The use of steel fiber-reinforced concrete (SFRC) has increased due to its advantages, including improving post-peak behavior in compression, preventing catastrophes from excessive shear stress, and reducing shrinkage. However, incorporating fibers into fresh concrete with common mix proportions can cause the “balling effect.” Moreover, the mechanical performance, particularly tensile stress-strain behavior, often falls short; tensile strength decreases once a central crack forms on the specimen surface. With advances in material technology, SFRC continues evolving. Highly flowable strain-hardening fiber-reinforced concrete (HF-SHFRC) is a new generation of SFRC that behaves like self-compacting concrete (SCC) when fresh and exhibits the strain-hardening and multiple cracking properties of high-performance fiber-reinforced cementitious composites (HPFRCC) once hardened. These mechanisms enable smooth force redistribution from concrete to steel fibers. This paper reviews how HF-SHFRC, often called SFRC, can replace transverse reinforcement while still providing lateral strength and ductility. The proposed toughness ratio (TR) equation, used to determine equivalent confinement for SFRC columns with transverse reinforcement, is revisited since it successfully supported a numerical model simulating cyclic column behavior. Additional examples measuring confinement efficiency through a parametric study are provided, where column size and SFRC properties are based on past research. The findings align with prior investigations showing steel fibers enhance strength and ductility while preventing premature failure. This example can guide engineers to better understand fiber effects in columns and how to incorporate them into RC members for structural applications.

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The Use of Highly-Flowable Strain Hardening Fiber Reinforced Concrete (HF-SHFRC) in Replacing Confinement Reinforcing Bars in RC Columns: An Overview and a Parametric Study

  • Wisena Perceka,
  • Wen-Cheng Liao

摘要

The use of steel fiber-reinforced concrete (SFRC) has increased due to its advantages, including improving post-peak behavior in compression, preventing catastrophes from excessive shear stress, and reducing shrinkage. However, incorporating fibers into fresh concrete with common mix proportions can cause the “balling effect.” Moreover, the mechanical performance, particularly tensile stress-strain behavior, often falls short; tensile strength decreases once a central crack forms on the specimen surface. With advances in material technology, SFRC continues evolving. Highly flowable strain-hardening fiber-reinforced concrete (HF-SHFRC) is a new generation of SFRC that behaves like self-compacting concrete (SCC) when fresh and exhibits the strain-hardening and multiple cracking properties of high-performance fiber-reinforced cementitious composites (HPFRCC) once hardened. These mechanisms enable smooth force redistribution from concrete to steel fibers. This paper reviews how HF-SHFRC, often called SFRC, can replace transverse reinforcement while still providing lateral strength and ductility. The proposed toughness ratio (TR) equation, used to determine equivalent confinement for SFRC columns with transverse reinforcement, is revisited since it successfully supported a numerical model simulating cyclic column behavior. Additional examples measuring confinement efficiency through a parametric study are provided, where column size and SFRC properties are based on past research. The findings align with prior investigations showing steel fibers enhance strength and ductility while preventing premature failure. This example can guide engineers to better understand fiber effects in columns and how to incorporate them into RC members for structural applications.