Structural Engineering: 2007-12-02

Saturday, December 8, 2007

Alternate Braced Walls and SDC D

I've read section 2308 of the 2007 CBC several times not and still cannot make up my mind on whether or not alternate braced walls are permitted in SDC 'D'. I'll read in once and think 'no way' but then another reading has me thinking 'maybe' until another reading has me back to 'no way'.

If they ARE permitted I don't think it will be the same as under the 2001 code since table 2308.12.4 places requirements on total braced wall length. If they are not permitted, I can see garages as requiring engineered shearwalls regardless of how the rest of the house is designed.

Any thoughts will be appreciated.

Gary Grinstead, SE
Stockton, CA

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RE: Openings in concrete beams

See Section 17.8, Openings in Beams, ""Reinforced Concrete Fundamentals, 5th Ed", Ferguson, Breen, and Jirsa, Wiley, 1988. ISBN 0-471-80378-2.

Bill Scott

From: alfred mueller [mailto:alfred.mueller@hmb-ingenieure.de]
Sent: Saturday, December 08, 2007 12:01 AM
To: seaint@seaint.org
Subject: AW: Openings in concrete beams

Hi David,

as the other two colleagues said, there is no problem to design RC- beams with openings. I have designed some of these in recent projects. I know several books, where are some explanations about that, but they are all in german speech. I don’t know, if some of them are translated. But there are also some explanations in the german code and therefore also in the European code, I think. So you should get this in english speech.

If you want, maybe, I can scan some papers out of my books and send them to you.

Regards

Alfred Mueller, SE, IWE

hmb- engineers, Karlsruhe, Germany

University of applied sciences, Karlsruhe, Germany

Von: Gaines, David [mailto:David.Gaines@hdrinc.com]
Gesendet: Freitag, 7. Dezember 2007 20:57
An: seaint@seaint.org
Betreff: Openings in concrete beams

Has anyone seen this in practice or done concrete beam design with openings before?

We are working on a new underground concrete parking structure with limited height and overhead clearance restrictions. The footprint is large, like 600 feet in the short direction so we need ventilation. We have 32 foot long and 63 foot long beams and 32 foot long girders. The longer beams are governed by bending, not shear at mid-span. I have preliminary beams designed to just fit the height. The architect is asking us if we can put an elongated hole in the beams and girders for ducting and pipes. These of course would be at the mid-span and not exceeding 1/3 the depth. I would prefer to use a round hole but they are asking for elongated holes. I can't find anything in text books or literature for designing an opening in concrete beams.

Has anyone done this type of beam design method before? Has anyone seen concrete structures designed with openings in the beams? Does anyone have a book or reference I can look for to find examples or methodology?

Seems like it would be more efficient to increase the floor to floor height and run the ducting underneath. Any comments on this?

Any help or input would be appreciated. Thanks,

Dave Gaines

Dave Gaines, P.E.

Structural Project Engineer
HDR ONE COMPANY | Many Solutions
251 S. Lake Ave, Suite 1000
Pasadena, CA 91101
T: 626.584.4960
F: 626.584.1750
email: david.gaines@hdrinc.com

RE: Boring through GLBs

It's hard to believe a contractor would do that without asking, but it I have seen it before. www.apawood.org has a publication for holes in glu lam beams, pretty much the standard prescriptive limitations. I wonder if the manufacturer would write a letter, but if they would, seems that would be to your benefit.

Jeff

From: Donald Bruckman [mailto:bruckmandesign@verizon.net]
Sent: Saturday, December 08, 2007 9:05 AM
To: seaint@seaint.org
Subject: Boring through GLBs

I have a building I designed being constructed here in SoCal which has a clear-spanned GLB floor girder system about 35 feet long with 36" deep beams. A few weeks ago I got a call from the GC telling me that the electrician, for reasons known only to the electrician, drilled a single 1 ¼" diameter hole through the GLB to fish some conduit through to an elevator room. After quizzing the GC about where the holes were, I found that they were bored about 10 feet from the point of support and near the center of the depth of the beam.

