Modeling Process

This topic lays out a general process for creating a model using SAP. The intent is to demonstrate the interaction of the various commands available in SAP.

  1. Start a model by clicking the File menu > New Model command to access the New Model form. Choose to start the model from defaults (Initialize Model from Defaults with Units option) or from a previously defined model (Initialize Model From Previous File option).  Set the current units to those to be used most often in the model.

In general, we recommend using one of the SAP2000 templates to start a model whenever possible. The New Model form has a variety of template buttons that display common types of structures. Click the appropriate template button. After clicking any of the buttons except the Blank button or the Grid Only button, use the resulting form to specify the initial geometry for the model.

  1. With one of the templates displayed, click the + (plus) symbol beside the drop-down list(s) in the Section area to access forms to specify the frame sections or area sections used in the building model. Clicking the + (plus) symbol beside the Material drop-down lists on those forms will display forms for specifying the material properties, including a "quick material definition" feature that quickly applies standard material definitions.

    If the Grid Only button is used, use the commands on the Define menu to define the frame or area sections  and material properties needed for the model.

  2. Use the Design menu > {Aluminum; Cold-Formed Steel; Concrete; Steel Frame Design > View/Revise Preferences commands to specify the design code or modify any of the default preferences, which are generally consistent with the selected design code.

  3. If appropriate, use the Define menu commands to define cable sections, tendon sections, or solid properties to specify parameters for those objects in building the model.

  4. If appropriate, define link properties, joint constraints, hinge properties, or generalized displacements that can then be used to assign parameters for selected joints/points. Use the nonlinear link element to model base isolators and dampers.

  5. Use the Define menu > Load Patterns command to define static load patterns.

  6. If mass is used in the model,  use the Define menu > Mass Source command to specify the source of mass in the model.

Note: Mass is required if you are doing a modal analysis to determine mode shapes. It is also required to convert static nonlinear force-deformation results into the capacity spectrum ADRS format.

  1. Use the commands available on the Draw menu to draw frame, cable, tendon, area (poly or rectangular), point (special joints) and link objects as needed. We recommend assigning structural properties to objects as they are drawn using the Properties of Object form. The form can be used to assign structural properties, loads or masses. Also the line objects can be used as guidelines for snapping (see Snap To), which helps draw a model with accurate connectivity.

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    ote that all joints needed by the objects are automatically generated. No pre-definition of joints is required. Joints can be glued to a grid line. Moving the grid line will modify the location of all joints on the grid line and stretch or shrink all objects connected to those joints. Double click a grid line to display the Define Grid System Data form and accurately reposition the grid line. Also use that form to unlock the grid lines and drag and drop them on the screen to new locations.

  1. Use the Edit menu commands to modify and in some cases tweak the geometry of the model as needed. See the topics in the Edit folder of this Help for more information about those commands. Two commands, Extrude and Replicate, deserve special attention. The Edit menu > Extrude command is used to extrude points to frames/cables, line to areas, and areas to solids as well as convert lines to areas or lines and areas to solids and add solids between areas and areas between lines. The Edit menu > Replicate command is a powerful way of generating a large model from a small model when the objects and joints form a linear or radial pattern or are symmetrical about a plane.

  2. As appropriate, use the Define menu > Groups command to define group names and the Assign menu > Assign to Groups command to assign groups. A group is a collection of objects that is assigned a unique name. Groups may be used for many different purposes in SAP2000, including assigning properties or selecting objects for design. Each object may be part of as many groups as needed. Also, use the Define menu > Joint Patterns command to define a joint pattern and the Assign menu > Assign Joint Patterns command to assign joint patterns. A joint pattern is a set of scalar values defined at the joints. The specified named joint pattern can be referenced when assigning temperature or pressure loads to objects. This allows you to describe more complex distributions of temperature and pressure over the structure.

  3. Use the Assign menu commands to revise properties in your template model, if necessary, and to make additional assignments to template members as well as to any other members you might have drawn. The types of assignments that can be made include section properties, loads, masses, moment releases, partial fixity, and so forth. To make an assignment to an object, select the object then click the appropriate Assign menu command. See the topics in the Select book of this Help for information on the various options available in SAP2000 for selecting and deselecting objects.

