 my turn thank you for coming all 30 of you I don't know why it is you know and prophecy's a less than a hundred percent attendance they fuss at you where's our only when you come to a classroom the guys that came to class why should I fuss at you all right quick review when we had members that were torqued shame shame shame we had different ways of analyzing them if for example you had a roof truss with a channel on the top or a wide flange on the top with the gravity load down on the decking above the flange and all of the gravel and tar stuff like that then you will have this case where the this angle right here is theta and therefore the load is on the beam at an angle theta we have decided to break it up into two components he shows you that the vertical force will be designed into the beam just as always you could pick up the horizontal load and put it and bend it about the weak axis which is relatively new for you but you'd still have to take care of this torsion inside of the beam they use channels all the time that's and that's one of the things they're more commonly used for yes I will see me after class about the applications of when you should use channels and I beams and white flanges and Z shapes here's the way we have decided it's in our best interest and your peers to analyze a case one loaded beam go ahead and design it for strong axis bending take into account lateral torsional buckling or anything else web flange buckling you name it and then take the horizontal load and rather than actually putting a moment on this and trying to design the whole thing just leave the load on the top of the wide flange but only take half of its bending strength about the weak axis actually of course this loads up the T that T pulls over pulls this T with a little bit so you probably get some strength out of there but just taking half of it is on the conservative side for all cases that's the way it's analyzed loading case one analysis case one loading case two where you just put in the load off center but you don't have any weak axis bending per se but you do have some torque P times Z loading case two our best guess on how to analyze case two is just go ahead and design the vertical component of the whole thing the whole load about the strong axis plus go ahead and call that a little T half of a wide flange put the bending moment in effect in this this is what you called P times E was the bending moment you wanted to resist divided by the distance this is H zeroes from the centroid of the flanges it's not the full depth they find is not fair to take but that much force moment divided by moment arm on the T and analyze this T for that force the bottom one of course would be the same that's analysis case two then he talks about when this commonly shows up is in a roof Perlin that's the beams that span between the main trust members across from a trust joist these are also called bar joists they will a lot of times use angles in the top they look like this from the end you've put a pair of angles you wrap this bar bend it bend it bend it bend it you put them all together and you weld this piece right in here it becomes a very efficient and very inexpensive way to hold loads and they're ugly as sin but nobody cares because you can't see them there in the roof a lot of times though the horizontal part of the load is going to be on this beam right here and of course you're already going to design it for the vertical load the horizontal part parallel to the joist really bends this thing seriously about its weak axis and you can't hardly make it from this joist to the next joist so what they do is they'll put in what they call sag rods and they'll put them over this point also but the main purpose is to take this 15 foot channel bent about its weak axis or if it's a tee and make it shorter around the top see if I got any more here we go I got a picture here we go around the top you let each other each of them pull on each other so you put one across there to keep these from bending and then here the sag rod goes all the way down and the sag rod goes all the way down there'll be one of these every maybe 10 feet whatever you can live with this is it looking from the side you have the sag rods over the trust members you'll also have one supporting it in the middle so that when this beam bends it has it supported at the halfway mark or you may put in more than that depending now that makes it a statically indeterminate beam but we know how to do statically indeterminate beam so that's okay but the moments would be far something that's got even if this is the end of the channel you'd have a reaction a reaction and another support so that would be like a indeterminate structure kind of what they look like they you know they they don't make this all one long rod you could try that the people in the Hyde Regency thought about that and didn't do it and had a disaster on the hands because of it but if you use one rod all the way down then you got to take one of these nuts and thread it up here about 30 feet then you got to put the channel and the washers on there then you got to thread that nut up about 30 feet then the next one down you'll have to thread it up 20 feet but that's unacceptable so they'll come in pairs kind of like this a little closer together here's an example he's going to analyze some beams that are bent about both axis of course is how we got in this in the first place finding all the loads he has uniform loads you your 305 prof showed you how to do this leave that to you comes up with some number pounds per square foot that load is going straight down it's going to have to be broken up into two components one perpendicular to the beams one parallel to the roof and bending moments WL squared over 8 it's a moment inside of a simply supported beam here was the beam that wasn't 15 feet long because it was supported by a sag rod about its weak axis I'll leave that to you he cheats and uses tables right