Structural Engineering: 2008-02-24

Saturday, March 1, 2008

Re: Concrete exposed to seawater

You can also go to cement.org, and the standard specs for DOT's for CA, FL, OR or WA which I believe are available online....also make sure you use a well graded aggregate mix as you want as much of an even distribution of cement paste that you can achieve, without a lot of cracking.....

----- Original Message -----
From: William.Sherman@CH2M.com
To: seaint@seaint.org
Subject: Concrete exposed to seawater
Date: Fri, 29 Feb 2008 16:17:06 -0700

Do any ACI codes or standards specifically address concrete cover requirements for concrete:

a. Directly exposed to seawater.

b. Exposed to salt laden air (coastal structures not in direct contact with seawater).

I am aware of some discussion in some ACI guides and commentaries and some requirements in European standards, but I am looking for "mandatory language" documents in the U.S.

Bill

William Sherman - CH2M HILL / Denver

Principal Structural Technologist

Structural Global Technology Leader - Water Business Group

william.sherman@ch2m.com

720.286.2792

Bart Needham, SE Principal, nbse associates, inc. civil & structural engineers Office 206-780-6822 Office 805-452-8152 Fax    206-780-6683 Fax    208-693-3667 Mobile 206-300-2346  Office locations: 629 State Street #230 Santa Barbara, CA  93101  205 Fairview Lane Suite 100 Paso Robles, CA  93446  365 Ericksen Ave. NE Suite 328 Bainbridge Island, WA  98110  Mail and Deliveries: 321 High School Rd. NE Suite D-3 PMB 216 Bainbridge Island, WA  98110

Re: Sign Structures

How did you know I was winging when I designed the sign?
Gary

Neil Moore wrote:
> Who gets hurt if the sign decides to be a wild wing?
>
> Neil Moore, SE, SECB
>
>
>
> At 09:15 AM 2/29/2008, you wrote:
>> A "dynamic" analysis for a billboard.... Tomfoolery at its highest...
>>
>> On Fri, Feb 29, 2008 at 5:00 AM, Gary L. Hodgson and Assoc.
>> <ghodgson@bellnet.ca <mailto:ghodgson@bellnet.ca>> wrote:
>>
>> Thanks, Harold
>> I will be doing that. There is no guidance in our codes on signs or
>> other non-building structures. Your codes go further than ours,
>> as ours
>> are only written in regard to buildings. If I want to design a crane
>> runway, storage bin, or sign _for seismic loads_, I have to refer to
>> American publications. The problem is that our codes don't use
>> the same
>> terms or geographical data.
>> In going up against this municipality, I have to be on firm footing,
>> because my customer has a history of bad relations with them--he
>> has won
>> two law suits against the city and their three page letter (of
>> structural questions only) came two days after the latest
>> judgement was
>> published in the newspaper. This city has the first or second
>> highest
>> average income in Canada and they don't like billboard signs, even if
>> though there a lot of them existing in the city. One of the
>> questions
>> was "did I do a dynamic analysis of the structure" (for a 20'x10'
>> sign
>> with a top at 25' above grade).
>> Gary
>> How many cases of beer do I owe you now?
>>
>> Harold Sprague wrote:
>> > Gary,
>> > The projected area in the plane of the sign is relatively small.
>> > Seismic may govern. You could categorize signs as nonbuilding
>> > structures. The loading is a function of the force resisting
>> system
>> > which establishes the response coefficient and the mass.
>> >
>> > Regards,
>> > Harold Sprague
>> >
>> > > Date: Thu, 28 Feb 2008 17:04:42 -0500
>> > > From: ghodgson@bellnet.ca <mailto:ghodgson@bellnet.ca>
>> > > To: seaint@seaint.org <mailto:seaint@seaint.org>
>> > > Subject: Sign Structures
>> > >
>> > > List,
>> > > I design sign structures for 2 clients-these are all
>> free-standing
>> > signs
>> > > on one or two posts. In our area, generally wind governs. A
>> > > municipality has questioned whether I designed a particular
>> sign for
>> > > seismic loading. Nothing in our codes addresses the issue of
>> signs
>> > > subject to seismic loading unless they are part of a
>> building, in which
>> > > case they are considered a fixture just like a mechanical
>> piece of
>> > > equipment. Our codes only require that signs over a certain
>> height or
>> > > area have to be designed by a professional engineer. So, I
>> guess my
>> > > question is what seismic loading do you design signs for?
>> Thanks in
>> > > advance.
>> > > Gary
>> >
>> >
>> ------------------------------------------------------------------------
>> > Need to know the score, the latest news, or you need your
>> Hotmail®-get
>> > your "fix". Check it out. <
>>

http://www.msnmobilefix.com/Default.aspx>
>>
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Friday, February 29, 2008

Re: Concrete exposed to seawater

I recommend using twice normal cover. A pier in South Laguna had to be torn down only 20 years after it was built due to corrosion of rebars. Also use high cement content, such as 7 sack/cu. yd. min.
Also use epoxy coated rebar. I have had a lot of experience with the Santa Monica Pier.

Stan Scholl, P.E.
Laguna Beach, CA
_____________________________________________________________
Click for free info on business schools, $150K/ year potential.
http://thirdpartyoffers.juno.com/TGL2111/fc/Ioyw6iieXEFZFgGv2TD8felzgZGu193OqkeJVxqRTp2HsrmVq7EfgX/

Re: Concrete exposed to seawater

I remember doing some research for something similar, and I found an USACE or NAVFAC doc that mentioned something like 4" clear cover for piers. Check the UFC (Unified Facilities Criteria). http://www.wbdg.org/ccb/browse_cat.php?o=29&c=4
HTH

On Fri, Feb 29, 2008 at 3:17 PM, <William.Sherman@ch2m.com> wrote:

Do any ACI codes or standards specifically address concrete cover requirements for concrete:

a. Directly exposed to seawater.

b. Exposed to salt laden air (coastal structures not in direct contact with seawater).

