There are three types of members in prestressed concrete
TYPE 1 – Tension is not allowed; Cracking is not allowed.
TYPE 2 – Tension is allowed (within permissible stresses) ; Cracking is not allowed.
TYPE 3 – Tension is allowed; Cracking is allowed within permissible stresses.
Type 3 members are the most economical members because they allow cracking and thus use the elastic property of the materials.