FR2606057A1 - REINFORCEMENT OF STRUCTURAL ELEMENTS BY INSERTING HIGH-STRENGTH PLATES - Google Patents

Abstract

A PROCESS FOR REINFORCING A WOODEN ELEMENT 1 INCLUDES THE FOLLOWING STEPS: EXCAVATING CAVITIES 4 IN THE AREAS TO BE REINFORCED WITH THE ELEMENT; INSERT IN THE SAID CAVITES REINFORCEMENT PLATES 5; FILL SUCH CAVITES WITH A CURABLE RESIN-BASED FILLING PRODUCT TO SOLIDARIZE THE SAME, THE SAME REINFORCEMENT PLATES ARE SUFFICIENTLY RESISTANT AND CORRECTLY DIMENSIONED TO BE ABLE TO RESTITUTE OR CONFERATE AFTER SOLIDARIZATION. IT MAY ALSO INCLUDE THE REPLACEMENT OF A MISSING PART 8 OF SUCH A WOODEN ELEMENT WITH A RESIN MORTAR, AND THE IMPREGNATION OF DEGRADED PARTS 3 OF SAID ELEMENT WITH A RESIN-BASED MATERIAL. THE SAME REINFORCEMENT PLATES 5 MAY BE OF WOOD, STEEL, METAL OR RIGID PLASTIC, DRILLED WITH HOLES 6, PROVIDED WITH POSITIONING AND SOLIDARIZING PLUGS, AND INCLUDING SUPPORT HEELS. APPLICATION IN PARTICULAR TO REHABILITATION AND RESTORATION OPERATIONS OF BUILDINGS.

Description

The present invention relates to a method for reinforcing elements in

wood,

  in particular of framework, such as beams.

  We can reinforce wooden beams and structural elements for different reasons: - weathering of the wood as a result of bad weather or attack by insect larvae, algae, fungi, micro-organisms (rots ). These alterations frequently affect for example the ends of embedded beams, in particular because of the humidity which can reign around the beam at the level of the embedding by absence of ventilation; 1 0 - appearance of abnormal loads which can lead to the breaking of fibers: overloading of floors, modification of the geometry of assemblies as a result of settlement of

foundations, etc ...

  French Patent No. 2,170,498 to BOUWECONOMISCH EN TECHNOLOOHISCH ADVIESBUREAU describes a method of reinforcing wooden beams in the region of their support by reinforcing rods driven into holes drilled in the wood and secured to the wood by a resin-based curable paste. This process has several drawbacks: on the one hand, it is difficult to size the reinforcing rods because we do not always know the direction and intensity of the forces to be taken up in a degraded beam, on the other

  apart from this process only concerns the reinforcement of beams at the level of their supports.

  Finally, reinforcing rods work especially in traction, and it is the degraded beam which must provide the additional mechanical resistance necessary for the resumption of the bending moments and the compressive forces. An object of the present invention is to propose a method of reinforcing wooden elements, in particular of framework, such as beams, without adding structural reinforcing parts to the exterior of said elements, and while preserving the original shape and size of these elements, as well as their appearance in most cases. Another object of the present invention is that said reinforcement is easily calculable, and that it is possible by using it to reinforce a wooden element both at the level of

  its supports only in other places, even over its entire length.

  According to the present invention, a method of reinforcing a wooden element, in particular a framework, comprises the following steps: - digging substantially flat cavities in the areas to be reinforced of the element Insert reinforcement plates in said cavities; - Fill said cavities with a curable resin-based filling product so as to secure said plates to the element, said reinforcement plates being sufficiently resistant and correctly sized to be able to restore or give the element the inertia desired after solidarity.

  The cavities are for example rebates or grooves dug in the wood.

  The resin product can be an epoxy resin, a grout or a resin mortar, which adheres strongly to both the wood and the material of the reinforcing plates, which can be metal, wood, plastic, or other

  sufficiently rigid and resistant material.

  According to an advantageous embodiment of the invention, the connection of the reinforcement plates with the grout or the resin mortar can be improved, either by perforating or perforating the reinforcement plates, or by equipping them with projections or reliefs such than

ankles or nipples.

