Wind Perpendicular to Structure
Basic velocity vb = 25.0 m/s
Basic velocity pressure qb = 0.39 kN/m²
Peak velocity pressure
Force coefficient cf for lattice structures:
Determination of Force Coefficient cf,0 for Lattice Structures Without End-Effect Using Solidity Ratio φ
Solidity ratio:
where
A is the sum of the projected areas of members,
AC = l ⋅ b is the enclosed area of the considered face,
Area ratio of the lattice:
Solidity ratio:
After the solidity ratio is obtained, the force coefficient cf,0 of 1.6 can be read off the standard EN 1991‑1‑4, Figure 7.33 [1], for example.
It is also necessary to define the effective slenderness of the structural component in order to determine the end‑effect factor Ψλ.
Effective Slenderness λ (Table 7.16 → BS EN 1991‑1‑4 [2])
Using the previously calculated values, the end-effect factor Ψλ of 0.95 can be read off the diagram in Figure 7.36 of the standard.
Using this factor, the following force coefficient is obtained:
Calculation of Resulting Wind Load of Lattice Structure
Option 1: Equivalent Static Load Fw
where
Aref is the projected area
Option 2: Load as Member Loads from Area Load
In order to distribute this area load in RFEM/RSTAB to the members only, it is necessary to select the "Empty, on members only" option under Area of Load Application. After entering the load and clicking [OK], the sum of the load to be applied is displayed again in an information window.
