scholarly journals Who Says Backcalculation Is Only about Layer Moduli?

2019 ◽  
Vol 2673 (1) ◽  
pp. 317-331 ◽  
Author(s):  
Hyung Suk Lee ◽  
Douglas Steele ◽  
Harold Von Quintus
Keyword(s):  
Poisson’S Ratio ◽  
Damping Ratio ◽  
Vertical Direction ◽  
Nonlinear Behavior ◽  
Material Nonlinearity ◽  
Poisson's Ratio ◽  
Unit Weight ◽  
Nonlinear Stress ◽  
Finite Layer ◽  
Stress Dependent

In this study, an existing finite layer algorithm for dynamic analysis of pavement structure was enhanced to incorporate the nonlinear behavior of unbound pavement materials. The nonlinear (stress-dependent) modulus was approximated in the vertical direction, which is similar to the approach used with multi-layered elastic and viscoelastic analysis methods for incorporating material nonlinearity. First, the enhanced finite layer algorithm was used to backcalculate the layer thickness, unit weight, Poisson’s ratio, and damping ratio in addition to the linear (viscoelastic and elastic) modulus of all layers. Then, the parameters backcalculated from the linear analysis were used to estimate the seed values for the subsequent nonlinear analysis in which the stress-dependent moduli of the unbound layers were backcalculated. Deflection data from two field sections (with thick and thin asphalt concrete layer) were used for demonstration. The results showed excellent agreement between the measured and backcalculated deflection time histories. In addition, it was found that the use of backcalculated parameters for the thickness, unit weight, Poisson’s ratio, and damping resulted in lower errors for both the linear and nonlinear analyses. Furthermore, the results of the backcalculation indicated that the material nonlinearity was more pronounced for the thin pavement, in which case the backcalculation error may be reduced further by incorporating the stress-dependent modulus.

Study on a New Testing Method of the Elastic Modulus and Poisson's Ratio by Using Brazilian Disk Test

2013 ◽  
Vol 347-350 ◽  
pp. 1199-1202
Author(s):  
Fei Wu ◽  
Shi Ming Dong
Keyword(s):  
Elastic Modulus ◽  
Poisson’S Ratio ◽  
Vertical Direction ◽  
Test Method ◽  
Poisson's Ratio ◽  
Theoretical Formula ◽  
Brazilian Disk ◽  
Total Displacement ◽  
The Relationship ◽  
Poissons Ratio

In order to develop a new test method of the elastic modulus and Poissons ratio, based on the theoretical analysis of the Brazilian disk diametrically loaded by a pair of forces, the relationship is obtained between the total displacement of one point on the vertical direction of the load line and the applied force as well as the elastic modulus and Poissons ratio. The strain gauges with different length are used to measure the displacement of the corresponding point, and then the displacement is employed to calculate the elastic modulus and Poisson's ratio by using the theoretical formula. The proposed method can provide a new approach to estimate the elastic modulus and Poissons ratio by using Brazilian disk splitting tests.

scholarly journals STUDY ON NONLINEAR PAVEMENT RESPONSES OF LOW VOLUME ROADWAYS SUBJECT TO MULTIPLE WHEEL LOADS / NETIESINĖS KELIO DANGOS PRIKLAUSOMYBĖS NUO MAŽO INTENSYVUMO KELIŲ, VEIKIAMŲ DAUGKARTINĖMIS RATŲ APKROVOMIS, TYRIMAS

2011 ◽  
Vol 17 (1) ◽  
pp. 45-54 ◽  
Author(s):  
Minkwan Kim ◽  
Joo Hyoung Lee
Keyword(s):  
Finite Element ◽  
Numerical Study ◽  
Asphalt Pavement ◽  
Three Dimensional ◽  
Nonlinear Behavior ◽  
Element Model ◽  
Element Analysis ◽  
Nonlinear Stress ◽  
Low Volume ◽  
Stress Dependent

This paper describes numerical analyses on low volume roads (LVRs) using a nonlinear three-dimensional (3D) finite element model (FEM). Various pavement scenarios are analyzed to investigate the effects of pavement layer thicknesses, traffic loads, and material properties on pavement responses, such as surface deflection and subgrade strain. Each scenario incorporates a different combination of wheel/axle configurations and pavement geomaterial properties to analyze the nonlinear behavior of thinly surfaced asphalt pavement. In this numerical study, nonlinear stress-dependent models are employed in the base and subgrade layers to properly characterize pavement geomaterial behavior. Finite element analysis results are then described in terms of the effects of the asphalt pavement thickness, wheel/axle configurations, and geomaterial properties on critical pavement responses. Conclusions are drawn by the comparison of the nonlinear pavement responses in the base and subgrade in association with the effects of multiple wheel/axle load interactions. Santrauka Straipsnyje aprašoma skaitinė mažo intensyvumo kelių analizė, taikant netiesinį—erdvinį baigtinių elementų modelį. Skirtingi dangų paviršiaus variantai analizuojami siekiant ištirti, kokiąįtaką kelio dangos elgsenai, t. y. poslinkiams ir kelio pagrindo deformacijoms, turi dangų sluoksnių storiai, eismo apkrovos ir medžiagų savybės. Kiekvienas kelio dangos variantas turi skirtingas ratų arba ašies ir geometrinių savybių formas, kad būtų galima išanalizuoti netiesinę plonos asfalto dangos paviršiaus elgseną. Šioje skaitinėje analizėje nagrinėjami netiesiniai įtempių modeliai, kurie buvo taikomi pagrindo sluoksniams, siekiant tinkamai apibūdinti geometrinę kelio dangos elgseną. Baigtinių elementų analizės rezultatai toliau nagrinėjami atsižvelgiant į asfalto dangos storį ar ašies formą ir geometrines savybes, priklausomai nuo kritinės kelio dangos būklės. Išvados buvo gautos lyginant netiesines kelių dangos priklausomybes pagrindo sluoksnyje, atsižvelgiant į jų sąveiką su daugkartine ratų apkrova.

