Some designs require that sloped open web joist roof systems be laterally braced to a concrete masonry fire wall. When non-bearing masonry walls need to be braced by steel joists that are sloped, prefabricated metal weld plates should be embedded into the masonry walls. The concrete masonry cell directly behind the welding plate should be solidly filled with mortar or grout.
Weld plates, such as those manufactured by Trico Masonry Products, must be installed to align with the steel joists. The metal weld plates should be fabricated and delivered to the jobsite prior to the beginning of construction. The weld plates can be adjusted easily, assuring correct installation.
Lateral bracing of the wall can be achieved by extending the horizontal bridging angles and welding them to the welding plates secured to the wall. The extended angle should be aligned with the horizontal bridging to prevent crimping in the joist chords due to pressure induced by wind loads.
Extending the horizontal bridging and connecting it to the masonry wall permit lateral loads to be transferred into the roof diaphragm, which braces the wall against wind loads. This arrangement eliminates the need for columns, piers, pilasters, or cross walls for lateral bracing if the wall is designed and constructed within height limitations allowed by code.
If spacing of the steel joist is greater than 6 ft, bridging alone may not be adequate to transfer wind loads into the roofing system. The concrete masonry might be required to be reinforced with vertical rebar and grout to provide additional lateral support.
Additional information on this general subject is available in the “Masonry and Steel Detailing Handbook” authored by Walter A. Laska. The price for the 218-page book is $51, and it can be ordered atwww.wocbookstore.com.