Structural Engineering: 2008-08-17

Saturday, August 23, 2008

RE: Rho, Rho, Rho your boat (foundation)

Perhaps you could make the argument that rho should not apply to a mat foundation - but what about a steel braced frame system with isolated footings? An increase in brace forces would increase loads on footings.

Perhaps the code could be refined to address this - but a more refined code is also a more complex code! Do we want to keep adding complexity to refine each individual design?

Bill Sherman

CH2M HILL / DEN

720-286-2792

From: Garner, Robert [mailto:rgarner@moffattnichol.com]
Sent: Tuesday, August 19, 2008 11:31 AM
To: seaint@seaint.org
Subject: RE: Rho, Rho, Rho your boat (foundation)

Thank you all for your replies. As with many aspects of the Code, this looks like one where it's best to "Just do it", and I will henceforth. "I'm trying to keep my mind right, boss".

Although I'm still looking for the logic - if you have a lack of redundancy in your framing system that could lead to a possible failure of the framing system, how would that lead to a possible failure of the foundation, thus requiring an increase factor for the foundation? It seems you are making the foundation stronger to make up for a deficiency in a separate structural component. I can see a need for foundation redundancy but only if the foundation itself has some deficiency that makes you need an additional reliability factor. I see rho as an assurance factor for the framing itself; a penalty factor on the framing some have called it. It is related to the framing, some configurations of which have proven unreliable. But foundations have not been proven to need some means of redundancy, have they?

Not meaning to argue, just looking for engineering logic.

Bob G.

From: Garner, Robert [mailto:rgarner@moffattnichol.com]
Sent: Tuesday, August 19, 2008 9:22 AM
To: seaint@seaint.org
Subject: Rho, Rho, Rho your boat (foundation)

I'm designing a steel framed structure in Seismic Category D. For the steel framing, Rho will be 1.3. For the foundation (a concrete mat foundation), we are using a Rho of 1.0 - our reasoning being that the purpose of Rho is to assure that no single seismic force resisting element above the foundation (the building frames) will likely fail in an earthquake. Nowhere in the Codes can I find a statement that Rho is to be applied to the foundation. Can anyone challenge me on this with a Code quote or logical argument?

Thanks for any help you can offer.

Bob Garner, S.E.

R. Garner

Moffatt & Nichol

Tel.: (619) 220-6050

Fax.: (619) 220-6055

e-mail: rgarner@moffattnichol.com

Friday, August 22, 2008

re: CMU bar locations

Arunkumar,

I believe what you are asking is are you required to have a doweled bar into the footing, which laps with the vertical wall bars, at every vertical bar location? This is of course assuming as you stated a standard wall with pin-pin modeling, so the theoretical moment will be zero at the footing. Of course I have always thought that by hooking the bars into the footing and fully lapping the vertical bars, you are creating at least a partially fixed connection at the footing (that is neither here nor there).

This is of course the standard detail that I assume we all use on our drawings, but this does come up from time to time in renovation/code upgrade jobs, as well as construction errors in dowel placements. This is covered by ACI 530 2.1.10.4.1.3 as well as 2.1.10.4.2 (geesh what is this the Dewey decimal system??).

“When a wall or other flexural member is part of a primary lateral resisting system, at least 25% of the positive moment reinf. Shall extend into the support and be anchored to develop a stress equal to the Fs in tension.”

I have always interpreted that to mean every 4^th bar MUST be fully developed into the footing.

2.1.10.7.1.2- allows bars that are lap spliced to be spaced up to 8” or 1/5 of the required lap (max).

2.1.10.7.1.2 commentary (CC-38) allows for bars to be lapped in ADJACENT cells, if certain requirements are met. I personally have never done this but under the right circumstances ACI allows it… May be useful in a renovation/retrofit situation.

HTH,

Andrew Kester, PE

ADK Structural Engineering

Orlando, FL

I just done a ICF wall design with the boundary conditions at floor level

and foundations as pinned. Because of Simply supported action the rebar

calculated at mid point. Calculated rebar is given in full wall height

without curtailment. While calculating dowel bars as per ACI Min requirement

and by Shear friction. It is Less than Minimum requirement. Is it Dowel bar

locations should match with Main rebar location everywhere. Can anyone

suggest me in this context.

Regards

ARUNKUMAR C

RE: Is this news?

I participated on a WTC panel in New York in 2002 discussing WTC. WTC 7 was a bit of an issue in that there was no significant impact from airplanes or WTC 1 or WTC 2 to cause the collapse. There were a lot of very sharp people that looked into the collapse including Arup engineers, Ron Hamburger, and Gene Corley to name a few. As usual, I was like a kid studying at the knee of the great ones. Being on the panel just gave me a good seat.

