Structural Engineering: 2009-01-11

Saturday, January 17, 2009

Re: Lateral Stability of a Box Beam ?

If the 2 beams are identical with identical loading, there is no benefit to
simple ties. Unless there is some shear resistance mechanism between the
brace points, the unbraced length for lateral buckling is not reduced and
the ladder simply behaves like 2 tied beams (e.g. Iy1 + Iy2) and they just
displace in unison.

Regards
Paul
--
Paul Ransom, P.Eng.
ph 905 639-9628
fax 905 639-3866
ad026@hwcn.org

> From: "Conrad Harrison" <sch.tectonic@bigpond.com>

> Have you considered providing short bridging members between the two beams:
> to create a kind of ladder, or otherwise similar to battened column. The
> displacement of one beam then becomes tied to the displacement of the other
> and the effective length for lateral buckling is reduced. Could still use
> plywood top and bottom for the bridging/bracing it just doesn't have to be
> continuous box section: unless have an aesthetic reason.

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Friday, January 16, 2009

Wind Provision Seminar

Hi Don,

I was trying to register on line but the cost is shown as $175 + $125 for a total of $300. The flier shows it as $125. Which is correct?

Thanks,

Jeff Coronado, S.E.
Jeff Coronado Structural Engineering Consultants
553 St Malo Street
West Covina, CA 91790
626-472-0070
626-472-0071 Fax
jeff@jcseconsultants.com
Website: www.jcseconsultants.com

re: multiple subjects

Wind on soffits: Agree with Conrad, we always have used the wall pressure of soffits or U/S of overhangs. If you take overhang pressures (which include both surfaces) and compare them to a roof edge pressure + wall pressure, they will be very close. Think about every canopy in front of every retail box, this condition exists. My thinking has always been positive wind pressure hits the wall, goes up, hits the soffit with equal or lesser pressure. Just some common sense, no wind tunnel testing or Bernoulli-type thinking.

Tanks in-ground in Gulf region: Persian Gulf or Gulf of Mexico? All the Gulf Coast states in the US, near the coast, have very high water tables. You must design for buoyancy, the tank can pop out of the ground in the summer wet months. Seen it happen with swimming pools that are emptied when the table is up, still blows my mind! Get a geotech report so you know if you have clay and where your seasonal high water table, as well as your 100yr flood water table is located. In Florida those who design pump stations have to consider this, which just means thicker tank walls which helps you structurally.

Wood box beam- Bill, how much is just a little load? For big fun on a Friday afternoon, I calc’d on Enercalc a 27ft span with low grade S Pine, with a base Fbt and Fbc= 900psi, (2) 2x14 work but not by much complete unbraced (bending stress ratio=0.902). But fully bracing these only reduces it down to 0.827. That assumes self weight and 50plf dead load.

However, regarding sheathing as part of a box beam, will this be built on the ground and then erected as a box, or the plywood will be added after the beams are up. The first really acts as a composite beam with the plywood in compression and tension, and the 2x beams are webs in shear (technically you need to design the fasteners for shear in shear flow, I am sure 12d at 6” oc would be fine).

The second I think would be more like using the sheathing the same as a floor or roof diaphragm, with the beams already loaded there would be little composite action and shear flow through the nails. I think the sheathing in this instance would be more than adequate as a bracing member if it is 12” wide and very lightly loaded. Sounds like if you use reasonable sizes you will be fine either way due to the light load. You could analyze the crap out of this and you will likely find you are being very conservative either way and have a lot more capacity then you think…

HTH,

Andrew Kester, PE

Orlando, FL

Re: CBO Contact

Casey,

Thank you so much for the info.

Antonio S. Luisoni

A Good Credit Score is 700 or Above. See yours in just 2 easy steps!

RE: Wind

Gary & Conrad,

Thanks for the input.

Doug Mayer, SE

From: Ehrlich, Gary [mailto:gehrlich@nahb.com]
Sent: Friday, January 16, 2009 5:57 AM
To: seaint@seaint.org
Subject: RE: Wind

Doug & Conrad,

I did not see anything in a quick scan of ASCE 7-05 (provisions or commentary). However, the Wind Load Subcommittee is working on new language that would implement what Conrad said, i.e. use the same C&C wind pressure as for the adjacent wall surface. There is a paper from Peter Vickery in the May 2008 ASCE Journal of Structural Engineering that provides the necessary supporting data.

