range of widths for steel joists
range of widths for steel joists
(OP)
I'm trying to find out the probable chord widths for steel joists (K, LH, & DLH). I understand that these will vary depending on the steel angle sizes (plus the gap between the 2 angles) used for the chords for each steel joist type. Therefore, I'm looking for ballpark ranges for each joist type.
If this info is not available, can someone tell me what the range of angle sizes used for each joist type. Say, for K joists, the angles should vary from 1"x1" to ?. I'm guessing that K-joists angle sizes starts from 1". What about the LH and DLH? thanks!
If this info is not available, can someone tell me what the range of angle sizes used for each joist type. Say, for K joists, the angles should vary from 1"x1" to ?. I'm guessing that K-joists angle sizes starts from 1". What about the LH and DLH? thanks!






RE: range of widths for steel joists
RE: range of widths for steel joists
1) Call a few manufacturers and get a size of the top chord. Then spec it out on the drawings.
2) Size the chord myself using engineering principals and angle sizes found in the AISC Then set the chord width on the drawings. I believe most manufacturers use angles with Fy =50ksi, but I'm not 100% sure about this. Since joists are bough by their weight this process shouldn't increase costs that much.
¾" to 1" are standard gap sizes for K series joists (from what I have seen). I'm not sure about LH or DLH joists.
RE: range of widths for steel joists
RE: range of widths for steel joists
The chord angles employed have consistently been equal legged angles, leg lengths generally varying in 1/2" increments.
Leg thicknesses vary by the hundredths of inches and vary among manufacturers depending on the economic calculus of their engineering and supply and customer base.
The top chord angles may be larger than the bottom chord angles due to the section requirements of the combined stresses in the top chord ie axial + compression.
The largest angle employed, I have been told is 8x8 (Vulcraft, Quincy), making for a 17" net width chord, and this was for a 100+/- roof joist(if I recall the length correctly) also supporting a very large seismic drag load.
5" net width, utilizing 2x2 top chord angles with a 1" gap is very very common. 6" and 7" is not uncommon and may occur in an otherwise 5" top chord width bay where special point loads are added to a joist, such as from fire sprinkler main loads or HVAC unit loads or other.
Happy New Years!
RE: range of widths for steel joists
I don't know what has motivated you to raise this question, but I doubt there is direct answer to it, as the member sizes are results of design by the joist manufacturers under the guidelines set by SJI. The attached paper laying out the general process, and responsible parties for such design. You might gain some idea where to get help you were seeking.
By the way, please ignore my previous response, which was a complete mistake by not understand your question.
RE: range of widths for steel joists
RE: range of widths for steel joists
RE: range of widths for steel joists
Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask
RE: range of widths for steel joists
I hope this helps!
Approximate Joist Information
compiled from catalogs, manufacturer's data and field data
Joist Web Web Web Web Chord Chord
Depth Panel Panel End End Width Width
Min. Max. Min. Max. Min. Max.
H or K-series (not including joist chords with cold rolled hat sections)
8 14 24 12 34 2.50 3.50
10 14 24 12 34 2.50 4.00
12 17 24 14 34 2.50 4.50
14 17 24 15 34 3.00 4.50
16 18 24 19 34 3.50 5.00
18 20 24 21 34 3.50 6.00
20 22 24 22 34 3.50 6.00
22 24 48 25 50 3.50 6.00
24 24 48 27 54 3.50 6.00
26 24 48 30 56 3.50 6.00
28 24 48 33 60 3.50 6.00
30 24 48 33 66 4.00 6.00
LH-series
18 36 48 14 45 3.50 7.00
20 40 48 16 50 3.50 7.00
24 48 48 20 60 4.00 7.00
28 48 58 24 68 4.00 8.00
32 52 70 28 78 4.50 9.00
36 60 72 32 81 5.00 9.00
40 70 80 36 84 5.00 9.00
44 72 88 40 88 5.00 9.00
48 72 96 44 96 5.00 9.00
DLH-series
52 78 104 48 104 6.00 9.00
56 84 112 52 108 6.00 9.00
60 89 120 56 120 7.00 11.00
64 96 128 60 128 7.00 11.00
68 102 136 64 136 7.00 11.25
72 108 144 68 144 7.00 11.25
Note:
This data has been compiled from information provided by others. There is no guarantee or warranty that this information is accurate.
RE: range of widths for steel joists
RE: range of widths for steel joists
JAE, how is your table correlates to the joist types? Is the table for K-joists only?
RE: range of widths for steel joists
RE: range of widths for steel joists