WEBVTT

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Hello everyone. So welcome to today's
webinar.

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My name is Jiqiu Yuan.

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I am the Executive Director for the
Multi-Hazard Mitigation Council.

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Also the Building Seismic Safety Council
at the National Institute of Building

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Sciences, known as NIBS.

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NIBS was established by the US Congress
to ensure that all the areas of the built

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environment work together to utilize the
best technology and focus on the

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sustainable sustainability when creating
the place where we live, work, learn and

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play. So developing research and
convening experts to solve problems is a

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part of our overall mission.

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The Building Seismic Safety Council,
known as the BSSC, is a council within

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NIBS established in 1979.

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The council's purpose is to enhance the
public safety by providing a national

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forum that fosters improved seismic
planning, design, construction and

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regulation in the building.

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Community. Community. Community.

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We are proud to work with all our federal
and industry partners over the past 40

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years to help advance the seismic safety
of our nation.

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Especially, we want to thank our sponsor,
FEMA, the Federal Emergency Management

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Agency, for their support for producing
the NEHRP, recommended seismic provisions

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for the past many years and also to
develop the supporting document,

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including today's webinar.

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So today the webinar is our ninth webinar
in our NEHRP webinar series for this

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year. This webinar series is based on the
2020 NEHRP, NEHRP Design Example

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publication. So all these slides have
been published by FEMA is in the public

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publication number called FEMA P-2192.

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Again that's FEMA P-2192.

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Strongly encourage you guys to download
the report, which has more detailed step

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to step design examples.

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Also the PowerPoint PowerPoint slides.

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So our early ones in this series, we have
covered many code change proposals that

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were introduced by the 2020 NEHRP
provisions like the diaphragm design,

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coupled shear walls the new construction
component design, etc.

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So if you missed them, you can listen to
the recording through the BSSC website.

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So today we have three renowned speakers
to talk about the grand motion topics,

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the multi-period response vector, the new
seismic design values under the new

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requirements that are adopt in the ASCE
7-22 and hopefully will answer all the

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grand motion questions you may have.

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Again, we have the most knowledgeable
experts with us today.

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With that is my great pleasure to
introduce our three speakers.

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So our first speaker is Charlie Kircher.

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And Charlie is a National Academy of
Engineers member, registered a

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professional engineer with more than 40
years of experience in earthquake

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engineering, focused on the vulnerability
assessment, risk analysis and innovative

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design solutions.

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Dr. Carter is active in seismic code
development committees of SEAOC also the

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ASCE, also the Building Seismic City
Council.

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He was a key participant in the project,
Project 97, Project 07, Project 17 of the

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beginning Seismic Safety Council that
worked with the USGS to advance the

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seismic design method and improve the
earthquake ground motion maps.

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For those who don't know the project,
97, 07 and the Project 17 strongly

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encourages you guys to review the last
webinar given by Ron Hamburger and Sanaz

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Rezaeian.

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That's the that's the three project kind
of set the foundation for the modern

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seismic design maps and also making all
the major changes in the past 30 years.

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So our second speaker today is Nico Luco.

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Nico is a research civil engineer with
the US Geological Survey, USGS.

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There, he serves as the co-leader of the
Engineering Risk Project, primarily with

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the National Seismic Hazard Modeling
Project.

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He has served as the USGS liaison for the
BSSC on the Provisions Update Committee

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since 2005 and also served on the BSSC
Project 07 and the Project 17 committees.

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Our third speaker is Dr.

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C.B. Crouse. So Dr.

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C.B. Crouse has been a consultant in
earthquake engineering and engineering

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seismology seismology for 47 years since
receiving his Ph.D.

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in civil engineering from Caltech.

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He conducts seismic hazards and the cell
structure interaction studies and

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develops earthquake ground motion for
various types of projects throughout the

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world. He was a chairman of the
Subcommittees on the Ground Motion and

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the Foundation Design for the 2015 2020
NERHP also ASCE 7-16 on ASCE

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7-2022 seismic provisions was the past 
chair for the subcommittees on the

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ground motions for the 23 and 28 NEHRP.

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Also ASCE 7-05 and 7-10.

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In short, I think it's fair to say C.B.

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Is the go to guy. If you have any ground
motion questions and that's all I heard

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from the colleagues without that's the.

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Glad to have our three renowned speaker
here today with us.

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So I will pass this to Charlie.

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Before we start, I want to have a cover,
a few quick housekeeping items so all the

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participants will be able to type your
questions through the Q&A buttons.

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Everyone's muted, except the speaker so
strongly encourage you guys taping your

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questions throughout the Q&A button and
during presentation.

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We will try to answer all the questions
at the end.

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Second, the session will be recorded.

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The recording will be available on the
BSSC website.

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Also, the Certificate for the
Professional Development Hours PDA.

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Also the continuing education hours.

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See useful. Eia and ICC will be provided.

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Look forward follow up emails for both
the recording and the certificates.

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With that, I will pass this to Charlie.

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Thank you, everyone. Charlie?

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Yep.

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Thank you, JQ.

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I am going to talk about the first of the
three talks.

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Development of the new multi period
response spectra.

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It's actually quite a complex process and
I'll be giving you kind of a view from

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50,000 feet overview of the process.

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First, I want to say to all those that
are designer types in the audience that

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these changes to the ground motions
really don't affect the procedures that

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are used in, say, other chapters of of
the provisions and ASCE 7 for design.

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So the ELF procedures in Chapter 12
remain largely the same as do the

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multi-tiered response spectrum
procedures.

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So we're really changing the ground
motion parameters, better view of the

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spectra that go into multi into response
spectrum analysis, but not the actual

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ways that engineers calculate design
forces.

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The ground motion parameters are
available online.

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They're archived in a database that the
USGS has put together.

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They're available through a USGS web
service and other user friendly services

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that provide the values.

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And for those that do site specific
ground motion analysis or need site

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specific ground motion spectra.

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The Chapter 21 now permits the multi
period spectra of of this of 7-22 to be

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used for that purpose.

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And they are also available online.

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So why do we do this.

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Well. These response spectra multi
response spectra provide a better

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collective. That characterization of the
frequency content of the ground motions,

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they enhance the reliability of the
design parameters that are designed

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derived from these ground motions.

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They make better use of available earth
science, namely the 2018 update of the

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USGS national seismic hazard model.

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They eliminate a onerous requirement of
7-16 for site specific analysis at sites

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of certain soft cell sites that were put
in there to solve a problem, which I will

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discuss briefly later.

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And but as I said before, they do not
really change the procedures that

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engineers use for design.

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They affect three, four chapters,
chapters 11, 20, 21 and 22, which I will

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go through summarizing the major changes
in those chapters, Chapter 11, which

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really defines the seismic criteria
required for a design.

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Now specifies ground motion parameters,
SMS, SM1 one

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PGA based on these new multi period
spectra.

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That are archived in the USGS Seismic
Design Geo database.

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Accessible by users, given the location
and size class and a major change in 11

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was the deletion of site coefficients FA
and FV.

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Because the spectra contain site
amplification, it's built into the

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parameters of the spectra design
parameters and the spectra.

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So site site coefficients are gone.

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And as I mentioned, those changes to site
specific, those changes to the

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requirements for site specific analysis
have gone back essentially to where they

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were two cycles ago.

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So really the only time that site
specific analysis is required is for

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sites that are have particular problems
such as site class F, although site

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specific analysis can still be used any
time the user wants to.

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In Chapter 20, the major changes included
the addition of three new site classes,

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which are now based on shear wave
velocity.

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And I think CVH is going to talk a little
bit more about the specifics of that in

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Chapter 21, which is really the chapter
that defines how to develop site specific

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spectra, but it also defines how these
multivariate spectra were created from

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the science of the USGS.

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A couple of important changes there were
change to the deterministic marker mce

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r risk targeted ground motions or
deterministic ground motions that were

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based previously on a characteristic
earthquake or earthquake based on a

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characteristic magnitude, the science
change.

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The magnitude went away and we had to
come up with scenario earthquakes, which

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are now based on a look at the underlying
seismic hazard of the site to see which

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faults govern the site and then to pick a
scenario earthquake from that

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de-aggregation also of importance.

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The definition of the 1 second parameter
has changed significantly, and I'll

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describe that a bit more later in Chapter
22, which is the chapter that contains

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all the maps of the ground motions.

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That chapter is updated to incorporate
the most current science of the USGS.

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And because there's far too much data,
the maps now show a maps of SMS

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and SM1 strictly for default site
conditions because the data is really too

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voluminous to put in the maps.

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They're not they're not particularly
useful anyway for most sites.

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So it's really online sources of of the
data.

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So traditionally spectra have been
defined by a two period spectrum two

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period because it's defined at in the in
the acceleration domain by response at

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about 0.2 seconds and in the, in the
velocity domain by response at 1/2,

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assuming that the velocity domain
decreases in response as one over t, this

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was found to be a problem in 2000 in the
ASCE 7-10 and earlier editions

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that were underestimating the velocity of
domain.

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So as I said, a problem was discovered as
we were going through the development of

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ASCE 7-16, we looked back and said maybe
we should add some more periods besides

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1 second and the velocity domain and
discovered that in fact response at 2, 3

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and 4 seconds was not obeying the one
over T assumption of the standard

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spectrum, and particularly for softer
sites where the site coefficients were

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not adequate to get up to the level we
wanted.

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So how bad for softer sites like site
class DX it's and it's as much as a

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factor of too low at longer periods of
response.

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Just to illustrate how much lower.

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I'm going to show a series of slides here
that were taken from the commentary of

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ASCE 7-16.

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I'm going to show a series of different
sites and sites and assumptions of

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hazard, but for each I'm going to start
with the character characterization of a

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multi period spectrum for reference site
conditions.

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The red spectrum the corresponding.

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MCE ground motions for a site class of
interest in this case, BC In this case,

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excuse me, Site class C, which is the
dark blue spectrum, and two thirds of

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that which is the spectrum we use for
design.

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And as it turned out.

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The coefficients of ASCE 7-16 without any
other adjustment.

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We're doing a fine job of emulating that
design spectrum.

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The Green indicates areas that are a
little bit conservative, but no areas of

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significant underestimation.

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Repeating this process for site class DX
You'll notice that as I move from site

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class DC to C today, you'll see the peaks
of the spectrum move to the right,

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emphasizing that the softer the site, the
more the more the response occurs in the

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velocity domain.

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So again, we go back and take the
coefficient and site coefficients and and

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construct the design spectrum and it and
it significantly underestimates the

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corresponding underlying multi period
spectrum.

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I repeat this again for site class E
peaks move over further, the story gets

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worse. This is for a magnitude seven and
if I were to use equations for magnitude

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eight, it gets even worse.

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So we see that softer sites, larger
magnitudes significantly underestimate

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spectrum. We would like these
coefficients to be emulating.

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I just want to footnote here that these
spectra these spectra are drawn using NGA

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West one ground motion equations.

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We are now using NGA West to ground
motion equations which have to have about

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the same amount of content in the
velocity domain, but a little bit less in

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the acceleration domain.

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So the acceleration domain is not quite
as bad as this picture characterizes, but

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we have a problem and we had to have a
solution.

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So in six, 7-16, the solution, the OP
solution that was decided upon

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by the 7-16, the, in the NEHRP
provisions, 2015 NEHRP provisions was to

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require a site specific analysis.

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Whenever we were, we realized that the
the coefficients, the site coefficients

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were not getting the job done.

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This. This occurs in a lot of sites and
it's onerous to require site specific for

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all these sites for most buildings.

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So to to avoid that there are exceptions
in 16 where we think we have conservative

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values. Can they be used for design in
lieu of doing a site specific analysis?

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So for site class C, any site that was
over point two GS at a reference site

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conditions 1/2 requires a site specific
analysis, but can be avoided if you in

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essence, the designer in essence bumps up
the the design coefficients by about

227
00:17:28.100 --> 00:17:30.530
50% in the velocity domain.

228
00:17:30.530 --> 00:17:33.620
This affects primarily mid-period
buildings.

229
00:17:35.630 --> 00:17:41.180
For site class E same problem, but both
in acceleration domains requiring a site

230
00:17:41.180 --> 00:17:42.770
specific analysis.

231
00:17:42.770 --> 00:17:48.170
But to avoid that, the designer can use
the short period coefficient for site

232
00:17:48.170 --> 00:17:53.300
class C, which is conservative with
respect to site class E, but for taller

233
00:17:53.300 --> 00:17:57.920
buildings that would be extremely
conservative and and site specific

234
00:17:57.920 --> 00:18:03.440
analysis would be required for site class
E for the taller buildings.

235
00:18:04.460 --> 00:18:07.280
How how common or widespread is the
problem?

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00:18:07.280 --> 00:18:13.340
Well, the orange areas of the map and
this is courtesy of USGS.

237
00:18:13.370 --> 00:18:18.740
The orange areas indicate those regions
in the United and the terminus United

238
00:18:18.740 --> 00:18:23.540
States where the ground motions at one
sector of the reference site condition

239
00:18:23.540 --> 00:18:26.180
ground motions at 1 second exceed point
two G.

