TR.28.1 Master/Slave Specification

This set of commands may be used to model specialized linkages (displacement tying, rigid links) through the specification of master and slave joints. Please read the notes for restrictions.

General Format

SLAVE *{ XY | YZ | ZX | RIGID | FX | FY | FZ | MX | MY | MZ } MASTER j JOINT joint-spec

where:

joint-spec = { joint-list  | *{ XRANGE | YRANGE | ZRANGE } f1 f2 }

Description

The master/slave option provided in STAAD.Pro allows you to model specialized linkages (displacement tying, rigid links) in the system. For example, SLAVE FY … connects the two joints such that the Y displacement at the slave will be the sum of Y displacement at the master plus the rigid rotation,

R sin θ

Note that instead of providing a joint list for the slaved joints, a range of coordinate values (in global system) may be used. All joints whose coordinates are within the range are assumed to be slaved joints. For convenience, the coordinate range specified for slaved joints in this entry may include the master joint for this entry. However, master and slave joints of other entries must not be included in the coordinate range. All 2 or 3 ranges can be entered to form a "tube" or "box" for selecting joints in the tube or box region.

Fx, Fy etc. are the directions in which they are slaved (any combination may be entered).

If two or more entries have the same master, the slave lists will be merged. Please ensure that the same direction specs are used.

The direction specifiers (XY, YZ, ZX) are combinations of the basic directions, XY is the same as entering FX, FY, MZ; etc. Any combination of direction specifiers may be entered. An example of the use of this format is: a rigid diaphragm floor that still retains bending flexibility entered as SLA ZX … .

If RIGID or if all directions are provided, the joints are assumed to be rigidly connected as if SLA DIA RIG were entered, even if DIA is omitted.

Note: Due to the mechanisms used to include master/slave systems, if the reactions on master nodes are not included in a statics check then an out of balance report may result. This can be avoided by adding a short stiff member from a master node to the support.

Restrictions

Solid elements may not be connected to slave joints.
Master joints may not be master or slaves in another entry.
Slave joints may not be master or slaves in another entry.
Slave directions at joints may not be supported directions or have displacements imposed.
Master and/or slave joints may not be inclined supports.
The master/slave specification is only intended for linear static and dynamic analysis.
Multilinear springs are not permitted.
Master/slave joints may not be specified when rigid floor diaphragms are used (refer to TR.28.2 Floor Diaphragm).
If a CHANGE command is specified, then any master/slave joints must be re-specified if they are intended to be used after the change.

The internal processing of any master/slave command includes an automatic bandwidth reduction.

Example

Fully Rigid and Rigid Floor Diaphragm

SLAVE RIGID MASTER 22 JOINT 10 TO 45
SLAVE RIGID MASTER 70 JOINT YRANGE 25.5 27.5
SLA ZX MAS 80 JOINT YR 34.5 35.5