Friday, December 9, 2011

Jacking System Detailing

I am designing a shoring and jacking system for a damaged heavy timber truss. The truss is a WWII vintage multi-ply truss with split ring connections, etc. As is often the case with such trusses, the subject is suffering from a tension chord rupture. One of the two bottom chord plies has completely ruptured, and hence the remaining bottom chord ply and its split ring connections have assumed the full tension load.

In order to repair the damage, the first step is to support and minimally raise the truss to relieve the presently overstressed members and connections. My intent is to design a structural steel frame to pick up the truss at the structurally appropriate locations, and use bottle jacks supported from shoring platforms to gently raise the frame. I am comfortable with the design of the shoring platforms; however, I would like to know of any references that might be helpful in detailing the support assembly consisting of the bottle jacks and steel frame. My primary concern is stability at the bearings of the steel frame on the jacks.

Thanks in advance for your assistance,

Brian Felker, P.E.
Design Manager/Structural Engineer
9742 Maryland Ave, Bldg Z-140
Norfolk, VA 23511-3095
(p) 757.341.2047
(f) 757.341.2095