WO2006097962A1 - Process for manufacturing composite structural elements by gluing wood or its derivatives with concrete in the state of fresh mixture - Google Patents

Process for manufacturing composite structural elements by gluing wood or its derivatives with concrete in the state of fresh mixture Download PDF

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Publication number
WO2006097962A1
WO2006097962A1 PCT/IT2006/000152 IT2006000152W WO2006097962A1 WO 2006097962 A1 WO2006097962 A1 WO 2006097962A1 IT 2006000152 W IT2006000152 W IT 2006000152W WO 2006097962 A1 WO2006097962 A1 WO 2006097962A1
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WO
WIPO (PCT)
Prior art keywords
concrete
wood
casting
dan
adhesive
Prior art date
Application number
PCT/IT2006/000152
Other languages
French (fr)
Inventor
Giovanni Cenci
Original Assignee
Cenci, Sabrina
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Cenci, Sabrina filed Critical Cenci, Sabrina
Priority to EP06728485A priority Critical patent/EP1859109A1/en
Publication of WO2006097962A1 publication Critical patent/WO2006097962A1/en

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Classifications

    • EFIXED CONSTRUCTIONS
    • E04BUILDING
    • E04BGENERAL BUILDING CONSTRUCTIONS; WALLS, e.g. PARTITIONS; ROOFS; FLOORS; CEILINGS; INSULATION OR OTHER PROTECTION OF BUILDINGS
    • E04B5/00Floors; Floor construction with regard to insulation; Connections specially adapted therefor
    • E04B5/16Load-carrying floor structures wholly or partly cast or similarly formed in situ
    • E04B5/17Floor structures partly formed in situ
    • E04B5/18Floor structures partly formed in situ with stiffening ribs or other beam-like formations wholly cast between filling members
    • E04B5/21Cross-ribbed floors
    • EFIXED CONSTRUCTIONS
    • E04BUILDING
    • E04BGENERAL BUILDING CONSTRUCTIONS; WALLS, e.g. PARTITIONS; ROOFS; FLOORS; CEILINGS; INSULATION OR OTHER PROTECTION OF BUILDINGS
    • E04B5/00Floors; Floor construction with regard to insulation; Connections specially adapted therefor
    • E04B5/02Load-carrying floor structures formed substantially of prefabricated units
    • E04B5/04Load-carrying floor structures formed substantially of prefabricated units with beams or slabs of concrete or other stone-like material, e.g. asbestos cement
    • EFIXED CONSTRUCTIONS
    • E04BUILDING
    • E04BGENERAL BUILDING CONSTRUCTIONS; WALLS, e.g. PARTITIONS; ROOFS; FLOORS; CEILINGS; INSULATION OR OTHER PROTECTION OF BUILDINGS
    • E04B5/00Floors; Floor construction with regard to insulation; Connections specially adapted therefor
    • E04B5/16Load-carrying floor structures wholly or partly cast or similarly formed in situ
    • E04B5/17Floor structures partly formed in situ
    • E04B5/23Floor structures partly formed in situ with stiffening ribs or other beam-like formations wholly or partly prefabricated
    • EFIXED CONSTRUCTIONS
    • E04BUILDING
    • E04BGENERAL BUILDING CONSTRUCTIONS; WALLS, e.g. PARTITIONS; ROOFS; FLOORS; CEILINGS; INSULATION OR OTHER PROTECTION OF BUILDINGS
    • E04B5/00Floors; Floor construction with regard to insulation; Connections specially adapted therefor
    • E04B5/16Load-carrying floor structures wholly or partly cast or similarly formed in situ
    • E04B5/32Floor structures wholly cast in situ with or without form units or reinforcements
    • E04B5/36Floor structures wholly cast in situ with or without form units or reinforcements with form units as part of the floor
    • E04B5/38Floor structures wholly cast in situ with or without form units or reinforcements with form units as part of the floor with slab-shaped form units acting simultaneously as reinforcement; Form slabs with reinforcements extending laterally outside the element
    • EFIXED CONSTRUCTIONS
    • E04BUILDING
    • E04BGENERAL BUILDING CONSTRUCTIONS; WALLS, e.g. PARTITIONS; ROOFS; FLOORS; CEILINGS; INSULATION OR OTHER PROTECTION OF BUILDINGS
    • E04B5/00Floors; Floor construction with regard to insulation; Connections specially adapted therefor
    • E04B5/48Special adaptations of floors for incorporating ducts, e.g. for heating or ventilating
    • EFIXED CONSTRUCTIONS
    • E04BUILDING
    • E04BGENERAL BUILDING CONSTRUCTIONS; WALLS, e.g. PARTITIONS; ROOFS; FLOORS; CEILINGS; INSULATION OR OTHER PROTECTION OF BUILDINGS
    • E04B5/00Floors; Floor construction with regard to insulation; Connections specially adapted therefor
    • E04B5/16Load-carrying floor structures wholly or partly cast or similarly formed in situ
    • E04B5/17Floor structures partly formed in situ
    • E04B5/23Floor structures partly formed in situ with stiffening ribs or other beam-like formations wholly or partly prefabricated
    • E04B2005/232Floor structures partly formed in situ with stiffening ribs or other beam-like formations wholly or partly prefabricated with special provisions for connecting wooden stiffening ribs or other wooden beam-like formations to the concrete slab

