Flat slabs are continuous
reinforced concrete plates with generally constant thickness, supported
directly by
regularly distributed columns. Over about a distance of 7~8 mm
between supports the prestressing of the slab is an efficient and economical
solution to prevent cracking and to increase its load
carrying capacity. The
post-tensioning of the slab is usually realized with using unbonded tendons.
Experiments with existing prestressed concrete floors have shown that with use
of traditional models the calculated value underestimate the real load bearing
capacity of these structures. Based on theoretical and experimental considerations
propositions for estimating the variation of the prestressing force during the
loading and different models to calculate the load carrying capacity of
prestressed post-tensioned concrete flat slabs with second order effects taken
into account are developed in this paper.