Tests of High‐Strength Concrete Columns with Intervening Floor Slabs

This paper describes the results of tests of 13 reinforced concrete column‐slab specimens, in which the columns are very strong concrete—in the 14‐k/sq in. (96 MPa) compressive strength range—while the intervening floor slabs are much weaker. The slab concretes range from about 3–6 k/sq in. (21 to 42 MPa) compressive strength. In addition to the variation in the slab concrete strength, the slabs represent either interior or edge conditions, and two different slab thicknesses are included. The interest in this series of tests is axial load transmission through the weaker slab concrete, and no moments are imposed on the slab‐column connection. The data are analyzed with two objectives. One is to investigate the general adequacy of section 10.13 of the 1989 ACI code (ACI 318‐89). The provisions do not appear to be conservative when the column concrete is extremely strong. The second goal of the research is to develop a better understanding of the problem, and to develop a better prediction method or procedure.