Gary

Gary J. Ehrlich, PE
Program Manager, Structural Codes & Standards
National Association of Home Builders (NAHB)
1201 15th Street, NW, Washington, DC 20005
ph: 202-266-8545 or 800-368-5242 x8545
fax: 202-266-8369
gehrlich@nahb.com

Attend the 2009 International Builders' Show
January 20-23, 2009, Las Vegas, NV
www.BuildersShow.com

From: Conrad Harrison [mailto:sch.tectonic@bigpond.com]
Sent: Thursday, January 15, 2009 7:11 PM
To: seaint@seaint.org
Subject: RE: Wind

Doug,

Typically the wind on the underside of an eaves overhang equals that on the adjacent wall surface. For example from ASCE7-05 Fig6-6 Cp=+0.8 for the windward wall, so soffit would experience Cp=+0.8 (upwards), whilst sidewalls experience Cp=-0.7 (downwards), and leeward Cp=-0.5(max. mag.) (downwards). Adopt similar approach for C&C pressures.

Not sure where rule is in ASCE7 but it is the approach used to AS1170.2, and I recollect something in commentary to ASCE7-05.

Regards

Conrad Harrison

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

mailto:sch.tectonic@bigpond.com

Adelaide

South Australia

RE: Wind

Doug & Conrad,

Gary

Attend the 2009 International Builders' Show
January 20-23, 2009, Las Vegas, NV
www.BuildersShow.com

From: Conrad Harrison [mailto:sch.tectonic@bigpond.com]
Sent: Thursday, January 15, 2009 7:11 PM
To: seaint@seaint.org
Subject: RE: Wind

Doug,

Not sure where rule is in ASCE7 but it is the approach used to AS1170.2, and I recollect something in commentary to ASCE7-05.

Regards

Conrad Harrison

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

mailto:sch.tectonic@bigpond.com

Adelaide

South Australia

Re: Lateral Stability of a Box Beam ?

This may not be much help, but I reviewed four fire halls in Fort Erie
(across the river from Buffalo) for structural integrity. One of them
had what appeared at first glance to be poured concrete beams until I
noticed a hole in one. They turned out to be plywood box beams,
trapezoidal in shape, wider at the top. I believe I asked the list at
the time and no one was able to give me a specific answer but someone
seemed to recall that these were being promoted at the time (1950s?) by
the plywood industry? Perhaps there is someone out there who can help. I
would like to learn more about them also.
Gary

Bill Allen wrote:
>
> I have a situation requiring two beams, approximately 12" apart
> spanning about 27 feet. They aren't supporting much more than their
> own weight, but I'm concerned that if I just use the span as the
> unbraced length, the beams are going to be very large.
>
> I would like to put plywood top and bottom to increase the effective
> lateral torsional strength. Is there a good reference in determining
> the capacity of such an assembly in wood?
>
> Thank you,
>
> T. William (Bill) Allen, S.E.
>
> ALLEN DESIGNS <http://www.AllenDesigns.com>
>
> Consulting Structural Engineers
> V (949) 248-8588 • F(949) 209-2509
>

Re: Catenary

I'm lazy too. That's why I went into engineering. Ha! Ironic?
Gary

Thor Tandy wrote:
> I'm lazy anyway, and I like "plug & play" :^)
>
> Thor
>
> -----Original Message-----
> From: Conrad Harrison [mailto:sch.tectonic@bigpond.com]
> Sent: Wednesday, January 14, 2009 4:21 PM
> To: seaint@seaint.org
> Subject: RE: Catenary
>
> Thor,
>
> Is the catenary sloping? Or are the supports at different levels?
>
> Norris and Wilbur elementary structural analysis covers cables, with general
> theorem for supports at different levels.
>
> Regards
> Conrad Harrison
> B.Tech (mfg & mech), MIIE, gradTIEAust
> mailto:sch.tectonic@bigpond.com
> Adelaide
> South Australia
>
>
>
> ******* ****** ******* ******** ******* ******* ******* ***
> * 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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Thursday, January 15, 2009

Underground Water Tank in Gulf

List,

Any watch-its for the design of large underground potable water tank in gulf region?

