Basic Engineering Saves Time & Money

I am new to this forum and am impressed by the quality of the information and questions posted. Some of the questions are related to structural design, such as the gentleman building the cabin, or the person asking about hurricane construction.
Like I am sure many of you learned the trades from a parent or on the job (in my case from my grandfather). Construction practices are passed from generation to generation, but often we don’t know why certain things done as they are. We also rely on the residential construction portion of the code, essentially a bunch of rules of thumb (my opinion).
Which brings me to the point. I am lucky enough to have learned and in fact taught a structural engineering course at a university here in Indiana for about 18 yrs. I have also practiced for some 30, before retiring.
I encourage everyone to lean some basic structural engineering. When you do, you stop saying “we’ve always done it that way, and become an “inventor”, always finding new, easier and more cost effective ways of doing things. It’ easy, fun and practical.
I hope there is interest in this topic and if so, I am happy to offer myself as a resource.
Thanks to all.
Edited 9/17/2004 1:16 pm ET by David
Replies
So how do we really know you have a structural background ??? You could just be messing with us. (-:
.
I think as a test, you should have to answer a basic question. Like what's the difference between a ridge beam and a ridge board?
For extra credit, you could explain the diference between collar ties and rafter ties.
Then we'll move on to vented vs. non-vented roofs, and whether tar paper is really needed under shingles...
.
Seriously - Welcome to the board. Always glad to have a new face around here.
It's hard to be funny when you have to be clean. [Mae West]
Boss:
You are really hard hearted. I sent you (yea, same guy) the W12x26 dimensions and will be sending you the AISC table you requested. Why would someone own two AISC manuals @ $400 the set if they didn't know at least something about structural design?
But I'll bite and answer at least the first question. A ridge board is mearley a connector to hold the top of the rafters in line, while a ridge beam carries 50% of the roof load (acts as a beam). Framing w/ a ridge board requires either jack rafters or ceiling joists, while the tensile forces created by the rafters using a ridge beam must be made continuous, hence the use of steel tie straps over top of the rafters. Save some bucks by using 1x or rip 3/4 plywd to use as ridge rafters... works just as well as 2x stock. Did I get that right?
My turn. Say we have a 90' distance between 2 opposite parallel walls, divided into 3 equal sections or bays of 30' with two equally spaced columns or posts that support 3 overhead beams. The two end beams are supported at one end by the wall. The goal is to get the smallest and least cost beams possible. Are all the beams of equal size? If not, which are/is the largest or smallest? How/why do you do this ?
Edited 9/17/2004 3:58 pm ET by David
Edited 9/17/2004 4:07 pm ET by David
Well I feel good now, my question has actually spawned another posting topic!
Seriously, this is a great place for learning, but experience is still your best teacher...
As my father used to say, "if it is not miserable, you won't remember it".
I think the answer to the question "David" posed, will help me learn.
Happy Friday!
Pinemarten
David,
Are your beam ends fixed or just supported by the wall?
Ron
Supported by wall, free to rotate (not a moment connection).
David,
The three beams are the same size. If it was a continous beam the middle span could be longer.
Theorom of three moments.
Is this right?
KK
No, the sizes are not the same. Unlikely to get a 90' single beam?
David
Sorry for being so curt in my last post. I do appreciate you trying and interest.
Are three 30' metal beams welded together treated the same as three single beams?
I'm just trying to learn something.
Gotta go watch some HS football.
KK
KK:
They would be most likely treated as single beam, then moment theorem you referenced would apply. Since cost reduction is the goal, however, welding together 3 -30' beams involves high cost, since this would need to be an in-place field weld and require additional web stiffners. Then, since I did not specify a material, how do you do it using, for example, glulams, which are common in tilt-wall construction.
Thanks.
David
David,
If I get to treat as a continuous beam then the middle beam is smaller since it has negative moment on two ends and the outer beams have negative moment on only one. Like a cantilever effect. That does not seem to apply in the real world though since these are three seperate beams.
I think I could attach glulams together with some steel and bolts.
KK
Actually, I was both kidding around with you and introducing you to some of the topics that are discussed here frequently. Somtimes HEATEDLY discussed.
So it wasn't intended to be an actual "test" - Just poking fun.
And it worked, didn't it? I helped get you a nice discussion going here...(-:I like you. That's why I'm going to kill you last. [Arnold in Commando]
Boss: You're right, it did work. This is actually fun, so thanks.
By the way, your steel W section info will be mail tomorrow.