I am aware of some discussion in some ACI guides and commentaries and some requirements in European standards, but I am looking for "mandatory language" documents in the U.S.

Bill

William Sherman - CH2M HILL / Denver

Principal Structural Technologist

Structural Global Technology Leader - Water Business Group

william.sherman@ch2m.com

720.286.2792

--
David Topete, SE

Concrete exposed to seawater

Do any ACI codes or standards specifically address concrete cover requirements for concrete:

a. Directly exposed to seawater.

b. Exposed to salt laden air (coastal structures not in direct contact with seawater).

I am aware of some discussion in some ACI guides and commentaries and some requirements in European standards, but I am looking for "mandatory language" documents in the U.S.

Bill

William Sherman - CH2M HILL / Denver

Principal Structural Technologist

Structural Global Technology Leader - Water Business Group

william.sherman@ch2m.com

720.286.2792

Re: Sign Structures

No problem with that. On a 25' tall billboard, I believe a dynamic analysis is a wee bit excessive...

On Fri, Feb 29, 2008 at 2:51 PM, Harold Sprague <spraguehope@hotmail.com> wrote:

The sign in question does not warrent a dynamic analysis, but there are signs along the strip in Las Vegas that sometimes are evaluated in wind tunnels with modifications at the base to determine a dynamic response.

The Hilton sign in Las Vegas is 279' tall with a terrible plan and elevation aspect ratio. The sign it replaced blew down in a wind storm.

Regards,
Harold Sprague

Date: Fri, 29 Feb 2008 09:15:41 -0800
From: d.topete73@gmail.com
To: seaint@seaint.org
Subject: Re: Sign Structures

A "dynamic" analysis for a billboard.... Tomfoolery at its highest...

On Fri, Feb 29, 2008 at 5:00 AM, Gary L. Hodgson and Assoc. <ghodgson@bellnet.ca> wrote:

Thanks, Harold
I will be doing that. There is no guidance in our codes on signs or
other non-building structures. Your codes go further than ours, as ours
are only written in regard to buildings. If I want to design a crane
runway, storage bin, or sign _for seismic loads_, I have to refer to
American publications. The problem is that our codes don't use the same
terms or geographical data.
In going up against this municipality, I have to be on firm footing,
because my customer has a history of bad relations with them--he has won
two law suits against the city and their three page letter (of
structural questions only) came two days after the latest judgement was
published in the newspaper. This city has the first or second highest
average income in Canada and they don't like billboard signs, even if
though there a lot of them existing in the city. One of the questions
was "did I do a dynamic analysis of the structure" (for a 20'x10' sign
with a top at 25' above grade).
Gary
How many cases of beer do I owe you now?

Harold Sprague wrote:
> Gary,
> The projected area in the plane of the sign is relatively small.
> Seismic may govern. You could categorize signs as nonbuilding
> structures. The loading is a function of the force resisting system
> which establishes the response coefficient and the mass.
>
> Regards,
> Harold Sprague
>
> > Date: Thu, 28 Feb 2008 17:04:42 -0500
> > From: ghodgson@bellnet.ca
> > To: seaint@seaint.org
> > Subject: Sign Structures
> >
> > List,
> > I design sign structures for 2 clients-these are all free-standing
> signs
> > on one or two posts. In our area, generally wind governs. A
> > municipality has questioned whether I designed a particular sign for
> > seismic loading. Nothing in our codes addresses the issue of signs
> > subject to seismic loading unless they are part of a building, in which
> > case they are considered a fixture just like a mechanical piece of
> > equipment. Our codes only require that signs over a certain height or
> > area have to be designed by a professional engineer. So, I guess my
> > question is what seismic loading do you design signs for? Thanks in
> > advance.
> > Gary
>

Helping your favorite cause is as easy as instant messaging. You IM, we give. Learn more.

--
David Topete, SE

RE: Sign Structures

The sign in question does not warrent a dynamic analysis, but there are signs along the strip in Las Vegas that sometimes are evaluated in wind tunnels with modifications at the base to determine a dynamic response.

The Hilton sign in Las Vegas is 279' tall with a terrible plan and elevation aspect ratio. The sign it replaced blew down in a wind storm.

Regards,
Harold Sprague

Date: Fri, 29 Feb 2008 09:15:41 -0800
From: d.topete73@gmail.com
To: seaint@seaint.org
Subject: Re: Sign Structures

A "dynamic" analysis for a billboard.... Tomfoolery at its highest...

On Fri, Feb 29, 2008 at 5:00 AM, Gary L. Hodgson and Assoc. <ghodgson@bellnet.ca> wrote:

Thanks, Harold
I will be doing that. There is no guidance in our codes on signs or
other non-building structures. Your codes go further than ours, as ours
are only written in regard to buildings. If I want to design a crane
runway, storage bin, or sign _for seismic loads_, I have to refer to
American publications. The problem is that our codes don't use the same
terms or geographical data.
In going up against this municipality, I have to be on firm footing,
because my customer has a history of bad relations with them--he has won
two law suits against the city and their three page letter (of
structural questions only) came two days after the latest judgement was
published in the newspaper. This city has the first or second highest
average income in Canada and they don't like billboard signs, even if
though there a lot of them existing in the city. One of the questions
was "did I do a dynamic analysis of the structure" (for a 20'x10' sign
with a top at 25' above grade).
Gary
How many cases of beer do I owe you now?

