Structural Engineering: 2008-04-06

Saturday, April 12, 2008

off-topic,was-The Boltable Embed Plate

Russel:

For me personally, please refrain from using this list serve for advertisements.

Respectfully,

Bob Freeman AIA, EIT

IDS Group, Inc.

The Boltable Embed Plate

Recently used on a local project the new Bullalo, New York Zoo their South Amarican Rainforest exibit being constructed now.

The structural engineer A. J. Petrilli P.E. says he will continue to use them where required in his future projects. ajpetrilli@jansenkiener.com

The Boltable Embed Plates save erection time by elimenating field welding to blind embed plates.

They are available from Community Steel Corp. Att: Joe Vona at jvona@communitysteel.com

If your interested let me know and I can send you via E-Mail a complete set of PDF drawings with the values both shear and tension.

Thank you

Russell L. VeRost

Friday, April 11, 2008

Pictures needed of Seismic Damage to Residential Construction

I live in an area that is right on the west edge of the San Andreas Fault – the Coachella Valley (Palm Springs California area). As much as this area is a high risk for a major seismic event, the builders, framers, owners and developers are rather complacent about the potential damage. This stems from a number of reasons including:

1. The Lander’s Earthquake in the late 80’s occurred more than 70 miles from here and the damage from the moderate seismic event caused no real damage in Palm Springs to Indio area other than merchandise falling from the shelves of stores and some minor damage to adobe structures.

2. The last recorded moderate event reaching over 6.5 on the Richter occur in 1940 as the Imperial Earthquake. Again this too far from this area and at the time, the area was undeveloped so that whatever motion may have been detected would have had little recorded effects due to sparse nature of the development of the area.

The Desert Sun and Cal Tech have been warning the residents of the area that we are long overdue for a major earthquake, but it does not seem to faze those who were not in Los Angeles or Bay areas during the moderate events since the Sylmar Earthquake in the 70’s through the Northridge quake in ’94.

When I do a remodel and inspect some of the developments constructed in the 1950’s thru the 1970’s I’ve noticed that many of the interior (and some exterior bearing walls) are secured to the slab with PAF nails. Anchor bolts are few and far between. I have a number of times run across interior partitions that support ceilings only. There may be an attic and in some cases the high-roof beams are supported by nothing more than 4x4’s at the splice that are continuous through the interior non-bearing wall and simply resting on the mud sill.

Lately , I’ve run through much opposition by the owners and their contractors who do not want to do more than they have to – in other words they don’t want to reinvent the lateral design or even the anchorage of walls bearing at least the weights of massive ceilings. In the latest remodels I’ve written the owner who I signed directly with and received authorization to design HTT-22 connectors from the posts into an epoxy connection into a continuous foundation found below the slab. This will prevent the post from walking. In the latest remodel, the owner is invest over $250K in the remodel that included my removing all interior walls (with a few exceptions) to redesign an interior post and beam kitchen / Living room open plan with stepped up ceilings. All of my beams and columns are adequately secured to the foundations that I ended up having to add, but three interior walls are constructed to either bear the load of the ceiling on the double plate of the wall or have a 2x ledgered to the double 2x top plate and studs in the wall with ceiling joists flush framed to the ledgers and secured with LUS type connectors from the early 70’s.

The problem is that the walls are secured to the foundations below the slab with PAF fasteners rather than anchor bolts. This was one of the most common causes of damage that I noted in the Northridge earthquake while I was evaluating and doing repairs. The walls sheared the PAF nails and jumped out-of-plain often bringing down ceilings, landings, stair stringers etc. In my current job, I was able to exert some authority on the job to convince the owner to do the additional work pointing out that while his HOA may be responsible for the earthquake damage to the duplex, they could argue that since he remodeled either the remodel contributed to the damage or that he had the opportunity to correct the damage when the walls were opened and exposed. I am off the hook because I put it in writing that it was necessary and an inexpensive insurance considering his investment, but I often come to a brick wall when either the builder does not believe it because they think they went through a great earthquake when Landers hit 70 miles away or that they felt Northridge knock them off their feet from 150 miles away. The idea that they have not conception of the power that those who were living in the San Fernando Valley experienced from a moderate earthquake does not exist.

I thought if I could put together examples of the various types of damage that we encountered (my pictures were accidently lost in a clean out years ago) I could have something more concrete to share with clients to convince them to put their money where it cannot be seen but will protect their investment many times over.

If you have any Jpeg or other pictures of wood frame damage (especially interior walls or in conventional prescriptive construction) that can be e-mailed, I would greatly appreciate receiving them. I will post them but mostly I will create a PDF volume that the clients (anyone’s) can use to display the damage that we expect but have never experienced in this region – especially for the thousands who spend their winter’s here from the Midwest and East coast who have not experience with earthquakes.

Please let me know if you are willing to share your photos with me. Whatever I post I will list the photographer and source on in the PDF guide so others will know where it came from.

Thanks in advance.

Dennis S. Wish, PE

California Professional Engineer

C-41250 Exp. 3/31/09

Structural Engineering Consultant

54625 Avenida Bermudas

La Quinta, CA 92253

760.564.0884 (Phone, Fax and Answering Machine)

dennis.wish@verizon.net

http://structuralist.wordpress.com

http://www.structuralist.net

Re: 3x min for conc/mas wall anch to flex diaph?

I'm sure the gang-nail truss people got that one ex-nayed...

