Last edited 10 Oct 2019

Reinforcement detailing

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Contents

[edit] Introduction

Reinforcement detailing plays an important role in construction to resist the collapse of buildings from defective connection or detailing.

Detailing can be done for the following Reinforced Cement Concrete (RCC) members:

  • Slabs with or without openings (rectangular, circular, non-rectangular pyramid slab, triangular slab etc.)
  • Beams with or without openings (shallow and deep beams)
  • Columns with different shapes, such as; rectangular, L, T, circular, octagonal, cross etc.
  • Foundations
  • Gravity loads and lateral loads (particularly for the seismic forces).
  • The rehabilitation and strengthening of damaged structures.

[edit] Do's for detailing

  • Create perfect drawings and if possible label each bar and demonstrate its shape for transparency.
  • Create a bar bending schedule when required.
  • Specify perfect clear cover, nominal cover or effective cover to reinforcement.
  • Determine detailed locations of openings or holes and provide sufficient details for reinforcements around the openings.
  • The grade of steel should be mentioned in the drawing.
  • Deformed bars should not contain hooks at their ends.
  • Show enlarged details at corners, junctions of walls, beams and column joints.
  • Congestion of bars should not occur at points where members overlap.
  • For bundled bars, lapped splice of bundled bars should be created by splicing one bar at a time; such separate splices inside the bundle should be staggered.
  • Ensure that hooked and bent up bars are arranged and contain sufficient concrete protection.
  • Specify all extension, construction and contraction joints on plan and provide details for such joints.
  • The position of construction joints should remain at the point of minimum shear approximately at mid or adjacent to the mid points. It should be developed vertically and not in a sloped manner.

[edit] Do's for beam and slab reinforcement detailing

  • When splices are arranged in bars, they should remain out of the sections of maximum stresses as far as possible and should be staggered.
  • When the depth of beams surpass 750 mm in case of beams devoid of torsion and 450 mm with torsion provide face reinforcement according to IS456-2000.
  • Deflection in slabs/beams is minimised with the compression reinforcement.
  • Only closed stirrups are recommended for transverse reinforcement. For members susceptible to torsion and for members susceptible to reversal of stresses similar to seismic forces.
  • To adapt bottom bars, secondary beams should be created shallower than primary beams, at least by 50 mm.

[edit] Do's for column reinforcement detailing

[edit] Do not's general

  • Reinforcement should not extend over an expansion joint and the break among the sections should be finished.
  • Flexural reinforcement should not preferably be discontinued in a tension zone.
  • Bars greater than 36 mm dia should not be bundled.
  • Lap splices should not be utilised for bars greater than 36 mm dia. except where welded.
  • When dowels are used, their diameter should not go beyond the diameter of the column bars in excess of 3 mm.
  • When bent up bars are used, their participation towards shear resistance should not surpass 50% of the total shear to be countered. Single bent up bars alias cranked should not be used in earthquake resistance structures.

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