Wind loading of members of steel lattice towers - the correct interpretation of EN 50341? 1

[brTCP]

How do you understand the following provision in EN 50341-1 (2012) regarding wind loading applied to members of a lattice tower?

Does it mean that the following figure is correct? Consider the wind blowing along the X-axis. Any thoughts on this?

 

[centondollar]

Wind pressure, like e.g., hydrostatic pressure from water, always acts perpendicularly to a surface. I would say that your figure is correct. The standard could specify "longitudinal member axis" or "lengthwise axis" to be more specific.

The cosine term in the "wind force epxression" might directly give the projected perpendicular value (horizontal wind force projected onto member longitudinal axis) or not - the angle phi_m is surely defined in the standard.

 

[brTCP]

Thanks a lot for your answer @centondollar! I think it maeks sense. I am still confused about the second part of your response though. Here is the definition of the angle phi_m. Does it clarify things for you? To me the definition of the angle seems quite confusing:

 

[centondollar]

At first glance, I am not sure about that definition either. I don't have the standard. Usually, these standards have commentaries which might clarify the terms. A good course of action might be to inquire a colleague about this.