1) Can a beam or a shell me made rigid for purposes of simulation?

2) Does the beam cross section have any significance in a simulation beyond determining its stiffness and mass?

3) Can I bond the beam joint to any size area on a shell, or must it be at least the projection of the beam cross section?

4) What is the function of the "for construction" diameter in a "pipe" beam?

Here are more details:  I needed a pivot for planar triangle, modeled as a shell, so I was kindly advised to use a beam with a "hinge" joint at one end and to bond that hinge to the appropriate area on the shell, defined by a split line.  Then I wanted to make the beam stiff enough without too large a cross section relative to my triangle -- apparently SW Premium (linear static simulation) doesn't allow a beam to be made rigid.  (I don't' even know if the beam cross section matters in a simulation except to determine the stiffness; but I needed to define the split line on the triangle somehow, both for bonding to the joint and for specification of a contact set to get accurate free-body forces/moments, so I used the beam cross section.)  In defining the "Weldments/Structural Member" for the beam, I chose "pipe" for circular symmetry and was offered only three choices, all to large.  The main puzzle here is that there are three diameters in a pipe cross section, OD, ID, and a smaller "for construction" circle of unknown function.  Can I edit all three of these diameters any way I want without disturbing the function of the beam (except for its stiffness and mass, of course)?