ACI says the study investigated the shear strength of normal-strength concrete (NSC) and steel fibre-reinforced high-strength concrete (SFRC) composite beams.
Composite beams of NSC and SFRC are used for strengthening existing buildings and precast concrete constructions.
Twelve simply supported SFRC composite beams were tested to investigate the effect of steel fibres on the shear strength of the composite members. Test variables included area ratio of SFRC to NSC and the use of minimum reinforcement for horizontal shear transfer in concrete interface.
According to ACI, results showed that vertical shear strength of SFRC composite beams with shear reinforcement increased as the area ratio of SFRC increased.
“On the other hand, SFRC composite beams without shear reinforcement were susceptible to horizontal shear cracking at the interface, which indicates that minimum reinforcement for horizontal shear transfer was required for the monolithic behaviour of NSC-SFRC composite beams,” the institute adds.
Design recommendations were then given to reasonably predict the shear strength of SFRC composite beams.
This paper was written by Chul-Goo Kim, Hong-Gun Park, Geon-Ho Hong and Su-Min Kang.