ruane
Structural
- Nov 6, 2018
- 3
I have a few questions regarding the fabrication of single angle welded steel trusses that I hope members can help with, offer some advice or comment from past experience:
1. The South African Institute of Steel Construction Greenbook (structural steel connections) suggests that when fabricating trusses with single angle chords and webs, that a full gusset should be used instead of a plate welded to the toe of the vertical leg of the top/bottom chord. See sketch attached. The reason for this is that "it is expensive and difficult to weld on toe plate correctly and ensure quality". I'm not familiar with ASCI codes - do the ASCI codes say anything about this? I've seen some examples in ASCI docs with double angles and toe plate. My preferred choice for a single angle connection is to have a full gusset welded to the chord. What are your thoughts?
2. Consider a girder with a parallel flanged channel top and bottom chord with web horizontal. PC size is 180x70 - flange width = 70 mm. Internals are L100x100x8 (single equal leg angle with dims in mm). Initially it was considered to weld a gusset onto the web of the channel so that the centroid of the angles line up with centroid of the channel when viewed on a section through the girder, but the position of the gusset would mean that the load is not transferred through the centroid of the channel. A revised option is to weld a gusset (also stiffener) between the flanges of the channel to which the vertical can be welded. A second gusset T'd to this stiffener and extending lower down will pick up the verticals. Viewed in plan/section, the centroids of the vertical and diagonal webs won't line up with the centroid of the channel, but the gusset that the diagonal is welded to will line up with the centroid of the channel and vertical. Thoughts/comments on this?
Any red flags?
1. The South African Institute of Steel Construction Greenbook (structural steel connections) suggests that when fabricating trusses with single angle chords and webs, that a full gusset should be used instead of a plate welded to the toe of the vertical leg of the top/bottom chord. See sketch attached. The reason for this is that "it is expensive and difficult to weld on toe plate correctly and ensure quality". I'm not familiar with ASCI codes - do the ASCI codes say anything about this? I've seen some examples in ASCI docs with double angles and toe plate. My preferred choice for a single angle connection is to have a full gusset welded to the chord. What are your thoughts?
2. Consider a girder with a parallel flanged channel top and bottom chord with web horizontal. PC size is 180x70 - flange width = 70 mm. Internals are L100x100x8 (single equal leg angle with dims in mm). Initially it was considered to weld a gusset onto the web of the channel so that the centroid of the angles line up with centroid of the channel when viewed on a section through the girder, but the position of the gusset would mean that the load is not transferred through the centroid of the channel. A revised option is to weld a gusset (also stiffener) between the flanges of the channel to which the vertical can be welded. A second gusset T'd to this stiffener and extending lower down will pick up the verticals. Viewed in plan/section, the centroids of the vertical and diagonal webs won't line up with the centroid of the channel, but the gusset that the diagonal is welded to will line up with the centroid of the channel and vertical. Thoughts/comments on this?
Any red flags?