Harold Sprague wrote:
> Gary,
> The projected area in the plane of the sign is relatively small.
> Seismic may govern. You could categorize signs as nonbuilding
> structures. The loading is a function of the force resisting system
> which establishes the response coefficient and the mass.
>
> Regards,
> Harold Sprague
>
> > Date: Thu, 28 Feb 2008 17:04:42 -0500
> > From: ghodgson@bellnet.ca
> > To: seaint@seaint.org
> > Subject: Sign Structures
> >
> > List,
> > I design sign structures for 2 clients-these are all free-standing
> signs
> > on one or two posts. In our area, generally wind governs. A
> > municipality has questioned whether I designed a particular sign for
> > seismic loading. Nothing in our codes addresses the issue of signs
> > subject to seismic loading unless they are part of a building, in which
> > case they are considered a fixture just like a mechanical piece of
> > equipment. Our codes only require that signs over a certain height or
> > area have to be designed by a professional engineer. So, I guess my
> > question is what seismic loading do you design signs for? Thanks in
> > advance.
> > Gary
>

Helping your favorite cause is as easy as instant messaging. You IM, we give. Learn more.

RE: AISC eLearning

There's voluntary stuff, like my mentoring the student. It will cost
you in time but not in cash. You can get creative all you want (like my
carbon fiber race car parts), but you will have to present it to the
State Board for their approval, kind of like applying for a grant.
For my race car parts, I'm testing flat carbon fiber panels that are
secondary supports for a chassis stiffener in bending. My theory is
that it can be subject to sudden overloads similar to seismic overloads.
I've had to instrument this thing to document the loading conditions so
I can attempt to relate them to a seismic type load. Frankly, I'm
having difficulty here. But it's points in the PDH box. (And, no, I'm
not winning any races but it spooks the competition to see a mysterious
fiber carbon element with all the gages and wires on it.)

Bob

-----Original Message-----
From: t.w.allen@cox.net [mailto:t.w.allen@cox.net]
Sent: Friday, February 29, 2008 2:05 PM
To: seaint@seaint.org
Subject: RE: AISC eLearning

I don't know about the rest, but the SEAOC activities I go to which
provide PDHs are not free.

T. William (Bill) Allen, S.E. (CA#2607)
Allen Designs
Consulting Structural Engineers
San Juan Capistrano, CA

---- "Garner wrote:
> Active involvement in Structural Engineers Association activities

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

RE: AISC eLearning

I don't know about the rest, but the SEAOC activities I go to which provide PDHs are not free.

T. William (Bill) Allen, S.E. (CA#2607)
Allen Designs
Consulting Structural Engineers
San Juan Capistrano, CA

---- "Garner wrote:
> Active involvement in Structural Engineers Association activities

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

Safety factors for attaching screws to OSB

I have it in my mind that the recommended safety factor for screws in
withdrawal from OSB is a minimum of 4. Does anyone know what APA
publication lists this? I have been searching the publications that I
have and cannot find it. I have a call into APA.

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

RE: AISC eLearning

Active involvement in Structural Engineers Association activities, I'm
currently mentoring a structural student, and I'm doing independent
research on using carbon fiber composites for dynamic applications (by
testing carbon fiber components in my race car - but it is legitimate).
I have had these activities pre-approved by the Oregon State Board.
Alaska now requires PDH's but I haven't set up any pre-approved
activities with them, yet. Also, you can pick up "free" PDH's from the
Simpson Strong Tie people as well as all the concrete anchor mfr's. who
are trying to get us to spec their products.

I have no objections to paying for PDH's. In fact the AISC prices are
very reasonable. But when the subject source of those PDH's is
presented to me, it would save my time to please advise that there is a
cost.

Sincerely,

Bob Garner

-----Original Message-----
From: t.w.allen@cox.net [mailto:t.w.allen@cox.net]
Sent: Friday, February 29, 2008 1:42 PM
To: seaint@seaint.org
Subject: RE: AISC eLearning

Just curious, Robert, but where can you get free PDHs?

For me, it is understood.

Regards,

T. William (Bill) Allen, S.E. (CA#2607)
Allen Designs
Consulting Structural Engineers
San Juan Capistrano, CA

---- "Garner wrote:
> While these are excellent resources and I greatly appreciate their
> presentation by AISC, I feel it would have been less misleading had
you
> said "They are free for anyone to watch, but there is a fee for
> obtaining pdh's............."
>
>
>
> As engineers, it is our responsibility to portray things honestly and
> objectively, and not to conceal information of which we are aware.
>
>
>
>
>
> Respectfully,
>
>
>
> Robert Garner, S.E.
>
>
>
> ________________________________
>
>
>
> From: Hewitt, Chris [mailto:hewitt@aisc.org]
> Sent: Friday, February 29, 2008 12:24 PM
> To: seaint@seaint.org
> Subject: AISC eLearning
>
>
>
> Hi,
>
>
>
> If you haven't had a chance to check it out yet, I would recommend
that
> members of this list have a look at AISC's new online educational
> programs at www.aisc.org/elearning <http://www.aisc.org/elearning> .
>
>
>
> They're all free for anyone to watch and are a great resource that you
> can take advantage of right from your desk or at home.
>
>
>
> This month we've released a "boxed lunch" presentation by Shankar Nair
> on the Stability Provisions of the AISC Specification, which I am sure
> is of interest to many structural engineers learning the new design
> specification. Dr. Nair is an excellent speaker and he was the winner
> of the 2007 AISC T.R. Higgins Lectureship Award for this work. The
> presentation gives an overview of stability design and also reviews
the
> Direct Analysis Method, which is a new approach to stability design
that
> allows engineers to design all of their frame columns with K = 1 when
> incorporating notional loads and reduced member stiffnesses into the
> design model.
>
>
>
> I hope that you find this to be a useful resource. If you have any
> questions, feel free to drop me a line.
>
>
>
> Chris
>
>
>
>
>
> Christopher M. Hewitt, S.E., LEED A.P.
>
> AISC Senior Engineer
>
>
>
>
>

--
T. William (Bill) Allen, S.E.
ALLEN DESIGNS
Consulting Structural Engineers

Have a kilo-mile day!
Bill Allen
2002 BMW R1150RT
San Juan Capistrano, CA
SouthCoast BMW Riders Club
BMW MOA #83869
IBA #24862

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

RE: AISC eLearning

Just curious, Robert, but where can you get free PDHs?

