Structural Engineering: 2007-11-18

Saturday, November 24, 2007

RE: Steel SMRF beam connection

Oscar,

We used to do this when I was designing a lot of SMFs, but only as an extension on a multi-bay line of frames—never as a one-sided half bay frame. I’ve analyzed a lot of those multi-bay with a half-bay on the end, and I can tell you you get very little (if any) capacity out of such a frame. The only reason I would ever leave them in a design is if I had a cantilever where I was using a full bay as the backspan or if I needed a little nudge to make redundancy work under CBC.

Shaun Dustin, MS, PE

Doctoral Candidate

USTAR Biofuels Initiative

Utah State University
4130 Old Main Hill
Logan, UT 84322

sdustin@cc.usu.edu

435-770-7816

From: OSCAR HENRIQUEZ [mailto:OHENRIQUEZ@ms-ae.com]
Sent: Wednesday, November 21, 2007 5:46 PM
To: seaint@seaint.org
Subject: Steel SMRF beam connection

Can someone tell me if it is allowed, as part of a steel Special Moment Resisting Frame (SMRF) system, to have a beam with a pre-qualified RBS moment connection at one end of the beam and a simple shear connection at the other end of the beam? Without getting into details of why we are doing this, I would like to know if having such connections will disqualify the frame from being a SMRF. If this is not allowed, where is this stated in the CBC or Specifications?

Happy Thanksgiving everyone!

Oscar Henriquez, P.E.

McLean & Schultz

Brea, CA 92801

RE: MODELING: Accounting for a 'Black Box' Supported Structure

I’ve worked on a couple of blast designs but it’s been a year and a half since the last one and I’m no longer current. Contact Jared Adams at SidePlate Systems (jadams@sideplate.com). Jesse Karns at MHP (jkarns@mhpse.com) is very good; he does a lot of nonlinear dynamic analysis for blast and understands the issues better than anyone else I know. Either can point you in the right direction if they have time, but I suspect that the answer you will get will be along the lines of mfg building + blast = bad idea. I suppose it depends on the criteria you have for what “blast resistant” means.

Shaun

Shaun Dustin, MS, PE

Doctoral Candidate

USTAR Biofuels Initiative

Utah State University
4130 Old Main Hill
Logan, UT 84322

sdustin@cc.usu.edu

435-770-7816

From: Bill Polhemus [mailto:bill@polhemus.cc]
Sent: Friday, November 23, 2007 12:39 PM
To: seaint@seaint.org
Subject: MODELING: Accounting for a 'Black Box' Supported Structure

I'm working on a blast-resistant design for a manufactured building that will itself be designed as blast-resistant. However, it will be some weeks before the building's design drawings will be available from the vendor, but the foundation's got to go out now.

The foundation will consist of six or eight drilled shafts that will project eight feet above grade, give or take. I am thinking to have precast prestressed beams in the long direction and precast prestressed hollow-core slabs spanning between them. The model I've constructed uses "beam-column" elements with beam elements spanning as the prestressed beams, and four-node plate elements indicated for each of the hollow core panels. The real purpose for the model actually is to obtain a reasonable value for the natural frequency of the system. I'll confirm the adequacy of the design assuming SDOF and using the SBEDS spreadsheet furnished by the USACE.

All well and good, but I'm wondering what's the best way to account for the presence of the manufactured building. I am using Visual Analysis for this task, which allows the introduction of "lumped masses" at a node - a very convenient feature, much easier to conceptualize than the indirect conversion of weights or loads used by most other programs. But I'm not sure how to account for the dynamic properties of the manufactured building, which I don't really know but can at least approximate for the initial design, then check once we have the numbers from the vendor.

Any comments or suggestions?

RE: CA & WA SE reciprocity

My understanding is that you just need to have 3 years of experience while
being in responsible charge after getting your PE license...anywhere. So,
the clock started "ticking" when I got my PE license in Michigan back in 97
or so. Thus, in theory, I have my 3 years of experience. In otherwords, I
don't believe it needs to be experience after getting your CA PE
license...but after you get a PE license period...but you MUST have your
California PE license in order to get your CA SE license (technically the SE
license is NOT a practice license...thus you need the PE license to practice
and technically, the SE license just gets you the right to call yourself a
structural engineer in California...it is the DSA/other laws that require
schools & hospitals to be designed by SEs...not the licensing board/laws).
Now, I have not been through the process, so I can say that I KNOW this to
be true. But, in theory, I am supposedly at the point where I just need to
fill out the paperwork and get the three references (as I have WAY more than
3 years of experience beyond my first PE license).

And unless they changed it at some point, I believe the special seismic exam
is 2.5 hours long, not 4 hours. At least that was how long it was when I
took it about a 1 1/2 ago. And I would say that the NCEES Struct II exam
was a "real" exam. The NCEES PE and Struct I exams are pathetic and a joke.
And the Struct III in Washington was by far the toughest I took.

Regards,

Scott
Adrian, MI

-----Original Message-----
From: Jake Watson [mailto:jake.watson1@gmail.com]
Sent: Saturday, November 24, 2007 4:18 PM
To: seaint@seaint.org
Subject: Re: CA & WA SE reciprocity

I was told I need 3 years after my CA PE to get a CA SE. This is why they
don't seem to care about the application schedule. You can't possible get
three years of experience between April and October in the same year, right?
After all, engineering does not exist outside CA. By the time the CA folks
told me this, all my patience was gone. I have not verified the actual rules
to determine if this is correct. I did learn that you should personally
verify every statement by reading the rules. And yes, I am a little bitter.

By the way, I also recently heard that CA is no longer accepting ABET
accreditation for colleges. What will happen when people with non CA
degrees start applying for a license in CA?

Now that I have ranted for two days against CA, let me say something
positive. The 4 hour CA special seismic exam (for PE's) was a better
measure of my engineering abilities than the 24 hours of NCEES exams I have
under my belt. I don't know why NCEES can't take a few more cues from CA in
their exams.

