The modular ratio ‘m’ of a concrete whose permissible compressive stress is ‘C’, may be obtained from the equation.

When an open coiled helical compression spring is subjected to an axial compressive load, the maximum shear stress induced in the wire is (where D = Mean diameter of the spring coil, d = Diameter of the spring wire, K = Wahl's stress factor and W = Axial compressive load on the spring)

A

$$\frac{{{\text{WD}}}}{{\pi {{\text{d}}^3}}} \times {\text{K}}$$

B

$$\frac{{2{\text{WD}}}}{{\pi {{\text{d}}^3}}} \times {\text{K}}$$

C

$$\frac{{4{\text{WD}}}}{{\pi {{\text{d}}^3}}} \times {\text{K}}$$

D

$$\frac{{8{\text{WD}}}}{{\pi {{\text{d}}^3}}} \times {\text{K}}$$

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 C is creep coefficient, f is original pre-stress in concrete, m is modular ratio, E is Young's modulus of steel and e is shrinkage strain, the combined effect of creep and shrinkage is:

A

(1 - C) mf - eE

B

(C - 1) mf + eE

C

(C - 1) mf - eE

D

(1 - C) mf + eE

If ‘A’ is the sectional area of a pre-stressed rectangular beam provided with a tendon pre-stressed by a force ‘P’ through its centroidal longitudinal axis, the compressive stress in concrete, is

A

$$\frac{{\text{P}}}{{\text{A}}}$$

B

$$\frac{{\text{A}}}{{\text{P}}}$$

C

$$\frac{{\text{P}}}{{2{\text{A}}}}$$

D

$$\frac{{2{\text{A}}}}{{\text{P}}}$$

In a singly reinforced beam, if the permissible stress in concrete reaches earlier than that in steel, the beam section is called

A

Under-reinforced section

B

Over reinforced section

C

Economic section

D

Critical section

The change in length due to a tensile or compressive force acting on a body is given by (where P = Tensile or compressive force acting on the body, $$l$$ = Original length of the body, A = Cross-sectional area of the body and E = Young's modulus for the material of the body)

A

$$\frac{{{\text{P}}l{\text{A}}}}{{\text{E}}}$$

B

$$\frac{{{\text{P}}l}}{{{\text{AE}}}}$$

C

$$\frac{{\text{E}}}{{{\text{P}}l{\text{A}}}}$$

D

$$\frac{{{\text{AE}}}}{{{\text{P}}l}}$$

The ultimate tensile stress for mild steel is __________ the ultimate compressive stress.

A

Equal to

B

Less than

C

More than

D

None of these

The ultimate tensile stress of mild steel compared to ultimate compressive stress is

A

Same

B

More

C

Less

D

Unpredictable

In working stress design, permissible bond stress in the case of deformed bars is more than that in plain bars by

A

10%

B

20%

C

30%

D

40%

The length of the lap in a compression member is kept greater than bar diameter x (Permissible stress in bar / Five times the bond stress) or

A

12 bar diameters

B

18 bar diameters

C

24 bar diameters

D

30 bar diameters

The modular ratio ‘m’ of a concrete whose permissible compressive stress is ‘C’, may be obtained from the equation.

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