URM Building Retrofit Applications
Explore Retrofit Applications
Wall to Roof or Floor Anchorage
The URM walls must be tied to the horizontal diaphragms (roof and floors) to increase their capacity for out-of-plane loading and reduce the risk of catastrophic failure. There are many ways to anchor the walls to the diaphragms. Through-bolting with large bearing plates on the exterior, combined with epoxy adhesive in the URM wall wythes will provide tensile and shear resistance for the wall anchor and is one possible solution. One caveat in determining the optimal location for these anchors is usually dependent on the fact that many URM buildings utilize beam pockets to support the joists. The wall anchor will perform better when it is away from the beam pocket. When deciding on the anchor location, the midpoint between framing is more ideal, but requires additional framing elements to attach to the joists.
Simpson Strong-Tie Products for Wall to Roof or Floor Anchorage
AT-XP® is a fast-cure, all-weather, high-strength anchoring adhesive and may be used to anchor threaded steel rods or deformed steel reinforcing bars in unreinforced masonry.
AT-XP High-Strength Adhesive
SET-XP® is a high-strength anchoring adhesive and may be used to anchor threaded steel rods or deformed steel reinforcing bars in unreinforced masonry.
SET-XP High-Strength Epoxy Adhesive
Screen tubes are used in hollow base material applications to contain adhesive around the anchor and prevent it from running into voids.
Steel Adhesive-Anchoring Screen Tubes
Holdowns are often used to resist out of plane forces, tying the wall to the roof or floor assembly. The HTT5-3/4 holdown uses a 3/4" diameter anchor bolt, which is typically required when anchoring into URM.
Holdowns
In retrofit applications, joist hangers might be used to support added blocking or might be installed horizontally to help resist out of plane anchorage forces in addition to their typical download and uplift load applications.
Joist Hangers
Retrofit and bearing plates are often used in out of plane wall to roof or wall to floor anchorage conditions and utilize a larger bearing surface on the side of an unreinforced masonry wall.
Retrofit and Bearing Plates
Straps may be used to resist out of plane wall to roof or wall to floor anchorage forces or drag forces when installed on the top or bottom of roof or floor framing. One out of plane force-resisting solution uses the MSTD Marriage Strap, an overlapping in-line splice between an HTT tension tie and a CMSTC16 coiled strap.
Straps
Angles transfer shear forces for wood to wood framing connections. The A35 with 1/2" long screws might be used to transfer shear forces from 1/2" minimum thickness sheathing to wood framing connections.
Angles
Hand-drive or collated screws may be used to enhance wood diaphragm strength. Strong-Drive structural wood screws may be used for connector or steel to wood connections.
Screws
Hand-Drive or collated nails may be used to enhance wood diaphragm shear strength or for wood to wood or steel to wood connections.
Nails