l m trying to model a prestressed beam with CFRP tendon. In abaqus I used trust element to model the prestressing tendon. when orthotropic material is defined， material orientation is needed. But when l assign material orientation to the tendon （which is modelled with trust element）, l still get the error bellow:

Anisotropic material properties without a local orientation system have been defined for 66 elements. Anisotropic material properties must be defined in a local orientation system. The elements are identified in element set ErrElemAnisotropicMaterial.

How to manage this?

THANKS！