Structural Engineering: 2009-10-11

Saturday, October 17, 2009

Re: Readability

... or simply use the Opera browser which is able to strip off visual styles from any given page.

On Sat, Oct 17, 2009 at 6:26 PM, G Vishwanath <gvshwnth@yahoo.com> wrote:

I am reproducing below a posting of mine on some other lists/forums (cultural and community related) where I am an active member these days. I thought this should be shared with all of you too.

Regards

Vish

=========

Sincere and grateful thanks to Sri K Raman for sharing an extremely useful link with us.

This is one link that is going to be extremely useful to Oldies like us.

The youngsters may not bother too much with this.

I feel compelled to dwell on this a little more in detail than Sri Raman has done in his short and crisp mail.

I also am unable to control my urge to share it with friends in several other fourms where I am a member.

On an avergage web page, I too, like Sri Raman, have been distracted too often with the garland of ads, thumbnails, options, links, etc around the main content which is what I am focusing on while reading. This main readable content sometime occupies less than half of the screen real estate.

This simple tool shared by Sri Raman, without having to install any software, has enabled me to discard all the extraneous stuff around the main content and enlarge the text to fill the entire space available and make it far easier to read.

For those who missed the link, or who ignored it, not realising its value, here it is once again.

http://lab.arc90.com/experiments/readability/

When you copy this link into your browser window and hit Enter, the Readability page opens up.

From among the options I found the following to yeild the best results (for me at least) after some trial and error.

I chose :
Style: Terminal
Size: Medium
Margin : Narrow

Afterwards simply right click on "Readability" and Choose "Add to Favorites"
This will permanently add Readability to your list of favorite web sites.
This procedure is necessary only once.

Next time you see a web page, with a lot of clutter around it, and want to focus on the main article in simple plain text with less scrolling and less eyestrain, even as the web page of interest is open, Choose "Readability" from the list of favorites.

The screen is quickly transformed and you can read far more easily as the text content fills up the page and the text is greatly enlarged. The ads, links, thumbnails extra simply vanish.

There is an option to revert to the original layout with just a click.

While Sri Raman has been kind to share this with us, many may not have realized the true value of this simple tool so I thought I should pitch in and share my experience of using this handy and nifty tool.

I exhort all oldies like me to try it out.

Since I am only 60, my option of "Medium" was a nice compromise between readable text size and the need to scroll down more frequently. For everyone's info, I have a special pair of spectacles designed for working on computers. The lens is powered to give the best focus for my eyes for a two feet distance. I now sit back in my chair and relax while I read. I don't have to sit hunched over.

When I cross 70 I will choose "large". If I live to cross 80 I may like to choose Extra Large. The letters appear like mini headlines and you can read them from yards away!

How I wish there was a similar tool "Viewability" for watching TV programs! One that cuts out all the ads and presents only the program.

For good measure, how about another tool called "Listenability" that enables me to listen to good stuff on FM Radio, with all the stupid ads and the immature and idle talk of disc jockeys cut out!

And Yes I know what some my friends on these lists are thinking.

Howabout a tool that cuts down on the length of my mails and eliminates verbosity and presents the gist in just a few lines.

But I am too greedy! Let me content myself for now with this tool that Sri K Raman has shared with all of us.

Thanks once again to Sri Raman, and I will look upon this as a nice Deepwali gift from a fellow member.

Regards to all
G Vishwanath

Bangalore

--
Alexander Bausk
Civil/Structural design & inspection engineer, CAD professional
http://bausk.wordpress.com
ONILAES Lab at PSACEA
Dnipropetrovsk, Ukraine
Tel. +38 068 4079692
Fax. +38 0562 470263
bauskas@gmail.com

re: stadium loads

Pretty cool stuff, you guys definitely have something to jump up and down about. At least one ACC team is holding it down. I am not sure I am a full believer of Miami yet. My deep and utter hatred of UM has something to do with that.

