Jump to content
  • Announcements

    • UmarMakhzumi

      Eid-ul-Fitr Mubarak   06/25/2017

      Happy Eid-ul-Fitr everyone. May Almighty shower HIS blessings upon you and your family members.
  • 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.

Abdul Malik Memon

Column Placing/Positioning

Recommended Posts

Asalam-o-alaikum,

I'm working on a Ground +3 residential bungalow. The column position  assigned by architect seems quite vague to me and i think that number of columns can be reduced but as I'm an beginner need seniors advice. The attached file is an architect plan.

Furthermore, are there any standards for column placing/positioning? if yes, then what are those?

  After designing a structure what check must be performed before handing over the design results?

And any literature about pick-up beams?

Thank you, hope I haven't flooded the post with question. 

arch jawad drawing.dwg

Share this post


Link to post
Share on other sites
On 6/19/2016 at 6:08 AM, Abdul Malik Memon said:

Furthermore, are there any standards for column placing/positioning? if yes, then what are those?

Nothing specific. There is nothing wrong with having this many columns. These columns are more like confined masonry columns rather than structural columns.

On 6/19/2016 at 6:08 AM, Abdul Malik Memon said:

After designing a structure what check must be performed before handing over the design results?

Sanity checks. Your results should make sense and load path should be complete.

On 6/19/2016 at 6:08 AM, Abdul Malik Memon said:

And any literature about pick-up beams?

Pick-up beams?

 

Share this post


Link to post
Share on other sites

First you must be clear about requirements (arch, mep etc). Have a clear understanding of dwgs, are the cols masonary, non load bearing? Have you prepared 2, 3 different struc schemes? If you think you can value engineer and reduce cols, check with client req if they too want it.

Then you make sure the scheme is working, deflections, load paths, foundations, framing, cost.

Reducing cols mean, bigger beam and slab spans and so more deflections. Have you checked that? Also more local load on foundations if cols are far, and more sway in wind/eq bcz less bending stiffness of vertical elements (if you are not increasing col/wall sizes to compensate that).

If above is okay, you can eliminate cols that are not required. As a struc engr you have to be proactive, pitchin and promote the "most efficient" scheme that is "simple" and "necessary".

Share this post


Link to post
Share on other sites

i have heard about pick-up columns but not beams. i think they are not structural columns but just for architectural purpose or so. If any of the seniors could explain about these two, it would be great.

Share this post


Link to post
Share on other sites

Pickup columns or planted columns are structural cols supported on transfer slabs or beams (which you are referring as pickup beams i think).

For seismic design you have to overdesign collector elements like transfer beams or slabs by omega factor.

Issues with pickup cols is loads in them depend on stiffness of slabs/beams supporting them. If supports are flexible they are literally just hanging threads from slabs above carrying little or no load at all, you cannot just manually transfer loads to them by distributary area. Another thing is to check deflection at upper and below slabs as well as punching on both slabs.

Make sure the transfer slab has sufficient shear strength.

Another issue might be consteuction sequence and long term deflections due to these columns.

Also make sure you check for irregularity clauses of seismic code.

Share this post


Link to post
Share on other sites
On 6/21/2016 at 3:11 AM, Ayesha said:

Pick-up beams?

 

 

On 6/23/2016 at 3:41 PM, Hira Malik said:

i have heard about pick-up columns but not beams. i think they are not structural columns but just for architectural purpose or so. If any of the seniors could explain about these two, it would be great.

sorry means, heavy beams beneath the pick up columns.

Share this post


Link to post
Share on other sites

These columns are like 9"x18" or 9"x21" . at places these are coming into the doors  which should not be actually. if these are to confine masonry then you do not need that much larger sections just 9x12 or 9x9 columns  are enough. if you are proposing a combined frame and masonary or frame only then increased columns sections will be used. make different design proposals and discuss personally some senior near you. 