Tank size:

length= 50m

width= 100m

height= 5m

TIA,

Mondo

Bridge Seismic Analysis

I'm currently working on a bridge design in Puerto Rico, and I am wondering
about the validity of the procedure for seismic design used for some local
engineers.

As an example, consider a two-span bridge with a central pier. The deck
composed of AASHTO-Girders. At the ends there are counterfort abutments.
There are reinforced elastomeric bearing pads at each support. The bridge
superstructure is intended to be designed as continuous beam, and thus
having positive moments at central pier. There are 2" gaps between the
superstructure and the abutments. There are reinforced concrete shear blocks
in the transverse direction, having 1/2" gaps with the girders.

Structural computer models are:
MODEL 1: A continuous beam and the central pier with springs at
superstructure supports representing the neoprene pads.
MODEL 2: A continuous beam and the central pier with springs at
superstructure supports with 1-spring representing one abutment moving
toward backfill and the remaining springs representing elastomeric pads.

The procedure for seismic modeling and design consider the following steps:
1. Perform the analysis for the gravitary loads.
2. Design the elastomeric pads.
3. Find the equivalent springs to represent the horizontal and vertical
stiffness of the elastomers. The bridge is assumed restrained both
longitudinal and transversely by the elastomers only. No anchor bolts or
another anchoring device is assumed to be used at supports.
4. Perform a multimodal elastic dynamic analysis (MMEDA) for 'Model 1',
considering the elastomers stiffness, both in the horizontal and vertical
direction.
5. Since the horizontal displacements in 'Model 1' are greater than the
bridge gaps, usually in a proportion of 3 to 5, a second MMEDA is made for
'Model 2'. In this new model, the gap at one of the abutments is assumed
closed, and one of the end springs representing the stiffness of the
abutment with the soil passive resistance contribution.
6. Design of the bridge components using the more critical forces from both
analyses.

My objections to the described procedure are:
1. The elastomers were designed only for gravitary loads, but used for
seismic loads and not meeting the specifications for seismic isolated
bridges.
2. The MMEDA assumes systems having free oscillation. Closing gaps produces
collisions disturbing that oscillation and therefore the MMEDA becomes
invalid.
3. The MMEDA assumes the combination of the different vibration modes of the
system. The maximum modal displacements are not simultaneous and there are
some combination procedures (CQC, SRSS and others), to find the total
expected displacements with the contribution of the most significant modes.
Some time interval of free oscillation and certain number of cycles are
required by the system to reach the maximum displacement having a close
correlation with the analytical modal combination techniques. With the
procedure above, it is possible to have one of the end gaps closed even
without the first cycle completion for some modes.
4. Usually the abutments have skew angles respect the bridges longitudinal
axis. Therefore, the dynamic equations of movement are coupled. The gaps
closing and opening in longitudinal and transverse direction behaves
randomly, introducing more non-linearity to the system.
5. A MMEDA is only intended to be used in linear elastic systems. A
horizontal force vs. displacement plot is bilinear. The unloading trajectory
is also bilinear. Is by definition a non-linear system. For non-linear
systems step-by-step analysis or other analyses methods could be used.

My questions:
1. Do you agree with my objections for the described procedure?
2. It is possible to analyze a bridge in the example without using a
non-linear analysis tool?
3. Any comments?

Regards,
Jorge Jimenez, PE

RE: Tax Day Today

It appears to just slightly slow down the process!
Regards,
Bill Cain, SE

Date: Thu, 15 Jan 2009 14:07:33 -0800
From: markajohn@yahoo.com
Subject: Tax Day Today
To: seaint@seaint.org

Just a reminder. This is the day for Quarterly tax payments. If you don't pay your taxes, you may have a rough time if you want to be US Treasury Secretary.

MJ

Windows Live™: Keep your life in sync. See how it works.

RE: Lateral Stability of a Box Beam ?

Bill,

Have you considered providing short bridging members between the two beams: to create a kind of ladder, or otherwise similar to battened column. The displacement of one beam then becomes tied to the displacement of the other and the effective length for lateral buckling is reduced. Could still use plywood top and bottom for the bridging/bracing it just doesn’t have to be continuous box section: unless have an aesthetic reason.