I have said this before to people, it is so funny what they will play at stadiums on the PA or by the marching bands now. Metallica was vilified when they first came out much like AC/DC and Black Sabbath, by ultra conservatives looking at someone to blame for their children being so “bad”. Sure the bands play the part of being a bit on the dark or evil side, but it is such an act. Look at Ozzy now with his family reality show… Just funny how 10-15 years will cause a generational shift. You now here marching bands playing Crazy Train!

I heard an interview last night with Brian Johnson of AC/DC and he said half the time he was just trying to find words that rhymed, flowed, and sounded cool. That last thing he was thinking about is if you play the record backwards you can hear the devil…

Stadium action can get crazy, and the density can be pretty high.

Virginia Tech's football intro involves most of the student jumping (somewhat in rhythm, as limited by BAC) to "Enter Sandman," by Metallica. This video http://www.youtube.com/watch?v=zPQkvLWWaUE from 0:40 to 0:45 shows the metal endzone stands. I sit in the old farts section, on concrete, and can still feel the vibration of the system during the intro.

Jordan

Friday, October 16, 2009

Re: floor LL for a club - stadium action

Stadium action can get crazy, and the density can be pretty high.
Virginia Tech's football intro involves most of the student jumping
(somewhat in rhythm, as limited by BAC) to "Enter Sandman," by
Metallica. This video http://www.youtube.com/watch?v=zPQkvLWWaUE from
0:40 to 0:45 shows the metal endzone stands. I sit in the old farts
section, on concrete, and can still feel the vibration of the system
during the intro.

Jordan

akester@cfl.rr.com wrote:
> <snip> Reminds me of before the 4th quarter of Wisconsin Badger football games they play a song where all the fans jump up and down in unison. They said on ESPN once that the engineering department did a study to make sure everything was "structurally sound" and could handle the vibrations and impact loads. I understand they have a good engineering dept so I would rest easy cheeseheads. Being a Florida State alumnus at the moment there is no fear of anyone jumping up and down in unison at our stadium, and I don't think groans of disappointment can affect a structure.
>
> Everyone have a good weekend,
> Andrew Kester, PE

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re: floor LL for a club

Ken,
Although I am well past my clubbing days, if there ever were any, I did just go to a few clubs at Islands of Adventure City Walk in Orlando for my girlfriend's birthday. (We decided we are too old for going to clubs after that.) I assure you, nobody is doing disco moves, if that is your frame of reference you would not want to know what they are up to now.

Anyway, I think I may add a little to that load. You never know what they are going to do at that club. I can see a special event, live show, etc. where people are really packed in there and could exceed 100psf. Although, with duration factors and what not, you are probably ok. I may personally go 125psf or so, that is just a judgment/gut call though. Also, most importantly I think with a wood framed structure supporting live load, is deflection or "flex". Just like when I design a deck or similar structure I assure the deflection is very tight to avoid "occupant discomfort". Others already spoke about vibration but I may be worried about that too. Since you are upgrading an existing structure, I would be most concerned about connections.

I was watching a special on Discovery or something about soccer stadium construction. After a major collapse in the early 1900s in England, they built a mock-up of stands and with engineers watching and taking notes they recruited a few hundred fans to march in footstep, stand up and sit down on cue, jump up and down, get up stand up come on throw your hands up.... Reminds me of before the 4th quarter of Wisconsin Badger football games they play a song where all the fans jump up and down in unison. They said on ESPN once that the engineering department did a study to make sure everything was "structurally sound" and could handle the vibrations and impact loads. I understand they have a good engineering dept so I would rest easy cheeseheads. Being a Florida State alumnus at the moment there is no fear of anyone jumping up and down in unison at our stadium, and I don't think groans of disappointment can affect a structure.

