1. Effective length of compression member is ________
a) distance between ends of members
b) distance between end point and midpoint of member
c) distance between points of contraflexure
d) distance between end point and centroid of member
Explanation: Effective length of compression member is distance between points of contraflexure. It should be derived from actual length and end conditions.
2. Magnitude of effective length depends upon
a) material of member
b) rotational restraint supplied at end of compression member
c) load applied on member
d) location where member is used
Explanation: Magnitude of effective length depends upon rotational restraint supplied at end of compression member and upon resistance to lateral movement provided.
3. Which of the following is true?
a) greater the effective length, greater the load carrying capacity
b) smaller the effective length, smaller the load carrying capacity
c) smaller the effective length, more the danger of lateral buckling
d) smaller the effective length, smaller the danger of lateral buckling
Explanation: Smaller the effective length of particular compression member, smaller is the danger of lateral buckling and greater is the load carrying capacity.
4.What is the effective length when both ends of compression member are fixed?
a) 0.65L
b) 0.8L
c) L
d) 2L
Explanation: The effective length of compression member when both ends of compression member are fixed is 0.65L (i.e. L/√2), where L is the length of the member.
5. What is the effective length when both ends of compression member are hinged?
a) 0.65L
b) 0.8L
c) L
d) 2L
Explanation: The effective length of compression member when both ends of compression member are hinged is L, where L is the length of the member.
6. What is the effective length when one end of compression member is fixed and other end is free?
a) 0.65L
b) 0.8L
c) L
d) 2L
Explanation: The effective length of compression member when one end is fixed and other end is free is 2L, where L is the length of the member.
7. What is the effective length when one end of compression member is fixed and other end is hinged?
a) 0.65L
b) 0.8L
c) L
d) 2L
Explanation: The effective length of compression member when one end is fixed and other end is hinged is 0.8L, where L is the length of the member.
8. What is slenderness ratio of compression member?
a) ratio of effective length to radius of gyration
b) ratio of radius of gyration to effective length
c) difference of radius of gyration and effective length
d) product of radius of gyration and effective length
Explanation: The tendency of member to buckle is usually measured by its slenderness ratio. Slenderness ratio of member is ratio of effective length to appropriate radius of gyration (λ = kL/r). This is valid only when column has equal unbraced heights for both axes and end condition is same for particular section.
9. Maximum radius of gyration (minimum slenderness ratio) can be obtained by
a) by increasing load
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: Maximum radius of gyration is obtained when material of section is farthest from centroid i.e. away from its axis.
10. The radius of gyration of combined column about axis perpendicular to plane of lacing should be _____ than about axis parallel to plane of lacing.
a) cannot be compared
b) smaller
c) greater
d) equal to
Explanation: The radius of gyration of combined column about axis perpendicular to plane of lacing should be greater than about axis parallel to plane of lacing.