Moment-rotation model of self-centering(SC) column base with web-friction-device(WFD) and stiffener-steel(SS) angles

A moment-rotation (M-θ) model is developed to analysis the hysteresis characteristic of the novel self-centering (SC) column base with web-friction-device (WFD) and stiffener-steel (SS) angles, which further promote the transformation from traditional moment resisting structures to resilient structures. Based on the quasi-static cyclic experiment results of twenty specimens, in-depth researches are conducted on the hysteresis behavior of the SC column base, as well as the causes and characteristics of the prestress loss of post-tensioned (PT) strands. A bilinear moment-rotation (M-θs) model, which considering the rotational stiffness contribution of the foundation in compression area, the steel connector end plate in tension area, and the split bolts in tension area, is proposed for the endplate-bolt interface. A trilinear moment-rotation (M-θr) model, which considering the phased mechanical behavior of the PT strands with prestress loss, the WFD, the SS angles and the vertical axial pressure, is proposed for the rocking interface. Thereafter, based on the point of “moment control of single interface, rotation superposition of two interfaces”, the theoretical M-θ model for the novel SC column base is proposed, which exhibits a four-linear characteristic by four key points. The calculation results of the established M-θ model presents satisfactory agreement with the skeleton curve of the cyclic tests, which indicates that the proposed analysis and calculation theory can predict the bending moment capacity of the novel SC column base reasonably.