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

Abstract

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.

Shear Strength Prediction Equations and Experimental Study of High Strength Steel Fiber-Reinforced Concrete Beams with Different Shear Span-to-Depth Ratios

“…Swamy et al [27] set the bond strength between steel fibers and concrete matrix at 4.15 MPa. Liao et al [2] and Perceka et al [9] conducted single-fiber pullout tests to determine the equivalent bond strength that describes the bond strength of the fiber-matrix interface. In order to account for the equivalent bond strength, τ eq , Equation (1) that was proposed by Kim et al [2] can be used.…”

“…Using high-strength concrete (HSC) with compressive strength exceeding 70 MPa and high-strength steel (HSS) with yield stress of 685 MPa or greater can reduce the member section size and the volume of concrete and steel bars for the entire building structure [1]. The durability of concrete can be improved, owing to lower water-to-cementitious materials ratio of the HSC as well [2]. However, concrete becomes more brittle as its compressive strength increases and greater transverse reinforcement is required accordingly [2][3][4][5].…”

“…The durability of concrete can be improved, owing to lower water-to-cementitious materials ratio of the HSC as well [2]. However, concrete becomes more brittle as its compressive strength increases and greater transverse reinforcement is required accordingly [2][3][4][5]. Short and discontinuous steel fiber can be used as an alternative material to improve the ductile behavior of concrete [2,[6][7][8][9].…”

“…However, concrete becomes more brittle as its compressive strength increases and greater transverse reinforcement is required accordingly [2][3][4][5]. Short and discontinuous steel fiber can be used as an alternative material to improve the ductile behavior of concrete [2,[6][7][8][9]. Previous research studies have shown that adding steel fibers to concrete beams could enhance shear resistance, toughness, promote flexural failure and ductility, and potentially act as a substitute for conventional shear reinforcement [10][11][12][13][14][15][16][17].…”

“…Previous research studies have shown that adding steel fibers to concrete beams could enhance shear resistance, toughness, promote flexural failure and ductility, and potentially act as a substitute for conventional shear reinforcement [10][11][12][13][14][15][16][17]. In addition, the randomly oriented steel fibers provide bridging action across the microcracks in the matrix and improve resistance to crack opening [2,9,[18][19][20]. The shear stress on the interface between the steel fibers and the surrounding matrix (bond strength between steel fibers and matrix) is a key parameter in the bridging role and in providing more tensile strength during fracturing.…”