 Navel, Mace, Tidwell, Reinhart, Bowman, Mr. Bowman, what have we been working on in the last few days? Bolsheer, I think that's right. You, he says yes, that's wrong, it's obviously no, only an idiot would say yes to a question like that. I can't believe it. And he's, let me go back and change that hundred he made on quiz A. My goodness, what's the right answer? Well, it's not yes. You have no idea what that question even was. You were doomed from the start. You didn't want to be doomed too, huh? All right, we were working on Bolsheer, we were also working on bearing stresses, we're trying to find out how strong a connection is. We had limits due to pulling little plugs of steel parallel to the direction of load in front of the bolt. We had limit states of the plate just crushing. You can close it a little more, you don't have to be so quiet. I mean, I admit I can hardly see you in your camis there, but I hear the boots. We were doing the Bolsheer itself, that's correct. Coontz, Coontz, what did the crushing state of the plate involve? Do you remember what numbers we needed when we wanted to know how, if a plate would crush? Well, yeah, but I mean, you know, there were some numbers in the equation, maybe like a 2.4, nobody would remember that, but you had to multiply something times something to get the area that it was crushed against. That's not easy. Anybody? Yes, sir. Okay, so that's all the numbers that were involved, okay? 2.4 was in there because that's how strong a find it is, and times the diameter of the bolt, times the thickness of the plate, that was crushing in the plate, and then that area would be multiplied by the stress that they would permit you to use, and that was times the ultimate, that's correct. Chung, you remember what the one was for pushing a little plug of steel ahead of the bolt? What influenced its strength? Toborga, did I write Chung down as here, yeah, Toborga not here? Okay. Well, that was a little length of the plug, it was kind of like a clear distance between the hole in the edge of the hole in the edge of the plate for the ones on the end. It was the clear distance between bolts that were back in the interior of the plate, and then again times the thickness of the plate, and that one wasn't times f sub u, it was times what? Because that little plug is in shear rather than being compressed. What did you do to f sub u to turn it into shear? What did you multiply it by? Oh, yeah, you're my kind of guy, 0.6, but that's not right for bolts, is it? Wait a minute, that's right for plates, isn't it? No, no, no, we're still the master of the plates. We're the guys that get the 0.625 on the bolts. So yes. All right, so here's an example problem where we stopped last time. Got a three-eighths by six-inch wide plate, uses a tension member, got a 1.2 times 12, plus 1.6 times 33, load on it, got to be connected to another three-eighths inch plate. So now we're not probably going to have any preferential between which one we use. Going to use three-quarter inch group A bolts, A3060 for both, assume the bearing strength is adequate, okay? Now, you can just tell us that, and we can, and usually do assume that when we start designing bolts, because we want to say, okay, first off let's see what the bolts can take, how many bolts do we need, and we try and lay them out in a pattern and decide if we want three across by nine deep or two across by 18 deep or whatever we want. And all this time we just say, let's assume the bearing stresses are okay. And a lot of times will be. Now, if you put the hole too close to the end of the plate, all of a sudden you'll find that one there isn't working, but you can fix that. You just move the hole a little further away from the end of the plate. And if the bearing stresses then check, well then you're okay. And if they don't check, you can either make them work, you can space the bolts further apart or you can move them further from the end. And if that doesn't work, then that means crushing of the plate's been the problem and you're not going to fix that with anything except making the bolt bigger in diameter or making the plate thicker. Or put more bolts, and it's your choice. That's usually what they do. They work on the bolts first and then they make sure that the bearing stresses are okay. I mentioned before and I kind of re-emphasize, especially for beginners like you and me, it's probably a good idea to calculate all of these limit states and write them down. Sometimes you find it wasn't really necessary, but a lot of times it makes a difference. A lot of times you'll find the shear in the bolt controls on all of them. In this case it didn't happen to. He very carefully put together a case where it didn't. But if you're going to check how much load each of these points can take, that's the pull the plug, shear the plug out, both of them, interior and exterior bolt. Plate crushing would be the same no matter where it is. Shearing a bolt would be the same no matter where the bolt is, interior or exterior. Then you take the smallest of those and then this one happened to have something smaller than the bolt shear. Then you put the numbers down, lay