The deck, as a membrane, cannot deflect at the 40 foot endwalls like it can out in the open bays. Thus, the endwalls are able to relieve the two end beams of some requirement for stiffness. The two end beams are lighter in section than the center beam.
David I have read and reread your description several times and cannot envision the structure you are describing. Why three beams when 90 feet would become three bays with two interior beams or would require four if the outside edges rest on beams too? Why two columns to support three beams ... did you mean two columns each? If so you did not say that. I predict this question will be unanswered because the description is indecipherable.
Clay:
Sorry. Let me try again. Say we have a 90' long by 40' wide bldg. Say the 90' walls are N. and S. facing, making the 40' walls E & W. The centerline of the 3 beams and 2 columns are on the center of the 40' walls running parallel (E-W) to the 90' exterior walls. The columns are 30' and 60' respectively from the E or W wall, that is at 30' intervals. The secondary framing would then run in the N-S direction.
Does that help?
I'm in the confused camp too.
David, Welcome. If you can stick around through the BS we enjoy here, you can be a VALUABLE RESOURCE.
but I'm not getting a clear picture from the verbal description.
and I would disagree that a ninety foot long wall derives all its lateral strength from the perpendicular end walls. The roof system has to be a supporting assembly in similar manner to a diaphragm system.
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
Both Lowes and Home Depot have trained specialists on duty to help you with these framing questions.
Remember if it looks right , it must be OK
You need to describe this better. I am confused.
Bob:
So was Clay. See message #23 for clarification.
Thanks.
David. Without getting into a lot of detail and assuming the beam is uniformly loaded-the loads on the interior columns is greater than the loads at the ends of the beam at the walls. The maximum bending is over the columns. The maximum shear is just to the left & right (between column and wall) of the columns. Since this is a continuos (one piece beam) the size will be the same for all three spans design to meet the maximum positive/negative bending moment, the maximum shear forces and the allowable deflection. Technically the beam could have variable section configurations(size) throughout the length of the beam/span to meet variable stresses along the beam.This can & is done if it save money,space etc. etc. David, I know this is an oversimplified explanation but the more I say the more I need to say so I will leave the technical detailed explanation to you.
I had better stop before I say to much and get into trouble. I know just enough to be dangerous. Like one of the replies previously mentioned, my education is from "Simplified Engineering for Architects and Builders" by Parker. My copy is the tenth printing dated 1957.(more current additions available) I paid $5.00 for my copy. That ought to tell you something about this respondent. Parker has several other books that are very helpful. i.e. "strength of materials", "structural timber","structural steel", "reinforced concrete","roof trusses" and others.
This thing is now glowing from active brain cells. Forget the lateral load stuff... consider this a simple gravity load issue.
As soon as I can I will post the solution and a diagram of the load condition.
Please enjoy the weekend.
David
The beams are not the same size. The center beam should be larger than the other two. I won't go into the calculations, though. It's been 15 years since I took a structural engineering course. I do know that the columns are taking (in simple form) twice the load of the wall ends of the end beams.
Jon E
none and ALL
Sorry I did not reply earlier. Your analysis is correct were the beam a continuous 90' long. The only way I know to do that is to use steel and make field welds and add a lot of web stiffners at the supports.
I am providing the solution using glulams, so welding is not an option. The solution is a common one, especially in tilt-wall warehse/distribution centers. I'm not trying to keep it secret, just need enough breaktime to finish the dwgs and review the calcs. I don't have a computer based calc. program, so it is being done the old fashioned way. So here goes (I'll follow-up with more later):
We could just set 3- 30' bms, but there is a better way:
Set a bm across the 2 interior columns, but make it long enough so it hangs over at each end. A good empirical rule of thumb is to initially set the overhangs at 1/9 th of the interior span, or, on this case, 30'/9 = 3.33 (3'4") making the total length 36'-8".
The 2 end bms are supported at a wall and hung from the overhang portion of the middle beam. The result is the span of each outer bm goes from 30' to 26'8", a full 11% reduction in span, meaning the outer beams get smaller. The outer bms have positive moment, meaning the top edge is in compression, the bottom edge in tension.
Meanwhile, the middle beam, when load is applied to the outer bms, bows upward at the center due to the outer bms pushing down on the ends of the overhang. Remember old crown up rule. We have "forced" an increase in the crown. When bowed upward, the top edge of mid bm is stretched or in tension, the bottom edge in compression. This is just the opposite of the outer simple span bms. This tension top, compression bottom is negative moment.