Definitions

  • the present invention relates to a method for manufacturing any composite structural building element of wood or its derivatives and concrete such as floors and beams also provided with overhanging parts, pillars and partitions, etc., both manufactured in factory or on building yard, both delivered at or directly installed on site, and suitable both for new constructions or the static retrofitting of the already existing constructions, also in earthquake zones, as well as constructions able to withstand a considerable fire load, moreover also the static retrofitting and the functional recovery generally of buildings and particularly of sport facilities, a lot of buildings even of recent construction needing the improvement of their basic structure and the refurbishment of their side structures ⁇ and roof coverings .
  • a peculiar feature of the finding is to accomplish the integral connection between wood and concrete by the preliminary application to wood of an adhesive having a high resistance and molecular stability in time such as a two-component epoxy adhesive (or resin) . Furthermore, the ' following green-mixed, fibre- reinforced filling concrete casting is bound to the adhesive before the latter begins to cure.
  • connecting elements of metal or other materials between wood and concrete are not indispensable .
  • wood-concrete methods of construction will still be more basic in the near future for many reasons, including: wood is a material that can be renewed, has a reduced volume mass and can be easily worked; - the today methods, as it is the case of the laminated materials, allow large-size elements without any great defect to be provided;
  • - concrete is a good protection of wood if suitably waterproofed, especially in case of constructions exposed to weather such as footbridges and wharves;
  • - wood-concrete combinations allow considerable structural simplifications because of the natural self-carrying tendency of wood which can perform initially the function of supporting the concrete casting with which it will form one body after the maturation of the mixture;
  • the new method is more advantageous than other construction methods even because the energy cost due to weight, working and installation is reduced;
  • the present finding is a new, original solution over any known technique and any so far applied method as well, and is valid for the construction both of horizontal and vertical structures of any size without the need to use connecting elements of metal or other materials either to be embedded both into wood and concrete or fastened to one of them and embedded into the other one.
  • the wood-concrete integration and the hindrance to their mutual sliding are achieved by the application of a viscous adhesive to wood, thus providing a waterproof effect to the latter.
  • the adhesive is integral both with wood and concrete which is cast (poured and spread) under green-mix condition as the curing of the resin is still in the initial step, i.e. before the state of gel is reached. Accordingly, the gluing of concrete begins under its green-mix condition and sets upon maturation (setting) and remains as such all over the life time of the construction.
  • the method according to the invention allows not only to do without the known connectors but also the coating technique that uses bands, fibre tissues, and sheets of pre-impregnated fibres or steel.
  • the finding is able to match the resistance properties of structural elements in earthquake zones, as well as constructions that should withstand a considerable fire load. In those cases, the finding has a great importance not only in the new constructions but also in the recovery of the existing building estate.
  • Figure 1 is a detail of a composite element according to the invention.
  • Figure 2 is a three-dimensional view of the wooden portion only of the element of fig. 1;
  • Figure 3 is an enlarged detail of fig. 2;
  • Figure 4 is a three-dimensional view similar to fig. 2, in which the lightening elements and the application surfaces of the adhesive on the wooden portion are shown;
  • Figure 5 is an enlarged detail of fig. 4;
  • Figure 6 is a three-dimensional view similar to fig. 4, in which the concrete casting is partially shown;
  • Figure 7 is an enlarged detail of fig. 6;
  • Figure 8 is a three-dimensional view similar to fig. 6, in which an electrically welded mesh is shown;
  • Figure 9 is an enlarged detail of fig. 8.
  • Figure 10 is a three-dimensional view similar to fig. 6, in which rods or crosspieces are shown;
  • Figure 11 is an enlarged detail of fig. 10;
  • Figure 12 is a three-dimensional view similar to fig. 6, in which transversal frameworks are shown;
  • Figure 13 is an enlarged detail of fig. 12;
  • Figure 14 is a three-dimensional view similar to fig. 6, in which channels are formed in the thickness of the concrete;
  • Figure 15 is an enlarged detail of fig. 13;
  • Figure 16 is a three-dimensional view of a composite element according to the invention with an intermediate bearing, in which reinforcing irons in the zones of inversion of the bending moment are shown;
  • Figure 17 is an enlarged detail of fig. 16; ⁇
  • Figure 18 is a plan view of the structural element of fig. 4 together with a section view along line A-A;
  • Figure 19 is a longitudinal section of fig. 18- along line B-B together with shearing stress and bending moment diagrams;
  • Figure 20 shows a detail of the section A-A
  • Figure 21 shows a detail of section A-A fully consisting of wood
  • Figure 22 shows the gluing of wood and concrete by an epoxy adhesive to prevent the wood-concrete combination from sliding
  • Figure 23 shows enlargements of the sections along lines C-C and D-D;
  • Figure 24 is a plan view of the structural element of fig. 16 together with a section along line E-E and a longitudinal section along line F-F;
  • Figure 25 is the longitudinal section along line F-F of fig. 24 together with shearing stress and bending moment diagrams;
  • Figure 26 shows a detail of section E-E not only (above) and fully (below) consisting of wood, respectively;
  • Figure 27 is a plan view of the structural element similar to fig. 14 but provided with a further overhanging part, together with a section along line G-G;
  • Figure 28 is a longitudinal section along line H-H of fig. 27, together with shearing stress and bending moment diagrams;
  • Figure 29 shows a detail of section G-G fully consisting of wood.
  • an adhesive or resin 2 preferably a two-component, epoxy resin, is directly applied to the surface of wood 1, and the concrete casting 3 is poured during the "open time" of adhesive 2, i.e. the time in which the resin keeps its property of adhesion to materials.
  • Said adhesive 2 should have a limit workability duration (also called “pot life” or “open time”, i.e. period of time from the preparation during which an adhesive is usable for the following operations before setting or reticulation which modifies essentially the viscosity, adhesion capability, etc.) which is compatible with the middle-long operation time to carry out the concrete casting 3 during the pre- manufacturing or on yard.
  • a limit workability duration also called “pot life” or "open time”
  • adhesive 2 can cover as a whole one or more surfaces of wood 1 or be spread in parallel strips, orthogonal or oblique cross strips, or in lengths.
  • the surface of wood 1 on which adhesive 2 is spread must be clean and preferably dry (reduced humidity content) but not wet, otherwise a water film between wood and adhesive would be formed.
  • Adhesive 2 can also be enriched by metal fibres, synthetic fibres or any other kind of fibres and something else which is compatible and suitable to be embedded to improve the static performance and the safety over long time.
  • Concrete casting 3 having the designed resistance for example due to the reinforcement with steel, carbon, glass, synthetic, hybrid fibres, etc. is applied directly to wood surface 1 treated by adhesive 2 which is still in the state of "open time", i.e. in the time interval during which the curing is at its initial state and far from reaching the state of gel, in order to prevent cracking, to accomplish a considerable tensile strength, to increase the shearing stress strength,, and to improve ductility and toughness as well .
  • Lightened concrete 3 can also be used and there is no contraindication to the use of known measures such as fluidising additives, superfluidising agents, retardant agents, accelerators, aeration agents, antifreeze, expanders, water-repellants, etc., provided that they are compatible with adhesive 2 used.
  • lightening elements of polystyrene 5 or the like or hollow elements of fired bricks or wood-cement can certainly be inserted into the composite system.
  • the resistance of the inner ribs of concrete which are formed between lightening elements 5 should always be tested.
  • tubular, spherical or differently shaped elements can also be inserted into composite wood-concrete elements 1, 3 if this is compatible with the structure or necessary for any reason.
  • channels 6 for the passage of pipes, etc. can also be arranged in the thickness of concrete 3.
  • the method is also suitable for the reinforcement of the already existing floor and beams subject to thorough cleaning of the surfaces on which the adhesive will be applied and after having supported the wooden elements from the bottom or linked the same by provisional tie rods which are fastened to the high portion of the side walls or other overlying structural elements and held in their positions until concrete sets and achieves its carrying capability in combination with wood.
  • the method is also applicable to the recovery of old wooden structures of coverings such as trusses ands beams.
  • plate systems cab be provided by applying adhesive 2 and the following concrete casting 3 and, if necessary, by using also lightening elements.
  • the horizontal thrusts can also be born by the already existing wooden chains reinforced inside by glued steel bars (for example FeB44k for reinforced concrete or Dywidag steel bars 900(1000) .
  • the solution may also involve the additional use of connectors (e.g. stakes) to be inserted into the rafters of trusses and beams.
  • electrically welded meshes 8 having an anti-shrinkage function can also be inserted into concrete casting 3 or steel bars for reinforced concrete can be used at the bearings of combined wood-concrete beams when the static continuity is a necessity (figs. 16 and 17).
  • the disclosed method provides additional connectors in those cases where the static loads are greater and the static bearing capability must guarantee the maximum safety, for example, where conventional connectors, brackets, plates and anything else including coating techniques with fibre fabrics are used, and where the structural elements manufactured by the disclosed method have been too thinned during the construction work as it is the case of the unexpected passage of pipes 6 or the application of excessive loads.
  • both composite structural elements which are prefabricated in factory or on yard and composite structural elements directly manufactured upon installation can be provided according to the invention by the same advantages and procedures.
  • suitable casting containment side walls are used (fig. ⁇ ) .
  • An adhesive 2 for example a two-component epoxy resin, with a pot life compatible with the prefabrication time in factory or the construction time on yard is spread in strips or lengths on the whole surface or a portion thereof of the previously cleaned wooden structure 1.
  • the composite structural element is integrated by the concrete casting 3 having the resistance defined by the design calculation and carried out according to the invention within the "pot life" of adhesive 2.
  • concrete 3 can be reinforced with metal or synthetic fibres 4 and the mixture can be corrected by the addition of additives.
  • the composite element can be lightened by the insertion of synthetic material 5 and/or provided with channels 6 or other (figs. 14 and 15) .
  • surface cuts 9 can be made in a direction which is essentially transversal to the wood fibres 1 in order to receive steel rods 10 preferably having improved adherence or any other known materials (for example glass pr carbon fibre rods or wood lists or its derivatives) which are able to be glued upon manufacturing prefabricated wooden panels or during the application of- adhesive 2 in order to avoid or considerably reduce the capability of wood 1 of being deformed (swelling or shrinkage) in the transversal direction caused, for example, by the inside humidity variations (fig.. 10 and 11) .
  • steel rods 10 preferably having improved adherence or any other known materials (for example glass pr carbon fibre rods or wood lists or its derivatives) which are able to be glued upon manufacturing prefabricated wooden panels or during the application of- adhesive 2 in order to avoid or considerably reduce the capability of wood 1 of being deformed (swelling or shrinkage) in the transversal direction caused, for example, by the inside humidity variations (fig.. 10 and 11) .
  • small frameworks 11 with a reduced height able to be "embedded” into the thickness of the concrete casting 3, i.e. inside the transversal curbs formed between lightening blocks 5 can also be used by the same way.
  • said frameworks 11 help to improve the reciprocal cooperation between the longitudinal ribs of the whole composite structural element (figs. 12 and 13).
  • such a crossed-rib system (formed by the longitudinal ribs and the transversal rods) provides a grid which is characterized by a high rigidity in its plane to oppose any horizontal action such as the horizontal earthquake action.
  • the resistance conditions shall be tested by the allowable stress method or the limit operation method and/or the ultimate limit state method, with a particular attention to the sliding force on the gluing plane, the maximum shearing stress plane, and the test of the elastic behaviour as well.
  • Lightening inserts (blocks) 5 without any structural importance. Their weight is negligible. Any pipe 6 of any kind inserted in positions which is not prejudicial to the static (case not considered in the specific example) .
  • Steel bars 7 FeB44k to be used only for supporting "negative" moments, i.e. moments at the bearings, which take place in a continuos structure as it is the case for a continuous floor on several spans as well as an overhanging floor (balcony or cantilever roof) .
  • the weight of any integration bar FeB44k is generally negligible.
  • transversal curbs b4 of not necessarily reinforced mass concrete variable
  • d x ,i nf distance s4 of the lower floor surface from the neutral axis
  • dx,s u p,ci s distance s5 of the upper floor surface from the neutral axis
  • d x ,s u p,F e distance s6 of the integration irons, added for the negative moments, from the neutral axis;
  • test method provides that all materials are homogenised to wood.
  • a double-T section having concrete core, bottom wooden flanges, and upper concrete flanges is formed.
  • the longitudinal concrete curb between flooring 1 and the upper concrete bed 3 has been not considered in the calculation of Jx,id-
  • Tmax maximum shearing stress
  • Mi,x static moment referred to the neutral axis
  • Mi,unixepox static moment referred to the gluing plane
  • Jx,i d total ideal moment of inertia defined on the basis of the material homogenisation coefficients
  • the metal reinforcement for the transmission of the slipping forces between the concrete and wood portions is not necessary any longer because the slipping at the concrete-wood interface is totally compensated and transferred by the adhesive between the two materials.
  • FLOOR ON TWO BEARINGS (figures 18-23)
  • the invention provides that the floors on two bearings have in principle but not compulsorily longitudinal concrete ribs 3a without longitudinal metal reinforcement.
  • Metal bars FeB44k are inserted at the bearings only in overhanging floors and continuous floors on two or more spans to compensate the tensile stress in the upper portion of the floor.
  • Dead weight of the floor (wood+concrete, deducted the volume of polystyrene) : ⁇ (0.77 -0.06- 6.30) -600+[ (0.77 1 0.18 "6.30 ) +
  • Rck 300 i.e. the lowest stress among the structural materials used in the example.
  • Concrete is glued to wood at the longitudinal rib and also at the curbs formed at the transversal gap between the lightening elements. This allows the flooring to contribute to the statics all over its transversal width.

