Industrial Platform Design
Industrial Platform Design
(OP)
I am designing an industrial platform to support 1 4000 lb compressor unit in an indoor application (no wind). I am able to brace the frame in the x-y plane with cross bracing. I am not able to brace the frame in the z-y plane as a clear opening is required underneath the platform for forklift access. Please see attached sketch. Three questions:
1) Are the braces to be designed for the resulting forces from the application of a horizontal force equal to 2% of the column load applied to each frame in the x-y plane?
2) In the z-y plane can FR moment connections between beam and column be used in lieu of cross bracing?
3) For (2) above are the design moments for the FR moment connections the resulting moments from the application of a horizontal force equal to 2% of the column load applied to each frame in the z-y plane?
The 2% value referenced above is from Cl. 9.2.5. of Canadian Steel Code which states that "bracing systems shall be proportioned to have a strength perpendicular to the longitudinal axis of the braced member in the plane of buckling equal to atleast 0.02 times the factored compressive force at each brace point in the member or element being braced."
Thanks very much.
1) Are the braces to be designed for the resulting forces from the application of a horizontal force equal to 2% of the column load applied to each frame in the x-y plane?
2) In the z-y plane can FR moment connections between beam and column be used in lieu of cross bracing?
3) For (2) above are the design moments for the FR moment connections the resulting moments from the application of a horizontal force equal to 2% of the column load applied to each frame in the z-y plane?
The 2% value referenced above is from Cl. 9.2.5. of Canadian Steel Code which states that "bracing systems shall be proportioned to have a strength perpendicular to the longitudinal axis of the braced member in the plane of buckling equal to atleast 0.02 times the factored compressive force at each brace point in the member or element being braced."
Thanks very much.






RE: Industrial Platform Design
In an industrial application, the first rule is to make structures robust. Granted, you may not have wind loads. But you have to decide on an appropriate lateral loading condition based on the useage of the platform. Seismic may control, but with forklifts running around, vehicle impact is likely the one to worry about.
RE: Industrial Platform Design
RE: Industrial Platform Design
No contest here, from experience.
No, I was not the driver...
Mike McCann
MMC Engineering
RE: Industrial Platform Design
Thanks,
RE: Industrial Platform Design
To allow for the effects of practical imperfections such as lack of verticality, all structures should be capable of resisting notional horizontal forces, taken as a minimum of 0.5 % of the factored vertical dead and imposed loads applied at the same level.
NOTE For certain structures, such as internal platform floors or spectator grandstands, larger minimum horizontal forces are given in the relevant design documentation.
From AS/NZS1170.0 (Au/NZ loading code) notional lateral load = 2.5% of (G + fcQ).
G = dead
Q = imposed
fc = combination factor which is typically 0.4 or 0.6.
RE: Industrial Platform Design
RE: Industrial Platform Design
RE: Industrial Platform Design
I'd say your bracing design will wind up being based on KL/r(even though the code may not dictate that).
Depending on the length of the braces, and whether or not you are using tension only type bracing a limiting KL/r to 200 or even 300 will probably yeild a pretty robust design. I cannot see actual loading controlling the design.
I see no reason why you can use moment conn.'s in the open ends.
Obviously you want to orient your columns so strong axis bending is in the plane of the open ends for your moment connections.
RE: Industrial Platform Design
...I see no reason why you CAN'T use moment conn.'s in the open ends....
RE: Industrial Platform Design
Do you mean:
1) 1 kPa on the projected vertical area of the x-y plane for design of bracing in the y-z plane, and
2) 1 kPa on the project vertical area of the y-z plane for design of bracing in the x-y plane?
Thanks.
RE: Industrial Platform Design
If it is a reciprocating piston type, you have dynamic forces to consider. Maybe need enertia block and stiffness (both vertical and lateral) to consider to keep structure natural frequency away from the operating frequency.
Could get complicated!
RE: Industrial Platform Design
Yes, the notional load in each orthogonal direction is perpendicular to the surface and parallel to the bracing.
RE: Industrial Platform Design
RE: Industrial Platform Design
10 mph is about 14.7f/s
9000x14.7x14.7/(32.2x2)=30200ftlbs
It looks as though they are figuring on about 3" of crunch.
What is the access? can the forklift get up to full speed. Can you put bollards in to protect the columns?
Michael.
Timing has a lot to do with the outcome of a rain dance.