240
00:18:26.210 --> 00:18:31.790
It's only about 10% of the contaminants
U.S., but it represents about 90% of the

241
00:18:31.790 --> 00:18:35.990
financial risk. So even though it's a
small, relatively small area, it's those

242
00:18:35.990 --> 00:18:41.720
areas of the strongest shaking that are
most influential of of the risk.

243
00:18:43.160 --> 00:18:48.110
The long term solution, which is what
topic I'm talking about really is the is

244
00:18:48.110 --> 00:18:52.070
that is the introduction of multi period
spectra into the 2020 NEHRP provisions

245
00:18:52.070 --> 00:18:53.690
and ASCE 7-22.

246
00:18:54.500 --> 00:18:58.280
So the idea is to define the ground
motions, not in terms of two reference

247
00:18:58.280 --> 00:19:04.070
site parameters, but in terms of these
these multi period spectrum, they can be

248
00:19:04.070 --> 00:19:08.540
used for multiple response spectrum
analysis or to select records for

249
00:19:10.280 --> 00:19:11.540
response history analysis.

250
00:19:12.620 --> 00:19:19.520
Those spectra also are used to derive
values of SDS and SD1 that best match the

251
00:19:19.520 --> 00:19:23.540
underlying spectrum. So to get around
that poor fit I showed you, we now derive

252
00:19:23.540 --> 00:19:27.740
values of SDS and SD1 directly from the
multi period spectrum.

253
00:19:29.380 --> 00:19:32.950
To use them. We need to know the site
location and the site class.

254
00:19:32.950 --> 00:19:39.250
And then as I mentioned earlier, the Web,
the USGS Web service can tap into the GEO

255
00:19:39.250 --> 00:19:41.170
database, provide the values.

256
00:19:41.770 --> 00:19:45.850
It's not super user friendly, and there
are more user friendly versions in the

257
00:19:45.850 --> 00:19:52.000
whole building design guide or the ASCE-7
hazard tool, which are no different than

258
00:19:52.000 --> 00:19:53.590
what they have been in past editions.

259
00:19:53.590 --> 00:19:58.270
So it's pretty much the same approach to
getting ground motion data, except now

260
00:19:58.510 --> 00:20:03.280
the user can obtain spectra as well as
values of design parameters.

261
00:20:04.160 --> 00:20:09.590
So just a little bit background on
Chapter 21 in particular, chapter section

262
00:20:09.590 --> 00:20:15.260
21.2, the the methods of Section 21.2
that are used to develop site specific

263
00:20:15.260 --> 00:20:21.770
spectra for a given site by a Geotech are
are the same rules that the USGS uses to

264
00:20:21.800 --> 00:20:25.340
transform their science into code.

265
00:20:25.340 --> 00:20:29.780
Consistent descriptions of spectra and
code consistent descriptions of ground

266
00:20:29.780 --> 00:20:30.890
motion parameters.

267
00:20:31.040 --> 00:20:35.030
So they're based on two things
probabilistic ground motions defined as a

268
00:20:35.030 --> 00:20:39.890
1% in 50 year, a level of shaking that
has a 1% and 50 year probability of

269
00:20:39.890 --> 00:20:46.040
collapse for an assumed hypothetical
building fragility that has a 10%

270
00:20:46.040 --> 00:20:50.420
probability of collapse given the ground
motions occur.

271
00:20:50.420 --> 00:20:53.960
If you're if you're a design engineer,
you don't need to worry about this.

272
00:20:53.960 --> 00:20:55.370
You just use the parameters.

273
00:20:55.370 --> 00:20:58.790
And if you're a geotech that does these
studies, you're already familiar with

274
00:20:58.790 --> 00:20:59.870
this process.

275
00:21:00.920 --> 00:21:05.690
But it's an interesting process to derive
risk targeted ground motions.

276
00:21:06.170 --> 00:21:09.170
There is a second definition of
deterministic ground motions.

277
00:21:09.890 --> 00:21:14.870
They're based now on scenario based, 84th
percentile ground motions.

278
00:21:18.920 --> 00:21:21.170
That's a new a new version, as I
mentioned.

279
00:21:22.870 --> 00:21:25.810
They are derived from probabilistic
ground motion hazard.

280
00:21:26.380 --> 00:21:30.460
That's new. And they're not less than a
deterministic lower limit, which really

281
00:21:30.460 --> 00:21:34.990
says when you're to use probabilistic
ground motions and when you might be able

282
00:21:34.990 --> 00:21:41.830
to use deterministic ground motions to
determine design values, and that's done

283
00:21:42.070 --> 00:21:47.380
in the Section 21.2.3, which says take
the lesser of the two, which always is

284
00:21:47.380 --> 00:21:52.600
probabilistic in the regions of moderate
and lower seismicity and could be either

285
00:21:52.600 --> 00:21:55.420
probabilistic or deterministic in the
higher regions.

286
00:21:56.510 --> 00:22:01.970
So our approach for developing multi
period spectra was different, whether we

287
00:22:01.970 --> 00:22:07.380
were within the Terminus United States or
whether we were outside the terminus

288
00:22:07.400 --> 00:22:13.910
United States because we do not yet have
all of the earth science in place for

289
00:22:13.910 --> 00:22:16.400
sites outside the terminus of the United
States.

290
00:22:16.400 --> 00:22:23.600
So we are we rely on the 2018 national
seismic hazard model, the USGS, for the

291
00:22:23.600 --> 00:22:30.020
ground motions, which fully describe all
response periods of interest for all site

292
00:22:30.020 --> 00:22:34.310
classes of interest in in the terminus
U.S.

293
00:22:34.370 --> 00:22:41.150
outside of the terminus U.S., which
includes Alaska, Hawaii and other U.S.

294
00:22:41.240 --> 00:22:46.250
and U.S. territories, Guam and Puerto
Rico, for example.

295
00:22:47.150 --> 00:22:50.810
We only know values of SS and S1.

296
00:22:50.940 --> 00:22:56.720
That's that's just two accelerations for
one set of site conditions.

297
00:22:56.870 --> 00:23:01.670
And we might also know tl tl is the
transition period between the velocity

298
00:23:01.670 --> 00:23:03.170
and displacement domains.

299
00:23:03.290 --> 00:23:08.450
It is a clue about the magnitude that
controls the hazard at the site, which

300
00:23:08.480 --> 00:23:10.550
influences the spectrum shape.

301
00:23:10.940 --> 00:23:16.340
So we had to come up with a way of taking
values of SS and S1 and TL and developing

302
00:23:16.340 --> 00:23:18.470
a full suite of multiple period spectra.

303
00:23:18.680 --> 00:23:23.960
And that was done in a project that
resulted in a report FEMA P-2078.

304
00:23:23.960 --> 00:23:28.490
You can obtain it online if you're
interested, but it basically developed

305
00:23:28.490 --> 00:23:35.900
generic shapes based on SS, S1 and TL
that could be anchored to the specific

306
00:23:35.900 --> 00:23:41.900
site, specific values of SS S1 and TL to
create site specific spectra for sites

307
00:23:41.900 --> 00:23:43.700
outside the contaminants U.S.

308
00:23:43.700 --> 00:23:48.470
So an example of multi period spectra,
these are based on the deterministic

309
00:23:48.470 --> 00:23:54.320
lower limit. Just an example somewhere in
the database are these sorted data.

310
00:23:55.280 --> 00:24:02.930
They describe response at 21 response
periods from 0 to 10, 10 seconds as well

311
00:24:02.930 --> 00:24:07.760
as PGA. And they do it for each of the
eight hypothetical site classes from A to

312
00:24:07.760 --> 00:24:15.710
E. If you're a user, you would say, Well,
I think my site is D and the USGS

313
00:24:15.710 --> 00:24:20.300
Web service and or the user friendly
services such as the hazard tool would

314
00:24:20.300 --> 00:24:27.410
return a spectrum such as you see in
under, under in the column, under site,

315
00:24:27.410 --> 00:24:33.290
class D. This can be done for any site in
in the western or central and eastern

316
00:24:33.290 --> 00:24:38.900
U.S.. For sites outside the U.S., as I
said, concerning the U.S., I said we only

317
00:24:38.900 --> 00:24:41.100
have these three parameters to work with.

318
00:24:41.180 --> 00:24:43.550
Well, really. And PGA, which doesn't
help.

319
00:24:43.880 --> 00:24:46.670
Just a short period in 1/2 values.

320
00:24:46.670 --> 00:24:50.630
And we fill in the rest of the matrix
using those procedures.

321
00:24:50.780 --> 00:24:58.250
From that FEMA study, we checked to see
that the spectra that we generate from

322
00:24:58.250 --> 00:25:03.290
these generic shapes matches for sites in
California, for example, where we

323
00:25:03.290 --> 00:25:06.170
actually know the spectra and it does a
pretty good job. So we feel good about

324
00:25:06.170 --> 00:25:10.280
that. Some examples, spectra,
multivariate spectra are shown here again

325
00:25:10.280 --> 00:25:13.520
for the deterministic lower limit as just
an example set.

326
00:25:14.120 --> 00:25:18.020
What's important to take away from these
slides is to look at the slide on the

327
00:25:18.020 --> 00:25:22.370
right and look out at periods between one
and 3 seconds and see that there's a very

328
00:25:22.370 --> 00:25:29.180
large range of responses, different
responses for soft sites versus stiff

329
00:25:29.180 --> 00:25:31.610
sites. It has as much as a factor of
four.

330
00:25:32.150 --> 00:25:38.330
There is, in fact, a ratio of two between
site class C and D, which is which was

331
00:25:38.330 --> 00:25:44.330
the real impetus for adding three
additional site classes, BC, CD and D to

332
00:25:44.450 --> 00:25:47.420
create a little more finer gradation for
these spectrum.

333
00:25:49.170 --> 00:25:54.600
So here's our new site classes now
defined in terms of shear wave velocity,

334
00:25:55.680 --> 00:26:00.390
and the new ones are soft, rock dense and
loose sand.

335
00:26:02.310 --> 00:26:07.640
But the names are descriptive, but it's
the shear wave velocities that are

336
00:26:07.640 --> 00:26:13.400
important in terms of likelihood of one
of these, the very stiff sites are very

337
00:26:13.400 --> 00:26:16.250
unlikely. The very soft sites are very
unlikely.

338
00:26:16.250 --> 00:26:20.390
Looking at the superficial geology of
California, Oregon and Washington.

339
00:26:21.150 --> 00:26:26.870
site class C, D or CD accounts for over
95% of all the sites.

340
00:26:26.870 --> 00:26:32.900
So really it's those sites that govern
and those three sites site conditions C,

341
00:26:33.140 --> 00:26:38.550
CD and D, the envelope of those
conditions is what we call default cyclic

342
00:26:38.600 --> 00:26:41.510
conditions. If you don't know which one
you're in.

343
00:26:42.720 --> 00:26:50.430
So we have now improved site specific
spectra, if you will, multiple

344
00:26:50.610 --> 00:26:52.020
spectra of each site.

345
00:26:52.020 --> 00:26:57.870
We derive values of design parameters,
SDS, SD1 from the best fit of that two

346
00:26:57.870 --> 00:27:00.180
period spectrum to the multi period
spectrum.

347
00:27:00.180 --> 00:27:04.590
So we get rid of those glaring
shortcomings we had before.

348
00:27:06.420 --> 00:27:12.960
We have new rules in Section 21 that says
use 90% of the peak in the acceleration

349
00:27:12.960 --> 00:27:19.050
domain to regardless of where the period
might be, except not less than 0.2

350
00:27:19.050 --> 00:27:21.250
seconds in the velocity domain.

351
00:27:21.270 --> 00:27:25.980
Same concept use 90% of the peak response
and the velocity domain.

352
00:27:26.340 --> 00:27:28.410
Peak response might be at 3 seconds.

353
00:27:28.710 --> 00:27:33.990
If the peak response peak velocity
response is at 3 seconds, we would take

354
00:27:33.990 --> 00:27:40.260
the acceleration response at 3 seconds,
multiply by three and get a surrogate for

355
00:27:40.260 --> 00:27:46.590
1 second response, which when anchored,
which when a one over t shape is anchored

356
00:27:46.590 --> 00:27:51.450
to that 1 second, will give reasonable
values at longer periods.

357
00:27:51.450 --> 00:27:54.180
So it's really not a 1 second coefficient
anymore.

358
00:27:54.180 --> 00:27:59.520
It's a 1 second coefficient adjusted to
not underestimate response at longer

359
00:27:59.520 --> 00:28:04.110
periods. An example of this fitting
process is shown here for a very soft

360
00:28:04.110 --> 00:28:07.440
site. The.

361
00:28:09.210 --> 00:28:14.250
There's some specifics of the rules of
Section 21.4 that are in the little

362
00:28:14.250 --> 00:28:15.660
boxes, basically.

363
00:28:15.840 --> 00:28:20.190
As I said, 90% of short periods, 90% of
the velocity domain.