out of your hand book so he didn't have to solve for the moments inside of a statically indeterminate structure that was supported on the ends and then another sag rod here you just simply get the book find out how far it is between the end points and the moments are listed like 0.7 WL squared 1.25 WL squared and you just pull the moments right out of the tables right on up to many spans that's if you have concentrated loads this is if you have uniform loads this is if you have two loads inside there is if you have three loads inside there on your page 3-2 12 so just starting from you taking your 305 345 and you have the loads and you found the moments inside of these beams now I come into play you have a strong axis it happened to turn out to be 441 pounds a foot simply supported on the ends had a brace rod going this way but that doesn't help this thing it still got a full 15 foot span between brace points WL squared over 8 there was your W that you got from 345 it's 15 feet long WL squared over 8 is your request about the x-axis your weak axis bending here you had uniform load on it it was seven and a half feet long supported and the WL squared over 8 had a mistake in this book the length was I forget seven and a half feet the request turned out to be one Kipfoot which is a mistake that's not much the 15-sure or the 12-sure controls well this is a strong axis and this would be about the weak axis starting with those two numbers we're going to go see if that beam is adequate now right off the bat he does a number on us he says select a trial shape okay I understand that's what design is unless you got some tables or something that'll handle this stuff you're going to be selecting a trial shape and you're actually going to analyze your proposed design and he says why don't we try a C10 by 15.3 that will handle an unbraced length of seven and a half feet and give us a moment that's 12 but he says no no the one I'm proposing doesn't give you a 12 I say well okay I guess you're going to make it a little bigger than 12 he says yeah he says I'm going to make it 33 what he says well I already tried a whole bunch of them that was around 12 and 14 and 18 and 27 and he says I'll tell you now they don't need to have them work so well how am I supposed to do that he says you're supposed to do the same thing and with experience you won't pick a 12 when you start and it's a bit about the weak axis which is horrible okay in other words I'll get this with experience what are my students supposed to do well they have about same experience you do practically none compared to people who do this for a living he says time to pick a beam you want to tell them the answer and let them pick that beam you know so they don't waste a lot of time and they still get the idea sounds like a plan to me but I can tell you nothing more than this beam happens to work now where he got that from as he was tinkering around in his how much moment will these things carry for different items with an unbraced length of seven and a half and he comes up here with seven and a half and he found a channel right here would work would give him 33 having already been down on a previous page up to about 15 and 20 and 25 and going through all of the work involved and it didn't work he says I'd like you to try this one okay well I like to know how strong it is well I'll tell you how strong it is it is 33 about how strong you can have for the capacity of that shape and take into account lateral torsional buckling of the shape got about 33.2 he says now he must have worked this out using the equations because he sure didn't get that off this figure we you and I just looked at three dash 18 where did he get that from says okay is that a table I don't know either doesn't matter where you get it from okay with me that is okay well that's for a CCB of one and that's what we've got he says since we got a uniform load on this beam you can have a 1.3 times that above what you get in the tables so let me see why would he have an extra 30 percent now here are our values of CCB for simply supported beams and this case it was laterally supported at the midpoint it has a length of the full 15 feet but it's braced there with a sag rod and he says you can have 30 percent bigger than the tables than the graph gives you all right I'll take that this is another page with more drawings on it this is an old old text this is the old text here's has all the same numbers they still do here's where he tried this he says CCB is the one you the tables give you the graphs give you this but you can have more therefore you can have 1.3 times 33 I say well man it sounds like overkill for a 12 he says well the way you get to the weak axis part you'll see so I'm going to be able to have 14 point 42.9 kit feet and it won't laterally torsionally buckle that doesn't say that it won't flange buckle well yes it does because the shape doesn't have a little f-point this doesn't say that the plastic moment will take it that's a good point we've got to check and see what the plastic moment is that's when this table that's when this thing really does a lot of lying when it comes down and says you can have 33 and it won't laterally torsionally buckle and when you take the 33 and you multiply it times 1.3 it comes out in here somewhere way above the plastic moment check that so then I might as well check it while we're here the plastic moment for this shape is 42 43 round 43 something like that these things have 0.75 increments boy that's horrible to try and figure out so you know pick a number so it comes and says from the uniform load table gee I just got the emplastic what what is this uniform load table for C shapes and some kind of a table tells you how strong C's are for various links and things like that probably let's see here here are dimensions for C shapes there's your 10 by 15.3 there's the next page with Z's and section modulus's that's all good stuff there there's one tells you how