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UNITS

There is one-to-one mapping between Perform3D and ETABS units for force and length. Temperature unit is automatically determined based on the basis the other unit settings.

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There is no tower and story information available in a Perform3D model. Therefore, ETABS will create one tower and provides provide an option to select story levels by showing the following dialog box similar to what's done for other model files importing imported into ETABS.

The import process will always add the following message in the import report for addition of Stories.   

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The importing process will also report the number of each of the following types of materials imported into the ETABS model: 

• Inelastic fiber materialsconcrete material
• Inelastic steel material, non-buckling materials
• Elastic material for fiber materialssections
• Elastic shear materialsmaterial for a wall
• Elastic slab materialsmaterial for a slab or shell

When an inelastic material is translated from Perform3D to ETABS, the F-D relationship in Perform3D material is converted into a user stress-strain curve in ETABS.

• If the Perform3D material has cyclic degradation factors, then “Degrading” type hysteresis is assigned to ETABS material.
• If Perform3D point “Y” degradation factor is assigned to Energy factor at yield in ETABS, Perform3D point “L” degradation factor is assigned to Energy factor at moderate deformation in ETABS, Perform3D point “X” degradation factor is assigned to Energy factor at maximum deformation in ETABS.
• The Perform3D “Unloading Stiffness Factor” is translated to an ETABS "Stiffness Degradation Weighting Factor" with the help of following equation.

(Perform3D Unloading Stiffness Factor) = -2 * (ETABS Stiffness Degradation Weighting Factor) + 1

Since Perform3D Inelastic material do not have shear modulus (G), the said value is calculated for the ETABS material. Similarly Elastic Shear Material for a Wall in Perform3D does not have any modulus of elasticity (E), so E is calculated for the translated material in ETABS.

The following rules are used during import of concrete and steel nonlinear properties to compute stress-strain curves: 

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A sample of the Tower and Stories Materials section of import report is shown below: 

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There is a one-to-one mapping of section properties from Perform3D beam and column Cross-Sections into the ETABS frame section properties. All stiffness modifiers will be set to default in this case. The importing process will also report the total number of each of beam and column sections imported from Perform3D into the ETABS model. This information is given in the import report.  . 

“Column, Inelastic Fiber Sections” and “Beams, Inelastic Fiber Sections” from Perform3D model are translated into the Fiber P-M2-M3 Hinge and the Fiber P-M3 Hinge respectively. ETABS Fiber Hinges need hinge length input and hinge length definition. This information in Perform3D is handled automatically based on the frame compounds.  Therefore, if an inelastic fiber section in Perform3D is used multiple times in frame compounds with different hinge lengths then one fiber hinge is created in ETABS model for EACH fiber section hinge length set and the hinge length is suffixed to the ETABS fiber hinge name.

A sample of the Frame Sections portion of the import report is shown below: 

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ETABS imports the following types of Hinges:

• For Beams: Curvature Type Moment Hinge Moment Hinge, Rotation Type
• For Beams: Shear Hinge, Displacement Type
• For Columns: P-M2-M3 Curvature Hinge, Concrete Rotation Type Hinge
• For Shear Walls: Inelastic Section Hinge

Hinge translation is done the same way Inelastic materials are translated.  Similarly, the import process generates a warning to review the hinge properties in the ETABS model.  

The importing process will report the number of Hinge Properties imported from Perform3D model, also includes a message for every Hinge property.  This information is given in the import report as shown in the sample excerpt shown below:

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In a similar way, it will report the number of shells along with wall Hinge assignments. This information is also shown in the import report.

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LOADS

A load case is created in ETABS model for each load pattern Perform3D model. Loads from nodal load pattern and self-weight load pattern are assigned to joints in ETABS.  Loads from element load pattern are assigned to frame elements in ETABS.

ADDITIONAL MASSES

Additional masses are imported from Perform3D to ETABS. A sample excerpt of this import report section is shown below:

RIGID DIAPHRAGMS

When importing from Perform3D, If joint constraints are used in the Perform3D model for a floor, then ETABS will assign rigid diaphragm to all Joints at same storythat floor.  A sample excerpt of this import report section is shown below:

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