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

    • Assalam o alaikum.
      According to ACI 12.5.2,
      development length for fc' = 3000, fy=60000, for normal weight concrete and epoxy less reinforcement, The required development length comes out to be
      for #3 = 8.2 inch
      for #4 = 10.95 inch
      for #6 = 16.42 inch
      for #8 = 21.9 inch
       
      And if in my case, ACI 12.5.3 is not fulfilled, it means now i have to provide ldh as mentioned above. ldh is STRAIGHT EMBEDMENT LENGTH + RADIUS OF BEND + ONE BAR DIAMETER as shown in figure attached. Now my question is, if in my case, main reinforcement of beam is of #6 and #4, minimum column size required will be 18 inch and 12 inch respectively. Lets say by any means, i can not select #4, #3 bars and size of column where bars are to be terminated is 12 inch, how to fullfil this development length???
      • 11 replies
    • 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.    
      • 15 replies
    • ENGINEERS;
      I WILL LOOSE MY BRAIN FROM ETABS. 
      I DECIDED TO MAKE MANUAL MESHING FROM AREA ELEMENTS BESIDE EACH OTHER AND EVERY HING WAS FINE .
      BUT AFTER DEVISION SAY 7*7 ELEMNTS FOR EVERY BIG ELEMENT AND MAKING ETABS CHECH..................THEN 500 ERROR MESSAGE THAT ALL ELEMNTS ARE CLOSE TO EACH OTHER.  WHAT ARE GOING...... SOMEONE TELL ME PLEASE...... I WILL LOST MY WORK
      • 6 replies
    • Assalam o alaikum.
      I have just designed a frame structure with SMRF. The out put of shear seams weird to me. Column reports design shear Av/s as 0.045. (Images are attached). but when i right click the member, it must show me the most critical case HIGHLIGHTED AUTOMATICALLY. But it highlights load combo 38 (auto-generated combos have been used) which reports Av/s as 0.038. And 0.045 value is at combo 32. Is their any logic behind it?? More over how to interpret this Av/s?? means 0.045 in kip-in units means what? How can i convert this into spacing?? 
      • 9 replies
    • Hello everyone, I hope all of you will be fine. In etabs when we apply Response Spectrum loading on a multistoried building with 2 basement floors. At what floor level this loading will be applied as in equivalent static seismic analysis, we can apply EQX & EQY on any floor we like as this option is available in etabs but the problem is with response spectrum and time history analysis. please if someone knows and have the experince, share it i shall be very thankful.  
      • 5 replies
    • Salaikom dear professionals,
      First of all I would like to express my sincere thanks to the initiators of this forum for establishing such an exceptional atmosphere for knowledge/experience sharing, I it is really useful, In fact since I have found the forum I am mostly online and busy reading the posts. I would also like to thank the members for their professional comments and advice.
      As my first post in this forum I would like to ask the following queries:
      1-After running the analysis and design when I check the DESIGN DATA through Display >> Show Tables >> DESIGN DATA >> Concrete Frame Output, there is no specific message in Column Summary Data and Beam Summary Data, but in Joint summary data it is showing that “Joint B/C check not done”. Does anyone has any idea? I am sharing the ETABS model for your information and easy reference.
      ETABS MODEL.zip
      2- ETABS provides greater area of steel in the upper column than the column at BASE, perhaps due to higher moment. Could someone explain why this is so? In practice should we maintain maximum steel in both stories? Or we shall follow what the software suggests?
      3- Beside considering the minimum thickness required for deflection control of Beam as per Table 9.a Chapter 9 ACI-318 , using concrete crack behavior in ETABS and checking story drift, Do we have to check the deflection of beams for the serviceability propose elsewhere in ETBAS? If yes, Could anyone explain it?
      Regards, and look forward to any explanation
      • 13 replies
    • Posting this thread to break the ice. Modelling domes is very easy in Etabs/SAP. All you need to do is to draw the curvature of the dome in elevation by a series of straight lines, but draw only the one half. Then using the apex at centre point, radially extrude the line say 24 times at 15 degree intervals (or 48 times at 7.5 deg intervals. This feature is under Edit> Extrude Lines to areas. You can further use this geometry for Finite Element Analaysis.
      • 22 replies
    • Hello,
       
      I am designing the mosque in zone 4 . The roof of the mosque is a Truss.I have following questions 
       
      1. Do truss rest on the beam ? if yes .? do i have to assign any support conditions ? or etab will selelct by default.
      2. what will be the grade of steel for the truss ? yield or tensile strength. some one told me go for A 36 ( 36,58)
      • 15 replies
    • I accidentally came across these useful case studies, which, I would like to share. You can use them if you are working on a commercial or residential building retrofitting project. These case studies provide insight about seismic retrofitting and also on analytical methods, that are used for building assessment. I would also like to give due credit to people who are involved in these studies. All these studies were performed under a US-Pakistani Joint Cooperation Project. The details for the project are.

