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Assalam o Alykum. What will be the allowable crack width value for water retaining structures ? As per ACI code. Incase outer face of water tank retaining wall is covered with soil and inner face with small amount of water for example 200mm. Shall we use the allowable crack width value for water retaining structures ? I read it's 0.1mm for water retaining and 0.3mm for soil.

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 I mean its just a suggestion and by the way this method 1 is obsolete now since ACI 318-99 (see point 2 above).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