Regards

Conrad Harrison

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

mailto:sch.tectonic@bigpond.com

Adelaide

South Australia

RE: Wind

Doug,

Not sure where rule is in ASCE7 but it is the approach used to AS1170.2, and I recollect something in commentary to ASCE7-05.

Regards

Conrad Harrison

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

mailto:sch.tectonic@bigpond.com

Adelaide

South Australia

Re: Wind - message show up

yup

--- On Thu, 1/15/09, Doug Mayer <doug.mayer@taylorteter.com> wrote:

From: Doug Mayer <doug.mayer@taylorteter.com>
Subject: Wind
To: seaint@seaint.org
Date: Thursday, January 15, 2009, 2:43 PM

Did my messages go through? No responses so far and I could really use the input.

Another question I have is how you are supposed to apply wind loads to exterior soffit framing? There doesn't seem to be any guidance in the code for something like this.

Doug Mayer, SE

Wind

Did my messages go through? No responses so far and I could really use the input.

Another question I have is how you are supposed to apply wind loads to exterior soffit framing? There doesn’t seem to be any guidance in the code for something like this.

Doug Mayer, SE

Tax Day Today

Just a reminder. This is the day for Quarterly tax payments. If you don't pay your taxes, you may have a rough time if you want to be US Treasury Secretary.

MJ

Re: Catenary

My office mates dispute my insistence that I'm lazy, so we've agreed to
call it "efficient" instead :-)

Jordan

Thor Tandy wrote:
> Hi Conrad.
>
> Supports are at different levels. It's actually on a 30deg slope, which is
> why I considered it significant enough to check. Had it been less than
> 10deg I probably wouldn't have bothered.
>
> Thanks to all the responses, I now have several references that will guide
> me through it all. I was going to do it from basics but I figured the work
> was already done. I'm lazy anyway, and I like "plug & play" :^)
>
> Thor
>
>

RE: Lateral Stability of a Box Beam ?

Does you architect hate square sections?

If not, CL=1.0 for square or nearly square sections --> No need to make a box beam.

Suresh Acharya, S.E.

From: Bill Allen [mailto:t.w.allen@cox.net]
Sent: Thursday, January 15, 2009 10:51 AM
To: seaint@seaint.org
Subject: Lateral Stability of a Box Beam ?

I have a situation requiring two beams, approximately 12" apart spanning about 27 feet. They aren't supporting much more than their own weight, but I'm concerned that if I just use the span as the unbraced length, the beams are going to be very large.

I would like to put plywood top and bottom to increase the effective lateral torsional strength. Is there a good reference in determining the capacity of such an assembly in wood?

Thank you,

T. William (Bill) Allen, S.E.

ALLEN DESIGNS

Consulting Structural Engineers
V (949) 248-8588 • F(949) 209-2509

RE: Lateral Stability of a Box Beam ?

That sounds like a typical plywood box beam. I'm checking AITC and the old UBC - I recall these were covered therein. I used to design a lot of these but that was back when I could remember. I'll keep looking.

Bob Garner, S.E.

From: Bill Allen [mailto:t.w.allen@cox.net]
Sent: Thursday, January 15, 2009 10:51 AM
To: seaint@seaint.org
Subject: Lateral Stability of a Box Beam ?

I would like to put plywood top and bottom to increase the effective lateral torsional strength. Is there a good reference in determining the capacity of such an assembly in wood?

Thank you,

T. William (Bill) Allen, S.E.

ALLEN DESIGNS

Consulting Structural Engineers
V (949) 248-8588 • F(949) 209-2509

RE: Lateral Stability of a Box Beam ?

Check out the APA website. They have some literature on plywood-lumber box beams that probably covers the subject.

Eric R. Ober, PE, SE

Associate

Holbert Apple Associates

3423 Olney-Laytonsville Rd., Ste. 6

Olney, Maryland 20832

(301)570-1460 (Phone)

(301)570-1462 (Fax)

-----Original Message-----
From: Bill Allen [mailto:t.w.allen@cox.net]
Sent: Thursday, January 15, 2009 1:51 PM
To: seaint@seaint.org
Subject: Lateral Stability of a Box Beam ?

