infrmDB cubic formulation

[leartt]

Greetings,
for the inelastic DB-beam-column elements, does SeismoStruct use the cubic formulation that is suggested by Izzudin [1991], as a function of the extremity rotations among other things? Is there a specific reason for assuming constant value of the axial force over its length?

[seismosoft]

Indeed, the infrmDB element follows the cubic formation. For details on its formulation refer to:
https://help.seismosoft.com/seismostruc ... nfrmdb.htm

The model assumes constant axial deformation and linear curvature distribution along the element length, which is exact only for prismatic linear elastic elements. Consequently, infrmDB should be employed with members of small length, leading to the need for a mesh refinement (4-5 infrmDB elements per member).

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