Bond Beam
A bond beam is a horizontally reinforced element in a masonry wall that provides resistance to shear loads and also helps distribute lateral loads throughout the wall section. Reinforcement is placed in special bond-beam units that have reduced-height cross webs and grouted solid. Bond beams are typically one course tall; grout is prevented from filling cells below by placing a mesh-type grout stop material in the bed joint underneath the bond beam. Bond beams are usually seen at the top of foundation walls, tops of walls, and at each floor diaphragm connection. Intermediate bond beams are often required in higher seismic design categories.
Structural Considerations
Bond beams are sometimes arbitrarily placed in walls as a stiffening or tie element, and are recommended at tops of walls, floor connections, and top of foundation walls. Intermediate bond beams are normally not necessary unless required to resist shear stresses or to fulfill minimum seismic reinforcement requirements.
Construction Concerns
The intersection of a bond beam with vertically reinforced cells can be very congested, with multiple bars in each direction. Minimize the amount of bond beam steel to improve grout flow and permit proper grout consolidation.
Use L-shaped corner bars, lapped with the bond beam steel, to provide continuity around building corners.
What to Do at Expansion and Control Joints
For most conditions it is best to cut bond beam reinforcement at expansion joints and control joints. The exception to this rule is at floor diaphragms, where the bond beam may be acting as the diaphragm chord and must be continuous down the wall. It is possible to detail a slip connection around bond beam reinforcement, but normally, lateral continuity across movement joints is not required for structural performance.
