FR2792354A1 - MASONRY STRUCTURE AND ASSOCIATED REINFORCEMENT METHOD - Google Patents

Abstract

The system may be used in old churches with stone vault ceilings (10) where the mortar between the stones (14) of the vault deteriorating. It pins the stones and holds them in position. Bores are drilled in each stone from the top surface (17) to withi short distance of the bottom surface (16) and a pin (19) is anchored in each bore. The top ends of the pins extend a considerable distance above the top surface of the vault. A synthetic mortar or cement (1 is poured onto the top surface of the vault, to a depth sufficient to cover the top ends of the pins. The layer of mortar is strong compression, when set, and extends into the spring of the arch (11) to transfer thrust to the wall of the building. The mix is chosen to give a coefficient of thermal expansion as near as possible equal to that of the stones of the vault.

Description

Masonry structure and associated reinforcement process.

  The present invention relates to the field of reinforcing masonry structures extending between two support points, for example a vault element or a cross member, comprising a

  plurality of parts mutually in compression.

  Over time, such structures are liable to deteriorate for various reasons, water infiltration causing degradation of the stones or bricks constituting the structure, compaction of the soil causing movement of the foundations of the building and its superstructures, modification of the building after its construction, etc. In a known manner, the restoration of a vault or an arch supporting arch in the event of cracking, degradation, deformation, can be carried out, either by grout of lime, the success of this process being random, or by replacement of the elements damaged or broken, requiring scaffolding or even a reconstruction of the structure. These processes impose heavy operating and implementation servitudes, in particular of time, of immobilization of the building or of the civil engineering structure, of cost, and do not make it possible to reinforce structures that are too stressed or

  degraded, reliably and safely, at a reasonable cost.

  In addition, in the case of vaults whose lower surface supports elements of great historical or artistic interest such as frescoes, paintings or sculptures, these methods do not allow them to be

fully preserve.

  The object of the present invention is to remedy the

  disadvantages of known methods.

  The object of the present invention is to propose a method for reinforcing a masonry structure which is easy, quick and inexpensive to use, while respecting the elements which should not be

modified by reinforcement.

  The reinforcement method according to the invention is intended for a masonry structure extending between at least two distinct bearing points and comprising a plurality of parts mutually in compression, each part being maintained by friction on the adjacent parts. A working element made of materials with expansion coefficients and elasticity coefficients close to those of the material constituting the masonry structure is added to an upper surface of the masonry structure, and secured to said masonry structure. This avoids any intervention on the lower surface of the structure which is generally the one of interest

historical or aesthetic.

  In one embodiment of the invention, the working element is secured to a roof of the masonry structure. We call "vault" a portion of vault bounded by edges or by ribs

occupying the place of edges.

  In another embodiment of the invention, the masonry structure comprising at least one arc formed of juxtaposed keys, the working element is secured to said arc. A vault of the

  masonry structure can be taken between the arch and the working element.

  In one embodiment of the invention, the keys are

  supported by the working element.

  In another embodiment of the invention, the compression stresses are distributed at least between the keys and the working element. They can be divided between the keyboards, the driver of the

  masonry structure and working element.

  In another embodiment of the invention, the compression stresses are distributed between a roof of the structure of

  masonry and the working element.

  Advantageously, the masonry structure and the working element are secured by means of needles sealed in drilled holes

  in the masonry structure and projecting into the working element.

  The masonry structure according to the invention extends between two support points and comprises a plurality of parts mutually in compression. Each part is maintained by friction on the adjacent parts. The structure includes a reinforcing element made of materials with coefficients of expansion and elasticity close to those of the material constituting the masonry structure. The reinforcing element is arranged on an upper surface of said structure.

  masonry and is secured to said masonry structure.

  A reinforced masonry structure is thus obtained without intervention on its lower surface and whose reinforcement is invisible

  on the side of this lower surface.

  Reinforcement is achieved by increasing the working section of the structure. Depending on the forces to be taken up by the working element and deformations of the original masonry structure, it can be provided that the working element has a variable section adapted to said efforts and thus allowing a reduction in the amount of material. used for the realization of the working element and therefore a reduction in cost. This increase in section

  working reduces stress on existing elements.

  One can even provide that the working element takes up all the efforts and supports the parts of the masonry structure. We can then provide a separation member between the working element and the existing structure, for example a sheet of felt, polyane or

  any other compatible material having sufficient resilience.

