Ceiling formwork

Slab formwork is subject to high requirements in the construction industry. They have to withstand the high pressure of the concrete and at the same time have a low deflection to guarantee a flatness of the floor/slab. As part of a project, the deflections and the stresses in the slab table were determined for both a 30 cm and a 50 cm thick structure and the corresponding slab loads.
The stresses and deflection at the slab table were calculated using the finite element method with a shell model. The connection between the formlining and the slab table profiles was modeled with springs. This corresponds to the assumption that the formwork skin rests on the profiles.

The slab table is supported by four slab props. The stiffnesses of the props were represented by BEAM elements with a corresponding cross-section, which were fixed at the free end. The simulation showed a stress concentration in the area of the floor prop connection (see Figure 2). However, the calculated stresses are within the allowable range, thus demonstrating the structural integrity of the slab table.

The real deflection of the slab table was determined with a 3D measurement of concreted slabs. The deflection calculated in the FEM simulation showed good agreement with the measured values (deviation measurement to simulation ≈ 5%).

“Factually, therefore, the simulation is identical with reality!”  (www.ringer.at)


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Dr. Wolfgang Krach

+43 1 974 89 91-11