The investigators had a pretty good idea about what happened to WTC 7, but it took a while to sort it all out. It was troubling to the extent that One Meridian and First Interstate were among the classic high rise fires that had devastating long lasting fires, but no collapse.

WTC 7 was problematic because it did not take that long (relatively speaking) for the fire to cause collapse. And it was the first high rise collapse caused by a fire. The crux was 2 fold. One - the transfer truss was acting to transmit column loads and two - the fire proofing of the truss may have had holidays due to construction activities. There was fuel in the basement that was the source of the fire, and once the truss local temperatures achieved the point to initiate yielding, there was no stopping it.

This issue had the potential to legitimately change the building and fire codes. WTC 1 & 2 were anomalies. We are not going to make airplane impact a design load case for every building over 10 stories high. WTC 7 had some legitimate building code concerns.

Regards,
Harold Sprague

> From: mblangy@satco-inc.com
> To: seaint@seaint.org
> Subject: Is this news?
> Date: Thu, 21 Aug 2008 12:08:25 -0700
>
> http://www.breitbart.com/article.php?id=D92MQLDG0&show_article=1
>
>
>
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Re: South Australia practices

Conrad,
We don't use the term building surveyor here in the great white north.
I have heard the term before but always associated it with the term
"quantity surveyor" which we hear occasionally from Brits. What is a
building surveyor and what are his qualifications? You do distinguish
between an engineer and a building surveyor so what does the latter do?
TIA
Gary

