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6. Diaphragm Strengthening
Most of the seismic load on the retrofitted URM structure will be resisted by the wood diaphragms. It may be necessary to strengthen the diaphragm with additional fastening or replacement of the diaphragm sheathing.
The lateral diaphragm forces need to be transferred into the walls. Often, the attachment of the blocking or rim joist to the walls is inadequate or missing. New shear anchors can be installed to transfer the horizontal diaphragm forces into the walls.
