In a nonlinear system, some load cases do not converge. The load combinations, however, can easily be calculated. What is the cause of it?


When defining non-linearities, for example, failure of support under tension, it may happen that some load cases cannot be calculated. If these are loads that cannot exist without other stabilizing loads, solving the problem is simple: You can set the load cases to 'Not To Be Calculated'. As a result, only the load combinations are considered in the option 'Calculate All' of the calculation process. This is possible because, for example, some loads can never appear without having a self-weight.

In the attached example, it is clearly evident that the system would buckle in the load case wind, and thus no convergence is found. In contrast to this, it is possible to calculate the load combination in which self-weight and wind are combined without a problem because the self-weight stabilizes the system.


Load case Failure Nonlinear Horizontal Wind Seismicity Convergence criterion


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