Concrete Design - Thermal

[TPWells]

Hi,

I am currently designing a concrete basin in staad (Approx 12m x 20m) and 4m in height. There is a very large range of temperature on the site it is to be constructed. I am going to use all the relevant codes and standards in order to take on board thermal cracking and keep crack width to a minimum for water retention. My question is, when setting up my staad model, do I need to add in the max temp +43 degrees and min Temp -40 degrees for axial elongation. As the basin is on piles, this would lead to a very large load and I don't think this is the correct approach? Could someone please help? Also, I have not applied the temp differences to the pile caps as these will be buried.

Thanks,

Tim

 

[Ron]

TPWells.....while we often analyze for the full range of thermal action, this can be fundamentally very conservative. The concrete moves differentially by the variation from its placement/setting temperature. As an example, if the concrete was placed with a temperature of 25C and the expected max temperature is 43C, then the expansion differential is 18 degrees. Conversely its shrinkage is from 25 to the lower limit.

To use the full range for thermal expansion would require that your concrete be placed and initially hardened at the extreme low temperature of your range....not likely.