150MPa 초고강도 콘크리트와 철근의 부착응력 평가

Abstract

The purpose of this paper is to evaluate the bond characteristics of 150㎫ ultra high-strength concrete and reinforcing steel. In this study 9 specimens for the pull-out test and 9 specimens for the bending test are performed to evaluate the mechanical bond characteristics according to changes of the tensile stress and the concrete strength but there are many variables to decide the basic structural behavior of ultra high-strength concrete. The major variables are slip of the bar and load- deflection, compressive strength effected on lap splice, the change of the bar lap splice, the change of bar spacing, the shearing bar existence and nonexistence. The results confirmed that the bond stress has decreased when the bar diameter has increased and bond stress has increased when the covering depth increased. Also it show the ductile behavior when the bar diameter increased and the sharply sliding phenomenon after the sliding appeared 0.06㎜ in the early age cracking. Besides the early age cracking happened lap splice length. The experimental results show lower 1.07-3.9 times than Orangun, Jirsa, Breen and Zuo, Darwin equations.