2017 Volume 71 Issue 1 Pages 501-508
Recently, ultra-high strength fiber reinforced concrete（UFC）was developed, however it is hardly applied to deformed steel bar reinforced concrete because of cracking caused by autogenous shrinkage resulting from the hydration of the binder. The maximum size of aggregate for UFC is limited less than 2.5mm. On the other hand, ultra-high performance concrete（UPC）, consisting of modified grading cement, water, fine aggregate and also coarse aggregate, was developed and widely used for architectural design material such as colored precast members. The compressive strength and the tensile strength of UPC are higher than 150N/mm2 and 8N/mm2 respectively, and also the UPC fracture under bending or tensile stress is extremely ductile.
In this study, the mechanical behaviors of reinforced UPC are researched and the stopper consisting of UPC filled steel tube is discussed. According to the test results, even the shear span/height ratio is 0.75, the following conclusions are obtained.
1）Reinforced UPC filled steel tube failed by bending and the hysteretic load-deflection curve satisfied the performance requirements of stopper.
2）The more the ratio of longitudinal reinforcing bars, the larger the maximum deflection and maximum load capacity of UPC filled steel tube stopper.
3）Even when shear span/height ratio is 0.75, fracture pattern of reinforced rectangular cross section UPC beam without steel tube was also bending failure because of high shear strength and extremely ductile behavior of UPC.
