Observation Platform
Observation Platform
(OP)
I'm designing an observation platform that will be supported on three steel pipe columns and be about 30 feet up. In plan, the columns form a triangle with 4 foot sides. I've derived the wind loads but I've bumped these up to be about 10% of the dead load in my prelim analysis because I want the tower to feel stiff.
My questions are:
a) what's the best way to have a greater confidence that the structure will 'feel' sturdy to the people up there? I can look at vertical vibration, but my bigger concern is people moving in a way to get the tower rocking.
b) Is there a frequency associated with people on a platform that my structure should be designed around?
Thanks.
My questions are:
a) what's the best way to have a greater confidence that the structure will 'feel' sturdy to the people up there? I can look at vertical vibration, but my bigger concern is people moving in a way to get the tower rocking.
b) Is there a frequency associated with people on a platform that my structure should be designed around?
Thanks.






RE: Observation Platform
The period can give you a feel if people moving laterally can get it to oscillating.
The higher the frequency the better of course. Not sure what would be an adequate threshold though.
RE: Observation Platform
RE: Observation Platform
RE: Observation Platform
I (my software) can calculate frequency of the structure:
mode #1: 3.1 Hz
mode #2: 6.0 Hz
I find that I can increase the frequency (reduce the period) by changing the size of the diagonal members I've modeled. Now I just need to decide whether I want to do this.
RE: Observation Platform
Mike McCann
MMC Engineering
http://mmcengineering.tripod.com