Structural Engineering: 2007-07-15

Saturday, July 21, 2007

Re: Eccentric Shear on Screws

> Brad,
Have you tried the cold formed steel framing manual (not sure of the
title) available from AISI. It is supposed to have information on
connections, including screws. I know the Canadian version which came
out prior to the AISI one has a lot on screws and bolts in light gauge
steel.
Gary Hodgson
>
>
>
> */Brad Cameron <bsc@keymark.com>/* wrote:
>
> Hello from a long time Seaint "digest mode" lurker! I have benefited
> many times from the comments I see on this forum.
>
> I often design connections using screws in cold formed steel
> connections
> to resist eccentric shear. Little bitty #10 screws into 33 mil (20
> gage) sheet steel. Sometimes the steel is as thick as 54 mil (16
> gage).
>
> The easy way out is to design this connection using the elastic
> method.
> But how conservative is this for screws?
>
> The ultimate strength analysis method for bolts assumes a
> nonlinear load
> deformation relationship. The equation that governs this relationship
> in the AISC Manual is:
>
> R = Rult ( 1 - e ^ (-10 DEL) ) ^ 0.55
>
> Sorry if the formatting is hard to read. I learned on Salmon and
> Johnston's "Steel Structures", 2nd edition. Oops, now you might know
> how much of an old timer I am. In this book they state that the
> coefficients "10" and "0.55" in this equation are experimentally
> determined, resulting in a maximum delta at failure of about 0.35
> inches, using 3/4" A325 bolts. On page 135. I think this means that
> the bolt is assumed to drag through the steel for almost 3/8 inch,
> allowing the forces to redistribute amongst the fasteners.
>
> Given this, I wonder whether the equations as stated in the AISC
> manual
> for ultimate strength analysis are applicable to the dinky little
> screws
> I sometimes use. No way will I get 0.35 inches of movement out of
> a #10
> screw before it breaks or otherwise just gives up.
>
> Back on page 134, they say "Actually the concept of instantaneous
> center
> is identical to the elastic (vector) method if the resistance Ri is
> proportional to the deformation (i.e. stress is proportional to
> strain)." Makes me wonder what the load deformation curve of a #10
> screw
> looks like in cold formed steel.
>
> Anybody got any insights or suggestions - perhaps a way to derive
> coefficients appropriate for screws?
>
> Thank you in advance for your help!
> Brad Cameron
> Keymark Engineering
>
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Friday, July 20, 2007

Re: Design preference for non-bearing wall connectors

I would suggest shot pins if the connection of the track to the WF is flush. If there is supposed to be fireproofing on the WF, you usually end up shot pinning zee strips to the WF, then applying the track to the zee furing with screws and filling the space between the track and WF with fireproofing.

Paul.

Phoenix

On 7/20/07, Donald Bruckman <bruckmandesign@verizon.net> wrote:

Thanks for the response. I was surprised that he would suggest screws, and on top of that, declare it "better". Given the difficulty in the QC of screw installation upside down 18' feet in the air, an argument might be made that it is even less "better".

From: Jim Wilson [mailto: wilsonengineers@yahoo.com]
Sent: Friday, July 20, 2007 10:42 AM
To: seaint@seaint.org
Subject: RE: Design preference for non-bearing wall connectors

I agree. Pins are far easier to install compared to overhead drilling.

The only problems I've encountered with pins into steel is with higher strength steels. But that was worked out by choosing the correct gun and pin for the application.

Jim Wilson, PE

Stroudsburg, PA

David Topete < dtopete@gfdseng.com> wrote:

My quick opinion, FWIW...

A #10 screw into the flange of a W24 seems like a difficult task with the
thinnest flange thickness being 1/2". I would say the powder pins are the
way to go.

David A. Topete, SE

-----Original Message-----
From: Donald Bruckman [mailto: bruckmandesign@verizon.net]
Sent: Friday, July 20, 2007 8:56 AM
To: seaint@seaint.org
Subject: Design preference for non-bearing wall connectors

I have a non-bearing metal stud wall that is to be attached to the underside
of a W24. The detail was missed by the SE on the permit set and so I
sketched up a detail of a slip track with shot pins into the bottom flange
to connect the track. The SE revised the detail to self drilling screws,
claiming it was a "better" connection. (I'm not quite sure which element
became "better"), but...nevertheless, it begs this question:

Is there any consensus here about whether either version is a "better" or
"worse" version of this detail? Does the shot pin mess with the flange
integrity in any way that could be considered more deleterious than an S-D
screw? (The exact detail was 6" metal stud x 18' high, GWB both sides. I
guessed 145 shots @ 16"oc, his came back #10 SD screws at 8"oc.).

