Understanding Side Face Reinforcement in Beams (IS:456-2000)

Side face reinforcement in reinforced concrete beams is provided to control cracking caused by shrinkage and temperature effects, especially in deep webs. This reinforcement helps distribute the tensile stresses that can develop perpendicular to the main flexural reinforcement in deep beams.

IS:456-2000 Provision for Side Face Reinforcement

According to the Indian Standard Code of Practice for Plain and Reinforced Concrete, IS:456-2000, specific guidelines are provided for the provision of side face reinforcement. Clause 26.5.1.3 of IS:456-2000 deals with the requirements for deep beams or beams with large web depths.

The code stipulates that:

• When the depth of the web in a beam exceeds 750 mm, side face reinforcement should be provided along the two faces of the beam.
• This reinforcement is required to control potential cracking in the deep web sections.
• The total area of this reinforcement should be not less than 0.1% of the web area.
• This reinforcement should be distributed equally on both faces of the web.
• The spacing of the side face reinforcement should not exceed 300 mm or the web thickness, whichever is less.

Therefore, based on the provisions of IS:456-2000, side face reinforcement is mandatory when the depth of the web exceeds the specified limit.

Determining the Threshold Web Depth

The question asks for the depth of the web beyond which side face reinforcement must be provided as per IS:456-2000. Referring to Clause 26.5.1.3, the threshold depth is clearly mentioned.

The options provided are:

• 350 mm
• 550 mm
• 650 mm
• 750 mm

The code specifies that side face reinforcement is required when the web depth exceeds 750 mm.

Thus, the correct answer corresponds to the web depth exceeding 750 mm.

Understanding this clause is crucial for the design and detailing of reinforced concrete beams, particularly those with significant depths, to ensure durability and serviceability by controlling shrinkage and temperature cracks.

Conclusion

As per IS:456-2000, side face reinforcement is required in a beam when the depth of the web exceeds 750 mm.