Experimental study on the plastic rotation capacity of reinforced high strength concrete beams

This paper describes an experimental study on the plastic rotation capacity of reinforced high strength concrete beams. Thirty-six beams with various compressive strengths of concrete, tensile reinforcement ratios, compressiv e reinforcement ratios, and patterns of loading (1 point loading and 2-poin t loading) were tested to evaluate the plastic rotation capacity, extreme f iber concrete compressive strain and equivalent plastic hinge length, etc. The same quantities were also obtained from numerical analysis and compared with experimental data. According to the results, the yield curvatures obt ained from experiments turned out to be quite close to those obtained from theoretical approach. However, the experimental results for ultimate curvat ures were significantly larger than those of theoretical prediction based o n the assumption of epsilon (cu) = 0.003. Based on these observations, a ne w formula for ultimate strain is proposed for high strength concrete beams. Also the test results for plastic rotation capacity were found to be close r to those obtained using moment-curvature relationship considering tension stiffening of concrete and shear effect than those obtained using equivale nt plastic hinge length. This substantiates that for accurate evaluation of plastic rotation capacity the consideration of tension stiffening of concr ete and shear effect is most important.