much maximum total uniform loads you can have here's what he's using out of the table since he's got a channel and since it's got the right stress on it he's going to take a 15.3 and find out how much piece of B m sub p you can have it's 43 that's the plastic moment that's where he's getting the 43 and here's how much sheer capacity it has now where did I get it because I didn't get it from there I got max is equal to I got P sub B m sub plastic is for uniform tables he got what here's where I got it right here I got Z sub X out of the table and to find fee sub B m sub plastic x I took the point nine times the Z times the steel divided by 12 40 42.93 kit feet same as he got however since that since you're proposing 42.9 is the limit for lateral torsional buckling or 43 is the plastic 43 plastic is okay you still take the lower of the two 42 point we already said it's compact this is your xx supply now you're going to do your yy supply this is relatively new it's new in that it's got the same idea except you don't have to do lateral torsional buckling and you have to be careful for deflection or the plastic moment which you can run right on up to the plastic moment unless it gets too much deflection point nine times 36 there's your plastic moment I'm sorry there's your Z for your plastic moment it came from the table where we pull the numbers out of the dimensions table not on that page you go yy axis Z 2.34 for our shape 2.34 gives you 6.3 kit foot of capacity supply remember what you're trying to dig out here you're trying to dig out the strength the capacity the supply about both axes then you need the demand about both axes and I just went ahead and did it he says but since this is this is this over this and that's bigger than that then you got to use the deflection limit I don't get that I really don't I'd say all you got to do is you just do the limit for deflections your reflection equation in the manual incidentally and this number doesn't appear if you're going to use it you better write it down going to be 1.6 times the first yield elastic moment f sub y times that's yield times s sub g that's elastic section modulus excuse me about the y-axis and then of course it also needs a 0.9 0.9 1.6 f sub y s sub y 4.97 went ahead to do the same thing right here thing I did so now we know two numbers we got supplies now what we got to do is we got to figure out what is requested we already figure out some of the request yeah we already have the request those are what we came in the door with we had a request x-axis 12.4 we had a request y-axis of 1.034 so now we're ready to drop them into the interaction equation there's your request 12.4 and 1.034 requests here your supplies your strong axis supply was a 42.9 I can make sure this is back on where you can see it the x-axis supply turned out to be 42.9 the y-axis supply was 4.698 things okay now I says I say it's okay it's not okay something's fishy here that dang thing's got a load on the top flange huh what we're supposed to do for things that got loads on the top flange surely I would have not noticed this for 40 years what do we do when things have loads on the top flange what do we do when things have load on the top flange how do we analyze them give you a hint give you a hint what do you do to the thing when you put the load on it what do you say its strength is a y these are y over 2 okay so now then I'm hoping this was done back here he looky there there's your bending strength that you told me you were gonna get out of a whole wide plant a whole channel or wide flange whatever that system was a channel and you're only gonna take half of its strength that's gonna take care of the fact that you didn't put the load symmetrically on the weak axis bending force and it's okay sheer sheer was we already said point four four one kips per foot the thing was 15 feet long even though it's braced in the middle divided by twos 3.31 kips says you can go to uniform load tables you could also go to this is well you can't go to the z tables I talked about that kind of steel see if we got some you know that's right the uniform load tables were where we got the bending strength for the channel that's the properties of the channel there's the uniform load tables this came out of an old book they look at how they miss marked it showed this and called it that so errors do occur and how strong it is visa visa been 46.7 a little bit bigger than two or three good in sheer questions nothing new that's one reason it's boring till they pay you then of course it's not at all boring all right here are your notes same thing like I said I just don't have my pictures on all of this your book bending strength of other other shapes we don't do we're struggling to keep up with where we're supposed to be anyway now then beam columns is where there's no more problem is before because all they ask you is the axial load we ought to be able to tell me the load in a column the bending moment request about the strong axis where you've had 345 bending moment about a weak axis and you've had 345 then you need to know the capacity of the thing in axial compression you've had that back in the first of this class then you need to know the capacity about the strong axis that's that lateral torsional buckling and all that kind of good stuff and then you need to know the capacity about the weak axis that's the last stuff we did so there's nothing new going on here the only problem with it is that's a lot of stuff a lot of stuff to remember it all comes into play it's like taking a final over everything in the class instead of just the last third or something it is it's challenging mentions that most beams and columns or many can be just designed as a beam or a column because that's so much predominantly what's going on that there's not much else that you need to worry about but some of them in fact many of them are subjected to both bending and axiom at the same time in that case they're called