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PCA Mats Software

I have used ADAPT-MAT on a few of my foundations projects and found it to be quite flexible. Compared to my experience using SAFE, it is much easier to use and can handle complicated geometries better than SAFE. I also have their post tensioning design module that works with ADAPT-MAT.

Ahmad

From: "Gerard Madden, SE" <gmse4603@gmail.com>

To: seaint@seaint.org

Subject: Re: PCA Mats Software

------=_Part_125491_32176844.1184869029402

Content-Type: text/plain; charset=WINDOWS-1252; format=flowed

Content-Transfer-Encoding: quoted-printable

Content-Disposition: inline

Both are good programs like you said.

SAFE is more powerful for the reasons Jim mentioned.

One disappointment with SAFE, was when I was purchasing it about 4 years

ago, I was told that the next version would have PT Floor design

capabilities. Well, 4 years later, that's still not a feature.

But it's a good program none-the-less

-g

To help you stay safe and secure online, we've developed the all new Yahoo! Security Centre.

RE: Design preference for non-bearing wall connectors

Thanks for the response. I was surprised that he would suggest screws, and on top of that, declare it “better”. Given the difficulty in the QC of screw installation upside down 18’ feet in the air, an argument might be made that it is even less “better”.

From: Jim Wilson [mailto:wilsonengineers@yahoo.com]
Sent: Friday, July 20, 2007 10:42 AM
To: seaint@seaint.org
Subject: RE: Design preference for non-bearing wall connectors

I agree. Pins are far easier to install compared to overhead drilling.

The only problems I've encountered with pins into steel is with higher strength steels. But that was worked out by choosing the correct gun and pin for the application.

Jim Wilson, PE

Stroudsburg, PA

David Topete <dtopete@gfdseng.com> wrote:

My quick opinion, FWIW...

A #10 screw into the flange of a W24 seems like a difficult task with the
thinnest flange thickness being 1/2". I would say the powder pins are the
way to go.

David A. Topete, SE

-----Original Message-----
From: Donald Bruckman [mailto:bruckmandesign@verizon.net]
Sent: Friday, July 20, 2007 8:56 AM
To: seaint@seaint.org
Subject: Design preference for non-bearing wall connectors

I have a non-bearing metal stud wall that is to be attached to the underside
of a W24. The detail was missed by the SE on the permit set and so I
sketched up a detail of a slip track with shot pins into the bottom flange
to connect the track. The SE revised the detail to self drilling screws,
claiming it was a "better" connection. (I'm not quite sure which element
became "better"), but...nevertheless, it begs this question:

Is there any consensus here about whether either version is a "better" or
"worse" version of this detail? Does the shot pin mess with the flange
integrity in any way that could be considered more deleterious than an S-D
screw? (The exact detail was 6" metal stud x 18' high, GWB both sides. I
guessed 145 shots @ 16"oc, his came back #10 SD screws at 8"oc.).

******* ****** ******* ******** ******* ******* ******* ***
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RE: Design preference for non-bearing wall connectors

I agree. Pins are far easier to install compared to overhead drilling.

The only problems I've encountered with pins into steel is with higher strength steels. But that was worked out by choosing the correct gun and pin for the application.

Jim Wilson, PE

Stroudsburg, PA

David Topete <dtopete@gfdseng.com> wrote:

My quick opinion, FWIW...

A #10 screw into the flange of a W24 seems like a difficult task with the
thinnest flange thickness being 1/2". I would say the powder pins are the
way to go.