       





       

      6-Storey Mixed Use Building in Karachi.pdf

      10-Storey Office Building in Karachi.pdf

      RS-4 Storey Academic Building in Karachi.pdf

      Five Storey Residential Apartment.docx

      Please visit the thread to download the attachments.
      • 2 replies
    • *SEFP Consistent Design*
      *Diaphragm Flexibility*
      *Doc No: 10-00-CD-0004*
      *Date: August 07, 2014*
      I am writing this article about a very important, but mostly neglected topic of flexibility of diaphragm. I used to assume that all reinforced concrete slabs can be treated as rigid diaphragms. But as it turns out, only the slab with span-to-depth (depth is length of slab in direction of lateral loads) ratio of less than 3 and without horizontal irregularity can be treated as rigid diaphragm. The more important thing is that the span-to-depth ratio and horizontal irregularity is not the only criteria and one other factor also needs to be kept in mind before assigning rigid diaphragm to concrete slabs in numerical model of building.
      Another important concept that I learned, and it was a moment of epiphany for me, is about TRANSFER diaphragms. I had posted a topic “Amplification Of Forces In Etabs” earlier in this forum but we were not able to reach at a satisfactory conclusion. Now, I have the answer to that query: Back Stay effect. Another article is required to explain it , and this concept is not discussed in this article. This article is about flexibility of diaphragm.
      Diaphragms are horizontal members of the lateral-force resisting system of building structures. Their function is to distribute inertial forces, generated at its own level, as well as other levels, to vertical members of lateral-force resisting system.
      One kind of diaphragm only distributes inertial forces generated at its own level. This kind of behaviour is observed in buildings where there is a continuity of vertical members of lateral-force resisting system: building should not have a setback or podium at lower levels, or below grade levels. The other kind of diaphragm, known as “Transfer diaphragm”,

      Read more: http://www.sepakistan.com/topic/1480-diaphragm-flexibility/

      • 4 replies
  • Recently Browsing   0 members

    No registered users viewing this page.

  • Similar Content

    • By Ali Shan
      Please clarify the following confusions one by one:-
       
      1. If we run P-delta analysis in ETABS, then should we ignore stiffness property modifiers for beams and columns? I have heard that if we perform P-delta analysis and apply stiffness modifiers at the same time then the moment magnification process is doubled...?
       
      2. ETABS considers selenderness of a column by applying moment magnification factors. If we run P-delta analysis also, does it mean that the selenderness of column is being over-estimated? I mean once the moments are magnified in P-delta analysis process and again through moment magnification process?
       
      Please help me understand the software myth and clarify above confusions.
    • By EngrJunaid
      AOA Respected Seniors !
       
      At station location 0.00 In column reinforcement summary the longitudinal steel is very high as compare to other location in the same column. My friend told me to ignore the 0 location reinforcement and provide the rebar in the column according to other station locations.
      here is a snapshot of the column summary, so should i ignore the location 0 reinforcement ????
       
      THANKS in advance.

    • By mhdhamood
      Dear all; 
      I have one story-  I found that the designer designed the columns only for axial loads neglected the moments from slabs... well I thinks it will work in case of gravity loads only.
      But this system will not carry a 1 Newton lateral load since its unstable system against lateral loads because the column model will be hinge at the top and pin at the bottom. 
      please lets know your opinions
    • By rummaan17
      Dear All,
      I happened to encounter an issue while designing Slender column for which I would like you all to put your feedback on.
       
      In, ETABS slender columns are designed with one of the method, moment magnification. (ACI 318-11 10.10.5). This method often result in high magnified moments because of the lower flexure stiffness EI computed from =0.4EI/(1+Bdns) (ACI 318-11 Eq 10-15).
      This problem is also address in one of the paper from Sturcutre Magazine. http://www.structuremag.org/?p=1005
       
      Has anybody have experience to utilize other method Elastic Second Order Analysis (ACI 318-11 10.10.4) or Non-Linear Second-Order Analysis (ACI 318-11 10.10.3) for design of Slender Column?. Especially with reference to ETABS.
       
      I appreciate sharing your kind knowledge and experience. Thanks
       
    • By mhdhamood
      Dear all;
      How to decide if shall I design the section as beam or as column.
      because as we know the horizontal element (beam) may also have axial force in addition to moment.
      like a column. I mean is there a limitation for the value of axial force to be neglected and then we deign as beam ?
    • By ahsun
      How can I calculate the required splice length for column?
       
