Event Lumping Tolerance



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Event lumping tolerance is one of the Solution Control area/options that appear on the Nonlinear Parameters form. Access the Nonlinear Parameters form as follows:

  1. Click the Define menu > Analysis Cases command to display the Analysis Cases form.

  2. Click the Add New Case button or highlight a previously defined analysis case and click the Add Copy of Case or the Modify/Show Case button to display the Analysis Case Data form.

  3. Select Static from the Analysis Case Type drop-down list and the Nonlinear or Nonlinear Staged Construction option for the Analysis Type or Select Time History from the Analysis Case Type drop-down list and the Nonlinear and Direct Integration options for the Analysis Type and Time History Type.

  4. Click the "Nonlinear Parameters" Modify/Show button to display the Nonlinear Parameters form.

 

The nonlinear solution algorithm uses an event-to-event strategy for the frame hinges. A large number of hinges in a model could result in a huge number of solution steps. The event lumping tolerance option is used to group events to reduce solution time. The Event Lumping tolerance is used for both the Event Force Tolerance and the Event Deformation Tolerance, described below.

The Event Force Tolerance and the Event Deformation Tolerance are ratios that are used to determine when an event actually occurs for a hinge. Consider the figure, below, which shows the location of two hinges on their force-displacement plots. Hinge 1 has reached an event location. For hinge 2, if both the Event Force Tolerance and the Event Displacement Tolerance are met, the hinge is within event tolerance and it too will be treated as part of the event. In the figure, if the Force Tolerance divided by the Yield Force is less than the Event Force Tolerance specified in the Static Nonlinear Case Data and the Displacement Tolerance divided by the horizontal distance from B to C is less than the Displacement Event Tolerance specified in the Static Nonlinear Case Data, hinge 2 is treated as part of the event.

When determining the Force Tolerance Ratio, the denominator is always the yield force.

When determining the Displacement Tolerance Ratio, the denominator is the horizontal length of the portion of the force-displacement curve where the hinge is; hinge 2 is on the B-C portion of the curve. Thus we use the B-C horizontal length in the denominator of the Displacement Tolerance Ratio.

 

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