ClearCalcs Expert Hours with David Hourdequin (Pt. 1)


Wednesday, April 26, 2023
2:00 PM

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Structural Design Concepts: Heavy Timber Engineering Pt. 1 (Churches and Chapels)

About this event

While wood has been used as construction material for centuries, the use of mass timber or heavy timber in structural design is only emerging in the last few decades, and not everyone has a clear understanding of what it means.

Additionally, as steel and concrete became the preferred alternative materials in construction, there’s a surprising amount of expertise that goes into designing with heavy timber that not many structural engineers are confident with it, even though they might have a natural interest in timber as building materials.

Join our Structural Design Lead, Laurent Gérin, and David Hourdequin, President and Owner of North Carolina-based structural engineering firm D. Rémy & Co., to learn more about designing with heavy timber for churches and chapels.

We will discuss some of the most interesting heavy timber engineering projects that David has worked on in his careers, such as St. Joseph Adoration Chapel in North Carolina, St. Thomas the Apostle Church in Maryland, and Horizon Community Church in Ohio.

This is your opportunity to learn from his insights regarding what worked and what didn’t, explore complex scenarios that demonstrate timber’s efficient working capabilities, and unpack structural design considerations when working with timber - all while having an opportunity to ask questions directly from our expert himself!

In this webinar, we will cover:

  • Introduction to David Hourdequin and his structural engineering career history
  • Overview of timber frame engineering & why it is unique in structural design, and what makes a timber frame engineer different from a structural engineer?
  • Projects details: -- St. Joseph Adoration Chapel, Belmont Abby, NC: An exquisite glass-walled chapel constructed with a grid of 6x6 timbers on a five-foot cubed module in a diamond configuration, connected with Timberlinx(TM) and utilizing swaged, stainless steel rod lateral bracing. -- St. Thomas the Apostle Church, Waldorf, MD: A triple set of heavy timber, square, stacked, three-level tension, compression, and tension rings creates the structural frame replicating the traditional architecture of Orthodox churches found in the Carpathian region of Eastern Europe. -- Horizon Community Church, Cincinnati, OH: Crossed diagonal glulam trusses with steel, kerf plate, bolted tension connections supporting a twenty-ton steeple.


Connor: All right. Hello, everybody! Welcome to a an an earlier morning expert hour really excited to have this expert hour because we haven't had one since I think November or December. So I think this will be a really good opportunity for everybody to learn from a a real world structural engineer, and and projects that he's actually worked on.

It looks like we have quite a few people still just coming into the waiting room. but for the sake of time, because I want to make sure we have as much time as possible to speak with David. Let's go ahead and get going.

So, as you guys know. this this version of expert hour. We're gonna be talking about hever heavy timber engineering. If I could talk with David or to can.

So we gotta go through this one as always you guys have probably heard of a 1,000 times about clear calculation. Clear counts is a cloud-based structural calculation software. Combining powerful faa analysis with. Hopefully, you guys have seen easy to use design tools. wood, engineered, lumber, steel, cold form, steel, concrete. I'm. Looking to be more accurate. eliminating waste of time and available everywhere.

So the 2 hosts, and then we'll definitely introduce David.

You guys have probably spoken to us. We've got Laurent, who's a professional engineer and also our North American engineering, contact, content lead all these new calculators that you guys have seen being pushed out in the past few weeks. He's leading that work which I know from my end is super exciting to see. and then myself

I'm. Our director of customer success. So here, to make sure you're successful and clear, counts whether it be training sessions, help content anything like that?

Laurent Gérin: All right, and I think i'll I i'll take over from here. I get to be the lucky one who introduces David First of all, David, thank you for being here with us today. Just a little bit about David here for everybody else who Hasn't had the chance to meet him. Yet David has been about 60 years in the construction industry, so since he was in high school, always had a connection to it, and learned a lot from it right now. He's the President, owner of the Remy Co. And he's doing a lot of engineering, especially with heavy timber engineering before that, about 20 years in structural engineering and construction management, and then the last 25 years focusing on his real passion, which is heavy timber, engineering, and through all that I think he's learned a tremendous amount. He's touched about every single part of the construction industry, and so now, sharing his knowledge, and we're lucky enough to have him here to to share his knowledge and bit of a a cool thing that just happened. David recently released a new book actually on consulting engineering success, and it is available right now on Amazon. Kindle encourage you all to check it out. I just had to read of it over the weekend. It's a very short read, very well written. It reads really well. I think some of the cool things that I found how oysters can help you find new customers.

But the 4 way test, which is actually from the Rotary Club, and very, very simple yet useful guide, I think, when you've got to make tough decisions here, and then I think the one that we probably all identified with at some point in our lives at wraps right now, overworked and underpaid. It's actually the name of a chapter. So i'm sure you all identify with that. Encourage you all to to take a read. And I think just overall the cool thing here, David.

You know it's. It's been extremely transparent vulnerable with this book, and I think same thing with today with the presentation, and then we had a chat before. Feel free to send your questions, even if they're hard questions in the chat. David's is an open book today, and he's here to to to basically help out share his knowledge.

So it's crazy to read the book we've got. David here today. Take a you know. Take advantage of it. Ask whatever questions you have. We're gonna go over some projects that he's worked on today, as I think it's gonna be really exciting.

Excuse me exciting. And one last thing here, if you want to ask questions, and i'm talking about that at the bottom of your screen, you should be a little chat window here. Just type your your question in here, and we'll be going through these as we go. Don't worry about interrupting or anything like that, we'll make sure that your questions come through, and and we'll be more than happy to have a, perhaps a. Q. A. Or we can do it as we go as well.

Let's see how it goes. all right. And with that I think I will hand it over to David, who's going to start speaking to us today about specifically church projects that he's worked on that Really, I think looking at the pictures that that David sent before they really show off the capacity of heavy timber here to make beautiful beautiful structures, make efficient structures, and also give us all a cool engineering challenge once in a while. So

Over to you, David.