Abstract

A method of manufacturing composite structural elements of wood (1) and concrete (3) , characterized by the following steps: - positioning the wooden component (1); - applying a structural adhesive (2) able to glue wood (1) and concrete (3) to each other; - casting a green mixture of concrete (3) ; - waiting for the maturation time of the casting (3) ; - putting into operation of the composite structure thus obtained; said concrete (3) being cast in situ within the 'open time' (pot life) of the structural adhesive (2) , i.e. before the latter looses its adherence to wood (1) and concrete (3) .

Description

Process for manufacturing composite structural elements by gluing wood or its derivatives with concrete in the state of fresh mixture
The present invention relates to a method for manufacturing any composite structural building element of wood or its derivatives and concrete such as floors and beams also provided with overhanging parts, pillars and partitions, etc., both manufactured in factory or on building yard, both delivered at or directly installed on site, and suitable both for new constructions or the static retrofitting of the already existing constructions, also in earthquake zones, as well as constructions able to withstand a considerable fire load, moreover also the static retrofitting and the functional recovery generally of buildings and particularly of sport facilities, a lot of buildings even of recent construction needing the improvement of their basic structure and the refurbishment of their side structures < and roof coverings .
A peculiar feature of the finding is to accomplish the integral connection between wood and concrete by the preliminary application to wood of an adhesive having a high resistance and molecular stability in time such as a two-component epoxy adhesive (or resin) . Furthermore, the ' following green-mixed, fibre- reinforced filling concrete casting is bound to the adhesive before the latter begins to cure.
According to a further peculiar feature of the invention and unlike the known state of art, connecting elements of metal or other materials (wood, fibres, etc.) between wood and concrete are not indispensable .
One problem of the present wood-cement systems in which connecting elements consisting of stakes, screws and the like are mainly used consists in that inner localized or punctual forces arise.
Unlike such known solutions, if concrete is glued to wood according to the present invention a balanced diffusion of the stresses is obtained. Additionally, the use of fibre-reinforced concrete take advantage of its considerable omnidirectional tensile and shearing strengths . A further peculiar feature of the finding consists in that the fibre-reinforced concrete hampers the crosswise size variation of the wood by means of the adhesive which is considerably larger than the longitudinal size variation in case humidity variations takes place. The maintenance in time of the full structural functionality of the composite element is guaranteed by the adhesion of the resin to the surface wood fibre bundles which are made steady, in the crosswise direction owing to the fibre-reinforced concrete structure. GENERAL ASPECTS OF THE NEW METHOD
The use of wood for house, industrial, infrastructural buildings is growing wider with time.
The wider use of wood and its derivatives is due to more accurate choice of the raw materials and the quality certification as well as its mechanical resistance according to official standard. However, the methods used today for the construction of structural wooden elements and generally wooden buildings still feel the effects of obsolete methods. Only in recent years composite structural elements of wood and concrete connected to one another by connecting elements of steel, wood, fibres, etc. (stakes, screws and the like, even or three- dimensional frameworks, smooth or curved, pre-pierced or chequered sheets according to the structural or static needs) have been produced and constructed. Combined wood-concrete methods of construction will still be more basic in the near future for many reasons, including: wood is a material that can be renewed, has a reduced volume mass and can be easily worked; - the today methods, as it is the case of the laminated materials, allow large-size elements without any great defect to be provided;
- composite wood-cement systems can be easily provided and are now considered reliable from the structural point of view;
- concrete has an optimum compression strength and is compatible with wood as .far as the modulus of elasticity is concerned; however, concrete and wood should be made firmly integral with each other, because of the high tensile strength of the wooden fibres;
- concrete is a good protection of wood if suitably waterproofed, especially in case of constructions exposed to weather such as footbridges and wharves; - wood-concrete combinations allow considerable structural simplifications because of the natural self-carrying tendency of wood which can perform initially the function of supporting the concrete casting with which it will form one body after the maturation of the mixture;
- the new method is more advantageous than other construction methods even because the energy cost due to weight, working and installation is reduced;
- the use of composite wood-cement elements which are lighter than those conventional is advantageous as far as attainable spans, applicable loads, and elastic deformations is concerned;
- the part of wood on sight is an optimum aid under the action of fire of the environment involved because the static performance reduces gradually as the carbonisation penetrates wood; - wood-concrete combinations produce wooden portions of pleasant design and concrete portions of easy integration.
The present finding is a new, original solution over any known technique and any so far applied method as well, and is valid for the construction both of horizontal and vertical structures of any size without the need to use connecting elements of metal or other materials either to be embedded both into wood and concrete or fastened to one of them and embedded into the other one.
By the new method the wood-concrete integration and the hindrance to their mutual sliding are achieved by the application of a viscous adhesive to wood, thus providing a waterproof effect to the latter. It should be appreciated that the adhesive is integral both with wood and concrete which is cast (poured and spread) under green-mix condition as the curing of the resin is still in the initial step, i.e. before the state of gel is reached. Accordingly, the gluing of concrete begins under its green-mix condition and sets upon maturation (setting) and remains as such all over the life time of the construction.
As already mentioned, localized or punctual loads essentially arise in the conventional wood-cement systems which use stakes, screws or the like. The present finding, instead, glues concrete to wood, thus obtaining a balanced diffusion of the stresses, as well as employs fibre-reinforced concrete, thus taking advantage of its considerable omnidirectional tensile and shearing strengths. Concrete is able to be bound by the adhesive to the surface on sight of the resin bundles, and in case of a fibre-reinforced concrete, it hampers even the crosswise size variation of wood which is considerably wider than the longitudinal variation if remarkable humidity variations take place. As a result, the wood-concrete gluing keeps fully effective over the whole interface area.
Therefore, the method according to the invention allows not only to do without the known connectors but also the coating technique that uses bands, fibre tissues, and sheets of pre-impregnated fibres or steel.
According to the invention, there is provided to arrange suitable calibrated adhesives according to the peculiarity of the materials to be made integral with each other as well as the type of the composite structural elements, the environmental, operating conditions, and the surface area on which the adhesive should be applied, e.g. by brush, spatula, spray, etc. The finding is able to match the resistance properties of structural elements in earthquake zones, as well as constructions that should withstand a considerable fire load. In those cases, the finding has a great importance not only in the new constructions but also in the recovery of the existing building estate.
A better understanding of the finding will result from the following detailed description with reference to the accompanying drawings that show a preferred embodiment thereof and a simplified variation only by way of a not limiting example. In the drawings :
Figure 1 is a detail of a composite element according to the invention;
Figure 2 is a three-dimensional view of the wooden portion only of the element of fig. 1;
Figure 3 is an enlarged detail of fig. 2;
Figure 4 is a three-dimensional view similar to fig. 2, in which the lightening elements and the application surfaces of the adhesive on the wooden portion are shown;
Figure 5 is an enlarged detail of fig. 4;
Figure 6 is a three-dimensional view similar to fig. 4, in which the concrete casting is partially shown; Figure 7 is an enlarged detail of fig. 6;
