Prestress Loss

1 Bellefonte Nuclear Plant, Preliminary Safety Report 

2 Design of Prestressed Concrete Structures, Second Edition T. Y. Lin 

4a Preliminary Calculations Hoop Tendon - Prestress Loss EGB 

4b Reactor Containment - Friction Loss in Horz Tendon RWH 

For straight portion of Tendon use wobble only. For curved portion of Tendon use wobble and curve friction. When post tensioning from both sides, only half of the Tendon length is substituted for L.  

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Maliavine Atom Energoproject Russian Federation. Prestress losses in containments of WER 1000 Units. Joint Wano/OECD-NEA. Workshop, Civaux, Poitiers, France, 1997. 

Martinet, Guinet, Roussel, Granger. Prestress losses in NPP containments the EDF experience. Joint Wano/OECD-NEA. Workshop, Civaux, Poitiers, France, 1997. OECD-NEA Nuclear Regulation. Regulatory aspects of life extension and upgrading of MPPs. CNRA Special Issues, Meeting 2000 Report, January 2001. 

To determine the prestress losses for vertical Tendons in order to compute the required prestress force for design. 

AfsA VG = average value of steel prestress loss due to elastic shoetening. Li = 1.600ksi... 

The probable movements are obtained by obtaining the expected elastic properties and the normal anticipated loads. It is suggested that the extreme movements should be the maximum inward and outward movements that are obtained by allowing extreme variation in elastic properties, shrinkage, cyclic expansion, prestress loss, pressure and coefficient of expansion, as well as for non-symmetrical conditions in the vessel. In addition to these maximum values, associated minimum values should also be calculated. They are obtained by considering the vessel subjected to the same loadings as with the maximum values but with the non-symmetry effects taken as being in the opposite direction to those used for the maximum values. These minimum values are used in the calculation of the relative movements. 

This is considered first since it is not only involved directly as a measure of the vessels stiffness but also indirectly because of its effect on prestress losses. Experimental work [2, 8, 10, 17] carried out to obtain specific strain curves indicates that a suitable relationship exists between the elastic modulus and creep rates and, of course, how much softening effect is there due to temperature. 

Having assessed the variation of material, prestress and temperature properties for the vessel, it is now possible to compute the symmetrical absolute movements to the accuracy of the assumed concrete properties, values of prestress losses, etc. To obtain these movements, it is necessary first to decide which combination of the variations in vessel properties will yield the maximum and minimum vessel movements. 

For consideration of long-term durability and corrosion protection, the maximum allowable tensile stresses in the concrete at service loads, after allowance for all prestress losses, are of most interest. 

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