Experimental Analysis and Simulation of Cyclic Behavior for New RC Bridge Columns with High Strength Hook Ended Steel Fibers

The development of high strength concrete and reinforcement has become more mature nowadays. The purpose of New RC project was aimed to reduce the member sections and increase the available space of high rise buildings by using high strength concrete (f’c > 70 MPa) and high strength rebars (fy > 685 MPa). Material consumptions and member sections can be further reduced owing to the upgrade of strength. However, the nature of brittleness of high strength may also cause early cover spalling and other ductility issues. Addition of steel fibers is an alternative as transverse reinforcement. This study aims to investigate the cyclic behavior of New RC bridge columns in addition to high strength hooked steel fibers. Four full scale bridge columns are subjected cyclic lateral loading to verify their responses and deformation capacity. The experimental results show that the application of high strength materials on bridge column is feasible. Quantification of confinement efficiency of the steel fibers is also conducted in this study. By using the equivalent transverse reinforcement concept via TR value, the amount of fibers required to reach the same performance can be further determined. The test results show that by adding 1.5% of high strength hooked steel fibers, great deformation capacity is developed either stirrups spacing is even increased to 2 times of that of control specimen or elimination of all tires in New RC bridge columns.