Braced frames - connection type for analysis purposes
Braced frames - connection type for analysis purposes
(OP)
Hello guys!
I'd like to find out your opinion about modelling issues of braced frames. As horizontal members of braced frames (girders) are subject to high axial loads, should it be a moment connection between horizontal member and column or not really? I mean, theoritically if we design braced frame we don't need moment connections in it, but when there are huge axial forces in bracing members, how to transfer them onto columns without moment connection? Summarizing: what is a better approach in modelling braced frames- treat all members as axial members only (diagonals and girders) and design connections accordingly or take advantage of massive axial connection due to large axial force and do it as moment connection--> bending moments in horizontal member even out?
Please see the attachement.
I'd like to find out your opinion about modelling issues of braced frames. As horizontal members of braced frames (girders) are subject to high axial loads, should it be a moment connection between horizontal member and column or not really? I mean, theoritically if we design braced frame we don't need moment connections in it, but when there are huge axial forces in bracing members, how to transfer them onto columns without moment connection? Summarizing: what is a better approach in modelling braced frames- treat all members as axial members only (diagonals and girders) and design connections accordingly or take advantage of massive axial connection due to large axial force and do it as moment connection--> bending moments in horizontal member even out?
Please see the attachement.






RE: Braced frames - connection type for analysis purposes
Normally, I would pin the far ends of the beams. Axial transfer capacity alone usually doesn't necessitate fixed connections. That being said, your modelling should reflect the real world detailing. The connection in the photo certainly looks fixed to me.
In an eccentric, seismic application, fixity provides a redundant lateral mechanism (moment frame). If I remember correctly, I think that US codes reward that in the force reduction factor.
The greatest trick that bond stress ever pulled was convincing the world it didn't exist.
RE: Braced frames - connection type for analysis purposes
RE: Braced frames - connection type for analysis purposes
The greatest trick that bond stress ever pulled was convincing the world it didn't exist.
RE: Braced frames - connection type for analysis purposes
Michael.
"Science adjusts its views based on what's observed. Faith is the denial of observation so that belief can be preserved." ~ Tim Minchin