Seismic behaviour of post-tensioned beam-to-column connection using slender energy-dissipating rectangles

An alternative way to decrease the peak response and provide higher robustness against the loss of post-tensioned (PT) force in self-centering structures is to provide them with stiffness degradation and pinching behaviour. In this study, an innovative PT connection using slender steel rectangles as energy-dissipating elements is proposed. Cyclic tests on five specimens considering the effect of thickness, width and number of steel rectangles, and the initial stress of the PT strands were carried out. The results demonstrate that the connections have acceptable seismic response despite stiffness degradation and pinching behaviour of the energy-dissipating steel elements. Specimens with a smaller width of steel rectangles exhibited typical three-plastic-hinge buckling. Smaller thickness of the steel segments would change the buckling behaviour to a multi-wave out-of-plane mode, which is difficult to predict and design for. The energy-dissipating capacity can be increased by increasing the number of steel rectangles while the re-centering capacity remains unaffected. In addition, a verified phenomenological hysteretic model for slender steel rectangles was developed and implemented into OpenSees as a material, which may facilitate further numerical investigations.