FRP handrail and guardrail load check
Pick the rule for the site, the post and rail tubes and the spacing. The check returns the post and rail utilisation, the top-rail deflection and the base reactions for the anchors.
- Load rules
- 9
- Markets
- US, EU, UK, CA, AU, NZ
- Post model
- Fixed-base cantilever
29 CFR 1910.29(b)(1)–(5)
- Top edge 42 in (1,067 mm) ± 3 in; 200 lb (890 N) outward or downward within 2 in of the top edge, at any point.
- Under the downward 200 lb load the top rail must not drop below 39 in (991 mm).
- Midrails, screens and intermediate members: 150 lb (667 N). Toeboards at least 3.5 in high, 50 lb.
- Construction sites follow 29 CFR 1926.502(b), which uses the same forces.
0.89 kN at the rail (point load governs), base moment 0.95 kN·m. Bending 105 MPa against 88 MPa.
Characteristic capacity at rail height, without design factors: 2.30 kN, 2.6× the applied load. A without-failure test such as OSHA's sees this margin; the percentages above include the design factors.
43.9 mm under the point load at a post. Post fixed at the base; plate and anchor rotation add to this.
Under the downward load the rail sits at 1059 mm; it must stay at or above 991 mm (39 in).
Service: 0.89 kN and 0.95 kN·m. Factored: 1.42 kN and 1.52 kN·m.
How the check works
Post. The larger of the line load times the post spacing and the concentrated load acts at the top rail. The post is a cantilever fixed at its base, so the base moment is that force times the rail height.
Rail. The top rail spans simply between posts under the line load (wL²/8) or a concentrated load at mid-span (PL/4). Continuous rails do better, so this is conservative.
Strength and deflection. Stresses use the same section properties, material data and design factors as the FRP profile calculator, and deflection includes the shear term that FRP needs.
The requirements behind the load rules are compared in the guardrail requirements guide. Post and rail tubes are listed with the FRP handrail systems.
Frequently Asked Questions
Which guardrail loads does the calculator use?
OSHA 1910.29: 200 lb (0.89 kN) outward or downward at the top rail. IBC 2024 with ASCE 7-22: 50 lb/ft (0.73 kN/m) or 200 lb, not together, and 20 lb/ft in non-public industrial areas with fewer than 50 occupants. EN ISO 14122-3: 300 N/m multiplied by the post spacing with 30 mm maximum deflection. For UK buildings, Canada, Australia and New Zealand you enter the value from the named clause, because it depends on the occupancy category.
Why can a rail meet OSHA and still exceed the screen?
OSHA asks the system to withstand 200 lb without failure, which is usually shown by testing the assembled rail. The screen applies design factors on top: a load factor of 1.6, a resistance factor of 0.65, the time-effect factor 0.8 and the outdoor knockdown. The result panel shows both: the utilisation with design factors, and the characteristic capacity without them. Use a larger post, a closer spacing or test evidence when the screen is exceeded.
What does the calculation leave out?
The base plate, anchors and substrate, the fittings and splices, local buckling of thin walls, and the stiffness of the connections. Posts are treated as fully fixed, so a real rail deflects more. The base reactions are given so the anchors and the supporting steel or concrete can be designed.
Which height and post spacing should I use?
OSHA sets the top edge at 42 in ± 3 in, the IBC at 42 in minimum and EN ISO 14122-3 at 1,100 mm minimum with posts no more than 1,500 mm apart. The F1 catalog handrail systems list a 1,500 mm maximum post spacing and a 1,220 mm maximum height; the project drawing sets both for the rule that applies.