Shear wall design

[farooqbro]

AOA 

i am facing problems in shear wall design .what are the pier and spandral ?what will be the difference when we assign pier or spandral? without assigning these the shear wall design is incomplete .

i am taking about etabsv16

someone have document about shear wall design plz provide it 

thank you

 

[Waqas Haider]

Last month, i design a structure with shear walls. I will attach more documents. What i know/remember i will share with you.

In simple, Pier is similar to column and Spandrel is similar to beam. Shear wall is modeled in etabs as shell element. You are to assign it either pier label or spandrel label (Depending on situation of shear wall) to design a shear wall. If you want to design a shear wall, it mostly needs peir label to be assigned. But for the portions of shear wall above openings, as its behavior is somewhat like beam resting on two supports, you need to assign it a spandrel label. I have attached screen shots of my model where you can see i have assigned pier label to the vertical elements and i have assigned spandrel labels to the elements spaning horizontally above openings. The reason behind is detailing based. The detailing in vertical elements of shear wall is similar to wall (or column) and its design is based on considering it as an element resisting majorly AXIAL FORCES +  MOMENTS along with inplane shear forces. (Theoratically it acts as a cantilever beam spaning vertically which again represent behavoiur similar to column). I have also attached screen shot of design detail of pier which reports total vertical steel in wall with respect to section area for resisting moments, horizontal steel for resisting shear and some times boundry elemtns (i.e. special detailing at ends of shear wall exactly as in column i.e. shear rings confining vertical bars). I have also attached screen shot of design detail of spanderal which reports top steel, bottom steel, to resist moments similar to beam and vertical steel to resist shear along with DIAGONAL reinforcement some times needed to account for reversal of forces.

I will attach more documents throwing detailed light on shear wall design i found few weeks ago. Also my model is attached (it is in seismic zone 4 from where you can get idea about pier labeling and spanderal labeling)

One important thing is that, pier label and spanderal label also meant to integrate forces. i.e. if you assign same pier label to all walls in a floor connected with each other, the software will report results only for one and critical wall because all walls were assigned only one pier label. If you want to have multiple outputs at multiple walls, you should assign them different pier label.

in image number 5, note that i have not assigned any pier to the selected portion of wall. hence no reporting of results is done.

 

Etabs Center Portion.e2k

[farooqbro]

thank you so much for providing informative stuff. 

 

 

 

[farooqbro]

waqas one thing more i am working on plaza having shear wall.

so what type of mesh i used for slab and wall 

what is the role of edge constraints?

[Arash Pursadrullah]

thank you for sharing this.

I have question about the box shape wall. shouldn't we assign the same pier to the wall that works together?

i have highlighted them in the attached Pic.  Furthermore, how do you draw this in Section designer considering having different pier label? 

[UmarMakhzumi]

On 2017-06-23 at 4:11 PM, Arash Pursadrullah said:

I have question about the box shape wall. shouldn't we assign the same pier to the wall that works together?

The answer to your question is already in Waqas's posted reply above. However, I will elaborate it further. You can but there are benefits assigning different labels. For the above case, reinforcement would be reported separately for each wall segment which is extremely useful (and more practical) for detailing. Below is suggested Wall Pier and Spandrel Labelling scheme (Source: CSI Wiki).

Wall Pier Labelling Scheme

Wall Spandrel Labelling Scheme

On 2017-06-23 at 4:11 PM, Arash Pursadrullah said:

Furthermore, how do you draw this in Section designer considering having different pier label? 

You can easily draw this in Section Designer. The only catch is that if you are using the "Wall Stack" feature in ETABS, it automatically assigns the same pier label to all walls. To simply things, you can reassign walls new pier labels in that case.

 

On 2017-05-15 at 0:11 AM, farooqbro said:

so what type of mesh i used for slab and wall 

what is the role of edge constraints?

Use a regular mesh and always use edge restraints. The role of edge restraints is that they provide continuity to adjacent edges which is extremely useful for the case where meshing doesn't line up (as it can cause instability issues).

 Thanks.

[muneeb1213]

Hello waqas.. i really appreciate your effort. Can you please put some light on the results window in order to have a clear understandings of interpretation of results....

i have confusion regarding the top steel and bottom steel in flexure results.. which steel is this result talking about ...

thanks

[UmarMakhzumi]

Piers are designed at 2 locations. Top of story and bottom of story.  Also, FYI Etabs assigns pier labels with respect to story level so that is why the same pier label can be repeated on different levels.

Thanks.

[WR1]

On 6/24/2017 at 2:11 AM, Arash Pursadrullah said:

thank you for sharing this.

I have question about the box shape wall. shouldn't we assign the same pier to the wall that works together?

i have highlighted them in the attached Pic.  Furthermore, how do you draw this in Section designer considering having different pier label? 

This is absolutely wrong practice.

1. PIERS

Assign as per option a (See image posted by sir Makhzumi in previous reply)

Why didn't you apply pier to spandrels. Most people do not apply piers labels to spandrels. Give up on that.

Lets talk about this image. The top floor. Piers go horizontal with same number. 2 shells of P3, 2 shells of P2 and 2 shells of S1 should all have been defined as one pier.

Then P2 and P3 slender piers below them should be assigned different pier names separately.

Infact, as flexural deformations are dominant in these slender piers, divide them (mesh) into 4 pieces and assigned different pier to top 2 shells and different to bottom 2 shells (depends on the moment diagram though).

 

2. SPANDRELS

Assign as per option a (See image posted by sir Makhzumi in previous reply)

The spandrel I see in image is a deep beam. Isn't it? L/D < 4? If so, where is the meshing?

If its not a deep beam then apply different spandrel labels to each shell atleast in the middle for postive moment design.

[farooqbro]

we become totaly confuse what to do ? 

rana and waqas

[WR1]

How do I know what is your confusion without you writing it down for me?

[Palash Engr]

On 7/2/2017 at 6:43 PM, muneeb1213 said:

Hello waqas.. i really appreciate your effort. Can you please put some light on the results window in order to have a clear understandings of interpretation of results....

i have confusion regarding the top steel and bottom steel in flexure results.. which steel is this result talking about ...

thanks

 

 

Dear Engineers, please reply this one. Someone please explain the results with detailing. What is 0.0064, 0.0116, 0.840 in^2/ft, 0.801 in^2/ft, 45.000, 45.000 here ????? 

[Ayesha]

Its providing your reinforcement as % of cross section (0.0064 is 0.64%*AG). For example for you need to divide this reinforcement for both wall faces. For shear, you need to provide 0.84 in^2/ft reinforcement / vertical foot on both faces.

Edited May 29, 2018 by Ayesha

[Palash Engr]

On 5/24/2018 at 2:55 PM, Palash Engr said:

 

 

Dear Engineers, please reply this one. Someone please explain the results with detailing. What is 0.0064, 0.0116, 0.840 in^2/ft, 0.801 in^2/ft, 45.000, 45.000 here ????? 

it will be very much appreciable if someone please upload a detail drawing like the following one i did. I think my concept of detailing shear wall section from ETABS result is not correct. 

 

1 , 2 & 3... is anyone is near to correct drawing? 

Edited May 30, 2018 by Palash Engr