On the current project I'm working on, I have several continuous joist runs with significant positive moments at the supports. See below for an example:
The supports here are concrete girders. I know that with the use of FEM, the deformations of the girder will effect the analysis results of the joists it is supporting, but from this moment diagram it seems as if the girder (support 2) is offering almost no support. I know that in reality this is not what is expected to happen and I know that I'm missing out on what the negative moment demand would actually be at the support. According to this, I only need 0.15in2 of top reinforcement at the support, which I know can't be true. I've read through the Concrete Analysis and Concrete Beam Manuals and haven't found a solution. Is there some criteria or setting that I can toggle to more accurately model the behavior of this type of case?
For reference: The girder is 30x25 and ~30 feet long. The joists are 6x25 and spaced at 5.5 ft. This particular joist run location is pointed out by the green arrow:
