RETRACTED ARTICLE: Identification of plastic hinge length for pre-tensioning confined HSC columns

Abstract

The effects of pre-tensioned steel straps confinement in improving the plastic hinge length of High-Strength Concrete (HSC) columns was investigated in this study. In the design of confining works for a concrete members, the most difficult part is to determine the column’s region that needed to be confined. To ensure the confinement length that covered the column’s critical length is sufficient, the plastic hinge length is required to be identified beforehand, as confinement is only needed to cover the plastic hinge zone. This also can minimize the confining works as the region outside plastic hinge zone is not required. Six HSC columns were tested to monitor the variation in plastic hinge length due to pre-tensioned pressure. The plastic hinge length is determined based on the observation of strain developments of longitudinal steel bars. Detailed analysis proved that the steel straps confinement enhances the plastic hinge length when the confinement ratio is low. However, it was found that the positive effect reduces with the increase of the confinement ratio. Extensive comparison with the past studies revealed that the existing models were insufficient to predict the plastic hinge behaviour of HSC columns with pre-tensioning confinement. A new equation was proposed and it is sufficient be used as a guideline for the design of confining works using pre-tensioned steel straps confinement method.