The reason it's in the code was for 2x4 and 2x6's mainly. Nailed from above (roof nailing) and the side caused splitting.

I was okay using A35's for 2x10 and 2x12's on a masonry wall top where the rafters sit on a nailer, but even sometimes on those I would sister on a block to get (2) 2x's if they were at 24" o.c. Most plan checkers were okay with this when I explained the intent of the 3x provision.

For HD's, PHD's and whatever the new simpson hold-down is called, those are tabulated in DBL 2x's min, so I could easily and rightfully see a plan checker dis-allowing those if used on a single 2x (maybe the HD if someone did the bolt-calc).

I think clips with low forces, you're okay anchoring a 2x8 or deeper, but I would strive for 3x's and double 2x's at a minimum for anchor spacings greater than 2ft. or when using 2x6's or shallower

-gm

On Fri, Apr 11, 2008 at 1:39 PM, Gould, Diane <Diane.Gould@dgs.ca.gov> wrote:

The 1997 UBC Section 1633.2.8.1 item 5 required that wood "elements of anchorage" have the strength to take 0.85 x Fanch and have a minimum net thickness of 2.5 inches. I am at a loss to find where this requirement is included in the new code. ASCE 7-05 Section 12.11.2 addresses anchorage of concrete & masonry walls, but the 3x min requirement seems to have been dropped.

I think you would have a hard time finding hardware to fit/work with members smaller than 3x anyway and I plan to continue detailing with 3x minimum. Just curious if anyone else had noticed this or might have some background on possible reasons for this apparent omission.

Regards,

Diane C. Gould, S.E.

Senior Structural Engineer

DGS-RESD-PSB

Design Services Section

707 Third Street, Suite 4-105

West Sacramento, CA 95605

(916) 375-4219 phone

(916) 375-4916 fax

diane.gould@dgs.ca.gov

--
-gm

3x min for conc/mas wall anch to flex diaph?

The 1997 UBC Section 1633.2.8.1 item 5 required that wood “elements of anchorage” have the strength to take 0.85 x Fanch and have a minimum net thickness of 2.5 inches. I am at a loss to find where this requirement is included in the new code. ASCE 7-05 Section 12.11.2 addresses anchorage of concrete & masonry walls, but the 3x min requirement seems to have been dropped.

I think you would have a hard time finding hardware to fit/work with members smaller than 3x anyway and I plan to continue detailing with 3x minimum. Just curious if anyone else had noticed this or might have some background on possible reasons for this apparent omission.

Regards,

Diane C. Gould, S.E.

Senior Structural Engineer

DGS-RESD-PSB

Design Services Section

707 Third Street, Suite 4-105

West Sacramento, CA 95605

(916) 375-4219 phone

(916) 375-4916 fax

diane.gould@dgs.ca.gov

Re: Take a look at jaxtr!

Sadanand Ojha wrote:

jaxtr - link your phone

structure,
I am using jaxtr, and if you also sign up, we can talk for free on the phone at any time.

-Sadanand

P.S. Here is the link to sign up:
http://www.jaxtr.com/user/ticket?n=T198r2p6uqz4rg&type=joininvite

Delivered by jaxtr, Inc., 855 Oak Grove Avenue, Suite 100, Menlo Park, California 94025. Click here to stop receiving messages from this sender.

What, does this go through yer freakin' address book and spam every contact?

Not a very "professional" way to do business!

Thursday, April 10, 2008

RE: ASCE7-05 240 ft ordinary braced frames in seismic design category D?

AISC 341-05 requires the connections to fail by a ductile limit state and
requires the braces to be seismically compact. This drives you to connections
stronger than the member and for your brace to not fracture. Chevron braces
have the same requirements for ordinary or special frames.

When I took earthquake engineering I remember the professor saying the
special load combinations were put into the codes to approximate the maximum
force that could be delivered by the system.

The one benefit with ordinary braced frames now is that you could design the
connections with a envelope of member internal forces with the special load
combinations - they still have to fail by a ductile limit state. I detail my
gussets with the 2 thickness offset so why can't the building be taller than
35 feet and to meet the 70%-30% compression-tension rule.

They need to add an exception that allows OCBF's to be several stories tall
if the gussets are detailed to buckle out of plane and if 70%-30% rule is
met.

-----Original Message-----
From: Harold Sprague [mailto:spraguehope@hotmail.com]
Sent: Thursday, April 10, 2008 12:45 PM
To: seaint@seaint.org
Subject: RE: ASCE7-05 240 ft ordinary braced frames in seismic design
category D?

There has been no small effort to dump the OCBF. But there is insurrection,
dissention, and revolution in the ranks. There has not been an overwhelming
body of evidence to indicated the OCBF's are the bane of proper structural
engineering as one would theorize.

The Pre-engineered Metal Building industry will not dump the OCBF. That is
why footnote j is there. If you can qualify it for simplified design, it is
permitted. Better yet, qualify it as a nonbuilding structure and you can
dance in the streets. Check ASCE 7-05 Table 15.4-1.

The reason the OCBF was killed for most buildings is the "perception" of poor
performance and the alternative was the SCBF. Without a body of evidence to
indicate poor performance for the OCBF, the nonbuilding structures people
were able to retain it for power plants, towers and other structures where
deflection limits were driving the design as opposed to stress. The other
reason was that a lot of towers do not have gusset plates rendering the SCBF
impossible.