David Hourdequin: Okay, let's see if we get into share screen mode here. I don't flub this too badly. And for the photos down here to do to to Okay.

All right. So the pardon me. got all these selected and we're gonna go to full screen. So get our. I guess everyone can hear me. Okay, I I I see up on the screen that i'm the guy that's doing the talking, so I just want to welcome everyone. It's so great to have you all here and to talk about my favorite subject and my passion in life.

Vocationally at least, I often tell people what if I had to choose between working on a hobby project and doing doing timber? Engineer? I'd rather come in here and design a trust and then go home and do the other stuff. So that's kind of how I feel about it.

This particular job was one that was a lot of fun for me itself. Belmont avi college over there, Charlotte. It's called Saint Joseph Adoration Chapel. and this came to me. Courtesy of Josh. Come, and I I hope josh is on today. I I think he had planned to attend. But interestingly, Josh just led me into some really fun and exciting projects that, architecturally, you know, it's it's not about size for me. It's just about exquisitness, I think, in the design. So i'm gonna go through these slides and and then I will come back and talk about some specific subjects.

and if you have any questions I'm going to ask Laura to be the moderator, just put them up on the chat box and and, Laura, you feel free to interrupt me anytime, and we'll deal with whatever anybody has.

But you know, if you can hold off till I go through it, maybe, and then we'll go through the questions. Maybe a project at a time might be a smoother way to do it. So

without further ado. Let's take a look at this

David Hourdequin: interesting thing about this structure is the grid framework here. These are all 6 by 6 that are connected, interconnected here, and you'll see the inside of it all glass everywhere.

The grid is 5 feet by 5 feet and when I, when I started on this project. It reminded me very much. I think it's Dawani, the architect from Arkansas.

The interesting thing about Dwani's work. If you can see my corner is up here where timbers intersect it, he would always have a whole, and so I guess it was a piece of square tube, or something like that that was in there, but I always like the fact that the light passed through these holes. and but I couldn't talk anyone to doing it on this job. They they had pretty much decided what they wanted to do, so let's see what else we got here. Another close up.

David Hourdequin: I love ecclesiastical lighting so pretty inside the chapel.

It's not a very big building. I don't know maybe 2020 feet wide, or probably 25 feet wide, maybe 40 feet long, not big at all. and there's the kind of a sandwich of it. And these are like. This is a really interesting trust system, because it's like 2 parallel cords instead of a scissor. Trust not not uncommon, but a little bit unusual. You don't often see trust configurations looking like this.

Josh C.: You're supposed to send me the details of your

David Hourdequin: hey, hey, Josh Coleman, I see you. We we should probably let Josh have a few words here when when the at some point. So, anyway, I I don't know what happened to the I hope I have the drawings. But so. because this chapel is all all glass everywhere. The only thing that had were a couple of closets and restaurants. This is up at the front corner, and the restrooms on both sides. and so you know, with all the glass. We couldn't get enough out of the shear wall, so we put diagonal tension rods in it.

and I. I took this photograph a couple of years ago, and I went over there, and this one was slack, and I I had to call people up and remind him. You know you got to keep those things kind of snug. Fortunately, I think this was the way it was installed to begin with, because the none of the glass it cracks. So, thanks thanks for to God for that.

Here's another shot. These are all switched fittings. Josh found these, and they're connected to steel brackets down here at the bottom and up at the top. I thought it was a pretty good bracing system. and these are these are in both directions, and there is. This is the lateral force resisting system for the for the chapel.

So let's go back. And Josh, I thought I had a couple of slides, but but I don't. But anyway, what I wanted to let's go one more.

What I wanted to share. Principal it was that wherever timbers crossed in here. timberlinks connected the discontinuous pieces. In other words, if there was a continuous piece, let me see if I can on this slide.

Yeah, sorry about that. Don't mean to make you dizzy if there was a continuous piece in here like right here. That was fine. But we needed to find a way to connect these 2 pieces here that were interrupted by the by, the bottle core of the Trust. and and same thing within the trust courts. Everywhere there was a discontinuous piece. There was a timberlinks across that. and and it's if you can look that up.

i'll leave that to you on your own. I thought we had a slide of the of the connector, but for some reason it dropped through the cracks, as things often do. But anyway, a a timberlinks is a tensioning device that's that has a piece of all thread to 2. Looks like sleeve anchors with pins at each end, and the pins are expansion pins. So once you put it together. You could crank on it like an old time car, Jack, and tighten the pins up, and it locks the joint together. And so. if you put. My theory was to doing this. If you put a PIN in the center of the timber. there is some inherent moment resistance, because the the PIN several links could take tension, and of course the fibers on the nearest side could take a pressure whichever side it is. So there were quasi moment connections in every connection in here.

and I thought that was the most interesting part about this.

I will say, of all the projects I've ever done, parents wise. It's certainly one of my favorites, certainly certainly the top 5 for sure. And the josh, if you're on, and and we can hear you if you'd like to add a comment. Chime in. there you go.

Josh C.: Hello.

David Hourdequin: Yeah, we hear you. Josh.

Josh C.: Yeah, I would just say this Isn't: Quite structural analysis comment. But we put these whole wall bents together on the ground, laying flat, and then pick them up with a double hoist crane, so you could like, basically lift it horizontally, and then rotate it in the air with the 2. Hoist 2 2 different cables, and then we had to thread it down through between the trees, and then turn it 90 degrees, and but the whole time, you know, once you got vertical, it was so stable. of course. little Dicey going from a horizontal. But yeah, and then just that that was the key to to weave in these. to even these timber links together on the basis that, like you couldn't assemble this vertically. It had to be all kind of piece together on the ground, and then, once everything was locked in and the timberlinks were tightened, and then we could stand it up and fly it in.

