Prestressed Concrete Structures Multiple Choice Questions on “Codes of Practice”.
1. Which one of the following is the Indian standard regarded to the limit state of deflection?
a) IS: 1443-1950
b) IS: 1343-1980
c) IS: 1514-1941
d) IS: 1600-1948
Answer: b
Clarification: It is the general practice in most of the codes to safeguard against excessive deflections under serviceability limit states, either indirectly by prescribing a minimum span to depth ratio for the member or directly by specifying a maximum permissible deflection expressed as a fraction of the span and recommendations of Indian standard code with regard to the limit state of deflections is IS: 1343-1980.
2. The final deflection due to all loads including the efforts of temperature, creep and shrinkage should normally exceed span up to __________
a) Span/250
b) Span/300
c) Span/500
d) Span/800
Answer: a
Clarification: The final deflection due to all loads including the effects of temperature, creep and shrinkage should normally not exceed span/250 is the first recommendations made by IS: 1343-1980 with regard to the limit state of deflection.
3. The deflection including the effects of temperature, creep and shrinkage occurring after the erection should not normally exceed __________
a) Span/400
b) Span/350
c) Span/140
d) Span/100
Answer: b
Clarification: The deflection including the effect of temperature, creep and shrinkage occurring after the erection of partitions and the application of finishes should not normally exceed span/350 whichever is less, creep is directly proportional to the stresses but above this value it increases more rapidly.
4. If the finishes are to be applied to the prestressed concrete members, the total upward deflection should not exceed __________
a) Span/300
b) Span/450
c) Span/150
d) Span/350
Answer: a
Clarification: If finishes are applied to the prestressed concrete members, the total upward deflection should not exceed span/300, unless uniformity of chamber between adjacent units can be ensured, span/350 or 20mm whichever is less for non brittle partitions or finishes.
5. The British code specifies a maximum deflection limit of span which the sag in the member usually become noticeable is?
a) Span /130
b) Span/250
c) Span/200
d) Span/150
Answer: c
Clarification: The British code (BS: 8110-1985) specifies a maximum deflection limit of span/250 beyond which the sag in a member will be usually become noticeable and to prevent damage to non-structural elements, the code recommends that the deflection after the installation of finishes & partitions should not exceed the span/500 or 20mm whichever is less for brittle members.
6. The type of deflection of not supporting and non structural elements of flat roofs is?
a) Large deflection
b) Immediate deflection
c) Small deflection
d) Edge deflection
Answer: c
Clarification: Floors roofs not supporting and not attached to non structural element likely to be damaged by large deflection such deflection is considered as immediate deflection due to the live load, deflection limitations are given as (span/180).
7. The floors not supporting and not attached to non structural elements are damaged by __________
a) Large deflection
b) Column deflection
c) Span deflection
d) Beam deflection
Answer: a
Clarification: Floors not supporting and not attached to non structural element likely to be damaged by large deflections and are carried by immediate deflection due to live load and deflection limitations are given as (span/360).
8. The FIP-1984 limits for total deflection below the level of supports up to __________
a) Span/200 to Span/300
b) Span/150 to Span/250
c) Span/100 to Span/50
d) Span/175 to Span/280
Answer: a
Clarification: The FIP-1984 recommends the following suitable deflection limits for floors, roofs and the other horizontal members in building as total deflection below the level of supports is Span/200 to Span/300.
9. The FIP-1984 limits for deflection that occurs after addition of partitions up to __________
a) Span/200 to Span/300
b) Span/250 to Span/350
c) Span/500 to Span/1000
d) Span/170 to Span/320
Answer: c
Clarification: The FIP-1984 recommends the following suitable deflection limits for floors, roofs and the other horizontal members in building limits for deflection that occurs after addition of partitions up to:
Span/500 to Span/1000.
10. The French code limits the deflection of members carrying masonry and partition walls up to __________
a) Span/600
b) Span/400
c) Span/500
d) Span/700
Answer: c
Clarification: The French code limits the deflection of members carrying masonry and partition walls to span/500, which is the total increase in deflection due to short term and sustained loads over the instantaneous deflection due to self weight.