21) Which one of the following is a compression member ?
a) Purlin
b) Boom
c) Girt
d) Tie
22) If span of a roof truss is between 15–30 m, preferable spacing is
(a) 3.0 to 4.5 m
(b) 4.5 to 6.0 m
(c) 6 to 8 m
(d) 10–12 m
23) The slenderness ratio of lacing bars should not exceed
a) 100
b) 120
c) 145
d) 180
24) For spacing of trusses 3 to 4 m, purling used are
(a) angle iron with outstanding leg at top
(b) angle iron with outstanding leg at bottom
(c) channel sections
(d) I-sections
25) The heaviest I section for same depth is
a) ISMB
b) ISLB
c) ISHB
d) ISWB
26) In steel bridges, for span less than 9 m and class AA loading for wheeled vehicles, the impact factor is taken as
a) 20%
b) 25%
c) 30%
d) 35%
27) In a truss design, snow load need not be considered when roof is steeper than
a) 100
b) 150
c) 300
d) 450
28) To minimize the total cost of a roof truss, the ratio of the cost of truss to the cost of purlins shall be
a) 1
b) 2
c) 3
d) 4
29) What is the number of plastic hinges formed if an indeterminate beam with redundancy R is to become determinate ?
a) R – 1
b) R
c) R + 1
d) R + 2
30) At the location of a plastic hinge,
a) radius of curvature is infinite
b) curvature is infinite
c) moment is infinite
d) flexible stress in infinite