Eaves tie in portal frames
Eaves tie in portal frames
(OP)
Can someone point me in the direction of information relating to the position where longtitudinal eaves ties can be used in portal frame buildings? (is there a limit of say within d/2 of the bottom of the haunch). If an eaves tie is provided at a higher level (say mid depth of the rafter member) would a stiffener suffice at the bottom of the haunch without struts back to cladding rails?
Thanks for any help.
Vinny
Thanks for any help.
Vinny






RE: Eaves tie in portal frames
RE: Eaves tie in portal frames
What is the purpose of the eaves tie? If you are using it to act as a strut to transfer gable wind loads into the vertical bracing system, then the plane of the tie should correspond with the plane of the horizontal rafter bracing to avoid inducing bending into the minor axis of the portal columns.
If you are designing the frame plastically, and are using the eaves member to restrain the plastic hinge at the underside of the haunch, then you will need to modify the arrangement of the vertical bracing - excellent guidance is given in SCI Publication P252 - see figure 9.9 on Page 57.
It is also worth noting that this document recommends that a torsional restraint is provided at the underside of the haunch whether the frame is desined elastically or plastically - see Section 8.2 on Page 51. I do not think that a stiffener in the compression zone of the eaves moment connection provides the torsional restraint required.
I either provide a hot rolled CHS or position a sheeting rail at this location and use cold rolled angles connected back to the sheeting rail sleeve fixings to provide torsional restraint.
VB
RE: Eaves tie in portal frames
Any thoughts?
Vinny
RE: Eaves tie in portal frames
RE: Eaves tie in portal frames
P252 suggestes that if repositioned, and the vertical bracing arrangement is modified, you can achieve restraint with the eaves tie.
Have a look at P252 and it will all become clear !!
VB