45 Questions
What type of material exhibits linear elastic behavior followed by plastic response?
Elasto-plastic material
What happens to the strain when the stress applied on a specimen is increased, in a material that exhibits linear elastic behavior?
The strain increases proportionally
What is the characteristic of a material that exhibits plastic response?
The material deforms permanently under stress
What is the typical shape of the stress-strain curve of a plastic material?
Non-linear
What is the yield strength of the aluminum alloy in the example?
150 MPA
What is the change in gauge length of the rod after applying the tensile load?
0.1 mm
What is the definition of elastic materials?
Materials that have the ability to recover their original shape after removal of the load
What is the purpose of drawing a stress-strain curve?
To analyze the behavior of a material under different types of loading
What is the formula for Young's modulus?
E = σ / ε
What is the definition of plastic materials?
Materials that cannot recover their original shape after removal of the load
What type of material is concrete?
Elasto-plastic material
What is the unit of Young's modulus?
Pa
What is the relationship between stress and strain in the elastic region of a stress-strain curve?
Stress is directly proportional to strain
What is the effect of increasing Young's modulus on a material?
It becomes more difficult to deform
What is Poisson's ratio?
A measure of a material's ability to deform laterally
What is the normal strain in the given example?
0.025/50
What is the normal stress in the given example?
8 KN
What is the change in diameter of the steel bar in the given example?
0.0015 mm
What is the primary factor that determines the response of a material to loads?
Properties of the material
What is the unit of stress?
MPa
What is the formula for calculating stress?
P / A
What type of stress occurs when a force is applied parallel to a surface?
Shear stress
What is the definition of strain?
Change in length divided by original length
What is the dimension of strain?
Length/Length
What is the formula for calculating strain?
ΔL / L
What is the importance of considering the mechanical properties of building materials?
To ensure durability and resistance to failure
What is the term for the ability of a material to resist failure under the action of stresses?
Strength
What type of strain is the strain that subsides after the removal of the applied stress?
Elastic strain
What is the stress range that does not cause plastic strain?
Elastic range
What is the maximum stress that can be applied on a material before it fails?
Ultimate stress
What is the ability of a material to endure alternate wet and dry conditions for a long period without considerable deformation and loss of mechanical strength?
Weathering Resistance
What is the capacity of a material to allow water to penetrate under pressure?
Water Permeability
What is the ability of a water-saturated material to endure repeated freezing and thawing with considerable decrease of mechanical strength?
Frost Resistance
What is the increase in stresses by an increase in strain without collapse in the material?
Strain Hardening
A material with a stress-strain relation has a modulus of elasticity of 2510^6 Psi, yield strength of 70 ksi, and the slope of hardening portion of the stress-strain diagram is 310^6 psi. What is the strain that corresponds to a stress of 80 ksi?
3.2%
A steel rod is subjected to an axial pulling force of 50 kN. Its diameter is 30 mm and it is 3 m long. What is the percentage of elongation of the steel rod?
1.0%
What is the primary characteristic of fire resistance in a material?
Ability to resist high temperature without deformation and loss of strength
Which property of a material is related to its ability to resist abrasion?
Abrasive resistance
What is the unit of the abrasion ratio (N) in the given formula?
gm/cm2
What is the term for the ability of a material to resist the action of acids, alkalis, seawater, and gases?
Chemical resistance
What is the term for the ability of a material to resist the combined effects of atmospheric and other factors?
Durability
What is the term for the property of a material to resist pressing-in or scratch of a sharp object?
Hardness
What is the formula for calculating the abrasion ratio (N)?
N = (m1 - m2)/A
What is the purpose of calculating the abrasion ratio (N)?
To determine the abrasive resistance of a material
What is the term for the ability of a material to resist deformation and substantial loss of strength under high temperature?
Fire resistance
Study Notes
Mechanical Properties of Building Materials
- Materials deform in response to loads, and their specific response depends on properties, load magnitude and type, and element geometry.
- Important mechanical properties of building materials include strength, compressive, tensile, bending, impact, hardness, plasticity, elasticity, and abrasion resistance.
- Strength of materials is the ability to resist failure under stress caused by loads, including compression, tension, bending, and impact.
Stress and Strain
- Stress (σ) is the amount of force applied to a unit of area (N/mm²) and is defined as load (P) divided by area (A).
- Strain (ε) is the amount of deformation per unit length of an object when a load is applied and is defined as change in length (ΔL) divided by original length (L).
- Strain is dimensionless and has dimensions of [Length]/[Length].
Types of Stress
- There are several types of stress, including compression stress, tension stress, shear stress, and torsion stress.
Classification of Building Materials
- Materials can be classified according to their nature of deformation:
- Elastic materials: recover their original shape after removal of the load (e.g. rubber).
- Plastic materials: cannot recover their original shape after removal of the load (e.g. clay).
- Elasto-plastic materials: recover part of the changes in their shape after removal of the load (e.g. steel, concrete, and wood).
Modulus of Elasticity
- Young's modulus (E) is a measure of the ability to resist deformation and is defined as the proportional constant between normal stress and normal strain.
- The modulus of elasticity is a measure of a material's stiffness and is calculated as σ / ε.
- The bigger the modulus of elasticity, the more difficult it is for a material to deform.
Poisson's Ratio
- Poisson's ratio (V) is a measure of the lateral strain to the longitudinal strain of a material.
- Poisson's ratio is calculated as the change in diameter divided by the original diameter.
Material Properties
- Weathering resistance is the ability of a material to endure alternate wet and dry conditions without considerable deformation and loss of mechanical strength.
- Water permeability is the capacity of a material to allow water to penetrate under pressure.
- Frost resistance is the ability of a water-saturated material to endure repeated freezing and thawing with considerable decrease of mechanical strength.
- Fire resistance is the ability of a material to resist the action of high temperature without appreciable deformation and substantial loss of strength.
- Chemical resistance is the ability of a material to withstand the action of acids, alkalis, seawater, and gases.
- Durability is the ability of a material to resist the combined effects of atmospheric and other factors.
- Hardness refers to the property of a material to resist pressing-in or scratch of a sharp object.
- Abrasive resistance refers to the capacity of a material to resist abrasion and is expressed by the abrasion ratio.
Understanding the mechanical properties of building materials, including strength, compressive, tensile, and more. Learn how materials respond to loads and stresses.
Make Your Own Quizzes and Flashcards
Convert your notes into interactive study material.
Get started for free
