  
Calculation Method ◽  
Natural Frequencies ◽  
Bernoulli Model ◽  
Simply Supported Beam ◽  
Simply Supported ◽  
Frequency Calculation ◽  
Natural Frequency Calculation ◽  
Beam Bridge ◽  
T Beam

The related researches show that , the sunshine temperature field can cause the changes of the natural frequencies of the simply-supported beam. In order to recover the influence law of the temperature field on the natural frequencies, the calculation method of the natural frequencies of the simply-supported beam bridge is formed. First, according to the principles of stress equivalence, transform the sunshine temperature field to the partiality axis forces. Based on the Bernoulli model, the calculation method of the natural frequencies of the simply-supported beam under the partiality axis forces at both ends is formed. At last, take one simply-supported T beam as the object of numerical modeling and verify the validity and the reliability of this method.

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