Regards,
Harold Sprague

________________________________

Date: Thu, 10 Apr 2008 09:51:11 -0700
From: gmse4603@gmail.com
To: seaint@seaint.org
Subject: Re: ASCE7-05 240 ft ordinary braced frames in seismic design
category D?

Doug is 100% correct on DSA's policy on OCBF's. 35 ft limit, no
exceptions and they will do everything in their power to make you abandon the
system for something more ductile.

-gm

On Wed, Apr 9, 2008 at 5:40 PM, Doug Mayer
<doug.mayer@taylorteter.com> wrote:

I attended a DSA seminar prior to the rollout of the new code
and I
remember them saying that ordinary steel braced frames were
essentially
going to the dump. The height limitation per ASCE 7-05 seems
to confirm
that statement and none of the errata that I have seen
changes that
value. Sucks.

Doug Mayer, SE
Structural Engineer

-----Original Message-----
From: Haan, Scott M POA [mailto:Scott.M.Haan@usace.army.mil]
Sent: Wednesday, April 09, 2008 5:28 PM
To: seaint@seaint.org

Subject: RE: ASCE7-05 240 ft ordinary braced frames in
seismic design
category D?

Gerard:

They had the same note in the ASCE7-02 and IBC 2000 that
allowed single
story
ordinary braced frames to be 60 feet with the 20 psf roof,
but there was
an
exception for "braced frames" to be 240 when not more than
60% of the
story
shear was on a grid and not more than 20% of the force in a
brace was
from
torsion.

Ordinary braced frames by ASCE7-02, IBC 2000, and IBC 2003
could be 240
feet
tall in seismic design category D if there was not a
torsional
irregularity
and if your grids had an even distribution of the story
shear. It
appears
maybe they don't want to allow two story ordinary braced
frames in
seismic
design category D to be taller than 35 feet in the ASCE7-05
anymore, but
you
can't tell exactly because of the poorly written wording -
maybe there
is an
errata since the printing I have.

I am wondering if there is a typo in the ASCE7-05 and whether
the code
committee really wants to hose people into using special
concentrically
braced frames for a shoe box - two or three story building
that is a bit
taller than 35 feet. I think 35 feet is too short for an
ordinary braced
frame building with a bunch of braced grids for a two, three
or four
story
building.

Scott.

-----Original Message-----
From: Gerard Madden, SE [mailto:gmse4603@gmail.com]
Sent: Wednesday, April 09, 2008 4:02 PM
To: seaint@seaint.org
Subject: Re: ASCE7-05 240 ft ordinary braced frames in
seismic design
category D?

Footnote J of Table 12.2-1 states you can increase the height
to 60 feet
for
1 story buildings with roof DL 20 psf or less for OCBF's

I think this provision superseeds footnote D in the same
table

hth,
-gm

On Wed, Apr 9, 2008 at 3:53 PM, Haan, Scott M POA
<Scott.M.Haan@usace.army.mil> wrote:

It used to be in ASCE7-02 that ordinary braced frames
were
limited to 35 feet with an exception that they could be as
high as 240 feet as long as any braced frame grid did not carry more than 60%
of the seismic forces in that direction and that not more the 20% of the
force in a braced frame was from torsion.

ASCE7-05 section 12.2.5.4's wording seems to muddy the
waters for me. It says height limits in Table 12.2-1 are permitted to be
increased from 160 feet to 240 ft in seismic design category D?

Does this mean I can can have an ordinary braced frame
in
seismic design category D with a 35 ft height limitation
increased to between 160 feet and 240 feet per ASCE 7-05?

Special braced frames and eccentrically braced frames
have a
height limit of 160 feet in seismic design category D. It
seems like the intent of ASCE 7-05 is only to allow special braced frames and
eccentrically braced frames to use the height limit exception because of the
wording "increased from 160 feet to 240 feet."

Thanks.
Scott

________________________________

Pack up or back up-use SkyDrive to transfer files or keep extra copies. Learn
how.
<hthttp://www.windowslive.com/skydrive/overview.html?ocid=TXT_TAGLM_WL_Refres
h_skydrive_packup_042008>

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RE: ASCE7-05 240 ft ordinary braced frames in seismic design category D?

There has been no small effort to dump the OCBF. But there is insurrection, dissention, and revolution in the ranks. There has not been an overwhelming body of evidence to indicated the OCBF's are the bane of proper structural engineering as one would theorize.

The Pre-engineered Metal Building industry will not dump the OCBF. That is why footnote j is there. If you can qualify it for simplified design, it is permitted. Better yet, qualify it as a nonbuilding structure and you can dance in the streets. Check ASCE 7-05 Table 15.4-1.

The reason the OCBF was killed for most buildings is the "perception" of poor performance and the alternative was the SCBF. Without a body of evidence to indicate poor performance for the OCBF, the nonbuilding structures people were able to retain it for power plants, towers and other structures where deflection limits were driving the design as opposed to stress. The other reason was that a lot of towers do not have gusset plates rendering the SCBF impossible.

Regards,
Harold Sprague

Date: Thu, 10 Apr 2008 09:51:11 -0700
From: gmse4603@gmail.com
To: seaint@seaint.org
Subject: Re: ASCE7-05 240 ft ordinary braced frames in seismic design category D?

