In this article, Fred Turner provides an update on one of the many ongoing activities of the SEAOC Existing Buildings Committee.
In the late 1980’s and early 1990’s, SEAOC’s Existing Buildings Committee developed its first statewide consensus on retrofit provisions for unreinforced masonry (URM) buildings, later editions of which you can find in the California Existing Building Code. These provisions were developed before performance based engineering. They are expected to significantly reduce the risks to life from vulnerable URM buildings. Performance in damaging earthquakes has been mixed, but generally these retrofits have met or exceeded expectations.
In California, some 11,000 URM buildings have been retrofitted using various versions of these provisions. Hundreds of other building retrofits in Washington, Oregon, Nevada, Utah, Canada and New Zealand have also benefited.
Since the early 1990’s, several other versions of these provisions were also in use including guidelines in Canada and ASCE 31 that was replaced by ASCE 41’s Chapter 15 in 2013. Since different volunteer committees had revised these versions over the years, there is now a proliferation of somewhat inconsistent approaches. But they are all largely based on SEAOSC’s and later SEAOC’s code development efforts as well as earlier research and testing by Agbabian, Barnes, Kariotis and others.
In March 2015, an ad hoc Task Force was formed by the SEAOC Existing Buildings Committee to try to reduce this proliferation and coordinate a code change proposal to amend and update the unreinforced masonry building retrofit provisions in the International Existing Building Code Appendix Chapter A1 with proposed changes to Chapter 15 of ASCE 41 Seismic Retrofit and Evaluation of Existing Buildings.
James Lai and Nels Roselund from SEAOSC, Bill Tremayne and Diedra Dawson from SEAONC, Joyce Fuss and Fred Turner from SEAOCC, and Jim Miller from SEAOSD, were joined by Wade Younie from SEAO and Terry Lundeen from SEAW to participate in this six-month effort. The result is a code change proposal that was refined by the SEAOC Existing Buildings Committee and submitted to ICC.
SEAOC’s IEBC-A1 code change proposal will be considered at ICC’s Louisville Kentucky hearings on April 17 – 27th. If successful, it will be included in the 2018 edition. The ASCE 41 Committee will complete its second ballot on March 13th and if the ASCE 41 Masonry Team’s proposal to change Chapter 15 is successful, the proposal will be included in a ballot slated for public comment in the 4th quarter of 2016 to create ASCE 41’s 2017 edition. If SEAOC members would like to obtain copies of the proposals, please contact your local Existing Buildings Committee Chair.