I would like to put plywood top and bottom to increase the effective lateral torsional strength. Is there a good reference in determining the capacity of such an assembly in wood?

Thank you,

T. William (Bill) Allen, S.E.

ALLEN DESIGNS

Consulting Structural Engineers
V (949) 248-8588 • F(949) 209-2509

Lateral Stability of a Box Beam ?

I would like to put plywood top and bottom to increase the effective lateral torsional strength. Is there a good reference in determining the capacity of such an assembly in wood?

Thank you,

T. William (Bill) Allen, S.E.

ALLEN DESIGNS

Consulting Structural Engineers
V (949) 248-8588 • F(949) 209-2509

RE: Catenary

Hi Conrad.

Supports are at different levels. It's actually on a 30deg slope, which is
why I considered it significant enough to check. Had it been less than
10deg I probably wouldn't have bothered.

Thanks to all the responses, I now have several references that will guide
me through it all. I was going to do it from basics but I figured the work
was already done. I'm lazy anyway, and I like "plug & play" :^)

Thor

-----Original Message-----
From: Conrad Harrison [mailto:sch.tectonic@bigpond.com]
Sent: Wednesday, January 14, 2009 4:21 PM
To: seaint@seaint.org
Subject: RE: Catenary

Thor,

Is the catenary sloping? Or are the supports at different levels?

Norris and Wilbur elementary structural analysis covers cables, with general
theorem for supports at different levels.

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

RE: CBO Contact

Antonio:

Jay Elbettar, P.E., C.B.O

http://www.calbo.org/build_dept/default.aspx

Regards
Casey (Khashayar) Hemmatyar, SE
CA

Private email <khemmatyar_AT_hotmail.com>

________________________________________________

From: ASLCSE@aol.com [mailto:ASLCSE@aol.com]
Sent: Wednesday, January 14, 2009 5:03 PM
To: seaint@seaint.org
Subject: CBO Contact

Hello Engineers,

Is there a President of this organization? (Certified Building Offical)

Thanks

Antonio S. Luisoni

Consuting S.E.

Granada Hills, cA

SEAINT Server Test

Test

Wednesday, January 14, 2009

Re: curved beams

I remember a client/Architect that wanted me to hold up a structure so I designed him some sky hooks......

as long as the aircraft has fuel he is a happy camper.

Joe Venuti
Johnson & Nielsen Associates
Palm Springs, CA

In a message dated 1/14/2009 4:39:41 P.M. Pacific Standard Time, rgarner@moffattnichol.com writes:

First the tatoo artist couldn't figure out what the architect had drawn for his tatoo. It made absolutely no sense. When she figured it out, she realized it was not possible to do it in line work. So after figuring out what the Archie wanted, she completely redrew it for practicality, then went to work. But the Architect was afraid to let just anyone know he had a tat, so he had her stop it short just above his short-sleeve line. So you have this fantastic convoluted shape that just seems to stop with loose ends just above his sleeve line - imagine a skyscraper elevation cut off at about mid-level of the first floor with the columns dangling in space. That's his tattoo.

From: David Topete [mailto:d.topete73@gmail.com]
Sent: Wednesday, January 14, 2009 2:01 PM
To: seaint@seaint.org
Subject: Re: curved beams

was it the guggenheim they got on their forearm?

On Wed, Jan 14, 2009 at 1:50 PM, Garner, Robert <rgarner@moffattnichol.com> wrote:

Did anyone watch L.A. Ink where Kat tatoos an Architect?

From: Jimenez, Jorge A. [mailto:jajimenez@csagroup.com]
Sent: Wednesday, January 14, 2009 1:14 PM

To: seaint@seaint.org
Subject: RE: curved beams

We can ask to Stephen Hawking for an antimatter universe with other gravitational laws ideal for some architects, or help them to realize the limitations of our one.

Jorge Jimenez, PE

From: Harold Sprague [mailto:spraguehope@hotmail.com]
Sent: Wednesday, January 14, 2009 4:57 PM
To: seaint@seaint.org
Subject: RE: curved beams

There is another relatively painless method contained in Design of Welded Structures by Blodgett.

