Use of Injection Grouting/Grouted Metal Ties to Improve Seismic Retrofitting ofUnreinforced Masonry (URM) Buildings

摘要

Improved performance from seismic retrofitting of unreinforced masonry (URM)buildings has been well documented. A study conducted after the 1987 Whittier Narrows, California earthquake found that complete retrofitting of URM buildings in accordance with established criteria significantly reduces earthquake damage at moderate ground motions (Bruce 1993). That study examined a database of 113 structures, 81 of which had been completely retrofitted in accordance with the Los Angeles Building Code (Division 88), the San Francisco Building Code (section 1O4f) or other applicable codes. The other 32 had been partially or arbitrarily retrofitted with no known criteria. The study also concluded that arbitrary or incomplete retrofitting did not significantly improve performance under moderate ground motions nor improve life safety under large ground motions. The purpose of this report was to introduce a project that intended to improve current retrofitting techniques prescribed in the City of Los Angeles Building Code, Division 88. As per the objectives set forth in Chapter 1, the Northridge earthquake was discussed to provide a background on the event which led to the inception of this project. Current retrofitting technologies and those prescribed by Division 88 were also reviewed. (MM).