a fee on them and go. So here's the example that he just gave us. There's your 1.212, 1.633, 67 is the load applied. Wants to compute the capacity of one bolt. The capacity of one bolt then he must mean in shear. It's not known whether or not the threads are in the plane or not so you're not conservative, you have no choice. You're going to have to assume it is a X or an N type of connection. Lahog. Yes. That's not fair, well sure it's one of them, yes. I don't think he meant that, I think he just woke up but I'm going to have to take it. Leon, let me straight the question a little more clearly. Is it this? Well that's not going to work, I'm going to say or this. Which one of those is our connection since we don't know if the threads are in the plane or shear or not? Leon, Leon here? That was a waste. Graham, come on. Fulton, which of those is it? Okay, that's a fair thing to do. Was that Fulton? I've got to be sure I checked you off here. Which classmate are you going to dump that load on? On your right or left? To the one on the left, that is where the threads are excluded from the shear plane. You need a better classmate. Ask the guy on the other side, see what he says. In, that's much to see how smart that side is. Left side's always smarter than the right side. These shear planes are not known where they are so you must say they are included in the plane of shear. X means they are not in the plane of shear, they are excluded from the plane of shear. So we're going to be taking the weaker number. In other words, rather than admitting that the shank is not being sheared so the threads are 0.8 of the area, of that area, they put the 0.8 on the permitted stress. So he says 54 kip per inch, I wonder where that came from. I don't know how far back these notes go. Probably one, and here we go, here's one right here. Those are group A bolts. There's group A, there's group A, group B, so it's one of these two people here. These are threads included, these are threads excluded. And so the stress is 372 megapascals are 54 kip per square inch. And that's why it's so good to put a 54 pi d squared over 4 for the shank. So I thought the shank wasn't cut. The 0.8 is in one of those two numbers. Let's check that, 0.8. See here's excluded, multiply that as 0.8. You know, people who really understand what's going on, it's a little confusing. There's a 0.8 in there, but it doesn't seem to be where it ought to be. You think it ought to be on this number. Well, that's not the way they set it up. So we get 23.86 kips per bolt. Nominal, since there's fair amount of variation in those bolts, you're going to have to multiply it times the resistance factor. That's that much per bolt. And the total number of bolts you need to hold this much load, kips. The units work out nicely. It's about about 17.9 kips per bolt. Kips cancels kips, leaves you with four bolts. So it says use 4 3 quarter inch diameter bolts. You didn't say which pattern. This is as good as any. You obviously, once you put that, that tear line across there, you pretty well hurt a 30 foot long piece of steel. So you might decide to do it this way. Have a little smaller plate. Put the bolts like that. Can only get away with that so long when the number of bolts is equal to the length of the bar, well then that's not good. Mitchell? Not here? Dang. Okay, well I was waiting for Mitchell's here, but that's okay. Mitchell, what is the permitted stress for a group B bolt period? I'll give you a hint. And that's okay, see, but you are looking at the stress, but this table's also for tensile stress. We'll get into that later. You need to be over in the sheer people. And the allowed stress is? No, not for that question. What is the permitted stress for a 490 bolt? I want you to think, 68 is the right answer because I didn't tell you which way it was. And you say that's really rotten. That's right, I love it. Okay, what in the dickens an available sheer strength of bolts? I don't know what that's for. Let's just see something. We know one of the numbers here. We know that the strength of a three-quarter inch group A bolt in type is three-quarter is including the fee, 17.9 kips per bolt, three-quarter inch bolt group A end, three-quarter inch bolt group A, excluded, included, single shear, double shear. Wow, look at that. We've got tables for this stuff. If I know how strong the bolt is in sheer, just pull it right out of the table. Group B, I think that we had some questions on a Group B. I asked him a question on Group B just to get him out of his comfort zone. And the only reason I say we were doing Group A on the example problem is I copied it down from the previous page just so we would know why we were on this page, what was going on. Zepeda, what is the strength of a Group B seven-eighth inch diameter and double shear? What is the strength of a Group B seven-eighth inch diameter and double shear? Group B, I didn't tell him which, so he has no choice but to take included. He had to go to the seven-eighths and double shear. He's right, 61.3 kips. That's correct. That's how strong those bolts are. Here's the larger bolts down here, one and an eighth, one and three-eighths, one