This set of Design of RC Structures Multiple Choice Questions & Answers (MCQs) focuses on “Axially Loaded Columns – Spirally Reinforced Columns”.
1. The ratio of volume of the helical reinforcement to the volume of the core should not be less than_____________
a) .36((Ag/Ak)-1)fck/fy
b) .36(Ag/Ak)fck/fy
c) .36(Ak/Ag)fck/fy
d) .36(Ag/Ak)fy/fck
View Answer
Explanation: According to the clause 39.4.1 we got the guidelines for helical reinforcement in column. The volume of the helical reinforcement to the volume of the core should not be less than .36((Ag/Ak)-1)fck/fy where,
Ag = Gross area of the section
Ak = Area of core of the helically reinforced column
fck = Characteristic strength of the concrete
fy = characteristic strength of helical reinforcement (not more than 415).
2. The helically reinforced column is more desired in earth-quake prone area than column with lateral ties.
a) True
b) False
View Answer
Explanation: The helically reinforced column has a higher characteristic strength and ductility as compared to that with lateral ties. Therefore the helically reinforced columns are more effective in earthquake prone areas.
3. What is the range of pitch for a helically reinforced column?
a) 25-50mm
b) 20-40mm
c) 25-75mm
d) 50-80mm
View Answer
Explanation: According to recommendation of IS 456:2000 the pitch of the helical reinforcement should neither be less than 25mm nor be more than 75mm. Again it should neither be more than one sixth of the diameter of the column nor be less than three times of the reinforcement bars.
4. The maximum load capacity of the helical reinforced column is more than that with lateral ties.
a) True
b) False
View Answer
Explanation: IS 456:2000 gives (clause 39.4.2) the load capacity of helical reinforcement is 1.05 times of the column with lateral ties. Again it may be proven from the graphical representation.
5. Which is equivalent to the spacing of the tied reinforcement?
a) Diameter of the helical reinforcement
b) Perimeter of the helical reinforcement
c) Range of the helical reinforcement
d) Pitch of the helical reinforcement
View Answer
Explanation: As the helical reinforcement is not separated from each other there is no spacing.
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