Geometric nonlinearity

 Posts: 19
 Joined: Tue Sep 17, 2019 2:38 pm
Geometric nonlinearity
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 pdelta effects and the small pdelta effects? Thank you.
Re: Geometric nonlinearity
The pDelta 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 greenlagrange 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.
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 greenlagrange 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.