Presentation on theme: "Modulus of Elasticity and Poisson Ratio of Concrete"— Presentation transcript:
1Modulus of Elasticity and Poisson Ratio of Concrete Benjie Cho and Mulugojam AlemuUndergraduate Civil EngineeringUniv.. of Southern California
2Objective Find the Modulus of Elasticity of Concrete Find Poisson’s Ratio of Concrete
3Introduction Compressive Strength of Concrete Standardardized test of concreteAmerican Society for Testing and Materials (ASTM)Specifications includeCorrect mixProperly affixing strain gaugesProperly capping the cylinder with sulfur
4ProcedureSelect (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.
5ProcedureAffix 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.
6ProcedureSet gauge factor to /- .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.
7Organizing the dataCompute 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.
8Calculation procedures Young’s ModulusE=(s1-s2)/(e )s1=The stress corresponding to the longitudinal strain of 50 micro strain.s2=The stress corresponding to .4f ‘c.E2=The longitudinal strain corresponding to s2.Based on ASTM C 469Poisson’s Ration=(Lateral Strain)/(Longitudinal Strain)