Compressive strength vs tensile strength, hi guys in this article we know about what is compressive and tensile strength?, what is compressive stress & strain. And also know about difference between compressive strength and tensile strength and their relationship.
You know that properties of Material compressive strength and tensile strength is require for prediction of measuring various strength of column,beam,slab and truses.
All the concrete structure divided into three categories on the basis of compression and tension 1) compressive member,2) tension member and 3) Flexural member.
Beam and slab experience both compression and tension, that’s why they are called as flexural. They experience compression in upper part of neutral axis which resist by providing concrete and reinforcement and experience tension in lower part of neutral axis which is resist by providing main reinforcement, that’s why beam and experience both compression and tension and their failure is by bending.
Column is compressive member in which all the load of slab and beam horizontally transfer to column acting vertically downward, compressing dimension of column along the length,so column experience compressive load acting downward due to load of slab and beam and other structure. And also column due to internal force experience compressive force in upward direction which tends to resist the load acting in downward, so column will experience both opposite and equal forces of compressive load, that’s why column is compressive member and their failure is by buckling.
Compressive strength is ability of material which resist or withstand against compressive load acting both face along rising length (cross-sectional area) by reducing its size prior to failure. It is resistance of material against pushing force in equal and opposite direction.
Tensile strength is ability of material with resist or withstand against tensile load acting on both face along rising length by stretch or elongate prior to failure or crack. It is Resistance of material against using pulling force in equal and opposite direction.
In this article we discuss about difference between compressive strength and tensile strength (compressive strength vs tensile strength). Before this,let us discuss about elasticity and plasticity properties of Material which help in understanding compressive and tensile strength.
Elastic properties of Material like concrete and steel, when tensile forces acting on both face of concrete or steel, stretch it, and develop stress, if material regain its original shape size without deformation after removing stress is known as elastic properties of Material.
Plastic properties of Material like concrete and steel, when tensile forces acting on both face of concrete or steel, stretch it and develop stress, if material do not regain its original shape and size after removing stress, material will deform is known as plastic properties of Material.
What is compressive strength? Stess & Strain
Compressive strength is the capacity of material or structure to resist or withstand under compressive load. The Compressive strength is determined by the ability of the concrete material to resist failure in the form cracks and fissure. The maximum load at which the specimen breaks is taken as a compressive load.
Compressive strength is defined as resistance of material under compression prior to failure or fissure, it can be expressed in terms of load per unit area and measured in MPa. For example compressive strength of M20concrete is 20MPa.
In compressive strength test of concrete, steel and other construction material the push force applied on the both faces of material specimen and the maximum compression that specimen bears without failure is noted.
Compressive Force acting on concrete testing specimen helps us to majorly focus on the Compressive strength of concrete because it helps us to quantify the ability of concrete to resists Compressive stresses among structures where-as other stresses such as axial stresses and tensile stresses are catered by reinforcement and other means.
As we know compressive strength is measured by compressive strength test machine (CTM) or Universal testing machine (UTM)
Mathematically, Compressive strength is defined as ratio of compressive load applied by UTM machine to cross sectional area of material.
Compressive strength is represented by F which is equal to F = P/A, where F = compressive strength,P= total load applied by CTM machine & A = cross sectional surface area.
Generally compressive strength in English system of unit measured in pound force per square inch represented as psi, and MPa or N/mm2 in SI unit which is used in India and other country.
What is compressive stress?
Compressive stress is load acting per unit area under compression in which material is push by equal and opposite force along length of rising, material is compressed and develop compressive stress which is the represented by symbol Sigma (σ).
material reduce in size to resist or withstand compressive stress prior to failure of structure. The maximum load at which the specimen breaks is taken as a compressive load and maximum stress at which specimen is break or failure is known as compressive stress.
Mathematically compressive stress is defined as ratio of maximum load to the cross-sectional area of specimen,such as
Compressive stress = load/Area
σ = F/A
Where σ = compressive stress
F = maximum load acting on a specimen
A = cross sectional area of specimen.
Simply we can say that compressive stress is equal to compressive strength of material.
What is compressive strain?
Compressive strain is ratio of decrease in length to original length under compression stress. The material which are under compression reduce in size to withstand with compressive load prior to failure.(ε = ∆ℓ/ℓ0)
Consider specimen have lo length before compression and their final length is l after compression, so decrease in length (∆ℓ = l – lo). Compressive strain is fractional decrease in length which is represented by formula ε = _ (∆ℓ/ℓ0)
Compressive strain = decrease in length/ original length
Compressive strain ε = _ (∆ℓ/ℓ0))
Where ε = compressive stress
_ (∆ℓ/ℓ0)) = fractional degree in length.
What is elastic modulus?
Elastic modulus measure the stiffness of material when stress is applied and it experience is strain, the material concrete and steel have elastic properties.
Mathematically elastic modulus is the ratio of stress to strain, it is represented by E = σ/ε.
Elastic modulus = stress/strain
E = σ/ε or F/A ÷ (∆ℓ/ℓ0))
E = (F × ℓ0)/(A×∆ℓ)
Where, E = elastic modulus
F/A = σ = stress
(∆ℓ/ℓ0 = ε = strain.
What is tensile strength? Stress & Strain
Tensile strength is resistance of material under tension. When two equal and opposite pulling forces is applied over specimen, stress is develop known as tension stress which causes stretching or elongation in specimen, so tensile strength is maximum strength of material to resist or withstand against tension prior to failure.
