00;00;04;19 - 00;00;11;28
Madeline Richardson
Welcome to enhance, an AEC podcast, where we learn the why behind AEC professionals so that you can learn your why.

00;00;11;28 - 00;00;23;01
Andy Richardson
Okay, so you've got some technical questions for me I guess. Next you've written those out. I guess I put a front of them out for you. Did you want to hit me up?

00;00;23;03 - 00;00;26;05
Jay Fraser
Yeah.

00;00;26;07 - 00;00;42;08
Andy Richardson
So just as a, I guess, introduction for the video. So we're we're just jumping into this, some technical questions you have about. And Jay Fraser. Yeah. Is with Fraser Construction. And so we're just going over, I guess some, you know, structural engineering questions you might have.

00;00;42;08 - 00;01;04;27
Jay Fraser
I did, construction management degree. Yeah. What we learn, I call it, you know, structural engineering light. Yeah. Like Bud Light. Yeah. I don't go nearly as deep as you are. There's some things that, I didn't really even learn in school. I'm trying to learn them, you know, here on the job. One of the one of that is all the codes and loads, section.

00;01;04;27 - 00;01;25;19
Jay Fraser
You see it often on the first page of the structural sheets, first page of the architectural sheets. Sure. And, we Fraser construction refs, Butler printer and metal Buildings, which has a, now released omni design software. You got to enter in a lot of the codes and loads. Thanks. So yeah I'm going to ask you some questions.

00;01;25;19 - 00;01;34;27
Jay Fraser
So I can understand what all that is. Even better. So what is the, the codes and loads mean? You know, in structural engineering, especially in hurricane prone areas.

00;01;35;04 - 00;01;57;02
Andy Richardson
So codes and loads I don't know where that terminology came from because I mean really we just call it design criteria. Okay. So we're you know, engineers are like I guess I'm a little nerdy, but we call it design criteria. But like, this is a job you, you're working on right now. Okay. So campus Commons in, Bluffton South or May River, South Carolina, but so these are the codes and loads here and the building code.

00;01;57;02 - 00;02;22;19
Andy Richardson
The IBC dictates what should be on the plans. So and we talked about it on our podcast, which is AC dictates the design loads and that whole book there. So this is the as this is the I rc I just grabbed a couple books here, but, IBC is somewhere. Here's the IBC here.

00;02;22;22 - 00;02;48;26
Andy Richardson
So the IBC, here's the IBC. You know that book, this is the 18 version. And then, this is the ASC seven right here. So this is, this is what we have to follow just for loads these two books. But, the good thing is eight so there's 2 to 2 references to use. One is the ATC, which I think you have.

00;02;48;28 - 00;02;49;17
Jay Fraser
Right.

00;02;49;19 - 00;02;50;27
Andy Richardson
Yeah. The access to. Yeah.

00;02;51;00 - 00;03;16;03
Jay Fraser
The, free website I've gotten good at dropping in a map and on the, on the project site, and you click a button and it'll tell you what the what that area's wind speed is and seismic wind speed. I guess that number usually is good to go. Seismic is a preliminary number until the geotech pause and then it's over ruled right.

00;03;16;03 - 00;03;25;08
Andy Richardson
Well, so the code allows you to select the as default size. So you have site class.

00;03;25;08 - 00;03;25;26
Jay Fraser
Yep.

00;03;25;28 - 00;03;38;02
Andy Richardson
And then seismic design category site class is the soil that's on site. And you can have an A through I think d ABCd and there might be more.

00;03;38;03 - 00;03;43;18
Jay Fraser
Soil and that's like is it anywhere from rock to loose sand. Yeah. So in between.

00;03;43;19 - 00;04;09;18
Andy Richardson
Right. And so what happens is the soil and interacts with the earthquake. B for two ways. One is the way the seismic activity propagates through the soil is part of the issue. And then how the building reacts to the soil. That's a different issue. But but really what the primary thing with regard to the seismic design category is how the, the earthquake propagates through the soil.

