| The compressive strength of plain concrete subjected to triaxial stress will increase significantly as a function of the increase of confining stress.; Reinforced concrete structural members such as: columns with transverse reinforcement, pile foundation surrounded by soil can be considered to be in this stress state category. Since both of the structural members mentioned above are most essential, a study of the strength of concrete subjected to triaxial stress is important. Many experiments have been done by researchers on this subject, but little direct information is available on the applicability of Mohr's failure envelope.; This study explores quantitatively the applicability of Mohr's failure envelope to the failure analysis of concrete subjected to triaxial compressive stress, as well as the relationships between maximum principal stress, sigma 1, and the compressive strength of concrete, fc ', for both ordinary strength and high strength concrete. In the case the intermediate lateral stress (sigma2) is the same as minimum lateral stress (sigma3). More than 300 experiments regarding ordinary and high strength concrete obtained from the literature has been used in this study.; The non-linear Mohr's failure envelope in terms of the exponent n is proposed and the n values had been determined using existing tests with various values of the ratio ft '/fc'. If, in the future, more ft' data from tests become available, then more precise n values may be determined. An empirical relationship between maximum principal stress, sigma 1, and concrete compressive strength, fc ', is also proposed. |