David A. Topete, SE

-----Original Message-----
From: Donald Bruckman [mailto:bruckmandesign@verizon.net]
Sent: Friday, July 20, 2007 8:56 AM
To: seaint@seaint.org
Subject: Design preference for non-bearing wall connectors

I have a non-bearing metal stud wall that is to be attached to the underside
of a W24. The detail was missed by the SE on the permit set and so I
sketched up a detail of a slip track with shot pins into the bottom flange
to connect the track. The SE revised the detail to self drilling screws,
claiming it was a "better" connection. (I'm not quite sure which element
became "better"), but...nevertheless, it begs this question:

Is there any consensus here about whether either version is a "better" or
"worse" version of this detail? Does the shot pin mess with the flange
integrity in any way that could be considered more deleterious than an S-D
screw? (The exact detail was 6" metal stud x 18' high, GWB both sides. I
guessed 145 shots @ 16"oc, his came back #10 SD screws at 8"oc.).

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

******* ****** ******* ******** ******* ******* ******* ***
* 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
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RE: Design preference for non-bearing wall connectors

I would agree...shot-pins are the way to go. That is essentially the
detail we use when attaching non-bearing metal stud walls to the
underside of steel beams.

Doug Mayer, SE
Structural Engineer

TaylorTeter
Partnership

7535 North Palm Ave., Suite 201
Fresno, CA 93711

(559) 437-0887 Ph.
(559) 438-7554 Fax
doug.mayer@taylorteter.com

-----Original Message-----
From: David Topete [mailto:dtopete@gfdseng.com]
Sent: Friday, July 20, 2007 9:03 AM
To: seaint@seaint.org
Subject: RE: Design preference for non-bearing wall connectors

My quick opinion, FWIW...

A #10 screw into the flange of a W24 seems like a difficult task with
the
thinnest flange thickness being 1/2". I would say the powder pins are
the
way to go.

David A. Topete, SE

-----Original Message-----
From: Donald Bruckman [mailto:bruckmandesign@verizon.net]
Sent: Friday, July 20, 2007 8:56 AM
To: seaint@seaint.org
Subject: Design preference for non-bearing wall connectors

I have a non-bearing metal stud wall that is to be attached to the
underside
of a W24. The detail was missed by the SE on the permit set and so I
sketched up a detail of a slip track with shot pins into the bottom
flange
to connect the track. The SE revised the detail to self drilling
screws,
claiming it was a "better" connection. (I'm not quite sure which
element
became "better"), but...nevertheless, it begs this question:

Is there any consensus here about whether either version is a "better"
or
"worse" version of this detail? Does the shot pin mess with the flange
integrity in any way that could be considered more deleterious than an
S-D
screw? (The exact detail was 6" metal stud x 18' high, GWB both sides.
I
guessed 145 shots @ 16"oc, his came back #10 SD screws at 8"oc.).

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

RE: Steel drag strut to masonry connection

I just went through this a few months ago. Please…my advice, negate all lateral force, “flat earth” it; deny it exists, and don’t design these bad boys.

OR,

1. Be sure to design a connection embedment detail that is a “thing” that can be delivered to the site and manhandled by the masons while they are building the wall. If the masons leave with a few A706 bars sticking out of the end, you are in for trouble. Inevitably you will have alignment issues because of space limitations. The masons need to be the guys responsible for the connection integrity, not the steel guys coming in behind them. I need to be able to mock the thing up in place and align it while the wall is going up and ascertain if I have access to weld, how the drag strut will seat, etc..

2. Okay, now, my biggest, and I mean BIGGEST complaint about engineering drawings. In a connection like this and in all areas where there’s a lot of engineering going on, you folks need to draw the rebar and the block and the steel to actual size. That includes masonry walls with accurate cells dims and #8 bars shown 1” wide, to scale, not just a “medium” or “wide” width line from the line style pull-down menu. You need to know what you are dealing with, or more succinctly, what my masons are dealing with. Clearances in masonry are a lot harder to achieve than the line on the drawing might indicate unless that line is drawn as wide as the bar you want to use. The radius of a bent bar needs to be shown in its real diameter. Stuff like that matters in the field. (Okay, off the soapbox).

From: David Topete [mailto:dtopete@gfdseng.com]
Sent: Thursday, July 19, 2007 11:29 AM
To: seaint@seaint.org
Subject: RE: Steel drag strut to masonry connection

Just be careful to check the connection for the combined effects of gravity and seismic. Working with an 8” masonry wall can be unbelievably maddening.