  If one wishes to increase the cohesion between the working element and the existing structure, one can provide a reinforcing veil extending on either side of the working element, for example over a certain width of a vault flat or vaulted, again to increase the inertia of the vault. The working element may be of width equal to that of an arc of the masonry structure or of width greater than that of

  the arch, in order to increase its transverse rigidity.

  Depending on the forces to be taken up and the deformation of the existing structure, the working element may be provided over the entire surface or over part of the surface of the existing structure, for example on certain arches of a vault, on portions of arch of a vault, console between a vault and a wall, etc. In one embodiment of the invention, a plurality of rods

  of reinforcement are embedded in the reinforcing element.

  In one embodiment of the invention, the reinforcing element is completed by a beam element, the element

  reinforcement and the beam element being integral.

  Advantageously, the reinforcing element is in the form of at least one flat beam secured to at least part of

  the said masonry structure, by means of tie rods.

  Advantageously, at least part of said structure of ma-

  çonnerie is provided with tie rods capable of distributing at least part of the load towards support points, each tie rod being secured to said

  part of the masonry structure and with a fulcrum.

  In one embodiment of the invention, a tie rod is sealed in a fulcrum provided with means for distributing the tensile forces exerted by said tie rod. The means for distributing a support point can be formed by at least one reinforcing bar

  substantially perpendicular to the tie secured to said support point.

  In one embodiment of the invention, a part of said masonry structure, subjected to transverse tensile forces is reinforced by crossed reinforcements to form a homogeneous tensile zone, which may include a part of an arc, a pillar part and a

  part of the intermediate blockage between lower and upper surfaces.

  We will choose to achieve the working element, a material having a Young's modulus more or less close to that of the existing structure depending on the charge transfer that we wish to achieve between the existing structure and the reinforcement. The working element can be produced in a mortar based on synthetic resin, for example epoxy resin, loaded or not, quartz, glass fibers, carbon fibers. This mortar must be able to be used under pressure

  atmospheric and have a grip without shrinkage.

  The needles for securing the pieces of the existing masonry structure and the working element are made from materials with good mechanical qualities and little sensitive to

  corrosion, for example glass fibers, carbon fibers, aramid fibers.

  These needles are sealed in the existing structure by means of a

  synthetic resin, for example epoxy, loaded or not with sand.

  The invention is perfectly suited to the reinforcement of flat arches, arches with semicircular arches, whether or not overstepped, with broken arcs, with arches in basket handle, with creeping arcs or even multi-lobed, resting on walls or pillars, and the reinforcement of a straight masonry structure of the cross or lintel type made in several working pieces

in compression.

  The present invention will be better understood on studying the

  detailed description of some embodiments taken as

  examples which are in no way limitative and illustrated by the appended drawings, in which: FIG. 1 is a schematic view of a cross vault of warheads; Figure 2 is a schematic view of a cross vault of warheads and secondary arches; Figure 3 is a partial sectional view of a cross vault of ribs according to III-III of Figure 1 reinforced according to a first embodiment of the invention; Figure 4 is a partial sectional view of a cross-ribbed vault according to IV-IV of Figure 1 reinforced according to the invention; Figure 5 is a partial sectional view along V-V of Figure 3; Figure 6 is a schematic sectional view of a reinforced flat roof according to a second embodiment of the invention; Figure 7 is a schematic top view of a reinforced flat roof according to a third embodiment of the invention; Figure 8 is a schematic sectional view of a planar structure of reinforced masonry according to a fourth embodiment of the invention; Figure 9 is a variant of Figure 3; Figure 10 is a schematic sectional view of a reinforced vault according to a fifth embodiment of the invention; and Figure 11 is a schematic top view of the vault of the

figure 10.

  In Figure 1, there is shown the principle of a cross vault of warheads comprising two arcs 1 and 2 mutually perpendicular and intersecting at their centers. The vault is limited on its edges 3 to 6, either by

  walls, either by double arches or former arches.

  In FIG. 2, it can be seen that secondary arcs 7 have been added, cooperating with ivy 8 and 9. The invention applies to all types of masonry structure resting on two support points and working in compression, for example a vault according to FIG. 1 or 2, or other types of vaults, sexpartite warhead vault, flat vault, or even straight structure working in compression, whatever the material in which the structure is made, bricks, different types of stones, granite, sandstone, limestone, etc. In Figure 3, we see a portion of stone vault 10 supported by a pedestal 1 1 surmounted by a sideboard wall 12. The portion of vault 10 comprises an arch 13 formed by a succession of keystones 14

  juxtaposed and whose separation planes pass through the axis of the arch 10.