David Hourdequin: Thank you, Josh. And and just to terminology for those of you that are not into heavy timber, engineering, or timber framing this post and this post and and the it's your only trust right here all the way across the other side is typically we call a bent and timber framing. And so what Josh was talking about pre assembling is this entire frame laying flat down, and then picked up with a crane and set it place, and then you set the next one, and then you set the interconnecting timers.

and I guess Laura back to you. There was some questions, maybe, that you all had about this, that you'd like to ask.

Laurent Gérin: Yeah. So just to remind you, if you guys have any questions, you can put them in the chat box, and also just unmute yourself and ask them out loud. But you know we like to to keep it casual here. One question I had for you, David, actually with the with the glazing here, and you've got some pretty complex trusses here. How do you consider deflections here. so to make sure that they don't get transmitted to the blazing.

David Hourdequin: Well, when the glass breaks we just try to use smaller paints of glass, and this truss is so inherently stiff. It was incredible, and usually when I put in set glass. Josh, you probably speak to this better than I can. But when you inset a glass like this. I'm pretty sure it was all really heavy plate or safety glass.

and and and there is some tolerance built around the frame. In other words, the glass doesn't fit perfectly at the timber. It's probably an eighth or 3 16, maybe even a quarter of it, shy in each direction and and a little molding. Hold it in place. That are They're cocked around the glass. Josh: you you have anything to add to that

Josh C.: Yeah, as far as I know. Can you hear me?

Yeah, yeah, As far as I know, it was kind of like a storefront window type detail where there was a the C Channel, and then I complementary one, so that there was a a a good bit of and like it's all relative, right, you know there was enough tolerance within that frame that there was. It was a little squishy.

David Hourdequin: Thank you, Josh. Anything anything else wrong?

Laurent Gérin: I I like the thanks, Josh. I like the the squishy factor, if that's the very underused engineering term, I think. Of course, she is a good term. That's what timber does when it gets to to the K. It becomes squish. So

we've got a few questions here, one from Jim Fan Joy. Jim. I wonder if you if you want to unmute yourself and ask it out loud, or I can read it if you want.

Jim Fanjoy: Oh, yeah, it took a second find me on Mute. I was wondering. I it looks like there's a lot of a lot of squares in that trust, and not a lot of triangles is, or some of those. No, for most of those null force members that just keep the glass from moving around.

Josh C.: or what?

David Hourdequin: Well, actually, this is not technically what we might call a true trust, which is an assemblage of triangles to span some distance. I guess one definition it. It is essentially a a moment frame. Trust. It's it's Every connection is is a moment connection in it, and so it didn't need to be triangulated. It was designed with moments in each direction, so I hope that answers your question. But yes, I mean good observation. It's not triangulated, and and it it was done like that, because the architect wanted to see it this way. And so the only way around this when you you're gonna induce moments and the trust connections if you don't triangulate it. So we had to deal with those inherent moments.

And that's what those connections we're doing like like right here. I believe this member was would have analogous to be in the plane of the Trust, and then this was a crossing number. Here all the crossing members were connected with these temporal links, which pretension the joint. Now some would argue that's not reliable, but I mean this structure has been up for a long time, and it's it. The service ability factor is excellent, so I think I think bottom line is, we guess correctly. I You know that's about all I can say anything.

Yeah, sure.

Okay, Should we go to the next one overall.

Laurent Gérin: Yeah. David, we just had one more question here that actually kind of 2 questions about connections here. So we've got Geo. Condo. Geo. Hey, it's been a while and Ray so if so, Geo is asking if Timberlinks is a kind of a product, or if it's a method.

and then Ray asking on top of the timber lakes. Did you also have some traditional mortise and 10, and join me in there as well?

David Hourdequin: I I, if there was there wouldn't there. There wasn't much of it. Maybe some auxiliary screws. I don't remember it's been 20 years, but

Tim, a timberlinks is is the proprietary name of a particular kind of connector, and it's spelled t I. M. E. R. L. I Nx. Timber links, and you could look that up online, and it'll give you all kinds of design data for it. It's an incredible device under the right circumstances. I've spec thousands of them. and they're just nothing else. They'll do the job quite like they are where where they're where they fit in with the structural concept.

Laurent Gérin: Thank you. Thank you, David, and and thank you, Glenn, and sent the link to the website as well. So if anybody wants to check it out, check it out in the chat. And Glen has sent the link.

David Hourdequin: Okay. Okay, David, I think, ready to go to the next one. Okay, this is. Let me let me get these all selected here

Connor: while you're pulling that up, David? There's actually just one question that came in from Caleb really quick on that last project.

He was wondering if you calculated the moments individually at each of those joints, or if you used a rule of thumb there.

David Hourdequin: No, they were all. It was put into a finite element analysis, 2D frame and done that way. I you know I have to confess I You know you younger engineers that are coming along that are learning analysis, kind of. I think that's kind of the way to go, but you know we can get off on a tangent here philosophically, but I've always tried to keep the analysis, simple and conservative. So almost always I use 2D frames, and I just take the worst case situation, and I analyze it. Put the gravity loads and wind loads on it. Look at all the load combinations and the worst stresses, and and away you go. So the answer to the questions along with the question. I guess they were analyzed, and and that's how we came up with the capacities we needed, and it turned out that that the timberlinks had more than enough capacity the the way that we used it.

Laurent Gérin: Okay, this is horizon community.

David Hourdequin: This is really a fun project, because Dan Dan concert may be on here, he can. He could add some comments. I did this with Harmony Timber works. Gosh! I don't know how many years ago, and this was a this was all blue, laminated. Every every component in here was dug for a glue lamb. and it was probably the largest glue lamp job I've ever done it. So I I asked Dave Shetti. Some of you may know, Dave. He passed away here a number of years ago, but he was probably the United States pre eminent glue lamp engine here, and they've lived not too far from me over in Central North Carolina. and I asked Dave if he would like to be the engineer record on this, and let me be the idiot doing all the calculations, and and scared everybody to death, and he said sure he'd be glad to.

and and he had a few comments that were that were good. But by and large everything worked out just fine. This is this is in the and what they would call the Northe. This is a community church at Cincinnati, and interestingly, these, this wall was curved, but everything in here is square. So these are like chord segments, and you can see the Arts members in here and then back here in this area, very at the far end you have intersecting gables. They're always a lot of fun, because the boundary of the intersectic gable, both the but the interconnection between the trusses and the trust themselves. All form attention, ring for the load in the center of the interconnected gables. because they gotta go somewhere. And so they're resisted by these ties in in both directions. So let's let's just continue on here.