David A. Topete, SE

From: Jeff Hedman [mailto:jeff_h@lrpope.com]
Sent: Thursday, July 19, 2007 11:24 AM
To: seaint@seaint.org
Subject: RE: Steel drag strut to masonry connection

David,

Thanks for the input. It sounds like I am barking up the right tree.

Jeff Hedman , E.I.T.

L.R. Pope Engineers & Surveyors, Inc.

1240 East 100 South Suite # 15B

St. George, Utah 84790

Office: 435-628-1676

Fax: 435-628-1788

responsibility to retrofit existing structure during renovation

I am looking for some guidance and especially legal precedent for the responsibility and/or liability that an engineer may face when doing renovations and additions to existing structures.

In particular I am wondering how an engineer decides to what extent to require structural retrofitting of existing elements and systems that may be exposed during renovation under the following conditions:

the proposed renovations have little or no structural effect on the existing structural system.
the structural element/system in question has been exposed during renovation (eg. Removal of ceiling and wallboard).
the existing structure meets the code it was built under and is may not be considered immanently dangerous.
the existing structure clearly does not meet current code (eg. Trusses toe-nailed to top plate in high wind area).
the code exempts the existing structure from compliance with the current structural code because renovations are under a certain threshold.
minor structural modifications could greatly increase the safety of the building even if it doesn’t meet current code.

Thanks in advance.

Christopher Banbury, PE

President

Ark Engineering, Inc.

PO Box 10129, Brooksville, FL 34603

22 North Broad ST, Brooksville, FL 34601

Phone: (352) 754-2424

Fax: (352) 754-2412

www.arkengineering.net

Re: Residential Engineering Review/Coordination Process

All of this kind of makes me glad I practice in Califonia.

Ralph

In a message dated 7/20/07 9:14:43 AM, cbanbury@arkengineering.net writes:

The situation was very similar in Florida until the adoption of the 2001 and 2004 FBC and some rule changes by the engineering board.
Probably the best thing the board did was to explicitly require communication between the truss engineer and the engineer of record. The state had previously adopted TPI-1 Chapter 2 but the truss engineer is typically contracted with the owner/contractor and is not a sub-consultant of the engineer of record. Engineers were having a hard time controlling the document flow to and from the truss engineer.
You can review the florida laws and rules at www.fbpe.org.

We still have some similar issues as you mention but the gap is closing in my opinion. For example, even though residential prescriptive design is technically still allowed without an engineer, most building officials here are very critical of plans submitted without an engineer's certification.

There are very few engineers now doing wind or lateral only engineering even though it is technically permitted in the code as long as the contractor provides the remaining structural and non-structural certifications. The building officials make this very difficult and for good reason I think.

The building official has the authority to accept the seal of the engineer as proof of code compliance without further review. However, only the smallest undermanned jurisdictions do this in my experience. I too appreciate the scrutiny of the AHJ.

The owner that wants the engineer to conduct construction observation for residential is a rare creature.

With regard to the IRC, the Florida flavor of the IBC/IRC permits a combination of IBC-style engineered design and IRC-style prescriptive design as long as the engineered design is compatible and consistent with the prescriptive "design". Engineered design is usually required here since much of florida is above most of the wind speed thresholds in the Florida IRC prescriptive documents and most houses exceed the size/span/height/configuration limitations of the Florida IRC.

The best thing that I have done in the past few years is to require written contracts for all jobs. The florida building code, statutes, and board rules give a wide berth to contractual arrangements between the engineer and owner. You will find that the best way to control your liability, responsibility, and project coordination requirements is to put it into the agreement. Owners/contractors/building officials may not appreciate the rules that you must operate under but they and the courts understand written contracts and these often trump contrary practices and board "guidelines" to the contrary.

Christopher Banbury, PE
President

Ark Engineering, Inc.
PO Box 10129, Brooksville, FL 34603
22 North Broad ST, Brooksville, FL 34601
Phone: (352) 754-2424
Fax: (352) 754-2412
www.arkengineering.net

**************************************
Get a sneak peek of the all-new AOL at http://discover.aol.com/memed/aolcom30tour

RE: Project Management Software

I’ve used MS Project up to Primavera and, unless you are getting into acute coordination of lots of entities, and by that I mean managing both money and resources as well as just critical path stuff, stick with MS Project.