When we lay in the floor/rf joists, the load must work against the induced crown or negative moment. The floor/rf loads will force the middle beam down, eventually giving C top, T bottom, or + moment. The beauty... the + and - moments occur across the same beam, so we ADD + and - giving a smaller moment and therefore smaller mid bm... even smaller than had we used simple span 30' er.
Result, all 3- bms get smaller. I need to re-check my calc, but now it appears 3 - 30' glulams would include 1085 bd feet of material, while the overhang solution requires half that.
I do this even when setting 2x basement/crawl space girders. The overhang girder has 1/2" plywd sandwiched (glue and nail) betwn the 2x. This plywd extends 12" beyond the overhng. The outer 2x lap ea side of the plywd, glue and bolt, and call it a day.
Will follow-up ASAP
David
I knew it. Do I get a gold star?
The goal is to get the smallest and least cost beams possible.
As I don't have a clue, or the math to probably understand it either:
3- 16K2 bar joists will give you 86 live 161 total/ lin ft with only 165lbs of steel each. Around $500 total and no crane necessary.
Do they qualify as beams?PAHS Designer/Builder- Bury it!
David,
You make a good point and I would like to read up on some of the basic fundamentals. I spent about 10 years in residential renovation and my father was a union carperenter but I still wonder on some practices. While in residential renovation I went to school for a BS in EE (don't ask how I went from renovation to EE). I wouldn't have the time for actual coarses but would like to do some reading up on it. Any test books you can recommend?
Thanks,
Chris
Chris:
My favorite text is Statics and Strength of Materials by Jensen and Chenoweth. It has been around forever and is essentially 2 books in one. But pricey @ $140 (amazon.com) and can be intimidating if you are not up on your math.
To get started, an alternative ($12) is Shaums Outline of Statics amd Mechanics of Materials. I don't have that one, but other Shaum tiltes I have looked at are reasonable.
I do appreciate your interest.
David
The book I got a couple years ago when I was designing my remodel is "Simplified Engineering for Architects and Builders" by Harry Parker and James Ambrose. It could probably be better organized, but it has lots of useful tables and examples.
-- J.S.
Thanks to everyone for the interest. I did not intend for this to become a structural "challenge," but thanks to Boss Hog it turned into one.
If no one objects, I'd like to let this run a few days and then I will post the solution and a PDF file (diagram) attachment. You can get the Acrobat Reader from http://www.adobe.com as a free download.
Again thanks.
Hi, David,
So, back to your suggestion that everyone learn some basic structural engineering, what academic coursework do you suggest for tradesmen/GC's to gain a reasonable familiarity with the subject? What level of math, then how many and what progression of engineering courses.
Thanks!
Not that I know anything about this....
but....
We know there are three beams and we know they are not the same size.
Two "kinds" of beams, middle and outside.
I can imagine the outside beams would be bigger because they have to deal with lateral force from the wall?????
I can imagine the middle beam is larger because the lateral force is passed through to it from both sides?????
A voice in my head says that the lateral force isn't relevent...not the beams job, but it still makes a bit of sense to me.
What is a moment connection???
Welcome to the board, David. Always good to welcome a fellow Hoosier to Breaktime.
Rich Beckman
Another day, another tool
Thanks. Beams don't generally serve as lateral force members, although I see your logic. The walls (4- assumed in a rectangular bldg) would compromise the lateral force system. Related to this, many assume the top plate is doubled in wood frame in order to give extra support for the floor/roof framing. In fact, top plates are part of the lateral force system and are in tension (being stretched under wind load). The doubling is used only to allow the plates to overlap so they form a continuous tensile member.
As "hint" check this site:
http://www.strongtie.com/products/connectors/HCA.html
Rich,
I've read down and seen that nobody answered your question. Amoment connection is a connection between beam and its support which allows the transfer of a twisting or torquing load from the beam to the support.
If the beam is just sitting on top of the post then the deflection of the beam under load will only load the post vertically. No moment connection. If the beam is fastened to the post with angle brackets, the deflection of the beam under load causes the post to deflect sideways - moment connection. A moment is a load and a lever.
Anyway, I don't get it. With the same load, the same length and the same support conditions, I can't see why the beams would be different. I'm looking forward to David's answer.
Ron
Thanks, Ron! I appreciate it. I've learned at least one thing from this thread.
I am still confused. If there is no lateral load, why do unbraced walls fall down before the roof structure is built (just happened to the Walgreen's being built in Marion)?
Someone made the point that the interior columns are supporting twice the load of the walls. That makes sense to me.
My next question would be: Where is the significant difference? If the beams are not all the same size, is the reason because one is in the middle and the others on the outside?
Or is the reason because one sits on two posts and the others sit on one post and a wall?