Conrad Harrison wrote:
> Bill,
>
> In South Australia development approval comprises of two parts:
>
> 1) Provisional Development Plan consent
> 2) Provisional building Rules consent
>
> Only the local councils (AHJ) can grant development approval, and only once
> the two consents have been granted. The assessment of building rules is
> usually by building surveyors, a few are architects and a few are engineers,
> most are not.
>
> As I understand it, in the past people could simply go to local council and
> ask what was required and they would be told what to do. Not sure how far
> back that was, but the current development act was introduced in 1993, and I
> believe the prior act required submission of structural calculations. When
> it was introduced private certifiers were also introduced, and many councils
> now send applications out to private certifiers for assessment: building
> departments have shrunk in size. Private certifiers are registered building
> surveyors, and I believe they have to also be either architects or
> engineers. Private certifiers can only grant approval for building rules,
> and building permit is not issued until get full development approval.
>
> The building surveyor is not permitted to recommend design-solutions, they
> have to remain independent. I believe at some point in the past a few
> councils were sued because of faulty footings on reactive clay soils:
> council is always there, other parties aren't.
>
> What it means is if something is undersized the building surveyor cannot say
> what size will be approved: they can only reiterate the requirements of the
> building rules.
>
> Also the development regulations require that the structural provisions of
> the building code of Australia (BCA) are assessed by an independent
> technical expert. At present however the definition of such is simply a
> person with a 4 year B.Eng in Civil Engineering and a few years of
> experience: it doesn't require registration on the national professional
> engineers register (NPER). If the building surveyor is an engineer then they
> can assess the structural provisions. Most building surveyors are not
> engineers so most councils send development applications out to private
> consulting engineers for structural assessment. These consultants usually
> request the submission of engineering calculations. That is not really the
> intent of the act.
>
> A building surveyor is permitted to accept in good faith a certificate from
> an independent technical expert, and is also required to seek such
> certificates if aspects of a development proposal are beyond their scope of
> competence.
>
> So sometimes instead of asking for engineering calculations they will simply
> ask for a certificate of an independent technical expert. If an engineer
> specialises in a particular area of practice then they can simply look at
> something and say it is similar to a 100 other projects, and certify it. But
> if the proposal is deficient they cannot advise or specify the requirements
> to make it acceptable.
>
> In which case they remove the reference to independent technical expert and
> issue a certificate of structural adequacy with conditions. If it is simple
> the engineer representing the AHJ will accept that without calculations, if
> not simple then may request the calculations or other evidence to support.
> {On the other hand the AHJ's request for a certificate makes it sound like a
> simple exercise to the owner of the building.}
>
> The building code of Australia (BCA) requires evidence-of-suitability, but
> indicates that a certificate from a suitably qualified person is adequate
> evidence. (NPER is called up as one option of suitably qualified, but not
> necessary)
>
> To me it seems that in practice there are double standards. The building
> surveyors do a lot of the assessment themselves without calculations or
> other documentary evidence: access/egress requirements, fire rated
> construction, timber framing and more. Not all of this is simple
> prescriptive comparative checks, it requires some effort and justification.
> They do not ask designers to submit calculations for such things: the
> building surveyor does what ever is required.
>
> But structural even if building surveyor is an engineer and able to make the
> assessment, they still want some calculations submitted.
>
> The issue I have with that is: in many cases it is a waste of time and
> paper, and waste of space to store the paper, especially for those
> situations where the calculations are just tedious repetition to satisfy a
> paper trail. Further more the requirement is technical check: does the
> proposal comply with the code. According to some reports, often only an
> arithmetical check is carried out: relevance and deficiencies in the
> calculations not understood or recognised.
>
> If the technical experts were selected correctly, then they would have
> appropriate tools to review the proposals in the shortest time frame
> possible. Given such tools it is a waste of time to decipher hand written
> scribble, when can check the specification directly.
>
> The intent of the 1993 development act was to speed up approval. My view is
> that the designer only needs to submit their calculations, when the checker
> considers there is a non-compliance, and the designer wants to argue the
> point. Further the councils and other AHJ should select independent
> technical experts appropriate to the project, rather than have an on going
> contract with a local consultant.
>
> The development court has apparently ruled in various cases: expertise to
> the extent necessary to make an assessment, it doesn't require
> specialisation. That may be fine on the AHJ's side, but the industry is
> always complaining about how long it takes to get approval.
>
> My view is that it is the industries own fault. The builders and building
> designers could simply choose a private certifier with the appropriate
> specialisation, there is no need to go through council for building rules,
> when seeking development approval they simply advise council who the private
> certifier is. Once appointed they cannot change the certifier.
>
> More importantly they could get engineering done before seeking development
> approval, that way they would avoid the delay when a request for engineering
> is issued. If the work is of a simple nature then the engineer can act as
> independent technical expert and simply certify the structure. If the work
> is of a more complex nature, then the engineer acts as designer. To save
> time the design engineer can then seek another engineer to act as
> independent technical expert. There then should be two sets of calculations,
> but only the independent technical expert's certificate needs to be
> submitted for approval: the AHJ accepts that on good faith. The benefit is
> that the two independent engineers can be selected on basis of experience
> and specialisation. Calculations for the project can be minimised whilst a
> wealth of calculations are produced for an industry.
>
> The requirement for independence doesn't allow a senior engineer in the same
> company to act as technical expert; they have to find an external
> consultant. But there are exceptions for very specialised areas, but even
> then may still impose external assessment to the extent possible.
>
> Older engineers close to retirement can benefit. For example permissible
> stress codes are now obsolete, we only have limit state design. Building
> surveyors will reject calculations in permissible stress format, but the
> design engineer can get an independent technical expert to certify the
> design after checking to the limit states codes. If non-compliant the
> design-engineer can go away find design-solution using permissible stress,
> then get it checked for compliance with limit state.
>
> Whilst people complain about slowness of getting approval, it is the way
> most people operate within the system which is inefficient not entirely the
> system itself.
>
> Though licensing/registration of the engineers acting as independent
> technical experts would seem a beneficial addition: to improve consistency
> in what gets approved.
>
>
> Well that's not exactly brief. Hope it helps anyway.
>
>
>
> Some useful links:
>
>
>
> Planning Department:
>
> http://www.planning.sa.gov.au/
>
>
> The advisory notices:
>
> http://www.planning.sa.gov.au/index.cfm?objectId=D2206794-96B8-CC2B-6A72A074
> 741455CB
>
>
>
> The development Act:
>
> http://www.legislation.sa.gov.au/LZ/C/A/DEVELOPMENT%20ACT%201993.aspx
>
>
> The development Regulations:
>
> http://www.legislation.sa.gov.au/LZ/C/R/DEVELOPMENT%20REGULATIONS%201993.asp
> x
>
>
> Roof Truss Issues:
>
> http://www.planning.sa.gov.au/go/building/latest-building-policy-news/roof-t
> russes-ministerial-taskforce
>
> Faulty Trusses:
>
> http://www.planning.sa.gov.au/go/roof-check
>
> Simplified Wind Speed Maps:
>
> http://www.planning.sa.gov.au/go/building/technical-information/maps/design-
> wind-speeds/wind-speed-maps
>
>
>
> National Professional Engineers Register (NPER):
>
> http://www.engineersaustralia.org.au/nerb/
>
>
>
> 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:
> *
> * 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
> ******* ****** ****** ****** ******* ****** ****** ********
>
>

Fwd: Utility Poles for Electric Power Distribution

I want to add another site:

http://www.usda.gov/rus/electric/bulletins.htm

Regards,

Nam Trung, PECC3,

HCMC, Vietnam

From: David Topete [mailto:d.topete73@gmail.com]
Sent: Monday, June 02, 2008 11:59 AM
To: seaint@seaint.org
Subject: Re: Utility Poles for Electric Power Distribution

The Structural engineer employed by the electrical utility.

