Compressive Stress-Strain Relationship of High Strength Steel Fiber Reinforced Concrete

Many stress-strain models of high strength steel fiber reinforced concrete (SFRC) were proposed to account for major characteristics of SFRC; however, the presence of bond strength between steel fibers and matrix was not considered in most studies. In this study, the bond strength is considered in the proposed stress-strain model. The empirical expressions for determining the proposed stress-strain model are obtained by regressing 61 of stress-strain curves of SFRC. The compression tests on SFRC specimens are also conducted to verify the proposed stress-strain model. In addition, the comparison study between pullout energy obtained from fiber pullout tests and that obtained by using empirical equation are presented, since the bond strength is an important parameter to describe fiber characteristics. By treating steel fibers as confinements, the mechanical properties of SFRC are expressed in terms of reinforcing index, equivalent bond strength, and ultimate compressive stress. The proposed stress-strain model has good agreements with the experimental stress-strain curves obtained either in this study or by other researchers. Furthermore, by considering the bond strength between fibers and matrix and treating steel fibers as confinements, the post-peak behavior of SFRC can be well described and avoid either overestimating or underestimating the post-peak behavior.