International Journal of Engineering and Technology

American Concrete Institute has special provisions for determining the capacity of column when its concrete strength is greater than 1.4 times that of the floor system. Many researchers have observed that these code provisions are overly conservative for edge and corner columns, and overestimate the capacity of interior columns; and proposed new equations which are mostly empirical. In this study, equations derived from theory of elasticity are proposed for determining the effective concrete strength for sandwich, corner, edge and interior columns. Effective concrete strength values, determined using the proposed equations and the equations suggested by other researchers, are compared with the effective concrete strength values deduced from the test data. It is found that the proposed equations predict effective concrete strength values close to test data compared to the values obtained from American Concrete Institute’s Code and also compare well with the results obtained from the equations proposed by other researchers.