Jump to content
Structural Engineering Forum Of Pakistan
  • Welcome to SEFP!

    Welcome!

    Welcome to our community forums, full of great discussions about Structural Engineering. Please register to become a part of our thriving group or login if you are already registered.

Recommended Posts

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

 

Share this post


Link to post
Share on other sites

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.

 

1.png

2.png

3.png

4.png

5.png

Etabs Center Portion.e2k

Share this post


Link to post
Share on other sites

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? 

2.png.5a32a3ffe7c32fcd287314f4c054f20e.png

Share this post


Link to post
Share on other sites
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

Figure%201.PNG?version=1&modificationDat

Wall Spandrel Labelling Scheme

image2017-4-11%2011:46:17.png?version=1&

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.

Share this post


Link to post
Share on other sites

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

3.thumb.png.fbfd815bf4b7d3f5e92a2b31408c3c57.png

Share this post


Link to post
Share on other sites
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? 

2.png.5a32a3ffe7c32fcd287314f4c054f20e.png

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.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

  • Our picks

    • Dear All,

      The forum has been updated today with a lot new features.

      You can find the list of all the new improvements by visiting this website.

      Some highlights are:

      1) Improved Search Features


      2) Emoji

      Emoji support is now available in all editors.


      Do check out the link posted above for the complete list.

      One additional announcement that I would like to make is that with reference to last forum update post (read below),  @Rana and @BAZ are forum Admins now. I think it was important to do as it brings more transparency for the forum and also helps spread the responsibility. The forum belongs to the members so it never made sense for one person to be Admin,

      As always, feedback is much appreciated.

      Thanks for taking the time out to read this update.

      Cheers!

       
      • 2 replies
    • Hi guys just to discuss with you my understanding of crack widths in Environmental structures according to ACI. 

       

      ---------------------------

      Normal structures

      ---------------------------

       

      1. ACI 318-95 based on statistical method of Gergely & Lutz 1968 limits Z based on exposure. We are calculating crack widths here. (Normal structures)

       

      2. ACI 318-99 proposed limiting the spacing and removed actually calculating the width and also removed the exposure conditions. For example for beams and one-way slabs s (in) = 540/fs -2.5cc or in other words limiting the fs=0.6fy  (For normal structures)

       

      3. ACI 224R-01 references method 1 and 2 above and 3 european codes.

      The most confusing part is the table in which Nawy suggests 0.1mm crack width for water-tight structures. The whole document is for normal structures except this line. And people are following this line and refer to this document for water tight structures. I mean its just a suggestion and by the way this method 1 is obsolete now since ACI 318-99 (see point 2 above).

       

      ---------------------------

      Water tight structures

      ---------------------------

       

      1. ACI 318-08 states clearly that for watertight structures ACI 350-06 codes should be used. 

       

      2. ACI 224.4R-13 also specifically states that for watertight structures walls in section 7.4, we should use ACI 350-06. 

       

      3. ACI 350-06 for water tight structures does not recommend calculating a number for crack width but rather limiting max steel stress in bars to be 20k ksi or fs=0.33fy for normal conditions.

       

      ---------------------------------------------------------------------------------------------------------

      To sum it up, 

       

      Philosophy of crack width control is not to calculate probable crack widths but to limit the max stress in steel bars.

       

      For normal structures: fs=0.6fy and for water tight structures fs=0.33fy
      • 1 reply
    • Hi

      I want to know the use of diaphragms in etabs. i discus many people who are use etabs but i can't get justified answer about the application of etabs.

      I read the Technical reference  of  Etabs, where they write about Diaphragms. i get two type of diaphragms (plate or shell and joint or beam). 

      My question.

      1. When do i use Shell diaphragms (if floor present ) 

      2.When do i use joint diaphragms ( grade beam level where no slab are provide) 

       

      NB: Diaphragms use to transfer the lateral load to the resisting element ( frame such as column. beam,shear wall) 
      • 2 replies
    • *SEFP Consistent Design*<br style="color:#272a34">*Pile Design*<br style="color:#272a34">*Doc No: 10-00-CD-0005*<br style="color:#272a34">*Date: Nov 21, 2017*<br style="color:#272a34">
       

      This article is intended to cover design of piles using Ultimate Limit State (ULS) method. The use of ULS method is fairly new for geotechnical design (last decade). The method is being used in multiple countries now (Canada, Australia etc). The following items shall be discussed:

      Overview


      Geotechnical Design of Piles (Compression Loads, Tension Loads and Lateral Loads)


      Structural Design of Piles (Covering both Concrete and Steel)


      Connection of Pile with the foundation (Covering both Concrete and Steel)


      Pile Group Settlement


      Things to consider



       

      1. Overview

      Piles provide a suitable load path to transfer super-structure loads to foundation where shallow foundation are not suitable - this can be due to a number of reasons like existing space constraints or suitable soil strata is not present immediately below structure. Other uses can be to meet design requirements like to have reduced settlement etc.

