Selected Datasets

Element Attributes

All element attributes are stored in the ETAB.branch relational tables (dictionaries). The tables are accessed either by the MemCom relational table manipulation functions (C API) or with the Python module tb object. ETAB.branch is an array of NE relational tables, where NE is the number of elements (of the branch).

Common Attributes

Element attributes common to **all** elements
Keyword	Type	Description
`EID`	I	External element identifier (integer of type `mcInt32`).
`ITYP`	I	List of internal element node indexes defining the element, i.e. the element connectivity list (array of integers of type `mcInt32`). The size of the array is equal to NNE, where NNE is the number of nodes defining the element. Note that there are exception to this, namely elements witha variable number of nodes.

Solid Mechanics Elements

If a specific keyword is not listed in one of the sections below, then this keyword is described in the general description of ETAB.branch.

Rod/Cable Elements **Rx.S**
Keyword	Type	Description
`ECC`	F	If specified, the array contains rod or cable prestress information. If `ECC[0]=1`, `ECC[1]` contains initial pre-strain in axial direction. If `ECC[0]=2`, `ECC[1]` contains the initial pre-stress in axial direction. If `ECC[0]=3`, `ECC[1]` contains the initial pre-stress force in axial direction.
`MID`	I	Element material identifier pointing to dataset `MATERIAL.<MID>`, see MATERIAL.<mid>.
`TL`	F	Array `TL[0]` contains the rod or cable cross section area.

Beam Elements **Bx.S.RS**
Keyword	Type	Description
`ECC`	F	Array containing the (optional) node eccentricities (nodal offset vectors) `x1 y1 z1 x2 y2 z2 ...` for each node of the beam element, defined in the branch (global) reference frame.
`ENDRELEASE1`	I	Beam start node release code.
`ENDRELEASE2`	I	Beam end node release code.
`MBASE`	F	Array containing the beam local coordinate system definition. `MBASE[0]` can take the values 30 or 31. See additional information on mbase.
`MID`	I	Element material identifier pointing to dataset `MATERIAL.<MID>`, see MATERIAL.<mid>.
`PID`	I	External property identifier pointing to datatset `PROPERTY.<PID>`, see PROPERTY.<pid> Element properties.

2-dimensional Qx, Tx elements
Keyword	Type	Description
`ECC`	F	Array containing optional node eccentricities.
`MBASE`	F	Optional array containing the element local coordinate system definition. See below. If not specified the material orientation system is the (branch) global system. See additional information on mbase.
`MID`	I	Element material identifier pointing to dataset `MATERIAL.<MID>`, see MATERIAL.<mid>.
`PID`	I	External property identifier pointing to dataset PROPERTY.<pid> Element properties.
`TL`	F	Array containing the element thickness at the element nodes. If the array size is 1, the thickness is constant over the element, otherwise a thickness value for each of the element nodes is specified.

MBASE Additional Information

Unless described otherwise in element specific descriptions of ETAB, the first array element of MBASE contains the type and the remaining 9 array elements the parameters describing the element material reference coordinate system:

MBASE[0]=0: The material reference coordinate system is identical to the branch-global coordinate system, the base vectors being dummy values.
MBASE[0]=1: The material reference coordinate system is defined by 3 base vectors MBASE[1:3], MBASE[4:6], MBASE[7:9] with respect to the branch-global coordinate system.
MBASE[0]=2: The material reference coordinate system is defined by base vectors MBASE[1:3], MBASE[4:6], MBASE[7:9] with respect to the element-local coordinate system.
MBASE[0]=3: The material reference coordinate system is defined by base vectors MBASE[1:3], MBASE[4:6], MBASE[7:9] with respect to the integration point local coordinate system.,
MBASE[0]=1: The material reference coordinate system is defined by angles of orientation MBASE[1:3] with respect to the branch-global coordinate system.
MBASE[0]=12: The material reference coordinate system is defined
by angles of orientation MBASE[1:3] with respect to the element-local coordinate system.
MBASE[0]=13: The material reference coordinate system is defined by angles of orientation MBASE[1:3] with respect to the integration point local coordinate system.
MBASE[0]=30 :MBASE[1] specifies an (internal) beam reference node identifier which, together with the node identifier of the first beam node NODES[0] (see ETAB.branch), defines the local beam y-axis.
MBASE[0]=31 : MBASE[1:3] specifies a beam reference orientation base vector \(b\). The beam local coordinate system base vectors (\(e_{x}\), \(e_{y}\), \(e_{z}\)) are then defined as follows: \(e_{x} = P_{2} - P _{1}\), where \(P_{1}\) is the coordinate array of the beam start node and \(P_{2}\) the coordinate array of the beam end node. See also datasets COOR.branch and ETAB.branch). Then, \(e_{z} = a \times b\) and \(e_{y} = e_{z} \times e_{x}\). All vectors are normalized.

