Load tests

Long erection spans with strengthened lattice girders

Fig. 1 Erection of a precast floor plate with lattice girders.

Fig. 2 Lattice girders [2] with the relevant dimensions for the erection state.

Fig. 3 Precast floor plate as continuous beam in the erection state.

Fig. 4a Structural systems for load tests.

Fig. 5 Ultimate moment per lattice girder in the tests [6] and comparison with permissible moments [2].
Abb. 5 Bruchmomente je Gitterträger in den Versuchen [6] und Vergleich mit zulässigen Momenten [2].

Fig. 6 Ultimate shear forces in the tests [6] and comparison with permissible values [2].
Abb. 6 Bruchquerkräfte in den Versuchen [6] und Vergleich mit zulässigen Werten [2].

Fig. 7 Minimum support depth according to approval [2, 3] without additional edge yokes.

Fig. 8 Permissible erection spans for different lattice girder dimensions and spacing s_G, depending on the overall floor thickness.

Bild 4b

 Load tests performed on precast floor plates confirm erections spans of up to 6 m. To achieve these spans with high lattice girders, diagonals of 9-mm strength combined with upper chords of 16-mm thickness are required. Filigran-EV lattice girders were granted a technical approval for these spans.

Precast floor plates for floor systems consist of precast reinforced-concrete slabs of 5 cm thickness in which lattice girders are incorporated (Fig. 1) and an insitu concrete topping, which, when hardened, forms a structurally compo-site slab with the floor. In the erection state, the precast floor plates carry their own weight, the load imposed by the insitu concrete topping and the live load that occurs during its placement. Here, the flexurally rigid lattice girders increase the stiffness and the bearing capacity of the thin precast floor plate. The dimensions of the lattice girders, as...