Strand7 modelling 1

[divyeshrohit]

Hello friends,
I am using Strand7 for the first time, I need to model a 2 storey 2D structure with isolated footings, can anybody help me in modelling isolated footing.

 

[glass99]

IDS: You are correct that even the FEMA formula is potentially problematic, though theoretically the FEMA formula has been vetted out for use in real world applications, and appropriate fudge factors applied by people who understand what they are doing.

 

[IDS]

I don't know which FEMA formula you are referring to, but I still don't see how fudge factors related to a grossly simplified model can be better than fudge factors applied to a somewhat less simplified model, assuming the factors are applied by people with an equal understanding of what they are doing.

Doug Jenkins
Interactive Design Services

http://newtonexcelbach.wordpress.com/

 

[yakpol]

IDS,

FEMA formula is THE FORMULA for footing springs under seismic loads. As far as I know it's the only one used in USA. Lots of work has been done do develop this formula, it's commonly accepted outside of US as well. More refined will be Method 2 presented in the same FEMA document - modeling subgrade reaction by a series of vertical compression only springs. Using elastic soil FE for this purpose is very uncommon, hard to defend and to come up with justifiable assumptions.

 

[IDS]

I don't think we are getting anywhere here. I'm not saying there is anything wrong with using springs if you have some way of coming up with suitable properties, I just prefer something less black box myself.

Doug Jenkins
Interactive Design Services

http://newtonexcelbach.wordpress.com/

 

[glass99]

Is the FEMA formula just a simplification of a linear elastic analysis which could otherwise be replicated in FE? I suspect is captures some other behaviors.

 

[divyeshrohit]

Thank you