RE: Reached total force Fy- Prescribed displacement over a footing on piles example.

Dennis Waterman — Mon, 06 Feb 2023 10:15:07 GMT

Dear Mohamad,

1) They're both true .... it's just that in the Phases window it has already been multiplied with the slice thickness of 1m (or 2*pi if it's an axisymmetric model). But considering it's plane strain using the unit kN/m is probably better.

2) Indeed you should add the pile forces. However, not the minimum axial force, but the axial force at the pile head as that is the node where the prescribed displacement is applied and thus where the reaction is found.

3) In case of failure

4) The easiest way is to simply divide Fy over the width of the footing. However, you will get entirely the same results unless the footing is extremely stiff. When using a prescribed displacement you force the footing to settle perfectly equal as if the footing is infinitely stiff. If in reality it is not infinitely stiff with a line load the footing will bend a bit and thus your settlements will vary a bit over the footing.

5) The value of Fy is the reaction force to the prescribed displacement. It depends on whether the value is taken at failure or not, what you consider failure and whether you used (partial) load and material factors if you want to consider it an ultimate load, design load, allowable load or something else. That is not up to the software to decide, but up to the user.

With kind regards,

Dennis Waterman