I guess this may have been asked before but i could not find a satisfactory answer. Here we go.
I understand that pile (embedded beam row) can be molded as both elastic and elasto-plastic material with limit N and M.
When modeled as elastic material, strength reduction can not be applied to these structural elements during safety factor calculation. This means that as long as structural capacity of the structural element is not exceeded the safety calculation should give the correct result. And structural capacity of the beam or pile needs to be checked manually, if you suspect they may be exceeded. Are these correct assumptions?
How the strength reduction is applied to embedded row elements (and other structural elements such as geogrids and anchors) , when elasto-plastic material is selected?
Is the reduction applied to the structural capacity and/or base, lateral and axial resistances? Or simply the stresses capped to the the limiting Np, Mp values and these elements would not loaded stresses that causes exceeding Np and Mp?
I don't understand why structural capacity should be reduced during the safety analysis. We add piles with a predetermined size/capacity to stabilize the soil / increase the factor of safety. Therefore predetermined size/strength should enter into the equation without reduction.
Thanks in advance,
Bulent Hatipoglu said:When modeled as elastic material, strength reduction can not be applied to these structural elements during safety factor calculation. This means that as long as structural capacity of the structural element is not exceeded the safety calculation should give the correct result. And structural capacity of the beam or pile needs to be checked manually, if you suspect they may be exceeded. Are these correct assumptions?
Yes, you are correct about this assumption, as an elastic material does not have a capacity, the PLAXIS calculation does not have any information on limiting the development of internal forces.
You have set a maximum allowable internal force if you model the structural element as elastoplastic. This will also be respected during the Safety analysis, so in that case, the force will not exceed these internal force values, and you may see the development of e.g. plastic hinges.
During the Safety analysis, the strength of the soil material will be reduced via the ΣMsf parameter by default, while this is not done for structural elements. However, you can also activate the strength reduction for structural elements by checking the "Apply strength reduction"-checkbox in your phase's Staged Construction settings for each structural object.
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