  Each key 14 is put in compression between the neighboring keys and by said neighboring keys as well as by the load of the arch 10. The keys 14 are generally provided with mortar joints ensuring maximum friction between the various keys 14. The arch 10 comprises also a portion of vault delimited by arches and called vault 15. The vault 15 is of reduced thickness compared to

the arc 13 on which it rests.

  In most monuments and constructions, the lower surface 16 of the vault 10 is visible to the public, while the upper surface 17 is not, being covered with a floor or a roof. A working element 18, made of synthetic mortar, is poured onto the upper surface 17 of the vault in line with the arch 13. The working element 18 is firmly secured to each key 14 by means of needles 19, for example in resin

  epoxy loaded with glass fibers.

  The fitting of the working element 18 and of the needles 19 is carried out as follows. We start by clearing the upper surface 17 in line with the arc 13 from any annoying element such as a cracked coating or various waste. From the upper surface 17, at least one blind hole is dug in each key 14 14 in which a needle 19 is placed which is sealed with a composition of synthetic resin, for example epoxy. Part of the needle 19 is left projecting relative to the key 14. The depth of the blind hole and consequently the sealing length of the needle 19 are determined as a function of the load to be supported by said needle 19. very large load, we can

  provide several needles 19 per key 14.

  Then, one comes to cover the upper surface 17 in line with the arch 13 with a synthetic mortar to form the working element 18. The ends of the needles 19 projecting from the upper surface 17 are embedded in the synthetic mortar forming the working element 18. The section of the working element 18 is calculated as a function of the compression stresses to be supported. The working element 18 can be at

  variable section in order to adapt to variations in constraints.

  Thus, whatever the type of window to be reinforced, the working element 18 makes it possible to reduce the stresses to be borne by the existing elements. Depending on the type and state of deterioration of the vault, one can choose to share the compression stresses between the working element 18 and the arch 13 as can be seen in FIG. 3. The synthetic mortar intended to form the working element 18 is then poured directly onto the keyboards 14 to promote good adhesion between these two elements. Reinforcement reinforcements 27 can be embedded in the working element 18 to increase its mechanical characteristics. The frames 27 can be made of synthetic material, of the epoxy resin type reinforced with glass fibers or

carbon.

  In other cases, for example if the surface is severely degraded, the working element 18 must take up all the compression stresses and support each key 14 of the arch 13. There is then a separator 20 between the upper surface 17 and the working element 18 in order to prevent the arc 13 from supporting forces. The separator 20 can be presented

  in the form of a membrane, for example of felt or polyane.

  If the roof 15 still has good mechanical characteristics, one can choose to make it bear part of the stresses. As can be seen in Figure 5, the separator 20 is disposed between the working element 18 and each key 14 of the arch 13. There is on the upper surface 17 of the roof 15 and on the outer surface of the element working 18 a glass or laminate fabric forming a reinforcing web 21 and which extends over part or all of the roof 15 for its participation in the recovery of compression stresses. The reinforcing veil 21 can be produced by a succession of layers of glass fiber canvas and resin possibly including panels

honeycomb sandwich.

  To improve the joining of the roof 15 and the working element 18, it is also possible to provide stiffeners 22 arranged between a part of the reinforcement web 21 in line with the roof 15 and another part of the reinforcement web 21 in contact with the working element 18. The stiffeners 22 can be arranged at regular intervals, for example in a herringbone with a predetermined angle relative to the working element 18 and can be made of any inert material capable of withstanding

  tensile stresses, for example in aramid fibers.

  If we want the keys 14 also participate in the recovery of compression stresses, we will proceed to the installation of the element

  reinforcement 18 illustrated in FIG. 5, omitting the separator 20.

  Another type of vault is illustrated in FIG. 6. This vault 10

  is provided with a lower surface 16 of circular shape and a flat upper surface 17.

  The arch 10 is therefore of variable thickness, smaller at the center and stronger at the edges. Blind holes are then dug of suitable length to penetrate into the stones or bricks forming the lower surface 16 of the vault 10. These stones or bricks can be either keystones if the vault 10 is an arch, or vault elements if the vault 10 is a flat, non-ribbed roof. In these blind holes of variable depth, one comes to place and then seal needles 19 of suitable length to project beyond the upper surface 17, then one comes to pour the synthetic mortar forming the working element 18. Reinforcement reinforcements 27 can be embedded in the working element 18 to increase its

mechanical characteristics.

