Day 29-Oct 17-worksheet-PWD-Working stress method&PSC intro.

The modular ratio used in the working stress method partially accounts for the effect of —

• Shrinkage of concrete

• Elastic shortening

• Creep of concrete

• Fatigue of steel

For M 25 concrete, the permissible bending compressive stress σ_cbc as per WSM is —

• 6 N/mm²

• 8.5 N/mm²

• 9 N/mm²

• 11.5 N/mm²

In prestressed concrete, the force is transmitted to concrete by bond between steel and concrete in —

• Post-tensioned system

• Pre-tensioned system

• Centrally tensioned system

• Load-balanced system

A reinforced concrete column has 1 % steel and modular ratio = 10. The ratio of load carried by steel to that carried by concrete (Ps/Pc) is —

The critical depth of neutral axis for Fe 415 steel under WSM is —

• 0.40 d

• 0.289 d

• 0.253 d

• 0.33 d

In WSM, the stress–strain curve of concrete is assumed to be linear up to the permissible stress.

• True

• False

The modular ratio (m) decreases as the grade of concrete increases.

• True

• False

In direct tension, the permissible stress in concrete for M 20 grade =

Prestressing in which tendons are tensioned after concrete has hardened is called

For Fe 500 steel, the permissible stress in tension (σst) =