Note:  Right clicking on an object will display an {Object Type} Information form (Point, Line, Area, Link, Solid). The three tabs on the forms identify the Assignments, Loads, and Location of the selected object. Left clicking in the cell associated with an assignment, load or coordinate may display a form that can be used to review and update the item. With a form displayed, clicking the F1 key on the keyboard will access the Help topic for that form. Also note that although several assignments can be made to an object, it is only necessary to make those assignments needed for your model.
 

If appropriate, use the Define menu > Define Moving Loads commands if a moving load analysis is to be conducted. Similarly, use the Define menu > Functions > Response Spectrum command or the Define menu > Functions > Time History command to define the required functions before defining the required load case.

  1. Use the Display menu > Show Tables command to review the model input. Alternatively, right click on an object to display assignment and load data on an object-by-object basis.

Use the View menu > Set Display Options command, or the Set Display Options button, to toggle on the display of various input items. Examples of the items that can be toggled on and off include labels, section properties, releases, springs, local axes, and the like.

  1. If desired, use the File menu > Print Tables command to print input data to a file or to the printer. Or use the File menu > Custom Report Writer command to generate the input data in various formats (.rtf, txt, html).

Alternatively, use the File menu > Export > Save SAP2000 MS Access Database mdb File command to save the input data in a database file that can be reviewed, modified and printed using Microsoft Access or the File menu > Export > Save SAP2000 MS Excel Spreadsheet xls File command to save the input data in a spreadsheet file that can be reviewed, modified and printed using Microsoft Excel.

  1. Use the Analyze menu > Set Analysis Options command to specify the model degrees of freedom.

  2. If your model has objects that require manual meshing, use the manual meshing options available using the Edit menu > Edit Lines > Divide Frames, Edit menu > Edit Areas > Divide Areas, or Edit menu > Divide Solids commands to mesh those objects.

  3. Use the Analyze menu > Run Analysis command to check the analysis status of the cases, delete results for cases that have already been run, set which cases are to be run and then run the analysis. When the analysis is complete, scroll through the text in the Analysis Window to check for any warnings or errors that might invalidate your analysis.

    When the analysis is complete, a deformed shape of the model will automatically display. If desired, animate the deformed shape and mode shape in 3D perspective by clicking the Start Animation button in the status bar at the bottom of the screen. Animate shell structures displaying stress contours with the corresponding deformed shapes in full in 3D perspective. While displaying mode shapes, the mode being displayed can be instantaneously changed with the '+/-' buttons that will appear at the bottom of the screen.

  1. Use the display features available on the Display menu to display analysis results on your model or on the screen in a tabular format. See the topics in the Display folder of this Help for more information about displaying results, such as forces and stresses (joints, links, frames/cables/tendons, shells, Asolids, solids, and planes), and loads (joints, links, frames/cables/tendons, areas and solids), as well as miscellaneous assignments (joints, links, frames/cables/tendons, areas, and solids), influence lines, plot functions, and static pushover curves.

Alternatively, use the Display menu > Show Tables command to display analysis results in tabular format.

  1. If desired, use the File menu > Print Tables  command to print output to a file or to the printer, or use the File menu > Custom Report Writer command to generate output in a variety of formats, including those compatible with Word, standard text editors, and .html editors.

Alternatively, use the File menu > Export > Export SAP2000 MS Access Database mdb File command to save the analysis output data in a database file that can be reviewed, modified and printed using Microsoft Access or File menu > Export > Export SAP2000 MS Excel Spreadsheet xls File command to save the analysis output data in a spreadsheet that can be reviewed, modified and printed using Microsoft Excel.

  1. If desired, use the commands available on the Design menu to run your model through one or more of the SAP2000 design postprocessors. See the Steel Frame Design Procedure, Concrete Frame Design Procedure or Aluminum Frame Design Procedure topics for more information about completing design.

Important:  Remember to save your model often!

TIP: The A to Z Problems provide step-by-step instructions for building a model. Doing a few of the problems may help you understand the relationship between the commands and how to apply the software to efficiently and easily complete your engineering tasks.