When possible, laterally brace interior concrete masonry partitions along the top of the wall. It is usually impractical or uneconomical to brace the wall with columns, piers, or pilasters, especially when the walls are built after the building has been occupied.

Chapter 5 of the Specifications for Masonry Structures (ACI 530.1/ASCE 6-05/ TMS 602-05) allows interior non-bearing concrete masonry partition walls to be constructed to a height 36 times their thickness without any additional reinforcement. Interior partition walls can span twice the height of exterior masonry walls due to the lack of wind loads.

Steel joists can deflect as much as 2 in. at the center point when live loads are applied. When bracing the concrete masonry partition wall to the bottom of the steel joist, a clearance space must be maintained between the top of the wall and bottom chord of the joist to accommodate this movement.

In cases where joists are spanning perpendicular to the partition wall, a clip angle should be welded to the bottom chord of each joist. The top course of the partition should be constructed of two wythes of masonry. Each wythe should be built tight to the vertical leg of the bracing angle and bonded with a partial collar joint. The vertical leg of the angle performs as a shear key, engaging the slot between the two wythes of masonry and holding the wall in place.

This connection braces the wall at the bottom chord of the joist. If the roof deflects under live loads, the vertical leg of the angle slips down the open collar joint while holding the wall in place. The clearance between the bottom chord of the joist and the top of the masonry wall accommodates this movement, preventing crimping of the joist due to the masonry abutting the bottom chord.

This type of connection should be used where fire ratings are not a consideration and when the joists are experiencing maximum deflection.

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.