Transfer force - Connection Design 1

[IDSolutions]

I am designing column beam brace connection and would like to clarify on Transfer force listed on the design document (attachment). I know the beam to column connection should be designed for shear load = Vb+Rb and axial load = transfer force + Hc. I am missing something in this? Also why do we have different transfer forces listed on two sides of same column? Should all the beam-column connection along that elevation be designed for this transfer force?..Thanks....

 

[klaus.]

well maybe the live load on the beam is different on both sides ...who knows



best regards
Klaus

 

[IDSolutions]

So do I design the connection on each side of column for the individual force shown or both connections (same column) for higher of two forces?

 

[KootK]

I'm also confused by the transfer forces being different on the opposite sides of the same column. My first choice would be to call the EOR and get an explanation. As an alternative, I'd think that you'd be conservative in designing for the higher of the two forces.

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.

 

[IDSolutions]

I talked to the EOR and according to her the transfer load is different on both sides of column (as indicated on the drawing) so nutshell design each connection for the axial load shown on the drawing in the rectangular box with min value 100kN. Now I am little stuck with the vertical brace between grid 03 and 04. The horizontal W stringer has an axial load of +/- 800kN in addition to the loads introduced by vertical brace. I am having difficulty trying to configure this connection because (a) Strong axis moment connection requires transverse as well as web stiffeners (b) large axial load (800kN + 100kN min) for beam to column connection in addition to all the other loads induced by vertical brace. I am inclined towards connection the brace to beam only (special case 3) due to acute angle. Can somebody look at the attached calculations and suggest if it can be done this way? I have attached calculations for the interface connections only. Hope somebody shines a light on it. Thanks...

 

[WillisV]

EOR does not appear to know the definition of a transfer force.

 

[IDSolutions]

I think WillisV and I are in the same page. My understanding always was that transfer force pass from one side of column to the other side so equal in magnitude. But EOR doesn't appear to think so. Any suggestions on the attached calculations...

 

[KootK]

Nice looking detail and calcs. Seriously. Some comments:

1) This is not a special (seismic) concentrically braced frame is it? I'd assume not given the choice of angle bracing.

2) The concept, in general, seems fine. Not sure that you really even have much choice without moving the work point.

3) I didn't see any gusset plate compression buckling checks. Presumably, the braces go into compression. Perhaps you simply haven't gotten to that yet or just didn't post it.

4) This strategy imposes a significant moment and shear on the end of the beam that the EOR may not have anticipated. Somebody should check it.

5) By welding the beam flanges to the column stiffeners, presumably for axial transfer, you've created a stiff moment connection between the beam and column. Was that the EOR's intent?



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.

 

[BAretired]

I think you need to obtain clarification of the EOR's requirements. It isn't clear from her drawing.

BA

 

[IDSolutions]

Thanks for the response fellows. I will inquire this further with EOR first thing tomorrow morning. In the mean time answering some of Kootk comments..there is no seismic requirement. It is pipe rack structure so lateral loads are very high in some structures (this one as well). I am running out of options due to small beam and column section used. Not much choice there to transfer such high axial loads thru the connection. I haven't got to the gusset buckling and other checks (on the list) but first wanted to get an opinion whether this configurations was even allowable. I know by welding the beam flanges to column transverse stiffeners it is introducing intended moment but that seemed like a reasonable choice to carry moment and axial load thru the connection.