Requires: Advanced Level

Envelope Feature

The Calculate Envelope Results feature is located on the Advanced Cases tab of the Load Case Manager. Note: This feature is not required for identifying extreme results, as reports can locate them, and design-checks handle this automatically. However, this feature is useful for calculating and storing extremes for time-history results, moving loads, and superposition combinations.

Viewing Envelope Result Cases

After enabling the Calculate Envelope Results feature in the Load Case Manager, the Envelope Results can be viewed in the Result View. In the Load Case section of the Home ribbon, select the Envelope Result Cases you want to display. Note: Both high and low extreme result cases can be selected. It is possible for the largest moment to be negative and occur in the low extremes result case. 

Envelope Moment Diagrams

Envelope results can be viewed graphically. To do so, select a member, then switch to the Member Graph tab. This displays plots of deflection, shear, and bending moment for the selected member, which can be customized to include or exclude specific items. Note: The Member Graph shows both the maximum (High Extreme) and minimum (Low Extreme) for the envelope. The Low Extreme is defined by the boundary with the lower magnitude, while the High Extreme corresponds to the boundary with the higher magnitude (absolute value). Viewing the results of a simple cantilever beam and comparing them to the Member Graph can clarify what is being displayed. You may notice sharp changes or steps in the plots, typically indicating where a different load case begins to control.

Envelope Reports

Envelope results can also be viewed in reports. Member reports for standard result cases, such as Member Forces or Member Displacement, can be used to view the High Extreme and Low Extreme cases. You have the option to view just the extreme results (i.e., the extreme results of the envelope) or a detailed table of all results along an element.

Note: Envelope results are calculated at discrete locations along the length of the member. The high and low extreme values at each location may come from different load cases. As a result, VisualAnalysis does not linearly interpolate between these result locations to produce a "summary" report or a report with more or fewer offsets than were calculated internally. The moment diagrams many not be smoothed and you may notice jumps or spikes in the values that would not typically appear in results for normal cases. To control the number of locations where envelope results are calculated, set an upper limit in Project Settings under Performance.