It's another shot.

This is the intersectic gable up in here. You can see it coming to a peak. So when you apply a vertical load at the peak, each one of these hip members wants to wants to push the column out, and so you've got the bottle cord of each trust I can like. A tension rang all the way around that square, holding everything together. There's another shot of it. We Haven't gotten to the good part yet

whoops. Okay, More the same.

This. This intersecting gable is in in the church sanctuary right over the center of the naive. You've got a tranceet going to the left of transit, it going to right and and the Assembly area back behind you.

And and you can see these arts members here. This is just a typical trust that was in there for the rectangular portion, however, out in here is where the interesting part of the design was, You got a curve truss here. You got a curve bottom chord. Trust there again. It's all blue lamb, and we'll we'll see close up with these connections. But there there are one inch tables on steel knife plates that the plates are not visible there. In this case there were. I think, they were either 3, 8 or half an inch thick, and the plates are are in slots in the timber, and we call them either live plates or curve plates in the typical frame industry. And so you have. You have them here, and you had a crossing out here and and it in this in this section right at the King post you had. We had cross plates going up to the King Post, and then a knife plate going in each of 4 directions, so that steel assembly is socketed up in there. You can't see it, but it's the one that's doing all the work. And the interesting thing about this job. Was that right here where this intermediate web member is at vertical? I remember that that one and that one, and the 2 on the far side of the of the intersect, to gable, to find the corners of a £30,000 cupola. That's 15 tones, folks, that's that's like. Well.

what's what's that? 1010 sitting up there on the roof trying to push things down? It was a pretty challenging thing to run the numbers on, but and I've got a shot at the exterior. You could see that steeple. It's it's pretty incredible.

They gave us some relief. They were. They were recently going to do it all in brick, and I think they wound up doing some stone veneer, but it didn't help much originally weighed £45,000, and they figured they took £15,000 out of it, and so let that in. So let's see what else we got here.

This you can see the bolts up here in the night place at each end, especially right up here at the King Post. That's what this member is. That's the king post of the trust for those of you that are Don't deal with first terminology. I know a lot of lot of you typically do us mainly structural steel and concrete, and maybe like what framing shirt service there.

It's another shot of it here. That's a better close up, and you can see how everything is is bolted together by his night plates. The photo looks a little fuzzy to me. It probably is to you, but you'll just have to forgive me for that. And then this is back in the the main area. I think this is about 45 feet across from left to right and the and the arch intersected trusses for 65 feet long, or something like that. Oh.

there's a beautiful shot showing that intersected transept.

Whoops. whoops

So there's there's the assembly area again. Let's let's get out here. I want to show you some. so there's the stable right there. This is. This is the little jam that weigh £30,000, and at each corner is where it came down on that on that vertical web member of the Trust. and I can't remember exactly how that was frame. But there was a piece running up the rake and down the other side, so I guess, for all practical purposes, it it was this. this part of the trust was loaded with that vertical load traffic. So it a load going across that face, and it going across this face and all these loads just work themselves down into each of the 4 faces. But it was a it was a challenging little design.

So let's go back to the middle. We'll stop right there so any questions? Oh, by the way, the tension in these trusses was about £70,000. I'm thinking something like that.

How many bolts we got in here 2 4 6 8, 10, So you know that's that's quite a few. probably at 4 or 5 kips. So 50, £60,000 of tension at least in that bottom chord. Another thing while i'm thinking about, I want to mention when you're dealing with blue lambs. or or any other current member for that matter, but particularly for glue lambs. You have a radio stressed radio tension stresses here as that member is under tension. It tries to straighten out. and when it tries to straighten out the laminations of the clearly I'm trying to come apart. And so you always have to check these arts members that are under attention for a radio tension.

So questions Laura.

Laurent Gérin: Yeah, thanks for showing that, David. That's a super cool one, and that I like the Shit Relay analogy with this people. There, we've got a question here from Geo. Good to base. If the steeple be a truck as well, or would that just screw things up.

David Hourdequin: Yeah, I I don't see where that would be any advantage, particularly those walls of the staple were like sheer walls as far as when loading could start, which, by the way. put an interesting twist on the analysis, because that when load had to be generated into this frame, interesting thing, as as I talk about that about when loads is that the allowable stresses under one load and in any low combination, including when can be increased by 60%. So seldom. I'm not saying always, but seldom does it control the design, except for maybe top chord.

Trust stress reversal in super high wind loads. You get into 100 6,070 mile an hour wind zones.

And if you've got a simple gable, trust that ordinarily the top courts and compression of the V. Of course the tension all of a sudden. Now the stresses reverse completely, and the top courts are in compression. So you've got to take into account that that complete stress, reversal intention and compression reversal. But here, I think, just the simple 4 walled structure was probably the easiest, and and it wouldn't have if we had trust anything up on the steeple. It wouldn't have changed any frame it down here, so you know kind of pay your money and take your choice.

Laurent Gérin: Thanks, David. What that i'm wondering. I i'm guessing i'm probably not the only one on this call who's never specified a curved glue land member before, and you mentioned about radio tension, and that being a consideration.

Is there anything else that say? If I wanted to specify a curved glue lam the first time I should be aware of, or I should consider when i'm specifying it.

David Hourdequin: Well. if you look in the back of the nd, that the most important thing is the layout. And and, for example, if it's a flexible member you want, you want the best fibers in the bottom of the glue, lamb. And and so there are. If you look in the in the nbs, you'll see that flexible members have different low combinations than than the axial tension members, for example, axial tension members like this one.

