FRP vs steel, aluminum, timber and concrete
Compare materials for the same job: span, loads, deflection, exposure, connections and service period. Use the designed member and installed cost to choose an option; a material property or density ratio is only one input.
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Define an equivalent function before comparing materials
1. Freeze the duty
Use the same span, support conditions, loads, deflection limit, environment and required service period.
2. Design each option
Let each material use an appropriate section and connection. Equal outer dimensions or equal mass do not mean equal capacity.
3. Compare the installed package
Include supports, foundations, fabrication, fasteners, protection, transport and installation access.
4. Review evidence and future work
Match material properties to their basis, then compare inspection, maintenance, replacement and end-of-life assumptions.
What changes when the material changes?
| Review | Pultruded glass FRP | Steel | Aluminum | Timber | Concrete |
|---|---|---|---|---|---|
| Structural behavior | Directional laminate properties; review deflection, creep and connections. | Review grade, section, stability and connection design. | Review alloy, temper, section and welded-zone properties. | Review species, grade, moisture, grain direction and connection details. | Review concrete and reinforcement grades, cracking, creep and detailing. |
| Weight | Use the selected section's published mass and complete BOM. | Use the selected section, coating and connections. | Use the selected section and fabrication details. | Use the designed member size and moisture basis. | Use the designed volume, reinforcement and connections. |
| Exposure | Match resin, surface and cut-edge treatment to chemical and outdoor duty. | Specify a compatible protection system and inspect damaged areas. | Review chloride, galvanic and surface-finish conditions. | Review moisture, decay, insects and required treatment. | Review permeability, cracking, chemicals and reinforcement corrosion. |
| Electrical and thermal duty | Use evidence for the offered material and assembly; conductive additives or hardware matter. | Conductive metal; coordinate thermal breaks, bonding and grounding. | Conductive metal; coordinate thermal breaks, bonding and grounding. | Properties depend on moisture and build-up; qualify the assembly. | Properties depend on moisture, reinforcement and build-up. |
| Fire | Tested formulation and assembly determine applicable performance. | Non-combustible material; member fire resistance still requires design. | Non-combustible material; strength retention and assembly still require design. | Combustibility, charring and assembly design require review. | Section, cover, moisture and assembly determine fire resistance. |
| Whole-life cost | Quote the same function and include inspection, surface care and replacement assumptions. | Include protection, inspection, access and future repair assumptions. | Include finish, connections, inspection and repair assumptions. | Include treatment, inspection, repair and replacement assumptions. | Include inspection, crack repair and access assumptions. |
A defined FRP reference: the published E23-ISO laminate
| Property | Value | Basis |
|---|---|---|
| Density | 1.9 g/cm³ | Published nominal E23-ISO laminate value; not a batch result. |
| Longitudinal tensile modulus | 23 GPa | EN 13706 E23 minimum; EN ISO 527-4 test reference. |
| Transverse tensile modulus | 7 GPa | EN 13706 E23 minimum; EN ISO 527-4 test reference. |
| Longitudinal tensile strength | 240 MPa | EN 13706 E23 minimum; not an allowable design stress. |
| Transverse tensile strength | 50 MPa | EN 13706 E23 minimum; do not replace with the longitudinal value. |
Source: EN 13706-3:2002 Table 1 as documented in F1 technical data. Confirm the offered formulation and applicable reports; these reference values do not certify every catalog section.
Worked example: equal bending stiffness, not equal outer dimensions
Chosen inputs
- Span L = 3000 mm; uniform load w = 1 N/mm (1 kN/m).
- Steel E = 200 GPa; I = 1,000,000 mm⁴. Both are example inputs.
- FRP longitudinal E = 23 GPa, using the E23 grade reference above.
- Bending-only equation: δ = 5wL⁴ / (384EI).
Calculated result
With the same I, bending deflection is 5.27 mm for the steel input and 45.86 mm for the FRP input. Matching EI requires FRP I = 8,695,652 mm⁴, or 8.70 times the example steel I.
A larger I does not identify a suitable section or determine its mass. The next step is to check actual candidate geometries, strength, connections and service conditions.
Excluded here: shear deflection, creep, local buckling, connections, temperature and durability factors, strength checks and self-weight differences. Use the profile calculator for a broader preliminary screen, followed by project engineering review.
Compare costs and environmental impacts for the same installed function
Use dated quotations in the same currency and scope. Include fabrication, supports, installation, inspection, surface care, access, downtime, replacement and disposal where relevant. Record the source of each maintenance interval; a generic coating life is not a site survey.
The life-cycle cost calculator discounts your assumptions over a common study period and can return either material as the lower-cost option. Its example costs are an index, not market prices.
For carbon, compare compatible EPD or LCA data per equivalent installed function, using the same boundaries and service period. Manufacturing, transport, replacement and end-of-life assumptions can change the outcome. This page assigns no generic carbon footprint or environmental winner.
Frequently asked questions
Is FRP stronger than steel?
There is no universal member-level ranking. FRP tensile strength is directional, while steel design may be governed by yielding, stability or deflection. Compare design values and the complete section for the same loads, spans, deflection and connection requirements. A tensile-strength-to-density ratio is not a replacement-member check.
What are the advantages of fiberglass over aluminum?
Glass FRP can offer low thermal conductivity and a compatible nonmetallic solution for some chemical or electrical duties. Aluminum may suit other stiffness, fabrication or fire requirements. Check the actual laminate or alloy, surface, connections and assembly; glass FRP does not resist every acid or alkali.
Can an FRP beam replace a steel beam of the same dimensions?
Only after structural review. Lower elastic modulus can make deflection govern even when a strength comparison looks favorable. Review shear deformation, creep, local buckling, environmental factors and connections as well as bending. The example on this page isolates bending stiffness and does not approve a substitution.
How should I compare FRP with timber or concrete?
Define the same installed function first, then compare designed member sizes, foundations, connections, exposure, fire requirements and maintenance. Material density alone cannot establish the weight or cost of an equivalent structure. Timber grade and moisture, and concrete reinforcement and cracking, belong in the comparison.
Does FRP always have the lowest life-cycle cost or carbon footprint?
No. Cost depends on actual quotations, installation, inspection, maintenance, access, replacement and discount assumptions. Carbon comparisons need compatible EPD or LCA boundaries for the same function and service period. Neither result follows from the material name.
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