SEISMIC PERFORMANCE OF CONFINED SILL PLATE CONNECTIONS

In the aftermath of the 1994 Northridge earthquake, extensive field in vestigations revealed damage in wood frame construction in the form of splitting of the 2 x 4 or 2 x 6 wood sill plates along the line of an chor bolts that typically connect shear walls to the masonry or concre te foundation. Due to the severity of such brittle failures, the city of Los Angeles has recently restricted the use of 2X dimension lumber in sill plates and requires the use of 3X dimension lumber. This paper presents an experimental investigation of the performance of 2X dimen sion lumber sill plate connections at the yield and ultimate Limit sta tes during incremental quasi-static reversed cyclic loading and sugges ts possible cost-effective retrofit strategies for their improved seis mic performance without having to increase the sill plate thickness. P roposed retrofit strategies are based on providing confinement to the sill plate using metal reinforcing straps and reinforcing clamps to in crease the deformation capability and energy dissipation capacity of t he connection, while maintaining substantial levels of connection stre ngths.