I was a bit miffed that it happened, but figured a hole that small in the center 1/3 of the depth of the beam away from the area of max moment wasn't going to be a big deal.

Well, my engineer was extremely upset about it and threatened to make them replace the beam. He finally agreed to approve it but I could not get any impression out of him whether it really was a big deal structurally or if he was just putting on a show to teach the GC a well deserved lesson. Meanwhile, the building inspector gets into the act and is asking for a letter from the manufacturer approving the holes, an idea I found very odd.

My question: What's going on here? What do I not know, after all these years in the biz, about holes in GLBs? From a reduced section standpoint, away from the point of max moment and near the center of depth, such a small hole seems relatively unimportant to me. Am I missing something?

-DB

Boring through GLBs

I have a building I designed being constructed here in SoCal which has a clear-spanned GLB floor girder system about 35 feet long with 36” deep beams. A few weeks ago I got a call from the GC telling me that the electrician, for reasons known only to the electrician, drilled a single 1 ¼” diameter hole through the GLB to fish some conduit through to an elevator room. After quizzing the GC about where the holes were, I found that they were bored about 10 feet from the point of support and near the center of the depth of the beam.

I was a bit miffed that it happened, but figured a hole that small in the center 1/3 of the depth of the beam away from the area of max moment wasn’t going to be a big deal.

My question: What’s going on here? What do I not know, after all these years in the biz, about holes in GLBs? From a reduced section standpoint, away from the point of max moment and near the center of depth, such a small hole seems relatively unimportant to me. Am I missing something?

-DB

Re: Great ASCE7 spreadsheet / ComboBoxes

Bill,

Thanks for sharing your knowledge. I learned something new and determined that INDIRECT function could be a powerful tool in several engineering calculations.

Have a great holiday season.

Rajendran

----- Original Message ----
From: Bill Allen <t.w.allen@cox.net>
To: seaint@seaint.org
Sent: Friday, December 7, 2007 9:50:07 AM
Subject: RE: Great ASCE7 spreadsheet / ComboBoxes

Thanks for the info, Conrad.

My best example of using the indirect function is in selecting the type of
wood beam I want to design. This example is much better than apples and
trees that Microsoft uses. I often design wood beams of different
properties; sawn beams, Glu-Lam beams (GLB) and Parallel Strand Laminated
(PSL) beams.

I first set up a validation list to select the type of beam (Sawn, GLB or
PSL). Whichever I choose, the options for the different sizes change based
on my selection. In other words, if I want to design a sawn beam, I have a
list consisting of 2x4, 4x8 or 6x12. If I want to design a GLB, my list
consists of 3-1/8"x12", 5-1/8"x18" or 6-3/4"x24". If I want to design a PSL
beam, my list would change to 3-1/2"x11-1/4", 5-1/2"x14" or 7"x20". From
there, you could have simple lookup commands to fetch section properties
such as the beam width and beam depth (among other things).

This procedure (at least the way I do it) requires named ranges. To assist
in the visualization, I've included a sample. Note: there are no VBA scripts
in this example so don't worry about a virus.

Have fun!

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

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Re: Live and Dead Load Spreadsheet

Dennis:

I would like to receive a copy of the Live & Dead Load Spreadsheet you have created.

Thank you in advance and I, too, appreciate the depth of experience that is so freely shared by the list!

Merry Christmas and Happy New Year!

Sincerely,

Bill

WISH DENNIS <dennis.wish@verizon.net> wrote:

I posted an e-mail to the list with a Live and Dead Load Spreadsheet calculator. I don't know if it was received but it was 102Kb in size. I forgot to zip it and did not know if it made it to the list. First, if it had and you find it useful then here is just a quick note on the spreadsheet. The Tables page lists all the materials and the square foot weights I used in the spreadsheet. Nothing is protected and you may change the values as you wish. The spreadsheet was saved in Excel 97-2003 format, but writtin in Excel 2007. There was some issue regarding a minor error due to the length of some of the references. If you have not received the spreadsheet and would like one or have found any problems with it please e-mail me and I will be happy to send you the Office 2007 version that I originally wrote.