The lamination quality is balanced and symmetrical around the center lines. So that's that's one thing to learn. The other is that and the beauty of this and and i'm going to I'm going to slide off into an adjacent area. But when you're to sign and curve, played connections with bolts or pins. You can use still pens or bolts either one like these are. If you have green timber. you cannot put 2 2 rows of bolts on a common plate. because, as the timber shrinks, it will split either down one of the rows or in between them, or something like that. It's so. The capacity of each bolt has to be reduced to 40% of its nominal capacity. So that's a horrendous reduction, and so to get around that.

Maybe in some cases you can have an isolated strap at the bottom, and another isolated strap at the top. That way the straps could float as the as the wood shrinks. But if you have one solid plate with 2 rows of bolts, then that's no no in green timber now with glutam. It has to inherent moisture kind of much less than that, you know. 12%, Max, probably. And so when you have a look at when you have a timber that has a moisture content of less than 19%.

Then you can. You can put 2 rows of bolts in here. Now. Normally, you wouldn't put more than 2 rows of bolts in in heavy timber, but in glue lam you can put more rose to the 2.

The most I've ever done is 3; but in order to do that, the distance between each row has to be 5 inches, and then you have to have 2 and a half inches of edge distance out to the side of the timber. So if you're putting 3 rows of bolts in this glue lam, it would be 15 inches deep. and and I think you know, if you're embarking in the Blue Lamb area, I would I would.

I'm trying to remember the name of the company something structural wood systems, structure, wood systems. and evergreen. And Alabama has got a staff of engineers and people down there that can help you with something like that. So if I was getting into this for the first time, I would have them kind of look over my design, and then, once you put it out for bed. They're probably going to be one of the booters now. That may give them an insight track. But

you know, in this game I i'm just so against conventional design. Bid build as opposed to a design build. I think you'll put everybody together and then do it. Anyway. Got a little far field there. But one thing led to another law, hope that answer question.

Laurent Gérin: It did it. Yeah, Honestly, I I think we all appreciate the insights here at this is really really cool. One more question here from Hironimis, he's asking, what does the analysis for the additional radial stresses look like? So would you take the orthogonal tension and then add a bending component just because of the eccentricity? And does that affect the connection? Design?

David Hourdequin: No, I mean when you're checking for radio tension. There's a fairly simple formula in the in the timber construction hand.

I i'm not going to look it up right now, but the Timber Construction Manual Sixth edition.

If you look up radial tension in there, it'll give you the formula, and you just simply put in the the radius of curvature and the size of the member, and and that formula will will give you a value that has to be less than a a controlling or limiting value. I I think that's a about as complex an answer as I want to get into at at this stage again.

Laurent Gérin: All right, thank you, David. I i'm just. I was going through the nds really quickly here to see if I could find a formula. But I I didn't make it in time, so it. It is in the N. Ds, I believe, and and you'll be able to to check out that formula.

Thank you, David. I think good to go to the next project. If you're if you're good.

David Hourdequin: Okay. I'm. Good.

Let's see that one is St. Thomas the impossible. Josh: If you're still with us. I'm: sure. I'm sure you'll have some interesting things to say about this. This. This was another phone project with Lancaster County. They were frames.

Well, come on. Oh, Here we go. all right.

I don't know who that is, but but they're having fun. So i'm going to come back to this slide. This this is actually attention, Strap and I'll. I'll explain it here in a minute. So let's see if I could get to. Okay, here we go. So this structure had 3 square areas that were co-joined, or at common walls in in an elevated stack. And and the intriguing thing about it was that this: the top play up here is attention, Ray.

You could see the rafters all going down here. They're connected at the plates going around it, and they're trying to push that thing out. If you imagine a load down at the peak, it just wants to spread everything apart there. So up at these corners you have to put straps around the corners, or or knife plates inside the timber, or something to take the tension. And and the way that you do that I just divide up the forces in the into summarize into 4 components. I don't worry about this. This reactor is going on for the right. It's the ones that the hips that define the tension ring, it's so when you put all the design loads in this, this has a certain compression in it that it gets transferred into this corner, and it's trying to shove the corner in in a direction parallel and collier with the hip, and so you can divide that up into components, so you can design a strap that goes along the plate in one direction and the plate in the other direction to take that tension, and so that that was the intriguing part about this.

It's so we start. We start cascading down through the structure. So you go from the tension ring, and then you've got these posted here. Now this is gets laterally stabilized later. Don't worry about the don't worry about the racking. That's that was all done with shear walls. So you come down here, and now we've got another plate line around here. Well, with the loads on that.

That that now is a compression right? You know you're you're pushing that you're pushing up on it. And so it kind of works in reverse. And then down here You've got another tension right and right there is that strap that he's working on, I think. and it's a pretty hefty piece of steel it. Usually you'll find that that for its plate still can be used for this, and i'm not sure why that's so far apart. Normally, you know, if you can, you're trying to get them up in the middle. I i'm sure there was an aesthetic reason for this. Nothing wrong with it. But you can see the the the top of the corner post cut off here to have a a housing to engage that raptor so that that thrust goes into the post.

and the post is trying to come out of the screen and toward your left, and these straps keep everything retained. and that hands to follow it's like he needs a break that looks like hard work to me. Here, you see this strapping place going around this tension right here at this level. and and I think this is probably one of the most exquisite joints I have ever seen. Josh. My compliments to you. I showed this to Dan Kaiser earlier today, and he said, I have got to try to do that. So any of you that you know, or good at geometry, how you could construct this free end. Just so for for $8. Josh will send you the secret formula. So there is another shot.

St. Thomas, the Apostle beautiful shot, looking up through the core of the intersecting cascading squares.

