Support Post

banctecbobn

Quick question...

Does anyone know how much weight a steel 27 ft tall 4" square tubing/post with a 1/4" thick wall would support ? Post installed vertically with plate welded on each end. Installing post from basement thru two floors to support a girder truss for the roofing trusses. The truss engineer said the post would support the load but he was shooting from the hip when I asked him.

Have a great day,
Bob

Bob Kovacs

The AISC manual stops listed allowable loads for a 4x4x1/4 column at an effective length of 25'- beyond that, the ratio of length to radius of gyration is too high. In other words, unless the floor systems will adequately prevent sideways movement of the column to effectively create three "shorter" columns, the 4x4x1/4 shouldn't be used.

You need to have a structural engineer properly size this column- not the truss engineer.

Bob

banctecbobn

Bob,

What was the weight the 25 foot long post would support? The post can and is somewhat supported at the 9 foot and then the 19 foot section starting from the bottom. Post is supported where it enters the floor of each level.

Have a great day,
Bob

joasis

There is more to it then just reading the load tables...for instance, grade of steel, ect. My book shows max height allowable of 18 feet for 1/4 wall. Since my reference is regarding wall columns and mezanine supports, it wouldn't apply, but if you have any doubt, and you have a specific reason to use a 4x4 tube, size up to a 3/8 wall which increases load factors by 45% or so. FYI, when we use 4x4 steel, 3/8 wall in a steel building, the actual load doesn't exceede 3 kips.

Kingring

Hey Guys, I am new to this site. Was looking for a forum type site to discuss future inovations in construction, whats going on around the country with all the storm devastation and general work issues. I will check in occassionaly for those who want to talk work. LOL. Anyway, Hello to all in the industry!