What Is a Carbon Fiber I-Beam?
A carbon fiber I-beam is a structural profile made from carbon fiber reinforced polymer (CFRP), shaped like the letter "I" in cross-section. Like its steel counterpart, the I-shape positions material at the maximum distance from the neutral axis, optimizing the strength-to-weight ratio for bending loads.
Carbon fiber I-beams weigh approximately 80% less than equivalent steel I-beams while providing comparable stiffness and significantly higher specific strength. This makes them valuable in weight-sensitive applications such as temporary bridge structures, offshore platforms, aerospace support structures, and robotic equipment frames.
Carbon Fiber Beam Properties vs Steel
| Property | CFRP I-Beam | Steel I-Beam (S355) |
|---|---|---|
| Density | 1.6 g/cm³ | 7.85 g/cm³ |
| Tensile Strength | 800-1,500 MPa | 355 MPa |
| Elastic Modulus | 100-200 GPa | 200 GPa |
| Specific Strength | 500-940 MPa·cm³/g | 45 MPa·cm³/g |
| Corrosion | Immune | Requires protection |
| Fatigue | Excellent | Good |
| Weight (same stiffness) | 1x | 4-5x |
The specific strength advantage is enormous — carbon fiber beams deliver 10-20 times more strength per unit weight than steel beams. This is why CFRP beams are specified in applications where weight is a primary constraint.
Manufacturing Methods
Pultrusion
The most common production method for CFRP I-beams. Continuous carbon fiber tows are pulled through a resin bath and then through a heated die that shapes the I-profile. The continuous process produces beams with consistent cross-section, high fiber volume fraction (60-70%), and excellent mechanical properties.We manufacture pultruded CFRP plates and strips that can be combined with our structural adhesives to create custom beam profiles when standard I-sections are not available.
Filament Winding
Carbon fiber tows are wound around a mandrel in a precise pattern, then cured. This method allows complex fiber orientations to optimize performance for specific loading conditions. Commonly used for hollow rectangular beams and tubes rather than true I-sections.Hand Lay-Up / Vacuum Infusion
For low-volume or custom applications, I-beams can be fabricated by laying up carbon fiber fabric in a mold and curing under vacuum pressure. This allows maximum design flexibility but with higher labor costs and lower production consistency.CFRP Beam Applications
Temporary and emergency bridges: CFRP bridge beams can be installed rapidly by small teams without heavy lifting equipment. Their light weight allows helicopter deployment to remote locations. Corrosive environments: Chemical plants, wastewater treatment facilities, and marine structures where steel beams corrode rapidly. CFRP beams are immune to corrosion and require zero maintenance. Seismic applications: The low mass of CFRP beams reduces seismic forces on the structure, an advantage when adding floors or extending existing buildings in earthquake zones. Equipment and machinery: Robotic arms, CNC gantries, and precision equipment where low weight and high stiffness improve speed and accuracy.CFRP vs Steel Beams: When to Choose Each
Choose CFRP I-beams when weight is a primary constraint, the environment is corrosive, installation access is limited (no cranes), electromagnetic transparency is required, or maintenance costs must be minimized.
Choose steel I-beams when cost is the primary driver, fire resistance is required without additional protection, connections need to be welded, or the beams will be subjected to high concentrated loads or impact.
Our CFRP Beam Products
While we do not manufacture complete I-beam profiles in stock sizes, we produce the pultruded CFRP plates, carbon fiber fabrics, and structural adhesives that fabricators use to produce custom CFRP beam sections. Our plates provide the flange material (tensile strength ≥ 2,400 MPa, modulus ≥ 160 GPa), and our fabrics provide web reinforcement with full-field bidirectional capability.
View our CFRP plates and fabrics or contact our team to discuss your CFRP beam requirements.