This page describes possible reasons for the "The specified moving-load case assignments do not allow any nonzero response to be calculated" warning message that gets displayed in the log file when running moving load analysis.

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Reason 1: Load assignments required more lanes to be loaded than is the number of available lanes

This is the most common reason for the subject message. Figure 1 shows moving load case definition with 3 load assignments, each requiring at least one lane to be loaded. However, there are only two lanes available and therefore it is not possible to load at least one lane for each of the three assignments. A possible solution would to set the minimum number of lanes to be loaded to zero for each load assignment.

Figure 1: Moving load case definition with 2 lanes available, but the assignments requiring at least three lanes