Understanding HYSD reinforcing bars used in Indian construction industry (from seismic point of view)
  Brijesh Singh, V.V. Arora and Lalit Yadav
  Tensile behaviour was investigated for reinforcing steel bars used in the Indian Construction Industry; this was done to ascertain the level of conformity of the tested parameters with the Indian & other International standards. The samples from total of eight (08) companies operating in India were investigated. In the study, results of large number of tests of different brands have been analysed and discussed. The mean, standard deviation and values of test results have been worked out and their distribution pattern was studied. Experimental test results of the ratio of TS/YS indicated that there is need to increase the TS/YS ratio for Fe-500/500D grade steel as majority of steel manufacturers are providing higher ratio of TS/YS than those specified value in IS: 1786. This increase will help in improving ductility of rebars in situations where high inelastic deformations of structural members as demanded by design philosophies are required. From results of study, it can also be inferred that, for steels of same brand with better quality control, the maximum Yield Strength values can easily be restricted to match the requirements of Fe-500S as given in IS:1786 or ACI code. ASTM A706/A706M and AS/NZS 4671 specifies both minimum and maximum Yield Strengths for all the steel grades while no upper capping is given on higher limit of Yield Strength in IS code for all the steel grades except for steel grades with S series, which is must to avoid undesirable brittle shear failure of structures. Also a study was carried out to determine the relationship between carbon % and yield and ultimate tensile strength for three different diameters. It was observed that no clear relationship was observed as results varied with respect to yield and ultimate strength for steel bars commonly used in Indian Construction Industry. ASTM A706/A706M and AS/NZS 4671 specifies both minimum and maximum yield strengths while no upper capping is given on higher limit of yield strength in IS code which is must to avoid undesirable brittle shear failure of structures under earthquake loadings.
 

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