There it is completed absolutely beautiful. I can't take credit for how pretty any of this stuff is. I'm just. I tell people i'm like that. I am to engineering what an orthopedic is to medicine. I just work on the bones of the building, and I try to keep them from breaking, and that's what the North Pis does. and you get an idea of the volume. Josh. Anything you'd like to add.

David Hourdequin: Josh: You there. Hello!

Josh C.: Hi! Can you hear me?

David Hourdequin: Yeah, we can hear you

Josh C.: all right. Wonderful. So yeah, I would just it's sure was a lot of fun to do. David. Maybe you can flip back one slide. It's like a longer shot. So you can kind of see. Yeah, actually, that was perfect.

So the we actually assembled the the upper cupolas on the ground. and then the lower hip rafter. You see, that has kind of an overhang. We we set each of those hip rafters individually, and then we able to kind of tether it down on the rafter tail outside, and just hold it in the position.

So once all 4 hips were just sort of floating out there, and then we lowered the whole cup of the down and nestled it into those tip.

So a lot of precision fit there. But everything went really nice. And yeah, that that was me in that photograph, putting those lag bolts in that mail strap. I think it was 15 on either side. It was a My, let's just say it was a long day of of running that impact gun.

But yeah, this was a fascinating one, because they didn't want any interior columns, and coming up with a a system that could could support all those layers without sending into your columns.

It's a lot of fun, and the PIN. Will I call that the pinwheel doing at the peak? Yeah, that that does always work out really nice, and it's sort of sort of in the vein of that reciprocal framing idea with this whole another world. But yeah, this, my my little contribution to that.

David Hourdequin: Thank you, Josh. I I I've just reminded to this point that this doing one of these projects is just really a team effort, and and i'm just sort of the idiot guy in the process aesthetically, because. you know, architect gets a whole of this, and then a contractor gets a whole of it, and then they turn to people like Josh at like has to county timber, frame and and and say, you know. pull this together for us. And so, if you're the structural engineer working on one of these the aesthetics are generally worked out for you.

Now. as you can experience you'll have some pretty strong thoughts yourself. Give me a second. You'll have some strong thoughts yourself about the aesthetic side of things.

But ultimately, you know my my my thing is I'll. I'll suggest what I think is is a good alternative, and then. you know, and after that it's up to the designer like like Josh or Dan Kai or somebody to say No, we want to do it this way, and it says, No, we don't want to do it that way, and that would kind of remind me of a a chapter in the book where I talk about cautionary notes is that sometimes a client will want you to do something that you just don't think it's a good idea, but you can make it work structurally.

And so I think it's important to to forewarn a client and remind him on the drawings of the decision he made it so many words. In other words, if it's a situation that may be problematic. pointed out right on the drawings that that this condition could be problematic, maybe hard, hard to maintain, maybe impossible of weather proof, whatever the circumstances are. where it ran counter to your own good judgment. Then I think you owe it to yourself from a liability standpoint, and also to the client to point that out again. Black and white, big, bold, square, outlined on the drawings, and and we do that quite a bit. Any other catches.

Laurent Gérin: Thank you, David. And then that that was really cool. Thanks, Josh, for for bringing in some more insights here and cool to hear that you're the You're the lucky guy in the picture with the gun. We got another question here from here on this. If you want to unmute yourself, maybe you can. You can ask it yourself, or happy to repeat it.

Oh, he's at the office. No problem. So Iran is asking here the the pinwheel joint. Did you use any kind of connection in there? Or are these purely just bearing on each other?

David Hourdequin: Those are all those are all toes from above. Right? Josh is. I remember ** Josh C.**: That's right. Yeah. So they they all nest into each other, and then once everything's cleaned out. Then you can screw around in one direction. Then we usually go the opposite direction, so that each members screwed into the one next to it in both directions.

David Hourdequin: So you have. We have 2 toes, screws, and each member looking down on it. One goes down to the right, one goes down to the left and in each joining timber. So is that right?

Josh C.: That's that's right. Yep.

David HourdequinOkay. What else?

Laurent Gérin: Question for you with the analysis here, I think you mentioned previously. You You prefer to keep it simple with a 2D frame analysis or something like that. Obviously this is quite a it's not a 2D analysis of something like that with attention. Ring, then the compression rings. Did you do this by hand? How how did that look like?

David Hourdequin: Well, you, you could do it easily enough by hand, you know. Just put a you know you've got You've got half the load going into to this diagonal and the other half going into that diagonal. So you divide that into into 2 components, and you could just do long-hand calculations. You put a point load up here. You got some uniform load on here that doesn't amount to a whole lot. It just costs. Take half two-thirds of the load and put it, I guess, or third, anyway, whatever it is, and and and you you can. Then. just using what am I trying to say? Won't? Come to me, anyway. Yeah, just simple statics you can. You can determine what the compression is in this member, and it will have a horizontal and vertical component, and there's your extension rate. The vertical component is taken care of by the post and the birds mouth. This member will have a notch in the bottom of it, and of course, to hold this member to to the tension ring. You have to screw it down into it to resist the forces that that it has in it, that want it to slide out. In other words, if you don't restrain this diagonal hip member with screws to the post, then you can't. You can't develop the tension. So. But I no, I don't do a frame analysis on that, and I, you know, if you stop and think about most structures, it it's easy enough to come out. Come, figure out a 2D frame within it that you could analyze. Now I know the results are a lot more sophisticated in 3D analysis, but you know, and and God bless you for doing it. I know a lot of these small structures. Just don't have enough fee in them to do a super sophisticated analysis. I mean, if this was larger, more complex, I mean you wouldn't dream of doing it into the analysis. But but for simple structures like this I I just don't see a problem with it at all. and I think this is a simple structure to me.

Laurent Gérin: Thanks for sharing. I think this would have been cool to see and to hear about. When I was taking my statics course in university, and and learning a little bit more about this is the real world how it works really cool.

David Hourdequin: That remind let me just make a comment about that. You know the first time. I don't know how many of you have gotten involved with common wood framing, and since it connectors. But when I first. when I first entered into that world, you know I would look at every component, I would say. Well, this one needs an L 34 and this one needs a l 32, and whatever it was, all around the structure now it might have.

