The dimensioning of prestressed members subjected to axial load and bending is governed by stress condition equations formulated for opposite extreme faces of section or by aid of design charts for different cases of members with uniform or non uniform prestress.

The direct method for computing leading dimensions of a section is feasible in case of pure flexure where necessary effective depth and breadth of compression face are controlled mainly by collapse limit states.

Bursting of prestressed concrete end block is one of criteria considered for ultimate limit state is bursting of end block, In erstwhile U.S.S.R as far back of 1930, problems were considered concerning formulation of a design concept to take into account variabilities inherent in materials of construction and design process and building construction.

F_k is characteristic strength of material which corresponds to 28 days cube strength compressive strength of concrete or tensile strength of tendons below which failures are not more than 5 percent.

In roadway slabs, construction joints shall be formed vertical and in true alignment and shear layers in construction joints should be constructed as shown in working site plans and in case of box girders webs, ses shear keys are normally shown on plans to full width.

The limit state of collapse may also be attained due to fatigue, vibrations, and corrosive environment impact as a consequence of explosions or earthquakes and disintegration due to fire or frost, a comprehensive and critical review of limit states design concepts embodied in various codes was presented in his reports reinforced concrete and prestressed concrete.

In structural members, ?_m is a maximum at tension face if h-x is sufficiently small for crack width at tension face not to exceed permissible limit of 0.3mm, it will not exceed limit anywhere, this is reason for smaller crack widths in slabs under service loads, provided thickness does not exceed about 200mm.

A new philosophy of design, termed limit state approach, which was incorporated in Russian code in 1954 basically limit state design is a method of designing structures based on statistical concept of safety and associated statistical probability of failure.

A successful design should not only satisfy requirements of safety against total collapse of structure due to various causes but also ensures that serviceability of structure is not impaired while resisting normal working loads.

When work is resumed surface of concrete previously placed should be thoroughly cleaned of dirt, scum, laitance, loosely projecting aggregates and or soft material using stiff wire brushes and surface should n be thoroughly soaked with clean water for two to three hours before furr concreting using a thin layer of cement slurry.