Doug is 100% correct on DSA's policy on OCBF's. 35 ft limit, no exceptions and they will do everything in their power to make you abandon the system for something more ductile.

-gm

On Wed, Apr 9, 2008 at 5:40 PM, Doug Mayer <doug.mayer@taylorteter.com> wrote:

I attended a DSA seminar prior to the rollout of the new code and I
remember them saying that ordinary steel braced frames were essentially
going to the dump. The height limitation per ASCE 7-05 seems to confirm
that statement and none of the errata that I have seen changes that
value. Sucks.

Doug Mayer, SE
Structural Engineer

-----Original Message-----
From: Haan, Scott M POA [mailto:Scott.M.Haan@usace.army.mil]
Sent: Wednesday, April 09, 2008 5:28 PM
To: seaint@seaint.org

Subject: RE: ASCE7-05 240 ft ordinary braced frames in seismic design
category D?

Gerard:

They had the same note in the ASCE7-02 and IBC 2000 that allowed single
story
ordinary braced frames to be 60 feet with the 20 psf roof, but there was
an
exception for "braced frames" to be 240 when not more than 60% of the
story
shear was on a grid and not more than 20% of the force in a brace was
from
torsion.

Ordinary braced frames by ASCE7-02, IBC 2000, and IBC 2003 could be 240
feet
tall in seismic design category D if there was not a torsional
irregularity
and if your grids had an even distribution of the story shear. It
appears
maybe they don't want to allow two story ordinary braced frames in
seismic
design category D to be taller than 35 feet in the ASCE7-05 anymore, but
you
can't tell exactly because of the poorly written wording - maybe there
is an
errata since the printing I have.

I am wondering if there is a typo in the ASCE7-05 and whether the code
committee really wants to hose people into using special concentrically
braced frames for a shoe box - two or three story building that is a bit
taller than 35 feet. I think 35 feet is too short for an ordinary braced
frame building with a bunch of braced grids for a two, three or four
story
building.

Scott.

-----Original Message-----
From: Gerard Madden, SE [mailto:gmse4603@gmail.com]
Sent: Wednesday, April 09, 2008 4:02 PM
To: seaint@seaint.org
Subject: Re: ASCE7-05 240 ft ordinary braced frames in seismic design
category D?

Footnote J of Table 12.2-1 states you can increase the height to 60 feet
for
1 story buildings with roof DL 20 psf or less for OCBF's

I think this provision superseeds footnote D in the same table

hth,
-gm

On Wed, Apr 9, 2008 at 3:53 PM, Haan, Scott M POA
<Scott.M.Haan@usace.army.mil> wrote:

It used to be in ASCE7-02 that ordinary braced frames were
limited to 35 feet with an exception that they could be as high as 240 feet as long as any braced frame grid did not carry more than 60% of the seismic forces in that direction and that not more the 20% of the force in a braced frame was from torsion.

ASCE7-05 section 12.2.5.4's wording seems to muddy the waters for me. It says height limits in Table 12.2-1 are permitted to be increased from 160 feet to 240 ft in seismic design category D?

Does this mean I can can have an ordinary braced frame in
seismic design category D with a 35 ft height limitation increased to between 160 feet and 240 feet per ASCE 7-05?

Special braced frames and eccentrically braced frames have a
height limit of 160 feet in seismic design category D. It seems like the intent of ASCE 7-05 is only to allow special braced frames and eccentrically braced frames to use the height limit exception because of the wording "increased from 160 feet to 240 feet."

Thanks.
Scott

Pack up or back up–use SkyDrive to transfer files or keep extra copies. Learn how.

Re: Concentrated Loads on Plywood Floors...

Benjamin Maxwell wrote:
> Listers,
> .......................
> happy to volunteer. Besides being a life-safety issue, losing wine
> is a major life-quality concern. You Australians need to learn how to
> maintain your infrastructure. You should just follow the
> American example with respect to our highway bridges. Ha!!!!!!
>

Work out a trade. You go down to look at wineries and Conrad comes up
to look at our bridges....

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

Re: ASCE7-05 240 ft ordinary braced frames in seismic design category D?

Doug is 100% correct on DSA's policy on OCBF's. 35 ft limit, no exceptions and they will do everything in their power to make you abandon the system for something more ductile.

-gm

On Wed, Apr 9, 2008 at 5:40 PM, Doug Mayer <doug.mayer@taylorteter.com> wrote:

I attended a DSA seminar prior to the rollout of the new code and I
remember them saying that ordinary steel braced frames were essentially
going to the dump. The height limitation per ASCE 7-05 seems to confirm
that statement and none of the errata that I have seen changes that
value. Sucks.

Doug Mayer, SE
Structural Engineer

-----Original Message-----
From: Haan, Scott M POA [mailto:Scott.M.Haan@usace.army.mil]
Sent: Wednesday, April 09, 2008 5:28 PM
To: seaint@seaint.org

Subject: RE: ASCE7-05 240 ft ordinary braced frames in seismic design
category D?

Gerard:

They had the same note in the ASCE7-02 and IBC 2000 that allowed single
story
ordinary braced frames to be 60 feet with the 20 psf roof, but there was
an
exception for "braced frames" to be 240 when not more than 60% of the
story
shear was on a grid and not more than 20% of the force in a brace was
from
torsion.