For me, it is understood.

Regards,

T. William (Bill) Allen, S.E. (CA#2607)
Allen Designs
Consulting Structural Engineers
San Juan Capistrano, CA

---- "Garner wrote:
> While these are excellent resources and I greatly appreciate their
> presentation by AISC, I feel it would have been less misleading had you
> said "They are free for anyone to watch, but there is a fee for
> obtaining pdh's............."
>
>
>
> As engineers, it is our responsibility to portray things honestly and
> objectively, and not to conceal information of which we are aware.
>
>
>
>
>
> Respectfully,
>
>
>
> Robert Garner, S.E.
>
>
>
> ________________________________
>
>
>
> From: Hewitt, Chris [mailto:hewitt@aisc.org]
> Sent: Friday, February 29, 2008 12:24 PM
> To: seaint@seaint.org
> Subject: AISC eLearning
>
>
>
> Hi,
>
>
>
> If you haven't had a chance to check it out yet, I would recommend that
> members of this list have a look at AISC's new online educational
> programs at www.aisc.org/elearning <http://www.aisc.org/elearning> .
>
>
>
> They're all free for anyone to watch and are a great resource that you
> can take advantage of right from your desk or at home.
>
>
>
> This month we've released a "boxed lunch" presentation by Shankar Nair
> on the Stability Provisions of the AISC Specification, which I am sure
> is of interest to many structural engineers learning the new design
> specification. Dr. Nair is an excellent speaker and he was the winner
> of the 2007 AISC T.R. Higgins Lectureship Award for this work. The
> presentation gives an overview of stability design and also reviews the
> Direct Analysis Method, which is a new approach to stability design that
> allows engineers to design all of their frame columns with K = 1 when
> incorporating notional loads and reduced member stiffnesses into the
> design model.
>
>
>
> I hope that you find this to be a useful resource. If you have any
> questions, feel free to drop me a line.
>
>
>
> Chris
>
>
>
>
>
> Christopher M. Hewitt, S.E., LEED A.P.
>
> AISC Senior Engineer
>
>
>
>
>

--
T. William (Bill) Allen, S.E.
ALLEN DESIGNS
Consulting Structural Engineers

Have a kilo-mile day!
Bill Allen
2002 BMW R1150RT
San Juan Capistrano, CA
SouthCoast BMW Riders Club
BMW MOA #83869
IBA #24862

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

Re: AISC eLearning

In a message dated 2/29/2008 1:25:35 PM Pacific Standard Time, rgarner@moffattnichol.com writes:

As engineers, it is our responsibility to portray things honestly and objectively, and not to conceal information of which we are aware.

Respectfully,

Robert Garner, S.E.

Robert

I know it is Friday..........I imangine it would take a case of beer to listen "honestly and objectively" to a Obama speech and not think he is the salvation for our country..........and the flood waters begin.

Joe Venuti
Johnson & Nielsen Associates
Palm Springs, CA

Delicious ideas to please the pickiest eaters. Watch the video on AOL Living.

RE: AISC eLearning

While these are excellent resources and I greatly appreciate their presentation by AISC, I feel it would have been less misleading had you said "They are free for anyone to watch, but there is a fee for obtaining pdh's............."

As engineers, it is our responsibility to portray things honestly and objectively, and not to conceal information of which we are aware.

Respectfully,

Robert Garner, S.E.

From: Hewitt, Chris [mailto:hewitt@aisc.org]
Sent: Friday, February 29, 2008 12:24 PM
To: seaint@seaint.org
Subject: AISC eLearning

Hi,

If you haven’t had a chance to check it out yet, I would recommend that members of this list have a look at AISC’s new online educational programs at www.aisc.org/elearning.

They’re all free for anyone to watch and are a great resource that you can take advantage of right from your desk or at home.

This month we’ve released a “boxed lunch” presentation by Shankar Nair on the Stability Provisions of the AISC Specification, which I am sure is of interest to many structural engineers learning the new design specification. Dr. Nair is an excellent speaker and he was the winner of the 2007 AISC T.R. Higgins Lectureship Award for this work. The presentation gives an overview of stability design and also reviews the Direct Analysis Method, which is a new approach to stability design that allows engineers to design all of their frame columns with K = 1 when incorporating notional loads and reduced member stiffnesses into the design model.

I hope that you find this to be a useful resource. If you have any questions, feel free to drop me a line.

Chris

Christopher M. Hewitt, S.E., LEED A.P.

AISC Senior Engineer

AISC eLearning

Hi,

If you haven’t had a chance to check it out yet, I would recommend that members of this list have a look at AISC’s new online educational programs at www.aisc.org/elearning.

They’re all free for anyone to watch and are a great resource that you can take advantage of right from your desk or at home.

I hope that you find this to be a useful resource. If you have any questions, feel free to drop me a line.

Chris

Christopher M. Hewitt, S.E., LEED A.P.

AISC Senior Engineer

Torsional Wind Load Cases

Hello all (Happy Friday),

In reference to the torsional wind load cases that are shown in ASCE 7-05, Figure 6-10 (p. 54, note #5), has anyone developed a feel for what building geometries or heights seem to really kick in a strong reaction to these effects, to where they control the design of certain portions? I'm trying to develop some intuitive knowledge of the effects of some of these load prescriptions.

Thanks,

Dave K. Adams, S.E., P.Eng.
LANE ENGINEERS, INC.
979 N. Blackstone Street

P.O. Box 1059
Tulare, CA 93275

Direct Line: (559) 688-5263

Direct FAX: (559) 688-8388

E-Mail: davea@laneengineers.com

Weblog: www.training4engineers.blogspot.com

Re: Sign Structures

Who gets hurt if the sign decides to be a wild wing?

Neil Moore, SE, SECB

At 09:15 AM 2/29/2008, you wrote:

A "dynamic" analysis for a billboard.... Tomfoolery at its highest...