2008/6/1 milo zabala <milozabala@yahoo.com>:

Since we are on this subject:

Would someone clarify who is responsible for the design of utility
poles used in electric power distribution? Civil/Structural or
Electrical Engr?

thks,
M Zabala

----- Original Message ----
From: Harold Sprague <spraguehope@hotmail.com>
To: seaint@seaint.org
Sent: Friday, May 30, 2008 10:35:13 AM
Subject: RE: Power Plants

That is a lot of information to obtain. Good starting points:

Institute of Electrical and Electronics Engineers:
http://www.ieee.org/portal/site
They develop the standards like the IEEE 693

American Public Power Plant Association:
http://www.appanet.org/

Electric Power Research Institute:
http://my.epri.com/portal/server.pt

For some of the information you requested, you will have to go to the vendors.

Regards,
Harold Sprague

________________________________

Date: Fri, 30 May 2008 10:09:40 -0700
From: gmse4603@gmail.com
To: seaint@seaint.org
Subject: Power Plants

Anyone know where there is a good online summary of things involving
powerplants, substations and the like.

I'm currently interested in getting info related to High-voltage cable
weights, bend radii, clamping devices, connectors/splice, isolators
(for seismic) etc...

tia,
-gm

________________________________

E-mail for the greater good. Join the i'm Initiative from Microsoft.

--
David Topete, SE

________________________________

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6/1/2008 5:28 PM

RE: South Australia practices

Bill,

In South Australia development approval comprises of two parts:

1) Provisional Development Plan consent
2) Provisional building Rules consent

Only the local councils (AHJ) can grant development approval, and only once
the two consents have been granted. The assessment of building rules is
usually by building surveyors, a few are architects and a few are engineers,
most are not.

As I understand it, in the past people could simply go to local council and
ask what was required and they would be told what to do. Not sure how far
back that was, but the current development act was introduced in 1993, and I
believe the prior act required submission of structural calculations. When
it was introduced private certifiers were also introduced, and many councils
now send applications out to private certifiers for assessment: building
departments have shrunk in size. Private certifiers are registered building
surveyors, and I believe they have to also be either architects or
engineers. Private certifiers can only grant approval for building rules,
and building permit is not issued until get full development approval.

The building surveyor is not permitted to recommend design-solutions, they
have to remain independent. I believe at some point in the past a few
councils were sued because of faulty footings on reactive clay soils:
council is always there, other parties aren't.

What it means is if something is undersized the building surveyor cannot say
what size will be approved: they can only reiterate the requirements of the
building rules.

Also the development regulations require that the structural provisions of
the building code of Australia (BCA) are assessed by an independent
technical expert. At present however the definition of such is simply a
person with a 4 year B.Eng in Civil Engineering and a few years of
experience: it doesn't require registration on the national professional
engineers register (NPER). If the building surveyor is an engineer then they
can assess the structural provisions. Most building surveyors are not
engineers so most councils send development applications out to private
consulting engineers for structural assessment. These consultants usually
request the submission of engineering calculations. That is not really the
intent of the act.

A building surveyor is permitted to accept in good faith a certificate from
an independent technical expert, and is also required to seek such
certificates if aspects of a development proposal are beyond their scope of
competence.

So sometimes instead of asking for engineering calculations they will simply
ask for a certificate of an independent technical expert. If an engineer
specialises in a particular area of practice then they can simply look at
something and say it is similar to a 100 other projects, and certify it. But
if the proposal is deficient they cannot advise or specify the requirements
to make it acceptable.

In which case they remove the reference to independent technical expert and
issue a certificate of structural adequacy with conditions. If it is simple
the engineer representing the AHJ will accept that without calculations, if
not simple then may request the calculations or other evidence to support.
{On the other hand the AHJ's request for a certificate makes it sound like a
simple exercise to the owner of the building.}

The building code of Australia (BCA) requires evidence-of-suitability, but
indicates that a certificate from a suitably qualified person is adequate
evidence. (NPER is called up as one option of suitably qualified, but not
necessary)

To me it seems that in practice there are double standards. The building
surveyors do a lot of the assessment themselves without calculations or
other documentary evidence: access/egress requirements, fire rated
construction, timber framing and more. Not all of this is simple
prescriptive comparative checks, it requires some effort and justification.
They do not ask designers to submit calculations for such things: the
building surveyor does what ever is required.