Figure 8 is a three-dimensional view similar to fig. 6, in which an electrically welded mesh is shown;
Figure 9 is an enlarged detail of fig. 8;
Figure 10 is a three-dimensional view similar to fig. 6, in which rods or crosspieces are shown;
Figure 11 is an enlarged detail of fig. 10;
Figure 12 is a three-dimensional view similar to fig. 6, in which transversal frameworks are shown;
Figure 13 is an enlarged detail of fig. 12;
Figure 14 is a three-dimensional view similar to fig. 6, in which channels are formed in the thickness of the concrete;
Figure 15 is an enlarged detail of fig. 13;
Figure 16 is a three-dimensional view of a composite element according to the invention with an intermediate bearing, in which reinforcing irons in the zones of inversion of the bending moment are shown;
Figure 17 is an enlarged detail of fig. 16;
Figure 18 is a plan view of the structural element of fig. 4 together with a section view along line A-A;
Figure 19 is a longitudinal section of fig. 18- along line B-B together with shearing stress and bending moment diagrams;
Figure 20 shows a detail of the section A-A;
Figure 21 shows a detail of section A-A fully consisting of wood;
Figure 22 shows the gluing of wood and concrete by an epoxy adhesive to prevent the wood-concrete combination from sliding;
Figure 23 shows enlargements of the sections along lines C-C and D-D;
Figure 24 is a plan view of the structural element of fig. 16 together with a section along line E-E and a longitudinal section along line F-F;
Figure 25 is the longitudinal section along line F-F of fig. 24 together with shearing stress and bending moment diagrams;
Figure 26 shows a detail of section E-E not only (above) and fully (below) consisting of wood, respectively;
Figure 27 is a plan view of the structural element similar to fig. 14 but provided with a further overhanging part, together with a section along line G-G;
Figure 28 is a longitudinal section along line H-H of fig. 27, together with shearing stress and bending moment diagrams; and
Figure 29 shows a detail of section G-G fully consisting of wood.
DESCRIPTION OF THE METHOD
According to the invention an adhesive or resin 2, preferably a two-component, epoxy resin, is directly applied to the surface of wood 1, and the concrete casting 3 is poured during the "open time" of adhesive 2, i.e. the time in which the resin keeps its property of adhesion to materials.
Said adhesive 2 should have a limit workability duration (also called "pot life" or "open time", i.e. period of time from the preparation during which an adhesive is usable for the following operations before setting or reticulation which modifies essentially the viscosity, adhesion capability, etc.) which is compatible with the middle-long operation time to carry out the concrete casting 3 during the pre- manufacturing or on yard. According to the static requirements adhesive 2 can cover as a whole one or more surfaces of wood 1 or be spread in parallel strips, orthogonal or oblique cross strips, or in lengths.
The surface of wood 1 on which adhesive 2 is spread must be clean and preferably dry (reduced humidity content) but not wet, otherwise a water film between wood and adhesive would be formed.
It is possible to operate on simple cut or planed surfaces as well as to make the wood surface rough or to carve, to recess, to mark it and anything else if this can be useful to improve the adherence of adhesive 2.
Adhesive 2 can also be enriched by metal fibres, synthetic fibres or any other kind of fibres and something else which is compatible and suitable to be embedded to improve the static performance and the safety over long time.
Concrete casting 3 having the designed resistance, for example due to the reinforcement with steel, carbon, glass, synthetic, hybrid fibres, etc. is applied directly to wood surface 1 treated by adhesive 2 which is still in the state of "open time", i.e. in the time interval during which the curing is at its initial state and far from reaching the state of gel, in order to prevent cracking, to accomplish a considerable tensile strength, to increase the shearing stress strength,, and to improve ductility and toughness as well .
Lightened concrete 3 can also be used and there is no contraindication to the use of known measures such as fluidising additives, superfluidising agents, retardant agents, accelerators, aeration agents, antifreeze, expanders, water-repellants, etc., provided that they are compatible with adhesive 2 used.
On condition that an accurate design is provided with calculations and testing of the surface to be glued between wood 1 and concrete 3, lightening elements of polystyrene 5 or the like or hollow elements of fired bricks or wood-cement can certainly be inserted into the composite system. Of course, the resistance of the inner ribs of concrete which are formed between lightening elements 5 should always be tested. According to the invention, tubular, spherical or differently shaped elements can also be inserted into composite wood-concrete elements 1, 3 if this is compatible with the structure or necessary for any reason. For example, channels 6 for the passage of pipes, etc. can also be arranged in the thickness of concrete 3. It is fully clear that the system disclosed above can also be applied to composite elements of the sandwich type both arranged for horizontal (floors) or vertical (walls and beams) installations as well as for the construction of floors with crossed wooden plot and in any case without any limitation to the mode of use and destination, i.e. the general production or construction of composite structural elements of wood and its derivatives and preferably fibre-reinforced concrete that are made integral with each other by the use of adhesive. The method is also suitable for the reinforcement of the already existing floor and beams subject to thorough cleaning of the surfaces on which the adhesive will be applied and after having supported the wooden elements from the bottom or linked the same by provisional tie rods which are fastened to the high portion of the side walls or other overlying structural elements and held in their positions until concrete sets and achieves its carrying capability in combination with wood.
The method is also applicable to the recovery of old wooden structures of coverings such as trusses ands beams. After the cleaning of the upper surfaces of the wooden elements on the pitch plane or near such plane and the covering by staves with a suitable thickness and quality (for example KVH rods) , plate systems cab be provided by applying adhesive 2 and the following concrete casting 3 and, if necessary, by using also lightening elements. In case of trusses, the horizontal thrusts can also be born by the already existing wooden chains reinforced inside by glued steel bars (for example FeB44k for reinforced concrete or Dywidag steel bars 900(1000) . The solution may also involve the additional use of connectors (e.g. stakes) to be inserted into the rafters of trusses and beams. The influence of the humidity variations to systems consisting of woods and fibre-reinforced concrete connected to each other by adhesive has been already faced. Moreover, the variation of the humidity content in the wood barely affects the size variations in the longitudinal direction (parallel to fibres) . Therefore, the disclosed method can advantageously be used also for not yet dried wood trunks or so-called "Fiume" or "Trieste" beams by particular measures and additional connecting means crossing the wooden fibres. Thus, in case of natural disasters, provisional bridges can be quickly made by using very common materials available on site.
According to the finding, electrically welded meshes 8 having an anti-shrinkage function (figs. 8 and 9) can also be inserted into concrete casting 3 or steel bars for reinforced concrete can be used at the bearings of combined wood-concrete beams when the static continuity is a necessity (figs. 16 and 17). Likewise, in case of both new constructions and renovation or structure refurbishment the disclosed method provides additional connectors in those cases where the static loads are greater and the static bearing capability must guarantee the maximum safety, for example, where conventional connectors, brackets, plates and anything else including coating techniques with fibre fabrics are used, and where the structural elements manufactured by the disclosed method have been too thinned during the construction work as it is the case of the unexpected passage of pipes 6 or the application of excessive loads.
With reference to the accompanying drawings, both composite structural elements which are prefabricated in factory or on yard and composite structural elements directly manufactured upon installation can be provided according to the invention by the same advantages and procedures. In case of prefabricated composite elements, suitable casting containment side walls are used (fig. β) . An adhesive 2, for example a two-component epoxy resin, with a pot life compatible with the prefabrication time in factory or the construction time on yard is spread in strips or lengths on the whole surface or a portion thereof of the previously cleaned wooden structure 1. The composite structural element is integrated by the concrete casting 3 having the resistance defined by the design calculation and carried out according to the invention within the "pot life" of adhesive 2.
