In June, SDCI conducted two public webinars on the draft Unreinforced Masonry (URM) Retrofit Technical Standard. This document is the first step in establishing minimum seismic standards for the earthquake retrofit of Seattle’s 1,100 vintage brick buildings which are prone to collapse in an earthquake due to lack of structural reinforcements. The draft URM Retrofit Technical Standard will inform the future mandatory retrofit ordinance. Be sure to check out the slides and recordings from these presentations.
To support building owners that are eager to begin the retrofit process, SDCI is moving forward with adopting components of the draft URM Retrofit Technical Standard with Director’s Rule 6-2023, Alternate Method for the Seismic Improvement of Unreinforced Masonry Buildings (URMs). The draft Director’s Rule is available now for public comment.
The intent of this Director’s Rule is to provide a voluntary methodology for seismic improvements to URMs which addresses testing and quality of existing masonry construction and mitigates collapse hazards in an earthquake. This rule will formally allow use of the Alternate Method for retrofit, resulting in a minimally acceptable level of safety from collapse through the installation of wall anchors, wall bracing, and parapet bracing. A building must meet certain criteria in order to qualify for this method.
The Alternate Method was developed to provide building owners a seismic retrofit option with reduced costs compared to a code-based retrofit while increasing the life safety of the building. Building owners should consult a structural engineer to determine their preference for building performance in an earthquake and design their retrofit accordingly.
The development of a URM retrofit standard was initiated by the 2021 passing of Joint Resolution 32033 which declared the intent of City Council and the Mayor to establish a mandatory retrofit program, an effort spearheaded by the Alliance for Safety, Affordability, and Preservation (ASAP!) and Seattle City Council Member Lisa Herbold.
Image showing bracing of URM wall. Source: MKA
Image showing braced parapets. Source: SSF Engineers
Image showing bolting to prevent out-of-plane movement. Source: Lund Opsahl