Cyclic Bond-Slip Behavior of Partially Debonded Tendons for Sustainable Design of Non-Emulative Precast Segmental Bridge Columns

Abstract

The precast segmental bridge columns incorporating resettable sliding joints have been proposed to extend the accelerated bridge construction techniques to regions of moderate to high seismicity while fulfilling the sustainability-based resilient seismic design concept. Following a rethink of the design strategy in the light of inspirations from hybrid sliding-rocking joints, the design of resettable sliding joints can accommodate a certain amount of horizontal sliding displacement and adopt partially debonded tendons in a vertical manner, probably resulting in complicated tensile-flexural loading scenarios in these tendons during earthquakes, which is rarely considered in practice. In this paper, the sustainable design of resettable sliding joints is introduced. A tailor-made setup was established and simplified cyclic bond-slip tests were conducted to validate the practicality of the proposed partially debonded tendon system. Twelve specimens were fabricated using different strands and grouting techniques, and a two-stage numerical model was proposed to interpret the experimental results of seven typical specimens. The results suggest that the deterioration of reloading stiffnesses can be captured by an additional effective length caused by bond failure, and the strands perform mostly elastically under relatively large transverse displacements. The loading stiffness of the anchorage is 26.3 kN/mm, and it has significant effects and the proposed two-stage model can satisfactorily capture the envelope of the response of the partially debonded tendons, providing practical design for the proposed partially debonded tendons used in sustainable non-emulative precast segmental bridge columns.