Title: Bond Stress-Slip Response of Reinforcing Bars Embedded in FRC Matrices under Monotonic and Cyclic Loading

Author(s): Siva Hota and Antoine E. Naaman

Publication: Structural Journal

Volume: 94

Issue: 5

Appears on pages(s): 525-537

Keywords: bond (concrete to reinforcement bar); compressive strength; slip; confined concrete;cracking (fracturing); ductility; energy absorption; fiber-reinforced concretes; monotonic loading;reversed cyclic loading; spiral reinforcement;

DOI: 10.14359/502

Date: 9/1/1997

Abstract:
The bond stress versus slip response of reinforcing bars embedded in fiber reinforced cement based composites is investigated. Three types of loading were carried out: 1) monotonic loading, 2) unidirectional cyclic loading, i.e. loading-unloading by equal increments of slip, and 3) fully reversed cyclic loading in a pull-pull mode. Two types of failure were observed: a frictional type of pull-out failure, and a splitting mode type of failure. Typically, for all applied loading, the failure of all bars embedded in SIFCON matrices was by frictional pullout, while failure of all bars embedded in plain concrete was by splitting of the concrete around the embedded bar. When fiber reinforced concrete was used a mixed type of failure occurred depending on the test parameters. The confined plain concrete specimens failed by spalling of the concrete outside the confined region, i.e. the concrete cover. Generally, in the absence of fibers, failure was rather brittle; the addition of steel fibers resulted in a more ductile failure. Reinforcing bars embedded in SIFCON showed much greater bond strength, higher energy absorption, and maintained substantially larger slips at high stresses, than bars embedded in plain concrete, confined concrete, or fiber reinforced concrete.