364
00:28:20.730 --> 00:28:26.250
The the red indicates that we're ever
going to be 10% un conservative at some

365
00:28:26.250 --> 00:28:31.230
period in the velocity, in the
acceleration domain and likewise in the

366
00:28:31.230 --> 00:28:34.290
acceleration domain. But we're also going
to be a little conservative at the

367
00:28:34.290 --> 00:28:39.000
corners. But all in all, this is a much
better fit than what we started with

368
00:28:39.000 --> 00:28:45.420
before, which was horribly
underestimating response at in this case

369
00:28:45.420 --> 00:28:47.460
at both acceleration and velocity
domains.

370
00:28:47.850 --> 00:28:54.690
So our new two two period spectrum is
based off these 90% values.

371
00:28:54.690 --> 00:29:01.770
And the intent the intent here is that it
it better and best replicates the

372
00:29:01.770 --> 00:29:04.440
underlying site specific multi period
spectrum.

373
00:29:04.440 --> 00:29:08.070
As a matter of practice, we now are
really encouraging that the multi period

374
00:29:08.070 --> 00:29:12.060
spectrum be used for design rather than
the two period spectrum.

375
00:29:12.060 --> 00:29:15.990
But there may be certain sites outside
the United States that still will be

376
00:29:15.990 --> 00:29:17.850
required to use a two period spectrum.

377
00:29:18.540 --> 00:29:19.590
Okay. So.

378
00:29:21.870 --> 00:29:27.840
Closing, I'd like to show some examples,
comparisons between where we were in ASCE

379
00:29:27.840 --> 00:29:35.760
7-10, where we got to an ASCE 7-16 and
where we are now in ASCE 7-22 by

380
00:29:35.760 --> 00:29:41.610
comparing two period spectra as well as
showing the multi period spectrum of

381
00:29:41.610 --> 00:29:43.170
ASCE 7-22.

382
00:29:43.260 --> 00:29:48.840
I'm going to do it for four sites or
Irvine and Southern California, which is

383
00:29:48.840 --> 00:29:55.710
a site controlled by probabilistic ground
motions for a smaller magnitude, a not

384
00:29:55.710 --> 00:30:01.410
small but smaller than maximum magnitude
7 to 7 and a half type earthquake.

385
00:30:01.440 --> 00:30:08.280
San Mateo, which is in northern
California, relatively close to the San

386
00:30:08.280 --> 00:30:13.170
Andreas Fault, where the ground motions
are controlled by deterministic MCE

387
00:30:13.170 --> 00:30:18.870
ground motions and a larger magnitude and
type eight event on the San Andreas

388
00:30:19.410 --> 00:30:20.430
spectrum from.

389
00:30:21.600 --> 00:30:27.240
Anchorage, which is an outside outside
the terminus us and a site in Memphis

390
00:30:27.240 --> 00:30:31.440
which illustrates what's going on with
the new ground motions in the central and

391
00:30:31.440 --> 00:30:39.210
eastern U.S.. So starting with Irvine and
all these plots are exactly the same

392
00:30:39.210 --> 00:30:44.400
data, the left hand plot is simply
showing response period as a as a

393
00:30:44.400 --> 00:30:45.660
logarithmic scale.

394
00:30:45.660 --> 00:30:49.590
And on the right, it's linear scale from
0 to 5 seconds.

395
00:30:50.220 --> 00:30:54.270
The plot on the right is what most
engineers are familiar with in terms of

396
00:30:54.270 --> 00:30:55.370
looking at spectra.

397
00:30:55.380 --> 00:31:01.230
The red, the bright red is the ASCE 7-10
2 period spectrum.

398
00:31:01.230 --> 00:31:05.820
You're going to see that it is
consistently lower at longer periods than

399
00:31:05.820 --> 00:31:07.980
either 16 or 22.

400
00:31:08.010 --> 00:31:12.180
For the Irvine site, they might have over
adjusted a bit.

401
00:31:12.180 --> 00:31:16.830
The orange curve is a little bit higher
for the 7-16 that it turns out that we

402
00:31:16.830 --> 00:31:20.580
needed in in 7-22.

403
00:31:21.270 --> 00:31:28.410
But all in all, there was good agreement
between 16 and 22 and and and 7-10 was

404
00:31:28.410 --> 00:31:30.510
low by 30% or 50%.

405
00:31:31.680 --> 00:31:37.140
Looking at San Mateo, which is a site
controlled by stronger ground motions,

406
00:31:37.140 --> 00:31:38.430
deterministic ground motions.

407
00:31:38.430 --> 00:31:45.200
We can see a more significant
underestimation of the long period

408
00:31:45.220 --> 00:31:50.580
response and also a short period of
response by 7-10, that's the red curve.

409
00:31:50.580 --> 00:31:56.040
So our adjustment in 7-16, our bump
factor in 7-16 solved a part of the

410
00:31:56.040 --> 00:32:00.750
problem and the rest of the problem is
now solved in 7-22.

411
00:32:00.750 --> 00:32:07.620
So a significant increase in 7-22 from
that of 7-10, approximately a factor of

412
00:32:07.620 --> 00:32:09.930
two at longer periods that would be.

413
00:32:11.840 --> 00:32:17.630
Mid-rise structures, commercial
structures, tall, maybe some taller

414
00:32:18.860 --> 00:32:20.300
residential structures.

415
00:32:22.570 --> 00:32:23.920
Looking to Alaska.

416
00:32:24.010 --> 00:32:31.600
We derived the spectra showing here based
on our generic shapes and the values of

417
00:32:31.610 --> 00:32:33.740
SS and S1 for Alaska.

418
00:32:33.760 --> 00:32:39.850
Again, emphasizing that the 7-10 version
was underestimating ground motions by

419
00:32:39.850 --> 00:32:42.460
about a factor of two and last.

420
00:32:42.730 --> 00:32:47.740
Looking at central and eastern United
States, we see a very different shape to

421
00:32:47.740 --> 00:32:52.690
the spectrum. The the site specific multi
period response spectrum, which are the

422
00:32:52.690 --> 00:32:56.530
diamonds in the central and eastern
United States.

423
00:32:56.680 --> 00:33:02.430
Even for softer sites, the spectrum peaks
at ten or 20 hertz.

424
00:33:02.440 --> 00:33:06.490
It does not peak at 0.2 seconds or 0.5
seconds.

425
00:33:07.510 --> 00:33:12.670
We we didn't want to end up designing for
peak response at ten or 20 hertz.

426
00:33:12.670 --> 00:33:14.680
So the code decided that.

427
00:33:16.560 --> 00:33:18.990
Any other code decided that the.

428
00:33:20.100 --> 00:33:28.050
Limit on determining short period
accelerations would be based on periods,

429
00:33:28.050 --> 00:33:30.720
not less, not less than 0.2 seconds.

430
00:33:30.720 --> 00:33:35.160
So you'll see that there's a peak
sticking up there quite a ways up.

431
00:33:35.160 --> 00:33:37.520
In fact, we avoided the peak.

432
00:33:37.530 --> 00:33:40.290
We have very similar ground motions to
what we had before.

433
00:33:40.290 --> 00:33:45.510
Frankly, in the central and eastern
United States, word of caution would be

434
00:33:45.510 --> 00:33:50.370
here that this is fine for building
design might not be so.

435
00:33:52.670 --> 00:33:57.500
Appropriate for looking at the at the
response of high frequency equipment in

436
00:33:57.500 --> 00:33:58.910
the structure, for example.

437
00:33:59.540 --> 00:34:02.090
So we're probably underestimating demands
on equipment.

438
00:34:02.940 --> 00:34:04.530
But fine for design.

439
00:34:04.530 --> 00:34:07.020
Building design. So in conclusion.

440
00:34:07.900 --> 00:34:11.860
Fine. As usual, we get the ground motions
from the websites.

441
00:34:11.860 --> 00:34:16.810
We can get spectra now from the websites
as well as design parameters.

442
00:34:17.410 --> 00:34:22.240
The procedures of the off procedures of
WebTV remain largely the same.

443
00:34:22.390 --> 00:34:27.810
There was a small change at the at the
very end of the code cycle that said you

444
00:34:27.820 --> 00:34:33.040
you could get ah, derive The values of
SDS.

445
00:34:33.070 --> 00:34:39.580
SD1 directly from your the multi period
response spectrum of the site of interest

446
00:34:39.580 --> 00:34:42.790
rather than using the values provided by
the website.

447
00:34:42.850 --> 00:34:45.400
In case you wanted to get a little finer.

448
00:34:46.580 --> 00:34:51.170
Measure of the design parameters at the
specific period of your structure and the

449
00:34:51.170 --> 00:34:52.670
multi period response spectra.

450
00:34:53.030 --> 00:34:55.370
Procedures of Chapter 12 remain the same.

451
00:34:55.730 --> 00:35:03.100
So with that, I will stop sharing my
screen and turn it over to Nico

452
00:35:03.110 --> 00:35:06.470
Luco who will tell us about the.

453
00:35:11.800 --> 00:35:12.130
Mm hmm.

454
00:35:14.610 --> 00:35:16.080
Thank you, Charlie.

455
00:35:18.450 --> 00:35:21.510
Thanks to BSSC for organizing this.

456
00:35:22.830 --> 00:35:24.240
All right.

457
00:35:24.760 --> 00:35:31.450
All right. So I am going to talk about
see, here's some

458
00:35:31.450 --> 00:35:38.650
examples of the changes, the numerical
changes to the ground motion

459
00:35:38.650 --> 00:35:45.220
values that result from these updates
that Charlie has talked about.

460
00:35:45.230 --> 00:35:52.390
And I'll try to dig into those changes
and dissect what caused those changes for

461
00:35:52.390 --> 00:35:54.040
different locations.

462
00:35:56.030 --> 00:36:03.890
So as an outline, I'm showing here that
sections of the commentary to Chapter 22

463
00:36:03.890 --> 00:36:10.460
of the 2020 NEHRP provisions, I would
refer to that basically I'll be giving a

464
00:36:10.460 --> 00:36:17.210
short version presentation of much more
information that you can get there.

465
00:36:17.870 --> 00:36:22.460
So the first two sections of that
commentary talk about at least

466
00:36:22.460 --> 00:36:28.710
conceptually modifications to the use of
our but also G promotions.

467
00:36:28.730 --> 00:36:35.960
First from Project 17 recommendations and
I'll go over those again just to clarify

468
00:36:35.960 --> 00:36:43.190
which what those are and also the
modifications from the 2018 USGS National

469
00:36:43.190 --> 00:36:49.460
Seismic Hazard Update, which was talked
about in more depth in a previous

470
00:36:50.390 --> 00:36:58.220
webinar. Then I will give some of the
numerical examples of changes in our

471
00:36:58.220 --> 00:36:59.420
values at least.

472
00:37:00.320 --> 00:37:01.730
These next three sections.

473
00:37:01.730 --> 00:37:08.320
Talk a little bit more about how images
of our emotions are derived, how our

474
00:37:10.370 --> 00:37:16.080
emotions are derived, and also the long
period of transition maps.

475
00:37:16.130 --> 00:37:18.500
I won't cover that in this presentation.

476
00:37:19.500 --> 00:37:21.880
Here's a little bit about that from CB.

477
00:37:22.250 --> 00:37:26.870
And then lastly, I'll talk about just
elaborating on what Charlie mentioned,

478
00:37:26.870 --> 00:37:34.040
that USGS seismic design, geo database,
web service that goes along with it.

479
00:37:37.020 --> 00:37:42.780
All right. So to start first with the
modifications to design promotions that

480
00:37:42.780 --> 00:37:50.160
are resulting from updates to the USGS
national seismic hazard model for

481
00:37:50.190 --> 00:37:57.630
2018. So as I talked more about these
four changes, here is this

482
00:37:57.630 --> 00:38:04.740
2018 USGS model incorporates the East
motion models that are new.

483
00:38:04.740 --> 00:38:09.660
And really using those new ground motion
models is what allowed us to produce

484
00:38:09.660 --> 00:38:16.710
multiple spectra for multiple site
classes, unlike the previous

485
00:38:16.710 --> 00:38:20.550
generation of ground motion models for
the East.

486
00:38:21.360 --> 00:38:27.660
The second item here is incorporating
deep sedimentary basin effects, at least

487
00:38:27.660 --> 00:38:33.690
in Los Angeles, Seattle, San Francisco
and Salt Lake City areas.

488
00:38:33.700 --> 00:38:38.610
So these are areas where we had good
information about bass and depths, and we

489
00:38:38.610 --> 00:38:44.610
think that the ocean models available do
a reasonable job at estimating what the

490
00:38:44.610 --> 00:38:48.180
effects of those bass and depths are.

491
00:38:49.110 --> 00:38:52.650
In particular, this doesn't affect short
period motions, but you will see in

492
00:38:52.650 --> 00:38:56.340
effect 1/2 and beyond motions.

493
00:38:56.670 --> 00:39:00.720
Thirdly, here, it's a minor update, but
we always want to make sure that we're

494
00:39:01.140 --> 00:39:06.990
looking at the earthquakes that have
occurred up to the current time, because

495
00:39:06.990 --> 00:39:12.390
we use those earthquakes to think about
what could occur in the future,

496
00:39:12.390 --> 00:39:16.770
especially off the faults that we have
more information on.

497
00:39:17.300 --> 00:39:24.060
And the fourth item here, then,
relatively minor changes to the weighting

498
00:39:24.060 --> 00:39:27.050
of ground motion models in the western
U.S.

