Title: Failure Mechanism and Debonding Analysis of Steel and Steel Fiber-Reinforced Concrete Composite Beams

Author(s): Kai Wu, Shiqi Lin, Jianyang Xue, Chao Xu, and Xiaoyi Liu

Publication: Structural Journal

Volume: 118

Issue: 5

Appears on pages(s): 189-204

Keywords: debonding analysis; failure mechanism; four-point bending test; load-deflection curve; steel and steel fiber-reinforced concrete

DOI: 10.14359/51732828

Date: 9/1/2021

Abstract:
With the purpose of solving construction difficulties in composite steel-reinforced concrete (CSRC) structures, the reinforcing bar cage is replaced with steel fiber to form a steel and steel fiber-reinforced concrete (SSFRC) composite structure. By conducting a four-point bending test on 18 specimens, the failure mechanism of SSFRC composite beams without reinforcing bar cages was studied, and load-deflection curves were obtained. The impact of the ratio of steel fiber, the ratio of H-shape steel, and the shear span ratio on failure mode and bonding behavior was analyzed. The bridging effect of the steel fibers can effectively enhance the tensile capacity of concrete after cracking, and debonding failure can be delayed or even avoided. For specimens with a small shear span ratio λ, it can be deemed that the limit of steel fiber ratio ρsf for shearing failure and bending failure was approximately between 1 and 2%. For specimens with a large λ, it was found that the ρsf affected both the debonding failure and the bending failure. The larger the λ, the more steel fibers are needed to transform the failure mode from debonding failure to bending failure. Using the combination of H-shape steel and steel fiber, the damage on SSFRC composite beams can be effectively controlled so that better mechanical behavior can be achieved.