Without seeing it, you could try drilling holes through the 2 joining joists then place some bolts in with large washers and try to draw them together by tightening up the bolts. You may have to reinforce the joists where they are attached to the header joists with some steel brackets so they don't pull away.
Also try to determine why the joists are pulling away from each other....could be some posts are settling or one or the other of the sections is not level and leaning away.
Have fun.
------------------
Bart Blainey, B.E.R.
Consultant/Journeyman Carpenter
Building Envelope Specialist
Master Renovator
provip@prodeck.org
http://www.prodeck.org
Barton Blainey (provip) specifically assumes no legal liability or responsibility for the accuracy, completeness or usefulness of any information or process disclosed. The above further expressly advises that any use of or reliance upon the information and or opinion disclosed is at your risk .
_________________________
Bart Blainey, B.E.R.
Consultant/Journeyman Carpenter
Building Envelope Specialist
Master Renovator
provip@prodeck.org
http://www.prodeck.orgBarton Blainey (provip) specifically assumes no legal liability or responsibility for the accuracy, completeness or usefulness of any information or process disclosed. The above further expressly advises that any use of or reliance upon the information and or opinion disclosed is at your risk .