The maximum load at which the specimen breaks is taken as tensile load and maximum stress at which specimen break is taken as tensile stress. The material which are under tension are increased in size stretch or elongate. In general words tensile strength is define as resistance of material to Breaking under tension stress.
Tensile strength is maximum load that a material can support without fracture when being stretched. Tensile strengths is mathematically represented as force per unit area
Tensile strength = Load/Area
F = P/A
Where F = tensile strength
P = maximum tensile load acting on specimen
A = cross sectional area of specimen
Tensile strength measured in psi in the English system of measurement are commonly expressed in units of pounds per square inch, often abbreviated to psi and MPa in SI used in India and other country,1MPa is equal to N/mm2.
stresses less than the tensile strength are removed, a material returns either completely or partially to its original shape and size. As the stress reaches the value of the tensile strength, however, a material, if ductile, that has already begun to flow plastically rapidly forms a constricted region called a neck, where it then fractures.
What are types of tensile strength?
There are three types of tensile strength 1) Yield strength,2) Ultimate strength and 3) Breaking or splitting strength.
● 1) Yield strength: the tensile stress of a material can withstand or resist without permanent deformation.
When pulling forces is applied on specimen, it will elongate or strech upto elastic limit without deformation,it means Yield strength is stress of material at the point of end of Elastic stage and beginning of plastic property, when tensile stress is removed material regain its shape and size without deformation.
● 2) Ultimate strength:- the maximum tensile stress a material can withstand or resist without breaking, ultimate strength is maximum stress at the point of end of plastic stage in strain stress curve prior to break.
When tensile stress is removed material do not regain its original shape and size because stretching beyond the elastic stage upto end of plastic stage. Material in plastic stage experience Irreversible and in elastic stage is a reversible. Due to ultimate stress material will deform but do not break.
● 3) Breaking or splitting strength: the maximum tensile stress a material can not able to withstand or resist causing breaking. It is defined as resistance of a material to breaking under tensile stress. Breaking tensile stress is developed at the end of plastic stage of material in strain stress curve.
So it is clear that value of breaking tensile strength is higher than ultimate strength and yield strength in respective manner such as breaking tensile strength > ultimate strength > Yield strength.
What is tensile stress?
Tensile stress is load acting per unit area under tension in which material is pull by equal and opposite force along length of rising, material is strech and develop tensile stress which is the represented by symbol Sigma (σ).
material increase in size to resist or withstand tensile stress prior to failure of structure. The maximum load at which the specimen breaks is taken as a tensile load and maximum stress at which specimen is break or failure is known as tensile stress.
Mathematically tensile stress is defined as ratio of maximum load to the cross-sectional area of specimen,such as
Tensile stress = load/Area
σ = F/A
Where σ = tensile stress
F = maximum load acting on a specimen
A = cross sectional area of specimen.
Simply we can say that tensile stress is equal to tensile strength of material.
What is tensile strain?
Tensile strain is ratio of increase in length to original length under tension stress. The material which are under tension increase in size to withstand with tensile load prior to failure.
Consider specimen have lo length before compression and their final length is l after compression, so increase in length (∆ℓ = l – lo). Tensile strain is fractional increase in length which is represented by formula ε = + (∆ℓ/ℓ0)
Tensile strain = increase in length/ original length
Tensile strain ε = + (∆ℓ/ℓ0))
Where ε = tensile stress
+ (∆ℓ/ℓ0)) = fractional increase in length.
Compressive strength vs tensile strength
Let us now discuss difference between compressive strength and tensile (strengthCompressive strength vs tensile strength). There are following difference between two
Compressive strength vs tensile strength is comparison of strength in which compressive strength is pushing force tends to reduce the size of material after compression whereas tensile strength is pulling force tends to increase the size of material after tension.
● 1) compressive strength of concrete is higher than tensile strength, concrete experience good behave in compression whereas poor behave in tension.
Maximum compressive strength of M20 concrete is 20MPa whereas maximum tensile strength is only about 10 to 12% of compressive strength.
Assume compressive strength of concrete is 20MPa,consider its tensile strength about 10%,then 10% of 20MPa = 2MPa, so concrete tension stress is 2MPa. So concrete experience good behaviour in compression whereas poor behaviour in tension.
● 2) tensile strength of steel is higher than compressive strength, steel experience good behave in tension whereas poor behave in compression.
Yield strength and tension strength of Fe250 is 250MPa and 410MPa respectively, tensile strength is 410MPa whereas maximum compressive strength is only about 35 to 40% of tensile strength.
Assume tensile strength of Fe250 steel is 410MPa,consider its compressive strength about 35% to 40%,then 30% to 40% of 410MPa = 140MPa to 160MPa, so steel compression stress is ranging between 140MPa to 160MPa. So steel experience good behaviour in tension whereas poor behaviour in compression.
● 3) in compression stress there is fractional decrease in length where as intention is stress there is fractional increase in length, so compressive strain is negative and tensile strain is positive.
Fractional decrease in length ε = _ (∆ℓ/ℓ0)
Fractional increase in length ε = + (∆ℓ/ℓ0)
● 4) compressive strength is pushing force which is equal and opposite force apply along the both face of length of rising of material, compressed it, and thereby decreasing its length, whereas tensile strength is pulling force which is equal and opposite force apply along both face along length of rising of material,it stretch and thereby increasing its length.
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