import numpy as np
import openseespy.opensees as ops
[docs]
def beam_geom_transf(
nodeTagI: int, nodeTagJ: int, transfType: str, dI: list = None, dJ: list = None
):
"""Output the geometric transformation tag of the beam element according to the node tag previously defined.
This function divide beam elements into two classes, vertical ones and non-vertical ones,
vertical elements ``vecxz = [-1, 0, 0]``, and non-vertical elements ``vecxz = [0, 0, 1]``.
See `geomTransf commands doc <https://openseespydoc.readthedocs.io/en/latest/src/geomTransf.html>`_
Parameters
----------
nodeTagI : int
Previously defined I-end node tag.
nodeTagJ : int
Previously defined J-end node tag.
transfType : str
Geometric transformation type, one of ['Linear', 'PDelta', 'Corotational'].
dI: list, optional, default=None
joint offset values – offsets specified with respect to the global coordinate
system for element-end node i (the number of arguments depends on the dimensions of the current model).
dJ: list, optional, default=None
joint offset values – offsets specified with respect to the global coordinate
system for element-end node j (the number of arguments depends on the dimensions of the current model).
Returns
-------
int
Geometric transformation tag that this function internally defined.
"""
coordI, coordJ = ops.nodeCoord(nodeTagI), ops.nodeCoord(nodeTagJ)
if len(coordI) < 3 or len(coordJ) < 3:
raise ValueError("This geometric transformations only for 3D!")
if transfType not in ["Linear", "PDelta", "Corotational"]:
raise ValueError(
"transfType must be one of ['Linear', 'PDelta', 'Corotational']!"
)
coordI = np.array(coordI)
coordJ = np.array(coordJ)
xaxis = coordJ - coordI
global_z = [0, 0, 1]
cos_angle = xaxis.dot(global_z) / (np.linalg.norm(xaxis) * np.linalg.norm(global_z))
if np.abs(1 - cos_angle**2) < 1e-10:
tag = _creat_geom_transf(transfType, dI=dI, dJ=dJ, ver=True)
else:
tag = _creat_geom_transf(transfType, dI=dI, dJ=dJ, ver=False)
return tag
def _creat_geom_transf(
transfType: str, dI: list = None, dJ: list = None, ver: bool = False
):
CrdTransfTags = ops.getCrdTransfTags()
if len(CrdTransfTags) > 0:
tag = int(np.max(CrdTransfTags) + 1)
else:
tag = 1
if ver:
vecxz = [-1.0, 0.0, 0.0]
else:
vecxz = [0.0, 0.0, 1.0]
if dI is None and dJ is None:
ops.geomTransf(transfType, tag, *vecxz)
elif dI and dJ:
ops.geomTransf(transfType, tag, *vecxz, "-jntOffset", *dI, *dJ)
else:
raise ValueError("dI and dJ must be both None or input at the same time!")
return tag
