Steel Structures - Plastic Theory

1. The strength of a material is related to
(a) yield stress
(b) average yield stress
(c) proof stress
(d) stress at fracture

2. The strength of materials which do not have distinct yield point, is specified in terms of
(a) plastic stress
(b) 0.2% average yield stress
(c) 0.2% proof stress
(d) 0.2% yield stress

3. The stress level at which a residual strain of 0.2% is left over after unloading, is called
(a) 0.2% yield stress
(b) 0.2% average yield stress
(c) 0.2% stress at plastic stage
(d) 0.2% proof stress

4. Pick the wrong statement
(a) In plastic theory of structures strain hardening is ignored.
(b) In plastic analysis it is assumed that the material is perfectly elastic-plastic or rigid-plastic
(c) theory of elasticity can be used for structural analysis at time of failure
(d) At ultimate load, the stresses at several points exceed the elastic limit

5. The method of plastic design of steel structure is also known as
(a) limit design method
(b) collapse method of design
(c) ultimate design
(d) all the above

6. Ultimate load design method is preferred over elastic theory because of
(a) simplicity
(b) economy
(c) both (a) and (b)
(d) none of these

7. Which one of the following conditions, both elastic and plastic methods of analysis or indeterminate structures have to satisfy?
(a) yield condition
(b) mechanism condition
(c) equilibrium
(d) compatibility of deformation (GATE 1995)

8. The approximate ratio of plastic moment capacity of a rolled steel beam section to the yield moment capacity of the section is
(a) 0.85
(b) 1.00
(c) 1.10
(d) 1.25 (IES 1992)

9. If Y-Y is the centroidal axis of a T-beam section subjected to plastic moment Mp, the neutral axis lies
(a) above line Z-Z
(b) between lines Y-Y and Z-Z
(c) between lines X-X and Y-Y
(d) below the line X-X (GATE 1996)

10. Pick the wrong statement regarding assumptions made in plastic analysis of beams
(a) increase in strength due to strain hardening is neglected
(b) there is no axial load on beam
(c) shear strains are taken into account
(d) material obeys ideal stress-strain relationship