THE FAMILIAR SYMBOLS OF THE OLD VERSION HAVE BEEN RETAINED, FOR THE CONVENIENCE OF THE USERS OF THE CODE TO A LARGE EXTENT .

The format and arrangement of clauses in the code have been changed from the earlier version and the matter has now been divided into six sections (1) General (2) Materials, Workmanship, Inspection and testing (3) General Design Requirements (4) Special Design Requirements for structural Members and systems (5) Structural Design (limit state method) (6) Structural Design (Working stress method) .This revision incorporates a number of changes , described as (1) While the designers are already aware of the need for basing designs on Requirements of adequate strength and satisfactory serviceability, the concept of limit state which provides a rational approach , taking into account variations in material strength and loads on semi probabilistic basis now has been introduced . This in fact is a rationalisation of the ultimate load method which has been briefly covered in appendix B of IS:456-1964 .The working stress method as practiced earlier has been retained with the design for shear and torsion being aligned with the corresponding provisions for limit state method of Design.(2) The clauses dealing with the sampling and acceptance criteria for concrete have been revised by elaborating the concepts of the stastical Quality control and introducing characteristics strength of concrete ,to bring inline with the latest trends in Quality control of concrete.(3) Method of Design for shear and torsion has been.completly revised , incorporating the results of the latest research on the captioned subject matter deliberation required to be maintained by the Sectional Committee .(4) The concept of the development length for reinforcement has been introduced. The requirements regarding checking of the bond stress has now been replaced by an extension of the concept of the department length. SI units have now been used in the code , while deciding on the symbols used in the code the recommendations of the ISO 3898-1976 Bases for design of Structures--Notations -- General symbols have been taken into consideration . However, considering the convenience of the users of the code , the familiar symbols of the old version have been retained to the large extent.