Ordinary braced frames by ASCE7-02, IBC 2000, and IBC 2003 could be 240
feet
tall in seismic design category D if there was not a torsional
irregularity
and if your grids had an even distribution of the story shear. It
appears
maybe they don't want to allow two story ordinary braced frames in
seismic
design category D to be taller than 35 feet in the ASCE7-05 anymore, but
you
can't tell exactly because of the poorly written wording - maybe there
is an
errata since the printing I have.

I am wondering if there is a typo in the ASCE7-05 and whether the code
committee really wants to hose people into using special concentrically
braced frames for a shoe box - two or three story building that is a bit
taller than 35 feet. I think 35 feet is too short for an ordinary braced
frame building with a bunch of braced grids for a two, three or four
story
building.

Scott.

-----Original Message-----
From: Gerard Madden, SE [mailto:gmse4603@gmail.com]
Sent: Wednesday, April 09, 2008 4:02 PM
To: seaint@seaint.org
Subject: Re: ASCE7-05 240 ft ordinary braced frames in seismic design
category D?

Footnote J of Table 12.2-1 states you can increase the height to 60 feet
for
1 story buildings with roof DL 20 psf or less for OCBF's

I think this provision superseeds footnote D in the same table

hth,
-gm

On Wed, Apr 9, 2008 at 3:53 PM, Haan, Scott M POA
<Scott.M.Haan@usace.army.mil> wrote:

It used to be in ASCE7-02 that ordinary braced frames were
limited to
35 feet
with an exception that they could be as high as 240 feet as long
as
any
braced frame grid did not carry more than 60% of the seismic
forces
in that
direction and that not more the 20% of the force in a braced
frame
was from
torsion.

ASCE7-05 section 12.2.5.4's wording seems to muddy the waters
for me.
It
says height limits in Table 12.2-1 are permitted to be increased
from
160
feet to 240 ft in seismic design category D?

Does this mean I can can have an ordinary braced frame in
seismic
design
category D with a 35 ft height limitation increased to between
160
feet and
240 feet per ASCE 7-05?

Special braced frames and eccentrically braced frames have a
height
limit of
160 feet in seismic design category D. It seems like the intent
of
ASCE 7-05
is only to allow special braced frames and eccentrically braced
frames to use
the height limit exception because of the wording "increased
from 160
feet to
240 feet."

Thanks.
Scott

******* ****** ******* ******** ******* ******* ******* ***
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--
-gm

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Visit our new website at www.taylorteter.com

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* This email was sent to you via Structural Engineers
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--
-gm

RE: Concentrated Loads on Plywood Floors...

Listers,

Thanks to all who pitched in regarding my plywood floor issue. I've determined that I would probably be okay in the short term, but that deflection and sag serviceability would be a concern. Unfortunately for me, the layout does not lend itself to laying out an additional plywood layer above the floor due to exiting requirements and tripping hazard.

Conrad, I hadn't heard about the Wirra Wirra winery fermentatoin and holding tank collapse, but I saw on AdelaideNow that two workers were injured - not to mention the travesty of losing all that good wine. Do you guys have the need for a structural engineer to tour all of the wineries in the Barossa Valley to check for fatigue issues and other structural deficiencies? I'd be happy to volunteer. Besides being a life-safety issue, losing wine is a major life-quality concern. You Australians need to learn how to maintain your infrastructure. You should just follow the American example with respect to our highway bridges. Ha!!!!!!

Conrad Harrison <sch.tectonic@bigpond.com> wrote:

Ben

Here most manufacturers catalogues have load tables for the plywood. But what they call a concentrated load is actually a linear load across the width of the beam like panel being tested. In the past not been able to get any information to check suitability for real point loads from legs castors and wheels.

So for fixed cabinets tend to place a batten/spreader under the legs to transfer the load back onto the floor joists. For castors recommend not to use unless the owners already have experience with an existing floor: the plywood can creep and sag between the joists if keep rolling heavy loads over it.

Have to get back to you on the wineries: Clare and the Barossa valley are the main regions.

By the way did news of the collapse of the fermenting and holding tanks, and support stand at the Wirra Wirra winery make it to the USA.

Regards

Conrad Harrison

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

mailto:sch.tectonic@bigpond.com

Adelaide

South Australia

From: Benjamin Maxwell [mailto:enginerd666@yahoo.com]
Sent: Tuesday, 8 April 2008 02:06
To: seaint@seaint.org
Subject: Concentrated Loads on Plywood Floors...

Listerineros,

I am in need of some recommendations or references for determining the structural adequacy of concentrated loads on plywood floors.

I have a condition where my client wishes to locate several large security storage cabinets (they weigh upwards of 600 pounds empty) on the floor of a modular trailer. The cabinets are supported on 4 lovely, miniature feet - perhaps measuring one inch square on a extremely hot day. Additionally, I don't have a good sense from the client on how much the contents could weight - perhaps 300 to 400 pounds based on my discussions with the group managing the cabinet contents.

So, I have concerns with the local effects on the plywood and the overall span, especially while maintaining the same 50 psf live load rating.

To make things more fun, strengthening below the floor is not an option. It's either green light or red light in this case.

I'll let Conrad know in advance that I think I've seen such limitations in both the Australian and New Zealand codes, but have not had as much luck using my available APA references and Google for U.S. codes. When are we northern hemispherians going to learn? Also, I'd greatly appreciate Conrad's recommendations on good, small wineries from the Aidelade area just as much as I appreciate his engineering recommendations and thoughts.