Everyone have a good weekend,
Andrew Kester, PE

Thursday, October 15, 2009

Re: seaint Digest for 14 Oct 2009

You're probably thinking of Dr. Tom Murray, also at Tech, who had done a lot of research in floor vibrations (and has a commercial program for floor evaluation, or did several years ago). Dr. Woeste is a wood guy - and a very good one, at that - but not into steel vibrations. Both are officially retired, I believe, though old engineers never really retire - they just consult at a higher rate. :-)

Jordan

Ted wrote:

Have you seen this story out of Va. Tech, Ken? It refers to a floor issue brought to light by Mary Kay cosmetics sales people doing the bunny hop in Charlotte. The load was not just live, but in phase, to the extent those folks have rhythm ... Va Tech has done some deep study of floor vibration — Frank Woeste, prof. emeritus, was the pivot man on that work, if I understand correctly, but he may be semi-retired these days. I gather it can get complicated.

[the article] http://www.arch.virginia.edu/~km6e/arch721/docs/enr-annoying-floors.pdf

-- Ted Cushman

tedcushman@gmail.com

-->On Oct 15, 2009, at 12:00 AM, admin wrote:

From: ken ng <zy7up@yahoo.com>
Subject: Wood frame dancing floor
To: seaint@seaint.org

I have a project and it's required to upgrade the existing wood floor framing with the live load capacity of 40 psf. The wood floor will be used as a night club dance floor. I was planning to use 100 psf live load. I was wondering if I should include the live load impact to the floor to handle large groups of dancers. I don't know what type music the night club will play. Since the site is located within a university school zone. What type of music are young adults dancing to now a day? Saturday Night Fever? <--

Re: seaint Digest for 14 Oct 2009

Have you seen this story out of Va. Tech, Ken? It refers to a floor issue brought to light by Mary Kay cosmetics sales people doing the bunny hop in Charlotte. The load was not just live, but in phase, to the extent those folks have rhythm ... Va Tech has done some deep study of floor vibration — Frank Woeste, prof. emeritus, was the pivot man on that work, if I understand correctly, but he may be semi-retired these days. I gather it can get complicated.

[the article] http://www.arch.virginia.edu/~km6e/arch721/docs/enr-annoying-floors.pdf

-- Ted Cushman

tedcushman@gmail.com

-->On Oct 15, 2009, at 12:00 AM, admin wrote:

From: ken ng <zy7up@yahoo.com>
Subject: Wood frame dancing floor
To: seaint@seaint.org

I have a project and it's required to upgrade the existing wood floor framing with the live load capacity of 40 psf. The wood floor will be used as a night club dance floor. I was planning to use 100 psf live load. I was wondering if I should include the live load impact to the floor to handle large groups of dancers. I don't know what type music the night club will play. Since the site is located within a university school zone. What type of music are young adults dancing to now a day? Saturday Night Fever? <--

Re: Wood frame dancing floor

Yes, 100psf is the correct design. In the case of a wood floor, you'll find that the forces are likely a wash - most impacts from human activity do not exceed 2x the static load, which is (coincidentally) the impact duration factor for wood. Swingsets, by the way, are in the same class - though I've only ever been asked to check one of them. The force at the bottom of a swing is twice the static load of the occupant, if memory serves.

Jordan

ken ng wrote:

I have a project and it's required to upgrade the existing wood floor framing with the live load capacity of 40 psf. The wood floor will be used as a night club dance floor. I was planning to use 100 psf live load. I was wondering if I should include the live load impact to the floor to handle large groups of dancers. I don't know what type music the night club will play. Since the site is located within a university school zone. What type of music are young adults dancing to now a day? Saturday Night Fever?

Re: Wood frame dancing floor

Ken Ng wrote, “…Since the site is located within a university school zone. What type of music are young adults dancing to now a day? Saturday Night Fever?”

Ken,

I did one of these – renovation of a wood-framed building for second floor night club and dancing – 20 years ago. It was 100 psf then, and IBC 2009 still says 100 psf for dance halls and ballrooms. It has changed hands at least 2-3 times since then, so my only real recommendation is not to base your design on what is happening now.

HTH,

Jim Getaz

Not usually a wood-frame engineer

Wednesday, October 14, 2009

Wood frame dancing floor

I have a project and it's required to upgrade the existing wood floor framing with the live load capacity of 40 psf. The wood floor will be used as a night club dance floor. I was planning to use 100 psf live load. I was wondering if I should include the live load impact to the floor to handle large groups of dancers. I don't know what type music the night club will play. Since the site is located within a university school zone. What type of music are young adults dancing to now a day? Saturday Night Fever?

