Spirally bound concrete columns

1985 ◽  
Vol 400 (1818) ◽  
pp. 127-144 ◽  
Keyword(s):  
Cross Section ◽  
Material Properties ◽  
Circular Cross Section ◽  
Plain Concrete ◽  
Concrete Columns ◽  
Stress Strain Relation ◽  
Mathematical Expressions ◽  
Iterative Procedures ◽  
Theoretical Results ◽  
Good Agreement

In this paper, mathematical expressions for the material properties of plain concrete are used in conjunction with the stress–strain relation of steel reinforcement to develop equations for both the strength and deformational behaviour of axially loaded concrete columns of circular cross section and with closely spaced spiral binding. Iterative procedures are used to solve these equations and the theoretical results are shown to be in good agreement with experimental results obtained by earlier investigators.

Vibration Characteristics of Straight Blades of Asymmetrical Aerofoil Cross-Section

1969 ◽  
Vol 20 (2) ◽  
pp. 178-190 ◽  
Author(s):  
W. Carnegie ◽  
B. Dawson
Keyword(s):  
Analytical Solution ◽  
Cross Section ◽  
Natural Frequencies ◽  
Equations Of Motion ◽  
Limited Range ◽  
First Order ◽  
Special Cases ◽  
Theoretical Results ◽  
Theoretical Procedure ◽  
Good Agreement

SummaryTheoretical and experimental natural frequencies and modal shapes up to the fifth mode of vibration are given for a straight blade of asymmetrical aerofoil cross-section. The theoretical procedure consists essentially of transforming the differential equations of motion into a set of simultaneous first-order equations and solving them by a step-by-step finite difference procedure. The natural frequency values are compared with results obtained by an analytical solution and with standard solutions for certain special cases. Good agreement is shown to exist between the theoretical results for the various methods presented. The equations of motion are dependent upon the coordinates of the axis of the centre of flexure of the beam relative to the centroidal axis. The effect of variations of the centre of flexure coordinates upon the frequencies and modal shapes is shown for a limited range of coordinate values. Comparison is made between the theoretical natural frequencies and modal shapes and corresponding results obtained by experiment.

STRESS-STRAIN STATE OF ECCENTRICALLY COMPRESSED REINFORCED CONCRETE COLUMNS OF CIRCULAR CROSS-SECTION

2018 ◽  
Vol 8 (1) ◽  
pp. 4-9
Author(s):  
Sergey S. MORDOVSKY ◽  
Rustam I. DAVLIKAMOV
Keyword(s):  
Reinforced Concrete ◽  
Cross Section ◽  
Nonlinear Deformation ◽  
Strain State ◽  
Circular Cross Section ◽  
Concrete Columns ◽  
Deformation Model ◽  
Stress Strain ◽  
Reinforced Concrete Columns ◽  
Nonlinear Deformation Model

Theoretical studies of reinforced concrete eccentrically compressed columns of circular cross-section on strength indexes are analyzed. These studies rely on the use of a nonlinear deformation model that approximates the work of concrete to real experimental conditions. A comparative analysis of the results of calculating the strength of reinforced concrete columns of circular cross-section is carried out according to the methodology proposed in the current set of rules, is the author’s program for determining the stress-strain state of a reinforced concrete column of circular cross-section implemented in the MathCad software environment. The results of a numerical experiment are compared in the form of a fi nite-element model in the Lira-CAD program complex using a nonlinear deformation model. Calculations and schemes are given taking into account the possibility of conducting an experimental study.

In-Plane Vibrations of Thick Circular Rings With T or I Cross Sections

1979 ◽  
Vol 46 (2) ◽  
pp. 470-472
Author(s):  
H. Lecoanet ◽  
J. Piranda
Keyword(s):  
Experimental Data ◽  
Eigenvalue Problem ◽  
Cross Section ◽  
Cross Sections ◽  
Rectangular Cross Section ◽  
Circular Rings ◽  
Theoretical Results ◽  
Good Agreement

This paper deals with the problem of eigenfrequencies and eigenvectors for rings whose cross section may be decomposed in basic rectangular cross sections. The solution is derived from a solution of the in-plane eigenvalue problem for rectangular cross-section thick rings. A good agreement between theoretical results and experimental data is obtained.