      This article shall cover the use of straight shaft cast-in-place concrete piles and straight shaft driven steel pipe piles. There are a number of additional piles types like belled concrete piles, precast concrete piles, screw / helical steel piles etc but the discussion to choose a suitable pile type is not in the intended scope of this article. The article is intended  to discuss design requirements for straight shaft piles only (both concrete and steel) . The aforementioned topic about pile selection is a very diverse subject and requires a separate discussion on its own.

      Click on the link to read the full article.
       
      • 9 replies
    • I am suppose to design a pile foundation for a machine weighing approximately 50 tons and with an operational loading of 100 tons. 
      I ll appreciate your help in terms of guidance & provision of notes...  
       
      Thank you..
      • 36 replies
    • Material behavior can be idealized as consisting of an 'elastic' domain and a 'plastic' domain. For almost 200 years, structural design has been
      based on an elastic theory which assumes that structures display a linear response throughout their loading history, ignoring the post-yielding
      stage of behavior. Current design practice for reinforced concrete structures is a curious blend of elastic analysis to compute forces and moments, plasticity theory to proportion cross-sections for the moment and axial, load, and empirical mumbo-jumbo to proportion members for shear.

       

      From the book "Design of Concrete Structures with Stress Fields" by A. Muttoni,  J. Schwartz and  B.Thurliman.

       
      • 0 replies
    • 9th International Civil Engineering Conference (ICEC 2017), December 22-23, 2017, Karachi, Pakistan
      Dear Fellow Researchers, Academicians, and research students,

       

      NED University of Engineering & Technology in collaboration with Institution of Engineers Pakistan (IEP) is organizing 9th International Civil Engineering Conference (ICEC 2017) on December 22-23, 2017 at Karachi, Pakistan.

       The congress details are available at its website www.neduet.edu.pk/icec

       Also attached is congress flyer for information and dissemination among your peers.

       Abstracts submission deadline has been extended till October 31, 2017.

      Please click on the link to see the full description.
      • 0 replies
    • AoA all,

      Is it mandatory to do column concreting upto the soffit of the beam in a single pour ?

      What code says about the construction/cold joint location in column ?

      Majority of the contractors are pouring the column concrete upto the soffit of the beam (full height of the column), some contractors leave the column height about 9" to 12" below the beam level and then fill this 9" to 12" column height with the beams & slab concreting. On one site column concreting was stopped at the mid height and the remaining half was filled on the next day.

      Thanks

       

       
      • 5 replies
    • 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

       
      • 10 replies
    • Salam Members,

      Congratulations to Engineers, PEC has become full signatory of Washington Accord, what are the benefits to Pakistani engineers for this agreement. 

       

      Regards   

       

       
      • 3 replies
  • Recently Browsing   0 members

    No registered users viewing this page.

  • Similar Content

    • By Syed Asad Shah
      Please guide me about pier and spenderal labels and what is the function of pier and spederal labels in shear wall? and what are P1 P2 P3 P4 P5 P6 P7 and P8?
       
    • By Eko Juwanto
      Good evening,
      1 have a building with all column 2.5m long and 0.5m width, its better to take it as a Shear wall or as a column? and what the technical reason?
      and whether it significant or not if the beam attach at the both end, what I mean is 1 in the top I at bottom (in plane), zig zag formation due to architectural design, its critical or just simply issue? will the column suffer a great twisting moment?
      Thanks
    • By waqar saleem
      How to draw shear wall in etabs?shear wall behaves like a vertical beam against lateral loading do we define it as area section or as beam?
    • By sara
      How to identify the optimum location of shear wall in high rise building?
    • By mhdhamood
      Dear all
      According to ACI code to acount for global delta design using etabs we perform p-delta analysis but my question is that do we need to design the walls outside etabs or we shall depend only on etabs ?
    • By rummaan17
      Dear all,
      I am trying to design shearwalls through ETABS with temperature load applied over shell. At various location, spandral section fails in Shear due to temperature and piers (sometime in shear, mostly in flexure).  (See Attached Image)

      Certainly all the problem in Shearwalls are due to temperature. I don't want to increase cross section of spandral or pier at some location just due to temperature load case as it will appears non-uniform with rest of the wall. 

      I have seen stiffness modifier affect distribution of forces and also rigid/semi rigid daiphragm assumption. 
       
