Dear Zeinah,

Your're in 2 or 3D modelisation FEA?

Arthur Germain Bilounga Engolo 3D

Just select only lines and issue an Lmesh command,after setting the element type and section type.

Normally you have to clear the elements before assigning new size or divisions of lines. Using commands in APDL, this is done by only 2/3-line code.

Alternatively, you can 'refine' the mesh in selected entities. see http://mae.uta.edu/~lawrence/ansys/h_refine/h_refine.htm