and a half. That's a good table. Down at the bottom, you'll notice they tell you what the LRFD resistance factor that they're using in this table. So there's no doubt about what he's doing. Installation of high strength bolts. These high strength bolts will enable you to put so much tension in the bolt that the friction really will just carry, that the friction will carry the load right through the plates if you tighten them up tight enough. Now if you just tighten them to a snug fit condition that's acceptable in many connections, especially in a slip critical connection where you don't want the joint to slip, then you have to really ratchet them down. If you do that, you can count on these two pieces never moving with respect to each other. That may not matter to you like in a building where these large loads only come once or twice in a lifetime, probably never. Probably almost never from the forward direction and then the backward direction, but in bridges and things and some structures, you get a load back and forth, a repetitive load. And if you just make this what they call a bearing type connection where when you pull on this real hard, this bolt, this plate bears up against that plate, one time that's not a problem. And that'll pull this bolt over so that this plate bears against this side of the bolt. But two times, okay, 50 times, that's okay. 1,000 times, 200 times a day. Well, there's some structures that's probably not gonna be a good idea because then it will fatigue the bolt. So we would specify a slip critical connection and that's one where you ratchet this thing down so tightly, we'll make you do it so tightly, we'll just make you use more bolts until this thing just won't slip. You'll have to know the coefficient of friction so that you can get that done. A total friction available to you, in this case, you put the bolt in. If you split out the top half and look at it, you know there is a tension in the bolt. They require you to draw these bolts up to a minimum tension if you're going to play this game. And that tension force due to equilibrium would be this normal pressure between these two plates. Probably isn't distributed uniformly in a circular fashion out to 3.2 inches. You know, it probably is low out in here and high in there, right around the bolt. But it really doesn't care when friction's concerned whether you distributed this triangularly, that total normal force, pressure, or if you did it uniformly like he has shown, you still get the total force between the two sliding planes, times the coefficient of friction to keep these two from slipping. Putting that force in here, putting the tension in the bolt, is going to elongate the bolt, PL over AE. So since you know how these bolts are threaded, you know how many threads there are per inch, we could probably relate how many times you have to turn the nut to put this much stretch in the bolt so you would get this much load in the bolt. And so I could probably tell you how many cranks on the nut you need to do to get a specified pre-tension in the bolt. And they do. With no external loads, of course you obviously have nothing but the pressure between the plates. When you put this external P load on there, then the load P is resisted by the friction force. It doesn't even go through the bolt. The bolt doesn't even know you did anything. In other words, you crank the bolt down and you put enough tension in it and he's screaming and he's, oh, wow, man, bummer. But then when you put the load on the plate, he says, I said, what happened? He says, I don't know, you hurt me. No, I mean, what just happened? He says, nothing. The load goes right through these two plates in friction. When now then you went above my slip critical number and now then the thing starts in bearing. And if that ever happens, then I gotta have a backup. And the backup I'm gonna make you do is when you design this slip critical number, you're gonna make sure that if it ever does slip for some reason, it still can be handled and the bearing stresses will not be excessive, shearing the bolt won't be excessive, crushing bearing stresses won't be excessive. You'll still have to make sure it does all of that. It's just that, and if that ever happens, then what happens is this thing will start banging into the bolt and some of them will start to fatigue. And we inspect these things regularly. Joe will get on his little radio and he'll say, hey, Sally. And she'll say, yeah, there's only 19 bolts in this joint. I said, how many are in all the rest? 24. Are you sure? Pretty sure there's a hole here with nothing in it. Yeah, I think that's fatigued out. All right, let me bring you some bolts and we'll stick them in there. Or he'll say, there's only three bolts in this thing here. And she'll say, hang on and you'll see her out there putting the things, blocking off the bridge. But he's not gonna fail, we won't let it. Combination of knowing what we're doing and inspection, maintenance. Minimum bolt pretension, these are the numbers to which you can reach. I don't remember which one, it was 90, there's 90 ksi, that's 0.7 times 3, 19.3. Must've been this one here. Must've