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The design yield stress of steel according to IS: 456-1978 is (where fy is the characteristic yield strength of steel)
A
0.37 fy
B
0.57 fy
C
0.67 fy
D
0.87 fy
Correct Answer:
0.87 fy
The design stress, which is more than the damaging stress, is the least unit stress that will render a member unfit for service before the end of its normal life. The design stress factor or factor of safety indicates the margin between design stress and the __________ stress.
A
Working
B
Damaging
C
Allowable
D
None of these
If the specimen is deformed plastically beyond the yield stress in one direction, e.g., tension and then after unloading it is loaded in the opposite direction, e.g., compression, it is found that the yield stress is less than the original yield stress. This dependence of yield stress on direction loading is called ____________
A
bauschinger effect
B
strain hardening
C
residual stress
D
nabarro–herring effect
Identify the correct statements from the following:
P. 0.2% yield strength of a material implies 0.2% of the yield strength.
Q. Von-Misses yield criterion implies that yielding occurs when the distortion energy reaches a critical value.
R. Radius of the cylinderical Von-Misses yield surface increases as the grain, size of a single phase material decreases.
S. Tresca's yield criterion gives a circular cylinderical surface in the space of the three principal stresses.
A
P, Q
B
Q, R
C
P, R
D
Q, S
Examine the following statements :
i) Factor of safety for steel should be based on its yield stress,
ii) Factor of safety for steel should be based on its ultimate stress,
iii) Factor of safety for concrete should be based on its yield stress,
iv) Factor of safety for concrete should be based on its ultimate stress.
The correct statements are
A
(i) and (iii)
B
(i) and (iv)
C
(ii) and (iii)
D
(ii) and (iv)
Elastic failure of a material occurs, when the tensile stress equals yield strength, yield point or the elastic limit. Also, the elastic failure occurs according to maximum strain theory, when the maximum tensile strain equals (where, $$\sigma $$ = yield strength and E = modulus of elasticity)
A
E
B
$$\sigma $$
C
$$\frac{\sigma }{{\text{E}}}$$
D
$$\frac{{\text{E}}}{\sigma }$$
Tresca or maximum-shear stress criteria assumes that yielding occurs when the maximum shear stress reaches a value of the shear stress in the uniaxial tension test. Assume the principal stress being σ1, σ2, σ3 where σ1 is largest, and σ3 is the smallest principal stresses. Find the value of minimum shear stress to cause yielding, given that yield stress in tension is equal to σo?
A
τ = σo
B
τ = σo/2
C
τ = σo/3
D
τ = σo/4
From an alloy, two specimens are machined and tested separately under tension and compression. The engineering stress-strain curves as well as the true stress-true strain curves for tension and compression are plotted in the same diagram. Identify the correct statements:
P. The engineering stress-strain curves in tension and compression are identical.
Q. The true stress-true strain curve in compression is lower than the true stresstrue strain curve in tension due to Bauschinger effect.
R. The true stress-true strain curve in tension is above the corresponding engineering stress-strain, curve.
S. The true stress-true strain curve in tension and compression are identical.
A
P, Q
B
Q, R
C
Q, S
D
R, S
According to principal stress theory, which option represents the correct relation between yield strength in shear (YSS) and the yield strength in tension (YST)?
A
YSS=0.5YST
B
YSS=0.577YST
C
YST=0.5YSS
D
YST=0.577YSS
For a given component, the alternating stress is equal to 250 MPa, Mean stress is 100 MPa, and the ultimate tensile strength is 500 MPa. Find the yield strength of the material according to Goodman’s approach?
A
3125.5 MPa
B
312.5 MPa
C
5215.3 MPa
D
521.5 MPa
For a given component, the alternating stress is equal to 250 MPa, Mean stress is 100 MPa, and the ultimate tensile strength is 500 MPa. Find the yield strength of the material according to the Gerber’s approach?
A
521 MPa
B
694 MPa
C
45 MPa
D
55 MPa