Usage of Digital Image Correlation (DIC) in Determination of Modulus of Elasticity and Poisson's Ratio of Special Concrete

2018 ◽  
Vol 272 ◽  
pp. 154-159
Author(s):  
Vladimír Suchánek ◽  
Tomáš Bednarz ◽  
Tomáš Svojanovský
Keyword(s):  
Reinforced Concrete ◽  
Modulus Of Elasticity ◽  
Poisson’S Ratio ◽  
Vertical Direction ◽  
High Strength ◽  
Image Correlation ◽  
Poisson's Ratio ◽  
Fibre Reinforced Concrete ◽  
Steel Fibre Reinforced Concrete

This paper deals with an evaluation of long-term experimental work carried out in cooperation with concrete suppliers and a specific company (named Sobriety). The key part of this work is focused on the experimental determination of secant modulus of elasticity and Poisson's Ratio of special concrete (self-compacting concrete, steel fibre reinforced concrete, polymer fibre reinforced concrete, specific high-strength concrete). Two different real-time approaches were used to detect modulus of elasticity. In parallel, both approaches - the (European) standard approach and the DIC (2D DIC; 3D DIC with varying lengths in the vertical direction) - were applied.

Modeling the Biaxial Behavior of Concrete by Damage Mechanics with Poisson’s Ratio Variable

2015 ◽  
Vol 749 ◽  
pp. 391-397 ◽  
Author(s):  
Rebiha Smahi ◽  
Youcef Bouafia ◽  
Mohand Said Kachi
Keyword(s):  
Continuum Mechanics ◽  
Poisson’S Ratio ◽  
Damage Mechanics ◽  
Three Dimensional ◽  
Nonlinear Behavior ◽  
Poisson's Ratio ◽  
Biaxial Compression ◽  
Mechanics Of Materials ◽  
Linear Behavior ◽  
The Continuum

A new model is introduced, for predicting the nonlinear behavior of the concrete until the rupture. The non-linear behavior of the concrete is taken into account under monotonic load verifying the principles of the mechanics damage [1] and the concepts of the mechanics of the fracture, using the foundations of the continuum mechanics of materials [2]. The nonlinear mechanical behavior of the concrete in unidirectional is described by two laws (Sargin [3] for the compression and Grelat [4] on the tension). By introducing two variables of damage applied in unidirectional respectively in tension and in compression (Y. Bouafia , R. Smahi, and al., (2014)) [5]. Their combination with the laws of the continuum mechanics of materials (Hooke’s low generalized) [2], and the theory of the mechanics damage (theory of the isotropy of the damage, and principle of the equivalent deformation), brings us to a law of variation of the damage in three-directional applied in bidirectional. In addition, if the variation of the Poisson’s ratio of concrete in unidirectional compression has attracted the interest of several researchers we can cites: (Sami, A., Klink, 1975 [6], Murray D.W. 1979 [7], Niels Saabye ottosen, (1980) [8], Atheel E. Allos., L.H.Martin, (1981) [9], Ramtani.S, Y. Berthaud , J. Mazars, (1992) [10] and Ferretti, E., (2004) [11]. For the three-dimensional, we can mention: Chen 1982 [12], Guo 1997 [13], Zhu 1998 [14], Hyuk-Chun Noh, Hyo-Gyoung Kwak 2006 [15] and Ding Faxing Yu Zhiwu 2006 [16]. Confrontations of the calculations with experimental results (behavior of the concrete in biaxial compression and tension) have allowed to describe and to follow the real behavior of the concrete.

The Model for Calculating Elastic Modulus and Poisson's Ratio of Coal Body

2013 ◽  
Vol 6 (1) ◽  
pp. 36-43 ◽  
Author(s):  
Ai Chi ◽  
Li Yuwei
Keyword(s):  
Elastic Modulus ◽  
Poisson’S Ratio ◽  
Fractured Rock ◽  
Rock Block ◽  
Poisson's Ratio ◽  
Linear Elastic ◽  
Study Results ◽  
The Face ◽  
Block Face ◽  
Coal Rock

Coal body is a type of fractured rock mass in which lots of cleat fractures developed. Its mechanical properties vary with the parametric variation of coal rock block, face cleat and butt cleat. Based on the linear elastic theory and displacement equivalent principle and simplifying the face cleat and butt cleat as multi-bank penetrating and intermittent cracks, the model was established to calculate the elastic modulus and Poisson's ratio of coal body combined with cleat. By analyzing the model, it also obtained the influence of the parameter variation of coal rock block, face cleat and butt cleat on the elastic modulus and Poisson's ratio of the coal body. Study results showed that the connectivity rate of butt cleat and the distance between face cleats had a weak influence on elastic modulus of coal body. When the inclination of face cleat was 90°, the elastic modulus of coal body reached the maximal value and it equaled to the elastic modulus of coal rock block. When the inclination of face cleat was 0°, the elastic modulus of coal body was exclusively dependent on the elastic modulus of coal rock block, the normal stiffness of face cleat and the distance between them. When the distance between butt cleats or the connectivity rate of butt cleat was fixed, the Poisson's ratio of the coal body initially increased and then decreased with increasing of the face cleat inclination.

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