In case of necessity, concrete 3 can be reinforced with metal or synthetic fibres 4 and the mixture can be corrected by the addition of additives. According to the design calculation, the composite element can be lightened by the insertion of synthetic material 5 and/or provided with channels 6 or other (figs. 14 and 15) . In addition to the well known electrically welded mesh 8 having an anti-shrinkage function, surface cuts 9 can be made in a direction which is essentially transversal to the wood fibres 1 in order to receive steel rods 10 preferably having improved adherence or any other known materials (for example glass pr carbon fibre rods or wood lists or its derivatives) which are able to be glued upon manufacturing prefabricated wooden panels or during the application of- adhesive 2 in order to avoid or considerably reduce the capability of wood 1 of being deformed (swelling or shrinkage) in the transversal direction caused, for example, by the inside humidity variations (fig.. 10 and 11) . As an alternative to said transversal rods 10, small frameworks 11 with a reduced height able to be "embedded" into the thickness of the concrete casting 3, i.e. inside the transversal curbs formed between lightening blocks 5 can also be used by the same way. Of course, in addition to avoid or reduce drastically the capability of wood 1 of being deformed in the transversal direction, in case of concentrated loads said frameworks 11 help to improve the reciprocal cooperation between the longitudinal ribs of the whole composite structural element (figs. 12 and 13). Furthermore, such a crossed-rib system (formed by the longitudinal ribs and the transversal rods) provides a grid which is characterized by a high rigidity in its plane to oppose any horizontal action such as the horizontal earthquake action.
At last, in case continuous composite structural elements have to be provided on one or more intermediate bearings (figs. 16 and 17), integration metal frameworks and/or -straight and/or curved- reinforcement bars 7 can be inserted at those bearings to distribute the stresses produced by the inversions of bending moment which are present, as known, at such intermediate bearings .
As far as the general static conditions is concerned it is evident that the usual static calculation and testing regarding the knowledge of the construction theory and statics must be applied. To sum up, generally and not necessarily in a thorough way, the homogenisation coefficients of the basic materials referred to the respective modulus of elasticity will first of all be defined. Next, the ideal geometric parameters (areas, inertia, centre of gravity, axes, static moments, etc.) of the examined construction shall be defined. Then, on the basis of the geometry of the structural element, the statics, the applied loads, etc. the resistance conditions shall be tested by the allowable stress method or the limit operation method and/or the ultimate limit state method, with a particular attention to the sliding force on the gluing plane, the maximum shearing stress plane, and the test of the elastic behaviour as well. EXAMPLES OF CALCULATION
Three examples of calculation are shown below, each referring to a composite structural element consisting of a floor made by the method according to the present invention relative to:
- floor with two bearings; one span (figs. 18-24);
- continuous floor on three bearings: two like spans (figs. 24-26); - floor on two bearings and one overhanging part: one span with overhanging part (figs. 27-29).
PERFORMANCE OF THE MATERIALS USED IN THE EXAMPLES :
Wooden flooring 1 KVH Select (Konstruktions VoIl HoIz) , class MSlO: - Allowable bending sigma// 100 daN/cm2
- Allowable tensile stress sigma// 70 daN/cm2
- Allowable compression sigma// 85 daN/cm2
- Allowable longitudinal tau// 9 daN/cm2
- Allowable transversal tauj_ 12 daN/cm2 - Modulus of elasticity E// 100,000 daN/cm2
- Volume mass 600 daN/cm2 In the example:
Two-component, epoxy adhesive 2, type ϋnixepox® 6226:
- Specific gravity at 200C (ASTM D 792-66) 1.45 daN/dm3 - Stoichiometric ratio by volume A:B=2:1
- Pot life at 200C 150 cc (ERL 13-70) 140÷170 minutes
- Open time for concrete casting ad 1O0C about 6 hours
- Open time for concrete casting ad 2O0C about 4 hours
- Open time for concrete casting ad 3O0C about 2 hours - Max. vitreous transition (ASTM D 3418) 65°C
- Tearing adhesion on wood (red deal) (ASTM D 1870) : crack type 100% wood cohesion - Tearing adhesion on concrete (ASTM D 1870) : crack type 100% concrete cohesion
- Shrinkage (ASTM D 2566) about 0.35xl0~3%
- Unit compression breaking load 800 daN/cm2 - Unit compression breaking load 500 daN/cm2
- Unit ultimate tensile stress 400 daN/cm2
- Unit ultimate shearing stress 400 daN/cm2
- Compression modulus of elasticity E
(ASTM D 695) 72,000 daN/cm2 Concrete 3 Rck 300:
- longitudinal ribs 3a of generally not reinforced concrete;
- transversal curbs 3b of generally not reinforced concrete; - bed (cope) 3c of concrete possibly reinforced with electrically welded mesh;
- portion of the bed 3d (cope) of concrete for the testing calculation according to the expression 3d=[3a+2. ("s3". 5 times) ] .s3; - ideal portion 3e of the bed (cope) of concrete, keeping thickness s3 fixed, for the calculation on the basis of the homogenisation coefficient mi, in which 3e= (3d.mi) ;
- Allowable compression sigma 97.5 daN/cm2 - Allowable tau 6.0 daN/cm2
- Ec=18,000. sfRck 311,000 daN/cm2
- Volume mass 2,500 daN/cm2 Possible reinforcing fibres 4 inserted into concrete mixture not considered in the specific example. Their weight is negligible.
Lightening inserts (blocks) 5 without any structural importance. Their weight is negligible. Any pipe 6 of any kind inserted in positions which is not prejudicial to the static (case not considered in the specific example) .
Steel bars 7 FeB44k to be used only for supporting "negative" moments, i.e. moments at the bearings, which take place in a continuos structure as it is the case for a continuous floor on several spans as well as an overhanging floor (balcony or cantilever roof) .
The weight of any integration bar FeB44k is generally negligible.
- Allowable sigma 2,600 daN/cm2
- Allowable tau = sigma/ sβ 1,500 daN/cm2
- Modulus of elasticity E3 2,060,000 daN/cm2 Electrically welded mesh 8 with aggregation and distribution functions. It is not included in the calculation example and its weight is generally negligible.
For the homogenisation of the materials it is assumed: mi = (ERck3oo:EKVH select) = (311,000:100,000) = 3.11; in precautionary way it is assumed mi=2.5; m2 = (EFeB44k:EKvH select) = (1,060,000:100,000) = 20.60; in precautionary way it is assumed πi2=20.0;
SIZE OF THE COMPONENTS OF THE EXEMPLIFICATIVE FLOOR:
- total thickness s of the rustic floor 23 cm - thickness of the wood si KVH or other wood 6 cm
- thickness of the lightening insert s2
(for example of polystyrene) 12 cm
- thickness of concrete bed s3 (also indicated in the figure at 3c) 5 cm - total width b of the floor or a prefabricated floor panel centre distance bl between longitudinal concrete ribs (also indicated in the figures at 3a) provided in the gap between the lightening inserts 5. The centre distance between the longitudinal ribs has the same value of the corresponding strip of concrete bed at each longitudinal rib 77 cm centre distance between transversal curbs b2 of concrete (also indicated in the figures at 3b) in the gap between the lightening inserts 5 variable
- width of longitudinal rib b3 of unreinforced mass concrete except for the cases of negative moment 17 cm
- width of transversal curbs b4 of not necessarily reinforced mass concrete variable
- width of lightening inserts b5
(also indicated in the figures at 5) 60 cm - length of lightening inserts bβ, b7, b8, b9, respectively 40, 60, 80, 120 cm
- width of bed portion blO of concrete 3d
- width of ideal portion bll of concrete bed 3e
- inside span L between bearings - calculated span Lo; conventionally Lo= (L.1.05)
REFERENCES OF STATIC FUNCTIONALITY:
Jx,id = ideal moment of inertia incident to neutral axis
X-X defined on the basis of material homogenisation coefficients ; dx,inf = distance s4 of the lower floor surface from the neutral axis; dx,sup,cis = distance s5 of the upper floor surface from the neutral axis; dx,sup,Fe = distance s6 of the integration irons, added for the negative moments, from the neutral axis;
The test method provides that all materials are homogenised to wood. A band of wooden flooring and a strip of the concrete bed, both equal to the centre distance between longitudinal ribs, correspond to each longitudinal concrete rib. In praxis a double-T section having concrete core, bottom wooden flanges, and upper concrete flanges is formed. In the example, for the sake of simplicity and in favour of the safety, the longitudinal concrete curb between flooring 1 and the upper concrete bed 3 has been not considered in the calculation of Jx,id-
For the test of the moment in the span:
""x, lower, effective, wood. taut ™x,loweτ.ef£ = Jχ,id/dx, lower r
™x, upper, ideal, concrete. compressed ""X;Upper-id = 1Jx, id/ d-x, upper /
