The Key to determine Effective Length in PEB Design
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- เผยแพร่เมื่อ 26 ก.ค. 2024
- Determining the effective length of members is one of the most critical steps in PEB design. This video explains the concept of identifying the effective length of members for different PEB components with codal reference.
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While preparing this video, I'd suggest to show the global x,y & z axis along with the PEB Frame. Also show the local axis of column and rafter with their dimensions. Perhaps with a little video editing, this video will be more helpful for the audience.
Agreed and will improvise in my next videos. Valuable feedback yar.
This is really informative, keep it up mate.
Thanks, will do!
Amazing information....very useful...🎉🎉kindly upload more videos regularly please
Surely will
Nice and informative video
Thank u
For the beam the unsupported length is full span or length upto ridge (if there is no column support at ridge)
It is upto the ridge. Considering the slope of the building is not less than 0.5:10.
The apex of ridge node will act like a rigid joint, so the LZ value can be splitted at that location
What if the column is with lacings and battens.. say 5 m high column with lacings ( angles at 45 @ 60 cm spacing)
Do videos on manual design and verification of ETABS and Staad Pro reports
Surely will..
make a video on all design parameters, the video will cover all design aparameters one should know
@cesayantan sure will do
What is the LZ value for truss members ,its node to node distance or support to support distance?
Thats a tricky question...
You can consider the node to node distance as LZ for the truss members. Considering that the top chord or bottom chord will be transported only as an assembly. If it is going to be a fully bolted truss, then care should be taken at the time of transport and erection so that member does not deform due to slenderness..
Sir, suppose we need to design rafter for the PEB building in staad having span 25 m and rafter ridge at 12.5 m, the whole rafter is divided into 4 segment in staad, then what will the Lz value that we need to specify in staad.
@suniljatav1937 The rafter ridge connection is considered as a rigid node and the LZ value for clear span rafter of 25m will be 12.5m.
What about the condition with brick wall ? How we consider the lx ly lz in that. If 1/3 rd of the length is brick wall then side girth of spacing 1 m.
Then the height of brick wall need to be considered as the unsupported length for the minor axis..
What is the ky kz parameters for the tube bracing?
Please show code reference too.
Ky and Kz are the effective length factors. For tube bracings, the end conditions would be pinned at both ends. In that case, Ky and Kz can be taken as 1 for tube bracing.
@@parishithjayan we connect ky&kz= 0.85
@@tgsubramanyaprasanna5023 what would be the codal reference for that? Kz and Ky in STAAD is be used to calculate the slenderness ratio of the member along Major and minor axis correspondingly. The Factors depends on the boundary condition of the member. As per table 11 of IS 800, for pinned pinned condition, the K factor is 1.
@@tgsubramanyaprasanna5023 in case of tube or pipe bracing for vertical planes (walls) you can consider ky&kz as 0.5 even because a gusset plate will come in center which will break the effective length to half. in case of tube or pipe bracing for horizonal planes (roofs) you can consider ky&kz as 0.85 because gussets will come at the ends for connections so the length of the pipe of tube is is not 100%. it is getting reduced say 15% because of gusset.
Please make a brief video on LTB sir..
Sure.. will do..
In columns if we have one half sheeting anf half Block work means what will be the values. Cab you explain
Say for example, if the brickwall height is around 3m, and above cladded, then the unsupported length for the column on the minor axis can be taken as 3 + the distance of first girt (m assuming that the girts will be with flange braces).
And to add on, some of the designers are following an approach of inserting one node at the brick wall level and assign the girt spacing as the unsupported length for the top portion.
Generally I don't support that, since the column is going to behave as a whole.
@@parishithjayan can you give the values of same structure as you said in the video. With 3 m block work and 3 m sheeting. For column Kx, Ky, Kz, Lx, Ly, Lz. So that i can have a clear idea.
Another thing you are telling about Indian code. For American code the Kx, Ky, Kz , Lx, Ly, Lz values are same or different.
Please tell me brother
I think theres a mistake in what you said about ly value. If you need to consider girt or purlin as a support, you need the compression flange to be connected using flange braces. Else you can't consider that advantage. And I believe you don't have to define lz for rafter, since that's a bending member..
I totally agree.. You are right about the flange brace. Thanks for pointing it out.
Without the flange brace, the grits or purlins could not be considered as effective.
Coming next to the rafter portion, where u said we don't require to provide LZ. I don't agree with this as they are not a simple bending member. They are beam-columns which means they have internal axial forces developed within them due to the lateral loads. Without specifying the Lz parameter in STAAD, u can't expect the software to consider the proper length for slenderness ratio calculation.
If u have single rafter piece say for 12m straight without any pieces.. then in that case if u neglect to provide LZ, STAAD will automatically consider the node to node distance as LZ for u. If not and u have say 4 nos of 3m pieces in the rafter, then u need to specify Lz as 12, or otherwise the program will take 3 as the Lz value. hope I made it clear.
If there is no additional nodes in rafter ..means you have only two nodes one at eave and the other at ridge...in that case no need to define lz for rafter. but if there is additional nodes created in the model to connect struts, bracing etc you need define lz
@@alwinrojerbinniv8602 yes totally right.. we r saying it is not required to define for the frst case because, the default value for Lz Ly Lx are the node to node distances, if they are not specified. We r taking that advantage and leaving it unassigned..
Sir, any online course on PEB
So far, I didn't make any online course. Will let u guys know if I make one.. Thank u for ur interest.
Sir, For column the kz value considered is 2. But the column is pinned at the bottom and also gets lateral supports from connected members at the top. So it’s pinned at the top also. So kz value is 1.
It's not pinned at the top Mr. Mathew.
It's actually free to translate at the top. As per the codal provision, the effective length factor for column is 2. Kindly check the desired clause in the code book.
Why we cannot consider the lateral support from connected members at top.
I meant members are connected at the top. So they restrict translation in lateral directions.
@@tominmathew344 No Mr. Mathew, if it is pinned at the top, then it should not translate at all. But in the actual frame upon having the lateral load, we will see the translation there na. Then in that case how could we consider that as a pinned support? If it is pinned, then it should not translate at all.. Hope u understand
The entire column and lateral members will be translating in that condition. If the column independently translates, then it’s not restrained.
sir plz make video in hind
@chetansonkar3601 Truly speaking, I dont know Hindi.