Analytical Evaluation of Bridge Columns with Double Interlocking Spirals

Abstract

This paper describes a study to determine the effects of shear level, spiral distance, and crossties on the seismic behavior of double interlocking spirals columns. The experimental studies consisted of shaketable testing of six large-scale column models until failure. The effect of different parameters was evaluated based on damage progression and the measured data. The analytical studies included the evaluation of plastic hinge length, lateral force and displacement relationships, shear capacity, development of a nonlinear shear stiffness model, and design recommendations for supplementary crossties. The proposed analytical method to determine the postyielding shear stiffness showed close agreement with the experimental results. The test results indicated that an upper limit on the distance of spiral sets of 1.5 times the spiral radius is appropriate, but supplementary crossties are needed when the shear level is moderate or high.