Wx, upper, effective, concrete, compressed ™x,up, eff=™x,up.eff=Wx,up.id/ ^ -3/ For testing the moment at bearings (structural continuity) :
Wx, lower, effective, wood. compressed ™x, lower . eff = Jx, id/ dx, lower r
™x, upper, ideal, iron . taut ™x, upper . id = Jχ, id/ dX / Upper ;
Wx, upper, effective, iron . taut Wx, Upper . eff = Wx, upp . id/ 2 0 ; Since a composite wood-cement section is taken into consideration, it is necessary to consider the shearing stress action in the two main directions, i.e. the transversal and the longitudinal shearing stresses (slipping) . For the test of the transversal shearing stress, the width of the longitudinal curb by the whole height of the wood + concrete, i.e. [b3.s], is taken into consideration. In fact, for a greater safety, the "flanges" of the "double-T" section are neglected. For the test of the slipping, the known formulas are used: Tmax = maximum shearing stress; Mi,x = static moment referred to the neutral axis; Mi,unixepox = static moment referred to the gluing plane; Jx,id = total ideal moment of inertia defined on the basis of the material homogenisation coefficients; Su = maximum unit slipping = Mi.Tmax/Jx,id;
According to the present invention, owing to the gluing of concrete 3 to wood 1 by the two-component, epoxy adhesive 2, the metal reinforcement for the transmission of the slipping forces between the concrete and wood portions is not necessary any longer because the slipping at the concrete-wood interface is totally compensated and transferred by the adhesive between the two materials. FLOOR ON TWO BEARINGS (figures 18-23) The invention provides that the floors on two bearings have in principle but not compulsorily longitudinal concrete ribs 3a without longitudinal metal reinforcement. Metal bars FeB44k are inserted at the bearings only in overhanging floors and continuous floors on two or more spans to compensate the tensile stress in the upper portion of the floor. Distance from the neutral axis of the lower surface of the floor (also indicate in the figures at s4) : dχ,iow=[ (167.5-5) (23-2, 5) + (77-6) "3] / (167.5 "5+77 -6) =14.3 cm;
Distance from the neutral axis of the upper surface of the floor (also indicate in the figures at s5) :
Figure imgf000022_0001
Ideal moment of inertia:
Figure imgf000022_0002
2.5) 2+ (77-6)- (14.3-3)2=94,317 cm4; Effective lower resistance module (wood KVH Select) : Wχ,iower= 94,317/14.3 = 6,595 cm3;
Ideal upper resistance module of concrete (Rck250) : Wχ,upper= 94,317/8.7 = 10,841 cm3;
Effective upper resistance module of concrete (Rck250) : (m=2.5)
Wχ,Upper.eff= 10,841/2.5 = 4,336 cm3; Attributable maximum bending moment:
- wood Mmax = 6,595.70 = 461,650 daN.cm;
- concrete Mmax = 4,336.97.5 = 422,760 daN.cm; = 4,227 daN.m;
Total maximum load, including dead load, on the strip of influence with a width of 77 cm: q = M.8 /Lo2, in which the calculation span λΛLo" is increased conventionally by 5% with respect to the span between the bearings; q = 4, 227-8/(6.00-1.05)2 = 852 daN/m;
= 1,106 daN/m2;
Dead weight of the floor: (wood+concrete, deducted the volume of polystyrene) : { (0.77 -0.06- 6.30) -600+[ (0.7710.18 "6.30 ) +
-0.60-0.12- (1.20+2- (0.80+0.60+0.40) ) ] "2500} /6.30=
= 237 daN/m = 308 daN/m2;
Allowable maximum operation load (permanent carried load + operation overload) : (852-237) = 615 daN/m = 799 daN/m2;
Determination of the elastic deformation for a total operation load of 500 daN/m2 (385 daN/m) . The maximum total load is 308 + 500 = 808 daN/m2 (622 daN/m) with a maximum total deformation of:
. 5 6,22 . 6304 f = . = 1.353 cm = Lo/465:
384 100,000 . 94,317 The following tests are made for 622 daN/m and 808 daN/m2 as a whole.
ACTION OF SHEARING STRESS
Shearing stress near the bearing in the position where there are still lightening inserts. To improve the safety and not considering the contribution of the flanges, an unreinforced rib with the minimum section of >» 17- (6+12+5)= 391 cm2 is installed
T = 622" (0.5-6.00-0.12) = 622"2,88 = 1,791 daN; Tautransversai = 1,791/391 = 4.58 daN/citi2 < 6 daN/cm2;
Shearing stress at the bearing over the lightening inserts where the solid wood-concrete section is >»
77*23 = 1,771 cm2;
Tautransversai = 622 '2.88/1, 771 = 1.01 daN/cm2 < 6 daN/cm2. 6 daN/cm2 is an allowable shearing stress for concrete
Rck 300, i.e. the lowest stress among the structural materials used in the example.
SLIPPING ACTION AT THE NEUTRAL AXIS
Resistance to slipping at the neutral axis X-X: Static moment Mi(lower) = 77 -6" (14.3-3) = 5,220 cm3;
Mi(upper) = 167.5-5- (8.7-2.5) = 5,192 cm3;
The slight difference is due to the previous rounding off. It is assumed Mi = 5,200 cm3.
Maximum unit slipping near the bearing (where the action of the lightening inserts is still present) >»
Sumax = Mi T/Jχ,id = 5,200-1,791/94,317 = 98.74 daN/cm;
At the minimum width of 17 cm >» Su = 98.74/17 = 5.8 daN/cm2 < 6 daN/cm2.
Over the position with the lightening inserts, the whole solid section is involved:
Sumax = (5,200-1,791/94,317) /77 = 1.28 daN/cm2 < 6 daN/cm2. SLIPPING ACTION IN THE WOOD-CONCRETE GLUING PLANE
(figures 22-23)
Still in case of a floor with two bearings, the slipping force at the concrete glued to wooden boards is strictly related to the thickness of such boards which determines the static moment with respect to the gluing plane.
The static moment of the flooring referred to the gluing plane is: M1 = (77-6) "3 = 1,386 cm3;
Over the lightening elements, where the section is solid, the maximum unit slipping force is >»
1,386-1,791/94,317 = 26.32 daN/cm;
Concrete is glued to wood at the longitudinal rib and also at the curbs formed at the transversal gap between the lightening elements. This allows the flooring to contribute to the statics all over its transversal width.
For a specific case the following slipping Su and the relative slipping stress are calculated for the different sectors of the flooring.
The following table relates to the drawings of sheet
11/13 where the areas (sectors) at which concrete is glued to wood are indicated. The quota of the slipping force Su and the unit stress on the basis of the surface available for gluing concrete to wood are indicate for each such sector.
Sector of Relative Available Unit stress at the
Flooring slipping surface glued interface force = Su for resin concrete to wood
D 550 daN 2,624 cm2 0.2K6 daN/cm2
C 1,101 daN 2,114 cm2 0.52<6 daN/cm2 B 1,223 daN 1,774 cm2 0.69<β daN/cm2 A 1,073 daN 3,112 cm2 0.34<β daN/cm2 It is self-evident from the table how much the gluing applied in length over the whole width of the flooring is important, especially at the transversal curbs of concrete formed at the gap between the lightening blocks. This is the inventive concept that causes the whole flooring to take active part to the statics all over its width. This is the first time that this technique is conceived and applied.
CONTINUOUS FLOOR ON THREE BEARINGS: TWO LIKE SPANS
(figs. 24-26)
622.6.302nn, . ^
Mmax central bearing = ~ = 3,086 daN.Hi; o
By inserting No. 3 bent irons 016 FeB44k (in the figures indicated at 7) and by homogenising iri2 = Ec/Es
= 20 and proceeding like above: s 4 = dx, lower = 6.4 cm; s6 = Sχ/Upper = 13.2 cm;
Ideal inertia = Jx,id = 28,422 cm4; Lower, effective compression strength modulus (wood
KVH Select) = Wx,lower = 28,422/6.4 = 4,441 cm3;
Sigma of wood=308, 600/4, 441 = 69.5 daN/cm2<85 daN/cm2;
Upper, ideal tensile strength modulus (FeB44k) =
= Wχ,upper = 28,422/13.2 = 2,153 cm3; Upper, effective tensile strength modulus (m2=20)=
= Wx,Upper.eff = 2,153/20 = 107.6 cm3;
S igmatensiie strength Fe = 308,600/107.6 = 2,868 daN/cm2, too high because > 2,600 daN/cm2;
By trying again with No. 2 016 + No. 1 020: dx,lower=6.9 cm; dx,Upper=12.8 cm; Jx,id=32, 459 cm4;
Figure imgf000027_0001
Sigma of wood = 65.6 daN/cm2;
SigmatensiiestrengthFe=308, 600/126=2, 449daN/cm2<2, 600daN/cm2. FLOOR ON TWO BEARINGS: ONE SPAN + OVERHANGING PART OF 1.70 METRES (figs. 27-29)
Greater overload on balcony >» +200 daN/m2=+154 daN/m M _ (622+154) .1.7O2 _Λ 1n1A ^τ
Mmax on the bearing with overhang ~ — ijl-ilClaJN.πi,
By inserting No. 3 bent irons 016 FeB44k (in the figures indicated at 7) and by homogenising iτi2 = Ec/Es = 20 and proceeding like above: s4 = dx,lower = 6.4 cm;
S6 = Sx,upper = 13.2 CItI;
Ideal inertia = Jx,id = 28,422 cm4;
Lower, effective compression strength modulus (wood KVH Select) = Wx,lower = 28,422/6.4 = 4,441 cm3;
Sigma of wood=112, 100/4, 441 = 25.2 daN/cm2<85 daN/cm2;
Upper, ideal tensile strength modulus (FeB44k)=
= Wx,upPer = 28,422/13.2 = 2,153 cm3;
Upper, effective tensile strength modulus (m2=20)= = Wx,upPer.eff = 2,153/20 = 107.6 cm3;
Sigmatensiie strength Fe = 112,100/107.6 = 1,042 daN/cm2 <
2,600 daN/cm2.
. (6.22+154).1704 . _._ ._., ΛT ... fmax = — = 0.285 cm = s/596. Very well! max 8.100,000.28,422
Any bar λλ10" of transversal aggregation between stiffening boards or frameworks λλll" just laid down inside the transversal curbs of concrete are not strictly necessary. Their possible application has no static motivation but only constructional aims. The present finding has been described and illustrated according to a preferred embodiment thereof, however, it is self-evident that anyone skilled in the art can make technically and/or functionally equivalent modifications and/or replacements without departing from the scope of the present industrial invention.