I might have 8 or 10 different straps around a roof. I put that job out, set of plans out in the contract. Got a hold of me since. Are you nuts? I said. What do you mean? And he says he says we'll never get all those in the right place, he says. Tell me what the tell me what the worst load is, and that's what i'll put everywhere, and I said, I get it so there you have the message. You know. It's like. you know, in a simple structure. Take the worst case and apply it everywhere. You know I I know Jim. This to follow Isn't on the line, but I I remember just a quick aside with snow loads, and I would I would go to great details, to analysis, analyze the fraction of the ground, snow load, and the roof system.

and Jim says, You know I always just put the groundload snow load up there, all of the things being equal, because, he said, sooner or later going to have drifting loads, and you're going to be right back where you started, and he's exactly right. So I think it's important if you're doing small structures. If you're not done high, rise buildings or bridges, or something like that you need to. You need to learn shortcuts that by hand you can either check your your computerized calculations or just do it by hand, and often you could do a trust longhand quicker than you can load the data into a into a a finite element analysis frame. Go ahead, Laura.

Laurent Gérin: Oh, thanks for thanks for sharing David. We got one more question here from Glenn Glen. Do you want to come on? If you would like to unmute yourself.

Glenn: Sure, I was just kinda curious about if you can hear me, the the lateral system that you use for these these heavy timber structures, is it? Do you connect like she being to the trust frame? Or do you use intermediate intermediate like joy, our studs, or how do you kinda analyze the our designed for the lateral and the structure such as this.

David Hourdequin: Okay, Well, this this slide is a good illustration, so it it may or may not apply here, but but normally these timber frames are decked.

I would say more commonly with with 2 by 6 tongue and groups sheathing, and, and, as you all know, it has a limiting, a diaphragm, a capacity of about £70 per foot and and allowable stress design. And so sometimes you can accomplish it with just straight backing, provided that you have other structural auxiliary bracing to counteract lateral load like diagonal br. Then then they have to be overlaid with structure, wood sheeting to develop the diaphragm capacity in the root. in the walls. in a temporary structure the walls normally pass outside of the timber frame, and the reason for that is, that these posts that support the structure will tend to shrink over time and move. And so you don't. You don't want joints to be opening up inside the building. So what happens is you? You allow the the wood frame all to pass outside where the where the wood frame wall is at a post. Then you connect it to the post to to transfer the the sheer wall loads into the post that go down to the post connector, and and if there's not a post convenient to do it sometimes you have to use an embedded Simpson I. Or something like that. So that's how that is done, and then on the inside. there's a there's a usually a 5, 8, or 3 quarter of an inch gap space are made out of oriented strand board, or something with the like between the timber for a post and the inside face of the frame wall. And and and that strip is goes up the entire length of the post. I wish I had a detail, and I can't sketch here, but i'd show you. But let's say the post is 8 inches thick. Well, that that continuous piece of oriented strand, or to be about 4 inches wide up the entire height of the post.

and and so that gives you an opportunity to talk interior sheathing like drywall, or or one by telling a group or something behind the post. So, as the post moves with, change it more. Your content no joints open up. And so that's probably a long way to answer the question. But

I hope I I hope I answered your question if I didn't come back at me again.

Glenn: So so you build like a traditional stood wall on the outside. That's only connected to this at the at the post, then on for your shear walls.

David Hourdequin: Yes.

Glenn: okay, thanks. I appreciate it.

David Hourdequin: Yeah. Now, as I said, if it's interrupted by. you know, you gotta look at wall openings, of course, and and and if they're wall openings in it, you've got to use a you know you may have. You may have to. You just tie down at the jams of the openings in addition to the timber front, but usually usually you try to try to find enough shear walls that go from one post to the next in each plane to take the to take the ladder loading in it.

Seldom do you ever run into a situation where you can't do that now, If this was an open pavilion, a completely open structure, then the open pavilion has knee braces in both directions for the post, up to the trusses and to the plates.

and in that situation, when you have lateral wind load, then then those braces take, take the lateral load, and and you sell them whatever needs sheathing up in the decking, because the tributary area of the wind force going into a into a frame that has need braces on it. It's usually fairly narrow. So you're not looking at a a diaphragm sheer situation of any consequence.

Let's see, we got 53. You want to look at another slide, or what do you want to do?

Laurent Gérin: You know what, David? I I think up to you If you want to quickly go through another project, or we can also, I think, if anybody else has got questions for David in general about his career, about his work, about some of the projects we looked at feel free to share them. I think we've got a few minutes here, otherwise. In the meantime, David, go ahead. I think, to to to quickly go through a one more project.

David Hourdequin: I'll tell you what before I forget. I wanna I want to share it something with you guys. you're smart.

Can everyone see that contact information? I guess. Can you see it? Okay. So this is my email address. Dr. H. Dr.

There's the URL G. R. M. and I want to. I want to tell you all a little bit about the timber frame engineering Council, which is part of the Timer Frame guild. And oh. so the the URL for the guild is actually I don't have it correct on here, but it's,, and on there you can find the link to the timber frame, engineering, council, and all kinds of documentation reports, instructions, example, drawings, example. calculations, in some cases sample specifications and whatnot.

and if you think you have an interest in heavy timber, please please come, join us. The dues are nominal, and you won't find a greater bunch of guys in the world to work with. I mean, you know everybody that I've ever met in this industry is, is super committed to S to the quality. You know.

Everybody is so focused on doing an outstanding job, and it's unlike any other sub contract trade in the construction industry. I can tell you that because I've been involved in all of them, and and it is absolutely, in my opinion, the most outstanding and the most fun at conferences are a blast.

