By James S. Lai, S.E., F. SEAOC, Life F. ASCE, Chair SEAOC Wind Committee
Status of Wind Code Development
ASCE 7 Wind Provisions: During the current cycle of the ASCE 7 Standard development, several members of the SEAOC Wind Committee and its Solar PV System Subcommittee participated and helped to facilitate proposals that originated from SEAOC. Result of these efforts will be included in ASCE 7-16 and has been summarized in 2015 SEAOC Convention paper by Lai and Maffei “Advancement in Wind Design.” The topics include:
- Gravity load requirements related to rooftop solar arrays
- Seismic design requirements for rooftop solar arrays, including unattached arrays
- Wind load requirements for low-profile solar arrays on flat roof systems
- Wind load requirements for solar arrays parallel to roof surface
- Cladding wind loads on buildings with irregular plan shapes
- Clarification of risk category for rooftop equipment or appurtenances
iCode Wind Provisions: While Wind Committee did not originate code change proposals, the Committee acted to review change proposals related to wind in IBC and IEBC prior to the 2016 ICC Code Change Hearing (CCH). Our suggested recommendations were passed on to SEAOC delegate Steve Kerr. We supported the inclusion of the wind maps in IBC; and we leaned towards having the Alternate All Height Method to remain in IBC, which gives conservative and handy guide on pressure coefficient for components and cladding. The Committee will continue its involvement in reviewing public comments prior to the Final Action Hearing.
Activity since last report
The Committee discussed the Special Wind Regions shown on ASCE 7 wind maps applicable to certain areas within California. As reported previously, the Committee engaged, as part of the committee activities, the wind engineering company, Cermak Peterka Petersen (CPP) of Fort Collins, CO, to perform a pilot study of portions of Southern California in order to gain knowledge of extent of extreme wind speeds in select regions. The study included parts of Coachella Valley. The data showed wind speed shown on ASCE 7-16 maps may be used without increase even though the study area is within the special wind region. The study also included the region along Highway 241 to the northeast of Irvine, which is not currently within the special wind region. The data in this area showed the ASCE 7-10 wind speeds would be more appropriate than those shown in the ASCE 7-16 wind maps. The Committee will prepare a more detail recommendation to address design wind speeds in Southern California.
Solar PV Sub-Committee
The subcommittee met last September at Indian Wells. Four task groups have been assigned to focus on: a). Testing of solar array components to determine design strength; b). Gravity load design and code requirements for roofs to support PV arrays; c). review of streamlined permitting for residential PV arrays; d). Further work on Wind design of PV arrays. Subcommittee will continue on development of design criteria, commentary and guidelines for solar PV systems, and updates to SEAOC PV-1 and PV-2 publications in conjunction with the release of ASCE 7-16.
The Committee plans to start on a wind design examples to include work examples based on ASCE 7-16 including topics on the design of solar PV systems and specific topics which are commonly overlooked by engineers. The Wind Committee normally meets one time at the Convention site and holds three quarterly video-conference meetings. We have eight voting members; and, in addition, one or more alternates are also appointed from each Member Organization. The Solar PV Committee has 12 voting members and well over 25 associate members and observers. As a rule, we welcome SEAOC members to participate as an observers to contribute in meetings.