Regards, Harold Sprague

Date: Wed, 14 Jan 2009 11:37:38 -0800
From: prajendran@ymail.com
Subject: RE: curved beams
To: seaint@seaint.org

The only reference that quickly comes to my mind is AISC's "Torsion Analysis of Steel Members".

Rajendran

--- On Wed, 1/14/09, Gautam Manandhar <Gautam_Manandhar@ci.richmond.ca.us> wrote:

From: Gautam Manandhar <Gautam_Manandhar@ci.richmond.ca.us>
Subject: RE: curved beams
To: seaint@seaint.org
Date: Wednesday, January 14, 2009, 12:35 AM

List members:

I have a curved beam (horizontal). The center line of the beam layout is horizontally offset from the supporting post by about 10+ % of the span. The arch wants a channel section and will not allow a tube section. Can anyone suggest a quick method to check for flexure and torsion. DL is 480plf , LL = 800 plf. The project in under construction and the detail is due first thing to-morrow morning.

Gautam

.

Windows Live™ Hotmail®: Chat. Store. Share. Do more with mail. See how it works.

--
David Topete, SE

A Good Credit Score is 700 or Above. See yours in just 2 easy steps!

Re: curved beams

nice... i gotta find this online... and, no i don't believe all architects are total maroons... :-)

On Wed, Jan 14, 2009 at 4:35 PM, Garner, Robert <rgarner@moffattnichol.com> wrote:

First the tatoo artist couldn't figure out what the architect had drawn for his tatoo. It made absolutely no sense. When she figured it out, she realized it was not possible to do it in line work. So after figuring out what the Archie wanted, she completely redrew it for practicality, then went to work. But the Architect was afraid to let just anyone know he had a tat, so he had her stop it short just above his short-sleeve line. So you have this fantastic convoluted shape that just seems to stop with loose ends just above his sleeve line - imagine a skyscraper elevation cut off at about mid-level of the first floor with the columns dangling in space. That's his tattoo.

From: David Topete [mailto:d.topete73@gmail.com]
Sent: Wednesday, January 14, 2009 2:01 PM
To: seaint@seaint.org
Subject: Re: curved beams

was it the guggenheim they got on their forearm?

On Wed, Jan 14, 2009 at 1:50 PM, Garner, Robert <rgarner@moffattnichol.com> wrote:

Did anyone watch L.A. Ink where Kat tatoos an Architect?

From: Jimenez, Jorge A. [mailto:jajimenez@csagroup.com]
Sent: Wednesday, January 14, 2009 1:14 PM

To: seaint@seaint.org
Subject: RE: curved beams

We can ask to Stephen Hawking for an antimatter universe with other gravitational laws ideal for some architects, or help them to realize the limitations of our one.

Jorge Jimenez, PE

From: Harold Sprague [mailto:spraguehope@hotmail.com]
Sent: Wednesday, January 14, 2009 4:57 PM
To: seaint@seaint.org
Subject: RE: curved beams

There is another relatively painless method contained in Design of Welded Structures by Blodgett.

Regards, Harold Sprague

Date: Wed, 14 Jan 2009 11:37:38 -0800
From: prajendran@ymail.com
Subject: RE: curved beams
To: seaint@seaint.org

The only reference that quickly comes to my mind is AISC's "Torsion Analysis of Steel Members".

Rajendran

--- On Wed, 1/14/09, Gautam Manandhar <Gautam_Manandhar@ci.richmond.ca.us> wrote:

From: Gautam Manandhar <Gautam_Manandhar@ci.richmond.ca.us>
Subject: RE: curved beams
To: seaint@seaint.org
Date: Wednesday, January 14, 2009, 12:35 AM

List members:

I have a curved beam (horizontal). The center line of the beam layout is horizontally offset from the supporting post by about 10+ % of the span. The arch wants a channel section and will not allow a tube section. Can anyone suggest a quick method to check for flexure and torsion. DL is 480plf , LL = 800 plf. The project in under construction and the detail is due first thing to-morrow morning.

Gautam

.

Windows Live™ Hotmail®: Chat. Store. Share. Do more with mail. See how it works.

--
David Topete, SE

--
David Topete, SE

CBO Contact

Hello Engineers,

Is there a President of this organization? (Certified Building Offical)

Thanks

Antonio S. Luisoni

Consuting S.E.

