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  • Our picks

    • *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
    • 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
    • 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
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    • Hey, I’ve recently graduated from University with no real experience in work and was looking for a site engineering position to gain experience in the field. However couldn’t find one. So do you recommend me searching for a designer position in a consultant firm ?
    • Thank you. Brother i have also provide beam of 15"x30" in both direction as shown in figure (see attached fig). Beam of dimension 9"x14" would be suitable to provide in the 20ft span direction in step region which will be supported on beam(15"x30"? 
    • If you can design this slab with a 7" thickness, there is no need to provide a beam in the step region, because again a 14" depth won't be sufficient for a 30' span. And your beams would be projecting out on top of the wall,  which is not very good from an aesthetic point of view. Drop below the slab can also obstruct MEP services.
        This is a personal point of view by the way, technically you can provide beams in the steps region.
    • Yes brother, i have increased thickness to 7 inches. Is this a good idea to provide small beams of 12"x14" in the steps region?  
    • Thank you brother.   
    • 1) Its behaviour would be one way or two way? Depends on your design but 6" slab over a 20'x30' span is not fulfilling ACI's minimum depth requirements.   2) Is there any special detailing required in steps region? yes 4) The left side beam is rectangular-beam and right side beam is T-beam? left side is an inverted beam
    • For 1: It depends on the size of your riser relative to tread.         2:  Yes.       
    • Yes, it can be ignored at the top story if it is only at the top beam-column joint. The ratio should be satisfied at the bottom of the top story.
    • Firstly, conversion of reinforcement area for flexural (longitudial) beam reinforcement to 'number of bars' is similar to that for the vertical reinforcement of columns. However, for deciding the 'number of bars provided' in case of beams, we round the calculated value to next higher integer number only, whether it is even or odd. For example, if required steel area is 0.9 sq.in., and #5 bar is to be used, then required number of bars =0.9/0.307=2.93. In this case, we may use 3 #5 bars for the beam. (Whereas, in case of a square or rectangular column, we needed to use at least 4 bars.) Secondly, in case of a beam, required number of bars are to be provided along the relevant (top or bottom) face of the beam only, depending upon whether we are detailing the reinforcement for the negative or positive bending moment. In case, required number of bars (as calculated in previous paragraph) exceeds the maximum number of bars permissible in one layer, required number of bars will be provided in layers, separated vertically by spacers. Thirdly, total area of reinforcement provided, must be within the steel areas corresponding to Minimum & Maximum steel ratios prescribed by ACI 318 for the beams.  Fourthly, detailing of all type of beam reinforcement needs be in accordance with relevant provisions of ACI 318 and ACI 315 (whether seismic or non-seismic, as applicable).   Out of three reinforcement values shown along (the top or bottom side of) a beam, two outer values (0.9 & 0.9 at left & right sides of top face, and 0.6 & 0.4 at left & right sides of bottom face of the beam under discussion) indicate the amount of reinforcing steel required at the relevant (top & bottom) faces of the two supports. Whereas, the middle values (0.2 on the top, & the 0.6 on the bottom side) indicate the amount of reinforcing steel required at the mispan of the beam,  on the top & bottom faces respectively. HTH Regards.
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