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  • Our picks

    • 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

       

       
      • 4 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

       
      • 9 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
    • 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.
      • 1 reply
    • 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
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    • By UmarMakhzumi
      The following excerpts are from B F Goodrich v Wohlgemoth case in which a young engineer named Donald Wohlgemuth who walked over from B. F. Goodrich to a competitor, International Latex, and then discovered, to his shock, that Goodrich objected. Brooks(Author of the book from which this text is copied) traces the story of how Goodrich dragged the young man into court to stop him sharing secrets of the space suit they were designing for Mercury astronauts. You will like it if you are related to Law or Engineering. Here is the case:
      Donald Wolhgemoth worked his entire career in the ‘pressure space suit department’ at B F Goodrich and had risen through the ranks to be manager of this highly specialized department in charge of all research and development regarding space suits. In 1964, Wohlgemuth announced his resignation to go to work for International Latex Corporation in their space suit department, which was 14 years behind B F Goodrich in the development of this specialised technology.
      B F Goodrich sued Wohlgemuth to protect its trade secrets. There was no evidence of actual misappropriation of any trade secrets although Wohlgemuth was reported to have said to fellow
      employees that ‘loyalty and ethics had their price; insofar as he was concerned, International Latex was paying that price.’Based on this record, the court had no reservation granting injunctive relief to prevent the threatened misappropriation of trade secrets.
      The court decreed ‘We have no doubt that an injunction may issue in a court of equity to prevent a future wrong although no right has yet been violated.’ Further, the court stated, ‘unless a restraining order is entered, Goodrich may suffer irreparable injury.’
      The scenario now is that an employer seeking injunctive protection for his trade secrets prior to their disclosure has to allege that either the ex-employee actually intends to do so or that the type of work is such that he is subconsciously doing so.
      The situationis such that the threat of misappropriation of trade secrets can be enjoined without regard to proof of actual misappropriation or the intent of the former employee. This is called the doctrine of 'inevitable disclosure'.
      However, the judgement passed allowed Wohlgemuth to work for Latex in the Space Suit Department as long as he keeps trade secrets to himself. The reason I am posting this is one, that it is quite relevent to what we engineers do day to day and two, that the following arguments that were presented by the defense, which I really enjoyed.
      “Usually it is not until there is evidence that the employee [who has changed jobs] has not lived up to his contract, expressed or implied, to maintain secrecy, that the former employer can take action. In the law of torts there is the maxim: Every dog has one free bite. A dog cannot be presumed to be vicious until he has proved that he is by biting someone. As with a dog, the former employer may have to wait for a former employee to commit some overt act before he can act.”
      Thanks.
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    • There are two three columns in a grid ,two are placed in the same line another is to the downward side of the two columns,The two collinear columns are at 5 m apart and the next column is at 1.5 m apart tentatively.What the engineer has done is,tie the two collinear columns with strap beam,because the edge is on the property line and moreover at a large distance apart and the interior column is combined with the downward column (the downward column is at property line too).Is it possible to use combined footing and strap footing at the same time?My concern is ,the engineer has not separated out two designs for the combined behavior of the footing ,he has designed it as separate,one is  strap footing ,the other is combined. Is it because ,the pressure intensity  disperses over large area ,so he has taken it as single behavior?Wont there be site difficulty during casting?And is the design ok??I have attached the file herewith.
    • See this topic:    It depends. I have seen some embassies get blast wall designed considering the terror threat they face. Search the forum.
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    • There is also another point in this discussion. The assumption of a fixed based for isolated foundations is not valid because these foundations are susceptible to rotation. That would mean no moment (there would be some as foundation has rotational stiffness) at column foundation interface and more moment at beam column interface  - plastic hinging in beams column joint.  Although the original discussion is about developing plastic hinge at foundation column interface but I think the fact that isolated foundations rotate makes these two conditions  mutually exclusive (some degree). If the foundation rotates then it is a pinned end and the only forces there would be shear and axial.  
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