Tuesday, October 13, 2009

Re: Mr. Polhemus Gets A Job

Harold Sprague wrote:

Bill,

Congratulations!!
This calls for a beer!

In honor of the upcoming holiday season:

http://www.youtube.com/watch?v=l2oPio60mK4

Re: Mr. Polhemus Gets A Job

Harold Sprague wrote:

Bill,

Congratulations!!
This calls for a beer!

Harold, IIRC, with you EVERYTHING calls for a beer. My dog had a litter of puppies. The Eastern and Russian Orthodox Churches are merging. The star Aldebaran is being occulted by the moon tonight. The spring rains have started (somewhere).

What's your answer? Same as that of the McKenzie Brothers: BEER.

(Uh, not that there's anything wrong with that).

RE: Mr. Polhemus Gets A Job

Bill,

Congratulations!!
This calls for a beer!

Regards, Harold Sprague

Date: Tue, 13 Oct 2009 14:25:30 -0500
From: bill@polhemus.cc
To: seaint@seaint.org
Subject: Mr. Polhemus Gets A Job

I am now employed (as of 26 October, anyway).

I'm lovin' it.

Hotmail: Free, trusted and rich email service. Get it now.

Re: Mr. Polhemus Gets A Job

Congratulations, Bill.

Would you give some details?

P.s. Um, does that sound like I actually requested some bolts and other small hardware?

On Tue, Oct 13, 2009 at 10:34 PM, Daryl Richardson <h.d.richardson@shaw.ca> wrote:

Bill,

That is great news!!

Regards,

H. Daryl Richardson

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

From: Bill Polhemus

To: seaint@seaint.org

Sent: Tuesday, October 13, 2009 1:25 PM

Subject: Mr. Polhemus Gets A Job

I am now employed (as of 26 October, anyway).

I'm lovin' it.
******* ****** ******* ******** ******* ******* ******* *** * 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 ******* ****** ****** ****** ******* ****** ****** ********

Re: Structural Engineering Online Encyclopedia

Michel Blangy wrote:
> Mr. White has my vote for the Nobel prize in Structural Engineering.
>
Wait, he's only been out of college for twelve days...

Oh. Never mind.

Re: Mr. Polhemus Gets A Job

Richard Calvert wrote:

Congratulations bill!

(it must be a sign that the economy IS actually turning around if even bill can get a job!)

The weird (and kinda wonderful) thing is, the economy ISN'T turning around. This is a tremendous blessing, and can't be viewed any other way by me at least. I am humbled and quite grateful.

Re: Anyone using freeware FEA?

Fugeeo,

I used the Windows version. I'm not aware of any difference between that one and the Linux version.

In reply to your information, there are indeed cheap analysis programs that do their job good.

Perphaps you'd be also interested in Roshaz - it is a ~500 bucks worth pre/postprocessor for CalculiX (its existence proves that

Calculix pre/post is awful).

Actually, to dream a bit, I seek a good investment for my time to program some kind of hand-tailored software that

would be of use for engineers and would be extensible with user-written design/check routines.

By good investement, I mean an open-source solver not bound by licensing and therefore not a black-box solution or under risk of

developer ceasing license/support renewal.

I currently looking towards CalculiX as a tested engine but the problem with beam elements needs more research.

To dream a bit more, an ideal FEA software would have a Robot SA-like user interface, a nonlinear, 3D, substructure-enabled, efficient (~1m DOF?) solver

and user-written, highly customisable design modules, all that available to public in source codes.

Remember that user-written design modules would greatly benefit to the international engineering community, producing kind of a common denominator

to compare national codes, projects, share design models etc. Doing that within proprietary software scope always restricts the audience to specific software users.

