Design of Steel Structures Multiple Choice Questions on “Factors affecting Lateral Stability”.
1. Which of the following does not affect lateral stability?
a) cross sectional shape
b) support conditions
c) type of loading
d) height of building
Answer: d
Clarification: The factors affecting lateral stability are cross sectional shape, support conditions, effective length, level of application of transverse loads.
2. Which of the following statement is correct?
a) I-section has high torsional stiffness
b) Closed section has high torsional stiffness
c) Closed section has less stiffness
d) Hollow circular tube has more efficiency as flexural member
Answer: b
Clarification: I-section with the larger in-plane bending stiffness does not have matching stability. in contrast, closed sections such as tubes, boxes and solid shafts have high torsional stiffness, often high as 100 times that of an open section.
3. Which of the following statement is not correct?
a) Hollow circular tube has more efficiency as flexural member
b) Hollow circular tube has lesser efficiency as flexural member
c) It is the most efficient shape for torsional resistance
d) It us rarely used as a beam element
Answer: a
Clarification: Hollow circular tube is the most efficient shape for torsional resistance, but is rarely employed as beam element because of difficulties encountered in connecting it to other members and lesser efficiency as a flexural member.
4. Open cross sections have major part of material distributed
a) is not distributed
b) on the centroid
c) towards centroid
d) away from centroid
Answer: d
Clarification: In open cross sections ( I and channel sections), major part of material is distributed at the flanges, i.e. away from their centroids, to improve their resistance to in-plane bending stresses.
5. The effective length factor is _____ for beams flanges fully restrained
a) 1
b) 0.5
c) 0.75
d) 1.5
Answer: b
Clarification: The effective length factor K is 0.5 theoretically for flanges fully restrained. But for design purpose, it may be taken as 0.7.
6. The effective length of compression flange of simply supported beam not restrained against torsion at ends is
a) 1.2 L
b) 1.0 L
c) 0.8 L
d) 0.5 L
Answer: a
Clarification: The effective length of compression flange of simply supported beam not restrained against torsion at ends is 1.2 L, where L is span length.
7. Effective length of compression flanges at the ends unrestrained against lateral buckling is
a) 1.5 L
b) 0.85 L
c) 0.5 L
d) L
Answer: d
Clarification: Effective length of compression flanges at the ends unrestrained against lateral buckling (i.e. free to rotate in plan) is L, where L is length of span.
8. Effective length of compression flanges at the ends partially restrained against lateral buckling is
a) 1.75 L
b) 1.0 L
c) 0.85 L
d) 0.5 L
Answer: c
Clarification: Effective length of compression flanges at the ends partially restrained against lateral buckling (i.e. free to rotate in plane in the bearings) is 0.85 L, where L is length of span.
9. Restraint against torsion can be provided by
(i) web cleats, (ii) bearing stiffeners acting together with bearing of beam, (iii)lateral end frames to ends of compression flanges
a) i only
b) i and ii
c) ii and iii
d) i, ii and iii