  In the embodiment illustrated in FIG. 7, the vault 10 is flat and of small thickness, the upper surface 17 being convex. As before, blind holes are dug in which needles are placed and sealed, not shown. The holes and the needles are short because of the small thickness of the vault 10. A large number are therefore provided in order to be able to ensure the necessary recovery of the compression stresses. Then, the synthetic mortar forming the working element 18 is poured. To ensure satisfactory rigidity in the working element 18, it is given a network shape, for example square, comprising longitudinal portions 23 parallel to each other and arcuate portions 24. It is possible, for a given arch, to vary locally the space separating the portions 23 and 24 of the working element 18, and / or their sections, to adapt their performance to the constraints to be taken up. To further increase the rigidity of the working element 18, it will be possible to advantageously use the reinforcing veil 21 illustrated in FIG. 5, which will make it possible to form a sort of shell for reinforcing the vault 10 and, in the

  extreme cases, arch support 10.

  In Figure 8, we see a masonry element of straight shape working in compression and comprising a plurality of keys 26 in the form of a bevel in order to ensure their mutual wedging and an operation similar to that of a vault. Each key 26 is pierced with one or more blind holes in which is disposed and sealed a needle 19 projecting above the key 26. A working element 18 is installed by grouting a synthetic mortar above said keys 26 and coats the free end of the needles 19. Preferably, a needle 19 is oriented with an angle between the angle of one of the

  faces of the bevel and the angle of the other face.

  The variant illustrated in FIG. 9 is similar to FIG. 3. A separator 20 is placed between the upper surface 17 of the arc 13 and the working element 18. Reinforcement reinforcements 27 are arranged in the working element 18 The reinforcements 27 have the form of straight bars

  rigid, substantially cylindrical in diameter on the order of 10 to 30 mm.

  There are several frames 27 so as to match the general shape of the working element 18 while maintaining the said frames 27 embedded in the working element 18 and intersecting in the cutting plane while

being shifted in depth.

  FIG. 10 illustrates a particular embodiment of the invention. A vault 28 covering a square-shaped piece is supported in its center by a pillar 29 and on its outer edges by walls 30. The upper surface 31 of the vault 28 is formed by the floor of the upper floor. The lower surface 32 is formed by arches and vaults. Between the upper surface 31 and the lower surface 32, or more precisely between the floor of the upper floor and the arches and vaults, a blocking 33, often heterogeneous, is arranged and used to fill the space and to load the vault 28. In this type of structure, there is often a deformation of the lower surface 32 and a

pillar settlement 29.

  A working element 34 in the form of one or more beams is arranged in one or more recesses dug in the upper surface 31 and extends into the walls 30. Needles, not shown, can be arranged to secure the working element 34 and / or the arches or vaults of the lower surface 32. Rods 35 are fixed at an upper end in the working element 34 and at a lower end in the pillar 29, for example at a height between the lower surface 32 and the upper surface 31. The tie rods 35 are distributed over all or part of the length of the working element 34. The tie rods 35 are formed in

  the same material as the needles and sealed in the same way.

  The portion 29a of the pillar 29 in which the lower ends of the tie rods 35 are fixed is subjected to significant tensile stresses in a horizontal plane. In addition, many tie rods 35 are fixed by sealing in the portion 29a. To take up these constraints, an armed complex 36 (FIG. 1) is formed in said portion 29a and in its vicinity. The reinforced complex 36 comprises a plurality of crossed rods 39 comprising glass, carbon or other fibers and having mechanical characteristics suitable for traction. The rods 39 are arranged in substantially horizontal holes drilled from the lower surface 32 at the portion 29a. The rods 39 are sealed in the same way as the needles, in the portion 29a, the blocking 33 and the arches or vaults of the lower surface 32. The reinforced complex 36 forms an area capable of withstanding transverse traction forces and of receiving the anchoring of

  the lower end of the tie rods 35.

  For the simplicity of the drawing in FIG. 11, the working element 34 and the tie rods 35 have not been shown. Tie rods 37, or tie rods, are fixed at an upper end in the walls 30 and at a lower end in the pillar 29 at the level of the reinforced complex 36. Holes are drilled in the walls 30. The upper end tie rods 37 is sealed over almost the entire thickness of the walls 30. The tie rods 37 are made of a material similar to that of needles and can reach sections of several square centimeters to take up significant efforts. The sealing is carried out in the same way as for the

  needles. Prestressing can be applied to tie rods 37.

  A wall 30 is a heterogeneous set of stones or bricks of various sizes and mortar. Its resistance to tensile forces

  exerted by a tie rod 37 is difficult to model and, a priori, weak.

  To avoid tearing away stones or bricks from said walls, provision is made to reinforce it in the following manner, prior to the installation of the

tie rods 37.