been a A325 bolt. They make you bring them up to a minimum of 0.7 times the full tensile strength and then they're fully pretensioned. This is your metric table. How we get the bolts pretensioned properly. First we have what they call a turn of the nut method. You know, you can look on that table that I gave you earlier, it came from another book. Told you the shank area of a bolt. Told you the root area of a bolt. Told you the root plus one thread area of a bolt. It'll also tell you how many threads there are per inch. So one rotation of the nut's gonna draw this bolt one thread out. One more thread will be exposed at the bottom of the nut. First off, you make it snug tight and then you go ahead and from that point you start counting how many rotations you need to elongate the bolt. It's not only a matter of elongate the bolt, it's a matter of elongating the threaded part of the bolt and elongating the little bit of shank that's left in the bolt plus the steel is pulling down inside of the head and inside of the nut and these parts are compressing and getting shorter. I mean, there's a lot going on there. The easiest way to find out how many turns to do on one of these things is to put a strain gauge inside there and turn the nut till you get the right tension in there and then you tell everybody else for an A325 3 quarter inch diameter bolt of a certain length you need to put this many turns on it and you'll get the right load in the bolt. But it's basically, theoretically, Delta's equal to PL over AE. For any size, tight bolt, number of turns of the nut required to give a given tension force could be computed, table eight two gives the required nut rotation. I had forgotten that was in there and I went elsewhere for my information. Went to a bolt person. Mr. Bolt person says that if you have a one inch diameter bolt that's up to four D long, four diameters long requires one and a third of a turn. That would be two of the, well I think there's a picture on the next page that shows you. If it's between four D and eight D, somewhere around in there, need a half a turn. If it is longer than it's obviously more flexible and more stretchy, you need two thirds of a turn. So, well you snug it up first from snug tight and here's snug tight definition. The tightness is required to bring the plies into firm contact, typically obtained with a few impacts of an impact wrench or the full effort of an iron worker using an ordinary spud wrench. So, you get some little old guy out there with a sling on one arm. You've got to go get somebody else. He's no longer defined as an iron worker. Here's the picture of it. They show the person what to do. You go out there and you make it snug tight then you put a mark across the bolt and the nut at a corner and out on the plate. And here's a third of a turn, two thirds of a turn. No, that's a third of a turn. That's two thirds of a turn, that'd be a complete turn. Then they tell you how much load you're gonna get in here and some plus five percents. You always get a little more than you think. They've measured it so many times and they know almost exactly what the average over what you were told to put in it that you're gonna get so much so that they actually let you count that you're gonna get more. Next, you're gonna have a calibrated wrench. You've probably seen torque wrenches that you put all the stuff on there and you pull on the torque wrench and it gets to a preset torque that you set on the wrench and it goes pop. You can hear it click and you let go or it'll have a dial gauge on it telling you how much torque you put on there. The torque is to some extent related to the tension force in the bolt but of course there's friction on the threads and all kinds of other things. So what they probably have you do is they'll have you go take your torque wrench, they'll go take the bolt like right here, they'll put it inside of a testing machine and these will be static, there'll be a space there usually and you'll put the bolt in there, put the nut on the bottom of it. These two can't be moved, they're just immovable and as you crank up on the bolt, put a torque on the bolt, these two plates pull in a little bit and when you reach the right torque, it'll be measured. In other words, it'll tell you that you have put this much force it's just like a testing machine out in the lab. They make you do that every day before you start, go check your wrench. Then you know if it's got a dial on it, you know where you're supposed to be tightening these things down. You gotta twist off type bolts, I'll show you some of those. They got a little spline tip on the end of them and you stick a special wrench on there and the wrench cranks clockwise. I don't think it actually cranks at all, it just holds against the spline and then the outside nut is driven and first thing you know, the little tip breaks off, you're there. Direct tension indicators are little washers, I think I showed you some of those earlier, they have little protrusions on them, they stick out and when you crunch them back down from whence they came, the holes they were pushed out of, you can tell with a feeder gauge that