Macroelement definition - eesd-epfl/OpenSees GitHub Wiki

The macroelement implementation is defined in the library Macroelement3d.dll (download binary or build the library). Different input structures are available to make the definition more straightforward for the use of the macroelement in different contexts. The first part of the input string, defining the geometry, is common to all input formats:

element Macroelement3d $eTag $nI $nJ $nE $aX $aY $aZ $oopX $oopY $oopZ <-flags>

Where:

The geometry and spatial orientation of the element is fully described by these inputs. Node E defines the barycentre of the element. The position of the end interfaces is calculated considering the orientation of the axis of the element and its length (defined in the second part of the input). Nodes I and J can be located in any position; if their location differs from the element ends, a rigid offset is defined.

The orientation of the section is defined by the out-of-plane vector. The in-plane vector is calculated as the one perpendicular to the plane defined by the vectors axis and oop, and the oop re-computed as the vector perpendicular to the plane defined by the in-plane vector and the axis. In such way, an orthonormal set of orientation axes is always defined, avoiding problems if the two input vectors axis and oop are not exactly perpendicular.

The sectional properties can be assigned following different input structures:

• Standard definition
• Tremuri-equivalent definition
• Generic fibre section
• Generic sectional models

Additional flags can be added to specify further options:

• Drift models for loss of lateral load and axial force capacity
• Additional flags

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