      Can anybody guide how to properly design the shear wall with temperature load applied in ETABS or share any similar experience. Thanks in Advance.    


    • By BAZ
      Can shear failure of structural walls trigger collapse of reinforced concrete building if the building satisfies drift limits and its frame can independently take 50 percent of seismic force in both directions.
    • By mhdhamood
      Dears;
      do we consider slenderness in designing shear walls , say I have 1.5*0.3 m sectio with height of 6 meters?
    • By batoul
      hello, 
      plz i need help in designing shear wall i want to ask about the reason that some time the shear wall  considered at all like a boundary element it means that the reinforcement along the wall have the same distribution like a boundary element ( transversal and longitudinal reinforcement + vertical reinforcement
    • By Mason
      I need some guidelines regarding design of Shear Wall in ETabs.
      I have attached Design Detail of one of the pier of a 30 story building in Islamabad.
      this pear is at the basement and the analysis is "Dynamic".
      I have a feeling that the flexure reinforcement required is too little for this type of structure.In  most of the cases flexure reinforcement is either controlled by the spacing requirements or the confinement requirements of Boundary Element.
      The analysis is based on UBC-97.
       
      Obj.Docx
  • Recent Discussions

  • Latest Forum and Club Posts

    • Sir's thnakq so much for you reply but are they any structural rectification for this problem . can I give another footing adjacent to the settled column. If so which type of steel structure I can design.
    • Dear all, can any one explain how Etabs calculate joint shear capacity of the RCC structure
    • Could you help me understand how moment will be distributed in two ends of beams if one end of beam is fixed and other end is partially fixed? Say, previous 24ft beam with 15k/ft udl....FEM are -720 k-ft both sides.....now one of end has been partially released so that it can develop 360k-ft how will moment be distributed to other end...I am getting 900 k-ft at fully fixed end and shears at 2 ends became 157.5 and 202.5 kips..., I fail understand how to solve this indeterminate beam with one partial fixed end...   Thanks for your help
    • The settlement is likely due to weakening of soil support beneath the columns. There may be several reasons for this, like ingress of moisture in the underneath soil, sudden subsidence of some underground cavity etc. This may be investigated through some geotech engineer. Underground water tank, some nearby leaking water supply or sewerage line might also be the reason for weakening of the soil. To start with, these should also be checked & any leakage observed should be promptly & properly rectified.  Futher advice can be given on knowing the results of geotechnical investigation, carried out for determining the most likely cause of settlement.
    • Thanks for your reply. Actually your blog was one of the first I studied before doing it. 
      I understood it now. ETABS is using equation like M=(n/(n-1))*4EI/L*theta. so rotational stifness constant k=(n/(n-1))*2EI/L. If you are reducing stiffness on both sides consider using spring constant of (n/(n-1))*2EI/L n=% of moment to be resisted.....for n=1 we will get fully fixed, for n=0 we will get fully hinged.  The graph can be considered to be n(Y-Axis) and (n/(1-n))*2 as X axis. The data makes sense now. i am worried about 3D now, I have 55 story building in which i have to model connection loss in terms of decrease of stiffness. I don't know if I could use 
    • What kind of foundation system is there. you can consult a geotechnical engineer as well to get some option interms of soil improvement etc. From a structural point of view, you can  always introduce more columns and reduce load per existing column to reduce settlement. Thanks. 
    • plz help me out of this problem.. the foundation is settling down week by week. it is a warehouse. a big  Under ground water tank is adjacent to the failed column. we have only little space to work. this is in dubai. Suggestions please what so i can do. plz do reply
    • First, the stiffness of this beam is 2EI/L. See here; http://classes.mst.edu/civeng217/concept/12/03/index.html Second, see the fixed end beam in this link, hope it clarifies. Do share the findings afterwards please. https://waseemrana.com/2013/04/16/how-to-partial-fixity-in-etabs/
    • I am trying to understand how rotational spring constants work in ETABS. I have considered 24ft long beam with 15kips udl applied so that fixed end moment is 720k-ft I assume that spring constant will be function of EI/L. I assumed that ETABS would have linear spring, so that if I find lowest spring constant to give me 720k-ft fixed end moment, I would half that spring constant to give me half restain so that moment will be 260k-ft. In reality results are far from it. the graph attached shows factor which I multiplied to (EI/L) to get spring constant in kip-in/rad in X axis and Y axis shows corresponding end moment/720. Can somebody explain how etabs spring constant work so I find factors representing fraction of total restrain.
    • Did you got the answer of your question?
×

Important Information

By using this site, you agree to our Terms of Use and Guidelines.