Experimental Performance Assessment of Nearly Full-Scale Reinforced Concrete Columns With Partially Debonded Longitudinal Reinforce-Ment


Abstract eng:
This paper discusses the findings of an experimental study investigating the response of nearly full-scale (~1:1.14) reinforced concrete (RC) columns incorporating partially debonded longitudinal reinforcement in the location of the plastic hinge as a means of improving the ductility capacity of RC columns and RC moment resisting frames. Early fracture of longitudinal reinforcement due to strain concentrations in locations of high moment demands and early concrete crushing due to bond stress effects cause rapid strength and stiffness degradation limiting the ductility capacity of RC columns in buildings and bridges. In this study, the concept of partial debonding of the longitudinal reinforcement at the column ends (i.e., locations of high moment demands) as a means of spreading locally induced deformations over larger rebar lengths is investigated. Spreading local deformations over larger rebar lengths results in smaller peak rebar strains delaying rebar fracture. The efficiency of the proposed concept is quantified through quasi-static cyclic testing of three nearly full-scale cantilever columns. All columns have a 14” × 14” [356 mm × 356 mm] square cross-section and shear span-to-depth ratio of 5.5. The first column has fully bonded reinforcement and serves as the reference column, while the second and the third columns have partially debonded reinforcement at their bottom end over half of the plastic hinge length and the entire plastic hinge length, respectively. The reference column was part of a four-bay three-story RC building designed as special moment resisting frame, per ACI 318-14. All specimens were subjected to a constant vertical load that provided an axial force ratio of 20%, and lateral displacement-controlled cyclic loading of progressively increasing amplitude until complete loss of the vertical load carrying capacity. Based on the experimental data, partial debonding was proven to be effective in decreasing the extent of concrete damage to half of the plastic hinge length, as opposed to the full plastic hinge length for bonded reinforcement. Debonding alleviated strain localizations in the steel reinforcement, at least, for drift ratios below 2%. The peak lateral strength and stiffness decreased with the debonded length. To facilitate further investigation of the proposed concept, three-dimensional finite element models of the column with the fully bonded reinforcement was generated using the ABAQUS general purpose finite element software. The computed response was in good agreement with the test data, providing the means of further assessing the efficiency of the proposed concept in moment resisting frames and other structures.

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Conference Title:
Conference Title:
16th World Conference on Earthquake Engineering
Conference Venue:
Santiago (CL)
Conference Dates:
2017-01-09 / 2017-01-13
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Text je chráněný podle autorského zákona č. 121/2000 Sb.



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 Record created 2017-01-18, last modified 2017-01-18


Original version of the author's contribution as presented on USB, paper 3009.:
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