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Foundation Design

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can you please tell me,

Why foundation is designed for STATIC LOAD CASES only.

Why not we design foundation for RESPONSE SPECTRUM CASES.

In our office  for G+24 also we design foundation only  for STATIC LOAD CASES,  is it wrong if we do foundation for static load cases

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You should design it for seismic case too. With response spectrum analysis, signs are lost and maybe that's why your office is not designing foundations for it but technically speaking,  foundations need to be designed for all ULS Load Cases based on LRFD. 


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Earth quake loads consider in foundation designs as well in its sizing as well as in its structural design. If someone omits, it purely his own choice


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    • 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.

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      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. 


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      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
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    • AOA 

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