Seismic Design of New Rc Beams II – Anti-Buckle Spacing for High Strength Beam Bars

This sub-project is proposed in term of three years. The main goal of the first year (approved) is toinvestigate the design method for the plastic hinge relocation of New RC beams. The second year topic(applying) will focus on the buckling behavior of the high strength SD685 reinforcing steel bars. Then thethird year topic will discuss the problem of fatigue design subjected to elastic vibration for the New RC beamsor slabs.In the project applying, the anti-buckle spacing is restricted to 6db according to the seismic design chapterof ACI 318-14. However, the strength of deformed reinforcement is limited to 420 MPa. This is the reasonwhy the SD 690/790 deformed bars are keen to find the anti-buckle spacing for the seismic design. Toinvestigate the topic, two experimental ways are proposed. One is to perform a cyclic loading test on 5cantilever New RC beams to know the real behavior of beam bar buckling. The other is to perform what wecalled low-cycle fatigue testing on single deformed steel bar with different bar diameters and unsupportedlengths to investigate the rational s/db recommended for design. The fatigue life cycles under plastic strainranges can also be evaluated by means of the low-cycle fatigue testing