00;04;09;18 - 00;04;31;07
Andy Richardson
So that's where because if you think about like, like a wave that's traveling like a noise wave even, and it's traveling through water and it hits the air and it hits it differently, right? It's the same kind of thing. So, so, the earthquake waves travel. The motion travels differently through the soil. Like from the where the earthquake epicenter is.

00;04;31;09 - 00;04;50;14
Andy Richardson
That energy travels differently through soft soils as hard soils. And then when it hits like, let's say it travels. And this is why Beaufort County is such a bad area. Okay? Because Charleston is the epicenter of earthquake activity. There is no fault in Charleston, by the way. So it and we.

00;04;50;14 - 00;04;52;11
Jay Fraser
Call that like I went into a weird spot.

00;04;52;13 - 00;04;58;05
Andy Richardson
So I went to a, a seminar. It's been about 15 years ago, and this guy was a geologist.

00;04;58;11 - 00;04;59;11
Jay Fraser
Epicenter, but not a.

00;04;59;11 - 00;05;08;02
Andy Richardson
Fault. He said it's an epicenter, but it's not a fault. And if you look at it on a map, there's definitely an epicenter, but there's no quote unquote fault. And so,

00;05;08;04 - 00;05;11;07
Jay Fraser
Like how what faults or lines like something to see rocks.

00;05;11;14 - 00;05;35;16
Andy Richardson
Yeah. So like California has fault line. We do not actually we don't really know what causes it. He just said this is the geologist was just saying like basically there's pressure buildup that's happening there. And we really just had the one Charleston earthquake in the 1800s, the late 1800s. But it's propagates through that soil and then it hits a certain type of soil here, and then it does something different.

00;05;35;16 - 00;05;57;13
Andy Richardson
So it's kind of like that thing I was saying about going through water and then air. Okay. How does that work? So that's what the site class is. And it helps dictate what the seismic design category is. And in this area it's either a C or a D usually, but sometimes meaning seismic design category C or seismic design category D, and it depends on your site class.

00;05;57;13 - 00;06;23;10
Andy Richardson
And it also depends on how close you are to that epicenter. Okay. So the closer you are you know, so northern Beaufort County is a little closer to Charleston, southern Beaufort counties further so southern Beaufort County oftentimes is right about 278 actually how it 278 where if everything's equal meaning site site class D northern is usually going to be a D southern is often going to be a C site seismic design category.

00;06;23;12 - 00;06;29;09
Jay Fraser
The Savannah get off the hook for seismic just like the Savannah River. Yeah I mean breaks up the third.

00;06;29;09 - 00;06;50;03
Andy Richardson
Well it's not really because of that. It's just further away. And so if you look at it, is that like almost like a topo map as you get further and further away from Charleston? So obviously the building code. Going back to your question about codes and loads, I mean, pretty much the building code says what has to be on the plans in terms of the information.

00;06;50;03 - 00;07;10;19
Andy Richardson
And so it tells you got to have wind speed. You gotta have, you know, seismic site class S1 s, which you have in your questions and all those things have to be listed out specifically. And there's a section in chapter 16 that tells you exactly what you have to have. But but I was mentioning the ATC. That's one resource.

00;07;10;21 - 00;07;33;13
Andy Richardson
Unfortunately, the ATC is going away okay. That website. But fortunately the good news is AC is is picking it up. It's picking it up and it's going to be a free. Yeah, a free version. And actually where we've started using that internally for our resources. And we found that it was a little bit of shift for us, but we found that AC actually has some better up things.

00;07;33;13 - 00;07;33;29
Andy Richardson
Concur.

00;07;33;29 - 00;07;34;08
Jay Fraser
Yeah.

00;07;34;10 - 00;07;52;26
Andy Richardson
Yeah. It has some aspects of it. It's get snow loads and things that the ATC and also it is sort of puts it all together for you and it's free. So anybody listening to this can just use that. And you can type in the either the I think the address or the like the lat and long and it'll just populate that data for you.

00;07;52;28 - 00;08;02;01
Andy Richardson
So that's pretty much how you get all the design criteria. And I think the term codes and loads might have been building of department or.

00;08;02;04 - 00;08;04;16
Jay Fraser
That's comes from the layman construction.

