AaronMcD
Structural
- Aug 20, 2010
- 273
This is a discrepancy between my opinion/understanding of AISC Manual/360-10 vs RISA Connection calculations for brace to gusset weld (round tube brace slotted and welded to gusset).
The AISC Manual table J2.5 directs the engineer to section J4 for base metal shear at fillet welds. Section J4 includes elements in tension, shear, compression, and block shear, and specifically applies to elements "such as plates, gussets, angles and brackets."
Manual section 9 states:
The Manual then provides equation 9-2, which essentially sizes the base metal thickness as though shear rupture would occur only along the weld line with no more material beyond the weld line contributing.
It is my interpretation that section J4 and the block shear calculations are applicable to gusset plates, especially considering the section specifically states as much, while more complicated elements like a wide flange section (which obviously will not rupture all the way through at once) can be conservatively analyzed with equation 9-2.
However, RISA Connection checks the brace-to-gusset weld capacity against equation 9-2, effectively checking shear rupture in the gusset without considering the tension zone at the end of the brace.
In the collective opinion of eng-tips (or the one or two who will respond), who is correct?
The AISC Manual table J2.5 directs the engineer to section J4 for base metal shear at fillet welds. Section J4 includes elements in tension, shear, compression, and block shear, and specifically applies to elements "such as plates, gussets, angles and brackets."
Manual section 9 states:
"However, in some cases, the available strength of the connecting element is not directly calculable. For example, while the strength of the beam-web welds for a double-angle connection can be directly calculated, the strength of the beam web at this weld cannot."
The Manual then provides equation 9-2, which essentially sizes the base metal thickness as though shear rupture would occur only along the weld line with no more material beyond the weld line contributing.
It is my interpretation that section J4 and the block shear calculations are applicable to gusset plates, especially considering the section specifically states as much, while more complicated elements like a wide flange section (which obviously will not rupture all the way through at once) can be conservatively analyzed with equation 9-2.
However, RISA Connection checks the brace-to-gusset weld capacity against equation 9-2, effectively checking shear rupture in the gusset without considering the tension zone at the end of the brace.
In the collective opinion of eng-tips (or the one or two who will respond), who is correct?