I have a parable for that. In my childhood, I had a (Soviet) book about weapons history. It described the situation preceding the invention of a tank in WWI as

that all the components of it - engine, tracks, gun, armor steel - were already available separately; the invention was to combine them into one unit.

P.s. To correct myself, CalculiX is not an offspring of Plaxis at all. Instead, it reads Abaqus code.

On Tue, Oct 13, 2009 at 8:08 PM, Fugeeo <fugeeo@edoors.com> wrote:

Alexander, did you try the Window's version of Calculix? Or only the Linux
version?

I have been learning ADINA 900 nodes. It's $140.00, and you also receive
the finite element analysis book by Bathe (in itself worth $140.00). I find
the user interface to be very cumbersome, however, it can use input from
ANSYS files. I think it would be interesting to use a program like Calculix
to preprocess... and then use the ADINA for the analysis, it is a commercial
software, and highly tested. 900 nodes is pretty good for many things we do
in structural design.

ADINA staff are very personable.

1. CalculiX.Good: Frequently updated, kind of an offspring of the renowned
Plaxis (?). Has some user-to-user support. Lots and lots of features
including large displacements, nonlinear material, etc.
> Bad: pre/post is total hell. Not because it's strange, it really is
very uncomfortable. You have to operate some weird named groups, etc.Also,
it 'inflates' beam elements (that usually have a precise analytic
solution) to form 3D 20-node solids which in turn causes problems with
torsion calculations, hollow sections etc.
> Resume: really needs a good pre/postprocessor (I'm going to write one
when I'm out of work and so become rich and famous) and some workarounds
for problems with beam elements.

Re: Mr. Polhemus Gets A Job

Bill,

That is great news!!

Regards,

H. Daryl Richardson

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

From: Bill Polhemus

To: seaint@seaint.org

Sent: Tuesday, October 13, 2009 1:25 PM

Subject: Mr. Polhemus Gets A Job

I am now employed (as of 26 October, anyway).

I'm lovin' it.
******* ****** ******* ******** ******* ******* ******* *** * 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 ******* ****** ****** ****** ******* ****** ****** ********

RE: Mr. Polhemus Gets A Job

Congratulations bill!

(it must be a sign that the economy IS actually turning around if even bill can get a job!)

From: Bill Polhemus [mailto:bill@polhemus.cc]
Sent: Tuesday, October 13, 2009 3:26 PM
To: seaint@seaint.org
Subject: Mr. Polhemus Gets A Job

I am now employed (as of 26 October, anyway).

I'm lovin' it.

Mr. Polhemus Gets A Job

I am now employed (as of 26 October, anyway).

I'm lovin' it.

RE: Mr. Polhemus Gets A Job

Wow…that’s a nice gig.

Well done, Bill.

David L. Fisher SE PE

Senior Principal

Fisher and Partners

372 West Ontario

Suite 301

Chicago 60654

312.622.0409 (m)

312.573.1701

312.573.1726 (f)

www.fpse.com

-----Original Message-----
From: Bill Polhemus [mailto:bill@polhemus.cc]
Sent: Tuesday, October 13, 2009 2:26 PM
To: seaint@seaint.org
Subject: Mr. Polhemus Gets A Job

I am now employed (as of 26 October, anyway).

I'm lovin' it.

Re: Anyone using freeware FEA?

Alexander, did you try the Window's version of Calculix? Or only the Linux
version?

I have been learning ADINA 900 nodes. It's $140.00, and you also receive
the finite element analysis book by Bathe (in itself worth $140.00). I find
the user interface to be very cumbersome, however, it can use input from
ANSYS files. I think it would be interesting to use a program like Calculix
to preprocess... and then use the ADINA for the analysis, it is a commercial
software, and highly tested. 900 nodes is pretty good for many things we do
in structural design.

ADINA staff are very personable.

