The present invention relates to a prefabricated, con¬ crete flooring slab provided with reinforcement steel, and intended to be provided after erection with a screed or the like of poured concrete, and implemented according to the preamble to Claim 1.

For the finished structure to function as a unit, where the cross-section of the poured concrete coacts in the deflected cross-section, so that the design height will be equal to the thickness of the prefabricated slab and the thickness of the poured concrete, measures must be taken so that shear forces occurring in one layer shall be transmitted to the other layer.

This has been achieved by the invention, according to which the prefabricated slab, which is provided at op¬ posing end portions with pit-like recesses in its upper side, these recesses having sides which are substantially perpendicular to the upper side and which can take up shear forces from the poured con¬ crete when the slab is loaded, is characterized in that arched reinforcing bars, which form lifting eyes, extend up from the bottom of the recesses to a height such that the intended poured concrete will cover the lifting eyes.

The shear forces are here substantially transmitted by compressive forces between the poured concrete and the sides of the recesses.

The shear forces can thus be transmitted in optional horizontal directions, which allows bending moments with optional direction of the vector to be utilized,

SUBSTITUTE SHEET

which may be the situation in the vicinity of suppor¬ ting beams coacting in the finished structure, a con¬ siderable reinforcement of the effect of the recesses on the shear forces being obtained by the inventive implementation.

The part of the lifting eyes situated nearest the bottom of the recesses are prefeably substantially perpendicular to the upper side of the slab for best coaction with pressure forces from parts of the sides of the recesses.

The inner ends of the lifting eyes can be fixed, e.g. welded, to the reinforcement of the slab, and earch recess is to advantage provided with two arched rein¬ forcing bars situated in two planes forming 90° with each other. Alternatively, they may be implemented as an integrated part of the longitudinal reinforcement of the slab.

Between therecesses, the poured concrete functions as a bar with constant normal force, which is less effec¬ tive than in continuos shear force transmission, but the differences are in general without importance.

The invention is more clearly explained in the follow¬ ing, with reference to the accompanying drawing sche¬ matically illustrating an embodiment of a prefabricated flooring slab in accordance with the invention, and where

Figure 1 is a plan of the slab;

Figure 2 is a side view of the slab in Figure 1; Figure 3 is a plan of a part of the slab illustrating a recess with two bars forming a lifting eye; and

SUBSTITUTESHEET

Figure 4 is a section along the line IV-IV in Figure 3.

Figures 1 and 2 illustrate the conventionally dimen¬ sioned, prefabricated flooring slab 1, which is pro¬ vided with two recesses 2 arranged at each end portion thereof, and in which recesses the lifting eyes 3 are upstanding. Concrete intended to be poured after erec¬ ting, the slab is denoted by the numeral 4 and indi¬ cated by a chain dotted line.

Figures 3 and 4 illustrate a recess 2 with two arched reinforcing steel bars 5, 6 upstanding in it such as to form a lifting eye. The legs 7,8 of the bars 5, 6 extend substantially perpendicular to the conventional reinforcement with longitudinal reinforcing steel bars 10 of the slab 1, outwardly bent end portions 11, 12 of the bars 5, 6 being welded or otherwise united with the bars 10.

SUBSTITUTE SHEET