Thursday, February 09, 2017

What does IS:456 covers?

IS:456-2000-Plain and Reinforced Concrete for Building Construction:

This is the fourth revision of the standard. The common methods of design and construction of plain or reinforced concrete structures is covered in this code. The code is divided into 5 sections, which detail out various guidelines and specifications.

Section 1: 

                        defines the scope, terminology and symbols.


Section 2:

                        explains about materials, workmanship, inspection and testing. It includes types of cement, use of blended cements with mineral admixtures like flyash and ground blast- furnance slag, quality norms on water, admixtures, well defined exposure conditions, grade of concrete, formula for estimation of modulus of elasticity of concrete, durability of concrete, construction  joint etc.

Section 3:

                    tells about general design consideration. It covers methods of design, various loads and load combinations, stability of structure against overturning and sliding, fire resistance requirements, Linear Elastic Theory to calculate internal action produced by design loads, recommendation regarding effective length of cantilever, recommendation for deflection due to lateral loads. According to clause no. 18.2, there are two methods of design (a) Working stress method & (b) Limit state method. Clause 26 gives guidelines for " Requirements governing reinforcement and detailing" wherein maximum and minimum spacing between reinforcement and cover requirements for various exposure conditions is specified.


Section 4:

                         (Clause 28 to 34) relates o " Special Design Requirements for Structural Member & Systems". Guidelines for Deep Beams, Flat Slabs, Walls, Stairs, Stairs, and footings etc are covered under this section.


Section 5:

                               (Clause 35 to 43) covers " Strutural Design ( Limit State Method)" in detail. Various limit states including that of flexure, compression, shear, Torsion, Deflection, Cracking etc are discussed.


Annex B, discusses the requirements of " Working Stress Method".


Annex D, gives moment coefficients for rectangular slab panels.