From: Bill Polhemus [mailto:bill@polhemus.cc]
Sent: Thursday, July 19, 2007 11:10 AM
To: seaint@seaint.org
Subject: Re: Project Management Software

Mark Deardorff wrote:

My company does projects with planning horizons from a few days to a few months. Is there any software out there that would make sense for quick projects?

MS Project is probably the "easiest."

However, if you don't want to spend the money--especially if you want several folks in your organization to have access to the project scheduling files--you might want to consider this:

http://www.openworkbench.org/

RE: Design preference for non-bearing wall connectors

My quick opinion, FWIW...

A #10 screw into the flange of a W24 seems like a difficult task with the
thinnest flange thickness being 1/2". I would say the powder pins are the
way to go.

David A. Topete, SE

I have a non-bearing metal stud wall that is to be attached to the underside
of a W24. The detail was missed by the SE on the permit set and so I
sketched up a detail of a slip track with shot pins into the bottom flange
to connect the track. The SE revised the detail to self drilling screws,
claiming it was a "better" connection. (I'm not quite sure which element
became "better"), but...nevertheless, it begs this question:

Is there any consensus here about whether either version is a "better" or
"worse" version of this detail? Does the shot pin mess with the flange
integrity in any way that could be considered more deleterious than an S-D
screw? (The exact detail was 6" metal stud x 18' high, GWB both sides. I
guessed 145 shots @ 16"oc, his came back #10 SD screws at 8"oc.).

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

RE: LENTON Mason Lock

My experience with any of these "cost saving" methods of splicing is that
they aren't.

-----Original Message-----
From: Martin Li [mailto:mli@tb-engr.com]
Sent: Friday, July 20, 2007 7:18 AM
To: seaint@seaint.org
Subject: RE: LENTON Mason Lock

Does anyone have experiences with LENTON Mason Lock?
http://www.erico.com/public/library/Concrete/LT0958.pdf

Regards,

Martin

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

Design preference for non-bearing wall connectors

I have a non-bearing metal stud wall that is to be attached to the underside
of a W24. The detail was missed by the SE on the permit set and so I
sketched up a detail of a slip track with shot pins into the bottom flange
to connect the track. The SE revised the detail to self drilling screws,
claiming it was a "better" connection. (I'm not quite sure which element
became "better"), but...nevertheless, it begs this question:

Is there any consensus here about whether either version is a "better" or
"worse" version of this detail? Does the shot pin mess with the flange
integrity in any way that could be considered more deleterious than an S-D
screw? (The exact detail was 6" metal stud x 18' high, GWB both sides. I
guessed 145 shots @ 16"oc, his came back #10 SD screws at 8"oc.).

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

Re: Eccentric Shear on Screws

Brad,

Is there an actual gap between the loaded plies? I <think> that you would ignore bending if there is a solid shim in place. In that case, you could consider pull-over of the head in the outer ply per AISI specs if there is a possibility for some head rotation.

Another avenue to check is through Hilti's technical information. If you can access section 4.1.2.8 Bending Moment from their Product Technical Catalog(2005), this may get you closer to what you are looking for. If the section #'s have changed, then you can find this information in the Anchor Principles/Design Considerations section of the catalog. I am not sure if this applies to such small screws or not. Perhaps one of their engineers can elaborate.

Try also a google search on screw bending or something similar. I am certain that this was discussed here or on Eng-tips at some point in the past. Probably the latter. Here is one link that won't get you too far....

http://www.eng-tips.com/viewthread.cfm?qid=31223&page=41

Jim Wilson, PE

Stroudsburg, PA

Brad Cameron <bsc@keymark.com> wrote:

Hello from a long time Seaint "digest mode" lurker! I have benefited
many times from the comments I see on this forum.

I often design connections using screws in cold formed steel connections
to resist eccentric shear. Little bitty #10 screws into 33 mil (20
gage) sheet steel. Sometimes the steel is as thick as 54 mil (16 gage).

The easy way out is to design this connection using the elastic method.
But how conservative is this for screws?