Stress-Strain Relation in Rubber Blocks under Compression. I

1959 ◽  
Vol 32 (2) ◽  
pp. 409-419
Author(s):  
Géza Schay ◽  
Péter Ször
Keyword(s):  
Experimental Data ◽  
Free Surface ◽  
Cross Section ◽  
Experimental Error ◽  
Stress Strain ◽  
General Applicability ◽  
Empirical Constant ◽  
Strain Relation ◽  
Stress Strain Relation ◽  
Good Agreement

Abstract For the stress-strain relation of differently shaped rubber blocks submitted to compression, an equation of general applicability is deduced, starting from the idea that compression work must be done also against the tension arising through the increase of the free surface. In this equation the stress is not a function of the compression ratio only, but of the ratio of the fixed to the free surface as well. Besides the shear modulus of the block's substance, this equation involves a single empirical constant which changes only slightly with the shape of the block's cross section. The validity of the equation obtained was tested by measurements performed by the authors on cylinders as well as by data on quadratic prisms published in previous literature. The calculated values are in good agreement with the experimental data within the limits of experimental error.

Rise in optimized capillary channels

2013 ◽  
Vol 731 ◽  
pp. 142-161 ◽  
Author(s):  
B. Figliuzzi ◽  
C. R. Buie
Keyword(s):  
Cross Section ◽  
Silicone Oil ◽  
Capillary Rise ◽  
Circular Cross Section ◽  
Heat Pipes ◽  
Design And Optimization ◽  
The Subject ◽  
Micro Heat Pipes ◽  
Good Agreement ◽  
Optimal Radius

AbstractMany technological applications rely on the phenomenon of wicking flow induced by capillarity. However, despite a continuing interest in the subject, the influence of the capillary geometry on the wicking dynamics remains underexploited. In numerous applications, the ability to promote wicking in a capillary is a key issue. In this article, a model describing the capillary rise of a liquid in a capillary of varying circular cross-section is presented. The wicking dynamics is described by an ordinary differential equation with a term dependent upon the shape of the capillary channel. Using optimal control theory, we were able to design optimized capillaries which promote faster wicking than uniform cylinders. Numerical simulations show that the height of the rising liquid was up to 50 % greater with the optimized shapes than with a uniform cylinder of optimal radius. Experiments on specially designed capillaries with silicone oil show a good agreement with the theory. The methods presented can be useful in the design and optimization of systems employing capillary-driven transport including micro-heat pipes or oil extracting devices.

scholarly journals Efficiency of Hysteresis Rods in Small Spacecraft Attitude Stabilization

2013 ◽  
Vol 2013 ◽  
pp. 1-17 ◽  
Author(s):  
Assal Farrahi ◽  
Ángel Sanz-Andrés
Keyword(s):  
Thin Film ◽  
Cross Section ◽  
Circular Cross Section ◽  
Semiempirical Method ◽  
Spacecraft Attitude ◽  
Flight Data ◽  
Small Satellites ◽  
Attitude Stabilization ◽  
Section Shape ◽  
Good Agreement

A semiempirical method for predicting the damping efficiency of hysteresis rods on-board small satellites is presented. It is based on the evaluation of dissipating energy variation of different ferromagnetic materials for two different rod shapes: thin film and circular cross-section rods, as a function of their elongation. Based on this formulation, an optimum design considering the size of hysteresis rods, their cross section shape, and layout has been proposed. Finally, the formulation developed was applied to the case of four existing small satellites, whose corresponding in-flight data are published. A good agreement between the estimated rotational speed decay time and the in-flight data has been observed.

Modal Curves of Pre-Twisted Beams of Rectangular Cross-Section

1969 ◽  
Vol 11 (1) ◽  
pp. 1-13 ◽  
Author(s):  
B. Dawson ◽  
W. Carnegie
Keyword(s):  
Cross Section ◽  
Rectangular Cross Section ◽  
Twist Angle ◽  
Ritz Method ◽  
Transformation Method ◽  
Mode Shapes ◽  
Modes Of Vibration ◽  
Vibrational Characteristics ◽  
Theoretical Results ◽  
Good Agreement

An important aspect of the theoretical study of the vibrational characteristics of turbine and compressor blading is the prediction of the modal curves from which the stresses along the length of the blading can be determined. The accurate prediction of the modal curves allowing for such factors as pre-twist, camber, size of cross-section, centrifugal tensile effects, aerodynamic effects, etc., is still not possible. However, a better understanding of the effects of some of these parameters can be obtained by a study of the modal curves of relatively simple idealized models. In this work the theoretical mode shapes of vibration of pre-twisted rectangular cross-section beams for various width to depth ratios and pre-twist angle in the range 0-90° are examined. The theoretical results are obtained by the transformation method given by Carnegie, Dawson and Thomas (1)† and the accuracy of these results is verified by comparison with results obtained by Dawson (2) using the Ritz method. The theoretical results are compared to modal curves determined experimentally and good agreement is shown between them. A physical explanation of the effects of the pre-twist angle upon the modal curves is given for the first three modes of vibration.

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