499
00:39:27.060 --> 00:39:31.800
And again, this was really done because
some of the motion models wouldn't allow

500
00:39:31.800 --> 00:39:37.170
us to get the full multi period response
vector for different classes that we

501
00:39:37.170 --> 00:39:39.520
wanted. All right.

502
00:39:39.520 --> 00:39:46.000
So those are the USGS triggered changes,
Project 17, which you heard a little bit

503
00:39:46.000 --> 00:39:53.800
about and talked about in a previous
webinar, how do we take the

504
00:39:53.800 --> 00:39:59.400
USGS science and translate that into new
design spectrum and design ground

505
00:39:59.410 --> 00:40:05.050
motions? So the Project 17
recommendations were modifications to

506
00:40:05.080 --> 00:40:06.310
slight class effects.

507
00:40:06.350 --> 00:40:07.720
You heard that from Charlie.

508
00:40:07.720 --> 00:40:14.440
But instead of using site coefficients to
account for soil effects or effectively

509
00:40:14.770 --> 00:40:21.490
taking directly from USGS hazard results
that are already for different site

510
00:40:21.490 --> 00:40:29.470
classes, the second modification Charlie
talked about was for at least for systems

511
00:40:29.470 --> 00:40:36.340
and of one that those are defined longer
just as values at 0.2 second and 1/2.

512
00:40:36.340 --> 00:40:42.820
But they look more broadly at the multi
period spectrum to come up with a best

513
00:40:42.820 --> 00:40:44.450
fit values.

514
00:40:45.280 --> 00:40:49.420
The third on this list Charlie mentioned,
I will go to a little bit more detail on

515
00:40:49.420 --> 00:40:54.820
the third and fourth. And this is because
Charlie didn't have time to set

516
00:40:54.830 --> 00:40:58.630
deterministic caps on otherwise
probabilistic motions.

517
00:40:58.630 --> 00:41:01.660
There's just a little change in how we do
that.

518
00:41:01.690 --> 00:41:05.500
And then I'll describe and then maximum
direction scale factors.

519
00:41:05.650 --> 00:41:13.060
So what most of the motion models just
give is geometric, mean or immediate, an

520
00:41:13.060 --> 00:41:20.170
average horizontal motion for provisions,
ASCE 7, etc.

521
00:41:20.320 --> 00:41:25.180
There's a maximum spectral acceleration
or horizontal that's used.

522
00:41:25.180 --> 00:41:27.760
And so we have factors to go between the
two.

523
00:41:28.690 --> 00:41:33.700
So starting with that last one, first is
new maximum interaction scale factors.

524
00:41:33.700 --> 00:41:41.510
We actually knew of four in the cycle
that produced 2015 meter

525
00:41:41.590 --> 00:41:47.620
provisions and there was a resource paper
they're shown here that talked about

526
00:41:47.620 --> 00:41:54.100
these updated maximum response scale
factors where they come from different

527
00:41:54.100 --> 00:41:56.180
than the previous is, etc.

528
00:41:57.610 --> 00:42:05.530
To show those numerically, here's a plot
spectral periods, the x axis and x max

529
00:42:05.620 --> 00:42:13.000
scale nice direction scale factor on the
y axis and the blue are the factors that

530
00:42:13.000 --> 00:42:17.040
were being used since 2009 here.

531
00:42:17.090 --> 00:42:22.390
Provisions as E 17 are also used in C
seven.

532
00:42:22.390 --> 00:42:29.080
Six in green are extracts and scale
factors that come from a study that was

533
00:42:29.080 --> 00:42:36.950
part of the two program and published by
Charlie and Baker in a couple

534
00:42:36.950 --> 00:42:38.110
of publications.

535
00:42:38.110 --> 00:42:39.370
That's the Green Line.

536
00:42:39.520 --> 00:42:46.360
And what we did both in this research
paper and for 29 year provisions is is

537
00:42:46.600 --> 00:42:53.080
a smoothing essentially of site and
beaker extraction scale factors.

538
00:42:53.080 --> 00:43:00.030
And you can see from that at 0.2 seconds
down here that and going from 1.1 to 1.2.

539
00:43:00.040 --> 00:43:08.020
So about a 10% increase at 1/2 going down
from 1.3 to 1.25, just about a

540
00:43:08.020 --> 00:43:09.490
5% decrease.

541
00:43:09.490 --> 00:43:15.430
But at longer periods, if you were doing
site specifics and looking at longer

542
00:43:15.430 --> 00:43:20.800
periods in previous codes, those
extraction scale factors made a big

543
00:43:20.800 --> 00:43:22.300
difference. And they were important.

544
00:43:22.300 --> 00:43:27.610
So important to include the new factors
now with the multi period spectrum.

545
00:43:30.140 --> 00:43:34.370
Sorry. So now deterministic caps.

546
00:43:34.370 --> 00:43:39.680
So this is essentially in a nutshell the
change that was made to the deterministic

547
00:43:40.070 --> 00:43:46.610
caps. This is a section from Chapter 21,
the site specific section, which again is

548
00:43:46.610 --> 00:43:53.460
what really follows in going from its
national seismic hazard model to these

549
00:43:54.110 --> 00:43:56.680
are g motions.

550
00:43:56.690 --> 00:44:01.790
So as you can see here, really what
changes the change in terminology, but an

551
00:44:01.790 --> 00:44:06.410
important change in terminology from
characteristic earthquakes to scenario

552
00:44:06.410 --> 00:44:14.000
earthquakes. Characteristic earthquakes
have certain definition in the seismology

553
00:44:14.360 --> 00:44:19.820
community. And really there's a move away
from defining characteristics of

554
00:44:19.820 --> 00:44:26.420
earthquakes. For example, our USGS model,
California, part of that model no longer

555
00:44:26.420 --> 00:44:28.850
defines characteristic earthquakes.

556
00:44:28.850 --> 00:44:30.650
That was an issue we had to resolve.

557
00:44:31.550 --> 00:44:36.830
And the other change here is just
removing this active word from faults.

558
00:44:37.550 --> 00:44:41.870
That was always a bit subjective in past
cycles.

559
00:44:41.870 --> 00:44:47.830
We came up with some rules for looking at
that with two senses that follow.

560
00:44:47.840 --> 00:44:55.790
We think we improved the active faults,
so that's the first sentence here.

561
00:44:55.790 --> 00:44:59.670
Additional sentence says that these
scenario earthquakes come from the

562
00:44:59.690 --> 00:45:06.020
aggregation or disaggregation of of the
probabilistic ground motions, the

563
00:45:06.020 --> 00:45:08.240
spectral accelerations at each period.

564
00:45:08.660 --> 00:45:12.450
So these scenario earthquakes are now
coming from disaggregation, energy

565
00:45:12.500 --> 00:45:18.050
aggregation. We're moving towards the
term this aggregation, this predated

566
00:45:18.050 --> 00:45:23.990
that. And then the second sentence here,
it says the scenario, earthquakes that

567
00:45:23.990 --> 00:45:29.870
contribute 10%, less than 10% of the
largest contribution to the hazard at

568
00:45:29.870 --> 00:45:31.790
each period. So be ignored.

569
00:45:31.790 --> 00:45:37.730
And that's basically a way of identifying
faults that aren't very active and they

570
00:45:37.730 --> 00:45:40.520
don't contribute to the hazard.

571
00:45:40.520 --> 00:45:47.240
And that's a more quantitative way to
define those relatively inactive faults.

572
00:45:48.140 --> 00:45:55.550
So here's a quick example table again
from the chapter is My Feet from chapter

573
00:45:55.550 --> 00:46:00.200
20 and the commentary of that chapter.

574
00:46:00.760 --> 00:46:06.860
And so we've got different spectral
periods of just this is showing a snippet

575
00:46:06.880 --> 00:46:12.890
but from point 2 to 1 second and these
are showing the scenario earthquakes that

576
00:46:12.890 --> 00:46:15.950
result from disaggregation.

577
00:46:16.190 --> 00:46:19.940
So this is San Jose, California site.

578
00:46:20.030 --> 00:46:25.610
So this aggregation is telling us there's
contributions to the hazard from, hey,

579
00:46:25.610 --> 00:46:29.600
we're in Calaveras, San Andreas and also
Silver Creek.

580
00:46:30.110 --> 00:46:34.310
You can see the magnitudes here, which
can change a little bit with spectral

581
00:46:34.310 --> 00:46:41.050
period and the amount of contribution
these different earthquake faults have.

582
00:46:41.120 --> 00:46:45.350
Right. Hayward being the largest that you
could see here is the contribution to the

583
00:46:45.350 --> 00:46:51.110
hazard from Silver Creek is pretty small
and it's less than 10% of the biggest

584
00:46:51.110 --> 00:46:55.010
contribution in these 50% ish
contribution.

585
00:46:55.010 --> 00:46:57.110
So these are all less than 5%.

586
00:46:57.110 --> 00:47:01.640
And therefore, Hart, Silver Creek would
be considered inactive and wouldn't be

587
00:47:01.970 --> 00:47:05.150
used for deterministic calculation.

588
00:47:05.600 --> 00:47:11.840
And that can have a big impact on the
motions because in a probabilistic sense,

589
00:47:11.840 --> 00:47:15.680
Silver Creek doesn't matter too much if
you include it or not because it's

590
00:47:15.680 --> 00:47:17.270
relatively inactive.

591
00:47:17.270 --> 00:47:21.890
But if you're deterministically,
calculating promotion, saying I'm not

592
00:47:21.890 --> 00:47:27.220
considering how active the fault is,
whether you include Silver Creek or can

593
00:47:27.230 --> 00:47:28.490
make a big difference.

594
00:47:29.830 --> 00:47:36.330
Okay. So after now through conceptually,
those changes that occurred from both

595
00:47:36.350 --> 00:47:44.060
Project 17 recommendations and the USGS
2018 National Seismic Hazard Update, I'll

596
00:47:44.060 --> 00:47:46.400
talk about this third bullet here.

597
00:47:46.400 --> 00:47:51.110
Some example of changes to the values of
our ground.

598
00:47:51.620 --> 00:47:54.380
At least that's all we've got time for
today.

599
00:47:55.010 --> 00:48:01.100
So, for example, examples started with
the 2009 New Year provisions,

600
00:48:02.630 --> 00:48:10.280
Charlie, that put together this list of
34 cities across the US that are high

601
00:48:10.280 --> 00:48:15.080
hazard or high risk in a sense of high
populations.

602
00:48:15.560 --> 00:48:19.460
So you can see the Southern California
sites here, but we also have sites in

603
00:48:19.460 --> 00:48:24.440
Northern California at the Pacific
Northwest, Intermountain West and central

604
00:48:24.440 --> 00:48:26.120
and eastern US.

605
00:48:27.140 --> 00:48:34.370
So if you look in the commentary of the
Chapter 20 commentary of the NEHRP 2020

606
00:48:34.370 --> 00:48:37.550
provisions, you'll see tables like this.

607
00:48:37.550 --> 00:48:41.450
And this is, again, just showing part of
that table for the Southern California

608
00:48:41.450 --> 00:48:43.910
sites that show.

609
00:48:44.380 --> 00:48:49.300
So those are for the reference site
condition, which is now called B.C.

610
00:48:49.310 --> 00:48:56.080
site class and for SMEs in this case for
the default site class that used to be

611
00:48:56.090 --> 00:49:04.090
site, class D now is looking across a
class several times around site

612
00:49:04.170 --> 00:49:10.120
class. So it showed values for HSC 710
just to give some perspective.

613
00:49:10.130 --> 00:49:16.380
And then of course it's 7-16 so we can
look at the changes to the 2020 NEHRP

614
00:49:16.380 --> 00:49:23.390
provisions. So you'll find tables of
these, but we also have plots like this.

615
00:49:23.390 --> 00:49:31.130
So just to talk through these on the left
is applied to shows that ASCE 7-10 times

616
00:49:31.130 --> 00:49:37.700
five is the short period for the default
site class values versus ASCE 7-16

617
00:49:38.570 --> 00:49:46.040
values for these 34 different cities
across the US, that's the one that

618
00:49:46.700 --> 00:49:51.290
is solid. Here in the dashed line is a
plus or -15% difference.

619
00:49:51.650 --> 00:49:52.940
Same plot, right?

620
00:49:52.940 --> 00:50:00.710
Just showing as 716 on the x axis versus
the 2020 near provisions on the one.

621
00:50:01.040 --> 00:50:08.030
And so here, for example, looking at the
left plot, you can see then when we went

622
00:50:08.030 --> 00:50:15.860
from 7-10 to 7-16, there were changes
greater than 15% and 15% is a helpful

623
00:50:15.860 --> 00:50:21.110
number to look at. And smaller changes
can occur for lots of small changes

624
00:50:21.410 --> 00:50:28.520
adding up, but around 15% or 20%, there's
something significant that's that's a

625
00:50:28.520 --> 00:50:31.160
change that's changing the values.

626
00:50:31.160 --> 00:50:38.540
So about 20 of the 34 locations change,
more than 15% going from seven, ten,

627
00:50:38.900 --> 00:50:41.150
seven, 16 on the right.