The ultimate strength analysis method for bolts assumes a nonlinear load
deformation relationship. The equation that governs this relationship
in the AISC Manual is:

R = Rult ( 1 - e ^ (-10 DEL) ) ^ 0.55

Sorry if the formatting is hard to read. I learned on Salmon and
Johnston's "Steel Structures", 2nd edition. Oops, now you might know
how much of an old timer I am. In this book they state that the
coefficients "10" and "0.55" in this equation are experimentally
determined, resulting in a maximum delta at failure of about 0.35
inches, using 3/4" A325 bolts. On page 135. I think this means that
the bolt is assumed to drag through the steel for almost 3/8 inch,
allowing the forces to redistribute amongst the fasteners.

Given this, I wonder whether the equations as stated in the AISC manual
for ultimate strength analysis are applicable to the dinky little screws
I sometimes use. No way will I get 0.35 inches of movement out of a #10
screw before it breaks or otherwise just gives up.

Back on page 134, they say "Actually the concept of instantaneous center
is identical to the elastic (vector) method if the resistance Ri is
proportional to the deformation (i.e. stress is proportional to
strain)." Makes me wonder what the load deformation curve of a #10 screw
looks like in cold formed steel.

Anybody got any insights or suggestions - perhaps a way to derive
coefficients appropriate for screws?

Thank you in advance for your help!
Brad Cameron
Keymark Engineering

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RE: LENTON Mason Lock

Does anyone have experiences with LENTON Mason Lock?
http://www.erico.com/public/library/Concrete/LT0958.pdf

Regards,

Martin

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RE: Eccentric Shear on Screws

From a previous life I worked on nuclear power plants and one of the
exciting things that structural engineers did was seismically qualify
mounting of electrical equipment (fuse holders, etc). There are two
references that were helpful:

"Fastener Standards", Industrial Fasteners Institute

ANSI B18.6.3-1972, Machine Screws and Machine Screw Nuts

We developed a design guide but quickly looking through it I did not see
you question being addressed. But I do not have all of the references.
The Industrial Fasteners Institute has a web site and a place to submit
questions. You might try that.

Gary W. Loomis, P.E., Senior Structural Engineering
Master Engineers and Designers, Inc.
-----Original Message-----
From: Brad Cameron [mailto:bsc@keymark.com]
Sent: Wednesday, July 18, 2007 6:01 PM
To: seaint@seaint.org
Subject: Eccentric Shear on Screws

Hello from a long time Seaint "digest mode" lurker! I have benefited
many times from the comments I see on this forum.

I often design connections using screws in cold formed steel connections
to resist eccentric shear. Little bitty #10 screws into 33 mil (20
gage) sheet steel. Sometimes the steel is as thick as 54 mil (16 gage).

The easy way out is to design this connection using the elastic method.
But how conservative is this for screws?

The ultimate strength analysis method for bolts assumes a nonlinear load
deformation relationship. The equation that governs this relationship
in the AISC Manual is:

R = Rult ( 1 - e ^ (-10 DEL) ) ^ 0.55

Sorry if the formatting is hard to read. I learned on Salmon and
Johnston's "Steel Structures", 2nd edition. Oops, now you might know
how much of an old timer I am. In this book they state that the
coefficients "10" and "0.55" in this equation are experimentally
determined, resulting in a maximum delta at failure of about 0.35
inches, using 3/4" A325 bolts. On page 135. I think this means that
the bolt is assumed to drag through the steel for almost 3/8 inch,
allowing the forces to redistribute amongst the fasteners.

Given this, I wonder whether the equations as stated in the AISC manual
for ultimate strength analysis are applicable to the dinky little screws
I sometimes use. No way will I get 0.35 inches of movement out of a #10
screw before it breaks or otherwise just gives up.

Back on page 134, they say "Actually the concept of instantaneous center
is identical to the elastic (vector) method if the resistance Ri is
proportional to the deformation (i.e. stress is proportional to
strain)." Makes me wonder what the load deformation curve of a #10 screw
looks like in cold formed steel.

Anybody got any insights or suggestions - perhaps a way to derive
coefficients appropriate for screws?

Thank you in advance for your help!
Brad Cameron
Keymark Engineering

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RE: Masonry lap length

From: "Scott Maxwell" <smaxwell@umich.edu>
To: <seaint@seaint.org>
Subject: RE: Masonry lap length

>>2" cover would be about the bare minimum allowable cover...considering
>typical 1 1/4" face shell thickness and a minimum of 1/4" clear for
>fine grout and 1/2" for coarse grout.

