Abstract
Small amount of tensile reinforcement causes brittle failure in reinforced concrete beams. Bending test of beams with low reinforced ratio were carried out and design method to prevent the brittle failure is discussed. Cracking strength of beams can be estimated by Sioya's cracking criteria. Ultimate strength should be determined with considering of strain hardening of steel bar. i) As a minimum requirement ultimate strength shall not be less than the cracking strength. ii) In case of the most conservative design, yield strength should be larger than the cracking strength. iii) In the range between i) and ii), suitable judgement should be conducted in taking account of the importance of structural members.
