Random Analysis for Wind load

[ThomasH]

Hi all

A question that I have been thinking about lately.

The examples for random analysis that I have seen usually means that the load is given as a PSD-function with unit G^2/Hz. I have seen a couple of tutorioals and examples for this.

But if I instead want to study the random behaviour of wind interacting with a structure. Does anybody know of any examples/tutorials that deals with this?

Any ideas or tips would be appreciated.

Thomas

 

[realtime2]

Probably there are two paths for this answer and it depends on if you are doing an
NVH (noise,vibration, harshness) study or a "Load effects" study. There may be ways to
translate a PSD into a building's vibration, as in Vortex induced Vib., but for that I'm not
a good source of info. If you are doing a loads study PSD is a waste of time. A single sharp
load spike in a series of small sine waves for example, will not have much PSD "power". It just
won't show up, but it will do major damage. You need to generate a real time series
of wind induced loads, apply them and follow the local stresses at all the hot spots.

The offshore folks with their waves often apply a 100 year storm
wave force to their structures, but not in PSD form.
A set of waves of normal height could be characterized by PSD but still one needs to create a
load history to be able to assess the structure. A guy called Swanson did a lot of work with PSD
and fatigue a number of years ago. You should check how he did it. It works ok if there are
no load spikes or mean shifts in the variable amplitude load history, but in the days of terabyte
disk why bother condensing a load history into a PSD? - just run the whole history of loads.

 

[ThomasH]

Hi

Thanks for the ideas. It is a starting point.

My interest is to analyze a structure like a building or a bridge. The analysis is for both vibrations (comfort) and for forces (strength). Today I use a combination of FEM and "handcalculation" (MathCad) but I am curious regarding alternative approaches.

Anyway, thank you for the input.

Thomas