628
00:50:41.150 --> 00:50:48.290
You can tell there aren't many changes,
more than 15% going from 7-16 to the

629
00:50:48.290 --> 00:50:53.180
2020 NEHRP provisions, at least in terms
of this sub RMS value.

630
00:50:53.600 --> 00:50:59.090
So once we do see this is for Vallejo,
there's a 34% increase, that's a big

631
00:50:59.210 --> 00:51:04.820
increase. And this is mostly due to that
change in the definition of deterministic

632
00:51:04.820 --> 00:51:09.860
caps. Really, that case is the definition
of active.

633
00:51:09.860 --> 00:51:14.660
The one we were using before really
didn't recognize some additional data

634
00:51:14.870 --> 00:51:22.460
that USGS uses from GPS measurements, and
the new definition helps with that.

635
00:51:23.090 --> 00:51:28.190
Sacramento is another place where it
changes about 30%, relatively small

636
00:51:28.190 --> 00:51:32.540
values comparatively, but pretty
significant changes there.

637
00:51:32.540 --> 00:51:38.060
And this is the case where the changes
really come mostly from the project 17

638
00:51:38.060 --> 00:51:42.350
changes and side class effects, where we
go from using site coefficients to

639
00:51:42.350 --> 00:51:49.190
directly using hazard results from the
USGS for site class like say, class D.

640
00:51:50.270 --> 00:51:55.280
And then this is a decrease, significant
decrease.

641
00:51:55.460 --> 00:52:00.650
This one is caused in part by the USGS
use of the east, but also the C class

642
00:52:00.650 --> 00:52:07.040
effects using not using CI coefficients
that we're actually up for the west but

643
00:52:07.040 --> 00:52:14.260
instead using results for different CI
classes calculated by USGS and their

644
00:52:14.360 --> 00:52:16.700
hazard modeling. All right.

645
00:52:17.020 --> 00:52:23.750
This is a similar figure I'll go through
more quickly here just for the sub one.

646
00:52:23.750 --> 00:52:27.730
So the 1/2 value so you can see from A.D.

647
00:52:27.740 --> 00:52:28.790
710 to C.

648
00:52:30.160 --> 00:52:31.930
There's a big difference in here.

649
00:52:31.930 --> 00:52:37.000
This plot, we've included this 1.5
multiplier that Charlie mentioned that

650
00:52:37.000 --> 00:52:42.190
was trying to account for this
recognition that at longer periods for at

651
00:52:42.190 --> 00:52:48.220
least four high hazard sites, higher
levels here, and softer site classes like

652
00:52:48.220 --> 00:52:53.920
the default that we were previously
underestimating, the design promotion

653
00:52:54.100 --> 00:53:01.040
values. And then on the right, you can
see the changes from 716 to the 2020

654
00:53:01.210 --> 00:53:02.260
NEHRP provisions.

655
00:53:02.260 --> 00:53:07.710
More values are changing is the San
Bernardino.

656
00:53:07.720 --> 00:53:13.030
These are mostly the definition of and
one that looks more broadly across multi

657
00:53:13.030 --> 00:53:19.870
period spectrum and deterministic capping
still has an effect here but also based

658
00:53:19.870 --> 00:53:21.040
on effects in this area.

659
00:53:21.040 --> 00:53:26.380
Start to factor in here for 1/2 or as
they didn't on the previous slide for

660
00:53:26.380 --> 00:53:33.250
short periods and then these eastern a
lot of these are non western sites with

661
00:53:33.250 --> 00:53:34.480
lower hazard.

662
00:53:34.510 --> 00:53:38.470
These locations mostly do the site class
effects and some of those are going to be

663
00:53:38.470 --> 00:53:44.680
because we're now have effectively we
have site modifications that are specific

664
00:53:44.680 --> 00:53:45.520
to the east.

665
00:53:47.160 --> 00:53:47.670
All right.

666
00:53:48.540 --> 00:53:51.450
Quickly to those are looking at the
ground motion values.

667
00:53:51.450 --> 00:53:57.660
You could also look at how seismic design
category changes to get a broader view of

668
00:53:57.660 --> 00:53:59.570
the impact of all these changes.

669
00:53:59.580 --> 00:54:05.370
So this is, again, is Chapter 22
commentary at least part of that table

670
00:54:05.370 --> 00:54:12.720
that shows that the seismic design
category is from 710 to 16, 2020 dinner

671
00:54:12.720 --> 00:54:15.680
provisions. So that's a lot of this.

672
00:54:16.680 --> 00:54:21.630
There aren't changes from seven, 10 to 16
over all.

673
00:54:21.930 --> 00:54:28.410
Seismic design can decrease that to 34
locations and not many changes.

674
00:54:28.410 --> 00:54:34.110
And those even those changes were seismic
design category E D maybe not the most

675
00:54:34.110 --> 00:54:35.610
significant impact.

676
00:54:35.610 --> 00:54:41.880
And then 4c7 16 to 2020 NEHRP provisions,
the seismic design category increased

677
00:54:42.330 --> 00:54:48.600
four of the 34 locations from D and
that's such a significant impact.

678
00:54:48.600 --> 00:54:52.680
And these were mostly due to
deterministic capping and and phasing

679
00:54:52.680 --> 00:54:57.390
effects. And here are maps of seismic
design category.

680
00:54:57.390 --> 00:55:01.530
So you could do the same thing
essentially using the oceans, the short

681
00:55:01.530 --> 00:55:08.100
period. And the 1/2 you could map seismic
design, category four on the left, 8716

682
00:55:08.100 --> 00:55:12.870
on the right, the 2020 NEHRP provisions,
they're broadly similar.

683
00:55:12.870 --> 00:55:17.940
You can already see that this plot
focuses on what are those areas where

684
00:55:17.940 --> 00:55:21.300
there are changes in the seismic design
category.

685
00:55:21.300 --> 00:55:25.210
So you could see some slivers of places
where probably not a big change in that

686
00:55:25.290 --> 00:55:31.890
motion. But that didn't change, did flip
from one across the threshold, from one

687
00:55:31.890 --> 00:55:37.050
seismic design category to another, and
then some a little bit deeper regions as

688
00:55:37.050 --> 00:55:44.460
well. So to summarize these numerical
changes, examples of

689
00:55:44.460 --> 00:55:50.340
numerical changes for default site
conditions, at least the short periods of

690
00:55:50.790 --> 00:55:57.330
motion values, they changed by less than
50%, 31 of the 34 locations, almost all

691
00:55:57.330 --> 00:56:03.330
of them for the 1/2 as one for default
site conditions.

692
00:56:03.480 --> 00:56:09.780
They changed less than this 15% or
interest in at 23 of the 34 locations.

693
00:56:09.780 --> 00:56:12.150
So that's a two thirds.

694
00:56:12.150 --> 00:56:18.900
But so there were some more significant
more sites that had changes at at 1/2.

695
00:56:18.900 --> 00:56:23.130
And again, that's not too surprising
because we're really moving towards this

696
00:56:23.130 --> 00:56:27.720
multi period response spectrum because of
issues we saw longer periods in the past

697
00:56:28.260 --> 00:56:33.660
and then the seismic design changes just
then that four of the 34 locations and

698
00:56:33.660 --> 00:56:41.490
again from site class D so most of these
changes in the project 17 modifications

699
00:56:41.490 --> 00:56:46.860
to site class effects or deterministic
cap caps, but some of the other ones are

700
00:56:47.550 --> 00:56:54.960
caused by other projects 17 modifications
or the 2018 USGS updates, particularly

701
00:56:54.960 --> 00:56:59.580
the incorporation of baseline effects in
the most recent USGS model.

702
00:56:59.910 --> 00:57:03.060
So this gives us some examples of the
changes.

703
00:57:03.060 --> 00:57:08.430
You could look at changes for other side
classes at other locations by using the

704
00:57:08.430 --> 00:57:14.990
USGS seismic design, web services and
also a PSC tool that's built on those Web

705
00:57:15.000 --> 00:57:21.110
services. So I'll spend a few minutes
showing those before we turn over to KB.

706
00:57:21.270 --> 00:57:27.450
Kraus So let's see the last bullet here
now.

707
00:57:29.340 --> 00:57:31.800
So Charlie referenced the U.S.

708
00:57:32.220 --> 00:57:34.530
seismic design database.

709
00:57:34.830 --> 00:57:36.210
What is that exactly?

710
00:57:36.870 --> 00:57:44.790
It's an archive of gridded motion values
and we archive at USGS system

711
00:57:44.790 --> 00:57:50.940
called Science Base, which is effectively
how we publish data, but the data can be

712
00:57:50.940 --> 00:57:57.150
downloaded from here archives somewhere
else by the BSSC in the ASCE so that we

713
00:57:57.150 --> 00:57:59.400
make sure it just goes away.

714
00:57:59.520 --> 00:58:05.910
You still have this this data, and so
it's sort of a web page interface and

715
00:58:05.910 --> 00:58:10.740
it's just showing one example of files
like here you can download files for the

716
00:58:11.460 --> 00:58:17.880
United States, the risk targeted motions,
also the deterministic 84 percentile

717
00:58:18.150 --> 00:58:25.330
motions. This is for site class A, these
first two and then site class B and this

718
00:58:25.350 --> 00:58:31.830
list goes on through all the site
classes, all of the states and

719
00:58:31.830 --> 00:58:33.970
territories of the United States.

720
00:58:33.970 --> 00:58:36.790
So there's a lot of data on this this
site.

721
00:58:36.810 --> 00:58:44.010
This is just three of 100 hundreds of
files.

722
00:58:45.210 --> 00:58:49.530
And really quick, if you happen to be
going to the 12th National Conference on

723
00:58:49.530 --> 00:58:54.690
Earthquake Engineering, interested in
hearing more about the US seismic design

724
00:58:54.990 --> 00:59:00.480
database is there's a short paper in that
conference and there'll be a presentation

725
00:59:01.380 --> 00:59:02.460
as well on that.

726
00:59:03.480 --> 00:59:09.030
So that data we publish it so that static
and people have access to it.

727
00:59:09.030 --> 00:59:12.810
But really it's sort of cumbersome to
deal with these large files that have

728
00:59:13.170 --> 00:59:19.680
values that cover all the 48 states and
have 600,000 points in them, large data

729
00:59:19.680 --> 00:59:26.250
files. So it's really this web service
like you do with current practice, 8716

730
00:59:26.790 --> 00:59:32.580
that you use or as I'll show in the next
slide, a more user friendly interface to

731
00:59:32.580 --> 00:59:38.280
this. But yes, yes, web service, the
inputs are basically latitude, longitude

732
00:59:38.460 --> 00:59:39.660
and site class.

733
00:59:40.260 --> 00:59:48.150
So the error really works is in a URL you
enter latitude longitude site class,

734
00:59:48.150 --> 00:59:52.760
also risk category because this will
return seismic design category and

735
00:59:52.800 --> 00:59:53.970
optional title.

736
00:59:53.970 --> 00:59:57.480
And this is an example of the response
that you get back, right?

737
00:59:57.630 --> 01:00:01.350
It's readable but not very user friendly.

738
01:00:01.350 --> 01:00:08.820
No, no plots because these Web services
are really intended to be an engine

739
01:00:08.820 --> 01:00:11.940
behind a more user friendly interface.

740
01:00:11.940 --> 01:00:17.190
So these provide all the values that you
need, in some cases, some deeper values

741
01:00:17.190 --> 01:00:21.090
or component values that you might not
interface.

742
01:00:21.660 --> 01:00:27.810
But something like this basic tool for
the 2020 NEHRP provisions would be

743
01:00:27.810 --> 01:00:33.780
something that most users would go
through to access these new design

744
01:00:33.800 --> 01:00:40.580
promotions. ASCE 7-22 Now some version of
this is as well, and then you enter

745
01:00:40.590 --> 01:00:45.320
latitude, longitude and site class and it
gives back these parameters like SMS and

746
01:00:45.520 --> 01:00:51.210
and one that we've been talking about as
well as some plots like multi period

747
01:00:51.210 --> 01:00:52.410
design spectrum.

748
01:00:52.680 --> 01:00:56.160
So a little bit more user friendly.

749
01:00:57.650 --> 01:01:05.050
Okay. And so here I'll just start to
close here by mentioning that a lot of

750
01:01:05.110 --> 01:01:11.020
what I've talked about is available
through this portal that we've created.

751
01:01:11.020 --> 01:01:18.520
So this address at the top, this digital
object identifier, is something that we

752
01:01:18.520 --> 01:01:19.540
don't change.

753
01:01:19.540 --> 01:01:24.040
And that's helpful because sometimes the
USGS Web addresses will change.

754
01:01:24.130 --> 01:01:28.480
It's not in our control, but this deal, I
will not change.

755
01:01:28.480 --> 01:01:34.410
That's what you'll find in the year 2020
NEHRP provision also in ASCE 7-22 and

756
01:01:34.420 --> 01:01:41.960
this. This deal brought you to a website
that we can make sure is up to date.

