Scarf joint placement... sorry!

[Jpd]

I've searched all I can on here and on the web at large, but I cannot find any prior discussion, so please forgive me.  

30x40 barn, most of the design is finished, i'm placing scarf joints and miscellaneous details.  The attached screenshot is my end bent, with a large door.  The other end has windows.  I'd like to not have more braces so as to keep the center bay open.  Where would you folks suggest scarf joints?  I can get up to 21 foot length, but as the tie beam is only 30 feet it would be annoying to have three sections and two scarfs.  If that's the only option, then so be it.  

thanks for the input
JP

[Jim_Rogers]

What you have labeled as an end girt is truly a tie beam.
A tie beam is a member that usually is in tension, that is holding the two walls from spreading out from the roof load pushing the plates outward.
Your frame design with two queens supported by the tie and the posts under the tie will greatly reduce the "thrust" of the rafters on the plates and thus the tie beam tension.
So, you may not need a "tension scarf". But that is truly an engineering question. 
Whichever type of scarf you decide on it should be supported by one of the four braces you show in that bent.
Good luck with your project.
Jim Rogers

[timberframe]

I've been in situations like yours before and agonized over the solution, but sometimes it's best just to crack open the wallet and order timbers from somewhere that can supply full length.  The added cost to a building that size will be pretty small when you look back on it and it gives you a lot less to worry about.  Alternatively you could put a simple splice over a post and incorporate steel somewhere hidden to help with tension,if the tie is going to be loaded with second floor loads as well you could put a bolster block on the post too.  If the tie is only in tension and not used to carry a second floor load, putting a scarf over a post wouldn't  be the end of the world, but you'd still need a scarf that works in tension (none are great!) and be able to execute it very well.

[Jpd]

Thanks Guys
I will try and find a local mill that can saw 30 feet, I agree that makes sense.  There will be a second floor, but I'd like to avoid steel as much as practicable.

In the event I need to use the 21 foot beams, Is there any thought on having scarf joints too close to the ends, say over the two braces outboard of the two center posts?

thanks
JP