New Testing Approach for Extracting the Shear Friction Material Properties of Ultra-High-Performance Fiber-Reinforced Concrete

Flexural performance of pretensioned ultra-high performance fibre reinforced concrete beams with CFRP tendons

“…where m is the slope of the shear-capacity/normal-stress relationship determined from shear friction tests. From tests conducted by Sturm et al [48] on UHPFRC, this angle was determined to be 14°.…”

“…The length of the cylinder was taken as 200 mm for calculating the size-effect in compression since that was the length considered in Sobuz et al [52]. Shear friction properties used to determine the geometry of the softening wedge were estimated from tests performed by Sturm et al [48]. The stress-strain relationship of the CFRP tendon was obtained from tests performed by Shapack [13].…”

A displacement based approach for the analysis, development, and design of reinforced concrete

“…It used to be difficult and costly to determine these properties, particularly for high strength materials, but new inexpensive procedures have now been developed. [14][15][16][17][18][19][20][21][22] It is worth bearing in mind that the SF properties in Figure 2 can also be derived when the sliding plane in -Figure 1 is initially cracked, as in Walraven et al, 23 and also when the normal stress σ N is tensile such as in the work of Johal et al 24 Both an initial crack and a normal tensile stress reduce the shear resistance. As an example, the initially cracked concrete behavior is shown as the dashed line in Figure 2 where the shear to cause sliding V ui is much smaller than that of the uncracked concrete V u0 and is equal to zero when unconfined.…”

“…The first consideration is to determine the standard strain based material properties such as the concrete compressive and tensile strengths, moduli, creep, and shrinkage. In addition are required the PI material properties: the PI shear friction properties represented by Figure 2 are enhanced by fibers both in their strength and ductility; and the bond‐slip properties represented by Figure 3 19,26 . One further property required for UHPC is the relationship between the crack width w and the axial stress across a crack σ fi in Figure 17.…”

“…The shear capacity V ux in Figure 2 is the shear capacity for a confinement σ Nx at the onset of sliding, and it can be seen that when sliding occurs the shear resistance τ SFx reduces. It used to be difficult and costly to determine these properties, particularly for high strength materials, but new inexpensive procedures have now been developed 14–22 …”