Comparative Study on Materials used in Various Codes for Design of RC and Steel Structures

Abstract

Indian standard code of practice for plain and reinforced concrete IS 456 was last revised in 2000 after 22 years of the third revision. The major revision done in the new code is shift in design philosophy from working stress method to limit state method. The new code has not shown any significant changes in the concepts of structural design, material properties for high strength of concrete and steel, material grade limitation for seismic design, design of deep beam and walls, design of in-filled frames, design of beam column joint and provisions for effective length of frame members. The code does not clearly mention about mode of failures such as shear, flexure in structural members. In the present paper a comprehensive literature review on the design strength of materials, stress stain curve for concrete, steel and confined concrete, partial safety factors and limitations / recommendations for usage of concrete grade and reinforcement steel grade in design provisions of Indian Standards, American Standards, European Standards, New Zealand Standards, Japanese Standards and from the latest available literature is done. Indian standard code of practice for plain and reinforced concrete IS 456 was initially published in 1953 and subsequently it has been revised in 1957, 1964, 1978 and the latest revision was done in 2000(IS 456: 1953, 1957, 1964, 1978, 2000). Also the latest revision of IS 1893 came up after 18 years and it has many changes as compared to the earlier versions. In the latest revision of IS 1893, it is mentioned that the necessary adjunct for plain and reinforced concrete is IS 456 (IS 1893: 2002). It recommends the use of IS 4326 for earthquake resistant design and construction of buildings (IS 4326: 1993). Further, for the ductile detailing of reinforced concrete structures subjected to seismic forces, reference is given to IS 13920 (IS 13920: 1993). However, there is no discussion regarding the limitations/recommendations for the usage of concrete and steel grades for earthquake resistant Reinforced Concrete (RC) constructions. Influence of high grade concrete on material properties and stress block parameters is not mentioned in IS codes. Change in material properties with time for estimating the existing strength, effect of curing temperature on strength of concrete and tensile strength of concrete are some major points need be incorporated in design codes. The provisions of the above parameters in design codes such as American, European, New Zealand, Japanese and Indian Standards are studied in the present paper and also the importance of these parameters is discussed in detail.