Title: Bond Behavior of Reinforcing Bars in Tensile Strain-Hardening Fiber-Reinforced Cement Composites

Author(s): Shih-Ho Chao, Antoine E. Naaman, and Gustavo J. Parra-Montesinos

Publication: Structural Journal

Volume: 106

Issue: 6

Appears on pages(s): 897-906

Keywords: bond stress; development length; fiber-reinforced cementitious composites; high-performance cement composites; pullout; strain

DOI: 10.14359/51663191

Date: 11/1/2009

Abstract:
Bond between deformed reinforcing bars and concrete induces significant tensile stresses that lead to cracking in concrete due to its weak and brittle nature in tension. Contrary to plain concrete and conventional fiber-reinforced concrete, high-performance fiber-reinforced cement composites (HPFRCCs) show strainhardening response under tension and, thus, their use can lead to enhanced bond performance. Pullout-type tests comprising various types of loadings were carried out to investigate the influence of strain-softening and strain-hardening fiber-reinforced cementitious (FRC) composites on the bond strength and the bond stress-slip response of deformed reinforcing bars. Test results showed that the bridging effect provided by fibers in FRC composites after cracking can effectively provide post-cracking tensile capacity to the concrete matrix and limit crack width, thereby leading to enhanced bond resistance. HPFRCC specimens gave the best bond performance in terms of bond strength and stiffness retention capacity, as well as damage-control ability.