Jake Watson, SE
Salt Lake City, UT

On Nov 24, 2007 11:35 AM, Scott Maxwell <smaxwell@umich.edu> wrote:
> I am pretty sure that Jake is correct...even for comity/reciprocity
> from a WA SE to the CA SE, you still need the three years of
> experience AFTER your PE license (I am not sure it has to be in the
> state where you got you first PE...I believe it is just three years of
> experience where YOU are in responsible charge...i.e. sealing
> drawings...in a state where you are
> licensed) and you must have the three SE references. The
comity/reciprosity
> just gets you out of having to take the structural exams in CA. I have my
> SE in WA and supposedly can use it to get my SE in CA. I just need to
fill
> out the paperwork and get three CA SE who will act as references (which I
am
> pretty sure that three people I "know" on this list are willing to do
> that...I have at least one firm offer, but believe two others said they
> would...if I ever get around to filling out the paperwork). Supposedly,
> SEAOC has a "program" that can match you up with CA SEs who would be
willing
> to act as references after reviewing some of your work...if not, then
there
> are folks on this list who might be willing to do it.
>
> Regards,
>
> Scott
> Adrian, MI
>
>
> -----Original Message-----
> From: Jake Watson [mailto:jake.watson1@gmail.com]
> Sent: Friday, November 23, 2007 1:39 PM
> To: seaint@seaint.org
> Subject: Re: CA & WA SE reciprocity
>
>
> CA is extremely difficult to deal with. I am in roughly the same boat
> as you. I got my Utah PE in 2002, CA PE this year (April exam) and
> tried to sit for the October 07 CA SE exam. Didn't happen. CA has
> set the schedule to prohibit someone from coming in and getting a PE
> and SE within the same year, even if they have 30 years out-of-state
> experience. The PE results are issued one week AFTER the registration
> deadline for the fall SE. Not only that, I called CA between when I
> took the exam and when results were issued to check up on my
> application. I was told everything was in order, all I need are the
> results to get my license. Naturally I got a letter a month after I
> was supposed to receive results which told me I as missing the laws
> and rules exam. I had submitted the exam with my application. But
> now I had to wait another month for the board to sit and approve my
> exam. All told, it took me 10 months worth of hassle to get my CA PE.
>
> Did you know that out-of-state CA applications must be post-marked 6
> months before in state applications? Found that out as well when
> trying to apply for the SE. The CA staff is beyond unhelpful in these
> matters. Often giving incorrect advise.
>
> Because of all this hassle, I have reached the same conclusion as you.
> I will attempt the WA SE next fall and then use comity to get a CA SE.
> One other note, the CA SE exam is based on the 97 UBC while the WA SE
> exam is currently based on the 03 IBC. If you have been practicing
> anywhere outside CA, it should be much easier to prepare for the WA
> exam.
>
> I would like to make a couple of notes for you: you will still need
> the CA references once you apply for comity. Read the rules, I
> believe there is a way to get the references even if you don't know
> anyone. A CA SE can review your work or something. I don't remember
> the exact provisions, so look into it. Lastly, it is my experience
> that CA will not budge on the experience issue. Spend your time
> getting the WA SE, by then you will be much closer to your experience
> requirements.
>
> Best of luck, you will need it to deal with CA.
> Jake Watson, SE
> Salt Lake City, UT
>
> On Nov 23, 2007 7:50 AM, Sushil Chauhan <sxchauhan@gmail.com> wrote:
> > Dear All,
> >
> > I am a registered PE (Civil) in California since mid 2005. I had 4
> > years of work-experience before I obtained my CA PE license. I have
> > worked out of California, and on International projects ever since I
> > got my CA PE. Currently I am based in TX.
> >
> > Now I intend to go for CA SE licensing. There are two issues
> > however:
> >
> > 1) Its difficult to get SE references as I never had an opportunity
> > to work with one so far.
> >
> > 2) California board has the requirement that the 3 years of
> > experience after obtaining CA PE license will be counted only if the
> > person was registered PE in the state where he worked. My work
> > history AFTER obtaining CA PE goes like this - (a) 1 year in MD -
> > Had my PE from MD by reciprocity. So I should get 1 year credit from
> > here for sure.
> > (b) Then I moved to Texas and worked on site assignments. By now I
> > have accured over 1 year of experience in TX but I am yet to get TX PE
> > license. I did apply late but its been months since I heard from TX
> > Board people. Apparently this year they had a big backlog. I should be
> > recieving it anytime now.
> >
> > I really want to appear for SE exam in 2008 Fall. Had I worked in CA
> > and under SE's after getting my PE from CA, I would have been
> > eligible for 2008 SE exam.
> >
> > I am thinking of taking following route:
> >
> > 1) Get PE from WA by reciprocity as I already have CA PE
> > 2) Get SE from WA ( I have required experience; my work-experience
> > has been in structural field mostly)
> > 3) Get SE from CA by reciprocity
> >
> > I feel that above route helps me address both of my concerns. WA SE
> > application clearly says that the references could be got from a
> > licensed engineer with significant structural experience and not
> > necessarily SE.
> >
> > Am I thinking straight?
> >
> > Thanks & Regards,
> > SK
>
> ******* ****** ******* ******** ******* ******* ******* ***
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*
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RE: BLACK BOX SUPPORTED STRUCTURE

Over 40 years ago, I attended a seminar at which one of my Structural Engineering heroes, John Minasian, spoke. He had designed the structure for the 605-ft tall Space Needle for the 1962 Seattle World’s Fair. It was designed to resist 200 mph wind and M9.5 earthquake.

I remember John saying that the combined center of gravity of the Tower and its foundation is below grade. The Wikipedia article says that the tower and the foundation each weigh the same and the center of gravity is 5-ft above grade.

John died last month at age 94; an obituary appeared in the December 2007 issue of the SEAOSC News.

Nels Roselund, SE
South San Gabriel, CA

From: ASC [mailto:ggg@bigpond.net.au]
Sent: Saturday, November 24, 2007 2:35 PM
To: Struct EngAssoc
Subject: BLACK BOX SUPPORTED STRUCTURE

From: Bill Polhemus <bill@polhemus.cc>
To: seaint@seaint.org
Subject: MODELING: Accounting for a 'Black Box' Supported Structure

REPLY:

It is so nice about those weekend issues that so few people write

and that you can get some readable stuff then.

I read Bill's monologue with a puzzlement.

Not being a real building engineer, I imagine every building being an order of

magnitude heavier than its footing and peers.

If I am right, then you "account" for footings as an addition to a building, not the other way around.

Or is it a partially underground structure?

Sincerely, Gregory from Oz

Re: Wind tower design

CFD has been around since at least the mid 70's.

My first exposure to is was during a tour (Spring '75) of NASA Ames
Research Center at Moffett Field, CA

They were (at the time) doing some pretty advanced stuff, flow over
the space shuttle during re-entry.
At the time the computational demands were at the very limits of
super-computing capability (think Cray).

http://www.nasa.gov/centers/ames/home/index.html

http://search.nasa.gov/search/search?q=cfd&output=xml_no_dtd&sort=dateADALAd1&site=nasa_collection&ie=UTF-8&client=nasa_production&oe=UTF-8&proxystylesheet=nasa_production

cfd has come a long way in the last 30 years, don't need super
computers to do the more "mainstream" stuff.

but like with any sophisticated analytical tool (like FEM), in the
hands of the inexperienced, the results could be questionable.