you have reached the right tension in the bolt. They got some pictures of all that stuff. This is the spec, we've been talking about it, just now it's time I figured I'd throw in the page. J3 bolts and threaded parts, here's your high strength, here's your group A and your group B, bearing type connections, blah blah blah, snug type condition defined as, they just say into firm contact, it's considered to be the big guy with a spud wrench. All high strength bolts specified, shall be tied to a bolt tension, not less than given in these tables, we already looked at those tables. Any of the following means, direct tension indicator, twist off, so on. There was Nucor's opinion of how many turns they make them. Here's how they start out, blank a steel, get it in a machine, whack it on the head, make a head out of it. Then you see this one's longer than that one, so it has not been ground down, it's been put in something that squeezed the steel out to put a smaller dimension, there's your shank, your radius will go and your threads will go on that. Another view, another view, these are gonna be A325 bolts. That's how they tell them, got A325 on the head. Here they've done a shear on the head, stick it in there and they whack it with a thing that's got six sides on it and it just knocks these corners off. You can see where it's sheared it here. They'll clean all that up later and they also cam through the bottom so when you put it down to be, to stick it in a nut, it's easier to get the nut on. A325s, now I thought it was fascinating the first time I ever saw it. I don't know, I just always thought they stuck it, stuck a V thing in there and turned the nut and went eh, but too slow. The way they do it is they'll take one of these blocks, it's clamped to the base, they take one of these and turn it upside down so they both run the same way but one is off by half a thread and they just mash the bolt and they put just this on the top and just that on the bottom and then they take these two things and they go and the bolt goes drops out, drops out, drops out, drops out. Really nifty. And so they actually are forming these threads, they're not cutting them. That of course is better for the bolt too. It makes it stronger than having a cutting to marks down in the bottom. There's the tip, it's got a spline on it. I got some better pictures. Here, you'll notice this one has a regular washer on it because they're gonna determine the tension by this. This one has the direct tension indicator, they call it. The little protrusions, that washer used to look just like that one and they hit it with something that pushed these little things out of the washer. There's a hole behind them. They look kinda like this. You put the bolt in there. Right now, the feeler gauge just kinda flops around. You screw it down and push this thing back into the hole, the right amount. You can just barely get a feeler gauge between there, you know, that's through. A spline, here it is, it looks like this. Looks like this from the top, kinda like so. So if you put a wrench down on it like that, the wrench has that hole in it. So when you put it on there, it locks it on there rotationally, but it's still free to move in and out. So you can take this tool and you can fit it over this. And then your tool with your handle on it locks on this spline and outside here you have a motor connected to this and the motor rolls the nut in this direction. These are bearings and when the motor is so powerful that this thing is driven up and there's so much tension in the bolt, this thing breaks and that's a carefully controlled dimension right across here. And the minute it breaks, this little machine here, this thing, this wrench, it quits because it knows that it stopped because otherwise it would be like an alligator. It would roll the arm off. Well, if it doesn't break every time then I guess the wrench stalls out. Yeah, that's what they're designed. That's right, they do this very carefully. In other words, every bolt that you buy like this, when this thing breaks off, you have the right tension in that bolt. Now the nice thing about this kind, unlike the turn of the nut, the turn of the nut, you gotta know how long, about how long the bolt is because it takes different terms of the nut. This thing doesn't know whether it's one inch long or 14 inches long until you get the right torque to cause the right tension in a short or a long bolt, this thing won't break off. And when it breaks off, you have the same tension in a short bolt or in a long bolt. How are you gonna take it out? Oh, it's still got the nuts on both ends. Well, no, this is called a button head. The nice thing about them is they don't stick out as far. They're easy, you know, just drop them in. Now the reason this one's got a head on both ends was when you were cranking this around, the bolt may wanna turn. And so you gotta have somebody with a wrench on this end. Maybe not, you know, maybe some of them will be sticky enough that they won't go, but you played that game before, you know, you were trying to tighten something up it wouldn't tighten cause this end was rotating. I'm gonna have to