9.13 Nodal Reaction Element

The element is used to constrain nodal displacements/rotations in any direction to specified values, to compute support reactions and to provide elastic suppports to nodes. The element is defined by a single directed axis through a specified nodal point, by a linear extensional spring along the axis or by a linear rotational spring about the axis. The element is essentially a spring which can have axial displacement stiffness or rotational stiffness. There is no limit to the number of boundary elements which can be applied at any nodal point to produce the desired effects.

NODAL_REACTION

Element_name = NODAL_REACTION Kinem = kinem, etc...

m, stiff(m), ( an(i, m), i = 1, nsd ) < m = 1, numat >

< connectivity data >

< terminate with a blank record >.

9.13.1 Element Group Control Information

Must follow the element name (same data record), and define the control parameters in the following form: KINEM = kinem, etc...

Note Variable Name Default Description

KINEM [0] Boundary condition code

= 0 Displacement option

= 1 Rotation option

9.13.2 Geometric / Material Properties Data (Numat sets)

Note Variable Default Description

M [0] Geometric/material set number

STIFF(M) [0.0] Spring constant k

AN(1,M) [0.0] Component 1 of direction vector N

AN(2,M) [0.0] Component 2 of direction vector N

AN(3,M) [0.0] Component 3 of direction vector N

9.13.3 Element Nodal Connectivity Data

Consult Chapter 11 for details; for this element NEN = 1.

9.13.4 Element Output History Requests

"On-line" and Calcomp plots of various element response components may be obtained. Each component required is plotted versus time. Plots of this type are useful in providing quick information concerning the time history behavior of important data. The total number of components to be plotted must equal NOUT, which is defined on the element group control record (see Section 9.10.1).

Note Variable Default Description

(1) N [0] Element number 1 and Numel

(2) NG [0] Generation increment 0

(3) NTEMP(1) [0] Component number 1 and 2

NTEMP(2) [0] Component number 1 and 2

Notes/

(1) Element components history output data must be input for elements at which the time history of one or more components is to be plotted. Records need not be read in order. Terminate with a blank record.

(2) Element components history output data can be generated by employing a two record sequence as follows:

Record 1: L,LG,LTEMP(1),LTEMP(2)

Record 2: N,NG,NTEMP(1),NTEMP(2)

The output time history requests of all elements

L+LG, L+2*LG,..., N-MOD(N-L,LG)

(i.e., less than N) are set equal to those of node L. If LG is blank or zero, no generation takes place between L and N.

(3) Two different component numbers may be plotted as described above. The corresponding component numbers and output labels are:

Component Number Description Output Label

1 Displacement /Rotation DELT

2 Force/Moment FORC

Notes . .