SAP2000 File: Conventions

Description

Some differences between conventions used in SAP2000 and Strand7 are described below.

Numbering of Nodes and Elements

In SAP2000, joints, frames/cables, links, areas and solids are named individually using local naming systems.

In Strand7, beam, plate and brick elements are numbered individually using local numbering systems.

Beam Local Axes

Strand7	SAP2000
+3 axis	+1 axis	The 1 direction is along the beam.
+2 axis	+2 axis	The 2 direction at right angles to 1 in the plane of the reference vector.
+1 axis	-3 axis	The 3 direction is at right angles to 1 and 2.

See Beam Elements: Local and Principal Axes.

Plate Local Axes

Strand7	SAP2000
+x axis	+1 axis	The 1 axis lies in the global X-Y plane.
+y axis	+2 axis	The 2 axis has a positive sense in the +Z direction, unless the element lies in the global X-Y plane, where the 2 axis is taken to be parallel to the global +Y direction.
+z axis	+3 axis	The 2-3 plane is parallel to the global Z axis.

See Plate Elements: Local Axes.

Location of Beam Element Loads

SAP2000 gives beam locations as fractional values or absolute values. In the case of distributed loads, SAP2000 provides positions RelDistA/AbsDistA and RelDistB/AbsDistB relative to the first end of the beam.

Strand7 converts all locations to fractional values with respect to the first and second ends of the beam.

Direction of Plate Edge Normal Pressure

SAP2000 defines a positive pressure as acting inwards.

Strand7 defines a positive pressure as acting outwards.

Coordinate Systems

SAP2000 defines rectangular and cylindrical coordinate systems using Table: "COORDINATE SYSTEMS".

Strand7 posts these coordinate systems as new user-defined coordinate systems. General coordinate systems are not supported.

Groups

SAP2000 uses Table: "GROUPS 1 - DEFINITIONS" to define the name of a group. Strand7 uses these group names to define sub-groups.

SAP2000 uses Table: "GROUPS 2 - ASSIGNMENTS" to assign entities to a group. Strand7 supports the assignment of beams, plates, bricks and links to groups.

Group and Sub-Group Creation

Strand7 creates groups and sub-groups according to the group definitions. Sub-groups are defined under the default group SAP2000 Import "Filename.Ext". SAP2000 allows an entity to belong to more than one group. Strand7 allows entities to belong to one group only, and assumes that an entity belongs to the last specified group in which the entity was defined.

Load Cases

SAP2000 uses Table: "LOAD CASE DEFINITIONS" to define load cases.

Strand7 defines a load case/freedom case pair which corresponds to the SAP2000 load case.

A SAP2000 load case is a combination of a load case and freedom case as defined within Strand7. When importing a SAP2000 file, Strand7 creates a new load/freedom case pair corresponding to each SAP2000 load case to which all load case and freedom case dependent attributes are assigned.

Units

SAP2000 uses the Table: "PROGRAM CONTROL" to specify model units. The SAP2000 model units are consistent in terms of force, length and temperature.

Strand7 rescales all imported model data according to the existing Strand7 model units. The following SAP2000 units labels are supported:

lb-in-F
lb-ft-F
Kip-in-F
Kip-ft-F
KN-mm-C
KN-m-C
Kgf-mm-C
Kgf-m-C
N-mm-C
N-m-C
Ton-mm-C
Ton-m-C
KN-cm-C
Kgf-cm-C
N-cm-C
Ton-cm-C

Undefined Units

If the units are not defined by the PROGRAM CONTROL table, Strand7 assumes that no model units have been specified. If there are no entities contained within the model prior to import of the SAP2000 file, the model units are set to No Units. If entities exist prior to import, the current model units are assumed.