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Title: Seismic Performance of Reinforced Concrete Columns Strengthened with Ultra-High-Performance Fiber Reinforced Concrete and Shape Memory Alloy

Author(s): Ekkawi

Publication: Web Session

Volume:

Issue:

Appears on pages(s):

Keywords:

DOI:

Date: 10/17/2021

Abstract:
Structure failures that occurred over the past years due to earthquakes were triggered by the failure of reinforced concrete (RC) columns. This is because RC columns built according to old code seismic provisions lack adequate ductility and flexural capacity to dissipate seismic energy through their displacement. Correspondingly, the research area explores a new seismic strengthening system applied to bridge columns through utilizing Shape Memory Alloy (SMA) and UHPC. SMAs are a unique class of alloy that can recover large deformations by either unloading or heating. On the other hand, the used UHPC contains steel fibers to increase the material’s tensile strength and Carbon Nanofibers (CNF) to bridge the cracks at the microscale level when subjected to loading. Three large scale RC circular columns are constructed according to old code seismic provisions to introduce a seismic performance deficiency. The first specimen will be kept in its as-built conditions. The second and third specimens will be strengthened in flexure through anchoring SMA strips vertically along the plastic hinge length. The confinement will be achieved by casting UHPC around these two along their plastic hinge lengths; however, the UHPC cast around the third specimen will include SMA fibers. All specimens will be tested under lateral cyclic loading with a defined loading protocol and a constant axial load. The behavior of the columns will be assessed in terms of peak lateral loads, ultimate drift capacity, energy dissipation capacity, displacement ductility, residual displacements, and experienced damage. The most optimum strengthening profile will be applied to the damaged unstrengthened specimen. The findings will prove the efficiency of the strengthening system as an emergency repair for severely damaged columns.