In the last decade, the U.S. construction industry has faced enormous challenges: aging infrastructure, corrosion of steel reinforcement, and the need for sustainable materials with a longer service life. Glass-Fiber-Reinforced Polymer (GFRP) rebar has emerged as one of the most reliable alternatives to traditional steel.
However, design with GFRP reinforcement in the U.S. must strictly follow ACI 440.11-22 – Building Code Requirements for Structural Concrete Reinforced with GFRP Bars.
This article explains what ACI 440.11-22 means for engineers, contractors, and project owners, and how to correctly design concrete structures with GFRP bars that meet U.S. codes, DOT requirements, and ASTM standards.
Why GFRP Rebar?
Steel reinforcement has been the backbone of concrete for over a century, but it comes with a severe problem: corrosion. Deicing salts, marine environments, and moisture exposure reduce service life dramatically.
By contrast, fiberglass rebar (GFRP) offers:
- 100% corrosion resistance – no rusting, even in chloride-rich environments.
- Alta resistência à tração – 2–3x stronger than steel by weight.
- Light weight – 75% lighter than steel, reducing handling and shipping costs.
- Electromagnetic neutrality – perfect for hospitals, laboratories, and data centers.
- Sustentabilidade – less concrete cover required, lower CO₂ footprint, longer life cycle.
What Is ACI 440.11-22?
ACI 440.11-22 is the official code by the American Concrete Institute that establishes how to design and detail concrete structures reinforced with GFRP bars. It ensures:
- Uniform design methodology across the U.S.
- Safety margins based on material behavior of GFRP.
- Acceptance of GFRP rebar in national and state building codes.
Related Standards and Codes:
- ASTM D7957 – Specification for solid round GFRP bars.
- ICC-ES AC454 – Acceptance criteria for FRP bars in concrete.
- IBC 2024 – Includes references to FRP reinforcement.
- DOT Approved Product Lists (APL) – Required for bridges and infrastructure projects.
Scope of ACI 440.11-22
ACI 440.11-22 allows GFRP rebar in:
- Bridge decks and transportation structures.
- Parking garages with high exposure to deicing salts.
- Marine structures such as seawalls and piers.
- Foundations, slabs, and walls in residential and commercial projects.
Limitations:
- Seismic zones: some restrictions apply in high Seismic Design Categories.
- Fire resistance: GFRP softens under extreme temperatures, requiring special detailing.
- Anchorage & bends: larger radii compared to steel.
Key Design Principles
1. Material Properties
- Tensile strength: typically 600–1200 MPa.
- Modulus of elasticity: ~45–60 GPa (¼ of steel).
- Stress-strain curve: linear elastic until rupture (no yield plateau).
2. Flexural Design
- Flexural strength based on balanced failure conditions.
- Concrete crushing governs design; tension failure of GFRP must be avoided.
3. Shear Design
- Shear reinforcement (stirrups) may be GFRP or steel, depending on project requirements.
- Special detailing rules ensure ductility.
4. Serviceability
- Deflection checks are critical due to lower stiffness.
- Crack width control requires larger bar diameters or closer spacing.
5. Development Length & Splicing
- Lap splice lengths are longer than for steel.
- Sand-coated or helically wrapped surfaces improve bond to concrete.
Construction & Detailing
- Bend radius: typically ≥ 10 × bar diameter.
- Cutting: only with diamond blade saws.
- Placing: plastic chairs or non-corrosive supports recommended.
- Tying: plastic or coated wire ties preferred.
Practical Example
Imagine designing a bridge deck slab:
- Using #3 (3/8 in) GFRP rebar spaced at 6 in centers.
- ACI 440.11 provides equations to check flexure, shear, and serviceability.
- Compared to steel, cover thickness can be reduced, extending deck life from ~30 years to 75+ years.
Comparison: Steel vs. GFRP Rebar
| Propriedade | Barra de aço | Vergalhões de PRFV |
| Resistência à tracção | 400–600 MPa | 600–1200 MPa |
| Módulo de Elasticidade | ~200 GPa | 45–60 GPa |
| Resistência à corrosão | Baixo | Excellent (100%) |
| Peso | 1.0 | 0.25 (4× lighter) |
| Vida útil | 30–50 anos | 75–100 years |
| Cost per unit weight | Mais baixo | Slightly higher |
| Lifecycle Cost | Higher (due to repairs) | Lower (maintenance-free) |
Saber mais:
- Vergalhões de PRFV vs. vergalhões de aço: comparação técnica
- Vergalhões de PRFV vs. Aço: Custo, Resistência e Benefícios a Longo Prazo na Construção Moderna
- Vergalhões de FRP vs. Vergalhões de aço
Compliance & Certification
To use GFRP rebar in U.S. projects, suppliers must provide:
- ASTM D7957 certificates for material compliance.
- ICC-ES Evaluation Reports (ER) under AC454.
- DOT approvals (e.g., FDOT APL, TxDOT, Colorado DOT).
Benefits for U.S. Market
- Longer lifespan for infrastructure (bridges, highways, marine).
- Reduced maintenance budgets for municipalities.
- Alignment with sustainable construction goals and federal infrastructure programs.
Conclusão
ACI 440.11-22 has made the use of GFRP rebar fully recognized in the United States, giving engineers confidence and contractors a competitive advantage. With corrosion-free performance, longer service life, and compliance with U.S. codes, GFRP is not just an alternative — it is the future of reinforced concrete.
If you are a U.S. engineer, contractor, or investor looking to adopt GFRP rebar in your projects or set up a production facility, contact Composite-Tech today. We provide world-leading equipment for GFRP rebar and mesh production, full training, and support with certification.
Perguntas frequentes
Is GFRP rebar approved by ACI?
Yes, ACI 440.11-22 is the official design code for GFRP in the U.S.
Can I use fiberglass rebar in residential foundations?
Yes, ACI 440.11 covers footings, slabs, and walls. Always verify local building code acceptance.
What is the lap splice length for GFRP?
Typically 40–60 bar diameters, depending on bar size and surface finish.
Is fiberglass rebar fire resistant?
It has lower fire resistance than steel; additional measures are needed in high-temperature environments.
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