On Fri, Feb 29, 2008 at 5:00 AM, Gary L. Hodgson and Assoc. <ghodgson@bellnet.ca> wrote:

Thanks, Harold

I will be doing that. There is no guidance in our codes on signs or

other non-building structures. Your codes go further than ours, as ours

are only written in regard to buildings. If I want to design a crane

runway, storage bin, or sign _for seismic loads_, I have to refer to

American publications. The problem is that our codes don't use the same

terms or geographical data.

In going up against this municipality, I have to be on firm footing,

because my customer has a history of bad relations with them--he has won

two law suits against the city and their three page letter (of

structural questions only) came two days after the latest judgement was

published in the newspaper. This city has the first or second highest

average income in Canada and they don't like billboard signs, even if

though there a lot of them existing in the city. One of the questions

was "did I do a dynamic analysis of the structure" (for a 20'x10' sign

with a top at 25' above grade).

Gary

How many cases of beer do I owe you now?

Harold Sprague wrote:

> Gary,

> The projected area in the plane of the sign is relatively small.

> Seismic may govern. You could categorize signs as nonbuilding

> structures. The loading is a function of the force resisting system

> which establishes the response coefficient and the mass.

>

> Regards,

> Harold Sprague

>

> > Date: Thu, 28 Feb 2008 17:04:42 -0500

> > From: ghodgson@bellnet.ca

> > To: seaint@seaint.org

> > Subject: Sign Structures

> >

> > List,

> > I design sign structures for 2 clients-these are all free-standing

> signs

> > on one or two posts. In our area, generally wind governs. A

> > municipality has questioned whether I designed a particular sign for

> > seismic loading. Nothing in our codes addresses the issue of signs

> > subject to seismic loading unless they are part of a building, in which

> > case they are considered a fixture just like a mechanical piece of

> > equipment. Our codes only require that signs over a certain height or

> > area have to be designed by a professional engineer. So, I guess my

> > question is what seismic loading do you design signs for? Thanks in

> > advance.

> > Gary

>

> ------------------------------------------------------------------------

> Need to know the score, the latest news, or you need your Hotmail®-get

> your "fix". Check it out. < http://www.msnmobilefix.com/Default.aspx>

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Re: Sign Structures

A "dynamic" analysis for a billboard.... Tomfoolery at its highest...

On Fri, Feb 29, 2008 at 5:00 AM, Gary L. Hodgson and Assoc. <ghodgson@bellnet.ca> wrote:

Thanks, Harold
I will be doing that. There is no guidance in our codes on signs or
other non-building structures. Your codes go further than ours, as ours
are only written in regard to buildings. If I want to design a crane
runway, storage bin, or sign _for seismic loads_, I have to refer to
American publications. The problem is that our codes don't use the same
terms or geographical data.
In going up against this municipality, I have to be on firm footing,
because my customer has a history of bad relations with them--he has won
two law suits against the city and their three page letter (of
structural questions only) came two days after the latest judgement was
published in the newspaper. This city has the first or second highest
average income in Canada and they don't like billboard signs, even if
though there a lot of them existing in the city. One of the questions
was "did I do a dynamic analysis of the structure" (for a 20'x10' sign
with a top at 25' above grade).
Gary
How many cases of beer do I owe you now?

Harold Sprague wrote:
> Gary,
> The projected area in the plane of the sign is relatively small.
> Seismic may govern. You could categorize signs as nonbuilding
> structures. The loading is a function of the force resisting system
> which establishes the response coefficient and the mass.
>
> Regards,
> Harold Sprague
>
> > Date: Thu, 28 Feb 2008 17:04:42 -0500
> > From: ghodgson@bellnet.ca
> > To: seaint@seaint.org
> > Subject: Sign Structures
> >
> > List,
> > I design sign structures for 2 clients-these are all free-standing
> signs
> > on one or two posts. In our area, generally wind governs. A
> > municipality has questioned whether I designed a particular sign for
> > seismic loading. Nothing in our codes addresses the issue of signs
> > subject to seismic loading unless they are part of a building, in which
> > case they are considered a fixture just like a mechanical piece of
> > equipment. Our codes only require that signs over a certain height or
> > area have to be designed by a professional engineer. So, I guess my
> > question is what seismic loading do you design signs for? Thanks in
> > advance.
> > Gary
>
> ------------------------------------------------------------------------
> Need to know the score, the latest news, or you need your Hotmail®-get

> your "fix". Check it out. <http://www.msnmobilefix.com/Default.aspx>

******* ****** ******* ******** ******* ******* ******* ***
* 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:
*
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--
David Topete, SE

re:hot weather concrete

My two cents on high temps and concrete is use ice. In your wall the concrete is going to be using up water so fast that consolidation is going to be a problem, you will probably end up with pockets all over the place and the different loads may even leave a seam where they don't bond. The material coming out of the trucks will be so dry that your contractor is going to be screaming for water and the end product will not look very good, even if they know how to use a vibrator. Strength of cylinder samples taken are probably going to pass your required strength, but the wall in reality will not be very good. (cylinder strength testing is just that, a minimum standard met in the job specs., longevity and durability values are not necessarily included in strength testing). On a slab it would be even worse, the top would dry out and give you cracking all over while the water below would be trapped, the contractor would have a terrible time screeding the slab and would probably be spraying water all over the place to allow them to finish the top. Might even look good until the top started coming off in a few weeks or months. Best bet is find some way to place the mud in the cool of the night, spray down the forms with a lot of water before placing the mud, and keep the sun off the area (especially rebar) also. I have an IBC special inspection card for reinforced concrete, as well as trying to learn what I can from the better contractors and suppliers, and have worked on a lot of summer time concrete jobs, and these are just factors that I have seen over and over.