Or is the reason because one beam has beams adjacent at both ends and the others only have a beam adjacent at one end?
But I guess that is what David's question is to begin with.
Rich Beckman
Another day, another tool.
Rich B. anf All:
When I said forget the lateral loads, I did not mean the entire bldg is not subject to lateral forces (wind, earthquake), justthat we are looking at a small part of the total bldg. This part in question IS NOT that part of the bldg which resists lateral forces.
It is interesting that so much attention is being focused on lateral... and important because, in my experience, lateral force systems are the least understood in the construction industry. Most architects/GC's don't understand it, and it not considered at the draftsman/installer level. Probably one reason for all the devastation Florida.
My and Boss Hog's (yes Boss i'm giving you some of the blame) challlenge is strictly related to vertical gravity loads.
David
David, why in the blanky de blank did you bring this up. Are you trying to cause descension among the troops. There is no way one can give a simple answer. I know better, but here goes.
Given: A continuos one piece beam 90-0' long, simply bearing on a wall at each end and simply bearing on two equally spaced columns creating three equal spans of 30-0'. Assumed: One continuos, full length, uniform, one piece steel wide flange beam.
Answer based on the above given and assumed, the beam will be uniform in section (size) for the full length of the beam (over all three spans) with the minimum section configuration(size) determined by the maximum shear and bending forces that will occur(equally) in the two outside spans.
However, if one can assume that the beam may be especially manufactured and or fabricated as a continuos span beam with varying section configurations as required to meet the varying shear and bending forces along the beam, the section(size) will be larger between the outside spans and over the columns and smaller at the middle span between the columns. This is often done with steel construction but is not practical in most simple applications.
Proof. To calculated stresses for continuos beam of three spans where w=#/lin. ft. and L= feet.
The vertical loads at the ends over the walls==0.40xwxL. The vertical loads at the columns=0.550xwxL. The maximum shear at the walls=0.40xwxL. The maximum shear on the outside beams and the columns =0.60xwxL. The maximum shear on the center span at the columns =0.50xwxL. The maximum bending moment occurs over the columns=(-)0.10xwxLxL. The maximum bending moment at the outside spans=(+)0.40xwxLxL. at a distance (0.40xL) from the wall. The maximum bending moment at the middle span=(+) 0.025xwxLxL at the center of the span.
In a more light hearted note . Can we skip the beam, close the doors, and turn the fan on to pressurize the structure?
then in the case of more snow load all you have to do is turn up the fans. LOL Hey just kidding --just trying to add my nickle.. In all seriosness I am intrigued to the answer and looking forward to the answer.. MIke
MitreMike and All:
Have finished diagram and calcs, but did them fast so needs a ck.
The diagram will be in AutoCad DWF file. If you don't have it, the "DWF Viewer" a free download at http://www.autodesk.com.
I will send the calcs as both a Word and Txt docuemnt.
In the meantime: The solution really comes from something all of you do day-in day-out... Apply the "Crown Up" rule. So, how do you arrange the 3 beams over the 2 columns so you increase or create/force a larger upward crown or bow in the middle beam? That is the answer in nutshell.
I don't get it and I probably won't understand the math when you post it.
If you are dealing strictly with gravity the 3 beams are each supporting and transfering an identical load between supports. Treat these 3 spans as individual units and they all have the same size beam. Although there is more weight applied to the supporting posts than the outer walls it doesn't seem that should affect the size of the beam.
I'll have to get my favorite PE to check your figures.<G> And hold my hand through the explanation.
Hi Ralph,
You're right on. That's exactly the way I see it too. So we can be wrong together, right?
Ron
David,
Please don't expose us to an AutoCAD file. We can deal with JPG and GIF files. I'm suprised that the CAD programers are not smart enough to figure out how to offer a "Save As..." GIF or JPG option.
You could just copy and paste your Word file into one of these messages. Also, you might be able to paste your diagram into the Word doc. and that might work. Otherwise print it out and then scan it and save the scan as GIF or JPG.
As for the beams, Since they are all the same length and carry equivalent weights, they would each be equal. Bar joists is a good idea.
~Peter
Well you are right about file type, but I think you can handle a DXF file. It is not a orig. autocad file, but like a PDF file but only more compact.
What he is getting at is that one must have program that reads DXF which excludes probably 3/4 of those participating here.. But if you posted it and youare incapable of doing the comnversion, I'm sure myself or somebody else will get around to making it available in the more common viewing format.
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
Did you download the free viewer?
