External prestressing has given new hope for structures to rehabilitate and survive. Many buildings in mother earth are not used because they cannot take the designated load on them anymore, or their concrete strength is declining with time, or their owners want to change their function; therefore, the owners will apply extra loads more than the design loads, or they might decide to demolish one the structural elements in such buildings.
All these above-mentioned reasons are holding the structures from being functional. Applying External prestressing force, which gives a new level of structural integrity to existing structures, is a clever idea to resolve all the obstacles and make the buildings structurally sound.
The first step in structural analysis to determine structural integrity is finding the load path and strains in the structural elements. The load path determines the value of the straining actions on the two-way slabs design sections. Therefore, it controls the structural safety of the building.
Unlike traditional design methods, external prestressing gives a chance to the designer to control the load path by controlling the number of strands and the eccentricity. For example, in conventional reinforced concrete slabs, the designer assumes the slab will behave according to its rectangularity ratio; then, the designer starts designing the slab's columns and field strips. That means the concrete chooses to act according to its geometry. In Externally prestressed two-way slabs, the designer can control the load path by controlling the slab's deformations and, therefore, force the slabs to behave in a specific direction.
Two-way externally post-tensioned slabs could be a very practical yet economic structural solution for many buildings. Whether buildings are old or newly built externally, post-tensioning will work. If the building is old, two-way external post-tensioning can be used to rehabilitate the slabs, and if the building is new then the prestressing force can be incorporated to give the slabs of the building the required strength
For more information or zoom link, please email the Graduate Research School or phone (07) 4631 1088. The zoom links are included in the ReDTrain Bulletin.