This set of Design of Steel Structures Multiple Choice Questions & Answers (MCQs) focuses on “Deflection & Holes in Beams”.
1. Which of the following may not occur due to excessive deflection?
a) ponding problem in roofs
b) misalignment of supporting machinery
c) cracking of plaster ceilings
d) twisting of beam
View Answer
Explanation: Excessive deflection may cause cracking of plaster ceilings, misalignment of supporting machinery and cause excessive vibration, ponding problem in roofs, etc. Hence deflection in beam needs to be limited.
2. What is ponding?
a) excessive deflection of flat roof resulting in accumulation of rainwater
b) excessive deflection of flat roof not resulting in accumulation of rainwater
c) small deflection of flat roof resulting in accumulation of rainwater
d) small deflection of flat roof not resulting in accumulation of rainwater
View Answer
Explanation: Excessive deflection of flat roof resulting in accumulation of water during rainstorms is called ponding and it causes damage to the roof material.
3. Deflection can be reduced by
a) proving less restraints
b) increasing span
c) increasing depth of beam
d) decreasing depth of beam
View Answer
Explanation: Deflection can be reduced by increasing depth of beam, reducing the span, providing greater end restraints or by other means such as providing camber.
4. Beam deflection is not a function of
a) loading
b) span
c) length of column
d) geometry of cross section
View Answer
Explanation: Beam deflection is a function of loading, span, modulus of elasticity and geometry of cross section. Small deflections of beams do not cause structural problems in general except for discomfort to the users. But excessive deflections may lead to crack in plaster or ceilings and may damage material attached to or supported by beams.
5. What is the maximum vertical deflection in industrial building for purlins and girts subjected to live load/wind load for elastic cladding?
a) span/150
b) span/180
c) span/250
d) span/100
View Answer
Explanation: The maximum deflection in industrial building for purlins and girts subjected to live load/wind load for elastic cladding is span/150 and for brittle cladding is span/180.
6. What is the maximum vertical deflection in other buildings (other than industrial buildings)for floor subjected to live load and elements not susceptible to cracking?
a) span/150
b) span/180
c) span/300
d) span/100
View Answer
Explanation: The maximum deflection in other buildings (other than industrial buildings) for floor subjected to live load and elements not susceptible to cracking is span/300.
7. What is the maximum vertical deflection in other buildings (other than industrial buildings) for floor subjected to live load and elements susceptible to cracking?
a) span/150
b) span/360
c) span/300
d) span/100
View Answer
Explanation: The maximum deflection in other buildings (other than industrial buildings) for floor subjected to live load and elements susceptible to cracking is span/360.
8. What is the maximum lateral deflection in other buildings (other than industrial buildings) subjected to wind load and for brittle cladding?
a) height/300
b) height/250
c) height/100
d) height/500
View Answer
Explanation: The maximum lateral deflection in other buildings (other than industrial buildings) subjected to wind load and for brittle cladding is height /500 and for elastic cladding is height/300.
9. What is the maximum vertical deflection for a cantilever member in other buildings (other than industrial buildings) subjected to live load and elements not susceptible to cracking?
a) span/150
b) span/180
c) span/300
d) span/100
View Answer
Explanation: The maximum vertical deflection for a cantilever member in other buildings (other than industrial buildings) subjected to live load and elements not susceptible to cracking is span/150 and for elements susceptible to cracking is span/180.
10. What is the maximum lateral deflection of column/frame in industrial buildings subjected to crane load plus wind load and for brittle cladding?
a) height/300
b) height/250
c) height/400
d) height/500
View Answer
Explanation: The maximum lateral deflection of column/frame in industrial buildings subjected to crane load plus wind load and for brittle cladding (pendant operated) is height/400 and for elastic cladding (cab operated) is height/200.
11. The strength of steel beam depends on
a) strength of tension flange
b) strength of compression flange
c) strength of web
d) does not depend on strength of section
View Answer
Explanation: The strength of steel beam depends on the strength of compression flange. An open hole in the compression flange affects the strength of steel beam more than a hole in tension flange.
12. A hole in flange of beam causes
a) increase in stress
b) decrease in stress
c) makes the stress to half
d) does not affect the stress
View Answer
Explanation: A hole in flange of beam causes an increase in stress. If the hole in compression flange contains rivet or bolt, the strength reduction is lessened as fastener can transmit compression.
13. Holes in beam webs should be placed at ____ and in flanges it should be placed at ________
a) high shear, high bending moment
b) high bending moment, high shear
c) low bending moment, low shear
d) low shear, low bending moment
View Answer
Explanation: Holes in beam webs have less effect on flexural strength than holes in the flanges. Holes in beam webs should be placed only at sections of low shear. In the flanges, the holes should be cut at points of low bending moment. If this is not possible, the effect of the holes should be accounted for design.
14. The strength of the beams with openings may be governed by plastic deformations due to
a) moment only
b) shear only
c) both moment and shear
d) does not depend on moment or shear
View Answer
Explanation: The strength of the beams with openings may be governed by plastic deformations due to both moment and shear at the openings. The strength realised will depend upon the interaction between moment and shear. The reduction in moment capacity at the openings is small while the reduction in shear capacity may be significant.
15. Which of the following are correct regarding design of beams with openings?
a) web opening should be away from support by twice the beam depth
b) hole should be eccentrically placed in web
c) hole should not be placed within middle one third of the span
d) clear spacing between openings should be less than beam depth
View Answer
Explanation: General guidelines for design of beams with openings are as follows : (i)The hole should be centrally placed in web and eccentricity should be avoided, (ii) The best location for the opening is within the middle one third of the span, (iii) Web opening should be away from support and it should be away by twice the depth of beam, (iv) Clear spacing between openings should be more than depth of beam.
16. Which of the following are not correct regarding design of beams with openings?
a) diameter of circular opening should be restricted to 0.5D
b) for rectangular stiffened openings depth should be less than 0.7D and length less 2D
c) for rectangular unstiffened openings, depth should be less than 0.5D and length less than 1.5D
d) point load should be applied within a distance d from adjacent opening
View Answer
Explanation: General guidelines for design of beams with openings are as follows : (i) The diameter of circular opening should be restricted to 0.5D, where D is depth of beam, (ii) For rectangular unstiffened openings, depth should be less than 0.5D and length less than 1.5D, where D is depth of beam (iii) For rectangular stiffened openings, depth should be less than 0.7D and length less 2D, where D is depth of beam (iv) Point loads should not be applied within a distance d from the adjacent opening.
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