I did, and am anxiously awaiting the results. Have a feeling we will see the center beam cantilevering over the column supports and hooking up to the endspan beams by means of hinge connections.
I have pdf readers and a few programs that can open dxf or dwg files and convert them
I am picturing a larger beam in the center, though when he is making this a pure cost equation, I find that doesn't always measure up in cost/labor/benefit analysis in the field the same it does in ther engineering office.
I have my engineer spec out at least two solutions, he usually does three, and then I can analyse cost of instalation and time for suppliers to react to decide which process is best on site t actually use.
theoretical vs practical don't always agree.
That's why you often come in looking for the advice of us nail bangers, right? Good on you.
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
Good response! Wish I'd had those words to describe my gut reaction to David's thread. You're unique! Just like everyone else! Scott Adams
i see - you were talking about the viewer program he linkerd that is a free download. I seems that it is for working with a specific DWF kinf of file from the ACAD drawing web publisher. That same program says that it can embed withing hypertext so it seems there is a way he could plop it right on the screen as well.
But maybe I'm all wrong. One way or the other, we'll see his magic
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
Just download the viewer:
http://www.autodesk.com
I would and tried to aattach the setup.exe file to a post, but the file is 5+ mb and these posts only support 3 mb
I can send it as a jpg as well, but quality in comparison is poor.
Done already, tho it took 45 minutes to do.
I'll be curious when you post the dwf file if the other programs that read dxf or dwg will open it or if this is another proprietary Autodesk format that they will eventually want to license and control.
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
No . This is free download. But obviously a marketing tool.
I'd have to sort of agree with Piffin here - DXF files just aren't what most folks are equippmed to deal with.
I can deal with DXF files at work. But there's no way I'm gonna download a viewer and install it on my home computer. I have enough video games and such installed for the kids. That computer desn't need slowed down anymore.I've been doing a lot of abstract painting lately, extremely abstract. No brush, no paint, no canvas, I just think about it.
A forum like this is about sharing and mutual respect. At the expense of being selfish and a little angry, the effort I am making is far greater than the effort requred to download and install a viewer. Slow down the computer? It has multiple GB (1024 MB each) on the hard drive... this is a crummy 5MB file. Try defragging the drive. These are line drawings, not photos...if you understand JPEG and the underlying compression algorithum you would know why JPEG produces very poor line art.
Sorry, you get DXF or nothing.
Maybe YOUR computer has multiple Gigs available. But not everyone's does.
My home computer is old, slow, and full of stuff my Wife and teenage boys have installed on it. Defragging the hard drive isn't going to make any difference. (And I do that regularly anyway)
So a 5 Meg viewer might not mean much to you, but it does to me.
It seems to me that it's easier for the poster of a file to post it in a format that virtually EVERYONE can read, than to expect dozens of people to download and install a iewer just because you don't feel like converting it.
I've also gone to great lengths to help others on this forum, as have many others. But never with the snippy attitude you showed in that post.Q: Why won't cannibals eat divorced women?A: They're always bitter.
But never with the snippy attitude you showed in that post.
You forgot, he's an engineer. Who also, to date, ignored his least cost requirement.PAHS Designer/Builder- Bury it!
How was the least cost requirement ignored? By the way, an engineer I ain't.
Edited 9/20/2004 7:44 pm ET by David
How was the least cost requirement ignored?
What's the cost?PAHS Designer/Builder- Bury it!
Wuz we trolled??
Some of the early answers were right on as to using a continuous beam. As to low cost, even my cheapo DIY self would never do a part span shear connection to save some material cost, the labor of making the shear connection would be a killer comparatively (OK maybe a 500 ft long warehouse with 200 of these things mass produced in China would make economic sense. ) Hey Boss, how many part span shear only connections do you deal with in your job, bet its doggone few?? Firth of Forth bridge is one exmple thought of right off of trusses with pure shear connections.
What got me toward the end was the phrase:
"I don't have a computer based calc. program" HUH??, but a couple of $400 books?
I don't like it to be well known 'cause I like to keep a redneck image here, but at the company I work at as an engineer I have nearly unlimited access to computer based calc. programs, many whose licenses are in the 10's of $$K. A son has his own business and has about every piece of software that is proven to help with his job.
Edited 9/20/2004 8:35 pm ET by JUNKHOUND
Shear connection? There is no shear connection! Where does this come from? These are stock glulams... the outer 2 bms are "hung" from the end of the mid bm with of- the-shelf Simpson Strong Tie connectors. THAT is not expensive and the entire assembly, compared to 3 simple span beans of equal length, costs about half in glulam. The 3 simple span solution would require larger connectors over the columns offsetting easily the cost of the hangers.
