Cyclic behavior of bridge columns with partially unbonded seven-wire steel strands to increase post-yield stiffness
Journal
Engineering Structures
Journal Volume
258
Date Issued
2022
Author(s)
Abstract
A new method of increasing post-yield stiffness of bridge columns to reduce the residual displacement after large earthquakes is proposed. In the proposed method, partially unbonded unstressed seven-wire steel strands are used as elastic element to increase the post-yield stiffness of the column. Three large-scale column specimens were tested using lateral cyclic loading to investigate the seismic performance of the proposed column. Test results showed that the use of the unstressed partially unbonded steel strands effectively increased the post-yield stiffness ratio of a conventional bridge column from −0.3% to 6.4%, which exceeded the 5% post-yield stiffness ratio that has been shown in the literature to reduce the residual displacement significantly. Test results also showed that the post-yield stiffness could not be maintained when the strands started to bulge in compression. The ultimate drift was slightly reduced from 5.76% to 4.77%. The use of fully bonded strands further increased the post-yield stiffness ratio to 8.8%. However, the ultimate drift ratio was greatly reduced to 2.84%. To predict the behavior of the proposed column under lateral load, a pushover model was developed. The strain of the partially unbonded strand was calculated based on deformation compatibly with the longitudinal deformed steel bar. The effect of anchorage slip was considered. Comparison with the test results showed that the proposed model captured well the envelope response of the proposed column. © 2022 Elsevier Ltd
Subjects
Near-fault ground motions; Post-yield stiffness; Residual displacement; Seismic; Self-centering
SDGs
Other Subjects
Stiffness; Bridge columns; Cyclic behavior; Large earthquakes; Near fault ground motion; Post-yield stiffness; Residual displacement; Self centering; Steel strand; Stiffness ratios; Wire steels; Seismology; bridge; column; cyclic loading; displacement; earthquake engineering; ground motion; reinforcement; seismic design; stiffness
Type
journal article