The ultimate load carrying capacity of a statically determinate prestressed concrete structure is mainly controlled by flexural strength of a critical section in member and in contrast to this, ultimate load carrying capacity of an indeterminate prestressed concrete structure depends upon flexural strength of several critical sections and ir rotation capacity.

There are several methods for analyzing statically indeterminate prestressed structures to compute secondary moments that develop from prestressing structure and commonly used methods are based on principles of three moment orem, consistent deformation and tendon reaction and methods in b and c are also generally referred to as flexibility influence coefficient method and method of equivalent loads respectively and merits and demerits of se methods and ir suitability for given cases are outlined with help of examples.

The primary moment is apparent bending moment at a section in a statically indeterminate structure due to actual eccentricity of tendons from centroid axis and primary moment at every cross section of two span continuous beams is Pe as it is a hogging moment.

A reduction in number of anchorages in a continuous prestressed beam in comparison with a series of simply supported beam only one pair of post tensioning anchorages and a single stressing operation can serve several members.

In structures like portal frames with members in different directions, prestressing of transform results in an axial contraction, which in turn introduced tertiary moments in frames due to lateral displacement of junction of transform and column members.

The ultimate moment of resistance provided at any section of a member is not less than:
80% of moment at that section obtained from an elastic maximum moment diagram covering all appropriate combination of loads, elastic moment at any section in a member due to partial combination of loads shall not be reduced by more than 20 percent of numerically largest moment covering all appropriate combination of loads.

The tendon reaction method, suggested by Guyon, for analyzing statically indeterminate prestressed structure is based on principle of replacing tendon by an equivalent system of loads acting on concrete member which corresponds to reactions exerted by tendon concrete.

While a statically determinate structure is free to deform when prestressed a continuous structure cannot deform freely and however deflections should conform to law of consistent deformation.

The resultant moment at a section of an indeterminate prestressed structure is sum of primarily and secondary moments:
Resultant moment = (Determinate moment +Secondary moment).

Due to large deformations at critical sections in a statically indeterminate structure a concentration of curvature builds up over a few clearly defined short length of member, such as interior supports and midspan points of a continuous beam and se plastic zones are idealized as hinges at which a rotation is considered to take place.