# Design of Steel Structures Questions and Answers – Behaviour of Compression Members & Types of Sections

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This set of Design of Steel Structures Questions and Answers for Entrance exams focuses on “Behaviour of Compression Members & Types of Sections”.

1. For very short compression member
a) failure stress will be greater than yield stress
b) failure stress will be less than yield stress
c) failure stress will equal yield stress
d) failure stress will be twice the yield stress

Explanation: For very short compression members, the failure stress will the equal yield stress and no buckling will occur.

2. The length of member should be _________ for a short column
a) L ≤ 88.5r
b) L ≥ 88.5r
c) L ≥ 125r
d) L > 150r

Explanation: For a member to be classified as short column, length of member should be L ≤ 88.5r , where r is radius of gyration. The slenderness ratio of column defines the column as short or long column.

3. Long compression members will ______
a) not buckle
b) buckle inelastically
c) buckle plastically
d) buckle elastically

Explanation: Long compression members will buckle elastically where axial buckling stress remains below proportional limit.

4. Which of the following is true about intermediate length compression members?
a) members will fail by yielding only
b) members will fail by both yielding and buckling
c) their behaviour is elastic
d) all fibres of the members will be elastic during failure

Explanation: For intermediate length compression members, some fibres would have yielded and some fibres will still be elastic. They will fail by both yielding and buckling and their behaviour is said to be inelastic.

a) load at which member will not deform axially
b) load at which member deforms laterally
c) load at which member deforms axially
d) load at which member will not deform axially

Explanation: Large deformation is possible only when fc reached the yield stress. At this stage the member deforms axially. The value of axial force at which this deformation occurs is called squash load.

6. Which of the following is not a parameter for decrease in strength of slender member?
b) initial lack of straightness
c) residual stress
d) variation of material properties

Explanation: The decrease in strength of slender member is due to following parameter : imperfections- initial lack of straightness, accidental eccentricities of loading, residual stress, and variation of material properties over the cross section.

7. Which of the following is property of compression member?
a) member must be sufficiently rigid to prevent general buckling
b) member must not be sufficiently rigid to prevent local buckling
c) elements of member should be thin to prevent local buckling
d) elements of member need not prevent local buckling

Explanation: Member must be sufficiently rigid to prevent general buckling in any possible direction, and each element of member must be thick enough to prevent local buckling.

8. How can moment of inertia be increased?
b) by spreading material of section towards its axis
c) by spreading material of section away from its axis
d) by spreading material of section at its axis

Explanation: Most important property of section in compression member is radius of gyration and thus moment of inertia. it can be increased by spreading material of section away from its axis.

9. Which is an ideal section for compression member?
a) one having different moment of inertia about any axis through its centre of gravity
b) one having same moment of inertia about any axis through its centre of gravity
c) one having larger length
d) one made up of costly material

Explanation: Ideal section is the one which has same moment of inertia about any axis through its centre of gravity.

10. Rods and bars are recommended when length is ___________
a) greater than 4m
b) greater than 5m
c) greater than 3m
d) less than 3m

Explanation: Rods and bars withstand very little compression when length is more. Hence these are recommended for lengths less than 3m only.

11. Which of the following is true about tubular section?
a) tubes have low buckling strength
b) tubes have same radius of gyration in all direction
c) tubes do not have torsional resistance
d) weight of tubular section is more than the weight required for open profile sections

Explanation: Tubes have same radius of gyration in all direction. They have high buckling strength and have excellent torsional resistance. Weight of tubular section is less than one half the weight required for open profile sections.

12. Which of the following statement is true?
a) unequal angles are desirable over equal angles
b) least radius of gyration of equal angle is less than that of unequal angle for same area of steel
c) single angle sections are suitable for long lengths
d) least radius of gyration of single angle section is small compared to channel and I-sections

Explanation: Equal angle are desirable and economical over unequal angles because least radius of gyration of equal angle is greater than that of unequal angle for same area of steel. Single angle sections are not suitable for long lengths. Least radius of gyration of single angle section is small compared to channel and I-sections.

Sanfoundry Global Education & Learning Series – Design of Steel Structures. 