But structural even if building surveyor is an engineer and able to make the
assessment, they still want some calculations submitted.

The issue I have with that is: in many cases it is a waste of time and
paper, and waste of space to store the paper, especially for those
situations where the calculations are just tedious repetition to satisfy a
paper trail. Further more the requirement is technical check: does the
proposal comply with the code. According to some reports, often only an
arithmetical check is carried out: relevance and deficiencies in the
calculations not understood or recognised.

If the technical experts were selected correctly, then they would have
appropriate tools to review the proposals in the shortest time frame
possible. Given such tools it is a waste of time to decipher hand written
scribble, when can check the specification directly.

The intent of the 1993 development act was to speed up approval. My view is
that the designer only needs to submit their calculations, when the checker
considers there is a non-compliance, and the designer wants to argue the
point. Further the councils and other AHJ should select independent
technical experts appropriate to the project, rather than have an on going
contract with a local consultant.

The development court has apparently ruled in various cases: expertise to
the extent necessary to make an assessment, it doesn't require
specialisation. That may be fine on the AHJ's side, but the industry is
always complaining about how long it takes to get approval.

My view is that it is the industries own fault. The builders and building
designers could simply choose a private certifier with the appropriate
specialisation, there is no need to go through council for building rules,
when seeking development approval they simply advise council who the private
certifier is. Once appointed they cannot change the certifier.

More importantly they could get engineering done before seeking development
approval, that way they would avoid the delay when a request for engineering
is issued. If the work is of a simple nature then the engineer can act as
independent technical expert and simply certify the structure. If the work
is of a more complex nature, then the engineer acts as designer. To save
time the design engineer can then seek another engineer to act as
independent technical expert. There then should be two sets of calculations,
but only the independent technical expert's certificate needs to be
submitted for approval: the AHJ accepts that on good faith. The benefit is
that the two independent engineers can be selected on basis of experience
and specialisation. Calculations for the project can be minimised whilst a
wealth of calculations are produced for an industry.

The requirement for independence doesn't allow a senior engineer in the same
company to act as technical expert; they have to find an external
consultant. But there are exceptions for very specialised areas, but even
then may still impose external assessment to the extent possible.

Older engineers close to retirement can benefit. For example permissible
stress codes are now obsolete, we only have limit state design. Building
surveyors will reject calculations in permissible stress format, but the
design engineer can get an independent technical expert to certify the
design after checking to the limit states codes. If non-compliant the
design-engineer can go away find design-solution using permissible stress,
then get it checked for compliance with limit state.

Whilst people complain about slowness of getting approval, it is the way
most people operate within the system which is inefficient not entirely the
system itself.

Though licensing/registration of the engineers acting as independent
technical experts would seem a beneficial addition: to improve consistency
in what gets approved.

Well that's not exactly brief. Hope it helps anyway.

Some useful links:

Planning Department:

http://www.planning.sa.gov.au/

The advisory notices:

http://www.planning.sa.gov.au/index.cfm?objectId=D2206794-96B8-CC2B-6A72A074
741455CB

The development Act:

http://www.legislation.sa.gov.au/LZ/C/A/DEVELOPMENT%20ACT%201993.aspx

The development Regulations:

http://www.legislation.sa.gov.au/LZ/C/R/DEVELOPMENT%20REGULATIONS%201993.asp
x

Roof Truss Issues:

http://www.planning.sa.gov.au/go/building/latest-building-policy-news/roof-t
russes-ministerial-taskforce

Faulty Trusses:

http://www.planning.sa.gov.au/go/roof-check

Simplified Wind Speed Maps:

http://www.planning.sa.gov.au/go/building/technical-information/maps/design-
wind-speeds/wind-speed-maps

National Professional Engineers Register (NPER):

http://www.engineersaustralia.org.au/nerb/

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

Thursday, August 21, 2008

Dowel Locations

I just done a ICF wall design with the boundary conditions at floor level and foundations as pinned. Because of Simply supported action the rebar calculated at mid point. Calculated rebar is given in full wall height without curtailment. While calculating dowel bars as per ACI Min requirement and by Shear friction. It is Less than Minimum requirement. Is it Dowel bar locations should match with Main rebar location everywhere. Can anyone suggest me in this context.

Regards

ARUNKUMAR C

RE: Wind load design for Photovoltaic panel installations

Dennis,

One possibility. The roof truss exists already, therefore it is meant to be code compliant.