Claims

Claims
1. A method of manufacturing composite structural elements of wood (1) and concrete (3), characterized by the following steps:
- positioning the wooden component (1); - applying a structural adhesive (2) able to glue wood (1) and concrete (3) to each other;
- casting a green mixture of concrete (3) ;
- waiting for the maturation time of the casting (3) ;
- putting into operation of the composite structure thus obtained; said concrete (3) being cast in situ within the "open time" (pot life) of the structural adhesive 82), i.e. before the latter looses its adherence to wood (1) and concrete (3) .
2. The method according to claim 1, characterized in that said structural adhesive 82) is a two-component, epoxy adhesive able to make wood (1) and concrete (3) integral with each other and to prevent any slipping to each other, further providing a waterproof protection to wood (1).
3. The method according to claim 1, characterized in that said concrete (3) is of the fibre-reinforced type with a considerable omnidirectional tensile and shearing stress strengths, thus providing a valid reinforcing effect to the fibres belonging to the surfaces of wood interfaced to concrete and firmly connected to the latter because of the structural adhesive (2) .
4. The method according to claim 1, characterized in that the wooden part (1) consists of one or more solid and/or lamellar wood and/or KVH (Konstruktions VoIl HoIz) and/or single-layer or multilayer panels and/or reinforced wood both of the type with glued metal bar and glued fibres.
5. 'The method according to claim 1, characterized in that the wooden component (1) consists of several wooden elements placed side by side or crossed to one another for the production of beams and/or prefabricated floors of wood and concrete in the form of panels or plates or constructed directly in situ, suitable concrete casting (3) containment side walls (12) being provided.
6. The method according to claim 1, characterized in that the surface of wood (1) , on which the structural adhesive (2) is spread, is rough or provided with cuts, recesses, marks able to increase the effectiveness of the wood-concrete gluing and to improve the static strength.
7. The method according to claim 1, characterized in that relieves or stakes or lists of wood or other materials or still smooth or curved or perforated sheets are previously fastened to the surface of wood (1) in order to provide additional means of connection between wood (1) and concrete (3) .
8. The method according to claim 1, characterized in that the surface of wood 81) directed to the concrete casting 83) is provided with cuts (9) formed crosswise to the wood fibres, which cuts (9) are able to receive staffs or rods (10) of metal or other material which are secured by the adhesive (2) , said rods or staffs (10) being able to oppose the size variations of wood (1) in the transversal direction caused for example by swelling or shrinkage due to variations of the humidity content in the wood.
9. The method according to claim 8, characterized in that as an alternative or in addition to said transversal rods (10), small frameworks (11) with a reduced height to be completely "embedded" into the concrete casting (3) are used, said frameworks (11) having a further stiffening function.
10. The method according to claim 1, characterized in that structural adhesive (2) is applied to the wood by brush, spatula, roll, spray, casting or any other known method.
11. The method according to claim 1, characterized in that said structural adhesive (2) is enriched by metal fibres and/or glass fibres and/or carbon fibres and/or other reinforcement fibres.
12. The method according to claim 1, characterized in that said concrete (3) includes fluidising additives and/or superfluidising agents and/or retardant agents and/or accelerators and/or aeration agents and/or antifreeze and/or expanders and/or water-repellants, etc., said additives being compatible with the used structural adhesive (2).
13. The method according to claim 1, characterized in that lightening elements (5) of polystyrene and/or hollow elements of fired bricks and/or wood-cement and/or other known material are inserted into the thickness of the concrete casting (3) after having tested the statics of the building.
14. The method according to claim 1, characterized in that channels (6) for the passage of pipes are arranged in the thickness of concrete casting (3) after having tested the statics of the building.
15. The method according to claim 1, characterized in that meshes (8) of metal or other material having an anti-shrinkage and/or static function are inserted into the thickness of the concrete casting (3) .
16. The method according to claim 1, characterized in that integration frameworks and/or straight or curved reinforcement bars (7) are inserted into the thickness of the concrete casting (3) at the point of inversion of the bending moment, and/or integration bars for overhanging beams or floors are inserted into said thickness of the concrete casting.
17. The method according to claim 1, characterized in that in order to be applicable also 'to already existing wooden structures (1) , before the application of structural adhesive (2) and the concrete casting (3) there is provided:
- a preliminary thorough cleaning of the surfaces on which adhesive (2) should be spread; - the provisional support from the bottom and/or a suitable link from the top of the wooden elements (1); said support or link of the wooden structure being held in its position until concrete (3) achieves its carrying capability in combination with wooded elements (1) .
18. A method for the construction of any composite structural wood-concrete element as essentially described and illustrated in the present description and the accompanying drawings .
PCT/IT2006/000152 2005-03-14 2006-03-14 Process for manufacturing composite structural elements by gluing wood or its derivatives with concrete in the state of fresh mixture WO2006097962A1 (en)

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ITCO20050010 ITCO20050010A1 (en) 2005-03-14 2005-03-14 APPLICABLE PROCEDURE BETWEEN PRODUCTION IN THE FACTORY AND CONSTRUCTION OF COMPOSITE STRUCTURAL ELEMENTS OBTAINED FROM THE BONDED UNION OF WOOD OR ITS DERIVATIVES WITH CONCRETE IN THE FRESH MIXING STATE
ITCO2005A000010 2005-03-14

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Cited By (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2243891A1 (en) 2009-04-21 2010-10-27 Rodolphe Weibel Wood concrete composite slab
EP2787140A1 (en) * 2013-04-04 2014-10-08 Ed. Züblin AG Flat ceiling in composite wood concrete construction and method for producing such a ceiling
DE102016001185A1 (en) * 2016-02-03 2017-08-03 Lignotrend Gmbh & Co. Kg As a wood-concrete composite trained component and method for its preparation
AT518496A1 (en) * 2016-04-13 2017-10-15 Swa Systembauteile Gmbh Process for producing a composite element and composite element
US10260232B1 (en) 2017-12-02 2019-04-16 M-Fire Supression, Inc. Methods of designing and constructing Class-A fire-protected multi-story wood-framed buildings
US10290004B1 (en) 2017-12-02 2019-05-14 M-Fire Suppression, Inc. Supply chain management system for supplying clean fire inhibiting chemical (CFIC) totes to a network of wood-treating lumber and prefabrication panel factories and wood-framed building construction job sites
US10311444B1 (en) 2017-12-02 2019-06-04 M-Fire Suppression, Inc. Method of providing class-A fire-protection to wood-framed buildings using on-site spraying of clean fire inhibiting chemical liquid on exposed interior wood surfaces of the wood-framed buildings, and mobile computing systems for uploading fire-protection certifications and status information to a central database and remote access thereof by firefighters on job site locations during fire outbreaks on construction sites
US10332222B1 (en) 2017-12-02 2019-06-25 M-Fire Supression, Inc. Just-in-time factory methods, system and network for prefabricating class-A fire-protected wood-framed buildings and components used to construct the same
US10430757B2 (en) 2017-12-02 2019-10-01 N-Fire Suppression, Inc. Mass timber building factory system for producing prefabricated class-A fire-protected mass timber building components for use in constructing prefabricated class-A fire-protected mass timber buildings
WO2020051633A1 (en) * 2018-09-10 2020-03-19 Hcsl Pty Ltd Building panel
US11395931B2 (en) 2017-12-02 2022-07-26 Mighty Fire Breaker Llc Method of and system network for managing the application of fire and smoke inhibiting compositions on ground surfaces before the incidence of wild-fires, and also thereafter, upon smoldering ambers and ashes to reduce smoke and suppress fire re-ignition
US11400324B2 (en) 2017-12-02 2022-08-02 Mighty Fire Breaker Llc Method of protecting life, property, homes and businesses from wild fire by proactively applying environmentally-clean anti-fire (AF) chemical liquid spray in advance of wild fire arrival and managed using a wireless network with GPS-tracking
WO2023099306A1 (en) * 2021-11-30 2023-06-08 Sika Technology Ag Method for producing a laminate of wood and cementitious compositions
US11826592B2 (en) 2018-01-09 2023-11-28 Mighty Fire Breaker Llc Process of forming strategic chemical-type wildfire breaks on ground surfaces to proactively prevent fire ignition and flame spread, and reduce the production of smoke in the presence of a wild fire
US11865394B2 (en) 2017-12-03 2024-01-09 Mighty Fire Breaker Llc Environmentally-clean biodegradable water-based concentrates for producing fire inhibiting and fire extinguishing liquids for fighting class A and class B fires
US11865390B2 (en) 2017-12-03 2024-01-09 Mighty Fire Breaker Llc Environmentally-clean water-based fire inhibiting biochemical compositions, and methods of and apparatus for applying the same to protect property against wildfire
US11911643B2 (en) 2021-02-04 2024-02-27 Mighty Fire Breaker Llc Environmentally-clean fire inhibiting and extinguishing compositions and products for sorbing flammable liquids while inhibiting ignition and extinguishing fire

