Detail guidelines on Structural Design Codes And Standards
Design of RCC Structural Components: In this civil engineering article, you will be familiar with the minimum standards necessary for the design of RCC structural elements of a structure like columns, beams, slab and foundation.
Besides, the information is also given on the minimum safe standards for the reinforcing bars which should be applied for the design of the above mentioned structural elements.
Minimum cross-sectional dimension for a Column: Minimum standard size should be 9″x 12″(225 MM x 300 MM). It is recommended to use M20 grade concrete for construction as per IS 456:2000. The minimum steel in a 9″ x 9″ column should contain 4 bars of 12 MM containing stirrups of 8 MM steel rings at a spacing of 150 MM centre to centre. In a 9″ x 12″ column, two more bars can be added to make the total to 6 bars of 12 MM diameter. This design will be secured for up to G+1 floors.
Minimum RCC beam size : It should not be under 9″x 9″(225MM X 225MM), containing a extra slab thickness of 125 MM.
A minimum of 4 bars can be used containing 2 bars of 12 MM thickness in the bottom of the beam, and 2 bars of 10 MM at the top of the beam. The required concrete cover should be 40 MM. It is recommended to utilize M20 grade of concrete (1 part cement : 1.5 parts sand : 3 parts aggregate : 0.5 parts water).
Minimum thickness of RCC slab : It should be minimum 5″ (125MM) as a slab may comprise of electrical pipes implanted into them with thickness 0.5″ or more for internal wiring, which in fact minimizes the depth of slab at specific areas. It leads to cracking, decay and water leakage during rains. So, there should be a minimum thickness of 5″.
Minimum size of foundation : A size of 1m x 1m should be ideal for a single storey of G+1 building, where the safe bearing strength of soil should be 30 tonnes per square meter, and the impending load on the column does not be in excess of 30 tonnes,. Minimum depth of footing should remain 4′ underneath ground level. It is recommended to retain deepness up to had strata.
Reinforcing bar details (minimum):
1. Columns: 4 bars of 12mm steel rods FE 500.
2. Beams: 2 bars of 12 mm in the bottom and 2 bars of 10 mm on the top.
a) One Way Slab: Main Steel 8 MM bars @ 6″ C/C and Distribution Steel of 6 mm bars @ 6″ C/C
b) Two Way Slab: Main Steel 8 MM bars @ 5″ C/C and Distribution Steel of 8 mm bars @ 7″ C/C
4. Foundation: Initially, 6″ of PCC layer should be provided. Over it, there should be a tapered or rectangular footing with minimum 12″ thickness. Steel mesh of 8 mm bars @ 6″ C/C should be placed. In a 1m X 1m footing, it should comprise of 6 bars of 8 mm on both portions of the steel mesh.