STAAD.Pro Help

Node Specification dialog

Used to specify rigid links or specialized linkages in the structure. This facility can be used to model special structural elements such as ties or a floor diaphragm which makes the floor rigid for in-plane movements. The process is to select a node to act as the master and then degrees of freedom for which the slave nodes are linked to the master. Internally, STAAD will perform an automatic bandwidth reduction.

Note: Refer to TR.28 Rigid Diaphragm Modeling for additional details.

Opens when Node is clicked on the Specifications - Whole Structure dialog.

Note: STAAD.Pro V8i (SELECTseries 3) (release 20.07.08) and higher is capable of defining a rigid floor diaphragm without the need to specify a Master Node. This feature is only available by manually editing the STAAD input file. Refer to TR.28.2 Floor Diaphragm for additional details

Master/Slave tab

Master Node

It is called as such because the displacements of the slaved node will be based on the displacement of this Master node. From the drop-down list, select the node which should serve as the master node.

Slaved Directions
  • Rigid - This is a means of defining that the link which connects the master with the slave has infinite stiffness for all the six degrees of freedom. In other words, if one were to consider an imaginary object that has infinite stiffness axially, for shear, torsion and bending, that would be the type of link which connects the master and the slave.

    Note: By default, STAAD.Pro keeps this box checked. Un-check this box to activate the options described below.
  • XY, YZ, and ZX - This is a way of specifying a type of connection where the rigidity is limited to in-plane directions.

    The plane of this link is defined in terms of the global planes XY, YZ, or ZX. For example, if we have a concrete slab in a building, and the slab can be assumed to be nearly inflexible for translations along global X and global Z, and the rotation about global Y, that type of link would be called a "diaphragm" in global XZ.

    XY is equivalent to a master-slave relationship for the degrees of FX, FY and MZ. Similarly, YZ is equivalent to linking FY, FZ and MX, and, ZX is equivalent to linking FX, FZ and MY.

  • FX, FY, FZ, MX, MY, and MZ - This provides a way for linking just some specific degrees of freedom the user desires. For example, if one wishes to link FY and MZ, check these two options.

Floor Diaphragm tab

Diaphragm group
No Select diaphragm number.

Select the diaphragm type from the drop-down list:

Rigid - a diaphragm that translates & rotates as a rigid body.

Floor Level group

Select one of the options as the method to define the floor level of the diaphragm.

Height Type the global coordinate value (elevation), in Y direction, to specify floor level.
YRange Select this option to define the floor level by upper and lower bounds of Y coordinates.
YRange group

Used when the YRange option is selected.

Minimum The lower bound of Y coordinates for the Y range.

The upper bound of Y coordinates for the Y range.

Master Node Information group

Select the method used to define the master node of the diaphragm.

Calculate The diaphragm center of mass is determined and a node is created at that location to use as the master node.
Select Master Node Select the existing node to use from the drop-down list.
Define Floor Range Set this option to define the floor range as a XZ range of coordinates or by manually selecting coordinates.