have a head on this end. This one I don't need a head on this end because this thing here is not gonna let this whole thing turn. There's a better view of the direct tension indicator. You see them sticking up there? Should have got a shot on the backside of it. These are called squirters. They have dye or ink or something like that in here when you put them on the plate, face down, then when you tighten up the bolt, when you've reached the right tension, they go, and you can see. So it's easy to inspect. I can go up there and see if they're all done properly or not. When I see a whole bunch of them don't have this hanging out, I say, who did this? Joe says, the guy who's no longer with us. I said, we'll get somebody out with a wrench, let's finish these off. There's a bolt that's been worked in double shear. I can't imagine what the plates must look like cause the bolts are so much stronger than the plates they must have really been messed up to get that much deformation in them. You see the threads have been mashed down and the threads have been mashed down. These threads are undamaged. How come I knew it was in double shear? That's a spud wrench. Those are spud wrenches. What's this for? Shackles, okay, I could go along with that. A more common use. You gotta stick it in there here, I guess, yeah? Well, I think mostly they use this for when the pieces of steel are coming up. The holes aren't lined up, so they'll just stick this in there and bring the other one up until they get it on there and then they wobble it around until all the holes are lined up with each other. Then they leave that there and they stick a bolt somewhere else. That's a drift pin. I remember the name. Is that what they call it? A drift pin? Looks a little long. I guess they say maybe you're right. Maybe that is the name. Yeah, let me write that down like I knew that. Oh, without it. Okay, all right. The spud wrench, I know that. There's a better view of one of them. It's got the spline on the end of it. I think they mostly always have a button head because you save money because you don't need the hacks on the other end and you certainly save a lot of space. Well, we always have torches and cut it off. Got me, you know, once they're in there, I don't think you ever want to take them off. Okay, here's the wrench. It shows torque in both directions and of course it does put torque in both directions but this one's part of the gun, a part of the wrench and then this part rolls with respect to the wrench. There's an advertising view. I don't think I've ever seen any of them. They're that pretty. Dimensions. Notice this one has this with a head. So here was a guy I said, okay, we couldn't get those other ones off, let's buy them with a head. And here's the wrench with which they use. See the motor? It's driving through gears this outside piece. See the teeth that are good for the nut and you can't see down in there the teeth for the spline. Yes, sir, in this case, my guess is probably all electric rather than pneumatic. It's a lot easier to haul around a wire than it is air hose, yeah. And I don't know, I don't know how big they get but on offshore I don't know what they use. Could just certainly could be. All right, so back to slip critical bearing type connections, slip critical or bearing type two types, slip critical is one in which slippage is permitted. No permit, no, which no slippage is permitted, slip critical, still gonna have to be designed as a bearing type connection also. The last thing you need is to have it slip and then you don't have the backup of it still working as a bearing type connection. So even though it's a slip critical connection, it has to work both ways. In a bearing type connection, of course, you don't need to worry about the slip because it's probably in a building where this building has been loaded, who knows, a couple of times in its life maybe some things slipped and banged up against the edge of the hole. Tigger the fasteners become critical, it's why you come up with slip critical. A307s are only permitted in bearing type connections. Gonna have to have either A325 or A whatever, 99 and 490 before you're gonna be able to get enough tension in the bolt to get a slip critical connection. This is how strong your bolt is, nominally, as we said, the force that's gonna be available to you will be a friction force only. And therefore you need to know how much tension is in the bolt. So the tension in the bolt times the coefficient of friction will be how much nominal loads you get per one bolt. And most of the tables and everything that's called little r, sub nominal and little r sub u for a single bolt. That number is modified by the fact that they have found that you always, without exception, give them more tension in the bolt than the minimum required. That number happens to be 1.13. And a lot of testing and a lot of bolts too and a lot of practical applications to get that down to two decimals. So you get 1.13 times the tension in the bolt. H sub f is a filler problem. Sometimes you say, you know, this just isn't gonna fit real well. I don't know if we're gonna use this or that. And it's gonna be really