00;08;04;22 - 00;08;07;25
Andy Richardson
World. Yeah. So, does that answer that question? Yeah.

00;08;07;25 - 00;08;24;28
Jay Fraser
For seismic, I got some wind enclosure questions for you. Okay. There's wind exposure A, B and C that's basically. Are you surrounded by pine trees and urban blocks as a right.

00;08;25;00 - 00;08;25;10
Andy Richardson
Yeah.

00;08;25;10 - 00;08;29;19
Jay Fraser
So and C is you're on the open sea and B is average. Yeah.

00;08;29;21 - 00;08;35;28
Andy Richardson
So the building code, pretty much says C is default.

00;08;36;00 - 00;08;36;29
Jay Fraser
Okay.

00;08;37;01 - 00;09;02;10
Andy Richardson
So you have what they have two aspects of it. Number one is there's a term called surface roughness okay. Actually. So that's not something that you would normally need to deal with except you need to know what your surface roughness is in order to determine what the exposure is. And so the surface roughness is the same. But surface roughness isn't infinitesimally small.

00;09;02;13 - 00;09;24;08
Andy Richardson
Thing. So in other words, I think about like the, if I had it on grid paper. Yeah. And I was looking at a one foot square, then this square would be a surface roughness C okay, because it's either grass or water. And the next square over might be a B, right. And the next foot square might be a b because it's a tree.

00;09;24;10 - 00;09;51;09
Andy Richardson
You know, and then the next one over might be a D, because it's, D has a specific criteria. A, A and D are very special. So A is like urban and D is ocean, but B and C are pretty clear cut, B is surface roughness is suburban. So tree. So like houses that are closely spaced apart and also trees.

00;09;51;12 - 00;09;51;20
Jay Fraser
Yeah.

00;09;51;23 - 00;10;09;24
Andy Richardson
So if you think about it, what is trying to do with the code is say it's rough in the wind would be broken up by those irregularities, whereas C is, grasslands. Yeah, effectively. And and then D is like ocean.

00;10;09;25 - 00;10;13;06
Jay Fraser
Yeah. Like right against the, like the side of this building might be.

00;10;13;06 - 00;10;34;04
Andy Richardson
D well, you have to have at least so there's a special criteria for it because you could have a river that was C you might have a river that's also D, and I'll explain. So it has to do with the surface roughness. So you have to know what your surface roughness is, is either B or c. And then you from there you can determine your exposure.

00;10;34;04 - 00;11;03;05
Andy Richardson
So a surface roughness b that extends for more than for 1500 or more feet beyond the building for I think 30ft or less is a exposure B and or vice versa. If you don't have that coverage around the building, then you're a C. So that's basically a quick answer to it. So you have to look at having what we do is we actually go in and create a little radius around the building every time.

00;11;03;05 - 00;11;24;20
Andy Richardson
And we we put that in the file. And then we go a 1500 foot radius around that building. And if it's if it's got the trees and the buildings around it, then it's a B. And if it doesn't for and then you have to look at the full radius, because if you had a quadrant or like a sector that had a high wind, like had a high C, then that wind could come in that sector and and b a C exposure.

00;11;24;20 - 00;11;43;10
Andy Richardson
So that's a bit of a, a summary of that. So the best way to do it, we actually go into Google Maps and do the distance measure and do from the building out 1500 feet. And then kind of like draw a circle around that. And then we look at that and say how much surface roughness do we have around it.

00;11;43;10 - 00;11;46;02
Andy Richardson
Is, is it mostly B or is it mostly C?

00;11;46;06 - 00;11;50;14
Jay Fraser
I thought you guys just went, yeah, that's a lot of pine trees over there. Yeah.

00;11;50;16 - 00;12;09;04
Andy Richardson
No, we actually have a procedure, that we, we have for doing that again. That's, that's the long and short of it is every job we have a Google map, we go in and do that little diagram. And we also every job we have a AC file and we put that into the file.

00;12;09;06 - 00;12;31;13
Jay Fraser
Last question on this. The codes is the wind enclosure. Is it easier or was what's the hardest for you to design a building with the roof and four walls, a building with a roof and no walls, or building with a roof and some partial walls and soffits and things.

