Mechanics of external RC beam-column joints with rectangular spiral shear reinforcement: experimental verification

The innovative technology of continuous rectangular spiral reinforcement applied as shear reinforcement in reinforced concrete beam-column joints instead of the commonly used stirrups is investigated. Inner mechanics issues of external joints for the identification of the failure mechanisms are studied and an experimental project conducted for the purposes of this study is reported. The experimental program comprises four exterior beam-column joints sorted into two groups of two specimens. The length of the column part of all specimens is equal to 1.80 m whereas the column cross section of group A joints is 20/20 cm and the column cross section of group B joints is 30/20 cm. The first specimen of each group has common stirrups whereas the second has continuous rectangular spiral reinforcement. All specimens have been suffered the same full cyclic loading with increasing deformation and two full cycles at every step. From the results it can be obtained that the specimens with rectangular spiral reinforcement have shown a better response in terms of the developing failure mechanisms, maximum loads and hysteretic energy absorption compared to the ones of the specimens with the stirrups.