Therefore:

1) Analyse truss as is. (Gives estimate of minimum available resistance)

2) Analyse truss with the additional loading of the solar panel

3) Difference between two is the required reinforcement

4) Find a design-solution to provide the reinforcement

5) If don’t believe existing truss is up to current code requirements provide some additional resistance

6) Experiment with the associated parameters to determine limitations of the design-solution

7) On next project assess if design-solution suitable without need to re-calculate. If not suitable then find new design-solution

8) Once have design –solution determine the cost of implementation

9) Then the cost of recovery on the solar panels can then be reassessed by the owners and suppliers.

10) The industry probably won’t be happy about the cost of strengthening existing, and will seek an official compromise by creating an industry association and producing a prescriptive specification approved by the AHJ. The problem will then only remain for a few irregular installations.

Regards

Conrad Harrison

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

mailto:sch.tectonic@bigpond.com

Adelaide

South Australia

Re: Rho, Rho, Rho your boat (foundation)

Bill,

You are right. Sorry I read it too fast.

Jules

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

From: William.Sherman@CH2M.com

To: seaint@seaint.org

Sent: Thursday, August 21, 2008 9:16 AM

Subject: RE: Rho, Rho, Rho your boat (foundation)

I'm not sure your interpretation is correct. I agree that 12.3.4.2 seems contradictory - I think that it should state "except as defined in 12.3.4.1". I believe the intent is that, for example, drift and P-delta effects are calculated without the rho factor even in Seismic Design Categories D through F.

Bill Sherman

CH2M HILL / DEN

720-286-2792

From: Jules [mailto:JulesG@socal.rr.com]
Sent: Wednesday, August 20, 2008 10:11 AM
To: seaint@seaint.org
Subject: Re: Rho, Rho, Rho your boat (foundation)

I think the wording of the ASCE Section 12.3.4.1 Is not very good. The intent is that ALL conditions should be met for rho =1. Otherwise Section 12.3.4.2 would be contradictory.

Jules

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

From: Yousefi, Ben

To: seaint@seaint.org

Sent: Tuesday, August 19, 2008 9:36 AM

Subject: RE: Rho, Rho, Rho your boat (foundation)

Section 12.3.4.1 of ASCE 7 specifies the conditions where Rho can be assumed to equal 1.0. Foundation is not one of them.

Ben Yousefi, SE, CBO

Chief Building Official

City of Mountain View, CA

(650) 526-7007

ben.yousefi@mountainview.gov

From: Garner, Robert [mailto:rgarner@moffattnichol.com]
Sent: Tuesday, August 19, 2008 9:22 AM
To: seaint@seaint.org
Subject: Rho, Rho, Rho your boat (foundation)

I'm designing a steel framed structure in Seismic Category D. For the steel framing, Rho will be 1.3. For the foundation (a concrete mat foundation), we are using a Rho of 1.0 - our reasoning being that the purpose of Rho is to assure that no single seismic force resisting element above the foundation (the building frames) will likely fail in an earthquake. Nowhere in the Codes can I find a statement that Rho is to be applied to the foundation. Can anyone challenge me on this with a Code quote or logical argument?

Thanks for any help you can offer.

Bob Garner, S.E.

R. Garner

Moffatt & Nichol

Tel.: (619) 220-6050

Fax.: (619) 220-6055

e-mail: rgarner@moffattnichol.com

Simpson 3x3 washers for sill plate anchors

2305.3.11 of the 2007 CBC requires 3x3x.229" thick washers. Oddly Simpson does not make this for a 3/4" anchor bolt. They do make a 2.75x2.75x5/16" for 3/4 anchors, but this does not meet the code requirements. They do make a 3"x3"x1/4 for 1/2" and 5/8" dia anchors. So if we want to use 3/4" anchor bolts the washers need to be fabricated unless someone else makes these.

Jeff

Re: Is this news?

Well, the collapse of WTC 7 remained a mystery as to how it completely collapsed without having a jumbo jet crash into it... It only took 7 years... No, it's not news...

On Thu, Aug 21, 2008 at 12:08 PM, Michel Blangy <mblangy@satco-inc.com> wrote:

http://www.breitbart.com/article.php?id=D92MQLDG0&show_article=1

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David Topete, SE

Is this news?

http://www.breitbart.com/article.php?id=D92MQLDG0&show_article=1

RE: Rho, Rho, Rho your boat (foundation)

25% off on foundation overturning*

========================

* On select structures. See ASCE 12.13.4

From: Teo, KP [mailto:KP_Teo@fwhou.fwc.com]
Sent: Thursday, August 21, 2008 3:52 AM
To: seaint@seaint.org
Subject: RE: Rho, Rho, Rho your boat (foundation)

If I remember correctly, foundation under the conditions where Rho can be taken as 1.0 is included in California Building Code 1998, which is based on UBC 1997.

