CENTERCORE STRENGTHENING SYSTEM FOR SEISMIC HAZARD REDUCTION OF UNREINFORCED MASONRY BEARING WALL BUILDINGS

The CenterCore technique of reinforcing unreinforced masonry walls was developed with the help of a National Science Foundation grant in 1984. The CenterCore strengthening system consists of a reinforced grouted core placed in the center of an existing unreinforced masonry wall. The core is provided by coring a vertical hole from the top continuously through the wall into the existing footing. The drilling is a dry process with debris removal handled by a vacuum and filter system that controls the debris collection and keeps the dust to a minimum. Reinforcing steel is placed in the center of the hole, usually a #6 to #9 bar, and a polyester-sand grout is placed to bond the assembly. The migration and strong bonding of the grout to the inner and outer wythes of brick provides a 'homogeneous' structural element to resist both in-plane shear and out-of-plane bending.