Norms · DBN V.2.6-198:2014
DBN V.2.6-198:2014 “Steel structures”: tubes in PV frames
If a frame is made of closed tubes rather than C-channel, the strength and stability of its members are checked to the Ukrainian steel structures code.
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Edition and status
DBN V.2.6-198:2014 with Change 1. Status as of 14.10.2026 per the norms register Solispec checked on 04.10.2026.
The official text: Building norms register, e-construction.gov.ua. Solispec does not host the norm texts. Look for the current edition at the official source.
What it covers
The 42×42×2, 60×60×2 and 80×80×3 tubes used by Solispec are not thin-walled in the sense of clause 3.22, so the code applies to them. Change 1 excludes cold-formed open profiles — they are checked to DSTU-N B EN 1993-1-3:2012 (see thin-walled C-profile).
Design strength and factors
Ry = Ryn / γmThe design strength Ry is the characteristic Ryn divided by the material factor γm (Table 7.1). For other rolled sections and tubes, Table 7.2 gives γm = 1.050. The service condition factor γc = 1.0.
The checks
- Strength: 8.1.1, formula (8.1), and with bending 10.1.1, formula (10.3).
- Compression stability: 8.1.3, formulas (8.3)–(8.5). The buckling factor φ for curve b (α = 0.04, β = 0.09); φ = 1 at a slenderness λ̄ ≤ 0.4.
- Compression with bending in the plane of the moment: 10.2.2, formula (10.6) with φe from Table Zh.3.
φ = 0,5 / λ̄² · (δ − √(δ² − 39,48 · λ̄²)), δ = 9,87 · (1 − α + β · λ̄) + λ̄²For curve b the value of φ from formula (8.4) is capped at 7.6/λ̄² when the slenderness λ̄ exceeds 4.4. For the short legs and struts of a ground frame the cap rarely applies, but for long braces it governs. That is why the free length of a compressed member is worth controlling at layout stage rather than after the calculation.
How Solispec applies it
For a tube frame the Solispec engine takes forces from snow and wind per DBN V.1.2-2:2006 and checks each member against the clauses above. It assigns a closed bent-welded tube to curve b — the section figures in the code’s text are hard to read, so this assignment still needs confirmation. The responsibility factor γn is not applied in these checks.
Terms
- Buckling reduction factor φ (χ)A factor that reduces a compressed member’s resistance for flexural buckling: φ in DBN V.2.6-198, χ in Eurocode 3.
- Thin-walled cold-formed C-profileA bent steel section with thin walls that buckles locally before yielding; it is designed to DSTU-N B EN 1993-1-3:2012.
- Steel partial factors γM and γmFactors that divide the characteristic steel resistance: γ_M per Eurocode for C-profiles, γ_m per DBN V.2.6-198 for tubes.
- Limit design snow load SmThe snow load on the horizontal projection used for strength checks: S_m = γ_fm · S₀ · C under DBN V.1.2-2:2006.
- Limit design wind load WmThe wind load used for strength checks: W_m = γ_fm · W₀ · C, where C covers aerodynamics, height, topography and dynamics.
Other norms
- DSTU-N B EN 1993-1-3:2012: designing C-profiles for PV mountingWhy a perforated 41×41 C-channel is checked to Eurocode 3 rather than DBN V.2.6-198: effective section, γ_M factors, bolts in slots.
- DBN V.1.2-2:2006 “Loads and actions”: what matters for a solar plantThe clauses of the Ukrainian loads code a solar array needs: S₀, W₀, the factors, Changes 1 and 2, and a worked example for Kyiv.
Solispec’s calculation is preliminary: for a design it has to be checked by an engineer. The values and clauses follow the current editions of the norms on the date of the page.