1. CalculiX.Good: Frequently updated, kind of an offspring of the renowned
Plaxis (?). Has some user-to-user support. Lots and lots of features
including large displacements, nonlinear material, etc.
> Bad: pre/post is total hell. Not because it's strange, it really is
very uncomfortable. You have to operate some weird named groups, etc.Also,
it 'inflates' beam elements (that usually have a precise analytic
solution) to form 3D 20-node solids which in turn causes problems with
torsion calculations, hollow sections etc.
> Resume: really needs a good pre/postprocessor (I'm going to write one
when I'm out of work and so become rich and famous) and some workarounds
for problems with beam elements.

Monday, October 12, 2009

RE: Shear Failure of shallow foundation

Yes got 4 copies.

Also posted my guess in answer to the question asked.

My guess was based on design of punches for sheet metal work, not quite the
same: as involves punch and die, along with clamp, and dependent on
clearance between die and punch. If clearance equals thickness of sheet
metal then have potential for bending and deep drawing, slightly less then
get ironing which helps sets the form and reduce spring back. There has to
be very fine clearance to actually punch a hole through the sheet metal and
relatively high clamp force on the sheet. For deep drawing a low clamp force
is required to prevent buckling and wrinkling of the sheet, yet still allow
material flow into the die.

If the conditions are right for punching, then a crack propagates ahead of
the punch. Typically the punch penetrates about 2/3 rds of the depth
producing a smooth surface, and the crack propagates the last 1/3 rd
producing a rough crystalline facture surface, at 45 degrees, which
depending on application may or may not then require reaming to remove.
Since the fracture plane is undesirable some effort is taken to limit to the
1/3rd depth. But getting it right is a lot more art than science.

In any case my rough answer is that a 45 degree failure plane less than the
depth of the concrete slab away from face of column, would partly cut the
column, thus the shear plane is not entirely in the slab. For punching,
expect some penetration of the column into the slab, and a facture plane to
start to propagate at some depth into the slab, say half the depth of the
slab and still 45 degrees.

But without the die and clamp, likely to get a lot more bending and
stretching of the slab, than pure shear. Also foundation suggests support
by the ground below, so to punch column through slab have to displace soil
below.

But as I say, just a guess since not all that familiar with concrete design.
So may be someone more familiar with concrete can provide a more suitable
explanation.

Regards
Conrad Harrison
B.Tech (mfg & mech), MIIE, gradTIEAust
mailto:sch.tectonic@bigpond.com
Adelaide
South Australia

RE: Structural Engineering Online Encyclopedia

Mr. White has my vote for the Nobel prize in Structural Engineering.

> I am currently working on a beta project for an online collaborative
> encyclopedia based on the wiki platform.

RE: StructuralPedia - Main Wind Force vs C&C Wind Force

Thanks Jeremy,

I will provide an entry to structural wiki soon. In the interim, a batten is
simply a member typically on flat. For timber framing our code refers to
roof battens and ceiling battens. There are also some cold-formed steel
sections, similar to top hats but flatter, also called roof battens and
ceiling battens. Also for solid brick, tend to fasten timber battens on flat
to the wall to attach plaster board to.

If not on flat then more generally refer to as roof purlins and wall girts.

Regards
Conrad Harrison
B.Tech (mfg & mech), MIIE, gradTIEAust
mailto:sch.tectonic@bigpond.com
Adelaide
South Australia

RE: Low alkali cement

Kevin,
That is a very good observation and cautionary tale. I have had major problems with reactive aggregate on a project that can not be discussed in an open forum. A non AAR mix is preferable to control costs. Give the contractors the latitude to either use different aggregate or mitigating the mix. Fly ash mixes and lithiums are commonly used and effective.

The newer testing procedures only take about 16 days. If your testing lab has experience, they will develop several possible mixes at one time. They will need at least 28 days for the confirmation cylinders for a regular mix design submittal anyway. The time for testing for the reactive aggregate should not be an issue.

I would suggest that you also get a petrographic analysis of the aggregate. This gives some additional information, but costs a bit more. ASR is relatively easy to predict an mitigate. ACR is much more problematic.

I am a bit curious about being dismissive about slabs on ground. That is where it is generally the worst. Paving in particular drives the necessity for mitigation. The source for the water can be from wash downs for from the ground. Even atmospheric water vapor can be a problem. Texas, New Mexico and California have all had serious problems with reactive aggregate in relatively arid regions.