ACI 305R "Hot Weather Concreting" recommends keeping concrete temperature as=
=20
low as possible in hot weather, and provides a long list of detrimental=20
effects due to hot weather and hot concrete. =20

I recall touring a nuclear power plant under construction west of Phoenix=20
several decades ago and being informed that 90% of the water in their mix wa=
s in=20
the form of ice. I assume there were good reasons to do that. =20

Ralph Hueston Kratz, S.E.
Richmond CA USA

In a message dated 2/27/08 4:41:21 PM, tiger@palaunet.com writes:
> All,
> I am hoping that someone on the listserver knows of literature that=20
> discusses the benefits of using crushed ice for concrete batching when sus=
tained=20
> ambient temperatures for both placement and curing are in the range of 95=20=
to 100=20
> degrees F.
> Let=E2=80=99s say I am placing concrete for two 8 inch precast walls (NOT=
mass=20
> concrete) in ambient temps of 95 to 100 deg F.
> I use one mix design, but in one batch I replace some of the water with=20
> crushed ice (no change in W/C ratio) resulting in the temp of the concrete=
at=20
> discharge being less than 90 deg F.=C2=A0 For the second batch I do not us=
e ice and=20
> so the concrete at discharge is 95 deg F or a bit above.=C2=A0 Both wall p=
anels=20
> are shaded and moisture cured in exactly the same fashion at the same ambi=
ent=20
> temperature of 95 to 100 deg F for 28 days.
> My question is, will the 28 day strength of the two panels differ=20
> significantly?
> =C2=A0
> Based on literature I have been able to dig up, it would seem that there=20
> are two major problem areas with regard to placing concrete at these temps=
.=C2=A0=20
> First would be the placement itself, as the hot weather would tend to redu=
ce=20
> workability and decrease set time.=C2=A0 It seems to me that the addition=20=
of ice=20
> would help in this area by lowering the concrete temp at discharge.
> Second problem area is overall decrease in ultimate concrete strength.=
=C2=A0=20
> Since the temp of the iced concrete would rise and match that of the unice=
d=20
> concrete within a few hours and stay at that level through almost all of t=
he=20
> curing time, it seems to me that there would likely NOT be a significant b=
enefit=20
> by adding ice in terms of 28 day concrete strength.
> =C2=A0
> I searched the listserver archives and didn=E2=80=99t come up with anythi=
ng on this=20
> topic.=C2=A0 I am trying to determine if it is necessary to use ice at all=
, since=20
> other methods such as the addition of plasticizers to ensure workability=20
> could be used to address the first problem area.=C2=A0 If, however, there=20=
is a=20
> noticeable effect on 28-day strength than keeping the ice requirement woul=
d be=20
> preferable.
> =C2=A0
> Thanks
> =C2=A0
> Terangue *Tiger* Gillham, PE
> GK2, Inc.
>=20
> tiger@palaunet.com <mailto:tiger@palaunet.com>
> =C2=A0

Kent T Golding
New Prison Construction-Oregon Department of Corrections
Deer Ridge Correctional Institution
541-475-4433 ext. 5206
541-475-4300 fax

The major difference between a thing that might go wrong and a thing that cannot possibly go wrong is that when a thing that cannot possibly go wrong goes wrong it usually turns out to be impossible to get at or repair

Re: butchering steel stud webs - guideline?

From page 5 of the SSMA Product Technical Information catalog, ICBO ER-4943P, punchouts have a maximum width of half the member depth or 2.5", whichever is less and a maximum length of 4.5". Minimum spacing is 24", minimum distance from end of stud to the near edge of the punch out is 10". Here's the link:

http://www.ssma.com/ssmatechcatalog.pdf

Hope this helps.

Wade Sticht, PE

On Fri, Feb 29, 2008 at 5:56 AM, Jerry Coombs <JCoombs@carollo.com> wrote:

I don't believe there is any prescriptive guideline.

For highly-loaded sluds, it likely needs to be calculated, which is why the Codes require a stamp for anything outside simple prescriptive "designs"

The design for how it is loaded is just like any other beam/ col. Relatively easy to calc the properties and design for the 5 psf load

However you CAN take, and justify, a relatively prescriptive approach. Look at your size/ gage of stud. measure the extent of the hole from "butchering. If the hole is no larger than the typical size of the hole in a punched stud, use the load table for punched. If the application works for the punched stud (very likely), it'll work fairly conservatively for your stud.

JDC

>>> On 2/28/2008 at 3:21 PM, "Haan, Scott M POA" <Scott.M.Haan@usace.army.mil> wrote:

Anyone aware of a prescriptive code requirement or SSMA guideline or
something for how much web can be butchered out interior partition steel
studs to get plumbing through?

******* ****** ******* ******** ******* ******* ******* ***
*   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:
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*   without your permission. Make sure you visit our web
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Re: Base Plate design

Just be careful in your design. Some authorities insist on using a rigid
plate method to design baseplates, others insist on using a flexible plate
approach. And each authority will claim the other is wrong. There is also
disagreement on how to do the flexible plate method, so you shouldn't
believe the first one you come across, which for structural steel is usually
the prying action discussion in the steel manual. (I am definitely
uncomfortable with using that method in certain situations, but that's my
opinion.)

Having done both, the flexible plate method is more conservative but
requires a lot more effort; and at times, results from the rigid plate
method was actually unconservative when compared to experimental evidence.

I don't recall which method Blodgett recommends as I haven't used it in a
long time, but when I was using it I found it to be unconservative also.

So do it with care and good judgment.

----Original Message Follows----
From: Andy Heigley <aheigley@jgaeng.com>
Reply-To: <seaint@seaint.org>
To: seaint@seaint.org
Subject: Re: Base Plate design
Date: Thu, 28 Feb 2008 09:49:30 -0500

I have the Blodgett book and the AISC Design
guide. Both references do not discuss a column base subjected to
Moment with uplift forces. (When i say uplift, i mean that the axial
force on the column is tension, or Pu = -60 K)

For instance, if my uplift is large in combination with a smaller
moment, there may not be any compression force on the baseplate. All
bolts will be in tension, but one side of the anchor rods will be in
higher tension loads than the other due to the moment.

