Examination of cover spalling in high strength columns

ACI 318–02 provisions for stress block parameters were derived using normal-strength concrete column tests. Due to the early cover spalling in high-strength concrete, however, the use of current ACI stress block parameters results in estimations that are not conservative for high-strength concrete column sections. In this paper the effect of premature cover spalling in high strength concrete columns (55 MPa < https://www.w3.org/1998/Math/MathML" display="inline"> f c ' < 140 MPa) is examined numerically. The proposed method for nominal moment capacity calculation employs rectangular stress block parameters of ACI 318–02 provisions and analytically derived strength reduction parameters to integrate the effect of early cover spalling into the design process. Although the proposed method for moment capacity calculation is analytically derived, its results are validated with the experimental data from 224 column tests reported in the literature.