757
01:01:41.960 --> 01:01:48.530
And so for the 2020 NEHRP positions this
website gives, you example the tool, the

758
01:01:48.530 --> 01:01:53.570
web interface for getting at the ground
motion values so that this tool that we

759
01:01:53.570 --> 01:01:58.580
just looked at also gives you the Web
service link here.

760
01:01:58.930 --> 01:02:04.100
It gives you a link to maps which are
really in there are some maps in the

761
01:02:04.580 --> 01:02:10.910
provisions just for SMEs and some one for
default site classes, some additional

762
01:02:10.910 --> 01:02:14.120
maps that we're interested in adding.

763
01:02:14.120 --> 01:02:19.370
We started to you will continue that and
then the data itself that US seismic

764
01:02:19.370 --> 01:02:25.190
design geo database has a permanent
location as well.

765
01:02:27.830 --> 01:02:27.940
Well.

766
01:02:28.360 --> 01:02:30.570
Thanks for listening.

767
01:02:30.610 --> 01:02:32.260
Here's my contact info.

768
01:02:32.290 --> 01:02:35.290
I do hope we have a little time for
questions at the end, but now I'll turn

769
01:02:35.290 --> 01:02:37.330
it over to C.B.

770
01:02:37.330 --> 01:02:39.640
Crouse and I will stop sharing.

771
01:02:40.900 --> 01:02:44.400
So, while C.B. is preparing his slides to
let everyone know.

772
01:02:44.410 --> 01:02:46.900
We will try to answer all the questions
in the end.

773
01:02:46.960 --> 01:02:49.630
So please make sure to type in your
questions now.

774
01:02:49.660 --> 01:02:50.230
Thank you.

775
01:02:52.930 --> 01:02:54.370
Thank you. Charlie.

776
01:02:54.400 --> 01:03:00.950
Nico. You can all see my screen I hope?

777
01:03:02.030 --> 01:03:02.990
Yes, we can. Yep.

778
01:03:03.580 --> 01:03:07.850
Okay. Well, my presentation is really a
follow on to Charlie's, and I'll be

779
01:03:07.850 --> 01:03:13.520
covering three additional provisions in
ground motion that he didn't cover.

780
01:03:16.830 --> 01:03:21.060
And my slides are not advancing for some
reason.

781
01:03:30.610 --> 01:03:32.950
Excuse me. I'm not sure what's happening.

782
01:03:45.560 --> 01:03:47.170
Jq. I don't know what's going on.

783
01:03:47.180 --> 01:03:49.190
It's. The slides aren't advancing.

784
01:03:49.550 --> 01:03:50.960
Something's happened.

785
01:03:51.140 --> 01:03:54.020
Yeah. So do you want to stop sharing and
share?

786
01:03:54.050 --> 01:04:00.100
Sometimes I don't work. Okay.

787
01:04:01.180 --> 01:04:02.570
Let's try it again.

788
01:04:11.180 --> 01:04:12.770
Let's see if they advance.

789
01:04:15.850 --> 01:04:17.530
No, they're not advancing.

790
01:04:22.990 --> 01:04:26.590
So how about let me open up share from my
side?

791
01:04:33.160 --> 01:04:33.970
Oh, wait a minute.

792
01:04:35.560 --> 01:04:37.330
For some reason, I was using a down here.

793
01:04:37.330 --> 01:04:38.620
I'll have to use my.

794
01:04:39.750 --> 01:04:44.910
By curfew. And now, unless you took over
the screen, I can advance the slides, it

795
01:04:44.910 --> 01:04:45.570
looks like.

796
01:04:45.750 --> 01:04:48.450
Yeah. Please go ahead. See, we can see
the cover, too.

797
01:04:48.450 --> 01:04:48.680
Yeah.

798
01:04:49.260 --> 01:04:50.760
I don't know what happened down here.

799
01:04:50.760 --> 01:04:55.830
I was working when I was doing this
before OC So like I said, this is really

800
01:04:55.830 --> 01:04:58.920
a follow up to Charlie's presentation.

801
01:04:58.920 --> 01:05:03.870
And the first thing I'm going to talk
about is the revisions to the maximum

802
01:05:03.870 --> 01:05:09.720
considered earthquake geometric mean
ground acceleration and Section 21.5.

803
01:05:10.380 --> 01:05:14.130
That's going to be followed by revisions
to the vertical ground motion in section

804
01:05:14.130 --> 01:05:19.680
11.9. And lastly, the new provisions for
determining the site class and

805
01:05:19.680 --> 01:05:24.720
corresponding response spectrum when
shear wave velocity measurements are not

806
01:05:24.720 --> 01:05:26.010
made at a site.

807
01:05:27.620 --> 01:05:31.760
So first the revisions to the GP ground
acceleration.

808
01:05:32.400 --> 01:05:40.340
Recall that in section 11 .8.3 in RC 716,
this PGA was defined

809
01:05:40.340 --> 01:05:46.940
by the simple equation where the F sub
PGA was a site coefficient and PGA was

810
01:05:46.940 --> 01:05:53.990
the map PGA for an average shear velocity
of 760 meters per second, and in section

811
01:05:53.990 --> 01:06:01.760
21.5.2 the deterministic lower limit, MSI
PGA was set at 0.5 times

812
01:06:01.760 --> 01:06:04.280
the site coefficient FS of PGA.

813
01:06:07.080 --> 01:06:12.840
Now in ASCE 7-22 PSI coefficients were
eliminated due to the switch to the multi

814
01:06:12.840 --> 01:06:17.100
period response vector for the eight PSI
classes, as Charlie had mentioned.

815
01:06:18.090 --> 01:06:25.590
And this meant that the PGA in section 11
.8.3 is now obtained directly

816
01:06:25.590 --> 01:06:33.360
from the USGS seismic design database or
another more user friendly, such as

817
01:06:33.360 --> 01:06:38.490
the ASCE 7 Data Access Tool or the BSSC
tool.

818
01:06:40.580 --> 01:06:46.490
And in Chapter 21, the deterministic
lower limit of this parameter is provided

819
01:06:46.490 --> 01:06:52.100
in the bottom row of table 21.2, dash one
for the applicable site class.

820
01:06:52.100 --> 01:06:56.300
And this is the bottom row of the table
that Charlie presented in his

821
01:06:56.300 --> 01:07:03.270
presentation. There were other revisions
to Section

822
01:07:03.270 --> 01:07:10.200
21.5 and in particular how the
deterministic PGA was determined.

823
01:07:12.420 --> 01:07:17.730
The first change was notational, where
the words characteristic earthquakes were

824
01:07:17.730 --> 01:07:19.580
replaced with scenario earthquakes.

825
01:07:19.590 --> 01:07:26.730
As Nico mentioned in his presentation,
and the procedure is identical to the one

826
01:07:26.730 --> 01:07:30.750
Nico presented for the multi period
response vector and namely that the

827
01:07:30.750 --> 01:07:35.160
scenario earthquakes are determined from
the disaggregation of the probabilistic

828
01:07:35.430 --> 01:07:40.410
mce PGA with a 2% and 50 year exceedance
probability.

829
01:07:41.610 --> 01:07:45.990
So from this the aggregation one would
obtain the mean magnitude and mean

830
01:07:45.990 --> 01:07:50.400
rupture distance for each fault, and
these parameters would define the

831
01:07:50.400 --> 01:07:52.230
scenario earthquake for the fault.

832
01:07:53.550 --> 01:07:58.620
Then, as Nico explained, those scenarios
contributing less than 10% of the largest

833
01:07:58.620 --> 01:08:00.510
contributor are ignored.

834
01:08:01.700 --> 01:08:08.840
So again, another example, suppose we
have fault X that has a 75% contribution

835
01:08:08.840 --> 01:08:14.660
and hence it's the largest contributor
and fault Y has a 20% contribution.

836
01:08:14.660 --> 01:08:20.510
So it's included because the ratio of 20
divided by 75 is greater than 10%.

837
01:08:21.350 --> 01:08:26.720
However, followed see is ignored because
it's 5% contribution, it's less than 10%

838
01:08:26.720 --> 01:08:27.980
of 75.

839
01:08:32.370 --> 01:08:39.510
The slide is a reminder that in section
20 1.5.3, the determination of the

840
01:08:40.320 --> 01:08:46.230
PGA is similar in both ASCE 7-16 and the
ASCE 7-22 standards.

841
01:08:46.590 --> 01:08:50.670
And that is, you take the law of the
probabilistic and deterministic PGA

842
01:08:50.670 --> 01:08:57.060
values, but note that the resulting PGA
must be greater than or equal to 80% of

843
01:08:57.060 --> 01:09:03.210
the PGA from the USGS Seismic Design Geo
database or another more user friendly

844
01:09:03.210 --> 01:09:04.650
data access tool.

845
01:09:07.610 --> 01:09:12.470
Now for the revisions to the vertical
ground motion provisions in Section 11.9

846
01:09:13.010 --> 01:09:20.660
recall they were first introduced in ASCE
7-16 as the parameter sub A and V, and

847
01:09:20.660 --> 01:09:24.320
that's the symbol for the vertical
component response spectral acceleration.

848
01:09:25.820 --> 01:09:27.110
This provision was.

849
01:09:27.110 --> 01:09:27.920
Optional.

850
01:09:30.460 --> 01:09:35.920
The spectrum was defined by equations for
four specific vertical natural period

851
01:09:35.920 --> 01:09:42.350
ranges. And it was derived from vertical
to horizontal component response spectral

852
01:09:42.350 --> 01:09:46.010
ratios applied to the MCI response
spectrum.

853
01:09:48.220 --> 01:09:52.900
There is one limitation and that is there
is no equation to define the vertical

854
01:09:52.900 --> 01:09:55.810
component spectrum for periods greater
than 2 seconds.

855
01:09:56.350 --> 01:10:00.640
Rather, a state specific study was
required to determine the spectrum for

856
01:10:00.640 --> 01:10:05.140
those periods, and there was a major
oversight.

857
01:10:06.550 --> 01:10:11.770
The horizontal component and the voltage
ratio was the geometric mean, whereas the

858
01:10:11.780 --> 01:10:17.140
MCI response spectrum acceleration was
for the direction of maximum shaking.

859
01:10:19.970 --> 01:10:23.780
So in the update, this limitation and
oversight were corrected.

860
01:10:24.920 --> 01:10:29.450
The limitation was corrected by including
an equation for periods greater than 2

861
01:10:29.450 --> 01:10:35.730
seconds. And the oversight was corrected
by dividing the response spectrum by

862
01:10:35.730 --> 01:10:41.070
period dependent factors f sub md to
convert this spectrum to the geometric

863
01:10:41.070 --> 01:10:47.130
mean. Now these factors are given by
equations for three specific period

864
01:10:47.130 --> 01:10:52.800
ranges. Like Nico said, they were based
on tabular values of these factors in the

865
01:10:52.800 --> 01:10:57.870
2014 Shanahan Baker publication in the
Earthquake Spectra Journal.

866
01:10:59.100 --> 01:11:03.930
Also, the vertical coefficient C sub V
was revised to accommodate the nine new

867
01:11:03.930 --> 01:11:05.070
CI classes.

868
01:11:06.270 --> 01:11:14.040
The new CCP values are now found in table
11 .9-1 and they now depend on SE sub MZ

869
01:11:14.040 --> 01:11:16.020
rather than sub s.

870
01:11:17.970 --> 01:11:23.130
So here is a plot comparing the vertical
and horizontal component response spectra

871
01:11:23.130 --> 01:11:26.310
for a CI Class D site in Irvine,
California.

872
01:11:27.300 --> 01:11:31.920
You see that the vertical component
spectrum is greater than the horizontal

873
01:11:31.920 --> 01:11:36.750
component at short periods, but the
horizontal component spectrum is much

874
01:11:36.750 --> 01:11:38.580
greater at the longer periods.

875
01:11:38.580 --> 01:11:43.170
And this plot is typical for sites near
active faults.

876
01:11:47.850 --> 01:11:52.260
Lastly, I'll discuss the provisions for
determining site class and the associated

877
01:11:52.440 --> 01:11:57.000
CPR response spectrum when Stairway
Velocity data are not available at a

878
01:11:57.000 --> 01:12:03.460
site. So recall in section 20.3 and I
716.

879
01:12:03.480 --> 01:12:08.310
The site class is determined from either
the average share velocity in the upper

880
01:12:08.310 --> 01:12:15.030
100 feet, the average blow count over
this depth or the average shear strength

881
01:12:16.200 --> 01:12:20.190
and the ranges of these parameters for
the different site classes were provided

882
01:12:20.190 --> 01:12:22.800
in table 20 .3-1.

883
01:12:24.860 --> 01:12:32.420
However, an ASCE 7-22, the corresponding
table 20.2-1 only includes average shear

884
01:12:32.420 --> 01:12:35.330
weight. Velocity is the classification
criterion.

885
01:12:35.630 --> 01:12:40.490
The blow count and untrained shear
strength criteria have eliminated, as

886
01:12:40.490 --> 01:12:41.540
Charlie mentioned.

887
01:12:43.520 --> 01:12:46.880
So the question is, why were these
revisions made?

888
01:12:48.270 --> 01:12:52.650
First, the average share velocity was
considered a better indicator of sight

889
01:12:52.650 --> 01:12:54.000
response effects.