A good resource for reactive aggregate in building construction is Dr. Doug Hooton of the University of Toronto.

Regards, Harold Sprague

Date: Mon, 12 Oct 2009 14:53:37 -0400
Subject: Re: Low alkali cement
From: kbofoz@gmail.com
To: seaint@seaint.org; structous@douglasconsultants.ca

I'm far behind in my messages, but this is an interesting subject, and important here in Quebec, where there are AAR problems (RAG in French).

In reaction to this reaction, I started by specifying non-AAR aggregates, to be demonstrated by the concrete supplier. All the goof local suppliers have done the appropriate testing on their aggregates, so there is no extra cost for the testing.
However, this generally meant that only granitic aggregates could be used, at a higher cost.
Discussions with our tech lab led to our specifying a non-AAR mix, as opposed to a non-AAR aggregate. This generally costs no extra. Again, testing is required, but has usually already been done and documented adequately.
They also pointed out that only concrete that is in contact with the earth or frequently wet is subject to the problem, except that research has shown that there have never been problems with a slab-on-ground.
So now we specify that mixes must be non-AAR for footings, foundation walls, and exterior concrete.
However, as discussed in that extraordinary book The Black Swan (which all engineers should read), absence of proof is not proof of absence. So one day maybe we will discover a SOG that also has the problem, but for the moment, we do not require non-AAR mixes for SOGs.

On Thu, Feb 19, 2009 at 5:30 PM, Dickey, David <David.Dickey@masonandhanger.com> wrote:

When specifying the type of portland cement to be used in a concrete mix, do you specify low alkali cement?

Do you specify it on all of your projects? Or none or your projects?

Is there data available that shows areas of the country with siliceous aggregates that could contribute to alkali-silica reaction?

How much more does low alkali cement cost?

Is the testing that can be specified to determine the alkali-aggregate reactivity, ASTM C1260, something that is routinely done by the concrete supplier that can be requested, or would the testing be a significant additional cost to the project?

Thanks,

David Dickey, PE

Lexington, KY

Hotmail: Trusted email with Microsoft's powerful SPAM protection. Sign up now.

RE: Shear Failure of shallow foundation

I didn't

From: Daryl Richardson [mailto:h.d.richardson@shaw.ca]
Sent: Monday, October 12, 2009 2:06 PM
To: seaint@seaint.org
Subject: Re: Shear Failure of shallow foundation

Fellow engineers,

I got four(4) copies of this. Did others have the same experience?

Regards,

H. Daryl Richardson

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

From: Mandeep Singh

To: seaint@seaint.org

Sent: Sunday, October 11, 2009 10:34 PM

Subject: Shear Failure of shallow foundation

Hi all,

Can anyone tell the reason behind the codal provision of taking the critical section for failure of foundation in shear at a distance of d/2( d=thickness of foundation slab) from the face of column for punching shear and at distance of d in case of one way shear.

Thanks & Regards.

Mandeep Singh

GET

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Re: Low alkali cement

I'm far behind in my messages, but this is an interesting subject, and important here in Quebec, where there are AAR problems (RAG in French).

In reaction to this reaction, I started by specifying non-AAR aggregates, to be demonstrated by the concrete supplier. All the goof local suppliers have done the appropriate testing on their aggregates, so there is no extra cost for the testing.
However, this generally meant that only granitic aggregates could be used, at a higher cost.
Discussions with our tech lab led to our specifying a non-AAR mix, as opposed to a non-AAR aggregate. This generally costs no extra. Again, testing is required, but has usually already been done and documented adequately.
They also pointed out that only concrete that is in contact with the earth or frequently wet is subject to the problem, except that research has shown that there have never been problems with a slab-on-ground.
So now we specify that mixes must be non-AAR for footings, foundation walls, and exterior concrete.
However, as discussed in that extraordinary book The Black Swan (which all engineers should read), absence of proof is not proof of absence. So one day maybe we will discover a SOG that also has the problem, but for the moment, we do not require non-AAR mixes for SOGs.