It may not be applicable to the code that you're designing to.

From: Jules [mailto:JulesG@socal.rr.com]
Sent: Wednesday, August 20, 2008 11:11 AM
To: seaint@seaint.org
Subject: Re: Rho, Rho, Rho your boat (foundation)

I think the wording of the ASCE Section 12.3.4.1 Is not very good. The intent is that ALL conditions should be met for rho =1. Otherwise Section 12.3.4.2 would be contradictory.

Jules

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

From: Yousefi, Ben

To: seaint@seaint.org

Sent: Tuesday, August 19, 2008 9:36 AM

Subject: RE: Rho, Rho, Rho your boat (foundation)

Section 12.3.4.1 of ASCE 7 specifies the conditions where Rho can be assumed to equal 1.0. Foundation is not one of them.

Ben Yousefi, SE, CBO

Chief Building Official

City of Mountain View, CA

(650) 526-7007

ben.yousefi@mountainview.gov

From: Garner, Robert [mailto:rgarner@moffattnichol.com]
Sent: Tuesday, August 19, 2008 9:22 AM
To: seaint@seaint.org
Subject: Rho, Rho, Rho your boat (foundation)

I'm designing a steel framed structure in Seismic Category D. For the steel framing, Rho will be 1.3. For the foundation (a concrete mat foundation), we are using a Rho of 1.0 - our reasoning being that the purpose of Rho is to assure that no single seismic force resisting element above the foundation (the building frames) will likely fail in an earthquake. Nowhere in the Codes can I find a statement that Rho is to be applied to the foundation. Can anyone challenge me on this with a Code quote or logical argument?

Thanks for any help you can offer.

Bob Garner, S.E.

R. Garner

Moffatt & Nichol

Tel.: (619) 220-6050

Fax.: (619) 220-6055

e-mail: rgarner@moffattnichol.com

--------------------------------------------------------------------------------------------------------------------------------------
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Effective July 7, 2008, Foster Wheeler USA Corporation will have a new address:
585 N. Dairy Ashford
Houston, TX 77079
713-929-5000
Please make note of the new information for your records.

RE: Rho, Rho, Rho your boat (foundation)

I'm not sure your interpretation is correct. I agree that 12.3.4.2 seems contradictory - I think that it should state "except as defined in 12.3.4.1". I believe the intent is that, for example, drift and P-delta effects are calculated without the rho factor even in Seismic Design Categories D through F.

Bill Sherman

CH2M HILL / DEN

720-286-2792

From: Jules [mailto:JulesG@socal.rr.com]
Sent: Wednesday, August 20, 2008 10:11 AM
To: seaint@seaint.org
Subject: Re: Rho, Rho, Rho your boat (foundation)

I think the wording of the ASCE Section 12.3.4.1 Is not very good. The intent is that ALL conditions should be met for rho =1. Otherwise Section 12.3.4.2 would be contradictory.

Jules

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

From: Yousefi, Ben

To: seaint@seaint.org

Sent: Tuesday, August 19, 2008 9:36 AM

Subject: RE: Rho, Rho, Rho your boat (foundation)

Section 12.3.4.1 of ASCE 7 specifies the conditions where Rho can be assumed to equal 1.0. Foundation is not one of them.

Ben Yousefi, SE, CBO

Chief Building Official

City of Mountain View, CA

(650) 526-7007

ben.yousefi@mountainview.gov

From: Garner, Robert [mailto:rgarner@moffattnichol.com]
Sent: Tuesday, August 19, 2008 9:22 AM
To: seaint@seaint.org
Subject: Rho, Rho, Rho your boat (foundation)

I'm designing a steel framed structure in Seismic Category D. For the steel framing, Rho will be 1.3. For the foundation (a concrete mat foundation), we are using a Rho of 1.0 - our reasoning being that the purpose of Rho is to assure that no single seismic force resisting element above the foundation (the building frames) will likely fail in an earthquake. Nowhere in the Codes can I find a statement that Rho is to be applied to the foundation. Can anyone challenge me on this with a Code quote or logical argument?

Thanks for any help you can offer.

Bob Garner, S.E.

R. Garner

Moffatt & Nichol

Tel.: (619) 220-6050

Fax.: (619) 220-6055

e-mail: rgarner@moffattnichol.com

RE: South Australia practices

Conrad,

I am interested in your statement that "we require an independent technical check before approval can be granted". How is this requirement defined - local building code, professional engineer practice requirements, or other? Can you provide sample wording of the requirement?

