Racking Shear Tests
Racking Shear Tests
(OP)
Just getting into stud walls and shear walls and have a question regarding racking shear testing - specifically ASTM E72 and ICC AC04. ASTM E72 requires that the sheathing be held off the base to allow for free rotation under racking load. This makes sense since sheathing is installed onto the stud wall and may not always be flush with the base of the sill plate and could act independently. However, ICC AC04 is specifically made for composite sandwich panels (SIPs) and still requires the panels be raised 3/4'' off the test frame to allow for free rotation. Since these are factory manufactured composite panels that are set onto a slab, shouldn't the slab be able to help with the racking load? The SIPs would be sitting on the slab in an actual application and not elevated off the slab. Why should the resistance to the racking load be penalized in the test?






RE: Racking Shear Tests
In any case, the slab or wood floor does not "help with the racking load", it supports the racking load only after any gaps between the sheathing and slab or floor are taken up. The shear (racking load) is resisted by sheathing on a stud wall or composite action between the plies of a SIP wall. I think its reasonable that in either case the sheathing of a stud wall or outer ply of a SIP wall may not be in 100% contact with the base.
(Actually, in the case of an exterior shear wall, the sheathing may extend beyond the floor and never make contact with the floor)
RE: Racking Shear Tests
RE: Racking Shear Tests