August President's Message
Thursday, August 1, 2019
Posted by: Janiele Maffei
My husband and I felt the July 4th 6.4 earthquake on the 15th floor of a 19-story building in Sacramento. We both knew it was a large, distant earthquake and shuddered at what it could do to older construction in any of the dense urban environments around the State. Within minutes, however, the epicenter was confirmed in the sparsely populated Mojave Desert near Ridgecrest (population 27,000), Trona (population 1,900), and the Naval Air Weapons Station, China Lake. I was already making plans to visit the affected area when the M7.1 earthquake occurred the following evening.
While the remote location of the Searles Valley earthquake series reduced the number of people and buildings affected, it provided important lessons on what to expect should one or more damaging earthquakes have a direct hit on a major metropolitan region in California. A special session on this earthquake series has been added to the SEAOC annual convention and I invite all attendees to participate.
As we reflect on the lessons learned in recent earthquakes, we can be proud of the activities of two SEAONC committees that have a direct impact on the seismic resiliency of California: The SEAONC Seismology Committee recently contributed to the renewal and expansion of the SEAOC Blue Book, SEAOC’s Seismic Design Recommendations Manual. This document served for decades as the signature SEAOC interpretation of the seismic provisions of the Uniform Building Code (UBC). The seismology committee also reviewed and voted on the BSSC PUC ballot proposals; reviewed and provided input on San Francisco DBI’s AB082 and AB083; and supported the efforts of active subcommittees, including the Concrete Cubcommittee and Light Frame / Wood Subcommittee.
The SEAONC Existing Building Committee (EBC) helped the City of San Francisco complete an inventory of all of the concrete buildings in the city with a considerable amount of data including number of stories, occupancy, square footage, etc. with the idea of understanding the pre-1980 inventory for use in a potential non-ductile concrete ordinance.
With the above information committee members performed a FEMA P-58 analysis on the inventory to assess the potential loss and to help provide information on relative risks. They also did a more focused study on archetype buildings typical of the inventory to better understand the risk of certain building types and also to assess ATC 78 and compare it to ASCE 41. EBC has two papers and presentations at the upcoming convention that provides a detailed description of all of the above. One paper focuses on the inventory and the other on the analyses.
Thank you to the dedicated members of these committees. I hope to see many of you at the SEAOC convention in Squaw Valley this August.