For nonlinear static, nonlinear staged construction, and nonlinear direct-integration time-history load cases, you can choose whether or not to Use Event-to-Event Stepping from the Solution Control form.
Use Event-To-Event Stepping. If you select Yes, load steps will automatically be subdivided where significant changes occur in the stiffness of nonlinear elements. This causes a series of nearly linear steps to be taken, which can minimize deviation from equilibrium. For larger models, however, this may results in an excessive number of steps.
Event-Lumping Tolerance (Relative). This tolerance is used to group multiple events together. Effectively, the load increment calculated to reach the first event is increased by the tolerance to include other events that would occur soon afterward. Larger event tolerances reduce the number of event steps taken, but may increase the equilibrium unbalance or amount of iteration required.
Maximum Events per Step. This is the maximum number of events allowed per time step. Increasing this number may increase the accuracy of the analysis when iteration is not used, or lessen the need for iteration when used. On the other hand, allowing fewer events per time step may increase the speed of the analysis at the expense of more equilibrium error or iteration. If the specified Maximum Events per Step is exceeded in any time step during the analysis, the remainder of that particular time step is completed without further events; the analysis does not terminate. This parameter only applies to time-history analysis.
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:
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