Use of HSsmall versus Hardening Soil

Question

Dear Reader, 
 In the last phases of my thesis, I got a question about the use of HSsmall especially if this is added value to for example just Hardening soil. Is there a way to quantify/express the effect of the HSsmall model without doing the same calculations with Hardening soil (for example pinpoint location on modulus reduction curve etc?) 
 
 Thank you in advance!

Stefanos Papavasileiou · Answer

Dear Daan, 
 I think you need to understand the reason why the Hardening Soil with small strain stiffness constitutive model was needed in the first place. That is explained in our Materials model manual. 
 Now, how can you quantify or express the effect of HSsmall in your model without running an analysis? Well, that is tricky as you need to know if you do have small strains in your model and whether these will have an effect on your analysis. Typically far away from the area of interest, small strains exist, which means the soil will behave stiffer. If however, the main purpose of your project is to see the way a building deforms next to an excavation probably large strains are realised and therefore the effect of small strain theory will not make a big difference. 
 This is a too broad a question to be able to answer in a single post, but I am sure with some research on our documentation and online you can find a way to answer it yourself.