truss element-axial hinge

[po0oya]

Hello
In my model a series of truss elements(pin-ended) should be connected to a beam-column element. should I define any hinges at the ends of each truss element? or does OpenSees always consider truss element as a pin-ended element ?. sorry I have another question too... I am expecting the truss element yields in tension (in pushover analysis), in other word axial hinge occurs at the middle of element. should I define nonlinear section similar to a beam column element? or is it sufficient to capture nonlinear behavior(axial hinge),by only defining nonlinear material for that? ... if strips can only yield in tension and don't have any capacity in compression, which type of material should I use for them. I want to define an elastic-perfectly plastic material only in tension.
last question! sorry! ... as mentioned above, I have a beam-column element which a series of truss elements should be connected to it. can I model beam-column as a continuous element by only two end nodes? if I should define beam-column element by a series of sub-elements which have short length , can I use nonlinear beam column element for those? does have any change in the number of integration points or other parameters ? because I have done this manner but I have encountered difficulties.
Thanks in advance.
thanks so much.

[fmk]

truss element has indeed zero rotational stifness .. if a model of only truss elements this measn either only create a model with translatinal dof or fix the rotational dof .. when including with beams, you need the rotational dof but any nodes with no beams framing in need to be fixed rotationally,

look at the multilinear material or place a steel01 material in series .. if divide beam use the nonlinnear displacement based element.

[po0oya]

Thanks so much Dr. McKenna for replying and your advance.
my model includes both beam and truss element. as I understood, because truss element has indeed zero rotational stiffness it dose't need to fix rotational dof. in other word because truss element can't carry any moment, therefor no moment is transmitted to other element (beam element). and I result in my model i don't need to fix any dof, is it true?
thanks in advance.

[fmk]

yes