00;12;31;15 - 00;12;37;19
Andy Richardson
Well, that's an interesting question. I mean, are you saying about the the enclosure category or are you saying like.

00;12;37;19 - 00;13;00;03
Jay Fraser
Difficulty level, the relate the the enclosures create uplift and then you got to design the holding down to all that. All. Yeah. So, I don't know if having four walls makes it want to blow over. Like, the walls are like a spinnaker sail. Yeah. Or having no walls makes the roof want to fly off like an airplane wing.

00;13;00;05 - 00;13;04;00
Jay Fraser
Or if having some partial walls slows everything out of whack.

00;13;04;03 - 00;13;20;25
Andy Richardson
Yeah. So the code has, it has, I think 3 or 4 criteria. Categories for enclosure. It's enclosed, partially enclosed, open and partially open. Yeah. Each one has a specific definition.

00;13;20;25 - 00;13;29;17
Jay Fraser
So partially enclosed and partially open to the layperson's. Like let's, let's just take them the glass half full, half empty. Given a different box. Yeah.

00;13;29;17 - 00;13;51;04
Andy Richardson
And I'd have to look at partially open, but I can tell you that the enclosed has to do with it has to do with, like, the windows on the front of the building and the windows on the, on the other three sides. And so like if you think about your typical I used to use, I don't know why, but a lot of your big box stores, they have a lot of glass on the front.

00;13;51;06 - 00;14;08;14
Andy Richardson
And I'm trying to think of a good example, but but you really most of your, like, Dollar General or, you know, I guess that's more of a small box store, but same point. It's got a lot of glass in the front and almost no glass on the other three sides. And so the wind goes in there and it has nowhere to go.

00;14;08;14 - 00;14;13;04
Andy Richardson
That's the basic premise of it. And there's a formula for that.

00;14;13;06 - 00;14;16;23
Jay Fraser
And I like pop the top because you've pushed it. Yeah.

00;14;16;23 - 00;14;38;16
Andy Richardson
So it's a positive pressure. Okay. That your answer is so it's 55% positive or negative pressure, and I say 55% because there's what they call it. So with windows or what they call a velocity pressure. Yeah. And so a velocity pressure is like the best way I can explain it is, you know, you run down the road and you put your hand out the window and you feel that pressure.

00;14;38;16 - 00;14;49;22
Andy Richardson
Yeah. So that's like the velocity pressure. It's it doesn't I say that example, but it really doesn't actually exist anywhere because the pressure really doesn't happen until it hits something.

00;14;49;22 - 00;14;50;12
Jay Fraser
Yeah.

00;14;50;15 - 00;15;23;09
Andy Richardson
So but it's sort of a theoretical pressure. And so of that theoretical pressure. What percentage. A lot of it is based on percentage. So the, the internal pressure is 5.55 plus or minus. And so I think about like a soccer ball. So it's, it's pressing on that like 55% of that velocity pressure let's say 30 SF. So if it was 30 SF then half of that is pressing either on the soccer ball for pressing it from the inside out or it's sucking it in, right.

00;15;23;09 - 00;15;49;23
Andy Richardson
So it could be one or the other. So if it's pressing on at 55%, and then on top of that you have another, pounds per square foot, 55%. Well, that's going to be the full 100% of the 30. So that's going up. So uplift is created through that positive pressure. And then the negative pressure on the on the top of the roof, which is like creating an airplane wing.

00;15;49;25 - 00;15;50;27
Andy Richardson
I don't know if that helps at all.

00;15;50;27 - 00;15;51;13
Jay Fraser
But it does.

00;15;51;19 - 00;16;14;01
Andy Richardson
Yeah. So you have I like the soccer ball analogy because the internal pressure really doesn't affect the main when force pressure of the building like the lateral, because what happens is this. But the soccer ball analogy as an example, it doesn't matter if it's if it's a 100 SF or 50 SF, that soccer balls standing still. Yeah, because it's got internal pressure.

00;16;14;04 - 00;16;27;25
Andy Richardson
But when I put external pressure on it, that's what makes the ball move left or right. So that's kind of an analogy of internal pressure versus external pressure. External pressure on that ball would be like the the wind blowing over the ball and doing something to it.