You may change any of the table settings - the name of the materials (i.e. if you use pine instead of fir) and the unit weights. There may be some tables that do not apply as this was stripped out of the new MultiLat version I am creating. I needed it for a small project and decided to separate it for those times when I may be using another program such as Enercalc or StruCalc and only need the live and dead load of the materials. The additional tables may reference the work I am doing for the 2006 IBC MultiLat version.

Also, I wanted to thank Bill Allen for his information on Indirect functions. I've treated my lookups slightly differently as you will see on the Live and Dead load spreadsheet. Bill taught me a new trick and I really appreciate it. FWIW, I use the Index and Match functions to do what I think is the same thing that Bill does with the Indirect function. I also use the same Data Validation features to create the embedded pull-down menu's rather than using the older ActiveX tools. This is a very nice feature that displays your pull-down menu arrow as you move the cursor over the cell. I think this is a new feature in the 2003 version of Excel that did not exist in the 97 Excel.

Thank you all for your much needed contributions to our profession (and I do not say this lightly as it is one thing to know what you can do but another to help others learn to use these powerful tools) and to create analysis tools that you are willing to share with your professional peers. This says a lot for those who are willing to help others with time saving tools. Please, though, let me add this warning. As hard as we try to make the tools we design as free of defect as possible, the ultimate decision as to the adequacy of the tool must be left to the user. Never start with the assumption that the tool we give away is accurate - a great deal of labor goes into creating the tools and your feedback will alert us of any problems we have missed. The ultimate decision making is your experience and professional abilities to determine when a solution is not within the realm of being accurate. Never simply trust what is give away or even that which is sold - errors do occur and for this reason these tools should never be used by anyone who does not have a solid engineering background especially in the area that these tools address.

With this said, may all of you have a joyous and safe holiday season. Again, than you Yo Ratanapeanchai for your contribution and Bill for what you have taught me.

Best regards,

Dennis

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

William E. Lehmer, P.E.
11060 Timberview Drive
Manassas, VA 20111
703-369-1045 home
571-224-4173 mobile
540-347-5001 work

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AW: Openings in concrete beams

Hi David,

If you want, maybe, I can scan some papers out of my books and send them to you.

Regards

Alfred Mueller, SE, IWE

hmb- engineers, Karlsruhe, Germany

University of applied sciences, Karlsruhe, Germany

Von: Gaines, David [mailto:David.Gaines@hdrinc.com]
Gesendet: Freitag, 7. Dezember 2007 20:57
An: seaint@seaint.org
Betreff: Openings in concrete beams

Has anyone seen this in practice or done concrete beam design with openings before?

Seems like it would be more efficient to increase the floor to floor height and run the ducting underneath. Any comments on this?

Any help or input would be appreciated. Thanks,

Dave Gaines

Dave Gaines, P.E.

Structural Project Engineer
HDR ONE COMPANY | Many Solutions
251 S. Lake Ave, Suite 1000
Pasadena, CA 91101
T: 626.584.4960
F: 626.584.1750
email: david.gaines@hdrinc.com

Friday, December 7, 2007

Re: Openings in concrete beams

Dave,

How deep are your beams for a 32' span? Standard beams for US parking structures are often much deeper than actually needed. Australia and Asia tend to use different beam shapes that provide much shallower beams!

At 05:57 AM 8/12/2007, you wrote:

Has anyone seen this in practice or done concrete beam design with openings before?

We are working on a new underground concrete parking structure with limited height and overhead clearance restrictions. The footprint is large, like 600 feet in the short direction so we need ventilation. We have 32 foot long and 63 foot long beams and 32 foot long girders. The longer beams are governed by bending, not shear at mid-span. I have preliminary beams designed to just fit the height. The architect is asking us if we can put an elongated hole in the beams and girders for ducting and pipes. These of course would be at the mid-span and not exceeding 1/3 the depth. I would prefer to use a round hole but they are asking for elongated holes. I can't find anything in text books or literature for designing an opening in concrete beams.