And and there's still so many things that we're trying to learn about heavy timber. And so there's lots of room for innovation and creativity, and those of you that are thinking about working on a master's degree or a doctorate. You'll find lots of topics to explore in the heavy timber gill, but or heavy timber industry. But if you have any questions or later, something comes to you, please don't hesitate to send me an email or call me at this number. Always go ahead and help somebody learn something new. So

Laurent Gérin: and we've got Helen Bots here who just shared the link to the the timber frame is guild as well in the to chat, so feel free to take a look here.

David Hourdequin: So with a few minutes that we have remaining we've got. Just let me show you this. Josh. I apologize what we we say. That's not sake, Martin.

David Hourdequin: Oh, how you going.

Laurent Gérin: Well, Heck. You know what, David, I think we're. We've got 3 min left, so I think, for for everybody's time. We'll probably just to stop it here, if that's all right with you. That's fine. That's fine. Yup.

Laurent Gérin: Yeah. But I think, David, thank you so much for your time. This was super super cool, I think. Oh, we've got a question here from Caleb, and I think, Jeff. we'll we'll use these last couple of minutes. If people have questions in general for you, David Caleb is asking here. Does the timber frame Gill have dumbed down courses for architects?

David Hourdequin: Oh, do do they have dumb down courses for? Listen. All of their courses are dumb. We're all bunch of dummy's just trying to learn from each other seriously. Yeah, a lot of architects belong to the timber frame guild, and and you'll find a number of architects around the country, not too many, but a few that that just try to specialize in timber, frame architecture, and and we think that's great.

The the biggest problem that I would say we run into in the industry is is working with architects who are not familiar with timber framing and then trying to school them into design principles. And and you'd be amazed at how many architects and engineers out there don't know how to do a design, or even I sketch up the concept of a simple work and trust so it it's a little bit disconcerting. Anyway. This is Father Martin's chapel. By the way, you can see it on your screen. I just think it's cool. Who's got the big hole in there, and there's the thing that connects it all together, and that's the moment connection. By the way, just for the fun of it. I had to throw that in there, Joshua, if you don't mind that's a really cool, and it's all stainless, I believe. Right.

So, you guys that are dealing with common lover, you know, come on over to the timber frame side and and do some fun stuff with us.

Laurent Gérin: Awesome. And. David, if you don't, mind i'll just i'll share my screen again. Just so we'll go over the the next sessions coming up, and I think you're in one of them, so i'll just share a Briefly. Webinars coming up. I next week, Connor here, actually 2 weeks from now Connor will be running a short webinar on designing columns in residential structures, and then the week after that David is coming back to do another one of these Webinars, and this time he'll be talking about commercial buildings. So office buildings, different kind of buildings like that, and the different challenges that that brings.

And the week after that we'll also be looking at wind load calculations for residential structures. Some of you might have noticed we've just released our main wind force resisting system, load calculations. So if you want to take a look at that, we'll be going more in depth into how that works, and what that looks like. and you can find that I sign up at Kerkowscom slash Webinars

David Hourdequin: and check out the book, consulting engineering success. You'll love it, I think. I promise i'll refund your money if you don't like it. Don't let go go to Kendall and Amazon and and download it, and and enjoy it, and tell me what you think

Laurent Gérin: absolutely, and i'll. I'll just show it again here, and I posted the link in the chat. If anybody wants to go and and purchase it really right, I personally, I really encourage you reading it. It. It was a very enlightening read, and and very fun to read as well. So right now it's available. It's an ebook, and we're working hard on getting the paper back up. We're. We're days away from doing that 2 or 3 days at the most that it should be up and running this paper back.

there we go. That's awesome, awesome. And with that thank you all for attending. Thank you, David, for your time, your knowledge, your insights. Thank you to everyone who participated as some great questions and shared their experience. Josh, in particular, I think, thank you for coming in and bringing in your your perspective from the construction side. That was really cool, and we'll be running more of these. I'll also add, if you're on here, and you're like you're thinking, hey? I've got some projects, I think, would be cool to show on here. Send us an email. We are super happy to to discover what what everybody is is building, because we've all got some really cool stories, some cool projects.

And the goal here is that we can all learn from each other, and i'll come out with with better work, faster work, and and I think. Yes, please please share. If if you're interested in this, you're gonna get a quick survey at the end here by email, I believe. Please fill it out. It just helps us make better, webinars. If there's anything that that comes to your mind, and as always, you can reach out to help at 3 counts if you've got any questions.

And David also shared his contact information. I apologize. I didn't add this to the the the Powerpoint. But perhaps, Connor, if you want to just put that in the chat briefly, so people can write it down again. I think you did share it earlier.

David, but otherwise thank you. Everyone for Ted. We'll, you know we'll we, If that's okay with you, David, we'll include your contact information in the the follow up email.

David Hourdequin: Yeah, that'd be great. Thank you so much. Thank you all for listening, and I especially want to thank Dan Kaiser. Dan was the designer on the horizon. Community Church. What a great job that was! So Hats off to you guys that are out there doing that great design work. Josh and Dan and the rest of you. Thank you so much for coming.

Laurent Gérin: Thank you all. I wish you a lovely end of your day.

Bye, bye.

Your speakers

David Hourdequin, President and Owner, D. Rémy & Co.

For more the six decades,David has served in nearly every capacity in construction and private practice.

Starting in high school, he worked his way up from washing windows to owning and managing his own construction company.

He earned a BCE from the University of Florida in 1964, followed by service as an officer in the U.S. Army. While working full time in construction management, he earned an MSEM in 1992 from the University of South Florida.

David spent 10 years doing structural engineering on a variety of steel and concrete projects. He has spent the past 25 years specializing in heavy timber engineering—his life-long passion and joy—and serving others in the timber frame community.

David enjoys a wide variety of hobbies—especially reading and writing—and spending time with his wife, Anne, and their four shared children and six grand children.

Laurent Gérin, P.Eng., North America Engineering Team Lead

Laurent is an experienced structural engineer passionate about all things structural engineering and applying theory, whether in groundbreaking new software or designing innovative new bridges out of aluminum.

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