By David Ojala, Past Chair (SEAONC) and Wayne Brown, Chair (SEAOSD)
SEAOC’s member organizations each have an active Existing Buildings Committee, whose role it is to keep abreast of local policy developments (and work to guide their development), hear challenges faced by local practitioners, and help educate their members on the nuances of working with our diverse stock of existing buildings. The primary role of the SEAOC EBC has been to be a forum for representatives of those local EBCs to share news, local developments, and lessons learned to their peers across the state.
The two big issues influencing our committee this year have been ongoing mandatory soft-story/weak-story/open-front (SWOF) wood-framed buildings retrofit programs in Northern California, and the development of SWOF and non-ductile concrete (NDC) ordinances in Southern California. San Francisco is also in the early stages of developing its own NDC ordinance, not to be outdone by the Los Angeles. San Diego is also looking into an SWOF ordinance. To this end, the SEAOC EBC has been reviewing and discussing work done by the SEAOSC EBC and Seismology Committee in developing SWOF and NDC Design Guides for the use of local structural engineers. These guides provide a general review of the state-of-the-art in research and practice for seismic evaluation and retrofit design, provide some guidance on meeting the specific provisions of the local ordinances, and present example retrofit design solutions. While currently targeted for Southern California, it is anticipated that the general information and format can be adapted to other jurisdictions pursuing NDC retrofit programs of their own.
On the soft-story front, one of the most obvious choices of lateral system for use in remediating a SWOF condition is the steel moment-resisting frame. However, engineers across the state have had difficulty applying the typical conservative methods they would normally use to provide stability bracing to these frames in a steel/concrete structure in a typical wood-frame retrofit. This has led to questions and debate about the best way to apply the AISC stability bracing provisions in a SWOF retrofit situation or even the extent to which the requirements must be met given the often limited non-ductile performance and gravity capacity required of these frames in typical retrofit applications. SEAOC EBC has decided to take the lead on investigating this situation and has supported a pair of papers on the subject, which were presented at the SEAOC Convention in Maui. It is anticipated that, after further research and review, the papers will serve as the basis for a SEAOC white paper on the topic in the coming year.
The SEAOSD EBC has also been working with their local building departments to encourage acceptance of ASCE 41 and to prepare them for reviewing ASCE 41 retrofit submissions, including developing consistent protocols for structural peer review committees. The SEAOCC EBC has also been monitoring the growing adoption of the Permit Simplicity program (originally developed in Phoenix) throughout Sacramento County. The program is intended to provide streamlined plan and permit approval for small improvement projects, but is being looked at for application to new building construction. SEAOCC EBC will be reviewing the program to make sure that the procedures match IBC requirements and maintain a level of care consistent with the complexity of the structures being reviewed.
In addition to these major regional topics of discussion the committee has also met to discuss several relevant IEBC code change proposals submitted to the ICC this past fall (including one major proposal overhauling IEBC Appendix A1 on unreinforced masonry retrofits developed by an ad-hoc subcommittee) and is continuing to monitor their progress through the approval process. We have been monitoring the progress of two other SEAOC committees related to existing buildings: the Exterior Elevated Elements (EEE) committee, formed to discuss inspection of existing and construction of new balconies and other similar elements in buildings, and the Earthquake Performance Ratings System (EPRS) committee, formed to review the SEAONC EPRS and provide recommendations to the SEAOC board regarding its possible adoption or modification by SEAOC. The committee has also been providing support (in the form of peer reviewers) to the ATC-124 Project, which is developing a guide and example problems for the use of ASCE 41, and provided review and comments on a SEAOC Communications Committee document on concrete tilt-up construction.
The committee also provided suggestions to the state Buildings Standards Commission on the implementation of the CEBC for the coming year. There will be some additional work on this topic as we are discussing maintaining the commentary for the previous chapter 34 to the IEBC and provide suggestions for errata to be published.
With local policy development activities set to continue at an equally aggressive pace in the coming year and SEAOC EBC delegates set to remain busy guiding these efforts, the SEAOC EBC looks to continue under new chair, Wayne Brown, as a source of consistency and guidance so that engineers can both serve and adapt to the unique needs of their communities, while speaking with a consistent voice.