Thanks Modestas, i have completed the meshing and have a query now kindly find my new topic in the attached url
http://communities.bentley.com/products/structural/structural_analysis___design/f/5932/p/90116/256930.aspx#256930
does this create any problem in analysis or it cant be done in staad?
( i want the top surface of the plates to be flat, is it possible)
and if i want to live load on it then, what is the procedure?