29deep beams

29.3.1 Positive Reinforcement

The tensile reinforcement required to resist positive bending moment in any span of a deep beam shall:

• a) extend without curtailment between supports;

• b) be embedded beyond the face of each support, so that at the face of the support it shall have a development length not less than 0.8 $L_{d}$; where $L_{d}$ is the development length (see 26.2.1), for the design stress in the reinforcement; and

• c) be placed within a zone of depth equal to $0.25 D-0.05 l$ adjacent to the tension face of the beam where $D$ is the overall depth and $l$ is the effective span.

29.3.2 Negative Reinforcement

• a) Termination of reinforcement — For tensile reinforcement required to resist negative bending moment over a support of a deep beam:

1. It shall be permissible to terminate not more than half of the reinforcement at a distance of 0.5 D from the face of the support where D is as defined in 29.2; and
2. The remainder shall extend over the full span.

• b) Distribution-When ratio of clear span to overall depth is in the range 1.0 to 2.5, tensile reinforcement over a support of a deep beam shall be placed in two zones comprising:

1. a zone of depth 0.2 D, adjacent to the tension face, which shall contain a proportion of the

• tension steel given by

$0.5\left(\frac{l}{D}-0.5\right)$

where

1

• = clear span, and

$D=$ overall depth.

2. a zone measuring 0.3 D on either side of the mid-depth of the beam, which shall contain the remainder of the tension steel, evenly distributed.

For span to depth ratios less than unity, the steel shall be evenly distributed over a depth of 0.8 D measured from the tension face.

29.3.3 Vertical Reinforcement

If forces are applied to a deep beam in such a way that hanging action is required, bars or suspension stirrups shall be provided to carry all the forces concerned.

29.3.4 Side Face Reinforcement

Side face reinforcement shall comply with require- ments of minimum reinforcement of walls (see 32.4).