P17 SDC* Working Group Meeting 2 *Seismic Design Category W.G. P17 SDC* Working Group Meeting 2 *Seismic Design Category Julie C. Furr, PE, SECB Senior Engineer CSA Engineering, Inc. Chair P17 SDC Working Group

Outline Welcome Related Groups – Topic Summary W.G. Outline Welcome Related Groups – Topic Summary P17 SDC Fundamental Task – Review Revise SDC Definition? Redefine SDC Parameters? Open Discussion

Schedule Project 17 to be Complete December 31, 2017 W.G. Next Meeting: November 29, 2016 3 Meetings in 2017 SDC Working Group Initial Meeting: August 10, 2016 Meeting 2: November 4, 2016 Meeting 3: December 2017 (proposed) Does the group prefer multiple short meetings or a face to face meeting before november? Expenses, productivity?

Related Groups – Topic Summary W.G. Related Groups – Topic Summary PUC IT-01 (Pekelnicky) Seismic Performance Structures Non-Structures Map fluctuations Accuracy and Precision Working Group (Dolan) Accuracy of mapped values and fluctuations Precision of reporting Very broadly stated, P17 has discussed the issues… So, we’re looking at the other side of the equation…

P17 SDC Fundamental Task-Review W.G. P17 SDC Fundamental Task-Review P17 Discussions Issues: Mapped ground motions fluctuate too much and reported accuracy on USGS web tool is misleading. Solutions? Can engineering community disregard USGS changes within a predefined margin (stated margin of error)? Can ground motion fluctuations be flattened in some way? Round off reported accelerations to predefined accuracy? Most proposed solutions directed to the science and reporting of mapped values. Working Group Creation Alternate approach: Hold discussions to change how seismic design categories are designated. Proposed approach directed to the engineering application without constraining the science. Very broadly stated, P17 has discussed the issues… So, we’re looking at the other side of the equation…

P17 SDC Fundamental Task-Review W.G. P17 SDC Fundamental Task-Review Initial Task Highlights… Define how Seismic Design Categories are decoupled from ground accelerations. Broadly consider impacts on material standards and practical implementation. What SDC boundary/definition would be most palatable (and therefore sellable) to adopting and enforcing jurisdictions? Currently based on Sds/Sd1 as listed in Tables 11.6-1 and 11.6-2 in ASCE 7 Material standards: if we develop a perfect solution but it upends the ACI provisions, do we really want to go there? Politics: we can develop a perfect solution to address science and engineering, but useless if governing jurisdictions amend standards to change=> latest AR amendment

P17 SDC Fundamental Task-Review Meeting 2 W.G. P17 SDC Fundamental Task-Review Meeting 2 P17 Discussions Issues: Mapped ground motions fluctuate too much and reported accuracy on USGS web tool is misleading. Detailing requirements across the board are based on SDC. Very broadly stated, P17 has discussed the issues… So, we’re looking at the other side of the equation…

P17 SDC Fundamental Task-Review Meeting 2 W.G. P17 SDC Fundamental Task-Review Meeting 2 Revise SDC Definition? Fundamentally based on ground motion intensity correlated to PGA and PGV Alternate means of defining hazard? General Correlation MMI V SDC A - No real damage MMI VI SDC B - Light nonstructural damage MMI VII SDC C - Hazardous nonstructural damage MMI VIII SDC D - Hazardous damage to susceptible structures MMI IX SDC E - Hazardous damage to robust structures Very broadly stated, P17 has discussed the issues… So, we’re looking at the other side of the equation…

P17 SDC Fundamental Task-Review Meeting 2 W.G. P17 SDC Fundamental Task-Review Meeting 2 Redefine SDC Parameters? SDC is currently determined based on site class, building occupancy and importance, and MCE accelerations. Actual ground motion will vary only with site class. Building occupancy and importance has no impact on ground motion. Very broadly stated, P17 has discussed the issues… So, we’re looking at the other side of the equation…

W.G. Open Discussion SDC’s must be defined in a way that will facilitate use and encourage adoption of codes without significantly increasing code complexity or fanning jurisdiction resentment already in existence, while still maintaining life safety. have sugg approaches already emailed in but wanted to get your ideas without influence first. Will send them out with meeting summary