Evaluation of seismic performance of anchored brick veneer walls

This paper reports the first part of an ongoing research project that is looking into the seismic performance of veneer walls. The type of veneer of interest for this work is normally anchored to the backup wall through metal ties. Brick veneer walls are supported in most cases by shelf angles attached to the floor slab at each story and are supposed to carry only their own weight and not participate in in-plane lateral load resistance. To achieve this behavior, horizontal and vertical movement joints are necessary. Ideally, this design could isolate the lateral movement of the backup wall from that of the veneer wall, thus preventing any distress to the veneer. However, earthquake reconnaissance reports show many failures of veneer walls with the potential of life-safety hazard. In this paper, it is discussed how the vertical differential movement between the brick veneer and the frame can close the gap between the underside of the shelf angle and the top course of brick, thus putting the brick veneer under high compressive stresses. It is shown that this can result in proportionally high friction forces during earthquakes with the possibility of shear cracking of the veneer before sliding between the brick veneer and the supporting steel shelf angle occurs.