Etteroppspenning av plattendekke

Abstract

In this master thesis, the use of post-tensioned lattice girder slabs has been investigated. By use of non-prestressed or pre-tensioned reinforcement, the usual span-width of lattice girder slabs are from 7 to 10.5 meters. In cases where parts of a floor system requires span-widths larger than10.5 m, lattice girder slabs will either not be used or supplemented with other types of concrete slabs.The latter can complicate matters as the thickness and properties will differ from the surrounding lattice girder slabs. It has thus been examined whether use of post-tensioning could increase this span-width, as well as how it will be dimensioned and excecuted. On the basis of Eurocode 2, a method has been mapped to calculate this slab type. Three separate cases has been calculated, of which one has been constructed and tested until failure. It consisted of 2 spans of 12 meters, with a total thickness of 270 mm. The results of this test indicates that this method of calculation can be considered conservative, as the test results significantly outperformed the expected results in terms of capacity and deflection.Through calculations of two further cases, it was determined that the slab type can support the span-widths for which it was required in the two cases, respectively 15 meters for a residential building and 12 meters for a basement parking structure.