  Still according to the invention, if the element comprises degraded zones, the degraded zones can be regenerated beforehand by impregnation by capillary action or by injection of resins, optionally solvent-based or recharged with a resin mortar.

  semi-flexible whose elasticity will have been adjusted according to that of the wood.

  Other characteristics and advantages of the present invention will appear better on

  reading of the following description given by way of nonlimiting examples of the forms

  possible embodiments of the invention, with reference to the attached drawings, which will do well

  understand how the invention can be realized.

  In the drawings: FIGS. La to ld are cross-sections in principle illustrating different stages of the reinforcement of an element according to an embodiment of the method of the invention; Figure 2 is a cross section in principle of a reinforced element according to another embodiment of the method of the invention; Figure 3 is a longitudinal section in principle of a rotten butt end of reinforced recessed beam according to the method of the invention; Figure 4a is a longitudinal section in principle of another end of a reinforced recessed beam according to the method of the invention; Figure 4b is a cross section in principle of the beam end of Figure 4a, along line XX; Figure 5 is a partial side view of an overloaded beam being reinforced according to the method of the invention; Figure 6 is a perspective view of a wooden beam to which has been restored

  initial resistance over its entire length thanks to the process.

  In Figure la, there is shown a beam I of rectangular section in cross section. A first zone 2 is healthy, while a second zone 3 is degraded by rotting. The broken lines show the initial shape of the beam. In FIG. 1 b, recesses in the form of grooves 4 have been dug in the beam. The grooves cross the degraded zone 3 and enter the healthy zone 2. FIG. 1c illustrates a later phase of the beam reinforcement: the degraded zone 3 has been impregnated with resin, and longitudinal reinforcement plates 5 have been placed in said grooves 4. The reinforcing plates 5 are pierced with holes 6. In FIG. 1d, the reinforcement is finished: a resin grout 7 was injected into said grooves 4 around the plates 5, and the shape of the beam was reconstituted by an addition of material in 8, which can be a resin mortar. The holes 6 have dimensions such that they are filled with resin grout during injection, which improves the joining of the reinforcement plates with

the rest of beam 1.

  Figure 2 is a cross section of a reinforced beam according to another variant of the method of the present invention. We recognize a beam 1 1, a healthy area 12, a degraded area 13 regenerated by impregnation of resin, a groove 14, which extends 1 5 longitudinally, and a reinforcing plate 15 inserted in said groove. This time, the reinforcing plate 15 is provided with pins or dowels 16 for securing to improve the joining of said plate to the rest of the beam 11. Said dowels also make it possible to position the reinforcement plate 15 in the front groove

  injection and setting of the resin grout.

  In Figure 3, there is shown in longitudinal section a buttress of recessed beam reinforced according to the method of the present invention. A wooden beam 21 is embedded in a load-bearing wall 20. A first zone 22 of the beam is healthy and a second zone 23 located near the wall is degraded, for example by decay. There is a lack of wood at the end of the beam, at the level of the embedding. According to the method of the invention, a reinforcing plate 25 has been introduced into a longitudinal groove not shown, but similar to those 4, 14 described previously with reference to FIGS. 1 and 2. The reinforcing plate extends in a part from the healthy zone 22, passes through the degraded zone 23 and protrudes from this second zone towards the outside, to the end of the beam as it originally appeared. A resin grout is then injected which fills all the voids around the reinforcement plates in the groove, said plates thus being embedded in the grout of

  resin, and between what remains of the beam and the wall 20, in the housing 28.

  In addition, the excess resin impregnates and strengthens the degraded or decomposed areas 23 of the wood, and gives them a resistance greater than their initial resistance. As before, the plate 25 can be provided with fixing holes or dowels 26 of

  joining and positioning.

