CSI SAFE 2016 Punching Shear Tutorial - Example and Practical Theory

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In this video, we investigate how to analyze a slab for punching shear, how to design rebar and stud rails, and some theory, tips and tricks. Enjoy!
Punching shear manual calculation Canadian code: • Two Way (Punching) She...
Designing a transfer slab in SAFE 2016: • CSI SAFE 2016 - Slab A...
Immediate Concrete Deflections in SAFE: • CSI SAFE 2016 - Reinfo...
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Опубликовано:

11 сен 2024

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Комментарии : 52

@AFMathandEngineering 5 лет назад

Hope you enjoyed the tutorial! Let us know below if you want to see anything specifically! Check the links below: Transfer slab design in SAFE 2016: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-nYe3jisDhXg.html Immediate Concrete Deflections in SAFE 2016: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-ZQiDFYSI-yw.html Manual punching shear calculation based on the Canadian concrete code: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-MEiqcwA9vPE.html

@IrfanShaikh-SE 3 года назад

Please create more videos in detail. I really like your videos

@vasubhadania 9 месяцев назад

I have a doubt.... In ETABS if we have used insertion offsets in column......that joint where base reaction are found for column will not be at the center of column...... Obviously we get moments corresponding to insertion offsets but in point load the size of load remains same as size of column.......now this created some douts as that joint is not at the centre of column....

@walaaeldinmegahed1260 Год назад

Thanks bro. for this valuable video, I have a question .. how can I get the distance between the Rebar Sets , Is it the typical Rebar Spacing?

@genieyas5186 7 месяцев назад

Hello, i have a question please, it is preferable to release colomn or to keep them fixed sincerly

@aquibqadirtunio4090 4 года назад

What is difference between ties and stud reinforcement for punching? Which type is preferred for actual designing and how we have to convert SAFE rebars values into practical drawings

@AFMathandEngineering 4 года назад

Great question, in terms of design stud rails are able to resist a higher stress limit than rebar ties as per Canadian code. In addition, you may only use pin ties in a slab that has thickness of 300mm or greater. So for 200mm residential slabs you can use stud rails for punching shear. In reality rebar is preferable normally as it comes with the regular rebar delivery for the pour. Stud rails need.to be ordered from a separate supplier, are expensive and sometimes end up sticking out of the soffit if not placed correctly. Also guys on site are usually more familiar with rebar than stud rails. You can convert safe values by creating a spreadsheet based on your code and take the punching shear forces from SAFE. This is the preferred method for sure.

@engsam777 9 месяцев назад

I don't want to import slab from etabs, how to I include seismic and wind load in csi safe for slab design

@user-pc4gm7lf7c 3 года назад

What does the first and second number mean by renforce the shear, is it possible for a diagram to show the renforce

@engsam777 Год назад

can you do one with shear walls

@chilotberassagarsamo2340 11 месяцев назад

Can you please explain the meaning of the reinforcement results? how is it interpreted? For example, what does 4x9-10d@100 mean?

@xanzem 4 месяца назад

Stud rails x studs per rail x stud diameter x distance between each stud. Therefore in your example... 4 stud rails with 9 studs each rail, each stud has 10 mm diameter and they are separated 100 mm from each other (between studs), therefore the length of the rail would be 900 mm, you need 4 rails and 36 studs of 10 mm diameter.

@jiaweisun8584 Год назад

Thanks Fred. Btw do you know why sometimes SAFE doesn’t give you punching shear ratio? Says N/C. And sometime when I use punch shear overwrites, it shows N/C for that column I overwrote.

@AFMathandEngineering Год назад

Hey Jiawei, hope all is well! Typically it's when you're trying to model a column with a beam, or a condition where punching isn't applicable. I've seen safe be buggy though and n/c regular columns..I think it's just poorly programmed.

@jiaweisun8584 Год назад

@@AFMathandEngineering Appreciated! Happy Holiday!

@anjankuinkel6844 Год назад

Are we able to incorporate fibres instead of reinforcement while designing slabs in the software?

@AFMathandEngineering Год назад

Fibres are not a suitable substitute for reinforcement in a framed slab.

@sarahfuad4033 3 года назад

Why i have zero reinforcement after design and check ??

@aniliqbal6654 5 лет назад

Very informative. How do you calc. punching shear force. Is it Shear Force?

@AFMathandEngineering 5 лет назад

Thanks! Depending on the column type, the shear force contributing to punching is a combination of the shear force due to gravity load and the unbalanced moment acting on the column. See our punching shear video in the description for more on how to calculate the shear force (not unbalanced moment) by hand.

@d_soulseeker 2 года назад

I got into trouble. My analysis results are not showing punching shear. How to correct it?

@johndfr 2 года назад

you got it?

@d_soulseeker 2 года назад

@@johndfr I remodelled. Then it’s okay.

@mecheil2000 5 лет назад

Many Thanks for this video...really very good... I did many checks for punching on raft foundation with spring support ...i see safe is so much over design ...hope u can share me with some clarification ... as example if I get max reaction from column ...the punching very safe ..but when adding the loads on shell element ( raft ....i see results over design ..why ...i could not understand ...

