Theory II. Order

03-Analytical/modelling capabilities
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Posts: 9
Joined: 19 Apr 2021, 15:47

Theory II. Order

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Dear all,

I have a question:
How is nonlinearity implemented in the program?
Physical nonlinearity is included in the material laws.
How is geometric nonlinearity implemented? How is it implemented according to Theory II. Order?

Thanks and kind regards,
Posts: 972
Joined: 22 Jul 2011, 10:19
Location: Cookeville, Tennessee, USA

Re: Theory II. Order

Post by huffte »

I will suggest the section of the SeismoStruct Help System quoted below as a starting point. I hope this helps.

"Geometric Nonlinearity
Large displacements/rotations and large independent deformations relative to the frame element's chord (also known as P-Delta effects) are taken into account in SeismoStruct, through the employment of a total co-rotational formulation developed and implemented by Correia and Virtuoso [2006].

The implemented total co-rotational formulation is based on an exact description of the kinematic transformations associated with large displacements and three-dimensional rotations of the beam-column member. This leads to the correct definition of the element's independent deformations and forces, as well as to the natural definition of the effects of geometrical non-linearities on the stiffness matrix."

Correia A.A., Virtuoso F.B.E. [2006] "Nonlinear Analysis of Space Frames," Proceedings of the Third European Conference on Computational Mechanics: Solids, Structures and Coupled Problems in Engineering, Mota Soares et al. (Eds.), Lisbon, Portugal.
Tim Huff
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