guyed tower dynamics

[JWB46]

Hi guys (no pun intended)

I have been reading up on guyed tower dynamics - lots of literature - excellent treatment given in 'Cable Structures' by Max Irvine. However, when I try to rework his Example 4.3 while my guy stiffness results agree pretty well with his and the mode shapes are exactly the same, my natural periods are different - I suspect an error in the book. Anyone had similar experience ?

 

[JoshPlumSE]

The first thing to look at here (in my experience) is whether you were using the WEIGHT or the MASS for your period calculations.

If this were messed up, then you'd be off by about a factor of sqrt(g)..... I've encountered this same mistake more times than I can count.

Josh

 

[JWB46]

Thanks Josh,

No, I'm not confusing weight and mass, though it's a common mistake as you rightly say ! I am using the data given in the book.

Thing is, the result in the book looks suspicious anyway: a fundamental period of 0.43s for a 120m tall tower.

 

[VoyageofDiscovery]

It has been a long time but I remember that the formula for k dynamic in the book is incorrect.

HTH

 

[JWB46]

Thanks for replying. Yes, you are quite right there are typo's in several of the equations for K but I have sorted that out. The K values used for the example in the book are more or less correct.

I have contacted Prof Irvine to see what he says and will post his reply in due course.