FR2698652A1 - Method of reinforcing timber floor on exposed beams without altering ceiling round them - includes steps of pouring reinforced concrete slab with pockets above beams part stressing filling pockets and loading for beam/slab bond with tension bolts - Google Patents

Abstract

The method includes steps of pouring a reinforced concrete slab (2) leaving blocked out pockets above the beams. The greater part of the beam lengths are then stressed before a compressive load is applied while the slab is tensioned (5) independent of the supports (9). The blocked out pockets are filled with concrete before loading to provide bond between the beams and slab. Two stops (7) are fixed to the shuttering (with tension bolts) for simultaneous loading of beams and slab. USE/ADVANTAGES - Economic solution for all problems associated with renovation of old buildings.

Description

METHOD AND DEVICES FOR REINFORCING WOOD FLOORS
The invention relates to a process implemented on the surface of floors with large loads and overloads without modifying the state of their underside.

The case frequently arises in particular during the rehabilitation of old buildings and with all the more acuteness that their floors have often already taken significant arrows.

To date when we want to reinforce a wooden floor while retaining its visible beams, we have the choice between two traditional solutions - we add beams inserted between the existing beams - we create a self-supporting floor over it.

But these solutions have, for one of the aesthetic drawbacks, for the other, a variation in the level of the floor which is often unacceptable, and for both of them, an often prohibitive cost.

The purpose of the present invention is to give designers and entrepreneurs the possibility of having recourse to an economical and all-purpose solution and to make available to them the equipment necessary for the implementation of said solution.

The process which is the subject of the invention, consisting in reinforcing a floor supported by exposed wooden beams without modifying the appearance of its ceiling, is characterized by
- pouring on the surface of a reinforced concrete slab leaving reservations directly above said beams
- before loading the floor, compressing said beams by exerting traction in said slab without affecting their supports
- the pouring of ons reservations making it possible to link beams and slabs.

A device for implementing the method comprises two buffers fixed to each beam, at least one of the two buffers having a jack allowing the simultaneous loading of the beam and the slab.

In a completed device, the two buffers are mounted on the box intended for the formwork of said reservation.

The following description will clearly understand the scope of the process and, thanks to the accompanying drawings by way of nonlimiting examples, the advantage of the devices which allow its implementation.

The example chosen is that of an old floor supported by visible main beams, with no visible secondary structure, the presence of the latter leading to particular suggestions in terms of devices for connecting the main beams to the slab which are not affected by the present invention.

Four figures give an illustration of the process and its implementing devices.

Figure 1 is a partial longitudinal section of a floor and
of the devices implemented.

Figures 2 to 4 show on cross sections the constraints of the various elements in various loading cases.

In Figure 1 we discover the embodiment and implementation of the various elements, the beam (1? Being supported by props (6) on the left part of the figure and free on the right part e:
- sheet metal bumpers (7) fixed to the beam (1) by lag screws (15) are hydraulically actuated (8) loaded by a torque wrench, but one could very well consider the use of means of setting hydraulic or pneumatic or other loads; we have planned to use two cylinders which must be loaded simultaneously but we can also be satisfied with a single cylinder provided that we can overcome the inevitable displacements of the beam (1? relative to the slab (2 ) and supports (
- reinforced parts (13) of the slab reinforced horizontally with beams so as to transmit the load from the jacks to the slab portions cast on each side of the longitudinal reservation (3);
- flexible material (14) of felt or expanded polystyrene type allowing the separation of the supports at any horizontal force which could result from a deformation of the edges of the slab
- formwork box (10) of said reservation (3) on the left-hand side of the figure, the continuity of which can be seen with the stopper, which naturally suggests their simultaneous implementation, the stopper being mounted at the ends of the boxes which fixing to be removed at the time of formwork: we can provide that the box is simply sliding inside the buffers
- connectors (12) on the right part of the figure fixed in the beam (1) after removal of the formwork box and which assumed connection of the concrete filling reservations (3) with the wooden beam to form a ladder beam composed of several materials and a concrete-wood floor.

On figuring 2 to 4 we see the various distributions of stresses in wood and in concrete at the various phases or mode of implementation and precisely because of this collaboration concrete wood,
FIG. 2 represents in horizontal hatching the compressive stress (4) of the cleared wooden beam (1) loading the jacks and in oblique hatching the tensile stresses (5) produced in the two parts of the separate slab (2) by the reservation (o) and their reinforcement (16).

FIG. 3 shows that, if the wooden beam (1) were stressed by the load of the slab and new overloads, the stresses of its extreme fibers (17) would reach an unacceptable value (18) in terms of the boom or even plane of the admissible stress of the bolsi
FIG. 4 shows on the contrary that a tensile stress (19) obtained by difference between the final stress (18) and the prestress (4) is acceptable while the compressive stress, which would have become on the other hand unacceptable due to the 'addition of the two compression stresses (18) and (4) in the absence of concrete-wood collaboration, practically vanishes due to the stress of the concrete with a maximum (21) in the upper fiber weak for the material.

We also note on this last figure the position of connector (12) which ensures the connection between the wooden beam (1) and the part (22) of the filling concrete forming the heel and the transmission of forces to the other part ( 23) in continuity with the previously poured slab (2).

Figures 1 to 4 are given as an indication but leave in trevoir for the first an embodiment and implementation of devices covered by the invention and for the other three how the prestressing of wood and concrete allows to radically modify the state of the final contrants in these two elements.

They show how easy the installation is and within the reach of any undertaking, provided that the prestressing forces are properly calculated.

 It is obvious that the present invention has been described for purely explanatory and in no way limitative and that any modification may be made to it, in particular at the level of technical equivalents, without however departing from its scope.

Claims (3)

1. A method of reinforcing the floor supported by exposed wooden beams (1) without modifying the appearance of its ceiling, characterized in that  - a reinforced concrete slab (2) is poured on the surface, making reservations (3) directly above said beams  - in most of their lengths, said beams are stressed before being loaded under compression (4) while the slab is stressed under tension (5) independently of the supports (9)  - said reservations are always poured before loading by ensuring the connection between beam and slab. 2. Device for implementing the method according to claim (1? Characterized in that it consists of two stops (7) fixed to each said beam (1), at least one stop having a jack (8) allowing the simultaneous loading of said beam and said slab. 3. Device according to claim 2 characterized in that said buffers are mounted on the boxes (10) for formwork of said reservations (3).