Reinforce Existing Steel Roof Diaphragm At New Opening

Using 5 8 inch puddle welds for attaching deck to supports and 10 sidelap screws we find the nominal shear strength in the table for 0 0295 inch thick wr deck is 0 740 klf using a 36 4 12 inch o c support fastener.

Reinforce existing steel roof diaphragm at new opening.

The corresponding diaphragm chord forces are therefore equal to m divided by the diaphragm depth b. In buildings with wood diaphragms and reinforced concrete or masonry walls the most common chord members are reinforcing steel placed in the wall at or near the roof diaphragm elevation and a structural steel angle bolted to the wall. Apply construction adhesive along the edge of the truss to strengthen the connection to the plywood roof deck. The maximum roof diaphragm moment m equals ww wl x l2 8.

Stiffen trusses by joining them with 2x4s running from one end of the house to the other. A concrete floor is relatively rigid compared to steel moment frames whereas a metal deck roof is relatively flexible compared to concrete or masonry walls. 2 the original structural design assumptions e g. The maximum unit shear on the wall diaphragm is also equal to the roof reaction r divided by b.

The proposed opening may affect existing floor structures in one or all of the following ways. It includes information for the design of steel deck diaphragms for roof and floor decks and complies with the requirements of the ansi aisi s310 2013 north american standard for the design of profiled steel diaphragm panels. Importance is the in plane rigidity of the diaphragm relative to the walls or frame elements that transmit the lateral forces to the ground figure 4 29. Wood diaphragms are generally.

September 2015 the fourth edition of the sdi diaphragm design manual ddm04 replaces the third edition ddm03. Put on the adhesive as you would caulk. Once the opening is located relevant existing floor structures must be carefully assessed. Where the existing chord member is adequate rehabilitation may be limited to enhancing shear transfer.

1 the design live load is increased at the new stair landing area thereby overloading adjacent portions of the floor.