hard to get it in there if that plate is just nicely on top of that. So I'm gonna put in some shims or some fillers. If you only have one filler, they'll probably leave you alone. But sometimes you just don't know that close when this thing is welded and after you get it out there. So you may need several shims. You have several shims we found that you don't get as much friction as you thought. There's too many ways this thing can slip. If you're willing to take those shims back here and bolt them on, then I'm okay. Then they won't slip because they're clamped on to something else. You have one shim, not gonna mess with you. If you have multiple shims, you're gonna have to bolt it down or I'm gonna mess with you. Shim factor is taken from, where's the shim, shim, shim? Filler factor, H sub filler. Gonna tell me about it, okay, maybe later. And then the number of slip planes, obviously if you have this condition, then putting the force on this plate gives you two friction paths through which these slip can be prevented. And therefore a number of slip planes. This coefficient of friction is dependent on the type of surface. Class A surface, one that has clean mill scale. When a lot of rust all over it, I don't want you to grease it on the way out to keep it from rusting, things like that. You can maybe paint it with certain kind of coatings that have been made for this purpose. But if you do that, then we'll call it a Class A surface. Filler factor counts for the presence of filler plates. Sometimes added, different depths shows that the presence can affect the resistance of a connection. Now I'm going from sugui on into the specs. We'll get back to that in a minute. High strength bolt, there's the equation that sugui gave you. Their numbers are, for standard size and short slotted holes, we don't use anything but standard holes. Turn, look at this, you get a resistance factor of 100%. It's that consistent. For oversized holes, we're gonna use them long slotted holes. Here's oversized holes. Here's long slotted holes. You do these in there because once you get this whole thing put together, you're not sure where the bolt holes in the other piece is gonna be. So you just gotta have a little slack, a little room in there to make sure the bolts are going to hold. In case you have worse resistance factors. Coefficient of friction for is the mean slip coefficient for Class A or B surfaces is applicable. For Class A, on unpainted clean mill scale or surfaces with Class A coatings made to do that on blast clean steel or galvanized and roughened, 0.3, which is what we use. Other surfaces can have some higher numbers but you have to prepare them to do though. These of you, 13% higher tension, always when I ask you for a minimum number you always give me a little more to make sure you got there. T to B is the tension fastener that we already discussed. Here's your filler factor. When there's no fillers, there's no fillers. In suggest number of slip planes. More on filler factor. Where bolts have been added to distribute the load in any of your fillers, if you only have one filler between the connected parts, it's a one, if you have two or more, excuse me, that's what I said, where bolts have not been added, if you only have one filler, I'm not gonna mess with you. But if you have two or more and you didn't bolt them down to something, H of F is 0.85. So you just lost 15% of the strength of your connection in slip capacity. No, I think you can make them anything you like. They could be, well you can, but then you got the same problem as you had before. You had the problem is you're not real sure, you knew the guy welded it and he tried to get it out there straight, but he's not sure, did he get hit and banged a little bit? Is it up there like a 16th of an inch? If you bring a two inch block out there and it won't go in there, thanks a lot. Somebody go make another block, we'll have it tomorrow, everybody go home. So probably I'm gonna bring a couple of fat ones and I'll really thin one and I'm gonna mix and match so I get the thing done and go home. Combine tension and slip, bearing strength at the bolt holes. Here's the stuff we've already been doing. So 16.1-127 bearing strength at bolt holes. Here's again the table that tells you the minimum pretension that you must put in a different size bolt for A325 Group A or Group B. Also in metric where bolts have been added to distribute the loads. Well this is Segui's take on what you and I just covered in the specs. So that's worth doing, we'll do that one next time. See you next time. Got a quiz next time? Yes sir. For the quiz, I know you like us to put like where we find our information. Yeah. If we're checking for compactness, is it okay if we just know it, if there's like a footnote, if no... If that is, you checked it. I know you checked it. Sorry, somebody like write that? Well you wouldn't take many words, just say no F or no C. Okay, thank you. Yes sir. Is it okay if I bring you the homework that will be due Friday on Monday since I'm taking the test or it's testing some new? Sure, that's fine. Just write on there like it's supposed to and just hand me initially.