>Regards,

>Scott
>Adrian, MI

Scott,

Using anything more than 2" of cover means you might as well leave the
bar in the center for anything less than a 12" CMU.

However, that brings up a good point. If you do put 2 bars in one cell,
K is also dependent on the clear spacing between bars. If you were to
use #6 bars with 2 1/2" cover in an 8" CMU, K would be 1.125" due to
spacing. At 2" cover, K is 2" due to the cover. Put one bar in the
middle and K is 3.4375".

Adam Vakiener, P.E.
Structural Engineer
Southern A&E, LLC

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Subject: Masonry lap length

Subject: Masonry lap length
From: "Friis, Donna" <FriisDL@cdm.com>
To: <seaint@seaint.org>

>Adam,
>I am interested to know what masonry cover you use for bond beam corner
>bars or vertical filled cells with 2 bars (1EF). It seems like the K
>value would be quite low say 2" and hence the lap length very long
>(since our value it is divided by K.) Or am I missing something?

>Donna

Donna,

I have found that the capacities are so much higher using strength
design that I can almost always use just one bar in the center. You are
correct that if the bars have 2" cover then the lap lengths get much
larger. Usually, to the point where I specify rebar couplers. I have
only been using strength design for a few weeks so I am sure I will run
into some other problems, but so far it is working out well.

As far as the long lap lengths with low cover amounts, that is a problem
I have been dealing with since we implemented the 2000 IBC (as it used
the same lap length formula for both ASD and strength design).

Adam Vakiener, P.E.
Structural Engineer
Southern A&E, LLC

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Thursday, July 19, 2007

RE: masonry vertical control joints

Try this. It is cited in ACI 530R-05

1.19 “Control Joints for Concrete Masonry

Walls,” NCMA TEK 10-2A, National Concrete Masonry

Association, Herndon, VA, 1998, 6 pp.

Mark E. Deardorff, SE
R & S Tavares Associates, Inc
9815 Carroll Canyon Road
Suite 206
San Diego, CA 92131
Phone: 858-444-3344
Phone: 209-863-8928
Cell: 209-765-5592
mark@rstavares.com
www.rstavares.com

CONFIDENTIALITY AND SECURITY NOTICE:
This e-mail, including any attachments, may contain confidential and proprietary information and may be legally privileged or otherwise protected by law. It may be read and used solely by the intended recipient(s), and any review, use or distribution by others is strictly prohibited. If you are not an intended recipient, please notify us immediately by replying to the sender and delete this e-mail, including any attachments, from your system immediately without reading, copying or distributing them. Thank you for your cooperation. R&S Tavares Associates Inc. and its client retain all proprietary rights they may have in the information.

From: Christopher Banbury [mailto:cbanbury@arkengineering.net]
Sent: Thursday, July 19, 2007 1:43 PM
To: seaint@seaint.org
Subject: masonry vertical control joints

Does ACI publish any design or specification guides for vertical control joints in masonry?

I paid over $500 for the 2005 ACI Manual of Concrete Practice with over 2000 pages of standards and can’t find anything on vertical control joints.

Thanks in advance.

Christopher Banbury, PE

President

Ark Engineering, Inc.

PO Box 10129, Brooksville, FL 34603

22 North Broad ST, Brooksville, FL 34601

Phone: (352) 754-2424

Fax: (352) 754-2412

www.arkengineering.net

Re: PCA Mats Software

It does not currently do PT Slabs., they said it was GOING TO in 2 months (but that was 4 years ago when I bought it). So...don't get your hopes up on that, although PT is so popular in SF Bay Area with the mid-hi rise residentials going up, you think they'd incorporate it...obviously, it's not quite as straight forward as RC Slabs.

It's expensive, 3k if I remember right back then, it's likely gone up with Gas prices.

-g

On 7/19/07, Marlou Rodriguez < mbrodrig@mbrodriguez.com> wrote:

What is the going rate for Safe at this time? An all in one software that does Mat, PT Slabs, and Suspended Slabs, would be great to have in your bag of tools.

Marlou Rodriguez, S.E.

MBRodriguez Engineering Inc.

