Spacer bars in Beams
Where there are two or more rows of bars, the bars shall be vertically in line and the minimum vertical distance between the bars shall be 15 mm, two-thirds the nominal maximum size of coarse aggregate or the maximum size of bar whichever is the greatest. The vertical distance may be maintained by providing spacer bars placed 0.9 m to 1.2 m apart from one another throughout the length of the beam.
Reinforcement in Slab
- In case of a slab simply supported at its ends or at end support (i.e. roof slab built into walls) and carrying a uniformly distributed load alternative bars are bent up from a point 1/7 the effective span away from the support to resist the small negative bending moment (not less than WI/24) that may occur in the slab due to its partial fixity in the wall.
- In case where a slab is continuous over several spans and the condition of the slab at every support is the same, somewhere between perfect fixity and perfect freedom, generally alternative bottom bars (i.e. 50%) from each side of the support are bent up from a point 1/5th span away from the centre of support and the same bar is carried at top of counteract negative bending moment into the next span to a point 1/4th span away from the centre of support, the remaining 50% of bottom straight bars are carried into a length 1/10th of the span from each side of the support provided development length is satisfied.
- In slabs, whether double or multiple layers of reinforcement are provided, the distances between the layers may be maintained by the method of support bars.