Thanks in advance!

-Ben Maxwell

Benjamin H. Maxwell, S.E.

You rock. That's why Blockbuster's offering you one month of Blockbuster Total Access, No Cost.

Benjamin H. Maxwell, S.E.

__________________________________________________
Do You Yahoo!?
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Wednesday, April 9, 2008

RE: ASCE7-05 240 ft ordinary braced frames in seismic design category D?

I should mention that AISC 341-05 7.1 forces your connection to be controlled
by a ductile limit state which means for an ordinary braced frame normally
the connection is probably going to be as strong as the brace in tension
anyway. So why can't a two story ordinary braced frame be 36 feet tall?

-----Original Message-----
From: Haan, Scott M POA
Sent: Wednesday, April 09, 2008 5:12 PM
To: 'seaint@seaint.org'
Subject: RE: ASCE7-05 240 ft ordinary braced frames in seismic design
category D?

Follow this code path:
Table 12.2-1 --> Building Frame System B. 1. ordinary steel braced frame
seismic design category D height <35 feet. - note d for seismic design
category D -->"12.2.5.4 Increased height limits for steel braced frames...
The height limits in Table 12.2-1 are permitted to be increased from 160 to
240 feet for structures assigned to seismic design category D or E..." They
don't mention it has to be a special frame - leaves a lot open to
interpretation and I must be a structural engineer because what I think it
means affects my state of harmony.

With ordinary braced frames you are allowed to design the connections for the
special load combinations and there aren't the stupid protected zones. That
is why people would want to use them on a three story building.

They destroyed the benefit of chevron bracing in ordinary braced frames in
AISC341-05. They already reduced the R to 3.25 for ordinary braced frames
and the OMEGAo=2 so you are practically designing the stupid connections to
be elastic. You can pick the envelope internal force out of your model and
plug it into a connection spreadsheet. I already detail them so the gussets
can buckle, why can't it be three stories? -- it is !#$%@%^$^&*% stupid. Also
I don't want to argue it with someone if I write an RFP.

-----Original Message-----
From: Doug Mayer [mailto:doug.mayer@taylorteter.com]
Sent: Wednesday, April 09, 2008 4:40 PM
To: seaint@seaint.org
Subject: RE: ASCE7-05 240 ft ordinary braced frames in seismic design
category D?

I attended a DSA seminar prior to the rollout of the new code and I remember
them saying that ordinary steel braced frames were essentially going to the
dump. The height limitation per ASCE 7-05 seems to confirm that statement
and none of the errata that I have seen changes that value. Sucks.

Doug Mayer, SE
Structural Engineer

Gerard:

They had the same note in the ASCE7-02 and IBC 2000 that allowed single story
ordinary braced frames to be 60 feet with the 20 psf roof, but there was an
exception for "braced frames" to be 240 when not more than 60% of the story
shear was on a grid and not more than 20% of the force in a brace was from
torsion.

Ordinary braced frames by ASCE7-02, IBC 2000, and IBC 2003 could be 240 feet
tall in seismic design category D if there was not a torsional irregularity
and if your grids had an even distribution of the story shear. It appears
maybe they don't want to allow two story ordinary braced frames in seismic
design category D to be taller than 35 feet in the ASCE7-05 anymore, but you
can't tell exactly because of the poorly written wording - maybe there is an
errata since the printing I have.

I am wondering if there is a typo in the ASCE7-05 and whether the code
committee really wants to hose people into using special concentrically
braced frames for a shoe box - two or three story building that is a bit
taller than 35 feet. I think 35 feet is too short for an ordinary braced
frame building with a bunch of braced grids for a two, three or four story
building.

Scott.

-----Original Message-----
From: Gerard Madden, SE [mailto:gmse4603@gmail.com]
Sent: Wednesday, April 09, 2008 4:02 PM
To: seaint@seaint.org
Subject: Re: ASCE7-05 240 ft ordinary braced frames in seismic design
category D?

Footnote J of Table 12.2-1 states you can increase the height to 60 feet for
1 story buildings with roof DL 20 psf or less for OCBF's

I think this provision superseeds footnote D in the same table

hth,
-gm

On Wed, Apr 9, 2008 at 3:53 PM, Haan, Scott M POA
<Scott.M.Haan@usace.army.mil> wrote:

It used to be in ASCE7-02 that ordinary braced frames were limited to
35 feet
with an exception that they could be as high as 240 feet as long as
any
braced frame grid did not carry more than 60% of the seismic forces
in that
direction and that not more the 20% of the force in a braced frame
was from
torsion.

ASCE7-05 section 12.2.5.4's wording seems to muddy the waters for me.
It
says height limits in Table 12.2-1 are permitted to be increased from
160
feet to 240 ft in seismic design category D?

Does this mean I can can have an ordinary braced frame in seismic
design
category D with a 35 ft height limitation increased to between 160
feet and
240 feet per ASCE 7-05?

Special braced frames and eccentrically braced frames have a height
limit of
160 feet in seismic design category D. It seems like the intent of
ASCE 7-05
is only to allow special braced frames and eccentrically braced
frames to use
the height limit exception because of the wording "increased from 160
feet to
240 feet."

Thanks.
Scott

******* ****** ******* ******** ******* ******* ******* ***
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******* ****** ****** ****** ******* ****** ****** ******** Visit our new
website at www.taylorteter.com

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

RE: ASCE7-05 240 ft ordinary braced frames in seismic design category D?

