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 expres-sions 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 addi-tion, 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 experi-mental 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.
This paper reports on the characteristics of drying shrinkage and creep of steel chip reinforced cementitious composite (SCRCC). In this study, first, four restrained wall specimens made of normal mortar and SCRCC with various numbers of steel reinforcing bars (4 or 10) were prepared to compare drying shrinkage characteristics. The specimens were re-strained on the rigid laboratory floor so that shrinkage cracks were induced. The drying shrinkage strains were measured by the contact gauge method and compared with unrestrained small specimens. The number of cracks was simultane-ously observed. Second, bond tests were prepared to evaluate the bond characteristics between the SCRCC and the steel bar. Third, creep tests were performed to improve the accuracy of the analysis of the drying shrinkage behavior. Twelve block specimens were made and a constant flexural load was applied for 7, 14, and 28 days. The observed shrinkage strains and creep strains of SCRCC were modeled according to CEB-FIP Model Code 1990. These models were incor-porated with bond computation between the SCRCC and the steel bar to predict the number of drying shrinkage cracks. The computed equivalent number of cracks based on the shrinkage strain model, the creep model, and the bond model derived from a pull-out test generally agreed with the test results.
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