Steel Joist
Steel Joist
(OP)
In an existing building there is a floor supported by 20K4 @ 2'-6" span 29' steel joist and metal deck type s. The owner propose to move to that floor 6 legal lateral files (5 drawers). The files will be located perpendiculars to steel joists. I figure out that the files fully loaded weight will be 375 pounds in 20 inches of width (width of lateral files). I divide the 375 pound over the span of the steel joist and give me an additional 13 pounds per linear foot of dead load. I have the following loads estimated
Dead load = 7.6 pounds steel joist weight + 93.75 pounds steel deck and concrete + 50 pounds utilities (partitions, ac, sprinklers, etc.) + 13 pounds files = 164 pounds per ln ft
Live load = 125 lbs/ln ft office use (50 lbs/ft2 x 2.5' tributary area)
WU = 1.2 x 164 = 196.8 lbs/ln ft +
1.6 x 125 lbs/ln ft = 200 lbs/ln ft
= 396.8 lbs/ ln ft < 439 lbs/ln ft LRFD THEN OK
Can anyone check my numbers and give me any suggestions on the calculations procedure.
Any help will be appreciated.
Dead load = 7.6 pounds steel joist weight + 93.75 pounds steel deck and concrete + 50 pounds utilities (partitions, ac, sprinklers, etc.) + 13 pounds files = 164 pounds per ln ft
Live load = 125 lbs/ln ft office use (50 lbs/ft2 x 2.5' tributary area)
WU = 1.2 x 164 = 196.8 lbs/ln ft +
1.6 x 125 lbs/ln ft = 200 lbs/ln ft
= 396.8 lbs/ ln ft < 439 lbs/ln ft LRFD THEN OK
Can anyone check my numbers and give me any suggestions on the calculations procedure.
Any help will be appreciated.






RE: Steel Joist
I still think it's likely manageable since it works out to about a 600 lb point load but top chord localized bending capacity would be my biggest concern.
RE: Steel Joist
Thanks jayrod12
Because the file will be installed diagonal on the floor the location of the load varies at the differents steel joists separated at 2'-6". It varies form mid span to 1/10 of the span length from the support.
How can I investigate the localized bending of the top flange?
RE: Steel Joist
RE: Steel Joist
RE: Steel Joist
RE: Steel Joist
RE: Steel Joist
RE: Steel Joist
Second, I don't like how you spread the concentrated load along the entire length of the joist--as has been stated above, it is a concentrated load, not a uniform load.
DaveAtkins
RE: Steel Joist
RE: Steel Joist
I second this. Draw your loading diagram with the uniform+concentrated load and check the cases with the file cabinet load near mid-span and near the end. I would ignore the live load that occurs where the cabinet is placed because the cabinet is the live load.
For this situation I wouldn't be concerned with localized loads. The cabinet is pretty wide (probably spans close to the full panel width) and you have concrete to further distribute load.
RE: Steel Joist
I recommend going one step further. Draw the shear diagram for the actual loading superimposed on the allowable shear envelope for the joist. The center portion of the joist can resist 15% of the allowable end reaction. Check for any location where the actual shear diagram goes outside the allowable envelope.
DaveAtkins
RE: Steel Joist
RE: Steel Joist
Anyone have a link of the publication by James Fisher for the graphical method.
RE: Steel Joist
Link
Link
I consider this to be the Cadillac document and well worth the $30US: Link
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: Steel Joist
http://www.vulcraft.com/decks/deck-catalog/designi...