Engineering guide
The EN22 module calculates wind loads for vertical cylindrical vessels to DIN EN 13445-3 clause 22. If you want to calculate the wind load on a column or a vertical vessel, you must capture not only the basic shell but also the attachments: ladders, partial and full platforms, walkways and vertically routed parallel piping increase the exposed area and change the aerodynamic coefficients. The module models these configurations, including the mutual interference of adjacent circular cylinders arranged in a row, as occurs with closely spaced columns or outdoor tube bundles.
The calculated wind loads are prepared as distributed loads and resulting moments over the vessel height and feed the load cases of the EC1 module (load case superposition to EN 13445-3). There they are combined with dead weight, internal or external pressure, snow loads and other actions, so that the complete stability and strength verification of the column results. Wind load calculation for vertical equipment is thus covered end to end, from the exposed area to the superposition of internal forces.
In practice, this verification is required for every column erected outdoors and every tall vertical vessel; the wind load there frequently governs the wall thickness of the bottom course, the anchorage and the foundation loads.
Scope
- Wind loads
Typical workflow
Define site and wind parameters
The basis is the wind conditions at the erection site: basic wind speed or velocity pressure, terrain category and the height distribution of the dynamic pressure. These quantities come from the national wind load rules and enter the calculation as a profile over the vessel height.
Record vessel geometry and attachments
The cylindrical shell is described by diameter, height and insulation. The attachments are then configured: ladders, partial and full platforms with their elevations, walkways and vertically routed parallel pipes. Each element increases the effective wind-exposed area.
Determine aerodynamic coefficients
For the cylinder, the force coefficient is determined as a function of slenderness and surface roughness; separate coefficients apply to attachments. For adjacent circular cylinders arranged in a row, the method accounts for the mutual interference, which can increase the loading compared with an isolated cylinder.
Calculate the wind load distribution
From the dynamic pressure profile, areas and coefficients, the distributed wind loads over the height are obtained, together with the resulting shear forces and bending moments at the governing sections, in particular at course welds and at the base fixity.
Hand over load cases to EC1 and superimpose
The wind loads are handed over to the EC1 load case module and combined there with dead weight, pressure, snow and additional loads into the governing load combinations for operation, testing and erection. The internal forces for the strength verification of the shell and the anchorage are then available.
Frequently asked questions
Why is it not sufficient to consider only the bare cylinder of the column?
Ladders, platforms, piping and insulation cladding increase the exposed area considerably and in part have markedly higher force coefficients than the smooth circular cylinder. For fully equipped columns, the attachments' share of the total wind load can be of the same order as the cylinder load. Neglecting the attachments systematically underestimates bending moments, anchor forces and foundation loads.
What is the effect of arranging adjacent cylinders in a row?
If several circular cylinders stand close together in a row, their flow fields interact: depending on the spacing ratio, shielding but also nozzle effects and increased coefficients can occur. The method of EN 13445-3 clause 22 captures this via surcharges depending on the centre-to-centre spacing. For very close arrangements or groups beyond the standard's scope, wind tunnel data or specialist literature must be consulted.
How are EN22 and EC1 related?
EN22 determines the wind loads and their distribution over the height; EC1 handles the load case superposition: there, wind is combined with dead weight, internal or external pressure, snow and other loads in the combinations required by the standard, and the shell is verified at the governing sections. This separation makes it possible to change wind configurations without rebuilding the rest of the load case structure.
Do vortex-induced cross-wind vibrations have to be investigated in addition?
The static wind load calculation covers the loading in the wind direction. Slender columns, however, can be excited to vibrate across the wind direction by vortex shedding, especially at high slenderness ratios and low damping. This verification is carried out to the relevant wind load rules (EN 1991-1-4) and may require structural measures such as helical strakes (Scruton spirals) or guying.
Technical content source: LV-Solved-Problems-Content 628d313247e7