beam columns you can read all the reasons you're doing this we already mentioned the interaction equation if you were going to do axial only you would say that piece of you has to be less than that's request the design piece of C piece of N you can tell me that ratio has to be less than 100% of the strength extracted from the available strength same way if you had all of a sudden added moment about an axis makes sense to assume that you could probably take the in your case dog on those AI those ASD people here a sub piece of you over P of the column fee piece of nominal of the column plus M sub you divided by fee this would be a fee in columns this would be a fee in bending times M sub nominal you would expect that ratio to some of that to be less than 100% and if you had a third axis you'd stick in a third term in its full glory for you and me without the terms that are good for ASD and LRFD this ratio plus that ratio plus that ratio you think it ought to be less than one they think it ought to be because if they find a practical reason where their number can go up to 1.2 and give me a little explanation plus a whole bunch of experimental verification I'm in there and they say well we got a lot of experimental verification we have no idea why I'm in there anyway you know hopefully some year they'll figure out why but until then if you can guarantee me this can run up to 1.2 I'm on it then we propose money for research now sadly it really breaks down into two cases if you have a heavily loaded column that also got a fair amount of bending in it and the amount of capacity you extract in that shape is greater than 20% of the available in compression then they call that a heavily loaded it's a beam column but it's like it's a heavily loaded beam and you have to admit to the full extraction of strength because you put axial load in it but you bring the bending moments in you only have to fess up to eight nights not a lot but it's there the strength is there so good enough I'll take it what happens if it's not heavily loaded what happens if this number is less than 0.2 if you try and extract less than 10% of the axial capacity of the beam out of the mix then it's called a lightly loaded beam column and you don't have to admit to all of it so well wasn't much there in the first places he says you don't want it you don't have to have it but I'm just telling you if you don't have much in the first place you only have to admit to half we will back you up a hundred percent it won't collapse it won't kill anybody and you will have a lighter and a less expensive structure but you do have to admit to all of the capacity being extracted bending strong bending weak those are the generic terms here you're in my terms because I've just not familiar with those I'm familiar I know what piece of you I know what m sub u is I know what m sub r for anybody is it's m sub u for me and m sub something else for the loud stress people that's your question this is what's going to be listed in the book and then the specs and right under it they'll tell you what it is for us and what it is for the allowed stressed people and so you should be okay but if you want to write that down in a book so you don't even look at this one you know everything I know him I know that guy I know that lady I know that dog I know that horse I it's up to you and I got that twice on 302 come he's got it twice have no idea oh that's right he he listed for for you and me then he listed for those people equations are on page 16.173 their equation h11a and h11b so an example okay not gonna do that example okay explain to him kind of why this eight nights and half is probably in there you remember in 305 I don't remember if we still cover this in 305 but they are what they call failure criteria one of them is the maximum shear stress failure criteria one of them the one we very commonly use is a maximum stress criteria once the stress reaches f sub y it's all over some of them are one of them is how much energy they think that the thing really starts to come apart when energy stored in something regardless of how you stressed it reaches some limit that what happens to be this one one half sigma so-and-so so-and-so so-and-so it plots such that and they find this is really true for stealing for some materials and this effect really is there you can put sigma y and then you got to stop sigma yield in one direction but if you put a little stress in the next direction you can do it and you can even put a little more because at this point you haven't yet hit the maximum energy that stored in the piece and so some weird things like that do go on and it's something like that someone who didn't know or here's what here's the maximum stress theory when you reach sigma y you got to quit when you reach sigma y you got to quit and what am I saying now I don't know about in between there but you know the quiz when you have other combinations are you gonna have to give me some stress transformation equations but if you hit sigma y in any plane you got to quit says you really don't have to so into the manual for nothing more than just a reference so you know where all this stuff is and we've already seen it in our book 16 16.173 shows you in terms of everybody's terms predominantly a column predominantly a beam this is the criteria for that breakpoint you find all terms piece of our required strength for LRFD LRFD LRFD LRFD here's for ASD other stuff probably will be back to some of this later because we have no interest in any of it just up till today so here's an example I've got a beam ooh look at that it's got actual loads on it and it's got some horizontal loads on it some bending moments now the bending moment let me check the bending moment right quick I'll have to factor these two loads and then I'll put the factored loads here and that'll cause me a couple of factored reactions and the moment underneath this will be the maximum so it would be a reaction times eight and