  One or more horizontal holes are drilled in the direction of the length of a wall 30 substantially perpendicular to the future tie rods 37. There are arranged and sealed there rods 38 of the same type as the tie rods 37 and of suitable dimensions. Prestressing can be applied to them. The area in which the rods 38 are arranged has a high cohesion. The forces exerted by the tie rods 37 can be distributed in the said zone without risk of tearing of stones or bricks. Thanks to the rods 38, a sort of horizontal beam is inserted inserted into each wall 30 and

  constituting a force distributor.

  The area in which the rods 38 are arranged is, in any case, stabilized by the mass of the parts of the walls 30 situated at a higher level and exerting a compressive stress. To further promote the distribution of forces, the number of tie rods 37 can be increased by reducing their unit cross-section and placing them in a fan shape from the

armed complex 36.

  Alternatively, one can design a reinforcement only based

  tie rods 37, rods 38 and reinforced complex 36.

  Thus, there is a strengthening process and a structure

  masonry structure extending between two support points and comprising a

  reinforcement element made with materials with coefficient of

  latation and elasticity close to those of the material constituting the masonry structure, secured to said masonry structure, at least part of said masonry structure being provided with tie rods capable of distributing at least part of the load towards support points, each tie being secured to said part of the masonry structure and with a support point. It is thus possible to reduce the compression load exerted on one support point and to transfer it to others. A tie rod can be sealed in a fulcrum provided with

  distributors of the tensile forces exerted by said tie rod.

  Thanks to the invention, a masonry structure is obtained which is reinforced considerably in so far as its stiffness is

  proportional to the cube of the height of its working section.

  The invention is perfectly suited to any structure whose lower surface must be protected, both during the work of

  reinforcement only at the end of these.

Claims (17)

  1. A method of reinforcing a masonry structure extending between at least two distinct support points and comprising a   plurality of parts mutually in compression, each part is held   by friction on the adjacent pieces, in which a working element is added to an upper surface of the masonry structure.   made from materials with expansion coefficients and elasticity   of those of the material constituting the masonry structure, and solida-   laughed at with the said masonry structure.   2. Method according to claim 1, wherein, the masonry structure comprising a roof, the working element is secured with the said vault.   3. Method according to claim 1, in which the masonry structure comprising at least one arch formed by juxtaposed keyboards,   the working element is secured to said arc.   4. The method of claim 3, wherein a roof of the   masonry structure is caught between the arch and the working element.   5. Method according to any one of claims 3 or 4,   in which the keys are supported by the working element.   6. Method according to any one of claims 3 or 4,   in which the compression stresses are distributed at least between   the keyboards and the working element.   7. The method of claim 6, wherein the compression stresses are distributed between the keyboards, the roof of the structure   masonry and the working element.   8. Method according to any one of claims 1 to 5, in   which the compression stresses are distributed between a roof of the   masonry structure and working element.   9. Method according to any one of the claims   previous, in which the masonry structure and the working element are secured by means of needles sealed in drilled holes   in the masonry structure and projecting into the working element.   10. Masonry structure (10) extending between two support points (11) and comprising a plurality of parts (14) mutually in compression, each part being maintained by friction on the adjacent parts, characterized in that it comprises a reinforcing element (18) produced with materials with coefficients of expansion and elasticity close to those of the material constituting the masonry structure, arranged on an upper surface (17) of the structure   masonry, and secured to said masonry structure.   11. Structure according to claim 10, characterized in that a plurality of reinforcing rods are embedded in the reinforcing element. 12. Structure according to claim 10 or 11, characterized in that the reinforcing element is completed by a beam element,   the reinforcing element and the beam element being integral.   13. Structure according to claim 10 or 11, characterized in that the reinforcing element is in the form of at least one planar beam secured to at least part of said structure   masonry, using tie rods.   14. Structure according to any one of claims 10 to 13,   characterized by the fact that at least part of said structure of ma-   çonnerie is provided with tie rods capable of distributing at least part of the load towards support points, each tie rod being secured to said   part of the masonry structure and with a fulcrum.   15. Structure according to claim 14, characterized in that a tie rod is sealed in a fulcrum provided with means of   distribution of the tensile forces exerted by said drawing.   16. Structure according to claim 15, characterized in that the means for distributing a fulcrum are formed by at least one reinforcing bar substantially perpendicular to the tie rod   secured to said support point.   17. Structure according to any one of claims 10 to 16,   characterized in that part of said masonry structure, subjected to transverse tensile forces is reinforced by   crossed reinforcements to form a homogeneous traction zone.