2355 Oakland Road, Suite 14

San Jose, CA 95131

Tel: (408) 432-4866

Cel: (408) 761-5013

From: Gerard Madden, SE [mailto:gmse4603@gmail.com]
Sent: Thursday, July 19, 2007 11:17 AM
To: seaint@seaint.org
Subject: Re: PCA Mats Software

Both are good programs like you said.

SAFE is more powerful for the reasons Jim mentioned.

One disappointment with SAFE, was when I was purchasing it about 4 years ago, I was told that the next version would have PT Floor design capabilities. Well, 4 years later, that's still not a feature.

But it's a good program none-the-less
-g

On 7/19/07, Jim Lutz <Jim.Lutz@bhcconsultants.com > wrote:

I used to have access to PCA Mats at another company and found it EXTREMELY simple and user friendly. It was a pretty old version, and I have no idea how or if the current version might differ. It' s very functional for simple jobs. The number of load cases and combinations were limited, and I don 't know how up to date their design algorithms are. I thought the software was useful but a bit on the primitive side —which is not always a bad thing. Output was not very jazzy on the older version.

I have also used CSI' s SAFE, which is also a good piece of mat modeling/design software, but more complicated and with a lot more features and more versatility in the design process. The nice thing about both of these programs is that they automatically create compression -only soil springs for you , but the number and spacing of the springs is all "under the hood" so it isn' t entirely clear how fine the actual analysis mesh is . They both generate required steel areas. My recollection of both of these programs was that they only told you about punching shear at concentrated load locations, and you were on your own to figure out what was going on with one-way shear in the mat. The only way I have ever figured out how to get that information was to set up a regular finite element model with my own soil springs using general modeling software , which is a pain in the butt. The other nice thing about SAFE is that you can use it for elevated slabs as well. I never used it for that, and I don' t recollect whether or not it was useful for anything but gravity loading. I do my elevated slab jobs by hand, because there is almost always some lateral load moment you have to consider at the columns .

In terms of what they do for the money, I think SAFE offers more , but I got along just fine for years with PCA Mats. CSI makes great software, but I found it took longer to learn how to run. A chimpanzee could run PCA Mats.

Jim Lutz, P.E., S.E .

720 3rd Avenue, Suite 1200

Seattle, WA 98104-1820

206 505 3400 Ext 126

206 505 3406 (Fax)

www.bhcconsultants.com

--
-gm

--
-gm

RE: masonry vertical control joints

You are essentially going to the wrong folks for masonry stuff. ACI is not really into masonry. They are involved with MSJC (masonry code) more by default than anything else.

Take a look at the TEK notes from NCMA. They are available for free by way of the website.

Another option is to look into the TMS Masony Designer's Guide. I have not looked through the 5th edition enough to know how well they treat movement joints.

Regards,

Scott

Adrian, MI

-----Original Message-----
From: Christopher Banbury [mailto:cbanbury@arkengineering.net]
Sent: Thursday, July 19, 2007 4:43 PM
To: seaint@seaint.org
Subject: masonry vertical control joints

Does ACI publish any design or specification guides for vertical control joints in masonry?

I paid over $500 for the 2005 ACI Manual of Concrete Practice with over 2000 pages of standards and can’t find anything on vertical control joints.

Thanks in advance.

Christopher Banbury, PE

President

Ark Engineering, Inc.

PO Box 10129, Brooksville, FL 34603

22 North Broad ST, Brooksville, FL 34601

Phone: (352) 754-2424

Fax: (352) 754-2412

www.arkengineering.net

masonry vertical control joints

Does ACI publish any design or specification guides for vertical control joints in masonry?

I paid over $500 for the 2005 ACI Manual of Concrete Practice with over 2000 pages of standards and can’t find anything on vertical control joints.

Thanks in advance.

Christopher Banbury, PE

President

Ark Engineering, Inc.

PO Box 10129, Brooksville, FL 34603

22 North Broad ST, Brooksville, FL 34601

Phone: (352) 754-2424

Fax: (352) 754-2412

www.arkengineering.net

RE: Steel drag strut to masonry connection

Return Receipt

Your RE: Steel drag strut to masonry connection
document:

was Tom Hunt/AV/FD/FluorCorp
received
by:

at: 07/19/2007 12:46:32 PDT

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