a half feet that's how much moment we're talking about now the question is how is that person going to orient this beam column my guess is since he's bending the beam he will load it from the side if he wants like this from the about the strong axis he's welcome to put the 25.2 in this direction if he wants to but I think he'd be crazy to bend it about the strong axis with that big load rather than bend it about the about the weak axis for that load rather than the strong axis and so that's what the author assumes and that's what we'll assume we're giving all of the loads dead service 35 live service 99 axial dead service 5 concentrated load on a simply supported beam dead service all these still need to be factored here's the factor for these two axial loads 1.2 dead plus 1.6 live gives us 200.4 that's what you should be showing on your column bending load 1.2 times 5 plus 1.6 times 12 that's 25.2 that's where that 25.2 came from on these pictures M max is PL over 4 this case piece of use 200 we're gonna bend it about its strong axis how's it gonna buckle Terry how's it gonna buckle let me repeat it's going to be bent about its strong axis it's a column or a beam depend on this end spend on the other end gonna buckle strong axis that's a good guess but out of 50 50 you know it could be 50 50 chance it's wrong where how do most acts and most columns buckle about their weak axis that's right now they don't always buckle about the weak axis if you brace them about their weak axis in the middle are twice or three times then they may pop over and have to buckle about their strong axis this guy has no evidence of any that kind of stuff going on it's just hanging out in the air so although the bending is about the x-axis the buckling will occur what did I say although the bending is about the strong axis the buckling will occur about the weak axis so if you were to look at this column right here this is what you see you see a column that looks like this you would see that flange and you would see that flange and it would bend parallel to the web it would deflect parallel to the web it would not you couldn't see it buckle it would buckle out of the page about its weak axis impossible and the reason is you go get me a yardstick and you don't tinker with the middle you can all support the ends you put some load on it and you say well I'm just gonna put enough load till it buckles about the strong axis about 50 times lower than that before you get there it'll go to the side and you'll say stop that and you'll say let's try that again he go you know buckle about the weak axis and he's I'm gonna kick well he'll say something ugly to him and he goes he's gonna buckle about the weak axis because there's less buckling strength for this support system than about the strong axis you can calculate how much load it would take to buckle it about the strong axis but no one but you will have an interest in that number all right now let me tell you a problem you've got here which he said just a minute for now as delivered when you put a load on this thing these things aren't straight I mean they're pretty straight they look straight but you check them out they're not straight that's why you put this thing here on it and I think it covered up a few other sins also but when you gave me the buckling strength the oilers buckling load you put a point eight six six on it dropped it down below oilers or Timoshenko's equation now you're fixed to even make matters worse in this problem you're fixing to put a force on the beam you're gonna kick this thing out I don't know not just maybe two tenths of an inch quarter inch you're gonna kick this sucker out maybe an inch inch and a half depends on how long it is and how big the load is and how strong the beam is the point is that you have an added moment P delta which you took into account you now have a added load P delta see the moment arm P delta that you haven't accounted for but this is the first time you put any horizontal loads on my columns either but plan on it you're not getting away with that you're gonna have to give me a P delta effect if you took that same total load and spread it out into a uniform load that would be a lot easier on the beam would cause it to deflect a lot less this deformation you know I really wish I'd written that down I didn't think about it but and I don't know it off the top of my head the deflection under a concentrated load on the simply supported beam I guarantee it's a whole lot less and I think this one's WL squared over eight no that's for a calorie I don't know I can guarantee you this if that total load is spread out this is a lot smaller than this but in both cases you must account for that that P delta effect we're gonna ignore it in this problem only so here we go I love this text but I sure wish he'd kind of reminded me along the way what in the devil are we doing he tells me what to do from the column load color from the column load tables you know blah blah blah since bending is about the blah blah blah here's what he's doing this is calculating the available axial buckling strength about the yy axis since it's unsupported from top to bottom were it supported in the middle then I would have to study yy axing of yy buckling about something half as long and then strong axis for the full length we've done a lot of that there isn't anything new going on in this stuff so calculating the available axle he says you want you just go straight to the load tables I say sounds like it sounds good it's a w10 by 49 they probably got tables for that 17 foot long about its weak axis means I don't have to correct by finding phony KL so you happen to bring that with me available strength axial compression 50 ksi steel w10 by 49 is right there 17 feet long capacity is 405 405 I says you're bending this thing about the strong axis for heaven's sakes don't go get me a bunch of weak axis numbers unless you really plan on doing something stupid like that