Has anyone done this type of beam design method before? Has anyone seen concrete structures designed with openings in the beams? Does anyone have a book or reference I can look for to find examples or methodology?

Seems like it would be more efficient to increase the floor to floor height and run the ducting underneath. Any comments on this?

Any help or input would be appreciated. Thanks,
Dave Gaines

Dave Gaines, P.E.

Structural Project Engineer
HDR ONE COMPANY | Many Solutions
<?xml:namespace prefix = st1 ns = "urn:schemas-microsoft-com:office:smarttags" /><?XML:NAMESPACE PREFIX = U1 />251 S. Lake Ave, Suite 1000
Pasadena, CA 91101
T: 626.584.4960
F: 626.584.1750
email: david.gaines@hdrinc.com <?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />

Regards Gil Brock
Prestressed Concrete Design Consultants Pty. Ltd. (ABN 84 003 163 586)
5 Cameron Street Beenleigh Qld 4207 Australia
Ph +61 7 3807 8022               Fax +61 7 3807 8422
email:            gil@raptsoftware.com
email:            sales@raptsoftware.com
email:            support@raptsoftware.com
webpage:         http://www.raptsoftware.com

Live and Dead Load Spreadsheet

I posted an e-mail to the list with a Live and Dead Load Spreadsheet calculator. I don't know if it was received but it was 102Kb in size. I forgot to zip it and did not know if it made it to the list. First, if it had and you find it useful then here is just a quick note on the spreadsheet. The Tables page lists all the materials and the square foot weights I used in the spreadsheet. Nothing is protected and you may change the values as you wish. The spreadsheet was saved in Excel 97-2003 format, but writtin in Excel 2007. There was some issue regarding a minor error due to the length of some of the references. If you have not received the spreadsheet and would like one or have found any problems with it please e-mail me and I will be happy to send you the Office 2007 version that I originally wrote.

You may change any of the table settings - the name of the materials (i.e. if you use pine instead of fir) and the unit weights. There may be some tables that do not apply as this was stripped out of the new MultiLat version I am creating. I needed it for a small project and decided to separate it for those times when I may be using another program such as Enercalc or StruCalc and only need the live and dead load of the materials. The additional tables may reference the work I am doing for the 2006 IBC MultiLat version.

Also, I wanted to thank Bill Allen for his information on Indirect functions. I've treated my lookups slightly differently as you will see on the Live and Dead load spreadsheet. Bill taught me a new trick and I really appreciate it. FWIW, I use the Index and Match functions to do what I think is the same thing that Bill does with the Indirect function. I also use the same Data Validation features to create the embedded pull-down menu's rather than using the older ActiveX tools. This is a very nice feature that displays your pull-down menu arrow as you move the cursor over the cell. I think this is a new feature in the 2003 version of Excel that did not exist in the 97 Excel.

Thank you all for your much needed contributions to our profession (and I do not say this lightly as it is one thing to know what you can do but another to help others learn to use these powerful tools) and to create analysis tools that you are willing to share with your professional peers. This says a lot for those who are willing to help others with time saving tools. Please, though, let me add this warning. As hard as we try to make the tools we design as free of defect as possible, the ultimate decision as to the adequacy of the tool must be left to the user. Never start with the assumption that the tool we give away is accurate - a great deal of labor goes into creating the tools and your feedback will alert us of any problems we have missed. The ultimate decision making is your experience and professional abilities to determine when a solution is not within the realm of being accurate. Never simply trust what is give away or even that which is sold - errors do occur and for this reason these tools should never be used by anyone who does not have a solid engineering background especially in the area that these tools address.

With this said, may all of you have a joyous and safe holiday season. Again, than you Yo Ratanapeanchai for your contribution and Bill for what you have taught me.