I would depend on a wind tunnel modeling expert and someone with
expensive cfd experience and aerodynamic flutter experience.

cheers
Bob

On Nov 24, 2007 11:51 AM, Harold Sprague <spraguehope@hotmail.com> wrote:
>
> Computational Fluid Dynamics. There are several programs that can do this
> kind of work.
>
> Regards,
> Harold Sprague
>
>
> ________________________________
> Date: Wed, 21 Nov 2007 23:03:07 -0500
>
>
> From: kbofoz@gmail.com
> To: seaint@seaint.org
> Subject: Re: Wind tower design
>
> Harold, what is CFD ?
>
>
> On Nov 21, 2007 12:01 PM, Harold Sprague <spraguehope@hotmail.com> wrote:
>
>
> Don't write off circular shapes. The circular shape may be the most
> structurally efficient and most effective for construction. It generally is
> when it comes to stacks in spite of the vortex shedding problem.
>
> Stacks have the same tendency of vortex shedding. It is mitigated by
> strakes or active damping. The blades themselves of a wind power generator
> may mitigate the forming of the vortices.
>
> Regardless, my limited experience with high end computer modeling is that a
> lot of the CFD codes will give you any answer you want. What you need are
> data points that verify the CFD model. I would suggest you speak with Jon
> Peterka at CPP in Ft. Collins. He knows modeling and he knows the
> limitations of CFD modeling. He may have already modeled this.
>
> Regards,
> Harold Sprague
>
>
>
> ________________________________
> Date: Mon, 19 Nov 2007 12:53:55 -0500
>
> From: kbofoz@gmail.com
> To: seaint@seaint.org
>
> Subject: Re: Wind tower design
>
> Thanks for the feedback Harold,
> I am looking at the probability of wind tunnel testing, as well as
> theoretical studies to determine the dynamic properties.
> I will be asking the wind experts about vortex shedding. I will probably be
> using a non-circular cross-section to reduce the vortex shedding, but I
> don't yet know if a hexagonal or pentagonal shape is better than circular.
> I believe the best would be pentagonal, but that will be a discussion with
> the wind tunnel people.
>
> Kevin
>
>
>
> On Nov 19, 2007 12:17 PM, Harold Sprague <spraguehope@hotmail.com> wrote:
>
>
>
> I doubt that you will find any sort of code or design guide on this topic.
> I would suggest that a wind tunnel study be conducted especially if this is
> for operational wind load characteristics. If this is for extreme wind
> effects, I would think that the dominate issue will be the vortex shedding
> on the mast.
>
> Regards,
> Harold Sprague
>
>
> ________________________________
> Date: Fri, 16 Nov 2007 22:02:19 -0500
> From: kbofoz@gmail.com
> To: seaint@seaint.org
> Subject: Wind tower design
>
>
> Has anybody done any wind tower design work ? I am doing some preliminary
> work on a concrete tower design, and I am thinking about the dynamic
> behaviour
> and the effect of the passage of the blade when it passes in front of the
> tower. Does anyone have any information or ideas on this ?
>
> The Germans and the Japanese have actually built some concrete towers
> already. Apparently steel towers are at about their height limit now, and
> the way to greater efficiency and bigger turbines leads to higher towers,
> which will probably be in concrete.
>
>
>
> ________________________________
> Share life as it happens with the new Windows Live. Share now!
>
>
> ________________________________
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BLACK BOX SUPPORTED STRUCTURE

From: Bill Polhemus <bill@polhemus.cc>
To: seaint@seaint.org
Subject: MODELING: Accounting for a 'Black Box' Supported Structure

REPLY:

It is so nice about those weekend issues that so few people write

and that you can get some readable stuff then.

I read Bill's monologue with a puzzlement.

Not being a real building engineer, I imagine every building being an order of

magnitude heavier than its footing and peers.

If I am right, then you "account" for footings as an addition to a building, not the other way around.

Or is it a partially underground structure?

Sincerely, Gregory from Oz

Re: CA & WA SE reciprocity

I was told I need 3 years after my CA PE to get a CA SE. This is why
they don't seem to care about the application schedule. You can't
possible get three years of experience between April and October in
the same year, right? After all, engineering does not exist outside
CA. By the time the CA folks told me this, all my patience was gone.
I have not verified the actual rules to determine if this is correct.
I did learn that you should personally verify every statement by
reading the rules. And yes, I am a little bitter.

By the way, I also recently heard that CA is no longer accepting ABET
accreditation for colleges. What will happen when people with non CA
degrees start applying for a license in CA?

Now that I have ranted for two days against CA, let me say something
positive. The 4 hour CA special seismic exam (for PE's) was a better
measure of my engineering abilities than the 24 hours of NCEES exams I
have under my belt. I don't know why NCEES can't take a few more cues
from CA in their exams.

