Structure Engineering notes for GATE and PSUs - part 6

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Are you ready for next part of our preparation notes?
Here we go:

• According to IS:456: 1978, the column or the strut is the member whose effective length is greater than 4 times the least lateral dimenstion.
• According to IS:456:1978, minimum slenderness ratio for a short column is less than 12.
• Lap length in compression shall not be less than 24 times diameter of the bar.
• The minimum cover in slab should neither be less than diameter of the bar nor less than 15 mm.
• For a longitudinal reinforcing bar in a column, the minimum cover shall neither be less than diameter of the bar nor less than 40 mm.
• The ratio of the diameter of the reinforcing bars and slab thickness is 1/8.
• According to IS:456-1978, the maximum reinforcement in a column in a column is 6%.
• The percentage of reinforcement in case of slabs, when high strength deformed bars are used is not less than 0.12.
• Minimum cross sectional area of longitudinal reinforcement  in a column is 0.8%.
• Spacing of longitudinal bars measured along the periphery of column should not exceed 300 mm.
• Reinforcing bars in columns should not be less than 12 mm.
• Higher slump and higher compaction factor shows higher workability.
• Minimum pitch of transverse reinforcement in a column is lesser of 

1. the lease lateral dimension of the member
2. Sixteen times the smallest diameter of the longitudinal reinforcement bar to be tied
3. forty eight times the diameter of the transverse reinforcement.

• Maximum distance between expansion joints in structures as per IS:456-1978 is 45 m.
• A continuous beam is deemed to be a deep beam when the ratio of effective span to overall depth (l/D) is less than 2.5.
• Critical section for shear in case of flat slabs is at a distance of d/2 from the periphery of column/capital/drop panel.
• Minimum thickness of load bearing RCC wall should be 100 mm.
• If the storey height is equal to length of RCC wall, the percentage increase in strength is 10.
• In reinforced concrete footing on soil, the minimum thickness at edge should not be less than 150 mm.
• The slab is designed as one way if the ratio of long span to short span is greater than 2.
• Ratio of permissible stress in direct compression and bending compression is less than 1.
• A higher modular ratio shows a lower compression strength of concrete.
• The average permissible stress in bond for plain bars in tension is increased by 25% for bars in compression.
• In working stress design, permissible bond stress in the case of deformed bars is more than that in plain bars by 40%.
• The main reason for providing numbers of reinforcing bars at a support in a simply supported beam is to resist in that zone the bond stress.

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