Best regards,

Dennis

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

Re: Perforated shear walls

Jeff Hedman wrote:
>
> Chuck,
>
> There was no strapping on the outside of the building, but it is
> possible that there could have been strapping on the inside. So your
> are saying that if the openings are treated like an opening in the
> diaphragm, then the height to width ratios no longer apply? Which all
> of the extra stuff to do calculate with perforated shear walls, and
> the reduction in shear capacity, is it ever really worth it to use them?
>
>
>
>
>
Take a look at Fig. 2305.3.5. You still need to consider ht./width
ratios. You need an analysis in either case--"rational" or the
"perforated shearwall" stuff in the Code. You still need hardware. Out
here in earthquake country I'm not comfortable with unreinforced
openings in the middle of my shearwalls--YMMV.
Chuck Utzman, PE

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

Re: sustainable companies

AK,

I just want to thank you for your mini-essay on sustainability and 'Mericanism. It's the funniest thing I've read in a long time. I keep it posted beside my desk to remind me what's *really* important in this life.

Oh, you were serious? Oh.

PBR to you too!

Ralph

In a message dated 11/12/07 12:11:07 PM, akester@cfl.rr.com writes:

Erik,

I am totally with Bill and his line of thinking. And to be honest, you sound sorta like you hate freedom. The freedom to build whatever the hell you want and flip the bird to the world is our American right. Its in the Constitution, which you probably can barely read since you sound like you were educated in the public school system.

You must realize you need a 4 car garage, where can you put your Hummer, Expedition, boat and jet ski. And what kind of hippy wants 3 people to crowd into a tiny 4000sf house with dinky 12 ft ceilings. How can you not derive supreme pleasure over designing these knowing their utilitarian function? And of course the next logical step in questioning this way of thinking would be to go work for Greenpeace and build houses of crap. There is no in-between or gray on this issue or any other issue, just like in all of real life.

Why don't you go shoot or save some deer, I am not sure which but they both make sense. I think as long as you eat the deer it is OK. Which is why I pick up every liberal tree hugging squirrel I run over.

Who cares if they are not energy efficient, require tons of building materials, could house a small 3rd world village, can be nearly impossible to properly structurally engineer because the more cut up a roof line the more architecturally pleasing it is, and above all, are completely over the top look at me and all of my insecurities and I am so trying to keep up with the joneses and drowning in debt to do so. Just cash your check and be happy you got a job in the greatest country ever (or GEEEETTTT OUUUUTTTT). If you stopped hitting the bong and put out the incense long enough, one day you may open up your own company and do whatever you want with whatever conscious you have. I mean, I don't believe in Jesus as my saviour but we engineer lots of churches. I think strip clubs are a waste of money but I would design them too. Liquor stores, gun shops, drug dealer's house, Al Gore's save the earth hippy house or a steel framed behemoth to support Rush's 400psf LL requirements, whatever pays my bills. Conscious and caring are for pansies, bunch of liberal fuzzy warm feeling crap.

Now drink a case of PBR and maybe you will wake up on the RIGHT side of bed and realize how good you got it in 'Merica.

Andrew

erik gibbs wrote:
> I do not like engineering large, very large custom homes with a lot of
> wastefull architecture.
Then quit, and go to work for Greenpeace or some outfit like that. Maybe
you can get involved in making homes out of Wildebeest dung, or some
other such thing that is more in line with your religious convictions.

(BTW, to me, "sustainable buildings" are the ones still standing after
an earthquake or a hurricane).

--------------------------------------------------------------------------
2 Message:0002 2
--------------------------------------------------------------------------
From: Bill Polhemus <bill@polhemus.cc>
To: seaint@seaint.org
Subject: Re: Sustainable companies

Christopher Wright wrote:
>
> On Nov 9, 2007, at 9:27 PM, erik gibbs wrote:
>
>> What are your thoughts on sustainable structural engineering/
>> building and or what companies implement this design method?
> We live in a wasteful way because we've always had more than enough of
> everything.
We live in a "wasteful way" because that's the nature of human beings
whenever possible.

You want to see creatures living in a "wasteful way?" See what happens
when deer are allowed to grow in population with no natural predators
around.

