Performance of high strength steel bar splice with novel grouted deformed sleeve under tensile load

Abstract

High-strength steel (HSS) bars can solve bar congestion problem in beam-column joints of monolithic precast concrete frame structure. Unfortunately, its application in precast concrete structures is greatly hindered by few researches on HSS bar grout splice. In this paper, utilizing large-diameter HRB600 reinforcements with specified yield strength of 600 MPa, 34 splice specimens were prepared considering the parameters of embedded length, grout strength and inner cavity structure of sleeve. Through uniaxial tension test, it is shown that the embedment length has the greatest effect on the structural performance of grouted splice. For the d28 bar grout splice, 8db is the minimum embedded length to ensure bar fracture failure, which is longer than the normal-strength steel bar grout splice. For the splices with embedded length not smaller than 5db and concentric ribs not less than five, excessive ribs set on the sleeve cannot significantly increase the tensile strength of the grouted splice, but further adding one rib still can effectively reduce the elastic residual deformation. Similar test results have been observed for the effect of grout strength. As the compressive strength increases from 95.3 MPa to 118.2 MPa, the tensile strength improves only by about 2.52%, but the residual deformation decreases significantly by 11.68% on average. For a high-strength large-diameter bar grout splice, it is recommended to set six concentric ribs at each side of the sleeve, and select 8db as the minimum embedded length to achieve reliable performance.