890
01:12:55.280 --> 01:12:59.630
Secondly, the blow count and shear
strength ranges were outdated by about 30

891
01:12:59.630 --> 01:13:04.520
years, and even back then they were based
mostly on judgment with no solid

892
01:13:04.520 --> 01:13:05.750
technical basis.

893
01:13:07.160 --> 01:13:10.940
And finally, the revision was made to
encourage the use of sure wave velocity

894
01:13:10.940 --> 01:13:14.090
measurements for site classification
purposes.

895
01:13:15.590 --> 01:13:19.970
However, it was acknowledged there will
be projects where the service is not

896
01:13:19.970 --> 01:13:25.760
measured and in those cases applicable
correlations between shear wave velocity

897
01:13:25.760 --> 01:13:30.390
and other parameters say such as blow
count or competitor.

898
01:13:30.430 --> 01:13:35.690
Amateur test data are to be used to
obtain the sheer weight velocity profile.

899
01:13:35.870 --> 01:13:40.700
Once that profile's obtained, then one
computes the average shear wave velocity

900
01:13:40.700 --> 01:13:47.420
from that profile and determine the site
classes from that value 1.3 times that

901
01:13:47.420 --> 01:13:50.660
value and that value divided by 1.3.

902
01:13:51.560 --> 01:13:55.850
Then you select the most critical site
class at each period, which is the one

903
01:13:55.850 --> 01:14:00.980
that results in the largest MCE response
spectral acceleration.

904
01:14:03.680 --> 01:14:07.460
So here's a hypothetical example
illustrating the procedure.

905
01:14:07.550 --> 01:14:12.090
Let's take the same Irvine site that's
been used and assume the stairway

906
01:14:12.140 --> 01:14:16.970
velocity profile was constructed from a
correlation with another sole parameter.

907
01:14:18.400 --> 01:14:23.440
And let's say the soil profile of an
average shear weight velocity of 850 feet

908
01:14:23.440 --> 01:14:25.480
per second, which puts the sign in sight.

909
01:14:25.480 --> 01:14:30.130
Class D 1.3 times this velocity would put
it in sight.

910
01:14:30.130 --> 01:14:35.580
Class C, D, and this velocity divided by
1.3 would put it in sight.

911
01:14:35.590 --> 01:14:43.570
Class D then the MCI response spectrum
from all three site classes

912
01:14:43.570 --> 01:14:46.300
is computed, and this plot shows the
results.

913
01:14:46.720 --> 01:14:51.970
Basically, the envelope is taken as the
final MCI response spectrum.

914
01:14:52.860 --> 01:14:57.120
And this particular example shows the
possible overly conservative spectrum

915
01:14:57.300 --> 01:15:02.040
that would be obtained if the actual site
class turned out to be CD.

916
01:15:02.550 --> 01:15:08.220
Note how the percent difference increases
from 0.5 seconds where the spectral

917
01:15:08.220 --> 01:15:14.010
acceleration is 20% greater than the CD
spectral acceleration and at 2 seconds

918
01:15:14.010 --> 01:15:16.800
where the percent increase is almost
100%.

919
01:15:17.130 --> 01:15:23.640
So the lesson is, is if you think that
there's a high likelihood you're in site

920
01:15:23.640 --> 01:15:29.070
class CD based on some information you
have, say, at nearby sites, then it

921
01:15:29.070 --> 01:15:33.750
really pays to do a share way velocity
measurement, particularly if the

922
01:15:33.750 --> 01:15:39.300
structural engineer tells you that his
building period is 0.5 seconds or

923
01:15:39.300 --> 01:15:44.780
greater. And that concludes my
presentation.

924
01:15:44.790 --> 01:15:47.490
Thank you for your patience. Thank you
for your attention.

925
01:15:49.370 --> 01:15:51.770
Thank you. CB, Nico and Charlie.

926
01:15:52.820 --> 01:15:55.760
CB, if you could stop sharing your
screen.

927
01:15:55.850 --> 01:15:58.970
I think we can go to a Q&A session.

928
01:16:01.640 --> 01:16:06.860
So we do get a lot of questions before I
read out the questions to our panel.

929
01:16:07.400 --> 01:16:10.980
I want to let everyone know we've got
about 20 questions.

930
01:16:11.000 --> 01:16:14.330
Some of those questions has been
answered, expanded for those.

931
01:16:14.420 --> 01:16:16.920
Know where to get the PowerPoint.

932
01:16:16.940 --> 01:16:20.000
How to get a certificate, where to
download, etc.

933
01:16:20.030 --> 01:16:21.150
has to be answered.

934
01:16:21.170 --> 01:16:25.310
Also I saw Nico has been answering some
of those questions, you know, like where

935
01:16:25.310 --> 01:16:27.460
to download the data, etc.

936
01:16:27.470 --> 01:16:33.380
So make sure to check some of those
answered questions in the chat box.

937
01:16:33.530 --> 01:16:38.960
So I'm going to read out the other
answers questions to to our panels.

938
01:16:39.320 --> 01:16:41.030
I will start from the very beginning.

939
01:16:42.140 --> 01:16:46.990
So I think today Nico, CB, I think
anybody can answer this question.

940
01:16:47.000 --> 01:16:48.830
We have about eight questions.

941
01:16:49.250 --> 01:16:56.330
So the first one is what geographic areas
is captured in the US database?

942
01:16:57.470 --> 01:17:00.710
Also, I will combine this with another
question if the question.

943
01:17:00.740 --> 01:17:06.620
The second question is how do we get the
data for locations that is outside the US

944
01:17:07.400 --> 01:17:08.120
database?

945
01:17:14.970 --> 01:17:16.680
Well, I'll start.

946
01:17:18.960 --> 01:17:26.430
So for the first question, the USGS
database that really just covers the US

947
01:17:26.430 --> 01:17:30.030
and its territories. So it's the 50
states.

948
01:17:30.390 --> 01:17:31.110
And.

949
01:17:31.620 --> 01:17:37.230
Puerto Rico, US Virgin Islands, Guam,
Northern Mariana Islands and American

950
01:17:37.230 --> 01:17:44.010
Samoa. One footnote to that is what
Charlie mentioned, which was

951
01:17:45.390 --> 01:17:46.850
calculating multi periods.

952
01:17:46.900 --> 01:17:53.880
Spectra within the US directly is
something that we only could do for the

953
01:17:53.880 --> 01:17:56.670
48 states for the US.

954
01:17:57.410 --> 01:18:01.960
Now. Yes, it could do it for Hawaii
because we since the 2020 NEHRP

955
01:18:02.090 --> 01:18:08.090
provisions, we've had an update of the
USGS hazard model for Hawaii, for the

956
01:18:08.090 --> 01:18:12.410
other states and territories where we
could do that.

957
01:18:12.820 --> 01:18:19.100
That's our Charlie reference, this
procedure to take a short period in 1/2

958
01:18:19.100 --> 01:18:26.060
value and sort of interpolate extrapolate
those to the multi period spectrum.

959
01:18:28.580 --> 01:18:30.110
It is, Charlie, I'm sure.

960
01:18:31.490 --> 01:18:35.890
Four locations outside this covered by
the US.

961
01:18:35.900 --> 01:18:38.300
She has for these multi period spectra.

962
01:18:38.330 --> 01:18:41.830
I'll just make one note that right now
it's probably tough.

963
01:18:41.840 --> 01:18:46.190
You've got to do site specific and site
specific with motion models that would

964
01:18:46.190 --> 01:18:51.440
let you get lots of different spectral
periods and do different site classes,

965
01:18:51.440 --> 01:18:53.390
not just a reference site class.

966
01:18:55.100 --> 01:18:59.780
We'll say there's a project that we're
working on with Department of Defense and

967
01:18:59.780 --> 01:19:07.370
Department of State to use the global
earthquake model from model.

968
01:19:07.370 --> 01:19:15.110
And it's a compute these these design
spectra from their ground motion

969
01:19:15.110 --> 01:19:19.790
models now to get to multi period
internationally is still it's a four year

970
01:19:19.790 --> 01:19:22.250
project and that's the fourth year.

971
01:19:22.520 --> 01:19:28.280
So that is still, I guess, three, three
years out from from now.

972
01:19:29.810 --> 01:19:33.950
You know, you also touch on one of the
questions about the UFC, but they will

973
01:19:34.100 --> 01:19:35.230
return that later on.

974
01:19:35.330 --> 01:19:42.170
So the next question is about does HRC
something new to require you to select

975
01:19:42.170 --> 01:19:48.890
the response for a specific period rather
than recalculate a two point spectrum?

976
01:19:54.110 --> 01:19:55.400
So. So. So. Try to do it.

977
01:19:55.990 --> 01:20:03.830
Do you want to answer this one? Tardy,
muted if you

978
01:20:03.830 --> 01:20:05.330
are speaking.

979
01:20:14.200 --> 01:20:20.920
Now. I didn't hear from Charlie. Hey,
Nico, do you want to answer this one?

980
01:20:22.470 --> 01:20:24.660
He give a crack at what?

981
01:20:24.660 --> 01:20:28.380
We're answering the other questions, I
will double check it because I know

982
01:20:28.380 --> 01:20:33.510
through the process this was a topic that
went back and forth a little bit while

983
01:20:33.510 --> 01:20:35.510
the new provisions were being developed.

984
01:20:35.520 --> 01:20:41.310
But I think we ended up with saying use
the multi period spectrum unless you

985
01:20:41.310 --> 01:20:48.810
don't have it, which in the US and its
territories you do have it.

986
01:20:48.810 --> 01:20:52.650
So you really are pushed to use that
multi period spectrum.

987
01:20:52.770 --> 01:20:58.320
The two period spectrum is really there
because it's recognized that people use

988
01:20:59.130 --> 01:21:05.460
provisions 87 overseas and they really
might not have a multi period spectrum.

989
01:21:07.150 --> 01:21:09.760
So Charlie, CB do you want to chime in as
well?

990
01:21:09.790 --> 01:21:16.600
Yeah. I'll just read from ASCE 7-22
Section 11

991
01:21:16.600 --> 01:21:21.520
.4.5 says Where a design response
spectrum is required by the standard, the

992
01:21:21.520 --> 01:21:25.090
design response spectrum shall be
determined in accordance with the

993
01:21:25.090 --> 01:21:31.180
requirements of section 11 .4.5.1, which
is the multi period design response

994
01:21:31.180 --> 01:21:35.290
spectrum. However, there were two
exceptions that were noted.

995
01:21:35.500 --> 01:21:40.150
First exception was where a site specific
ground motion analysis is performed in

996
01:21:40.150 --> 01:21:43.000
accordance with Section 11 .4.7.

997
01:21:43.660 --> 01:21:47.770
The design response spectrum shall be
determined in accordance with Section

998
01:21:47.770 --> 01:21:54.680
21.3, exception to said where values of
the multi period 5% band C.R.

999
01:21:54.790 --> 01:22:00.940
response spectrum are not available from
the USGS seismic design database or like

1000
01:22:01.000 --> 01:22:02.860
the ASCE 7 lookup tool.

1001
01:22:03.580 --> 01:22:07.300
The design response spectrum shall be
permitted to be determined in accordance

1002
01:22:07.300 --> 01:22:13.420
with 11 .4.5.2, which is the two period
design response spectrum concept.

1003
01:22:15.730 --> 01:22:21.370
Yep. That sounds good, Charlie.

1004
01:22:21.370 --> 01:22:25.960
If you if you if you don't have all the
things and we're moving into the next

1005
01:22:25.960 --> 01:22:30.700
question. I hear nothing.

1006
01:22:31.000 --> 01:22:34.360
The next one is, you know, with a
multiple response factor.

1007
01:22:34.870 --> 01:22:40.600
Does the return period of of the
acceleration at each period vary?

1008
01:22:49.300 --> 01:22:50.170
Yes.

1009
01:22:53.030 --> 01:22:54.150
Making sure.

1010
01:22:56.510 --> 01:22:57.740
Yes. Yeah.

1011
01:22:57.740 --> 01:23:00.410
So it was from.

1012
01:23:01.460 --> 01:23:09.410
Yeah. It does vary with spectral period
and also would actually vary with site

1013
01:23:09.710 --> 01:23:17.650
class. But this isn't really new because
since the misuse of ah motion

1014
01:23:17.660 --> 01:23:23.660
is their risk targeted, the, the return
period, the hazard return period already

1015
01:23:23.660 --> 01:23:28.160
varied spatially even in ASCE 7-16.

1016
01:23:28.670 --> 01:23:36.170
So the, the risk targets are all uniform
except where deterministic controls the

1017
01:23:36.170 --> 01:23:40.820
risk target is the same everywhere
spatially it's the same across the

1018
01:23:40.820 --> 01:23:46.370
different spectral periods and it's the
same across the the cycle, but not the

1019
01:23:46.550 --> 01:23:49.520
uniform or hazard return period.

1020
01:23:53.440 --> 01:23:55.680
Okay. Again participate.

1021
01:23:55.680 --> 01:23:57.580
If you guys want to try me, let me know.

1022
01:23:57.600 --> 01:23:59.850
Otherwise, I will keep moving to the next
question.