@AFMathandEngineering 5 лет назад

Yes, I also find that SAFE is extremely conservative with shear reinforcement for deep concrete members, especially things like raft or mat foundations. It will always say you require shear reinforcement even when the mat is clearly thick enough to resist based on plain concrete strength. You have to either use a different analysis program or do some hand calculation given the applied shear force to see if you actually require shear reinforcement or not.

@NTC 5 лет назад

I have a question regarding the drop panels. If I have a drop of irregular shape (and probably not symmetrically positioned at the centroid of the column), how does SAFE determine the punching shear perimeter?

@AFMathandEngineering 5 лет назад

Safe calculates the critical perimeter based on the code you're using, for CSA it will calculate bo from d/2 from the face of the column. If your drop panel intersects the critical perimeter, I'm assuming SAFE will do one of two things: 1. It won't check the column and you'll get an N/C when you're looking at the ratios. 2. It may assume it's a corner or edge column depending on where the perimeter intersects the edge of the drop and analyze it as such.

@NTC 5 лет назад

@@AFMathandEngineering I am not very clear at that point. The whole point of having a drop is to make the shear area bigger, thus more shear capacity. Thus, I think SAFE should check it. But my question is about once there is a drop, the program should also check the punching shear assuming that the shear occurs at the face of the drop too. and in that case, how the punching shear perimeter is defined is not not clear.

@AFMathandEngineering 5 лет назад

@@NTC SAFE is a buggy program sometimes, and isn't the best at recognizing where critical perimeters are always. Like any tool you have to understand what programs are good at and use your judgement with the results. Did you try this case in SAFE yet?

@NTC 5 лет назад

@@AFMathandEngineering yes I've tried a square column drop with an oval shape, SAFE still reported the punching shear perimeter being a square shape

@AFMathandEngineering 5 лет назад

Safe isn't great for irregular cases, knowing the limitations of the program is important Sometimes it's best to calculate by hand especially if you know that the program isn't likely to give you accurate results.

@joserolandomonteza1303 4 года назад

Why i have error n/c?

@AFMathandEngineering 4 года назад

Safe won't check certain columns if they're too close to walls, beams, etc. Sometimes safe auto detects the wrong punching condition (edge, corner, interior) and you have to manually change it. This program require alot of checking and engineering judgement to make sure you're getting the right results.

@mozko0010 Год назад

@@AFMathandEngineering you're true, my strap beam just to close to column. i got my problem solve. many thanks!

@gustavoalvarez1496 4 года назад

how can i check the punching shear for wall footing in safe?

@AFMathandEngineering 4 года назад

Typically you don't check two way shear.in a strip footing, one way shear governs.

@gustavoalvarez1496 4 года назад

@@AFMathandEngineering i gess those calculations have yo be done manually 😅 do You have any video where You explain shear in one direction? Thanks for answering.

@AFMathandEngineering 4 года назад

@@gustavoalvarez1496 Two way shear calculations don't need to be performed at all for strip footings assuming length to width ratio qualifies them as acting one way. We have two videos, check out links below: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-RbV6TWxbcRY.html ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-TCjNMcX92NI.html Please like and subscribe!

@gustavoalvarez1496 4 года назад

@@AFMathandEngineering i meant the one direction shear calculations have to be checked manually.

@AFMathandEngineering 4 года назад

You could get this information from software, don't necessarily need to hand calculate.

@UnmeshBane 3 года назад

How do I validate the shear force calculated for punching shear??

@AFMathandEngineering 3 года назад

The shear force contribution due to slab load is fairly easy, the geometric tributary area of the support is generally equal to that force (SAFE also takes into account stiffness, so not 100% accurate). The shear force contribution based on any misalignment of supports above and below can be approximated based on geometric distance to the support, although again finite element will probably do a better job at this.

@UnmeshBane 3 года назад

@@AFMathandEngineering for raft slab analysis, the variation of soil pressure would be different over the area and the tributary area calculations for columns not in grid is very difficult, so for that is there any way to do it manually to verify with safe for a small example

@AFMathandEngineering 3 года назад

The geometric tributary calculation of an irregular column grid is easily done on CAD. I agree though in a raft that it's more difficult to validate punching shear due to the soil spring behavior vs a slab.

@AFMathandEngineering 3 года назад

For design purposes a raft can be idealized as an upside down two way slab where the loading is the factored soil pressure based on the loads on the columns and walls. Again you can approximate this geometrically but it's difficult to calculate the factored bearing pressures when the grid is irregular (for a simple shape this is easy).

@UnmeshBane 3 года назад

@@AFMathandEngineering thanks for quick reply

@aniliqbal6654 5 лет назад

how do you apply envelope load case In SAFE?

@AFMathandEngineering 5 лет назад

There are a couple ways to do it, either draw a null beam element where your facade is and apply a line load, you can also create a dummy beam of minimum height and depth allowable by safe and apply a line load to that. Some people don't like using null elements as it can cause errors and problems some times. Both are reasonable options IMO.

@aniliqbal6654 5 лет назад

I try to add new load combination and there is an option for linear and envelope load combination

@AFMathandEngineering 5 лет назад

That's up to your building code what load combinations you want to use. It also depends what safe is assigning your envelope load as (SID, dead, etc.) You're the designer, you have to establish what load combos you want to use and what you're going to assign your facade load as.