00;16;27;25 - 00;16;28;24
Jay Fraser
Or foot.

00;16;28;26 - 00;16;45;27
Andy Richardson
Yeah. Or a foot kicking it. So so that's I guess a primer on internal pressure and a closure, partially enclosed would be the typical example of like the big box store enclosed would be a typical house. It's pretty balanced.

00;16;45;27 - 00;16;46;23
Jay Fraser
Yeah.

00;16;46;25 - 00;17;09;13
Andy Richardson
Or a building that's pretty balanced in terms of windows and doors and what the idea is that the windows are going to break because of impact. And this'll even though that is another factor because, you know, now they're requiring us to protect all the windows. And if it's play impact glazing, technically it's not considered an opening for wind.

00;17;09;13 - 00;17;33;09
Andy Richardson
Right. So that takes that window out of the equation like the literal equation for enclosure. So it's like it's not even there. So that's one way to eliminate the partially enclosed aspect. But yeah, it definitely increases the internal pressure, which kind of blows the building up theoretically from the inside out. But it's something we just designed for.

00;17;33;11 - 00;17;35;14
Andy Richardson
So I don't know if that helps.

00;17;35;17 - 00;17;54;02
Jay Fraser
I have for just general code, design criteria question. Yeah. What artificial intelligence have you found as the best one to quickly find needles and haystacks when you're looking for codes? I've tried some. Well, I think it's getting you there, but it's. They get it wrong a lot.

00;17;54;03 - 00;18;02;17
Andy Richardson
Yeah. ChatGPT hasn't been a good, good one for me on the code aspect. It's been okay. Yeah. I've found perplexity. Maybe a little better.

00;18;02;17 - 00;18;02;28
Jay Fraser
Okay.

00;18;03;04 - 00;18;04;27
Andy Richardson
I don't know if you've tried that one out.

00;18;04;29 - 00;18;08;02
Jay Fraser
So that take away from this so perplexity.

00;18;08;02 - 00;18;24;20
Andy Richardson
Now I will say my, my trick of the trade is, well, I would not, you know, use it to design a building, that's for sure. And and I found that to be like I've done to I've got a quiz I do with my, new hires and one of them is like a simple beam calculation, and I.

00;18;24;22 - 00;18;46;02
Andy Richardson
So I know the response, the answers to it, because I've sent it out so many times and I had ChatGPT do it, and it actually got it wrong. And it's a simple equation in my opinion. Three, three basic questions. So I wouldn't do any calcs with it. Yeah, okay. It's not ready for that. But as far as finding a code provision, it's very efficient at that.

00;18;46;02 - 00;19;09;29
Andy Richardson
And you can always go to that code section yourself in Ascii or whatever and do the the research, you know yourself or whatever and know like for example, I was doing a little project at my house and I just said, you know, what is the handrail requirements for? Yeah. For like and it said, you know, I don't remember it offhand, but it gave me the height of the handrail and the spacing, and I was able to pull all that up.

00;19;09;29 - 00;19;19;29
Andy Richardson
And then I told it and by the way, provide me the, you know, the links to validate that. So that's the trick is tell it to provide you some links or some validation references.

00;19;19;29 - 00;19;34;13
Jay Fraser
So it gets I feel like I guess ChatGPT really gets ABC and IRC mixed up and and and picks and chooses whatever version and and gets the versions mixed up. Because you said earlier it's changing every three years.

00;19;34;16 - 00;19;40;12
Andy Richardson
Yeah. So those are a couple things I've, I've learned. Any other, structural questions. No.

00;19;40;12 - 00;19;41;25
Jay Fraser
That was my one for you today.

00;19;41;25 - 00;19;52;09
Andy Richardson
So, yeah, maybe I could come over and and do a lunch and learn with you guys, if you like, and go over some more things. I love that. Okay. All right. Thanks, Jay. Again. Take care. Appreciate.

00;19;52;09 - 00;20;01;21
Madeline Richardson
Hey everybody, thanks for listening to today's episode of enhance and please me like a subscribe or follow and we'll see you next time.