I am trying to perform a nonlinear static analysis with SOL106. The material is linear elastic and only the geometric nonlinearities are present. In my model there are membrane elements (CTRIA3) and beam elements (CBEAM). I have connected the 3 translation dofs of the CTRIA3 nodes and CBEAM nodes that are coincident through CBUSH elements. The simulation does not even complete the first iteration. I receive the message of MAXIMUM RATIO OF MATRIX DIAGONAL TO FACTOR DIAGONAL to all elements. Here is a picture of the model (the pressure load are not shown, but are applied to all CTRIA3 elements with PLOAD4). In attachment there is also the NASTRAN input file. Can you help me figuring out the problem?