  Figures 4a and 4b illustrate a variant of the process described with reference to the figure

  3. This time, the method of the invention is used to reconstruct a beam butt.

  The end of a wooden beam 31 supported by this end in a wall 30 is degraded and the support must be restored. Two longitudinal grooves 34 are dug in the beam and reinforcement plates 35 pierced with holes 36 are introduced into the grooves The reinforcement plates are here provided with bearing heels 40 at their lower part. The grooves start from a healthy zone 32 of the beam, cross the degraded zone 33 and extend towards the support up to the end of the beam as it appeared before its degradation. As before, a resin grout is injected into the grooves 34. It fills these grooves, permeates the degraded area 33 and replaces the missing material 38, here wood, at the end of the beam. A seal bottom 39 can be provided to limit the

1 0 resin overflows.

  The method of the invention can also be used to allow a beam to withstand forces for which it was not originally intended. This application of the process of the invention is illustrated in FIG. 5. Following an overload causing an excessive bending moment, a wooden beam 41 is cracked in the middle along surfaces defined by oblique lines 42. According to the invention, after having taken up the deflection of the beam by means of props 43, one or more longitudinal grooves 44 are hollowed out in the lower part of the beam 44 in each of which a reinforcing plate 45 is pierced with holes 46. After having produced injection holes 47, 48 which intersect the rupture cracks 42 in the beam 41, a resin-based product is injected into these holes. In this way, the resin product travels through the cracks and restores the monolithism of the beam. As before, the bloodletting is also

filled with resin.

  In the last example, illustrated in Figure 6, a wooden beam 51 8 meters long and 0.4 x 0.4 m2 in section, embedded at its ends to a depth of 0.40 m, was reinforced over its entire length by means of a metal plate 55 mm thick inserted into a groove 54 20 mm wide starting from the top of the beam and stopping 50 mm from the bottom of the beam. The plate 51 is pierced with securing holes 56. In this example, the beam has been restored to its initial strength after hardening of the resin injected into the groove 54 around the metal plate. It is easy to size the metal plate, because it was enough here to give it the same mechanical resistance as the wooden beam from the point of view of bending moments and cutting forces, the rest of the wooden beam being used here only for s to oppose the buckling of the game

  compressed from the metal plate, above its neutral axis.

  The method of the present invention is particularly applicable to the reinforcement of building structures, for example in the context of rehabilitation operations,

  building conversion or restoration.

Claims (9)

  1. Method for reinforcing a wooden element (1, 1 1, 21,31,41, 51), in particular a wooden element having degraded parts (3, 13, 23, 33), characterized in that it comprises the following stages: - digging substantially flat cavities (4, 14, 24, 34, 44, 54) in the areas to be reinforced of the element; - inserting into said cavities reinforcing plates (5, 15, 25, 35, 45, 55); - Fill said cavities (4, 14, 24, 34, 44, 54) with a curable resin-based filling product so as to secure said plates to the element, said reinforcing plates being sufficiently resistant and correctly 1 0 dimensioned to be able to restore or confer on said element the desired inertia after joining. 2. A method of strengthening a wooden element according to claim 1, characterized in that it further comprises replacing a missing part (8, 18, 28, 38) of said   wooden element with a refill material.   1 5 3. A method of reinforcing a wooden element according to claim 1 or claim 2, characterized in that it further comprises the impregnation of parts   degraded (3, 13, 23, 33) of said element by a resin-based product.   4. A method of reinforcing a wooden element according to any one of   previous claims, characterized in that said reinforcing plates are in   steel, metal, wood or rigid plastic.   5. A method of reinforcing a wooden element according to any one of   previous claims, characterized in that said reinforcing plates are   holes (6, 26, 36, 46, 56).   6. A method of reinforcing a wooden element according to any one of   previous claims, characterized in that said reinforcing plates are   provided with projections or reliefs such as dowels or pins for positioning and solidarity (16).   7. A method of reinforcing an element in bowls according to any one of   previous claims, characterized in that said reinforcing plates are provided with support heels (40).   8. A method of reinforcing a wooden element according to any one of   previous claims, characterized in that said resin product is a grout especially epoxy resin.   9. A method of reinforcing a wooden element according to any one of   previous claims, characterized in that said filling product is a mortar resin.