I am designing a hammerhead pier using the substructure module in LEAP Bridge Concrete. The geometry is a little odd...it's a hammerhead cap on a circular column. To compare the results for the cap design from the conventional sectional design & strut-and-tie, I have created two models. In one model the pier is defined as a hammerhead so that a strut-and-tie model can be defined for the cap, and the other model defines the pier as a multi-column with a tapered cap & round column (this is the actual pier configuration).
I generated the continuous beam live load reactions for both models in LEAP Bridge Concrete. In the hammerhead model the program generates six live load cases (which matches the number of cases shown in the theory section of the manual for auto live load generation). In the multi-column model the program only generates five live load cases.
I compared the generated forces from the two models and the values are all the same, but it appears that fifth case generated in the hammerhead model is not present in the multi-column model (i.e. LL1 through LL4 are the same for both models, LL5 in the hammerhead model is not generated in the multi-column model, and LL6 in the hammerhead matches LL5 in the multi-column).
Is there a reason that it would not generate the same number of cases for different pier types?