Modeling Piles in Risa 1

[eit09]

I am going to design a large pile supported mat with RISA3D (In the past I've used pcaMats). My approach (before your comments/suggestions) will be modeling T/C springs for the piles and modeling plates for the mat.

My main concern is the spring constants for the piles that may be in T & C depending on the LC. When I start this design I will run the model using T/C sprngs using the k value for the compression piles. For each LC that flags a tensions spring I will have a separate model (for that specific LC) and change those springs to tension only with the tension k value.

This approach will probably give me about 10 separate models considering all Load Cases. I would like to know how others design pile foundations with RISA or some suggestions on a different approach other than having so many separate models?

Wouldn't it would be nice to be able to assign a single spring a tension constant and a compression constant? I bet that would be a programmer’s nightmare though!

 

[JoshPlumSE]

EIT -

There is an easier way to do it. Model a short link beam for your pile. The top node can have a tension only spring applied to it and the bottom a compression only spring. Since the two nodes should essentially move the same amount for all LC's, you will effectively be using a different spring constant for tension versus compression.

 

[eit09]

Indeed easier, So simple yet I never thought of using a rigid link!