You can model the fiber member inside a beam element
To model them ideally, you can use solid modelling feature.
Although it is very difficult to model them in Staad considering the sold meshing but all you can do is import the meshed geometry in Staad from any other meshing software via 3dxf interface.
Now, such type of model which has two types of element can be analyzed in Staad.pro but please take a note that the analysis would be purely elastic.
If you intend to simulate the concrete beam where the non linear parabolic stress block is assumed and the tensile capacity of concrete is ignored, it wouldn't be possible to analyze such solid elements in Staad.pro.
To model them ideally, you can use solid modelling feature.
Although it is very difficult to model them in Staad considering the sold meshing but all you can do is import the meshed geometry in Staad from any other meshing software via 3dxf interface.
Now, such type of model which has two types of element can be analyzed in Staad.pro but please take a note that the analysis would be purely elastic.
If you intend to simulate the concrete beam where the non linear parabolic stress block is assumed and the tensile capacity of concrete is ignored, it wouldn't be possible to analyze such solid elements in Staad.pro.