TR.16.2 Physical Members

STAAD.Pro allows grouping analytical predefined members into physical members using a special member group PMEMBER. This command defines a group of analytical, collinear members with same cross section and material property.

To model using PMEMBER, you need to model regular analytical members and then, group those together.

While creating a PMEMBER, the following pre-requisites apply:

Existence of the analytical members in the member-list.
Selected members should be interconnected.
The selected individual members must be collinear (adjacent analytical members must lie within 5°).
Local axis of the individual members comprising the physical member should be identical (i.e., x, y and z are respectively parallel and in same sense).
Tip: You may select the Beam Tools > Beam Incidence tool in the Geometry Tools group on the Utilities ribbon tab in the STAAD.Pro Analytical Modeling workflow for modifying analytical members which are pointing in the wrong direction
A member in one physical member group can not be part of any other physical member group.

Note: The PMEMBER option can only be used for codes which explicitly support that command. Refer to the appropriate design code specification to confirm if that code supports PMEMBER design.

Description

A PMEMBER can be created either in the Analytical Modeling workflow or in the Steel Designer workflow. Analytical Modeling workflow and Steel Designer workflow PMEMBERs will be labeled as M and D, respectively. Modeling workflow PMEMBERs allow variable cross-sections. Steel Designer workflow allows importing of PMEMBERs created in the modeling mode.

To define a Physical Member, the following command is used after the MEMBER INCIDENCE command:

DEFINE PMEMBER

Member-list  PMEMBER pmember-no

Example

JOINT COORDINATE
1 0 0 0 6 10.0 0 0
MEMBER INCIDENCE
1 1 2 5
DEFINE PMEMBER
1 TO 5 PMEMB 1

To define the member property of a Physical Member, the following command is used:

PMEMBER PROPERTY

pmember-list  PRIS …

The physical member supports all types of member properties available in STAAD.Pro.

If multiple definitions of member properties for a particular analytical member is encountered (e.g., analytical member properties is defined twice, once via PMEMBER PROP command and again via the MEMBER PROP command, then the MEMBER PROP command will override the PMEMBER PROP definition.

To define the material constants of a physical member, the following command is used:

PMEMBER CONSTANTS

E CONCRETE pmember-list

DEN CONCRETE pmember-list

…

Any member, which is a part of any PMEMBER is not allowed to be assigned constants explicitly.

Note: Loads are applied directly to physical members using the PMEMBER LOAD command. Refer to TR.32.2.1 PMember Load Specification for details.

Design parameters are available for use with PMEMBERS by using the PMEMB list. The following syntax is used:

parameter value  PMEMB pmember-list

Example

RATIO 1.05 PMEMB 1 2

Note: There is not option to specify ALL for a PMEMB list, except for CODE CHECK or SELECT commands.

After the analysis, the Post Analysis results of a PMEMBER can be seen by using the following command:

PRINT PMEMBER FORCE

This command will produce member forces for all the analytical members in the group.