Transverse tensile stresses of considerable magnitude develop in transfer zone due to concentration of tendons at ends and se stresses are influenced by jacking and method of releasing tendons from prestressing beds.

At intermediate points along length of a beam, bond stress is resisted by adhesion, while in transfer zone tendons invariably slip and sink into concrete destroying most of adhesion.

By using transverse stress distribution designed anchorage zone in main reinforcement should withstand bursting tension and coincides with line of action of largest individual force on critical axis.

The transmission length prevailing at time of transfer does not remain constant but increases at a decreasing rate with time due to effect of creep and shrinkage of concrete, using radiographic strain measure techniques Evans and Robinson have conclusively shown that influence of passage of time is to increase transmission length and to move it bodily away from end of member.

The swelling of wire is only a few thousandth of a millimeter, but it neverless produces considerable radial pressures on concrete, giving rise to large frictional forces, general provisions in Indian code for transmission length are expressed in terms of diameter of wire, bar or strand, taking into considerations surface characteristics of tendons.

The transverse tensile stress is determined by empirical formula f_v = KM/b_wd²
f_v? Transverse tensile stress at centroid of end face, M ? Resulting bending moment between prestress force and internal prestress developed in concrete on centroidal axis, b_w = thickness of web, d = overall depth of beam, K = constant depending upon slope and distribution of tendons at ends.

While designing formwork, use of cap cables must be considered and space provided for fixing and handling of hydraulic jack must be sufficient especially at soffits of beam when cap cables are used.

Under normal ranges of values of transmission parameters, transmission length is likely to vary from 80 to 160?, several tests have been carried out by many investigators to determine transmission length and se methods can be classified into different categories depending upon principles under which solutions are obtained.

Shearing resistance is also known as dilatancy, it is considered in case of transmission of prestressing force from steel to concrete through bond, ACI code recommendations are based on investigations of Kaar and Hatson it includes both length required to develop effective prestress as also additional length over which strand must be bonded to concrete so that tensile stresses develop in strand at limit state of collapse of member.

? = 0.0235, cube strength of concrete is 30n/mm²,
Transmission length (L_t) = ((f_cu)^1/2 x 103/?)^1/2
= ((30)^1/2 x 10³/0.0235) = 485mm.