putting the load along the 90 degree away from the strong axis okay got you things about the strong axis that that's good that means I get to use those graphs they don't have any of those for a weak axis bending ccb is a one for the graphs so we may get some some extra here I don't know unbracing 17 feet w10 by 49 have to track that rascal down probably what you would do is you would go find a w10 by 49s plastic moment and track it down like that it may be on 10 pages later no actually it's still on this page so we're pretty lucky and 17 feet tells me that that 10 by 49 is not the lightest he says well that's only if you talk about just bending there's no telling if this is the lightest including bending about two axes plus axial I understand that it's got a strength of 197 with a ccb of one right 17 feet 197 that's what he got 197 197 he says for urine conditions what are they say well it was uniformly loaded and it was pinned on the ends he says ccb is 1.32 I said where the hell would you get that from I said if it was me I'd get the moment the quarter plus the moment of the half so it's also 12.5 blah blah blah he says send a figure it is oh I take it back it wasn't uniformly loaded was it had that concentrated load 0.32 that's how much extra moment you get don't forget this may lie to you I'm gonna go take my hundred and ninety-two I'm gonna multiply it times 1.32 and I can have 260 he says you can have six 260 under what conditions I say oh well okay unless that's bigger than the plastic moment he says okay don't forget that there's what is the plastic moment he says you can also get that from the beam design chart you can indeed it's right there to 26.5033 I don't know where he got all that accuracy from and he must have some really sharp eyes says also obtained from the beam design chart I don't believe it he worked it out you know he did so the design moment must be limited to this number here here are the factored loads these of course were given to us there's your request for column capacity was we said 200 we factored these we've got 25.2 maximum moment due to the 25.2 was WL over 4 107 drop it in the magic equation the real question is is this which is this which is this greater than two tenths that's the question that way we know which equation to use so we work out the request over the supply we used 49% of it just in axial that's a column they have a little beam flavor to it but that's a column therefore we have to confess to all of our sins in axial loading request over supply we only have to admit to eight-ninths of our bending moment request there was your WL over 4 over your supply there's your 226 the beam is okay the book probably ought to every now and then have some things that just seriously don't work so you don't think they ought to always work that's what students you know first off think gee the problem didn't work the beam was no good especially on an exam that bothers you a lot shouldn't and half the time you get things that don't work for a while see you next time I'm gonna be gone this afternoon consulting up in Dallas so if you were gonna plan come see me with your exam to discuss it gonna have to wait till Monday about Friday I hope by then you've got it kind of settled thank you no no but I got 305 books coming out my ears with that in it like I say I'm probably not even gonna go back to the office so you know can you get it Monday okay well do you have a 305 text that you know I don't remember I just stole it from someplace is this what you need this page yeah return it yeah just return it later that's not a problem sure thing yes it is that's right see the real the real question is if you use more than 20% of the columns capacity with your load right you we have found that you really have to use the equation PCBU over that full blast but you only need to confess to eight nights of the moment if it's if it's less than 20% you only have to admit to half of the number but in that case you have to admit to 100% of this those those are the two now why it's a break point at point two you know well you just you just you just have to go in well in our case it is but that's just because this is a real column I mean it was out in the corner of the building yeah and it's heavily loaded in axial force and there are some moments coming in on it so side loads those are probably wind loads you know the sheeting on the side transmitted to some kind of a beam that hold the sheets on the side of the building and they come in there in the middle of our column and they put a 25 kip load on the side but it's mostly a column yeah just because of the loads is caring now that same problem if you told me that the numbers they gave you this was 20 it was probably really a beam that was a statically indeterminate beam and it had some axial force in it and that happened to be lightly loaded so when you came down here you took 20 over 40 you don't get about 5% and since that's less than 210 so I'd say that's a beam massive that's correct and which means you've got to admit to 100% of your bending but that little bit of axial that you do have in there you only have to admit to half of it well no that's well I don't know you know all of those gifts all of those constants that lets you raise number from the theory number because you didn't bend as badly as you could or all of those kind of reasons those are really there and this one this only I guess the only difference is your bending strength is really there except the theory is wrong because of your supports that's the Christmas presents you get this the Christmas presents here all the time those you don't multiply times something to increase it because the theories doesn't really apply to your support system I don't think that's answering the question but that's I should have just said yeah and reduced bending or the other way around that's right well hey that never hurts I like that idea let me close this out and I'll be with you in just a second