FRP Calculator for Beam, Load & Section Properties
Preliminary global-beam screening for pultruded FRP: bending, average shear, Timoshenko-corrected deflection, environmental reductions, and steel/aluminum equivalence. Method-specific datasets prevent incompatible standards combinations. Free, no login.
Run the section check, then carry the shape, load case, environment, and destination into the RFQ.
Material dataset: Illustrative inputs for ASCE/SEI 74-23 screening — qualification data required · Screening basis: Preliminary global beam screen using ASCE/SEI 74-23-style φ and live-load γ_Q; not a complete code check and λ is not modeled · Env knockdown: ×0.85 (Long-term UV + moisture exposure)
Reference: EN 13706-3 · GB 50608-2020 / T/CECS 692-2020 · ASCE/SEI 74-23 · CEN/TS 19101:2022 · ASTM D3917. Calculator performs global bending (vs min tensile/compressive strength), average shear, and load-case-matched Timoshenko deflection only. Not modeled: local buckling, lateral-torsional buckling, web crippling, long-term creep deflection, the ASCE 74-23 time-effect factor λ, principal-axis bending of single angles, and connection design — these require dedicated analysis; contact F1 Composite engineering.
How to use the FRP calculator for profile sizing
Prefer precomputed numbers? The FRP span tables publish the allowable uniform load for every standard I-beam, channel, and tube over 1–6 m spans on the same design basis — each row opens here pre-loaded for verification. And once a section passes, the pultruded profile price estimator gives you its budgetary USD/meter range before you send the RFQ. Compare the passing section with our fiberglass structural shapes catalog before specifying the final size.
This calculator screens three recurring questions in FRP profile selection: global bending, average shear, service-load deflection, and first-pass steel/aluminum equivalence. The ASCE-, CEN- and GB-oriented options apply a limited subset of factors to compatible input datasets; they are not full implementations of those standards. Local and lateral-torsional buckling, creep and time effects, web crippling, connections, complete load combinations, bracing, and system stability remain outside the model.
Input example — walkway beam
The Walkway preset loads a 3 m simply supported I-section with a 5 kN/m service UDL. It uses the illustrative balanced-GFRP dataset paired with the ASCE-oriented preliminary factors and outdoor exposure. The result is useful for eliminating clearly inadequate trial sections and seeing whether global strength or deflection governs; it is not an ASCE design release, and the material properties must be replaced with project qualification data.
How to interpret the results
- Deflection almost always governs. FRP E_L is 17–28 GPa — roughly 1/10 of steel. Members sized for steel-equivalent strength deflect about 10× more. Check L/240 or L/360 first; if it passes, the bending and shear checks usually pass too. The Timoshenko shear-deflection share (shown below the load summary) is non-trivial for short-span beams because FRP G_LT is only ~1/6 of E_L.
- Equivalent section is deeper, not heavier. Replacing a W6×12 (152×76) steel beam at equal stiffness needs roughly ×1.7 on every dimension under geometric scaling (≈ 265 mm deep) and still lands ~25–30% lighter. Practical replacements deepen the web instead of scaling every wall, which is how optimized FRP substitutions reach 40–60% weight savings — the equivalence tab shows the conservative geometric-scaling figure.
- Why allowables look low. Allowable strength = φ × min(F_tL, F_cL) × Ω_E — pultruded FRP typically fails on the compression face first, so the lower compressive strength governs bending. The resistance factor (φ_b = 0.65 in ASCE/SEI 74-23, 1/γ_M ≈ 0.67 in CEN/TS 19101, 1/γ_R ≈ 0.63 in GB 50608) covers material and manufacturing variability; Ω_E (0.70–1.00) adds long-term environmental knockdown for outdoor/wet/hot/chemical service. Long-term creep and the ASCE 74-23 time-effect factor λ are separate checks the calculator does not model. Together these explain why the design allowable is 25–40% of the characteristic strength reported by the material spec.
Common specification mistakes
- Using steel allowables for FRP. FRP must never be designed using AISC 360, Eurocode 3, or GB 50017 steel allowables. Pultruded profiles follow ASCE/SEI 74-23 (US), CEN/TS 19101:2022 (Europe), or GB 50608-2020 with T/CECS 692-2020 (China). All three use distinctly different resistance factors and explicitly cap long-term stress at 20–35% of ultimate.
- Ignoring local buckling. Thin-walled FRP sections can buckle locally before reaching calculated bending capacity. The calculator flags an outstanding-flange b/t advisory (limit ≈ 18 for E-glass pultruded), but a full check per ASCE/SEI 74-23 Ch.3 or CEN/TS 19101 §6 is still required — for compression-governed members the limit tightens further.
- Treating FRP as isotropic. Pultruded FRP is strongly orthotropic: longitudinal tensile strength (F_tL) is 4–5× the transverse value, and E_T is only 25–35% of E_L. Connections that load in the transverse direction (drilled holes, notches, brackets) need special detailing per ASCE/SEI 74-23 Ch.8 or T/CECS 692-2020 §7.
- Skipping shear deflection. Because G_LT is only ~3 GPa, FRP shear deflection typically contributes 5–15% of total mid-span deflection at common span-to-depth ratios — and over 20% on very short spans (L/h ≲ 10). The calculator applies a load-case-matched Timoshenko correction on the shear area automatically and reports the shear share — pure Euler-Bernoulli (Δ = 5wL⁴/384EI) under-predicts.