      What will be effect on the structure, if someone on site provide the column splice length less than the required length? Will it create problem in load transfer or moment or stress? 
       
      What is the minimum column splice length can be provided? (With ACI Code Reference)
       
      Regards,
    • By waqar saleem
      salam
       
      Dear fellows 
       
      we have two concrete columns C1 and C2 with heights x and y .C1 is on the land and C2 is submerged in water.it is a test so there is no steel in the columns.we need to find the x and y on which these two columns will fail by crushing at the base.
       
      Regards
    • By asadishaq
      When is the right time to consider designing a shear wall instead of a column?Can you please guide me on some code provisions regarding this matter.
      what do you prefer, design a column with a cross section of 42"x10" or a structural wall of the same dimension? Both will be subject to gravity and lateral loads.
    • By waqar saleem
      salam everybody http://www.sepakistan.com/public/style_emoticons/#EMO_DIR#/smile.png
      what should be the minimum number of bars in a circular column???can we use just one bar at center of column?some said that one bar at center cant be used,minmum six bars should be used.
    • By waqar saleem
      what are stocky columns?where and why they are used ??
  • Recent Discussions

  • Latest Forum and Club Posts

    • 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? 
    • Hi, I was wondering why in some cases when i want to check torsional irregularity in etabs and use Story Max/Avg Drift from Modal explorer,  the software shows both Y and X direction ratio for Earthquake in X direction Or vice versa.  as far as i know when checking for EX with plus and minus Eccentricities, it should only report ratios for X direction not Y!  i should mention that this happen only in few cases!! in most of the time software report only X direction ratio for EX! thanks in advance for your time.
    • WA. Dear Junaid, 1. Your research topic is very important, being directly related to the professional engineering practice. Please do share the results & conclusions here, on completion of your research, for the benefit of forum users. 2. For obtaining relevant literature, you may adopt following methods: a. Your university will certainly be having subscription to one or more research publishing websites (like ScienceDirect etc). If so, you may search & download relevant research material from these websites. b. You may also request your colleagues studying in other universities to do a similar search on the websites subscribed by their institutions, in case their subscribed research sites are different.  c. Use Google search (with pdf option) to find out relevant research material from many other resources (international universities, research sharing sites like Research Gate & more), downloadable free of cost in several cases. Wish you best of luck in your research. Regards.
    • @Ayesha As we are using half scaled Model in our experiment so the objective of this similitude study is to determine a set of principles,correlation and conditions upon which our scaled model can be related to the prototype for predicting prototype performance.
    • In order to study the effect/performance of infill walls we are providing infill walls in our half scaled 2-story RC Frame model which we will be testing on 6DOF Shake Table here in Earthquake Engineering Center, UET Peshawar...
    • Interesting. I also don't have any experience with Similitude Study. I am curious to ask that what is the objective of this study?   
    • Wa alaikum us salam, I dont have any relevant info regarding similitude study but I found your research topic very interesting. By the way, Are you going to consider effect of infill walls as well? Best of luck.   
    • AoA , I am going to start my M.Sc. research on "Similitude study of scaled 3D RC Frame for seismic testing on 6DOF Shake Table". Need your expert opinion on this topic. It will be of great help if anyone on this forum have work on Similitude Study and share their experience,relevant research papers etc Thanks
    • Your question is not clear. If you explain your problem in a bit detail, you may get a more specific reply. However, if the purpose of your question is to know about general procedure of interpreting reinforcements given by SAP2000 software, it is given below. 1. When we design a concrete frame in SAP2000, it gives following different types of reinforcement: a. In case of columns, required areas of main (or vertical) steel bars and lateral (or ties) reinforcement. b.In case of beams, results are in the form of reinforcement areas for bottom & top main bars as well as stirrups. 2. Given area of steel for column vertical bars is to be converted to suitable number of bars (using theoretical bar areas, as we do for manual calculations) according to code requirements in such a way that the provided steel area is either equal to or a bit more than the area required by SAP2000. Similarly, reinforcement areas given for bottom & top bars of beam members are converted to suitable number & sizes of bars, such that provided steel area is either equal to or a bit more than the area required by the software. 3. Reinforcement areas provided by SAP2000 for column ties & beam stirrups can be converted to suitable tie & stirrup size and spacing, similar to that explained in the following thread for ETABS case: HTH Regards.
×

Important Information

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