Design Method Of Post-tensioned Bonded Concrete Frame Structures

In this paper, according to the two-stage-working theory of prestressed steel tension, the formulas of normal section calculating for prestressed concrete members at two types of limit state are discussed. In consideration of the principle in which all of the prestressed concrete members in a same structure have to satisfy the two types of limit state, the design method on normal section of prestressed concrete members in statically indeterminate structures, taking account of the effect of the prestressing process, is presented to avoid the shortage in design method of post-tensioned bonded concrete frame structures at present. In the method, control equations for the crack resistance capacity of the normal section are established, so that the area of prestressed steel tension member may be obtained. Then the area of ordinary steel bar may be calculated with the equation of ultimate bending capacity on normal sections and structures in detail. The method avoids the problems of the secondary internal force produced by the prestress and the troublesome "passive design". The method makes design more simple, reasonable and economical, the new design mode of prestressed concrete structures in statically indeterminate structures is improved.