I attended a DSA seminar prior to the rollout of the new code and I remember
them saying that ordinary steel braced frames were essentially going to the
dump. The height limitation per ASCE 7-05 seems to confirm that statement
and none of the errata that I have seen changes that value. Sucks.

Doug Mayer, SE
Structural Engineer

Gerard:

Scott.

Footnote J of Table 12.2-1 states you can increase the height to 60 feet for
1 story buildings with roof DL 20 psf or less for OCBF's

I think this provision superseeds footnote D in the same table

hth,
-gm

On Wed, Apr 9, 2008 at 3:53 PM, Haan, Scott M POA
<Scott.M.Haan@usace.army.mil> wrote:

*
* 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

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

--
-gm

******* ****** ****** ****** ******* ****** ****** ******** Visit our new
website at www.taylorteter.com

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

RE: ASCE7-05 240 ft ordinary braced frames in seismic design category D?

I attended a DSA seminar prior to the rollout of the new code and I
remember them saying that ordinary steel braced frames were essentially
going to the dump. The height limitation per ASCE 7-05 seems to confirm
that statement and none of the errata that I have seen changes that
value. Sucks.

Doug Mayer, SE
Structural Engineer

Gerard:

They had the same note in the ASCE7-02 and IBC 2000 that allowed single
story
ordinary braced frames to be 60 feet with the 20 psf roof, but there was
an
exception for "braced frames" to be 240 when not more than 60% of the
story
shear was on a grid and not more than 20% of the force in a brace was
from
torsion.

Ordinary braced frames by ASCE7-02, IBC 2000, and IBC 2003 could be 240
feet
tall in seismic design category D if there was not a torsional
irregularity
and if your grids had an even distribution of the story shear. It
appears
maybe they don't want to allow two story ordinary braced frames in
seismic
design category D to be taller than 35 feet in the ASCE7-05 anymore, but
you
can't tell exactly because of the poorly written wording - maybe there
is an
errata since the printing I have.

Scott.

Footnote J of Table 12.2-1 states you can increase the height to 60 feet
for
1 story buildings with roof DL 20 psf or less for OCBF's

I think this provision superseeds footnote D in the same table

hth,
-gm

On Wed, Apr 9, 2008 at 3:53 PM, Haan, Scott M POA
<Scott.M.Haan@usace.army.mil> wrote:

It used to be in ASCE7-02 that ordinary braced frames were
limited to
35 feet
with an exception that they could be as high as 240 feet as long
as
any
braced frame grid did not carry more than 60% of the seismic
forces
in that
direction and that not more the 20% of the force in a braced
frame
was from
torsion.

ASCE7-05 section 12.2.5.4's wording seems to muddy the waters
for me.
It
says height limits in Table 12.2-1 are permitted to be increased
from
160
feet to 240 ft in seismic design category D?

Does this mean I can can have an ordinary braced frame in
seismic
design
category D with a 35 ft height limitation increased to between
160
feet and
240 feet per ASCE 7-05?

Special braced frames and eccentrically braced frames have a
height
limit of
160 feet in seismic design category D. It seems like the intent
of
ASCE 7-05
is only to allow special braced frames and eccentrically braced
frames to use
the height limit exception because of the wording "increased
from 160
feet to
240 feet."

Thanks.
Scott

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

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

--
-gm

******* ****** ****** ****** ******* ****** ****** ********
Visit our new website at www.taylorteter.com

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

RE: ASCE7-05 240 ft ordinary braced frames in seismic design category D?

Will:

I think this is what ASCE7-05 seems to be shooting for but the wording is
poor and I don't like it. I wonder if there is an errata on this?

It seems ridiculous to me that you can't use an ordinary steel braced frame
in a shoe box two story building that is 36 feet tall.

Scott.

-----Original Message-----
From: Will Haynes [mailto:gtg740p@gmail.com]
Sent: Wednesday, April 09, 2008 4:06 PM
To: seaint@seaint.org
Subject: Re: ASCE7-05 240 ft ordinary braced frames in seismic design
category D?

I also think the intent is that the braced frames which are indicated in the
table as limited to 160 ft are allowed to be increased to 240 ft, not the
ones that are listed in the table as 35 ft (the ordinary frames).

Will

On Wed, Apr 9, 2008 at 6:53 PM, Haan, Scott M POA
<Scott.M.Haan@usace.army.mil> wrote:
> It used to be in ASCE7-02 that ordinary braced frames were limited to
> 35 feet with an exception that they could be as high as 240 feet as
> long as any braced frame grid did not carry more than 60% of the
> seismic forces in that direction and that not more the 20% of the
> force in a braced frame was from torsion.
>
> ASCE7-05 section 12.2.5.4's wording seems to muddy the waters for me.
> It says height limits in Table 12.2-1 are permitted to be increased
> from 160 feet to 240 ft in seismic design category D?
>
> Does this mean I can can have an ordinary braced frame in seismic
> design category D with a 35 ft height limitation increased to between
> 160 feet and 240 feet per ASCE 7-05?
>
> Special braced frames and eccentrically braced frames have a height
> limit of 160 feet in seismic design category D. It seems like the
> intent of ASCE 7-05 is only to allow special braced frames and
> eccentrically braced frames to use the height limit exception because
> of the wording "increased from 160 feet to 240 feet."
>
> Thanks.
> Scott
>
> ******* ****** ******* ******** ******* ******* ******* ***
> * 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
> ******* ****** ****** ****** ******* ****** ****** ********
>

--
Will H.