Now, what if you have a large uplift, and a large moment, where you
have a little compression on the baseplate, etc.

With these conditions, i don't think that the the expression for 'Y'
(the length of plate in compression) is applicable.

I hope you can understand my question. if you need an example, how
would you design a baseplate for Pu= -60K with Mu = 130 k-ft?

Thanks for your responses...

Andy Heigley, PE

Micayas, Julius wrote:

Andy,

I got one
good reference for you from AISC
titled: Steel Design Guide Series
1

Column
Base Plate

By: John T.
DeWolf

Some
Practical Aspects of Column Base Selection

David T.
Ricker

This is a
publication combined issue by the
AISC and the Berlin Steel Company, Inc.

Engr. Julius
Micayas

P.E. license
no.32969

Project
Manager/Sr Lead
Structural engineer

River
Consulting LLC

111
Veterans Memorial Boulevard

Suite 1600

Metairie,
Louisiana
70005

Phone -
504-841-3014
(direct)

504 837-5275
(office)

Fax -
504-837-2986

E-mail: jmicayas@riverconsulting.com

W-page:

www.riverconsulting.com

From: Gary
Loomis [mailto:gloomis@MasterEngineersinc.com]

Sent: Thursday,
February 28, 2008
7:46 AM

To: seaint@seaint.org

Subject: RE: Base
Plate design

Yes,
Blodgett "Design of Welded
Structures" is probably one of the best. And it is relatively
cheap $10.00.

Gary W. Loomis, P.E.,
Senior Structural Engineering

Master Engineers and
Designers, Inc.

-----Original
Message-----

From: Andy Heigley
[mailto:aheigley@jgaeng.com]

Sent: Thursday,
February 28, 2008
8:30 AM

To: SEAINT

Subject: Base Plate
design

Hello all:

I'm looking for any references for designing column base plates where
the
column base is subjected to uplift and a large moment.

The AISC design guide does not discuss a column base with moment in
combination
with uplift.

Does anybody have any references for such a design?

Thanks in advance,

Andry Heigley, PE

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of Southern California (SEAOSC) server. To * subscribe (no fee) or
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Re: Sign Structures

Thanks, Harold
I will be doing that. There is no guidance in our codes on signs or
other non-building structures. Your codes go further than ours, as ours
are only written in regard to buildings. If I want to design a crane
runway, storage bin, or sign _for seismic loads_, I have to refer to
American publications. The problem is that our codes don't use the same
terms or geographical data.
In going up against this municipality, I have to be on firm footing,
because my customer has a history of bad relations with them--he has won
two law suits against the city and their three page letter (of
structural questions only) came two days after the latest judgement was
published in the newspaper. This city has the first or second highest
average income in Canada and they don't like billboard signs, even if
though there a lot of them existing in the city. One of the questions
was "did I do a dynamic analysis of the structure" (for a 20'x10' sign
with a top at 25' above grade).
Gary
How many cases of beer do I owe you now?

Harold Sprague wrote:
> Gary,
> The projected area in the plane of the sign is relatively small.
> Seismic may govern. You could categorize signs as nonbuilding
> structures. The loading is a function of the force resisting system
> which establishes the response coefficient and the mass.
>
> Regards,
> Harold Sprague
>
> > Date: Thu, 28 Feb 2008 17:04:42 -0500
> > From: ghodgson@bellnet.ca
> > To: seaint@seaint.org
> > Subject: Sign Structures
> >
> > List,
> > I design sign structures for 2 clients-these are all free-standing
> signs
> > on one or two posts. In our area, generally wind governs. A
> > municipality has questioned whether I designed a particular sign for
> > seismic loading. Nothing in our codes addresses the issue of signs
> > subject to seismic loading unless they are part of a building, in which
> > case they are considered a fixture just like a mechanical piece of
> > equipment. Our codes only require that signs over a certain height or
> > area have to be designed by a professional engineer. So, I guess my
> > question is what seismic loading do you design signs for? Thanks in
> > advance.
> > Gary
>
> ------------------------------------------------------------------------
> Need to know the score, the latest news, or you need your Hotmail®-get
> your "fix". Check it out. <http://www.msnmobilefix.com/Default.aspx>

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

Re: Other List Servers

Has anyone else had a problem getting registered there? I may have done something wrong the very first time I tried, and now it tells me that the name and email already exists and won't let me register. But it doesn't recognize me. Tried all of the logical approaches, and no response from the administrators.

JDC

>>> On 2/28/2008 at 9:27 PM, "erik gibbs" <erik.gibbs@gmail.com> wrote:

Try: http://www.eng-tips.com/

They have many different job categories from electrical to automotive engineering and many sub categories.

On Thu, Feb 28, 2008 at 2:27 PM, Wade Sticht, P.E. <wstichtpe@gmail.com> wrote:

As great as this list is, I'm wondering if anyone can recommend other engineering list servers, particularly those focusing on structural engineering or forensic investigations. Thanks.

Wade Sticht, PE

Re: butchering steel stud webs - guideline?

I don't believe there is any prescriptive guideline.

For highly-loaded sluds, it likely needs to be calculated, which is why the Codes require a stamp for anything outside simple prescriptive "designs"

The design for how it is loaded is just like any other beam/ col. Relatively easy to calc the properties and design for the 5 psf load

However you CAN take, and justify, a relatively prescriptive approach. Look at your size/ gage of stud. measure the extent of the hole from "butchering. If the hole is no larger than the typical size of the hole in a punched stud, use the load table for punched. If the application works for the punched stud (very likely), it'll work fairly conservatively for your stud.

JDC

>>> On 2/28/2008 at 3:21 PM, "Haan, Scott M POA" <Scott.M.Haan@usace.army.mil> wrote:

Anyone aware of a prescriptive code requirement or SSMA guideline or
something for how much web can be butchered out interior partition steel
studs to get plumbing through?

