Benjie Cho and Mulugojam Alemu Undergraduate Civil Engineering Univ of Southern California Objective Find the Modulus of Elasticity of Concrete Find Poissons Ratio of Concrete Introduction ID: 692109
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Slide1
Modulus of Elasticity and Poisson Ratio of Concrete
Benjie Cho and Mulugojam Alemu
Undergraduate Civil Engineering
Univ.. of Southern CaliforniaSlide2
Objective
Find the Modulus of Elasticity of Concrete
Find Poisson’s Ratio of ConcreteSlide3
Introduction
Compressive Strength of Concrete
Standardardized test of concrete
American Society for Testing and Materials (ASTM)
Specifications include
Correct mix
Properly affixing strain gauges
Properly capping the cylinder with sulfurSlide4
Procedure
Select (5) 4in diameter by 12in length concrete with 28-day age with 4 ksi design strength.
Cap all the bearing surfaces with sulfur to make the end flat.
Mark area where strain gauges will be attached.
Clean area with chemical cleaners and sand paper.Slide5
Procedure
Affix strain gauges on their designated area, one vertical and one horizontal, using glue.
Attach wire to strain gauges by soldering.
Test voltage of the strain gauges.
Place and center samples on the Satec Universal Testing Machine.
Connect the wires to the P3500 strain indicator, which in turn is connected to a computer for recording.
Slide6
Procedure
Set gauge factor to 2.055 +/- .5% and zero the strain readings.
Begin loading the specimens and record values of strain for given loads.
Continue testing until failure of the specimen. Slide7
Organizing the data
Compute the stress by dividing the load by the cross-sectional area.
Graph the strength against the vertical and horizontal strains of each specimen.
Find values for the Young’s Modulus and Poisson’s ratio from the data.
Calculate the theoretical values the Young’s Modulus and Poisson’s ratio.Slide8
Calculation procedures
Young’s Modulus
E=(s
1
-s
2
)/(
e
2
-.000005)
s
1
=The stress corresponding to the longitudinal strain of 50 micro strain.
s
2
=The stress corresponding to .4f ‘c.
E
2
=The longitudinal strain corresponding to s
2
.
Based on ASTM C 469
Poisson’s Ratio
n
=(Lateral Strain)/(Longitudinal Strain)Slide9
ExampleSlide10
Cylinder #2Slide11
Cylinder #3Slide12
Cylinder #4Slide13
Cylinder #5Slide14
Selected Values of Stress and StrainSlide15
Selected Values of Stress and StrainSlide16
DataSlide17
Conclusion
All specimens performed under the theorectical values of E.
Average E= 2.60E6 psi
Average Poisson Ratio= .119691Slide18
Conclusion
Concrete performed to design specifications.
E= 1.5 - 5 ksi
n
= .1
Xiao, Yan. Experimental Analysis of Engineering Materials. University of Southern California lecture notes 2002.