ENDRELEASE Additional Information

The beam element release flags are bit-coded ENDRELEASE as follows: A bit is set to 1 if the corresponding DOF is locked and free otherwise. Note that bits are numbered starting from 0 and the DOFs are numbered staring from 1:

Bit	DOF
0	1
1	2
2	3
3	4
4	5
5	6

If the ENDRELEASE parameter is absent all beam DOFs are free.

Materials

DOF Fields

DOF fields are 2-dimensional arrays containing F float data pertaining to nodes or elements of the mesh.One single dataset containing the array is defined per branch and case, subcase, cycle, and subcycle. The dataset name gname.br.cycle.subcycle.case.subcase is composed of

gname (the generic name as listed below),
br (the branch identifier),
cycle (the computational cycle identifier),
subcycle (the computational subcycle identifier),
case (the ‘load’ case identifier),
subcase or mode (the ‘load’ subcase or eigenmode identifier)

The FIELDS dataset contains table with attributes describing all defined fields of the current model. The summary of DOF fields below is not exhaustive - it reflects the current standard of B2000++.

DOF Fields Summary
Dataset name	Description
`DISP`	Displacements and optional rotations (usually) at the mesh nodes. Generated by the input processor.
`FORC`	Forces and optional moments (usually) applied to the mesh nodes. Generated by the input processor.
`HEAT`	Concentrated heat values acting (usually) at the mesh nodes.
`RCFO`	‘Reaction’ forces and moments computed by the relevant solver (usually) at the mesh nodes.
`RHEAT`	Concentrated heat values computed by the relevant solver (usually) at the mesh nodes.
`TEMP`	Temperatures computed by the relevant solver (usually) at the mesh nodes.

Sampling Point Fields

Sampling point fields contain ‘derived’ quantities of the DOF fields and they are stored element-wise in “Array Tables” AT datatype. They can contain a variable number of columns for each element, where a column represents a ‘sampling’ or element integration point. In the current version of B2000++ the sampling points are collected in groups, see the table below.

One single dataset containing the array is defined per branch and case, subcase, cycle, and subcycle. The dataset name gname.br.cycle.subcycle.case.subcase is composed of

gname (the generic name as listed below),
br (the branch identifier),
cycle (the computational cycle identifier),
subcycle (the computational subcycle identifier),
case (the ‘load’ case identifier),
subcase or mode (the ‘load’ subcase or eigenmode identifier)

The FIELDS dataset contains tables with attributes describing all defined sampling point fields of the current model. The summary of gradient fields below is not exhaustive - it reflects the current standard of B2000++.

Sampling Point Field Names
Dataset name	Description
`STRAIN`	Sampling point fields containing strain tensors with 6 components at integration points. The reference system is global.
`STRESS`	Sampling point fields containing stress tensors with 6 components at integration points. The reference system is global.
`STRAIN_SECTION_ROD`	Sampling point fields containing strain tensors with 1 component at rod and cable element sections. The reference system is element-local.
`STRESS_SECTION_ROD`	Sampling point fields containing stress tensors with 1 component at rod and cable element sections. The reference system is element-local.
`FORCE_ELEMENT`	Sampling point fields containing 3 force components at rod element sections. The forces are computed with respect to the deformed system (non-linear analysis). The reference system is global.
`FORCE_SECTION_BEAM`	Sampling point fields containing the 3 section force components (\(F_x\), \(F_y\), \(F_z\)) at integration points, expressed in the element-local coordinate system, computed with respect to the deformed configuration (non-linear analysis). \(F_x\) is evaluated at the cross-section centroid; \(F_y\) and \(F_z\) at the shear center. See also beam element reference.
`FORCE_SECTION_ROD`	Sampling point fields containing 1 force component at rod element sections in the rod direction (local x-axis).
`MOMENT_SECTION_BEAM`	Sampling point fields containing the 3 section moment components (\(M_x\), \(M_y\), \(M_z\)) at integration points, expressed in the element-local coordinate system, computed with respect to the deformed configuration (non-linear analysis). \(M_x\) is evaluated at the cross-section shear center; \(M_y\) and \(M_z\) at the centroid. See also beam element reference.