Study on stress strain characteristics of high strength concrete

摘要

The High Strength Concrete (HSC) is generally defined as concrete above M55. Bureau of Indian Standard (BIS) code IS 456:2000 in clause 6.1 (Table-2) has identified concrete grade M10 to M80. However, note: 2 under Table 2 of IS 456:2000 states that for concrete of grades higher than M55, design parameters given in the code of practice may not be applicable and values may be obtained from specialized literatures and experimental results. In the absence of design parameters in the codes, designers are not able to use high strength concrete, even though the laboratories and RMC plants in the country have the expertise to design and produce high strength concrete. Therefore, this research was intended to develop design parameters for high strength concrete so that designers can use high strength concrete in design of structures with confidence. Whilst there are many publications proposing the stress block models for HSC beams, a universally accepted stress block model is yet to be developed. In most design standards, the conventional rectangular stress block developed for Normal Strength Concrete is still being used for design of HSC beams. The aim of this study was to develop design parameters for flexural design of High Strength Concrete for incorporation in Indian Standard for Design (IS 456:2000). This paper presents the comparison of empirical formulae proposed for calculation of ultimate strain and strain at peak stress for High Strength Concrete in European design standard EC: 02-2004 with the experimental results. The factors for effective strength and effective height of compression zone in stress block for High Strength Concrete worked out from experimental results are also compared with EC: 02-2004 empirical formulae.