Jake Watson, SE
Salt Lake City, UT

On Nov 24, 2007 11:35 AM, Scott Maxwell <smaxwell@umich.edu> wrote:
> I am pretty sure that Jake is correct...even for comity/reciprocity from a
> WA SE to the CA SE, you still need the three years of experience AFTER your
> PE license (I am not sure it has to be in the state where you got you first
> PE...I believe it is just three years of experience where YOU are in
> responsible charge...i.e. sealing drawings...in a state where you are
> licensed) and you must have the three SE references. The comity/reciprosity
> just gets you out of having to take the structural exams in CA. I have my
> SE in WA and supposedly can use it to get my SE in CA. I just need to fill
> out the paperwork and get three CA SE who will act as references (which I am
> pretty sure that three people I "know" on this list are willing to do
> that...I have at least one firm offer, but believe two others said they
> would...if I ever get around to filling out the paperwork). Supposedly,
> SEAOC has a "program" that can match you up with CA SEs who would be willing
> to act as references after reviewing some of your work...if not, then there
> are folks on this list who might be willing to do it.
>
> Regards,
>
> Scott
> Adrian, MI
>
>
> -----Original Message-----
> From: Jake Watson [mailto:jake.watson1@gmail.com]
> Sent: Friday, November 23, 2007 1:39 PM
> To: seaint@seaint.org
> Subject: Re: CA & WA SE reciprocity
>
>
> CA is extremely difficult to deal with. I am in roughly the same boat as
> you. I got my Utah PE in 2002, CA PE this year (April exam) and tried to
> sit for the October 07 CA SE exam. Didn't happen. CA has set the schedule
> to prohibit someone from coming in and getting a PE and SE within the same
> year, even if they have 30 years out-of-state experience. The PE results
> are issued one week AFTER the registration deadline for the fall SE. Not
> only that, I called CA between when I took the exam and when results were
> issued to check up on my application. I was told everything was in order,
> all I need are the results to get my license. Naturally I got a letter a
> month after I was supposed to receive results which told me I as missing the
> laws and rules exam. I had submitted the exam with my application. But now
> I had to wait another month for the board to sit and approve my exam. All
> told, it took me 10 months worth of hassle to get my CA PE.
>
> Did you know that out-of-state CA applications must be post-marked 6 months
> before in state applications? Found that out as well when trying to apply
> for the SE. The CA staff is beyond unhelpful in these matters. Often
> giving incorrect advise.
>
> Because of all this hassle, I have reached the same conclusion as you. I
> will attempt the WA SE next fall and then use comity to get a CA SE. One
> other note, the CA SE exam is based on the 97 UBC while the WA SE exam is
> currently based on the 03 IBC. If you have been practicing anywhere outside
> CA, it should be much easier to prepare for the WA exam.
>
> I would like to make a couple of notes for you: you will still need the CA
> references once you apply for comity. Read the rules, I believe there is a
> way to get the references even if you don't know anyone. A CA SE can review
> your work or something. I don't remember the exact provisions, so look into
> it. Lastly, it is my experience that CA will not budge on the experience
> issue. Spend your time getting the WA SE, by then you will be much closer
> to your experience requirements.
>
> Best of luck, you will need it to deal with CA.
> Jake Watson, SE
> Salt Lake City, UT
>
> On Nov 23, 2007 7:50 AM, Sushil Chauhan <sxchauhan@gmail.com> wrote:
> > Dear All,
> >
> > I am a registered PE (Civil) in California since mid 2005. I had 4
> > years of work-experience before I obtained my CA PE license. I have
> > worked out of California, and on International projects ever since I
> > got my CA PE. Currently I am based in TX.
> >
> > Now I intend to go for CA SE licensing. There are two issues however:
> >
> > 1) Its difficult to get SE references as I never had an opportunity to
> > work with one so far.
> >
> > 2) California board has the requirement that the 3 years of experience
> > after obtaining CA PE license will be counted only if the person was
> > registered PE in the state where he worked. My work history AFTER
> > obtaining CA PE goes like this - (a) 1 year in MD - Had my PE from MD
> > by reciprocity. So I should get 1 year credit from here for sure.
> > (b) Then I moved to Texas and worked on site assignments. By now I
> > have accured over 1 year of experience in TX but I am yet to get TX PE
> > license. I did apply late but its been months since I heard from TX
> > Board people. Apparently this year they had a big backlog. I should be
> > recieving it anytime now.
> >
> > I really want to appear for SE exam in 2008 Fall. Had I worked in CA
> > and under SE's after getting my PE from CA, I would have been eligible
> > for 2008 SE exam.
> >
> > I am thinking of taking following route:
> >
> > 1) Get PE from WA by reciprocity as I already have CA PE
> > 2) Get SE from WA ( I have required experience; my work-experience has
> > been in structural field mostly)
> > 3) Get SE from CA by reciprocity
> >
> > I feel that above route helps me address both of my concerns. WA SE
> > application clearly says that the references could be got from a
> > licensed engineer with significant structural experience and not
> > necessarily SE.
> >
> > Am I thinking straight?
> >
> > Thanks & Regards,
> > SK
>
> ******* ****** ******* ******** ******* ******* ******* ***
> * Read list FAQ at: http://www.seaint.org/list_FAQ.asp
> *
> * This email was sent to you via Structural Engineers
> * Association of Southern California (SEAOSC) server. To
> * subscribe (no fee) or UnSubscribe, please go to:
> *
> *

******* ****** ****** ****** ******* ****** ****** ********

RE: Wind tower design

Computational Fluid Dynamics. There are several programs that can do this kind of work.

Regards,
Harold Sprague

Date: Wed, 21 Nov 2007 23:03:07 -0500
From: kbofoz@gmail.com
To: seaint@seaint.org
Subject: Re: Wind tower design

Harold, what is CFD ?

On Nov 21, 2007 12:01 PM, Harold Sprague <spraguehope@hotmail.com> wrote:

Don't write off circular shapes. The circular shape may be the most structurally efficient and most effective for construction. It generally is when it comes to stacks in spite of the vortex shedding problem.

Stacks have the same tendency of vortex shedding. It is mitigated by strakes or active damping. The blades themselves of a wind power generator may mitigate the forming of the vortices.

Regardless, my limited experience with high end computer modeling is that a lot of the CFD codes will give you any answer you want. What you need are data points that verify the CFD model. I would suggest you speak with Jon Peterka at CPP in Ft. Collins. He knows modeling and he knows the limitations of CFD modeling. He may have already modeled this.

Regards,
Harold Sprague

Date: Mon, 19 Nov 2007 12:53:55 -0500

From: kbofoz@gmail.com
To: seaint@seaint.org

Subject: Re: Wind tower design

Thanks for the feedback Harold,
I am looking at the probability of wind tunnel testing, as well as theoretical studies to determine the dynamic properties.
I will be asking the wind experts about vortex shedding. I will probably be using a non-circular cross-section to reduce the vortex shedding, but I don't yet know if a hexagonal or pentagonal shape is better than circular. I believe the best would be pentagonal, but that will be a discussion with the wind tunnel people.

Kevin

On Nov 19, 2007 12:17 PM, Harold Sprague <spraguehope@hotmail.com> wrote:

I doubt that you will find any sort of code or design guide on this topic. I would suggest that a wind tunnel study be conducted especially if this is for operational wind load characteristics. If this is for extreme wind effects, I would think that the dominate issue will be the vortex shedding on the mast.

Regards,
Harold Sprague

Date: Fri, 16 Nov 2007 22:02:19 -0500
From: kbofoz@gmail.com
To: seaint@seaint.org
Subject: Wind tower design

Has anybody done any wind tower design work ? I am doing some preliminary work on a concrete tower design, and I am thinking about the dynamic behaviour
and the effect of the passage of the blade when it passes in front of the tower. Does anyone have any information or ideas on this ?

The Germans and the Japanese have actually built some concrete towers already. Apparently steel towers are at about their height limit now, and the way to greater efficiency and bigger turbines leads to higher towers, which will probably be in concrete.