This is done every day in the type of low budget projects referenced earlier.
In terms of the "consulting" cost, go back to the 1st 3 posts and see where this all began. I KNEW the answer before it was poised. The calc I'm doing are simply to provide specfic methodology to everyone in this thread as a service.
David:
Anything to save a few bucks in materials these days by making better use of physics is appreciated. Don't be concerned about the challenging nature of the discussion around here- don't let it dissuade you from participating.
A few questions, and forgive my ignorance- I'm not at all challenging your response, just reasoning out loud in an attempt to understand what you've proposed.
1) From what I've seen, and I haven't seen the calc itself, it would seem that the connection between the middle beam and the overhung end beams has to transfer substantial loads between these members to do the job you're describing. Saying that the middle beam is merely "hung" off the ends of the end beams makes it sound like the force transfer between members isn't all that great. The large force transfer means a heavy connector with lots of strong fasteners at these locations. Is that correct? And how is this different than essentially splicing the beams with connectors and treating them as a single beam?
2) If you used simple beams, the connection tying the beams to the posts and to each other would be pretty standard and not very heavy because the structural purpose they serve is merely holding things in place so they don't fall off in an earthquake or in wind etc. But the individual beams wouldn't be permitted to transfer loads to one another and hence would need to be larger than the essentially single beam with two supports that you've proposed.
3) By calculating the optimal position of the posts, you've managed to optimize the force transfer between members to make the beam to beam connections simpler, while using a long, commonly-available member for the middle beam.
4) The economics of the whole situation would depend on the total costs of the two installations. For most of us, this would include the one-time cost of a structural engineer's services to provide calcs, drawings and specs to the building department's satisfaction. For a structure like this, the cost of engineering would be EQUAL for the two approaches- in our region nobody would be permitted to construct a structure of this size (other than a barn or farm outbuilding) without a professional engineer's stamp on what'd been proposed anyway.
So: provided your design does indeed generate a net savings in materials and labour, you've proven your original point that good engineering saves money. That fits my active definition of good engineering: any damned fool can solve a problem by throwing money, material, labour and energy at it, but it takes an engineer to produce an optimal solution. And the optimal solution for a particular problem is generally site-specific. Others here have argued correctly that the TOTAL cost of the solution includes the cost to teach the people who are doing the job a new way to do things, and the supervision to make sure it's implemented properly so that lives aren't at risk, and these costs aren't borne as significantly by a more conventional approach which may not make as efficient use of materials. Those costs of novelty are easier to justify if you have several (numerous) similar projects than they are if you're doing only one.
And not to be nosy, but you still need to tell us your background in a little more detail. You said you were a lecturer in structural engineering at the community college level, and you "practiced for thirty years", but later you responded in the negative to being called an engineer. So- what exactly IS your background? Are you a structural engineer with a B.Sc. or B.A.Sc. in mechanical or civil engineering? Are you a licensed professional engineer? Are you a civil engineering or architectural technologist (3 yr diploma) or technician (2 yr diploma)? Or do you have another background? Not being nosy, it's just important to know what someone's background is so you know how much salt to take with their responses. For instance, nobody should EVER listen to me on structural engineering issues, because I'm just an interested amateur. I'm here to learn in that area and appreciate your attempt to provide us with some new insights, whatever your background may be.
Wuz we trolled??
Pretty sure everybody knows what BS is. MS is more of the same. PHd, piled high and deep.
No offense intended. Your "redneck" image is fine. Certainly enjoy your posts.
I called it quits with BS.
Had hoped that we had somebody here, iguana (David), who might actually offer interesting engineering insight. Without the BS, lizard or otherwise. PAHS Designer/Builder- Bury it!
Interesting.
Your first introductory post here left the impression that you were an engineer >
"I am lucky enough to have learned and in fact taught a structural engineering course at a university here in Indiana for about 18 yrs. I have also practiced for some 30, before retiring."
In the contezxt of engineering knowledge, and teaching such for 18 years, you state that you "practiced"
Now I am wondering what it was you practiced?
Violin?
Medicine?
Law?
The context of an engineering introduction sure led us to believe that it was engineering you had practiced.
One way you ignored the pre-requisite of lowest cost was that you involved about a dozen consultants in this discussion to discover the method needed to solve the problem. Shall we say fifty buck an hour for twelve guys? That adds $600/hour to the cost of the job, LOL
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Thank you. I was just getting there.PAHS Designer/Builder- Bury it!
Please see post #71. Go back to 1st 3 posts.
