Geometric nonlinearity

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Posts: 19
Joined: Tue Sep 17, 2019 2:38 pm

Geometric nonlinearity

Post by GianmarcoManzo » Tue Jan 14, 2020 5:18 pm

Hi, can you tell me if using the corotational formulation implemented in stko when I define a forcebeamcolumn element I can grasp both the large p-delta effects and the small p-delta effects? Thank you.

Posts: 220
Joined: Tue Oct 29, 2019 8:45 am

Re: Geometric nonlinearity

Post by STKO Team » Wed Jan 15, 2020 11:09 am

The p-Delta transfromation in OpenSEES only deals with p-(large)Delta effects.
The corotational transformation is a more complete form of geometric nonlinearity, involving large displacement and rotation, but neglecting finite strains (a complete nonlinear kinematics used in solid mechanics such as total or updated lagrangian have also finite strains using other strain measures such as the green-lagrange strain or logaritmic strain).

So the corotational transoformation should include the p-(large)Delta effects, but no the p-(small)delta effects. In fact it also neglects the effects of element loads, only dealing with nodal quantities. Thus if you want to include p-(small)delta effects, you may need to discretize your members.

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