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RE: CA & WA SE reciprocity

I am pretty sure that Jake is correct...even for comity/reciprocity from a
WA SE to the CA SE, you still need the three years of experience AFTER your
PE license (I am not sure it has to be in the state where you got you first
PE...I believe it is just three years of experience where YOU are in
responsible charge...i.e. sealing drawings...in a state where you are
licensed) and you must have the three SE references. The comity/reciprosity
just gets you out of having to take the structural exams in CA. I have my
SE in WA and supposedly can use it to get my SE in CA. I just need to fill
out the paperwork and get three CA SE who will act as references (which I am
pretty sure that three people I "know" on this list are willing to do
that...I have at least one firm offer, but believe two others said they
would...if I ever get around to filling out the paperwork). Supposedly,
SEAOC has a "program" that can match you up with CA SEs who would be willing
to act as references after reviewing some of your work...if not, then there
are folks on this list who might be willing to do it.

Regards,

Scott
Adrian, MI

-----Original Message-----
From: Jake Watson [mailto:jake.watson1@gmail.com]
Sent: Friday, November 23, 2007 1:39 PM
To: seaint@seaint.org
Subject: Re: CA & WA SE reciprocity

CA is extremely difficult to deal with. I am in roughly the same boat as
you. I got my Utah PE in 2002, CA PE this year (April exam) and tried to
sit for the October 07 CA SE exam. Didn't happen. CA has set the schedule
to prohibit someone from coming in and getting a PE and SE within the same
year, even if they have 30 years out-of-state experience. The PE results
are issued one week AFTER the registration deadline for the fall SE. Not
only that, I called CA between when I took the exam and when results were
issued to check up on my application. I was told everything was in order,
all I need are the results to get my license. Naturally I got a letter a
month after I was supposed to receive results which told me I as missing the
laws and rules exam. I had submitted the exam with my application. But now
I had to wait another month for the board to sit and approve my exam. All
told, it took me 10 months worth of hassle to get my CA PE.

Did you know that out-of-state CA applications must be post-marked 6 months
before in state applications? Found that out as well when trying to apply
for the SE. The CA staff is beyond unhelpful in these matters. Often
giving incorrect advise.

Because of all this hassle, I have reached the same conclusion as you. I
will attempt the WA SE next fall and then use comity to get a CA SE. One
other note, the CA SE exam is based on the 97 UBC while the WA SE exam is
currently based on the 03 IBC. If you have been practicing anywhere outside
CA, it should be much easier to prepare for the WA exam.

I would like to make a couple of notes for you: you will still need the CA
references once you apply for comity. Read the rules, I believe there is a
way to get the references even if you don't know anyone. A CA SE can review
your work or something. I don't remember the exact provisions, so look into
it. Lastly, it is my experience that CA will not budge on the experience
issue. Spend your time getting the WA SE, by then you will be much closer
to your experience requirements.

Best of luck, you will need it to deal with CA.
Jake Watson, SE
Salt Lake City, UT

On Nov 23, 2007 7:50 AM, Sushil Chauhan <sxchauhan@gmail.com> wrote:
> Dear All,
>
> I am a registered PE (Civil) in California since mid 2005. I had 4
> years of work-experience before I obtained my CA PE license. I have
> worked out of California, and on International projects ever since I
> got my CA PE. Currently I am based in TX.
>
> Now I intend to go for CA SE licensing. There are two issues however:
>
> 1) Its difficult to get SE references as I never had an opportunity to
> work with one so far.
>
> 2) California board has the requirement that the 3 years of experience
> after obtaining CA PE license will be counted only if the person was
> registered PE in the state where he worked. My work history AFTER
> obtaining CA PE goes like this - (a) 1 year in MD - Had my PE from MD
> by reciprocity. So I should get 1 year credit from here for sure.
> (b) Then I moved to Texas and worked on site assignments. By now I
> have accured over 1 year of experience in TX but I am yet to get TX PE
> license. I did apply late but its been months since I heard from TX
> Board people. Apparently this year they had a big backlog. I should be
> recieving it anytime now.
>
> I really want to appear for SE exam in 2008 Fall. Had I worked in CA
> and under SE's after getting my PE from CA, I would have been eligible
> for 2008 SE exam.
>
> I am thinking of taking following route:
>
> 1) Get PE from WA by reciprocity as I already have CA PE
> 2) Get SE from WA ( I have required experience; my work-experience has
> been in structural field mostly)
> 3) Get SE from CA by reciprocity
>
> I feel that above route helps me address both of my concerns. WA SE
> application clearly says that the references could be got from a
> licensed engineer with significant structural experience and not
> necessarily SE.
>
> Am I thinking straight?
>
> Thanks & Regards,
> SK

******* ****** ****** ****** ******* ****** ****** ********

Friday, November 23, 2007

MODELING: Accounting for a 'Black Box' Supported Structure

Re: CA & WA SE reciprocity

CA is extremely difficult to deal with. I am in roughly the same boat
as you. I got my Utah PE in 2002, CA PE this year (April exam) and
tried to sit for the October 07 CA SE exam. Didn't happen. CA has
set the schedule to prohibit someone from coming in and getting a PE
and SE within the same year, even if they have 30 years out-of-state
experience. The PE results are issued one week AFTER the registration
deadline for the fall SE. Not only that, I called CA between when I
took the exam and when results were issued to check up on my
application. I was told everything was in order, all I need are the
results to get my license. Naturally I got a letter a month after I
was supposed to receive results which told me I as missing the laws
and rules exam. I had submitted the exam with my application. But
now I had to wait another month for the board to sit and approve my
exam. All told, it took me 10 months worth of hassle to get my CA PE.

Did you know that out-of-state CA applications must be post-marked 6
months before in state applications? Found that out as well when
trying to apply for the SE. The CA staff is beyond unhelpful in these
matters. Often giving incorrect advise.

Because of all this hassle, I have reached the same conclusion as you.
I will attempt the WA SE next fall and then use comity to get a CA
SE. One other note, the CA SE exam is based on the 97 UBC while the
WA SE exam is currently based on the 03 IBC. If you have been
practicing anywhere outside CA, it should be much easier to prepare
for the WA exam.

I would like to make a couple of notes for you: you will still need
the CA references once you apply for comity. Read the rules, I
believe there is a way to get the references even if you don't know
anyone. A CA SE can review your work or something. I don't remember
the exact provisions, so look into it. Lastly, it is my experience
that CA will not budge on the experience issue. Spend your time
getting the WA SE, by then you will be much closer to your experience
requirements.