Granada Hills, cA

A Good Credit Score is 700 or Above. See yours in just 2 easy steps!

RE: curved beams

First the tatoo artist couldn't figure out what the architect had drawn for his tatoo. It made absolutely no sense. When she figured it out, she realized it was not possible to do it in line work. So after figuring out what the Archie wanted, she completely redrew it for practicality, then went to work. But the Architect was afraid to let just anyone know he had a tat, so he had her stop it short just above his short-sleeve line. So you have this fantastic convoluted shape that just seems to stop with loose ends just above his sleeve line - imagine a skyscraper elevation cut off at about mid-level of the first floor with the columns dangling in space. That's his tattoo.

From: David Topete [mailto:d.topete73@gmail.com]
Sent: Wednesday, January 14, 2009 2:01 PM
To: seaint@seaint.org
Subject: Re: curved beams

was it the guggenheim they got on their forearm?

On Wed, Jan 14, 2009 at 1:50 PM, Garner, Robert <rgarner@moffattnichol.com> wrote:

Did anyone watch L.A. Ink where Kat tatoos an Architect?

From: Jimenez, Jorge A. [mailto:jajimenez@csagroup.com]
Sent: Wednesday, January 14, 2009 1:14 PM

To: seaint@seaint.org
Subject: RE: curved beams

We can ask to Stephen Hawking for an antimatter universe with other gravitational laws ideal for some architects, or help them to realize the limitations of our one.

Jorge Jimenez, PE

From: Harold Sprague [mailto:spraguehope@hotmail.com]
Sent: Wednesday, January 14, 2009 4:57 PM
To: seaint@seaint.org
Subject: RE: curved beams

There is another relatively painless method contained in Design of Welded Structures by Blodgett.

Regards, Harold Sprague

Date: Wed, 14 Jan 2009 11:37:38 -0800
From: prajendran@ymail.com
Subject: RE: curved beams
To: seaint@seaint.org

The only reference that quickly comes to my mind is AISC's "Torsion Analysis of Steel Members".

Rajendran

--- On Wed, 1/14/09, Gautam Manandhar <Gautam_Manandhar@ci.richmond.ca.us> wrote:

From: Gautam Manandhar <Gautam_Manandhar@ci.richmond.ca.us>
Subject: RE: curved beams
To: seaint@seaint.org
Date: Wednesday, January 14, 2009, 12:35 AM

List members:

I have a curved beam (horizontal). The center line of the beam layout is horizontally offset from the supporting post by about 10+ % of the span. The arch wants a channel section and will not allow a tube section. Can anyone suggest a quick method to check for flexure and torsion. DL is 480plf , LL = 800 plf. The project in under construction and the detail is due first thing to-morrow morning.

Gautam

Windows Live™ Hotmail®: Chat. Store. Share. Do more with mail. See how it works.

--
David Topete, SE

RE: Catenary

Thor,

Is the catenary sloping? Or are the supports at different levels?

Norris and Wilbur elementary structural analysis covers cables, with general
theorem for supports at different levels.

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

RE: Catenary

If you want a book - the classic reference is "Cable Structures" by Max
Irvine. I got mine from powells.com several years ago for about 10
bucks (it's a Dover soft-cover).

If you want a paper, I recommend: Peyrot, A.H., and A.M. Goulois. 1979.
"Analysis of Cable Structures". Computers and
Structures, Vol. 10. pp. 805-813. It provides a compact, closed-form,
exact solution for inclined linear-elastic catenaries. (My preference
may be biased - Alain Peyrot was my advisor in college and I have used
the equations derived in this paper many times, though I can't seem to
put my hands on the paper right now).

Have fun,
Brian

-----Original Message-----
From: Thor Tandy [mailto:vicpeng@telus.net]
Sent: Wednesday, January 14, 2009 7:23 AM
To: SEAINT
Subject: Catenary

I'm designing poles for various cable supports up a 30deg slope. I have
equations for horizontal catenary but I need a reference that shows how
cable forces vary in sloped catenary. Does anyone have such a
reference?

TIA

Thor A. Tandy P.Eng, C.Eng, Struct.Eng, MIStructE
Victoria, BC
Canada