1023
01:24:01.440 --> 01:24:06.210
So the next question is why the
difference in spectral acceleration

1024
01:24:06.210 --> 01:24:10.080
between t equal to 0/2 and the PJ.

1025
01:24:14.370 --> 01:24:15.460
Can you repeat that?

1026
01:24:15.480 --> 01:24:17.580
Which period were we talking about?

1027
01:24:17.580 --> 01:24:17.970
What was the.

1028
01:24:17.970 --> 01:24:24.060
Period between t equal to zero 0/2 and
PJ?

1029
01:24:24.920 --> 01:24:27.620
The peak quantum ground acceleration?

1030
01:24:28.130 --> 01:24:34.580
Well, the peak ground acceleration,
that's is the geometric mean.

1031
01:24:34.580 --> 01:24:41.900
I believe that's to be used in primarily
chapter or a section 11 .8.3.

1032
01:24:46.420 --> 01:24:48.160
The PGA subsidy.

1033
01:24:50.690 --> 01:24:54.380
If that's that's that would be the reason
for the difference.

1034
01:24:56.230 --> 01:25:03.370
Okay. So the next question I think CB
answered this one in your presentation is

1035
01:25:03.370 --> 01:25:09.460
asking is the vertical response affected
unless you have something to add?

1036
01:25:09.880 --> 01:25:11.770
But I think you answer this question in
your presentation.

1037
01:25:15.610 --> 01:25:19.360
The question is about the vertical
response spectrum.

1038
01:25:19.630 --> 01:25:21.610
What is what is the question?

1039
01:25:22.360 --> 01:25:25.270
Is the vertical response affected?

1040
01:25:28.410 --> 01:25:29.760
Is the fact that I don't.

1041
01:25:33.010 --> 01:25:38.200
The vertical response is based on the MCE
response.

1042
01:25:41.100 --> 01:25:47.550
So we had we had to correct some things,
as I mentioned in my presentation.

1043
01:25:47.550 --> 01:25:55.230
But the it's all based on primarily the V
over ratios that are multiplied

1044
01:25:55.230 --> 01:26:03.030
by the MCI response spectrum with the
correction factors F sub MD which

1045
01:26:03.300 --> 01:26:06.150
were not included in ASCE 7-16.

1046
01:26:06.150 --> 01:26:10.620
And that was the oversight that needed to
be corrected, as I mentioned.

1047
01:26:12.780 --> 01:26:17.220
Sounds good. So the next two questions
are very similar in a similar manner.

1048
01:26:17.220 --> 01:26:24.300
So it's asking in a sense, the RC 72 has
not been adopted by the code, which has

1049
01:26:24.300 --> 01:26:26.010
not been in effect.

1050
01:26:26.550 --> 01:26:32.190
The question is, can we use the updated
the sizing parameters as of this SFD one

1051
01:26:32.190 --> 01:26:38.370
for the design while the bidding will be
designed in accordance to the ASCE 7-16.

1052
01:26:39.120 --> 01:26:43.500
Similarly, I think this is from DOD or
Nafdac asking though right now they are

1053
01:26:44.080 --> 01:26:51.750
still using the UFC 3-30101 for the
structure engineer, which requires the

1054
01:26:51.750 --> 01:26:53.640
IBC 2018.

1055
01:26:54.480 --> 01:26:59.430
So the the new Mod period response
spectrum won't be updated for that UFC

1056
01:26:59.430 --> 01:27:04.020
for a while. What can they do in the
meantime to ensure the designs are

1057
01:27:04.020 --> 01:27:05.880
adequately adequate?

1058
01:27:05.910 --> 01:27:08.070
No, you know, knowing what we know now.

1059
01:27:08.940 --> 01:27:09.990
So, Jake.

1060
01:27:11.220 --> 01:27:12.720
Jake, you. This is Charlie.

1061
01:27:13.860 --> 01:27:15.150
I'm sorry. I lost.

1062
01:27:15.150 --> 01:27:17.520
I was lost there. I'll be I'll let me.

1063
01:27:18.110 --> 01:27:22.230
You know, these are minimum requirements
an engineer can always use more.

1064
01:27:22.230 --> 01:27:27.090
So if you're if you take 7-22 and 7-16
and you choose to use T2 because it's

1065
01:27:27.090 --> 01:27:30.300
more conservative, nothing will hinder
that.

1066
01:27:30.330 --> 01:27:34.410
If you went to a building department,
however, with lower ground motion, you're

1067
01:27:34.410 --> 01:27:37.590
going to have to get the building
department or the authority or the or in

1068
01:27:37.590 --> 01:27:41.430
this case, the military to agree to that.

1069
01:27:41.880 --> 01:27:46.740
But nothing would preclude you from using
something that is an envelope of the two.

1070
01:27:48.430 --> 01:27:56.320
So what I have suggested on some projects
is to

1071
01:27:56.320 --> 01:28:02.140
use the multi period response vector as a
proxy for site specific spectrum

1072
01:28:02.140 --> 01:28:10.120
according to Chapter 21 and let that
serve as the site

1073
01:28:10.120 --> 01:28:11.230
specific spectrum.

1074
01:28:11.230 --> 01:28:17.710
But it would have to be checked against
the USGS 80% minimum requirement and say

1075
01:28:17.740 --> 01:28:20.740
ASCE 7-16, Chapter 21.

1076
01:28:24.190 --> 01:28:25.690
Okay. That sounds good.

1077
01:28:26.140 --> 01:28:31.060
The next question is, did the scaling
scaling procedure also change?

1078
01:28:31.720 --> 01:28:33.160
How about the near fort?

1079
01:28:33.190 --> 01:28:37.090
Near fort motions and the scaling
procedures for them?

1080
01:28:42.620 --> 01:28:47.930
Well, this is all built into the ground
motion models that the USGS is using.

1081
01:28:47.930 --> 01:28:52.730
Near field effects are are built into
those models.

1082
01:28:52.730 --> 01:28:56.780
So Nico, did you want to add anything to
that?

1083
01:29:01.050 --> 01:29:02.270
Just reinforce that.

1084
01:29:02.270 --> 01:29:09.960
I mean, just with the scanning procedure
might be referring to scaling for

1085
01:29:09.990 --> 01:29:13.590
promotion time series if you're doing
response history analysis.

1086
01:29:13.980 --> 01:29:14.610
Oh.

1087
01:29:16.170 --> 01:29:22.630
I mean, if that's the case, this work is
really affecting the target spectra, the

1088
01:29:22.650 --> 01:29:23.300
mix of.

1089
01:29:23.310 --> 01:29:23.910
Our.

1090
01:29:25.290 --> 01:29:31.260
Spectra, but but not changing the
procedures by which you would get

1091
01:29:31.560 --> 01:29:38.670
promotion time series that match that,
that spectrum and therefore also no

1092
01:29:38.670 --> 01:29:44.880
changes in requirements of how many near
fall promotions you might have.

1093
01:29:45.750 --> 01:29:49.620
Chapter 16 and chapter 16 was updated
for.

1094
01:29:51.170 --> 01:29:58.070
See 7-16 2015, but it was not updated
this cycle much.

1095
01:30:00.130 --> 01:30:02.950
So are a little bit out of time.

1096
01:30:03.190 --> 01:30:05.380
It's 231. I think we have two more
questions.

1097
01:30:05.530 --> 01:30:08.170
We'll try to answer all of them before we
close this out.

1098
01:30:08.170 --> 01:30:10.950
So bear with us for another minute or
two.

1099
01:30:10.960 --> 01:30:17.560
So the next part is, you know, what
should we expect for the AC 41?

1100
01:30:21.880 --> 01:30:28.450
We are we are only addressing ASCE 7, but
the folks that are working on 41 are, I

1101
01:30:28.450 --> 01:30:32.260
think, struggling with how to incorporate
this into 41.

1102
01:30:38.070 --> 01:30:39.000
Not there yet.

1103
01:30:39.480 --> 01:30:45.900
Not there yet. So the last question, I
think all we can answer that is asking

1104
01:30:45.900 --> 01:30:52.440
Nico. You know, you mentioned the project
17 also or Elektra in 2019.

1105
01:30:52.440 --> 01:30:54.630
You mentioned the project project oh
seven.

1106
01:30:54.810 --> 01:30:57.900
Can you share what are those projects?

1107
01:30:59.700 --> 01:31:01.710
Just give an overview.

1108
01:31:02.020 --> 01:31:06.150
What's difference between oh 717 without
this project?

1109
01:31:06.720 --> 01:31:09.090
Okay. Yeah, I'll do a quick answer.

1110
01:31:09.120 --> 01:31:15.250
Let's say there's a webinar where with
Ron Hamburger Zion.

1111
01:31:15.690 --> 01:31:18.030
If you're interested, that's a good one
to watch.

1112
01:31:18.330 --> 01:31:26.070
I could also try to put links to reports
from the final report from Project 17,

1113
01:31:26.070 --> 01:31:33.240
that's on the PSC website that there's
something comparable for Project seven.

1114
01:31:33.240 --> 01:31:40.200
But in case there is Project 97 in the
mid 1990s, that led to

1115
01:31:40.890 --> 01:31:47.040
before my time, but not entirely that led
to the USB hazard model really being

1116
01:31:47.040 --> 01:31:51.540
directly used to produce maps for the neo
provisions.

1117
01:31:51.720 --> 01:31:58.260
87 project oh seven was just ten years
later and say, okay, let's look back at

1118
01:31:58.260 --> 01:32:02.490
what we did, see if there's any changes
that we want to make.

1119
01:32:02.520 --> 01:32:08.940
We made some changes like the risk
targeted promotions, for example, the

1120
01:32:08.940 --> 01:32:16.230
maximum direction scale factors, and then
Project 17 in 2017, same thing, revisit

1121
01:32:16.230 --> 01:32:20.280
what was done ten years previously, see
kind of what changes.

1122
01:32:20.280 --> 01:32:25.590
And those are changes for if you
categorize it into four changes that I

1123
01:32:25.590 --> 01:32:28.770
showed on my slide from Project 17.

1124
01:32:29.550 --> 01:32:31.020
So I did share the link.

1125
01:32:31.100 --> 01:32:35.650
I'm not sure I share the link where you
can listen to the recording on the May

1126
01:32:35.650 --> 01:32:37.650
19th webinar by Raw Hamburger.

1127
01:32:37.740 --> 01:32:44.090
And so that's risen to give you an
overview how the internal the US system

1128
01:32:44.100 --> 01:32:46.740
has been developed in the past 30 years.

1129
01:32:47.460 --> 01:32:50.250
Even if we do have one more question,
Charlie, this for you today.

1130
01:32:51.150 --> 01:32:55.170
So the question is made of multiple may
the multi period response factor

1131
01:32:55.170 --> 01:33:01.200
underestimate the demand for periods for
shorter periods where the spectrum is

1132
01:33:01.200 --> 01:33:06.720
flatter, the periods where equivalent
displacement is not valid.

1133
01:33:09.430 --> 01:33:15.400
Um, I'm not sure I understand the
question, but if it's a question about in

1134
01:33:15.400 --> 01:33:18.760
the Western U.S., we hope the spectra are
accurate and they're not going to predict

1135
01:33:18.760 --> 01:33:20.830
anything in the in the east.

1136
01:33:20.830 --> 01:33:24.310
As I was central and eastern U.S., I was
pointing out that the spectrum peaks at

1137
01:33:24.310 --> 01:33:30.460
shorter periods. If that's the question
they the coefficients required for

1138
01:33:30.460 --> 01:33:36.700
design, SDS, SD one are fine for building
design but and the response and there is

1139
01:33:36.700 --> 01:33:40.300
a multi period spectrum available.

1140
01:33:40.300 --> 01:33:45.400
So you have the spectrum available which
would indicate much more shaking at

1141
01:33:45.670 --> 01:33:51.130
shorter periods, say ten and 20 hertz
that could be used using in a multi

1142
01:33:51.130 --> 01:33:57.130
period response spectrum sense where the
coefficients are underestimating that

1143
01:33:57.130 --> 01:33:59.080
spectrum. I can't think of I'd be on the
case.

1144
01:33:59.080 --> 01:34:03.040
I think the question might be addressing
central and eastern U.S., I'm not sure.

1145
01:34:04.660 --> 01:34:06.040
Okay. Thank you, Charlie.

1146
01:34:06.040 --> 01:34:11.140
I think if you are 5 minutes beyond your
time, I want to take the time to thank

1147
01:34:11.140 --> 01:34:16.840
our all our speakers again for being with
us and also thank our other attendees who

1148
01:34:16.840 --> 01:34:19.870
are streaming us to listen to this
webinar.

1149
01:34:20.170 --> 01:34:25.450
As I said earlier, you can check out the
other webinars in this series through the

1150
01:34:25.470 --> 01:34:26.680
PS website.

1151
01:34:26.710 --> 01:34:30.490
Also, the recording for today's webinar
will be posted on that website.

1152
01:34:31.060 --> 01:34:35.140
With that I want to thank again for our
speakers today and I will conclude

1153
01:34:35.140 --> 01:34:38.380
today's webinar. Thank you and I'm with
you today.