Andrew Kester, PE
Principal/Project Manager
ADK Structural Engineering, PLLC
1510 E. Colonial Drive, Suite 301
M 407-921-1617
F 321-249-0349

**************************************
Check out AOL's list of 2007's hottest products.
(http://money.aol.com/special/hot-products-2007?NCID=aoltop00030000000001)

RE: Perforated shear walls

> height to width ratios no longer apply

The height to width ratios would still apply, it just that the height would be taken as the height between the straps rather than the full height.

>is it ever really worth it to use them

We never use them, providing strapping, in my mind, is a must better system. And at the end of the night I can sleep!

Jason

-----Original Message-----
From: Jeff Hedman [mailto:jeff_h@lrpope.com]
Sent: Friday, December 07, 2007 12:19 PM
To: seaint@seaint.org
Subject: RE: Perforated shear walls

Chuck,

There was no strapping on the outside of the building, but it is possible that there could have been strapping on the inside. So your are saying that if the openings are treated like an opening in the diaphragm, then the height to width ratios no longer apply? Which all of the extra stuff to do calculate with perforated shear walls, and the reduction in shear capacity, is it ever really worth it to use them?

Jeff Hedman , E.I.T.

L.R. Pope Engineers & Surveyors, Inc.

1240 East 100 South Suite # 15B

St. George, Utah 84790

Office: 435-628-1676

Fax: 435-628-1788

RE: Perforated shear walls

Being built does not mean that it went through the city permit process this year. Utah accepted the IBC 2006 in Jan. of 2007. If the plan went through the city last December it could have been designed and accepted under the 2003 code. Now as in my other post, 2003 code did not specifically tell you what h/w to use. So they may have used that design process. I am guessing that someone screwed up and it was never caught, or they used the 2*w/h reduction value (reducing the allowable capacities) which was added to the 2003 IBC.

Example of the 2*w/h per IBC 2006 Table 2305.3.4 footnote a.

Say you have a shear wall loaded with 210plf, try 3/8” sheathing with 8d at 6-12 GF = 220plf . Height = 10ft, width = 4ft. h/t = 2.5. This does not meet the 2:1 ratio. However per the footnote a of Table 2305.3.4 you and reduce the capacity by 2*w/h, 2*4/10 = 0.8, therefore the 0.8*220 = 176plf N.G.. Use 7/16 sheathing with 8d at 4-12 GF = 0.8*350 = 280plf OK.

Not magic but it does allow you use smaller widths of walls.

Jason

-----Original Message-----
From: Jeff Hedman [mailto:jeff_h@lrpope.com]
Sent: Friday, December 07, 2007 11:43 AM
To: seaint@seaint.org
Subject: RE: Perforated shear walls

Jason,

The building was built here in St. George this year (which would be IBC 2006). In fact the building was just completed in the last month or two. I am just wondering if there is a wood shear wall method that was used for this situation that I am unaware of (or magic). I have had to design buildings like this before and have had to get the architect to change the wall lengths, use strong walls, or in one case we changed to masonry.

Jeff Hedman , E.I.T.

L.R. Pope Engineers & Surveyors, Inc.

1240 East 100 South Suite # 15B

St. George, Utah 84790

Office: 435-628-1676

Fax: 435-628-1788

RE: Openings in concrete beams

David:

I'm glad to hear from you.

I've done a lot of deep steel beams with large opening in them.

For those It's simple static.

For RC beams, depending on your beam depth and size of the opening, in addition to calculation of the section properties you would also want to detail it with add'l diagonal rebars fully developing well back into the solid section of the beam.

Regards
Casey (Khashayar) Hemmatyar, SE

From: Gaines, David [mailto: David.Gaines@hdrinc.com]
Sent: Friday, December 07, 2007 11:57 AM
To: seaint@seaint.org
Subject: Openings in concrete beams

Has anyone seen this in practice or done concrete beam design with openings before?

Seems like it would be more efficient to increase the floor to floor height and run the ducting underneath. Any comments on this?

Any help or input would be appreciated. Thanks,

Dave Gaines

Dave Gaines, P.E.