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE546445C (en) * 1932-03-12 Otto Schaub Wood-concrete composite body
US4841703A (en) * 1987-02-26 1989-06-27 Enterprise Paris Quest Floor with co-operation between wood and concrete
DE29511687U1 (en) * 1995-07-19 1995-09-28 Rinder Karl Dipl Ing Wooden beams - reinforced concrete beams - ceiling for renovation of old buildings
DE19729058A1 (en) * 1997-07-08 1999-01-14 Sika Ag Composite element and method for its production
DE10254043A1 (en) * 2002-11-20 2004-07-22 Universität Leipzig Composite construction of high load bearing capacity has profiled ribs are used as means of connection and are rigidly connected to wood or derived timber product and protrude into concrete

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE546445C (en) * 1932-03-12 Otto Schaub Wood-concrete composite body
US4841703A (en) * 1987-02-26 1989-06-27 Enterprise Paris Quest Floor with co-operation between wood and concrete
DE29511687U1 (en) * 1995-07-19 1995-09-28 Rinder Karl Dipl Ing Wooden beams - reinforced concrete beams - ceiling for renovation of old buildings
DE19729058A1 (en) * 1997-07-08 1999-01-14 Sika Ag Composite element and method for its production
DE10254043A1 (en) * 2002-11-20 2004-07-22 Universität Leipzig Composite construction of high load bearing capacity has profiled ribs are used as means of connection and are rigidly connected to wood or derived timber product and protrude into concrete

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EP2243891A1 (en) 2009-04-21 2010-10-27 Rodolphe Weibel Wood concrete composite slab
EP2787140A1 (en) * 2013-04-04 2014-10-08 Ed. Züblin AG Flat ceiling in composite wood concrete construction and method for producing such a ceiling
DE102016001185A1 (en) * 2016-02-03 2017-08-03 Lignotrend Gmbh & Co. Kg As a wood-concrete composite trained component and method for its preparation
AT518496B1 (en) * 2016-04-13 2021-12-15 Hans Ulrich Terkl Process for producing a composite element and composite element
AT518496A1 (en) * 2016-04-13 2017-10-15 Swa Systembauteile Gmbh Process for producing a composite element and composite element
US11633636B2 (en) 2017-12-02 2023-04-25 Mighty Fire Breaker Llc Wireless neighborhood wildfire defense system network supporting proactive protection of life and property in a neighborhood through GPS-tracking and mapping of environmentally-clean anti-fire (AF) chemical liquid spray applied to the property before wild fires reach the neighborhood
US11642555B2 (en) 2017-12-02 2023-05-09 Mighty Fire Breaker Llc Wireless wildfire defense system network for proactively defending homes and neighborhoods against wild fires by spraying environmentally-clean anti-fire chemical liquid on property and buildings and forming GPS-tracked and mapped chemical fire breaks about the property
US10311444B1 (en) 2017-12-02 2019-06-04 M-Fire Suppression, Inc. Method of providing class-A fire-protection to wood-framed buildings using on-site spraying of clean fire inhibiting chemical liquid on exposed interior wood surfaces of the wood-framed buildings, and mobile computing systems for uploading fire-protection certifications and status information to a central database and remote access thereof by firefighters on job site locations during fire outbreaks on construction sites
US10332222B1 (en) 2017-12-02 2019-06-25 M-Fire Supression, Inc. Just-in-time factory methods, system and network for prefabricating class-A fire-protected wood-framed buildings and components used to construct the same
US10430757B2 (en) 2017-12-02 2019-10-01 N-Fire Suppression, Inc. Mass timber building factory system for producing prefabricated class-A fire-protected mass timber building components for use in constructing prefabricated class-A fire-protected mass timber buildings
US11794044B2 (en) 2017-12-02 2023-10-24 Mighty Fire Breaker Llc Method of proactively forming and maintaining GPS-tracked and mapped environmentally-clean chemical firebreaks and fire protection zones that inhibit fire ignition and flame spread in the presence of wild fire
US10899038B2 (en) 2017-12-02 2021-01-26 M-Fire Holdings, Llc Class-A fire-protected wood products inhibiting ignition and spread of fire along class-A fire-protected wood surfaces and development of smoke from such fire
US10919178B2 (en) 2017-12-02 2021-02-16 M-Fire Holdings, Llc Class-A fire-protected oriented strand board (OSB) sheathing, and method of and automated factory for producing the same
US10267034B1 (en) 2017-12-02 2019-04-23 M-Fire Suppression, Inc. On-job-site method of and system for providing class-A fire-protection to wood-framed buildings during construction
US11395931B2 (en) 2017-12-02 2022-07-26 Mighty Fire Breaker Llc Method of and system network for managing the application of fire and smoke inhibiting compositions on ground surfaces before the incidence of wild-fires, and also thereafter, upon smoldering ambers and ashes to reduce smoke and suppress fire re-ignition
US11400324B2 (en) 2017-12-02 2022-08-02 Mighty Fire Breaker Llc Method of protecting life, property, homes and businesses from wild fire by proactively applying environmentally-clean anti-fire (AF) chemical liquid spray in advance of wild fire arrival and managed using a wireless network with GPS-tracking
US10260232B1 (en) 2017-12-02 2019-04-16 M-Fire Supression, Inc. Methods of designing and constructing Class-A fire-protected multi-story wood-framed buildings
US11638844B2 (en) 2017-12-02 2023-05-02 Mighty Fire Breaker Llc Method of proactively protecting property from wild fire by spraying environmentally-clean anti-fire chemical liquid on property surfaces prior to wild fire arrival using remote sensing and GPS-tracking and mapping enabled spraying
US10290004B1 (en) 2017-12-02 2019-05-14 M-Fire Suppression, Inc. Supply chain management system for supplying clean fire inhibiting chemical (CFIC) totes to a network of wood-treating lumber and prefabrication panel factories and wood-framed building construction job sites
US11654314B2 (en) 2017-12-02 2023-05-23 Mighty Fire Breaker Llc Method of managing the proactive spraying of environment ally-clean anti-fire chemical liquid on GPS-specified property surfaces so as to inhibit fire ignition and flame spread in the presence of wild fire
US11654313B2 (en) 2017-12-02 2023-05-23 Mighty Fire Breaker Llc Wireless communication network, GPS-tracked ground-based spraying tanker vehicles and command center configured for proactively spraying environmentally-safe anti-fire chemical liquid on property surfaces to inhibit fire ignition and flame spread in the presence of wild fire
US11730987B2 (en) 2017-12-02 2023-08-22 Mighty Fire Breaker Llc GPS tracking and mapping wildfire defense system network for proactively defending homes and neighborhoods against threat of wild fire by spraying environmentally-safe anti-fire chemical liquid on property surfaces to inhibit fire ignition and flame spread in the presence of wild fire
US11697041B2 (en) 2017-12-02 2023-07-11 Mighty Fire Breaker Llc Method of proactively defending combustible property against fire ignition and flame spread in the presence of wild fire
US11697039B2 (en) 2017-12-02 2023-07-11 Mighty Fire Breaker Llc Wireless communication network, GPS-tracked back-pack spraying systems and command center configured for proactively spraying environmentally-safe anti-fire chemical liquid on property surfaces to inhibit fire ignition and flame spread in the presence of wild fire
US11697040B2 (en) 2017-12-02 2023-07-11 Mighty Fire Breaker Llc Wild fire defense system network using a command center, spraying systems and mobile computing systems configured to proactively defend homes and neighborhoods against threat of wild fire by spraying environmentally-safe anti-fire chemical liquid on property surfaces before presence of wild fire
US11707639B2 (en) 2017-12-02 2023-07-25 Mighty Fire Breaker Llc Wireless communication network, GPS-tracked mobile spraying systems, and a command system configured for proactively spraying environmentally-safe anti-fire chemical liquid on combustible property surfaces to protect property against fire ignition and flame spread in the presence of wild fire
US11865394B2 (en) 2017-12-03 2024-01-09 Mighty Fire Breaker Llc Environmentally-clean biodegradable water-based concentrates for producing fire inhibiting and fire extinguishing liquids for fighting class A and class B fires
US11865390B2 (en) 2017-12-03 2024-01-09 Mighty Fire Breaker Llc Environmentally-clean water-based fire inhibiting biochemical compositions, and methods of and apparatus for applying the same to protect property against wildfire
US11826592B2 (en) 2018-01-09 2023-11-28 Mighty Fire Breaker Llc Process of forming strategic chemical-type wildfire breaks on ground surfaces to proactively prevent fire ignition and flame spread, and reduce the production of smoke in the presence of a wild fire
WO2020051633A1 (en) * 2018-09-10 2020-03-19 Hcsl Pty Ltd Building panel
US11911643B2 (en) 2021-02-04 2024-02-27 Mighty Fire Breaker Llc Environmentally-clean fire inhibiting and extinguishing compositions and products for sorbing flammable liquids while inhibiting ignition and extinguishing fire
WO2023099306A1 (en) * 2021-11-30 2023-06-08 Sika Technology Ag Method for producing a laminate of wood and cementitious compositions

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