Best of luck, you will need it to deal with CA.
Jake Watson, SE
Salt Lake City, UT

On Nov 23, 2007 7:50 AM, Sushil Chauhan <sxchauhan@gmail.com> wrote:
> Dear All,
>
> I am a registered PE (Civil) in California since mid 2005. I had 4 years of
> work-experience before I obtained my CA PE license. I have worked out of
> California, and on International projects ever since I got my CA PE.
> Currently I am based in TX.
>
> Now I intend to go for CA SE licensing. There are two issues however:
>
> 1) Its difficult to get SE references as I never had an opportunity to work
> with one so far.
>
> 2) California board has the requirement that the 3 years of experience after
> obtaining CA PE license will be counted only if the person was registered PE
> in the state where he worked. My work history AFTER obtaining CA PE goes
> like this - (a) 1 year in MD - Had my PE from MD by reciprocity. So I should
> get 1 year credit from here for sure.
> (b) Then I moved to Texas and worked on site assignments. By now I have
> accured over 1 year of experience in TX but I am yet to get TX PE license. I
> did apply late but its been months since I heard from TX Board people.
> Apparently this year they had a big backlog. I should be recieving it
> anytime now.
>
> I really want to appear for SE exam in 2008 Fall. Had I worked in CA and
> under SE's after getting my PE from CA, I would have been eligible for 2008
> SE exam.
>
> I am thinking of taking following route:
>
> 1) Get PE from WA by reciprocity as I already have CA PE
> 2) Get SE from WA ( I have required experience; my work-experience has been
> in structural field mostly)
> 3) Get SE from CA by reciprocity
>
> I feel that above route helps me address both of my concerns. WA SE
> application clearly says that the references could be got from a licensed
> engineer with significant structural experience and not necessarily SE.
>
> Am I thinking straight?
>
> Thanks & Regards,
> SK

******* ****** ****** ****** ******* ****** ****** ********

CA & WA SE reciprocity

Dear All,

I am a registered PE (Civil) in California since mid 2005. I had 4 years of work-experience before I obtained my CA PE license. I have worked out of California, and on International projects ever since I got my CA PE. Currently I am based in TX.

Now I intend to go for CA SE licensing. There are two issues however:

1) Its difficult to get SE references as I never had an opportunity to work with one so far.

2) California board has the requirement that the 3 years of experience after obtaining CA PE license will be counted only if the person was registered PE in the state where he worked. My work history AFTER obtaining CA PE goes like this - (a) 1 year in MD - Had my PE from MD by reciprocity. So I should get 1 year credit from here for sure.

(b) Then I moved to Texas and worked on site assignments. By now I have accured over 1 year of experience in TX but I am yet to get TX PE license. I did apply late but its been months since I heard from TX Board people. Apparently this year they had a big backlog. I should be recieving it anytime now.

I really want to appear for SE exam in 2008 Fall. Had I worked in CA and under SE's after getting my PE from CA, I would have been eligible for 2008 SE exam.

I am thinking of taking following route:

1) Get PE from WA by reciprocity as I already have CA PE

2) Get SE from WA ( I have required experience; my work-experience has been in structural field mostly)

3) Get SE from CA by reciprocity

I feel that above route helps me address both of my concerns. WA SE application clearly says that the references could be got from a licensed engineer with significant structural experience and not necessarily SE.

Am I thinking straight?

Thanks & Regards,

Thursday, November 22, 2007

RE: Strap and Tie-Down Systems Part 2 by Alfred Commins

That would be the hand drill with the 1" bit for the 7/8" bolt (snugly fit,
of course) but the center of the drill chuck rotates in a clockwise motion
following an orbit of about 12" diameter about the center of the hole.

Ah, yes....I know it well...

>
> ------------------------------------------------------------------------
What he said.
Chuck Utzman, PE
I saw too many installations where the drilled holes didn't align & were
finished off with what we call a "Mexican milling machine"

******* ****** ****** ****** ******* ****** ****** ********

Re: Strap and Tie-Down Systems Part 2 by Alfred Commins

Donald Bruckman wrote:
>
> I haven't used those HPAHD (used to be just PA) straps since the 80s
> and I believe they were outlawed in the City of Los Angeles in about
> 1992. I can't believe Simpson even produces them anymore.
>
> As for the old bolted holddowns, (HD series), I don't think anyone
> that has ever installed a PHD series holddown and their brethren would
> say that the bolted versions were superior, at least anecdotally. I
> guess we'll all find out if we're idiots or not when the next big
> shaker arrives since I don't believe they existed prior to '94 and
> thus haven't been put thru Mother Nature's testing program, but so
> far, I'm a big fan of the SDS screw both for hold-downs and also sill
> transfer because I"ve never been too comfortable with that "re-tighten
> the bolt just before covering" thang….
>
> ------------------------------------------------------------------------
What he said.
Chuck Utzman, PE
I saw too many installations where the drilled holes didn't align & were
finished off with what we call a "Mexican milling machine"

******* ****** ****** ****** ******* ****** ****** ********

RE: Strap and Tie-Down Systems Part 2 by Alfred Commins

I haven’t used those HPAHD (used to be just PA) straps since the 80s and I believe they were outlawed in the City of Los Angeles in about 1992. I can’t believe Simpson even produces them anymore.

As for the old bolted holddowns, (HD series), I don’t think anyone that has ever installed a PHD series holddown and their brethren would say that the bolted versions were superior, at least anecdotally. I guess we’ll all find out if we’re idiots or not when the next big shaker arrives since I don’t believe they existed prior to ’94 and thus haven’t been put thru Mother Nature’s testing program, but so far, I’m a big fan of the SDS screw both for hold-downs and also sill transfer because I”ve never been too comfortable with that “re-tighten the bolt just before covering” thang….

From: WISH DENNIS [mailto:dennis.wish@verizon.net]
Sent: Tuesday, November 20, 2007 2:55 PM
To: SEAINT Listservice
Subject: Strap and Tie-Down Systems Part 2 by Alfred Commins

In the November issue of Structure Magazine, I read Alfred Commins article on strap-tie down's commonly used for tracts and lower income residential almost esclusively in my area of California. With a few exceptions, I think Commin's is right on the mark with his comments and recommendations to retire strap systems such as HPAHD produced by Simpson and others (I think this is the right number although I do not specify these types of holddowns for the same reason's Commins points to). I live in an area of highly mineralized soils and with builders to cut corners by eliminating templates when embedding strap-ties for hold down systems. In addition to the spalling of the concrete, a majority of these straps are left exposed sufficiently to become wet through irregation systems as simple as lawn sprinklers. I once discussed with the Simpson's R&D who estimated the life span of a strap-tie at less than 5 years in a highly mineralized region.

It appears to me that Commins comments are on the mark and possibly many of have known this for many years. What strikes me is that developers of high-end homes have still used these ties in $1M plus homes and their comments have all been the same; The code allows it and they have the right to use it under a free enterprise system. However, if they retire these straps, the damage done will likely become the damage to be done and what will we do before the costly effects of deterioration and rust take its toll in a high seismic region.