And the non-engineer?PAHS Designer/Builder- Bury it!
Let's say he saves a size on those outboard beams.
Whaddya think your yard will charge you for one of these?
View Image
That has to be a heavy GA steel to handle that joint. It isn't small. They don't stock it so there would be a UPS charge added.
I'm guessing seventy bucks each.
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About the same they would charge for a connector to attach the 3 simple bms.
guess again.
Not that engineers should be guessing at anything.
A post top connector is made from 12 to 18 GA steel and is readily available at most lumberyards I deal with.
the hinge end connector you hint at and show above is made from six gauge steel and takes an exra effort to procure because it is uncommon..
BTW, my 2001 CD shows pricing for a thousand of them to break down to around $25/ea . With the rise in cost of steel and the price breakout on smaller quantities, I don't think I was too far off.
I have a guy who could probably build them for 60% of that, but who would have the engineering liability without Simpson behind it? I'll go with the Simpson if some engineer pitched this to me to build.
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"About the same they would charge for a connector to attach the 3 simple bms.
"
I happen to think some more on this and find yet more cost in this attachemnt. Your comparisson seems to suggest that if these are little more than post top connectors, then the total cost doesn't get impacted by adding the hardware. But you still need post top connectors as well for a total of four connection hardware pieces instaed of only two.
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I was looking forward to hearing from you and getting a chance to use this new fangled downloaded vieweer you talked me into.
still working on it?
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I am anxious also.
My software isn't ACAD, but I can export a file as .dxf or .dwg. I did that with a couple files, but the viewer failed.
The viewer only opens a .dwf file. Whatever that is. I thought all ACAD files were .dwg. Looks like they have thrown something new into the equation.
Drawing web format. a simplified compression of the ACAD drawing for reading and markup
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I thought the purpose of a DWF file was so you could send stuff to others, but it couldn't be edited or changed like a DXF or DWG file can be.
Kinda like a PDF file for CAD software...I watched the Indy 500, and I was thinking that if they left earlier they wouldn't have to go so fast.
I don't know m,ore than what I rad where I downloaded it. practice would be enlightening, but it looks like I won't ge the chance since the promised drawings and calcs are undelivered as of yet. Maybe the calcs are harder than he thought without an engineering calc program. If so, that makes the point I was arguing - that any thing that gets too complicated for a basic guy to figure on a calculator or a typical formula is going to be too hard to incorporate in a structure and will have hidden costs, like this waiting for the proof to show up...Engineer ( or non-engineer as the case may be ) promises a unique idea with possibilities and then disappears without proffing it.
Oh well
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Piffin & Boss Hog: I'm addressing this to you all since the best I can tell you seem to be the old pro's.
I'm not exactly new but this is the first time to try to enter into any of the discussions. In the past I have ask a couple of question but mostly just listened to what everyone else had to say.
When this topic came up I thought I would put in my two cents. But I must be doing something wrong. I have replied three times but nothing happens. No replies are comments. What an I doing wrong? Maybe there is something I don't understand If I didn't see the postings I would think that I had not replied at all. Any and all suggestions appreciated.
Thanks, None
I'm not Piffin or BH, but maybe I can help. Try these:
http://forums.taunton.com/tp-breaktime/messages?msg=47618.29
http://forums.taunton.com/tp-breaktime/messages?msg=47618.36
http://forums.taunton.com/tp-breaktime/messages?msg=47618.57
http://forums.taunton.com/tp-breaktime/messages?msg=47618.84
Jon Blakemore
Feeling like the invisible man? That seems to be David's job, LOL
I've been reading your commnents here all along.
But they don't highlight to you by default. Look in the left column of thread titles. Near the top of it is a drop down menu that defaults to "show me all unread messages". If you click the arrow and see all the choices there, one will be ALL or something like that which will allow you to see discussions you have read and posted to already.
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I think the solution is quite elegant. If there are enough of those beams then the cost of engineering could be recouped in material savings. For residential work, though? Better take it out of the book and save the time and cost of the engineer. The cheapest solution is the one the building inspector isn't going to argue with you about.
There's also a lot to be said for conventional structures that people following you can understand easily. I don't want to build a house that can't be changed in the future.
Ron
David,
If you have any kind of an image editor (like MS Paint, maybe) you can display you image on you screen, then just touch the "Print Screen" key, open Paint, or whatever you may have on your big new computor, paste into Paint and Save As a gif file.
Those are line drawings, not photos...if you understand GIF and the underlying compression algorithum(sic) you would know why GIF produces very fine line art.