Bill Sherman
CH2M HILL / DEN
720-286-2792

> -----Original Message-----
> From: Conrad Harrison [mailto:sch.tectonic@bigpond.com]
> Sent: Wednesday, August 20, 2008 9:22 PM
> To: seaint@seaint.org
> Subject: RE: Photovoltaic Panels & Manufactured Metal Plated
> Roof Truss - Addendum
>
> Dennis,
>
> Also here I believe there is still an on going debate that
> the output from the truss manufacturer's software is
> inadequate. I'm not sure about other states but in South
> Australia, we require an independent technical check before
> approval can be granted. Certifying engineers cannot sensibly
> do that based on the information output from the software;
> further more there are some doubts that the software can
> actually design the joints properly...
>
> Regards
> Conrad Harrison
> B.Tech (mfg & mech), MIIE, gradTIEAust
> mailto:sch.tectonic@bigpond.com
> Adelaide
> South Australia

Re: Wind load design for Photovoltaic panel installations

Agreed. A solar panel weighing 3 psf, standing off 6" from the roof surface having a pitch of 8:12, essentially takes the place of the 16 psf roof live load. Once the panel is removed for a reroof, then the roof structure should still be adequate for a 16 psf live load, with a 7-day load duration factor (per NDS for wood) of 1.25.

Yes, if the panel is inclined near vertical to a "flat" roof surface, then, yes, the roof still needs to support the panel weights in addition to the standard roof live load.

I may have lost track of Dennis' original post, but it seems to me (at least in the project I am looking at) that the roof members see no difference in their initial design.

On Wed, Aug 20, 2008 at 8:57 PM, Conrad Harrison <sch.tectonic@bigpond.com> wrote:

David,

I don't believe the live load becomes zero. My understanding is that the live loading allowance is for construction and maintenance. During Installation of the solar panels, that loading still needs to be allowed for on the house roof. However, if the solar panels are offset from the roof surface, then no additional live loading would be expected on the top of the solar panels themselves. There after no live loading can be applied to the roof below the panels, but that would be dependent on the angle of the panels relative to the roof slope. If the house roof is relatively flat and the panels are near vertical (relatively speaking), then can still access roof behind the panel.

But no one should be standing or stacking materials on the solar panel. From another perspective the panels could be considered a brittle roof structure. So if they are laid hard against the existing roof structure, and possible to walk from ordinary roof and accidentally tread on panels: then want the roof below to provide adequate support.

So I would say there is no additional live load applied to the panel, but also no live load removed from the roof.

Regards

Conrad Harrison

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

mailto:sch.tectonic@bigpond.com

Adelaide

South Australia

--
David Topete, SE

RE: Rho, Rho, Rho your boat (foundation)

If I remember correctly, foundation under the conditions where Rho can be taken as 1.0 is included in California Building Code 1998, which is based on UBC 1997.

It may not be applicable to the code that you're designing to.

From: Jules [mailto:JulesG@socal.rr.com]
Sent: Wednesday, August 20, 2008 11:11 AM
To: seaint@seaint.org
Subject: Re: Rho, Rho, Rho your boat (foundation)

I think the wording of the ASCE Section 12.3.4.1 Is not very good. The intent is that ALL conditions should be met for rho =1. Otherwise Section 12.3.4.2 would be contradictory.

Jules

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

From: Yousefi, Ben

To: seaint@seaint.org

Sent: Tuesday, August 19, 2008 9:36 AM

Subject: RE: Rho, Rho, Rho your boat (foundation)

Section 12.3.4.1 of ASCE 7 specifies the conditions where Rho can be assumed to equal 1.0. Foundation is not one of them.

Ben Yousefi, SE, CBO

Chief Building Official

City of Mountain View, CA

(650) 526-7007

ben.yousefi@mountainview.gov

From: Garner, Robert [mailto:rgarner@moffattnichol.com]
Sent: Tuesday, August 19, 2008 9:22 AM
To: seaint@seaint.org
Subject: Rho, Rho, Rho your boat (foundation)

I'm designing a steel framed structure in Seismic Category D. For the steel framing, Rho will be 1.3. For the foundation (a concrete mat foundation), we are using a Rho of 1.0 - our reasoning being that the purpose of Rho is to assure that no single seismic force resisting element above the foundation (the building frames) will likely fail in an earthquake. Nowhere in the Codes can I find a statement that Rho is to be applied to the foundation. Can anyone challenge me on this with a Code quote or logical argument?

Thanks for any help you can offer.

Bob Garner, S.E.

R. Garner

Moffatt & Nichol

Tel.: (619) 220-6050

Fax.: (619) 220-6055

e-mail: rgarner@moffattnichol.com