01-10-2012, 11:24 PM
Designing a foundation for a transformer should not be any different than the foundation of a heavy machinery which is distributed over a large footprint area but
without the dynamic effects (a transformer will not create dynamic effects). You will still need to consider the lateral load due to seimic effect or wind if this applies to your case.
My suggestion is to create a large enough base-pedestal extending beyond the footprint of your transformer. The pedestal or base should be solid or made with concrete knee walls around the perimeter of the transformer; you may need to include a shallow pool/container below the transformer to contain any potential liquid (oil) spill).
The pedestal for your transformer should extend down to the top of your footing at the foundation level where you have enough soil bearing capacity. The area of foundation should be controlled by the allowable soil bearing pressure. If the seismic lateral force is large enough you need to consider it in the design of your foundation in addition to the vertical loads due to the weight of the equipment and depending if the bearing capacity of the soil has been established based on gross or net stresses you will need to add the weight of the foundation itself. If possible keep the eccentricity (e=M/N) within the base-dimension/6 so that you don't have loss of contact between the base and the soil. Check design for adequate safety factor against: bearing pressure, overturning moment, and sliding (using soil/concre friction coefficient).
without the dynamic effects (a transformer will not create dynamic effects). You will still need to consider the lateral load due to seimic effect or wind if this applies to your case.
My suggestion is to create a large enough base-pedestal extending beyond the footprint of your transformer. The pedestal or base should be solid or made with concrete knee walls around the perimeter of the transformer; you may need to include a shallow pool/container below the transformer to contain any potential liquid (oil) spill).
The pedestal for your transformer should extend down to the top of your footing at the foundation level where you have enough soil bearing capacity. The area of foundation should be controlled by the allowable soil bearing pressure. If the seismic lateral force is large enough you need to consider it in the design of your foundation in addition to the vertical loads due to the weight of the equipment and depending if the bearing capacity of the soil has been established based on gross or net stresses you will need to add the weight of the foundation itself. If possible keep the eccentricity (e=M/N) within the base-dimension/6 so that you don't have loss of contact between the base and the soil. Check design for adequate safety factor against: bearing pressure, overturning moment, and sliding (using soil/concre friction coefficient).
Yours truly, gulilero