Axial load for rafters
Axial load for rafters
(OP)
When dealing with pitched rafters does anyone here consider the axial load generated by dead weight, snow, and live loadings? Usually, these type beams are handled using a horizontal plane method... which is theoretically incorrect. True, you arrive at the same values for moment but you actually have an axial load per foot of beam as well.
Are the stress interactions typically analyzed or only in beams of a larger span, say 40 or more feet?
Thanks for the input.
Are the stress interactions typically analyzed or only in beams of a larger span, say 40 or more feet?
Thanks for the input.






RE: Axial load for rafters
RE: Axial load for rafters
Thanks.
RE: Axial load for rafters
Collar tie connections are nice if the floor joists and rafters align, but this is not normally the case unless you space the collar ties at 48" on center.
Mike McCann
MMC Engineering
RE: Axial load for rafters
RE: Axial load for rafters
You do have a small axial load in this case but it can be treated as negligible.
For a truss or a roof containing collar ties, I would always take the axial load into account.
RE: Axial load for rafters
RE: Axial load for rafters
When checking your combined loads, compare the design you get with what is provided in the tables in the International Residential Code. These tables can help verify that your design procedures meet standard practice. Just make sure when doing your comparison that you meet all the assumptions made in the use of the IRC tables (ceiling joist location and connections, non-load-bearing ridge, etc.).