Referenced standards
- EN 13706-2/-3:2002 — Reinforced plastic composites — Pultruded profiles — General requirements and Specific requirements (E17 / E23 minimum-modulus grades)
- ASTM D3917 — Standard Specification for Dimensional Tolerance of Thermosetting Glass-Reinforced Plastic Pultruded Shapes
- ASCE/SEI 74-23 — Standard for the Load and Resistance Factor Design of Pultruded Fiber Reinforced Polymer Structures (2023, supersedes the 2010 ACMA Pre-Standard)
- CEN/TS 19101:2022 — Design of fibre-polymer composite structures (Eurocode-track Technical Specification preparing prEN 19101)
- GB 50608-2020 — Technical Standard for the Engineering Application of Fiber-Reinforced Composite Materials
- T/CECS 692-2020 — Technical Regulation for Structures of Pultruded Profiles
- Eurocomp Design Code and Handbook — Structural Design of Polymer Composites (companion to CEN/TS 19101)
Frequently Asked Questions
Is this FRP profile calculator free?
Yes. The FRP profile calculator is fully free, runs in your browser without login or sign-up, and is available worldwide. F1 Composite publishes it as an engineering reference for specifiers selecting pultruded FRP profiles.
Which standards does the FRP calculator follow?
It is a preliminary global-beam screening tool, not a complete standards compliance calculation. The method selector applies simplified resistance and live-load factors oriented to ASCE/SEI 74-23, CEN/TS 19101:2022, or GB 50608-2020, plus a legacy ASD screen. Each method now exposes only its compatible material dataset. The tool does not perform local or lateral-torsional buckling, creep/time-effect, web crippling, connections, load combinations, system stability, or project-specific qualification checks, so a licensed engineer must complete the applicable code design.
Does the calculator handle orthotropic FRP properties?
Yes. For every FRP grade the calculator reports the longitudinal modulus E_L (fiber direction), transverse modulus E_T (typically 0.25–0.35 × E_L for E-glass pultruded), in-plane shear modulus G_LT (typically 3–4 GPa), and both tensile and compressive strengths (bending is checked against the lower of the two). Deflection includes a load-case-matched Timoshenko shear correction driven by the E_L / G_LT ratio — typically adding 5–15% at common span-to-depth ratios, and more on very short spans (L/h ≲ 10).
How are environmental knockdowns applied?
FRP characteristic strengths are multiplied by an environmental factor selected from the dropdown: 1.00 indoor dry, 0.85 outdoor exposed (UV + humidity), 0.80 wet / immersion, 0.75 mild chemical exposure (per T/CECS 692-2020 Annex), and 0.70 elevated temperature 30–60°C (approaching glass transition per ASCE/SEI 74-23 §3.5.4). Metals are unaffected. For acid resistance class selection, see T/CECS 692-2020 Annex.
Can I use this calculator for vinyl ester, polyurethane, or phenolic FRP profiles?
The EN 13706 E17/E23 and GB 50608 Class I/II material properties reflect E-glass / polyester pultruded profiles. Vinyl ester and polyurethane FRP have similar modulus and slightly different strength; phenolic FRP has lower modulus and significantly better fire performance. For non-default resin systems, contact F1 Composite engineering for project-specific characteristic values.
Does this calculator handle local buckling, lateral-torsional buckling, and connections?
Not as full design checks. The calculator flags a wall-slenderness advisory per shape — outstanding flanges and angle legs at b/t > 18, box flat widths and tube D/t at > 40 (E-glass pultruded typical) — prompting a dedicated local-buckling review per ASCE/SEI 74-23 Ch.3 or CEN/TS 19101 §6. Lateral-torsional buckling, web crippling, single-angle principal-axis bending, long-term creep, and bolted/bonded connection design (ASCE/SEI 74-23 Ch.8) are out of scope — these need a dedicated tool such as PulCalc 3.x or project-specific engineering. F1 Composite engineering supports these checks on request.
Why does FRP need a deeper section than steel for the same deflection?
FRP elastic modulus is 17–28 GPa versus steel's 200 GPa — about 1/8 to 1/10 of steel. To match steel's deflection, the FRP section needs roughly 8–10× the second moment of area, achieved by going deeper (stiffness scales with depth cubed). The FRP replacement is still lighter because FRP density is 1.9 g/cm³ versus 7.85 g/cm³ for steel: ~25–30% lighter under uniform geometric scaling (the calculator's conservative figure), and 40–60% lighter when the section goes deeper rather than uniformly larger.
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APA
F1 Composite. (2026). FRP Profile Engineering Calculator [Web application]. Chongqing F1 Composites Co., Ltd. https://www.f1composite.com/frp-profile-calculator
MLA
F1 Composite. “FRP Profile Engineering Calculator.” Chongqing F1 Composites Co., Ltd., 2026, https://www.f1composite.com/frp-profile-calculator.
BibTeX
@misc{f1composite_frp_calculator_2026,
author = {{F1 Composite}},
title = {FRP Profile Engineering Calculator},
year = {2026},
howpublished = {\url{https://www.f1composite.com/frp-profile-calculator}},
note = {Web application}
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