When masonry walls are constructed independent of the steel structure, anchorage of the masonry to the steel column is not required if the walls span vertically and are supported laterally by floors and roofs acting as diaphragms or structural members. However, if walls span horizontally, the concrete masonry must be anchored to the column to brace the wall laterally.
Distribution of the wind load acting on the wall is resisted by both wythes in proportion to their relative thickness. Joint reinforcement ties the brick wythe to the concrete masonry, which creates a positive bond. Wind loads are transferred from the brick wythe to the concrete masonry wythe and through the anchors to the steel column. This connection laterally braces the masonry wall to the steel column.
Use an adjustable anchor connection if a non-rigid connection between the masonry and the column is required. One type of adjustable anchor engages deformed rods welded to the column flanges at locations where the masonry wall completely bypasses the steel column and the column web is parallel to the wall. Deformed anchors can be supplied in continuous sections if spacing requirements are tight. This type of connection permits in-plane movement of the wall and laterally braces the masonry to the steel column.
Consider pull out strengths and resistance to buckling under load when selecting anchor types. Providing two anchors increases load capacity and increases vertical spacing requirements.
Joint reinforcement is supplied in 10-ft sections. To maintain a continuous bond of masonry wythes, the ends of the sections should be lapped (or bypass each other) by a minimum of 6 in. Do not permit joint reinforcement to overlap anchors, which creates an inadequate bond between the anchor and column. Joint reinforcement should be clipped where intersections with the anchor occur, or when possible, the joint reinforcement and anchors should be set in alternating concrete masonry courses.
The space between the concrete masonry and steel column should be kept clear of mortar bridging. If the column and masonry are bonded tightly, any movement of the column can be transferred into the masonry, causing cracks to develop.
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.