I am not sure that the concentric holddown connector that Commins recommends is the answer because of cost and installation, however, Northridge and Loma Prieta seemed to draw early conclusions as to eccentric holddown placement. My position on this was always to recommend a Hold down system that was screwed rather than bolted since it seemed to provide easiest solution at the best price when looking at the Simpson Catalog (which I assume is comparable to USP and/or Silver (if they are still around)). Bolted problems with the eccentric HD's have proven to be somewhat of a problem, but I am not sure that I would recommend reduction in capacity where screwed connections such as the SDS1/4 are used. The deflection of the bolted holddown might also have an alternative solution if one can be presented such as the use of tandem bolts and screwed connections or possible a bent press-pin in the flange of the HD or an epoxy connection between plates (with holes added) that would create greater friction between the bolted HD plate and the surface of the wood.

Has anyone given thought to the thousands of homes that have used straps in high seismic regions and considered the potential ramification for failure of the straps due to enviornment and a necessary retrofit scheme if any part of the strap is visible from outside the concrete?

This sounds like a highly charged subject that I have been aware of for many years and have done everything down to refusing work from developers who are adament about the use of these straps unless the project is borderline Prescriptive (UBC 2320) that does not require hold downs for braced panels.

Dennis

Dennis S. Wish, PE
California Professional Engineer
Structural Engineering Consultant

RE: ASCE 7-05 Wind

Actually, ASCE 7 now also has corner zones for MFWRS. It used to only be for C&C (in older ASCE 7 editions and BOCA codes). This is the one area where I think that the ASCE 7 went overboard. In general, having ONE uniform pressure (or increasing pressure with height on the windward side) makes a lot more sense. The corner zones for MWFRS seems to be an over complication to me. I suppose there might be situations where accounting for the increase in wind pressure at corners might have some effects (i.e. non-symmetrical buildings that are torsion sensative), but by and large, it should have a rather insignificant effect. Like Jordan, I tend to just take the corner pressures (which are the "worst" case) and use it for the whole building (or use something between the main portion pressures and the corner pressures if I don't want to be WAY conservative)...but that can be conservative.

Regards,

Scott

Adrian, MI

-----Original Message-----
From: Neil Moore [mailto:nma@omsoft.com]
Sent: Wednesday, November 21, 2007 6:27 PM
To: seaint@seaint.org; seaint@seaint.org
Subject: Re: ASCE 7-05 Wind

Corner zones is in the UBC Section 1622 when you are designing your walls for out of plane loads and are areas of discontinuities and areas not in areas of discontinuities.

In ASCE 7 they are talking about Components and Cladding or C&C's.   Deflection ratios in the CBC will require anywhere from L/240 for brittle finishes to L/120 for flexible finishes per Table 1604.3.

Actually there is a whole host of wind items that should be considered.   We don't hear much about roof's blowing off, but they do happen. Sometimes you can look at a scalloped stucco wall and wonder if they built it that way!    If you research some of the big wind storms in Northern California, you'll find some Category 2 wind records. I can remember the big wind storm that trashed Sacramento in 1938.   I was about six and my dad was later in the backyard cleaning up the mess.

Sometimes we have little tornadoes like the one that touched down in the Natomas area north of Sacramento a couple of years ago.   Watched the cloud for an hour coming up Highway 5 and the big dark cloud finally let a little funnel snake down. Wife took a picture through the windshield!

Lately I've been using the wind program from MECA.   It's even got a section in there for Kzt.

Neil Moore, SE, SECB

At 01:50 PM 11/21/2007, WISH DENNIS wrote:
Jordan,
Help me to understand "corner zones"? This is what seems to be confusing me. I have not yet paid close enough attention to comparing the zones on the various model analysis I've seen, so please bear with me. Regardless of the shape of the building (with or without reentrant corners and interior shear walls) can the engineer simplify the MWFRS down to a uniform load applied tributary to each diaprhagm and then compared to wind OR is this too conservative?
Maybe if you could just explain briefly what the code is attempting to do different from the UBC conventional methods that those of us only know? For example, simply start with some rhetoric about corner zones and idea behind breaking the building down into zones to start with. This might help some of us who have the codes but do not fully follow the logic.

Dennis S. Wish, PE
California Professional Engineer
Structural Engineering Consultant

----- Original Message ----
From: "Jordan Truesdell, PE" <seaint2@truesdellengineering.com>
To: seaint@seaint.org
Sent: Wednesday, November 21, 2007 9:15:58 AM
Subject: Re: ASCE 7-05 Wind

You are absolutely correct. As a practicing engineer being held to the standards commonly exercised by others who practice in my field, I would request that you continue to ignore that particular section of ASCE-7. If we all ignore it, then we are all acting in a common way.

That said, this is an area where engineering judgment has to control. I would suggest that any building which does not resemble an airfoil is going to be regular, regardless of the definition proposed by the non-practicing professor who decided it would be a good idea to wind-tunnel test every L shaped strip mall. I typically analyze non-rectangular structures by taking corner zones at every corner which could reasonably result in turbulence, and fudge the data for rounded areas. Maybe I'm cavalier because of my aero background, or maybe I'm just naive; if I'm ever confronted, I will happily pass on the building official's requirement that wind tunnel testing be done. I'll either end up with an enormous fee, or the official will be run out of town by builders with pitchforks and torches - I win no matter what.

What you will like in ASCE 7-05 provisions is that they have greatly expanded the types of conditions for which equations and drag factors area available. It will take a little bit to go through, but if you've ever been frustrated by the lack of guidance on odd shaped areas in previous editions, you'll find that many questions are answered in 7-05 (even if there are still many gaps).
Jordan
Doug Mayer wrote:

I am making the transition to the new code (CBC 2007) and being confronted with the ASCE wind provisions. They seem astoundingly complex and I have a couple of questions that desperately need some answers.

First off, what is a “regular-shaped building”? ASCE defines this as “a building or other structure having no unusual geometrical irregularity in spatial form.” To me, this sounds like any non-rectangular structural is irregular. Is this true? This is very important because it leads into the next question of which analysis method to use. Both Method 1 and Method 2 require “the building or other structure…” to be “… a regular-shaped building or structure as defined in Section 6.2.” This would seem to indicate that you have to use Method 3 (wind tunnel testing!) for an non-rectangular building. I can’t believe that is the case, so I think the definition of a regular-shaped building is different than what it seems to be.

Any help would be greatly appreciated. Also, I apologize if I am asking questions that have already been asked.

