A frame cabin question

[Akeee]

Hello everyone and thank you for trying to help me!
I have to design a simple a cabin frame like this one (the same model):

http://i6.photobucket.com/albums/y223/EaglesSJ/P1040221.jpg

So i begin with wind load evaluation, and i distributed the load for every rafted beam. Everything looks fine but i have one big questions: i look at the top of the rafter connection, and is a long horizantal beam, ridge board i think is called, that supports the rafters from the left and the right side. At the buttom of the rafter is over the beam with wood cut like this:

http://i6.photobucket.com/albums/y223/EaglesSJ/P1040214.jpg

. So i wanted to calculate the bending moment so i can design the cross section, but i dont know to evaluate the type's of supports, with one of this:

http://www.constructionknowledge.ne...es_gen_tech_knowledge/structural_supports.gif

it is ? I think and at the top is roller support ( 1 horizantal reaction) and down is pi support. It's corect?
How can i improve the support types so it can take better wind lateral load ?
Thank you very much

 

[msquared48]

I would design the bottom support of the rafters as a pin connection as you can get a suction load on the leeward side of the rafters in a good wind. So put a tension tie as needed (does not have to be at every rafter) back into the floor structure from the rafters.

Mike McCann
MMC Engineering