SamT
You,re right. I'll try it
David,
Is this something like what your talking about?
I drew this in Paint and saved it in jpeg.
Joe Carola
Exactly!
David,
Chill out. I know you are just having a bit of fun and trying to be helpful. I also know that the post I deleted was very negative and may have set off your defensive response. Probably everyone here knows I can be a BIT too personal. I was out of line. This is my apology. Get to know everyone here and enjoy our company and put up with our shortcomings.
I was having a bad day and felt it was time for you to post your solution. For one thing, I had actually considered the possibility that W might be reelected, and that alone made me think about another four years of dead Americans. But I may be wrong about this too.
I hope you won't judge this forum by my responses alone.
To everyone else, I think I may have set a tone that does not fit here. Will try to control my impulses in the future.
Lastly - This forum needs some good structural advice. I, as a retired military engineer, more of the civil and industrial persuasion, could benefit too.
Are we cool?Les Barrett Quality Construction
On that dxf file posting thing -
Nothing to "agree with piffin on" I was simnply stating a fact. Facts don't take agreement, they stand on their own, right?
But the thing for David to agree on is that the fiorst rule of public speaking and teaching is that the speaker must use language that his audience will understand. (That's why the holy Spirit gave the gift of speaking in tongues to the Apostles)
If a speakeer talks over peoples heads, he loses his audience. I was trying to explain the language to put his pictures into if he wanted folks to see them - and if they ever get posted in any language, I can repost in gif . call me the TRANSLATOR
;)
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Welcome to BT, David. Seems you have already passed the "can I handle the BS" test and with only with a tiny falter! If you think the place is a bit rough-and-tumble now, wait 'til winter. ; )
I haven't got a clue as to the answer of your question, nor do I care. If I was building such a structure, I'd simply have it engineered. Ya know, just as the engineer must know engineering, the rest of the trades must be experts (or experts in training) in their fields, too. In the standard sorts of structures that are the largest bulk of what's actually built, most framers (and ex-framers) will know enough to size headers, but not to address a question such as the one you pose. How many engineers would decide to take on the power troweling of a concrete floor in the structure you describe? You get my point.
There are quite a few guys here who know quite a bit about various trades, but to me, the sort of engineering question you pose isn't relevant for most of us who actually erect structures for a living (for me, I hope that part of life is now in the past tense!). Interesting in an abstruse way perhaps, but not relevant to what most folks here do for a living.
Hope you'll hang around and get to know folks here at BT. It's a good little community and pretty open to sharing both knowledge and opinion. I think you'll fit right in.
You're unique! Just like everyone else! Scott Adams
David, I am afraid that I must have totally misunderstood your original question. In the spirt of the challenge, I submitted an answer, that I thought addressed your question, to the best of my limited abilities. So far no critique of my humble efforts have been forth coming. It seems to me that the question evolved, degenerated or whatever into more of a computer thing. Since I'm an old hand in the construction business and not very savy along the computer lines, I really can't add anything to the current discussion.. Anyway, if I have offended anyone I apologize. None
Thanks David for your reply. I now know where you are going. This is neat and fun stuff, but I'm afraid that in the residential construction world it is not to practical. In most places and cases there won't be an engineer evolved and the architect &/or designer will not want to take the time to do the detail drawings necessary. This is the type of thing that can give a good framer a bad case of the heartburn. And if there is not someone on the job to make sure it is done correctly everyone gets the heartburn.
This "cantilever/negative bending moment" technique can sometime be used on say a 2 ply beam or girder. (i.e. two LVL's. side by side. One ply extends, cantilevers, to the left beyond the support to it's inflection point and the other does the same on the opposite side to the right of the support). This eliminates the the need for a special hanger to tie and support the adjoining beam. However you still have the same problems as noted above.
Just for fun, lets not only hang the outside beams at the outside deflection points, lets also hang a center beam from the inside inflection points. Now we have three beam sizes. As I see it that portion of the beam over the columns would be the largest, the outside portion of the beam would be the slightly smaller and the center portion of the beam would be the smallest. This would require still less material. Correct me if I'm wrong. Lots of fun. None
The structural (important!) part of your comment really stuck out in my mind. Do you know of any such courses in the Chiacago area?
Thanks for the point.
To consider building codes a "bunch of rules of thumb" could be deadly. Building codes are the minimum acceptable standards. In some circumstances it is possible for the code official to vary from the minimums, but you had better check before you build it.
David is right, though, in that planning can save time and money. The build-it shows on TV demonstrate the many horrors of last minute decision making and inadequate planning.