Structural Support
FRP structural support systems use pultruded fiberglass beams, columns, channels, and angles as load-bearing frameworks in industrial buildings where corrosive gases, salt spray, or chemical exposure make steel maintenance impractical. Typical applications include chemical storage buildings, coastal industrial facilities, and corrosive-atmosphere manufacturing plants. This page focuses on where these systems are used. For design strategies, see FRP Lightweight Structures.
In 1984, a chemical company built a small storage building — steel frame, steel purlins, steel siding. By 1990, the purlins at the eave line had rusted through where chlorine-laden condensation collected. They replaced the purlins. By 1996, they did it again. In 1998, a plant engineer asked: what if the building itself didn't rust? That question is now answered by thousands of FRP structural frames operating worldwide.
The environments that destroy steel frames
- Chemical storage and processing buildings: Bulk chemical storage creates indoor atmospheres that are relentlessly corrosive. FRP building frames eliminate the coating cycle entirely.
- Coastal industrial facilities: Salt spray infiltrates building envelopes and corrodes the inside. FRP frames with stainless steel base plates keep the metal component away from the worst exposure.
- Pulp and paper mills: Moisture, sulfur compounds, and chlorine-based bleaching chemicals create an environment that few metals can resist. FRP structural elements have been used successfully since the 1990s.
- Mining and mineral processing: Sulfuric acid plants create acid condensation on structural surfaces. FRP structural frames operate without corrosion protection.
What a pultruded FRP structural frame looks like
| Parameter | Typical Value for FRP | Comparison to Steel (A36) |
|---|---|---|
| Tensile strength (long.) | 207–345 MPa (30–50 ksi) | Comparable to A36 yield |
| Tensile modulus | 17–28 GPa (2.5–4.0 Msi) | ~1/10 of steel |
| Density | 1,700–2,000 kg/m³ | ~1/4 of steel |
| Corrosion resistance | Inherent | Requires coating or alloying |
| Connection type | Bolted (SS or FRP bolts) | Welded or bolted |
| Max service temp | 93–121°C (200–250°F) | 400°C+ (750°F+) |
Deflection governs: FRP is strong but less stiff. Beam depth or span must be adjusted. Connection design is bolted — no welding — and fire-retardant resins achieve ASTM E84 Class 1, though FRP is not non-combustible. Always verify with the authority having jurisdiction.
Where it makes financial sense
An FRP frame typically costs 1.5–2.5 times the first cost of a coated steel frame. But the coating maintenance for steel in a corrosive environment costs 15–25% of the original frame cost every 5–7 years. Over 30 years, maintenance outweighs the FRP premium — often by a factor of two.
"The original steel-framed chemical storage building required full structural repainting every 4 years. The FRP-framed expansion building, completed in 2005, has received zero structural maintenance beyond routine inspection in 18 years."
This page focuses on where these systems are used. For design strategies, see FRP Lightweight Structures.