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

RE: ASCE7-05 240 ft ordinary braced frames in seismic design category D?

Gerard:

Scott.

Footnote J of Table 12.2-1 states you can increase the height to 60 feet for
1 story buildings with roof DL 20 psf or less for OCBF's

I think this provision superseeds footnote D in the same table

hth,
-gm

On Wed, Apr 9, 2008 at 3:53 PM, Haan, Scott M POA
<Scott.M.Haan@usace.army.mil> wrote:

*
* 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

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

--
-gm

Re: ASCE7-05 240 ft ordinary braced frames in seismic design category D?

I also think the intent is that the braced frames which are indicated
in the table as limited to 160 ft are allowed to be increased to 240
ft, not the ones that are listed in the table as 35 ft (the ordinary
frames).

Will

On Wed, Apr 9, 2008 at 6:53 PM, Haan, Scott M POA
<Scott.M.Haan@usace.army.mil> wrote:
> It used to be in ASCE7-02 that ordinary braced frames were limited to 35 feet
> with an exception that they could be as high as 240 feet as long as any
> braced frame grid did not carry more than 60% of the seismic forces in that
> direction and that not more the 20% of the force in a braced frame was from
> torsion.
>
> ASCE7-05 section 12.2.5.4's wording seems to muddy the waters for me. It
> says height limits in Table 12.2-1 are permitted to be increased from 160
> feet to 240 ft in seismic design category D?
>
> Does this mean I can can have an ordinary braced frame in seismic design
> category D with a 35 ft height limitation increased to between 160 feet and
> 240 feet per ASCE 7-05?
>
> Special braced frames and eccentrically braced frames have a height limit of
> 160 feet in seismic design category D. It seems like the intent of ASCE 7-05
> is only to allow special braced frames and eccentrically braced frames to use
> the height limit exception because of the wording "increased from 160 feet to
> 240 feet."
>
> Thanks.
> Scott
>
> ******* ****** ******* ******** ******* ******* ******* ***
> * 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:
> *
> *

--
Will H.

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

Re: ASCE7-05 240 ft ordinary braced frames in seismic design category D?

Footnote J of Table 12.2-1 states you can increase the height to 60 feet for 1 story buildings with roof DL 20 psf or less for OCBF's

I think this provision superseeds footnote D in the same table

hth,
-gm

On Wed, Apr 9, 2008 at 3:53 PM, Haan, Scott M POA <Scott.M.Haan@usace.army.mil> wrote:

It used to be in ASCE7-02 that ordinary braced frames were limited to 35 feet
with an exception that they could be as high as 240 feet as long as any
braced frame grid did not carry more than 60% of the seismic forces in that
direction and that not more the 20% of the force in a braced frame was from
torsion.

ASCE7-05 section 12.2.5.4's wording seems to muddy the waters for me. It
says height limits in Table 12.2-1 are permitted to be increased from 160
feet to 240 ft in seismic design category D?

Does this mean I can can have an ordinary braced frame in seismic design
category D with a 35 ft height limitation increased to between 160 feet and
240 feet per ASCE 7-05?

Special braced frames and eccentrically braced frames have a height limit of
160 feet in seismic design category D. It seems like the intent of ASCE 7-05
is only to allow special braced frames and eccentrically braced frames to use
the height limit exception because of the wording "increased from 160 feet to
240 feet."

Thanks.
Scott

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

--
-gm

ASCE7-05 240 ft ordinary braced frames in seismic design category D?

ASCE7-05 section 12.2.5.4's wording seems to muddy the waters for me. It
says height limits in Table 12.2-1 are permitted to be increased from 160
feet to 240 ft in seismic design category D?

Does this mean I can can have an ordinary braced frame in seismic design
category D with a 35 ft height limitation increased to between 160 feet and
240 feet per ASCE 7-05?

Special braced frames and eccentrically braced frames have a height limit of
160 feet in seismic design category D. It seems like the intent of ASCE 7-05
is only to allow special braced frames and eccentrically braced frames to use
the height limit exception because of the wording "increased from 160 feet to
240 feet."

Thanks.
Scott

Tuesday, April 8, 2008

AASHTO Bridge L > 240'

I'm dealing with a steel I-girder bridge where one span is greater than 240' (280' actual). However, the distribution factor limits the maximum span to 240'.

Certainly there are plenty of typical steel plate girder bridges with spans > 240'. What is done to calculate the distribution factor for these bridges?

Residential Project in Toronto, Canada

Fellow engineers,

I would like to contact a knowledgeable engineer in the Toronto area for a small residential project. The project involves a 100 year old half duplex which seems to have a settlement problem which may be related to basement excavation in the other half duplex.The client/owner will be the daughter of an architect client/friend of mine (for more than 20 years). My friend is visiting in Toronto for the next 3 or 4 days.

Please reply personally so as to not bother others on SEAINT list.

Regards,

H. Daryl Richardson

Take a look at jaxtr!

structure,

I am using jaxtr, and if you also sign up, we can talk for free on the phone at any time.

-Sadanand

P.S. Here is the link to sign up:
http://www.jaxtr.com/user/ticket?n=T198r2p6uqz4rg&type=joininvite