Structural Project Engineer
HDR ONE COMPANY | Many Solutions
251 S. Lake Ave, Suite 1000
Pasadena, CA 91101
T: 626.584.4960
F: 626.584.1750
email: david.gaines@hdrinc.com

RE: Openings in concrete beams

The portions of the beam above and below the opening are designed for their portion of the flexural and shear stresses, at the point of the span where the opening occurs, based on each section’s relative stiffness. The portion of the beam at each side of the opening is then designed for Vierendeel action. Lastly, you must analysis the deflection of the beam based on the variable inertia of the beam in combination with the Vierendeel distortion.

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

Senior Project Manager

Structural Department

Associate

200 Route 9

Manalapan, NJ 07726

732-577-9000 (Ext. 1285)

908-309-8657 (Cell)

732-298-9441 (Fax)

mstuart@CMXEngineering.com

-----Original Message-----
From: Gaines, David [mailto:David.Gaines@hdrinc.com]
Sent: Friday, December 07, 2007 2:57 PM
To: seaint@seaint.org
Subject: Openings in concrete beams

Has anyone seen this in practice or done concrete beam design with openings before?

Seems like it would be more efficient to increase the floor to floor height and run the ducting underneath. Any comments on this?

Any help or input would be appreciated. Thanks,

Dave Gaines

Dave Gaines, P.E.

Structural Project Engineer
HDR ONE COMPANY | Many Solutions
251 S. Lake Ave, Suite 1000
Pasadena, CA 91101
T: 626.584.4960
F: 626.584.1750
email: david.gaines@hdrinc.com

Openings in concrete beams

Has anyone seen this in practice or done concrete beam design with openings before?

Seems like it would be more efficient to increase the floor to floor height and run the ducting underneath. Any comments on this?

Any help or input would be appreciated. Thanks,

Dave Gaines

Dave Gaines, P.E.

Structural Project Engineer
HDR ONE COMPANY | Many Solutions
251 S. Lake Ave, Suite 1000
Pasadena, CA 91101
T: 626.584.4960
F: 626.584.1750
email: david.gaines@hdrinc.com

RE: Perforated shear walls

Chuck,

Jeff Hedman , E.I.T.

L.R. Pope Engineers & Surveyors, Inc.

1240 East 100 South Suite # 15B

St. George, Utah 84790

Office: 435-628-1676

Fax: 435-628-1788

RE: Perforated shear walls

Jason,

Jeff Hedman , E.I.T.

L.R. Pope Engineers & Surveyors, Inc.

1240 East 100 South Suite # 15B

St. George, Utah 84790

Office: 435-628-1676

Fax: 435-628-1788

Re: Perforated shear walls

Jeff Hedman wrote:
>
> Jason,
>
> If the height to width ratios still apply, any idea how this building
> got through plan check with shear walls that don't meet the ratios?
>
>
>
> Jeff Hedman /*/, E.I.T./*/
>
> L.R. Pope Engineers & Surveyors, Inc.
>
> 1240 East 100 South Suite # 15B
>
> St. George, Utah 84790
>
> Office: 435-628-1676
>
> Fax: 435-628-1788
>
>
>
>
> No virus found in this outgoing message.
> Checked by AVG Free Edition.
> Version: 7.5.503 / Virus Database: 269.16.17/1176 - Release Date:
> 12/6/2007 11:15 PM
>
Are you sure that the headers &/or sills of the openings aren't
strapped horizontally?
Chuck Utzman,PE

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

RE: Perforated shear walls

Under the 2000 and the 2003 code the figure I mentioned did not include the perforated shear walls. There were reductions that you needed to take from table 2305.3.7.2 which adjusted your capacity depending on percent of full-height sheathing.

For the 2003 IBC section 2305.3.7.2.2 parts 2 & 3, which talk about the height of your piers it does not specifically say that you need to meet the 2:1 or 3.5:1 ratio.

For the 2006 IBC this same section (now named as section 2305.3.8.2.2 parts 2 & 3) was changed and does now specifically include the 2:1 or 3.5:1 ratio.

