Important points related to the Design of Beams
In this article, I’m going to discuss some important points related to the design of RCC beams which are going to be very much helpful to all of you.
- As per IS 13920-2016, Cl 6.1.1; For beams of rectangular cross-section, It shall always be preferred to have a Width to Depth ratio greater than 0.3. i.e., If Bw is the width of beam and D be its depth;
Bw/D > 0.3
- While deciding the size of an RCC beam, The minimum width shall be considered as 200mm.
- The depth of a beam shall not be more than 1/4th of its clear span. e.g, If D is the depth of a beam and L its clear span, then;
D ≤ L/4
However, for calculating the depth of a beam using the thumb rule, we use the formula; Depth of Beam = L/10 to L/12
Where L = Clear span of the beam. By the term ‘’clear span’’ we mean the column inner to inner distance.
- The minimum overlapping length of bars in a beam shall always be provided at least equal to 75 cm or simply 750 mm. The purpose of overlapping is to transfer the loads from one bar to the next.
- As per IS 13920, the minimum diameter of shear reinforcement i.e stirrups shall always be provided as 8 mm.
- When the depth of a beam exceeds 750 mm, then we shall provide side face reinforcement along the two faces of the beam. The total area of this side face reinforcement shall not be less than 0.1% of the web area. It shall be noted that, the side face reinforcement shall be distributed equally on two faces and the spacing of side bars shall not exceed 300 mm or the thickness of web, whichever is less.