TIA,

Doug Mayer, SE

Structural Engineer

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Re: Wind tower design

Kevin et al,
I went to a technical seminar a while ago sponsored by the local Niagara
area building officials where RWDI from Guelph made a presentation. It
included a video about simulated wind testing in a water tank with a
fine sand about the consistency of icing sugar. The flow of water
caused the sand to flow and drift and they were able to measure the
results. The tank was relatively small compared to wind tunnel.
Perhaps this is the basis for some of this CFD.
Gary

Kevin Below wrote:
> So CFD is a method which can be used to simulate air flow around
> objects, and come up with wind pressures ? I had never heard of it.
>
>
> On Nov 21, 2007 11:17 PM, Conrad Harrison < sch.tectonic@bigpond.com
> <mailto:sch.tectonic@bigpond.com>> wrote:
>
> Being as I'm here!
>
>
>
> CFD =computational fluid dynamics
>
>
>
> And from recent articles I have read, it is still early days
> regarding wind loading, and can take hours to days for the
> computer to crunch the numbers. It still largely a research tool
> with few practical programs available.
>
>
>
> It is also used for research into fire behaviour.
>
>
>
> Regards
>
> Conrad Harrison
>
> B.Tech (mfg & mech), MIIE, gradTIEAust
>
> mailto:sch.tectonic@bigpond.com
>
> Adelaide
>
> South Australia
>
> ------------------------------------------------------------------------
>
> *From:* Kevin Below [mailto:kbofoz@gmail.com
> <mailto:kbofoz@gmail.com>]
> *Sent:* Thursday, 22 November 2007 14:33
>
> *To:* seaint@seaint.org <mailto:seaint@seaint.org>
> *Subject:* Re: Wind tower design
>
>
>
> Harold, what is CFD ?
>
> On Nov 21, 2007 12:01 PM, Harold Sprague <spraguehope@hotmail.com
> <mailto:spraguehope@hotmail.com>> wrote:
>
> Don't write off circular shapes. The circular shape may be the
> most structurally efficient and most effective for construction.
> It generally is when it comes to stacks in spite of the vortex
> shedding problem.
>
> Stacks have the same tendency of vortex shedding. It is mitigated
> by strakes or active damping. The blades themselves of a wind
> power generator may mitigate the forming of the vortices.
>
> Regardless, my limited experience with high end computer modeling
> is that a lot of the CFD codes will give you any answer you want.
> What you need are data points that verify the CFD model. I would
> suggest you speak with Jon Peterka at CPP in Ft. Collins. He
> knows modeling and he knows the limitations of CFD modeling. He
> may have already modeled this.
>
> Regards,
> Harold Sprague
>
> ------------------------------------------------------------------------
>
> Date: Mon, 19 Nov 2007 12:53:55 -0500
>
>
> From: kbofoz@gmail.com <mailto:kbofoz@gmail.com>
> To: seaint@seaint.org <mailto:seaint@seaint.org>
>
> Subject: Re: Wind tower design
>
> Thanks for the feedback Harold,
> I am looking at the probability of wind tunnel testing, as well as
> theoretical studies to determine the dynamic properties.
> I will be asking the wind experts about vortex shedding. I will
> probably be using a non-circular cross-section to reduce the
> vortex shedding, but I don't yet know if a hexagonal or pentagonal
> shape is better than circular. I believe the best would be
> pentagonal, but that will be a discussion with the wind tunnel
> people.
>
> Kevin
>
> On Nov 19, 2007 12:17 PM, Harold Sprague <spraguehope@hotmail.com
> <mailto:spraguehope@hotmail.com>> wrote:
>
> I doubt that you will find any sort of code or design guide on
> this topic. I would suggest that a wind tunnel study be
> conducted especially if this is for operational wind load
> characteristics. If this is for extreme wind effects, I would
> think that the dominate issue will be the vortex shedding on
> the mast.
>
> Regards,
> Harold Sprague
>
> ------------------------------------------------------------------------
>
> Date: Fri, 16 Nov 2007 22:02:19 -0500
> From: kbofoz@gmail.com <mailto:kbofoz@gmail.com>
> To: seaint@seaint.org <mailto:seaint@seaint.org>
> Subject: Wind tower design
>
>
>
> Has anybody done any wind tower design work ? I am doing some
> preliminary work on a concrete tower design, and I am thinking
> about the dynamic behaviour
> and the effect of the passage of the blade when it passes in
> front of the tower. Does anyone have any information or ideas
> on this ?
>
> The Germans and the Japanese have actually built some concrete
> towers already. Apparently steel towers are at about their
> height limit now, and the way to greater efficiency and bigger
> turbines leads to higher towers, which will probably be in
> concrete.
>
>
>
> ------------------------------------------------------------------------
>
> Share life as it happens with the new Windows Live. Share now!
> <http://www.windowslive.com/share.html?ocid=TXT_TAGLM_Wave2_sharelife_112007>
>
>
>
>
>
> ------------------------------------------------------------------------
>
> Share life as it happens with the new Windows Live. Share now!
> <http://www.windowslive.com/share.html?ocid=TXT_TAGLM_Wave2_sharelife_112007>
>
>
>
>

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Re: PEMB foundation uplift

I don't count on them as you never know when some owner will want to cut
out that tie beam or floor to put in a service trench or a new truck dock.
Gary

Truitt Vance wrote:
>
> Looking for some opinion here:
>
> I am designing the pads under some columns on a steel PEMB for uplift:
>
> Is it common to use the dead weight for a reasonable length of the tie
> beams intersecting the pads under the columns of a PEMB? Is it common
> to use the weight contribution from a reasonable area of the slab?
>
> If yes, how would you justify that with calcs? (ie: "FBD cut at the
> location where you assumed the contribution of dead weight ended and
> design for the self weight?)
>
> Thank you in advance,
>
> Truitt Vance, P.E.
>

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Wednesday, November 21, 2007

Re: Wind Uplift on Footings

Butler has a few copies left and will sell them to their local Butler
Builders for $15 each. Tell the Butler builder to look on the in house web
site and they will find them there. You would have to contact the authors
(Computerized Structural Design, Milwaukee, Wisconsin, Donald R. Buettner,
Ph.d, P.E.; James M. Fisher, Ph.d, P.E.; Charles E. Mansake, M.S., P.E.) to
see if there are any pdf versions available. The book is out of print as
far as I know so what they have is all there is.

Jim Hanah

----- Original Message -----
From: "Drew Morris" <dmorris@bbfm.com>
To: <seaint@seaint.org>
Sent: Wednesday, November 21, 2007 3:49 PM
Subject: Re: Wind Uplift on Footings

> Harold Sprague wrote:
>>
>> The book "Foundation Design and Construction Manual" by Butler and CSD
>> "recommends" a SF of 1.5.
> Does anyone know whether this book is available. I can't find it on the
> Butler site and I had read that it is out of print. Does anyone have a
> PDF of this?
>
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