Whether the intent was to be included in the 03 and 00 codes I am not sure, but I know of designs and engineers that said the percent full height reduction took into consideration the height-to-width ratio. So if the building was built under the 03 or 00, it may have met the code. I don’t know if I agree with the reasoning but it made sense, at the time.

Jason

-----Original Message-----
From: Jeff Hedman [mailto:jeff_h@lrpope.com]
Sent: Friday, December 07, 2007 10:28 AM
To: seaint@seaint.org
Subject: Re: Perforated shear walls

Jason,

If the height to width ratios still apply, any idea how this building got through plan check with shear walls that don’t meet the ratios?

Jeff Hedman , E.I.T.

L.R. Pope Engineers & Surveyors, Inc.

1240 East 100 South Suite # 15B

St. George, Utah 84790

Office: 435-628-1676

Fax: 435-628-1788

RE: Perforated shear walls

For the 2003 IBC section 2305.3.7.2.2 parts 2 & 3, which talk about the height of your piers it does not specifically say that you need to meet the 2:1 or 3.5:1 ratio.

For the 2006 IBC this same section (now named as section 2305.3.8.2.2 parts 2 & 3) was changed and does now specifically include the 2:1 or 3.5:1 ratio.

Jason

-----Original Message-----
From: Jeff Hedman [mailto:jeff_h@lrpope.com]
Sent: Friday, December 07, 2007 10:28 AM
To: seaint@seaint.org
Subject: Re: Perforated shear walls

Jason,

If the height to width ratios still apply, any idea how this building got through plan check with shear walls that don’t meet the ratios?

Jeff Hedman , E.I.T.

L.R. Pope Engineers & Surveyors, Inc.

1240 East 100 South Suite # 15B

St. George, Utah 84790

Office: 435-628-1676

Fax: 435-628-1788

RE: Great ASCE7 spreadsheet / ComboBoxes

You're welcome.

I'm glad I can make a contribution.

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

> -----Original Message-----
> From: Doug Mayer [mailto:doug.mayer@taylorteter.com]
> Sent: Friday, December 07, 2007 9:34 AM
> To: seaint@seaint.org
> Subject: RE: Great ASCE7 spreadsheet / ComboBoxes
>
> Very nice Bill. Thanks for sharing that as I had not yet seen a good
> example of the "Indirect" function. I will definitely be using that
> from now on.
>
> Doug Mayer, SE
> Structural Engineer
>
> -----Original Message-----
> From: Bill Allen [mailto:t.w.allen@cox.net]
> Sent: Friday, December 07, 2007 7:50 AM
> To: seaint@seaint.org
> Subject: RE: Great ASCE7 spreadsheet / ComboBoxes
>
> Thanks for the info, Conrad.
>
> My best example of using the indirect function is in selecting the type
> of wood beam I want to design. This example is much better than apples
> and trees that Microsoft uses. I often design wood beams of different
> properties; sawn beams, Glu-Lam beams (GLB) and Parallel Strand
> Laminated
> (PSL) beams.
>
> I first set up a validation list to select the type of beam (Sawn, GLB
> or PSL). Whichever I choose, the options for the different sizes change
> based on my selection. In other words, if I want to design a sawn beam,
> I have a list consisting of 2x4, 4x8 or 6x12. If I want to design a GLB,
> my list consists of 3-1/8"x12", 5-1/8"x18" or 6-3/4"x24". If I want to
> design a PSL beam, my list would change to 3-1/2"x11-1/4", 5-1/2"x14" or
> 7"x20". From there, you could have simple lookup commands to fetch
> section properties such as the beam width and beam depth (among other
> things).
>
> This procedure (at least the way I do it) requires named ranges. To
> assist in the visualization, I've included a sample. Note: there are no
> VBA scripts in this example so don't worry about a virus.
>
> Have fun!
>
> T. William (Bill) Allen, S.E.
> ALLEN DESIGNS
> Consulting Structural Engineers
>
> Visit our new website at www.taylorteter.com
>
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