On Thu, Feb 19, 2009 at 5:30 PM, Dickey, David <David.Dickey@masonandhanger.com> wrote:

When specifying the type of portland cement to be used in a concrete mix, do you specify low alkali cement?

Do you specify it on all of your projects? Or none or your projects?

Is there data available that shows areas of the country with siliceous aggregates that could contribute to alkali-silica reaction?

How much more does low alkali cement cost?

Is the testing that can be specified to determine the alkali-aggregate reactivity, ASTM C1260, something that is routinely done by the concrete supplier that can be requested, or would the testing be a significant additional cost to the project?

Thanks,

David Dickey, PE

Lexington, KY

RE: Shear Failure of shallow foundation

Yes

D. Matthew Stuart, P.E., S.E., F.ASCE, SECB

Senior Project Manager

Structural Department

Associate

Engineers and Consultants - CMX

200 Route 9

Manalapan, NJ 07726

732-577-9000 (Ext. 308)

908-309-8657 (Cell)

732-298-9441 (Fax)

mstuart@CMXEngineering.com

From: Daryl Richardson [mailto:h.d.richardson@shaw.ca]
Sent: Monday, October 12, 2009 2:06 PM
To: seaint@seaint.org
Subject: Re: Shear Failure of shallow foundation

Fellow engineers,

I got four(4) copies of this. Did others have the same experience?

Regards,

H. Daryl Richardson

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

From: Mandeep Singh

To: seaint@seaint.org

Sent: Sunday, October 11, 2009 10:34 PM

Subject: Shear Failure of shallow foundation

Hi all,

Can anyone tell the reason behind the codal provision of taking the critical section for failure of foundation in shear at a distance of d/2( d=thickness of foundation slab) from the face of column for punching shear and at distance of d in case of one way shear.

Thanks & Regards.

Mandeep Singh

GET

E–¶§Ãj¢–²ŠjjžÊ‰®º°¡¶¡º®–®HH®Nn‰¡¢Jrzj¢¶ÿ±žƒj·¥²ž±ž±žzz—±¶z¶¹qjÉzµŠºº®²1²ÊŠ¢yµ†ÿÂŠ

Re: Shear Failure of shallow foundation

Fellow engineers,

I got four(4) copies of this. Did others have the same experience?

Regards,

H. Daryl Richardson

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

From: Mandeep Singh

To: seaint@seaint.org

Sent: Sunday, October 11, 2009 10:34 PM

Subject: Shear Failure of shallow foundation

Hi all,
Can anyone tell the reason behind the codal provision of taking the critical section for failure of foundation in shear at a distance of d/2( d=thickness of foundation slab) from the face of column for punching shear and at distance of d in case of one way shear.

Thanks & Regards.

Mandeep Singh

GET
E–¶§Ãj¢–²ŠjjžÊ‰®º�°¡¶¡º®–®HH®Nn‰¡¢Jrzj¢¶ÿ±žƒj·¥²ž±ž±ž�zz—±¶z¶¹qj�ÉzµŠºº®²1²ÊŠ¢yµ†ÿÂŠ

Sunday, October 11, 2009

RE: Question-Shar Failure of Shallow Foundation

Mandeep,

I am guessing, that it has something to do with a 45 degree failure plane. Whilst the punching shear, may have more of a bearing area distribution, which tends to have a 1:2 distribution. The punch through should occur close to the face of the punch. The further away from the punch the more bending and tearing occurs, and the less have pure shear.

But just guessing, since don' know much about concrete. But know a little about designing punches for deep drawing and blanking. Which in terms of steel the punch tends to penetrate about 2/3^rd's of depth, then the crack propagates the last 1/3^rd and a 45 degree fracture plane results. So maybe for resisting punch through design is based on half depth, and 45 degree failure plane.

Regards

Conrad Harrison

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

mailto:sch.tectonic@bigpond.com

Adelaide

South Australia