Axial Stress - Strain Curve

And Modulus Of Elasticity

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Presented by

Name: : Md. YasinStudent No. :10.01.03.038Section : A4th Year 2nd Semester

Department of civil Engineering Ahsanullah University Of Science and Technology

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In trying to pull the object apart, internal resisting forces are created and these internal forces are known as stress.

 Stress  =  Restoring force / area =  (F)/(A) , where F is the deforming force acting on an area A of the body

STRESS

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STRAIN

The ratio of change produced in the dimensions of a body by  a system of forces or couples, in equilibrium, to its original dimensions is called strain.

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LOAD

STRUCTURE

Stress strain

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REQUIREMENT OF STRESS –STRAIN RELATIONSHIP

To analysis and design members.

It is most important while dealing with reinforced concrete which is a composite material.

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STRESS-STRAIN CURVE

CONCRETE

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STRESS—STRAIN CURVE OF CONCRETE

At first,

As load is applied ,the ratio between stress-strain is approximate linear.

Concrete behaves almost as an elastic material.

If load is removed,displacement is recovered virtually.

Eventually,

The curve is no longer linear.

Behaves more and more as plastic materia.

The shape of stress-strain curve is mostly depend on length of time of loading.

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STRESS-STRAIN CURVE OF CONCRETE

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Stress-strain relationship

It is interesting to note that although cement paste and aggregates individually have linear stress-strain relationships, the behavior for concrete is non-linear. This is due to the mismatch and micro cracking created at the interfacial transition zone.

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STRESS-STRAIN CURVE

STEEL

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Material behavior is generally represented by a stress-strain diagram,which is obtained by conducting a tensile test on a specimen of material.

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– Stress-strain responseis linear.

– Slope = Modulus ofElasticity (Young’smodulus) = E

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– Begins at yield stress Σy

– Slope rapidly decreasesuntil it is horizontal ornear horizontal

– Large strain increase,small stress increase

– Strain is permanent

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– After undergoing largedeformations, the metalhas changed itscrystalline structure.

– The material hasincreased resistanceto applied stress(it appears to be“harder”).

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– The maximum supportedstress value is called theultimate stress, σu.

– Loading beyond σuresults in decreasedload supported andeventually rupture.

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It is defined as the slope of its stress-strain curve in the elastic deformation level.

Modulus of elasticity

E= Stress/Strain

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The modulus of elasticity of concrete is a function of

modulus of elasticity of the aggregates.

the cement matrix.

their relative proportions.

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Stress Modulus of ElasticityAt Low ConstantAt High Decreasing

(cracking)

CHARACTERISTICS

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CHARACTERISTICS

Elements Modulus of Elasticity

Cement harden paste 10-30 Gpa

Aggregates 45-85 Gpa

Concrete Composite 30-50 Gpa

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The modulus of elasticity to be calculated using the following equation

Where,W=weight of concrete

= Compressive strength of concrete at 28 days (psi)

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Yasin , Aust