******* ****** ******* ******** ******* ******* ******* ***
*   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:
*
*   http://www.seaint.org/sealist1.asp
*
*   Questions to seaint-ad@seaint.org. Remember, any email you
*   send to the list is public domain and may be re-posted
*   without your permission. Make sure you visit our web
*   site at: http://www.seaint.org
******* ****** ****** ****** ******* ****** ****** ********

Thursday, February 28, 2008

Re: Strawbale Methods

I didn't catch what state the project is in, but California adopted its own
code for straw-bale construction that provides for load-bearing walls.
NOTE: The code may have been superseded; you can find it here:
http://www.leginfo.ca.gov/cgi-bin/waisgate?WAISdocID=26395320983+2+0+0&WAISaction=retrieve

If that doesn't work, go to http://www.leginfo.ca.gov/calaw.html, click the
"Health and Safety" checkbox, then enter 18944.30-18944.33 . That section
and 18944.40-18944.41 will get you started. I have no idea if these are
still current--supposedly the Building Standards Commission was supposed to
come up with something to go in the CBC. Won't THAT be wonderful.

Thor Matteson
www.shearwalls.com

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

RE: Topographic Effects

If ASCE7-05 clause 6.5.6.2 has similar intent to the Australian wind loading code AS1170.2. Then I believe the idea is to consider 8 compass directions ( N, NE, E, etc..) , each of these directions could have a different regional wind speed except in hurricane prone regions, where such directional variation is ignored for strength limit state at least. In addition the environment surrounding the building may differ: generating different wind speeds at the site, when account has been taken of exposure, topography and other factors such as shielding (ASCE7-5 not permitting).

Two orthogonal axes are determined for the building, though not relevant for a circular building. Then 45 degrees to either side of these axes (90 degree quadrant), the maximum wind speed from the cardinal directions (compass) occurring in the sector is the wind speed for that orthogonal direction. This may produce 4 different design wind speeds for the building. If wish to ignore the variations, then the maximum of all directions is the design wind speed for the building. Winds approaching from directions other than along the orthogonal axes may produce the worst effects and theses directions may also have to be considered. (For example 45 degrees to the free edge of a free standing wall, or is that the free edge to the wall of an open building?)

To AS1170.2 if consider directional wind speeds, the directionality factor turns the dominant regional wind speed into lower wind speeds for each compass direction. If adopt the maximum regional wind speed then there is a single directionality factor which accounts for the conservatism and allows some reduction like ASCE7.

If have different wind speeds flowing up the hill towards the buildings, and flowing down the hill towards the building, and choose to use the maximum of these wind speeds as the design wind speed, then the directionality factor kd in effect is doing the averaging for you: weighted average.

Since the research on topographical effects isn’t all that great, erring on the high side is preferable. I’ve had minor involvement with a project where:

1) Light weight water tank, comprising simple steel frame and polymer liner was picked up and thrown over the crest of the hill.

2) The swing doors opening out onto decking failing to stay closed, with driving rain getting in.

3) I think there was also mention of rain driven up through suspended timber floor.

Whilst some of this occurred during a storm (80km/h), it wasn’t any where near the regional design wind speed (162km/h) and the weather proofing problem occurring at even lower wind speeds. As a consequence of this project the tank manufacturer is now getting his tanks engineered though of a size not normally requiring approval. Whilst the builder is now paying more attention to the wind class requirements for windows and making sure supplier can provide to suit, and no longer believes wind is not an issue. (For residential we have a simplified wind classification system AS4055. Having calculated wind speed to AS1170.2, the site can be assigned a wind class, which assigns a design wind speed which is usually much greater than that from AS1170.2: most sites at lower end of the class. {N1 to N6 non-cyclonic, and C1 to C4 cyclonic. Knowing the site is wind class N3 the builder can order windows to suit: assuming the builder and window supplier understand. Timber framing and trusses also ordered on this basis. Timber estimators can determine the wind class symbolically: Region A/TC3/T2/NS = N3, they just look the combination up in a table.)

Regards

Conrad Harrison

B.Tech (mfg & mech), MIIE, gradTIEAust

mailto:sch.tectonic@bigpond.com

Adelaide

South Australia

Re: Other List Servers

Try: http://www.eng-tips.com/

They have many different job categories from electrical to automotive engineering and many sub categories.

On Thu, Feb 28, 2008 at 2:27 PM, Wade Sticht, P.E. <wstichtpe@gmail.com> wrote:

As great as this list is, I'm wondering if anyone can recommend other engineering list servers, particularly those focusing on structural engineering or forensic investigations. Thanks.

Wade Sticht, PE

Re: Topographic Effects

naturally, I would use the higher (hence conservative) value...

On Thu, Feb 28, 2008 at 2:58 PM, <Jnapd@aol.com> wrote:

Dave and others

The revised conditions.........would you average the 1.74 & 2.03 since each is correct for a 90 quadrant behind the house ??

the house is at 1000' with another 560' above (at 45 deg), then Lh = 780' That would change up the numbers a bit.

H/Lh = 1560/780 = .5

K1 = 0.43 (2D escarpment)
K2 = 0.79 for x/Lh = 560'/780'= 0.718
K3 = 0.94 for z/Lh = 22'/780' = 0.0282

Kzt = (1+K1K2K3)^2 = 1.74 1.99

the house is at 1000' with another 60' above (at 45 deg), then Lh = 530' That would change up the numbers a bit.

H/Lh = 1060/530 = .5
K1 = 0.53 (3D Hill)
K2 = 0.93 for x/Lh = 60'/530' = 0.1132

K3 = 0.86 for z/Lh = 22'/530' = 0.0415

Kzt = (1+K1*K2*K3)^2 = 2.03 2.3

Joe Venuti
Johnson & Nielsen Associates
Palm Springs, CA

Delicious ideas to please the pickiest eaters. Watch the video on AOL Living.

--
David Topete, SE