damping of steel stacks
damping of steel stacks
(OP)
I am designing a steel stack for a client and SMACNA recommends an annular damping pad between the base plate and the footing. They claim that this will damp out any vibrations due to vortex shedding etc. I'm not sure I buy this idea. In the past I've used strakes, large sections, multiple brace points (to change the fundamental frequencies) etc. to avoid vortex shedding effects. All of the literature I've read on the topic suggests these solutions as well as others (such as tuned mass damping) It just seems a little fishy that a little damping pad is going to solve all of the woes due to dynamic vibrations when the vast majority of the literature gives other solutions.






RE: damping of steel stacks
I believe this may be because, they have found fatigue cracking in the area of the base of the stack.
Regards
VOD
RE: damping of steel stacks
I just came across this and thought it might be of some help to you. I have no experience with this method, like you I have alwayed used helical strakes.
ASME STS-1-2000 Steel Stacks
Section 5.3.2 Damping Methods
"Preformed Fabric Pads. The control of damping in a stack is obtained by installing a preformed fabric pad at the base of the stack. --- This will require the addition of a preformed fabric pad(washer) and steel backing plate beneath each anchor bolt nut. This method has been demonstrated to provide a damping value up to approximately 0.03."
RE: damping of steel stacks
Incidentally I looked into it further and contacted a company that designs and provides these and they run about the same as strakes
RE: damping of steel stacks
I am new to stacks. My boss gave me a serie of 3 stacks, that we want to brace to reduce vibrations. Could you please shed some light on that subject. Provide a method if possible or recommend any references. Your answer is appreciated.
Layla Zelnick.
RE: damping of steel stacks