Mat Reinforcement for Centrifugal Compressors? 1

[Hookem]

What design approaches have ya'll seen/implemented regards use of layering of rebar in the mat of pipeline compressors, be they centrifugal or reciproating (10,000 to 40,000 hp)? Specifically, I have seen one of the following two approaches: 1) rebar layering throughout the thickness of the mat that is uniform in size and spacing; and, 2) rebar layering, one at top & one at bottom, with no rebar between. What are pros/cons of each of these? Is there a better method? As the concrete mass is usually 3 or 5 times the mass of the compressor, and the unit soil loading less than 1000 psf, the rebar is usually put in only for temperature (.0018 time area).

 

[jheidt2543]

The rebar is installed where it will improve the structural capacity of the foundation, that is where the tension forces are the highest. Since, the foundation for a compressor is subjected to dynamic loads that can change from compression to tension, the two layer approach of top and bottom rebar is the correct one. The center of the foundation is the neutral axis region.

For temperture reinforcing, rebar in the four faces of the foundation can be used to control cracking.