Dynamic Foundation Analysis Programs 1

Not user friendly, no error checking, probably it's the worst user friendly software I had seen.

[red]In terms of soil damping impedance and stiffness output,[/red]it's the probably the only widely acceptable commercial software for machine foundation analysis. The other one is DynaN from Ensoft Inc and the author actually worked under Novak as well. The DynaN is quite similar to Dyna6 and probably the source is the same, yet not as popular as Dyna6

My advice to you are the followings:

1. Dyna6 is good for rigid block type machine foundation analysis. It has only one module for flexible mat (when width/thickness>10) but is very limited and only considering vertical excitation load so it’s not that much useful.

2. The most valuable part of Dyna6 is the soil damping impedance and stiffness output, which is the only source for boundary condition setup. It’s almost impossible for manual calculation for the K and C as they are frequency dependent and the amount of work is tremendous. The rest, the dynamic analysis part, any software like SAP2000 and STADD Pro can do a better job with better output, especially the SAP2000, the pre and post process user interface is the best.

3. Use Dyna6 only for rigid block type machine foundation. Be careful when the foundation is flexible and multiple rotors, such cases as

1) Table top
2) Mat with width/thickness >10
3) Multiple rotors such as Gas Turbine and Steam Turbine Generator with different rotor speed and phase difference

For these cases just use Dyna6 for soil damping impedance and stiffness output and relay to SAP2000 or STAAD Pro for FEM dynamic analysis.

4) When run Dyna6, generate the input data output (I forgot where it stored but it creates one) and double check you input data, especially the unit. Dyna6 will give you an output without error checking so be careful on your input data correctness. In many times it’s caused by the unit like kg and Newton etc and it has >10 times difference yet Dyna6 still gives you an output

Thanks amec2004...

I've also heard you can generate foundation frequencies from RISA 3D, but don't know if that is associated with the rigid block machine foundations.

Anyone havae ny experience with that program in this area?

Mike McCann
MMC Engineering

RISA 3D shall be the same as SAP2000 and STAAD Pro. These generic structural software have more flexibility in dynamic analysis using FEM model, not limited to a single lumped mass model which is the only choice in DYNA6, but the FEM model boundary condition (soil damping C and stiffness K) has to rely on DYNA 6’s output or manual calculation.

For manual calculation of K and C, many users use the charts and tables in the classic book Design of Structure and Foundation for Vibrating Machines by Suresh Arya Michael ONeil and George Pincus, or Chapter 20 in Foundation Analysis and Design 5th Ed by Joseph Bowles which are extracted from Novak's papers, same as what DYNA6 is used. These charts and tables has many limitations such as no layered but only homogeneous soil, no frequency dependent K and C, only tables for concrete and timber pile but no steel pile etc. Despite these limitations, the manual calculation of K and C is still widely used in many important machine foundations such as Gas Turbine or Steam Turbine foundation design, in many big company world wide.

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yeah, i have seen some calculations for compressor foundation using our in house excel program and staad/risa using time history analysis. i trust our in house excel program more than staad/risa that uses plate/solid elements with rigid dummy members.

the book by arya is a good guide for this. fluor has a good design guide for dynamic compressor foundation if you can find one.

>> fluor has a good design guide for dynamic compressor foundation if you can find one

The Fluor design practice is also based on Novak's papers, but with more step by step details.

You will find all the references available are based on Novak's papers, Design of Structure and Foundation for Vibrating Machines by Suresh Arya , Foundation Analysis and Design 5th Ed by Joseph Bowles , Canadian Foundation Engineering Manual 4 Ed, Fluor Design Practice and Bechtel Engineering Design Guide.

You can use these references to create your own in Excel spreadsheet if you are confident on yourself ...

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Thanks guys. I really appreciate the information.

Mike McCann
MMC Engineering