A novel formula for plastic hinge length of reinforced concrete columns in seismic regions

The plastic hinge region length is the critical parameter to determine the deformation capacity of a reinforced concrete (RC) column. The foregoing researches showed that many factores should be included to accurately access the length of plastic hinge, which could be found in the existing formulas. However, the effect of the tension shift of longitudinal rebar was not paid enough attention in these publications. In order to consider the tension shift effect, a novel model of the plastic hinge length was established based upon the equivalent principle of plastic rotation. The quasi-static tests of seven RC columns were carried out to quantify the undetermined parameters in the proposed formula. To eveluate the rationallity of the suggested model, several existing formulas were applied to calculate the plastic hinge length of the tested columns. The comparison between test and calculation shows that the proposed model can predict more accurately the hinge length of 30 columns in the literature with less discreteness than the existing formulas.