Manjunath S.Amalkar1, Renukadevi M.V.2, Jagadish K.S.3, and Somanath M. Basutkar4
1) Lecturer and Assessment Head, CAE Section,
Higher College of Technology, Muscat.
Email: manjuamalkar@yahoo.com
2) Professor & HOD, Department of Civil Engineering,
R.V. College of Engineering, Bengaluru
Email: renu_gowri@yahoo.co.in
3) Former Professor, Department of Civil Engineering,
Indian Institute of Science, Bengaluru
Email: ksjagadish@gmail.com
4) Assistant. Professor, Department of Civil Engineering,
R.V. College of Engineering, Bengaluru
Email: somanath_basu@yahoo.co.in
Keywords: Hollow concrete block, masonry efficiency, correction factor, strength-based design.
Abstract. There are a number of factors which govern the strength of masonry namely strength and elasticity of masonry units and mortar, slenderness ratio of the wall, nature and magnitude of eccentric loads, masonry efficiency (ratio of masonry strength to unit strength) etc. There have been a number of publications on the factors mentioned above although many are with respect to brick masonry or masonry used in western countries. The correction factors for prisms indicated by the Indian code sometimes leads to prism strength which is more than block strength. An attempt is made in this paper to revisit the correction factors indicated by the Bureau of Indian Standards.
This paper investigates the compressive strength of hollow concrete block masonry. Stack bonded prisms with various height to thickness ratios are tested. Cellular concrete blocks and hollow concrete blocks were investigated for their respective compressive strengths, the stress-strain relationship and masonry efficiencies (ratio of prism strength to unit block strength). In addition to this, the effect of face shell bedding has also been investigated and reported.
Correction factors recommended by the I.S.Code are examined and shown how the codal provisions lead to unrealistic prism strengths. It is also suggested to use height to width ratio of 5 used in brick masonry for normalization of prism strengths. Finally, it is also suggested to use the coefficient of variation to arrive at the strength-based design of masonry.