A kind of prestressed concrete beam with spiral broken line cables subjected to torsion is present based on the principle of generalized equivalent loads of prestress cables.

Little has been presented about the existing small curvature radius U-shaped prestressed tendon,whose practical elongation value and theoretical stretching elongation deviate greatly from each other.

In this paper,some problems about design of post-tensioned concrete structures are disussed,they are about the best balanced load,the main control facts of tendons and reinforcement amount,the calculating analysis of band beam in prestressed floor,and the concepts about the reasonal tendon shape in structure.