Title:
Local Bond-Slip Behavior of Reinforcing Bars in High- Performance Steel Fiber-Reinforced Concrete Beams
Author(s):
Rita-Elizabeth Saikali, S. J. Pantazopoulou, and D. Palermo
Publication:
Structural Journal
Volume:
119
Issue:
2
Appears on pages(s):
139-153
Keywords:
anchorage; bond-slip law; development; high-performance steel fiber-reinforced concrete (HPFRC); pullout; strain-hardening concrete
DOI:
10.14359/51734334
Date:
3/1/2022
Abstract:
This paper presents the results of a comprehensive experimental study on the impact of the tensile properties of high-performance steel fiber-reinforced concrete (HPFRC) on the characteristic local bond-slip relationship of steel reinforcement. Due to the tensile toughness of the material, hoop stresses develop in the cover when the bar ribs displace relative to the surrounding concrete. This hoop action enhances the overall bond-slip performance. To quantify this effect, 13 beam specimens comprising HPFRC and containing a short embedment length of a 16 mm (0.63 in.) diameter, deformed reinforcing bar were investigated to quantify experimentally the average local bond strength and bond stress distribution over the anchorage. Two study variables were considered: a) the concrete cover (1Db and 2Db) as the exclusive confining factor; and b) the tensile strength and toughness of the mixtures used as the concrete
matrix. The average bond strength was found to be proportional to the equivalent flexural tensile strength of concrete, reaching a peak value up to 20 MPa (3 ksi) and a substantial bar-slip of 19 mm (0.75 in.) at the end of testing. The smaller concrete cover provided sufficient confinement to develop bar yielding over an anchorage length of 5Db without additional transverse reinforcement.
Increasing the cover resulted in a tougher pullout-splitting
failure mode with reduced deterioration over the cover.