EP1235964B9 - Method for the construction of a prestressed structure and prestressed structure thus obtained - Google Patents
Method for the construction of a prestressed structure and prestressed structure thus obtained Download PDFInfo
- Publication number
- EP1235964B9 EP1235964B9 EP99959683A EP99959683A EP1235964B9 EP 1235964 B9 EP1235964 B9 EP 1235964B9 EP 99959683 A EP99959683 A EP 99959683A EP 99959683 A EP99959683 A EP 99959683A EP 1235964 B9 EP1235964 B9 EP 1235964B9
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- European Patent Office
- Prior art keywords
- elements
- laminated timber
- glued laminated
- tendons
- timber beams
- Prior art date
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- E—FIXED CONSTRUCTIONS
- E04—BUILDING
- E04C—STRUCTURAL ELEMENTS; BUILDING MATERIALS
- E04C3/00—Structural elongated elements designed for load-supporting
- E04C3/02—Joists; Girders, trusses, or trusslike structures, e.g. prefabricated; Lintels; Transoms; Braces
- E04C3/12—Joists; Girders, trusses, or trusslike structures, e.g. prefabricated; Lintels; Transoms; Braces of wood, e.g. with reinforcements, with tensioning members
- E04C3/18—Joists; Girders, trusses, or trusslike structures, e.g. prefabricated; Lintels; Transoms; Braces of wood, e.g. with reinforcements, with tensioning members with metal or other reinforcements or tensioning members
- E04C3/185—Synthetic reinforcements
-
- E—FIXED CONSTRUCTIONS
- E04—BUILDING
- E04C—STRUCTURAL ELEMENTS; BUILDING MATERIALS
- E04C3/00—Structural elongated elements designed for load-supporting
- E04C3/02—Joists; Girders, trusses, or trusslike structures, e.g. prefabricated; Lintels; Transoms; Braces
- E04C3/12—Joists; Girders, trusses, or trusslike structures, e.g. prefabricated; Lintels; Transoms; Braces of wood, e.g. with reinforcements, with tensioning members
- E04C3/18—Joists; Girders, trusses, or trusslike structures, e.g. prefabricated; Lintels; Transoms; Braces of wood, e.g. with reinforcements, with tensioning members with metal or other reinforcements or tensioning members
Definitions
- the present invention relates to a method for the construction of a prestressed structure and to the prestressed structure thus obtained.
- various types of prestressed structures are known.
- Patent GB 1543069 A in which prestressed wooden construction elements are described having a set of prestressing strands, some of them fastened to the edges of the wooden support beam and the others having at least one end attached to an intermediate point of the support beam; a drawback concerning mainly one of the shown embodiments of the construction elements is that it is necessary to make ducts inside the support beam in order to position the strands; a drawback concerning another embodiment is that the tensioning operations of the strand are not easy, the strands being positioned on the two sides of the wooden support beam.
- Patent CH 284016 A in which a prestressed wooden beam is described comprising two wooden elements between which strands are positioned; a drawback concerning this embodiment is that the prestressed beam has a low lateral stability.
- the object of the present invention is that of providing prestressed structures which comprise glued laminated timber beams and tendons of the "external" type and which have considerable transverse stability.
- prestressed structure obtained in accordance with the method described above is characterized by the fact that it comprises in combination:
- the prestressed structure 1 which below is described when in use, is supported at its ends; more precisely, it is constrained with two external constraints 2, each of which is schematically represented as a hinge, and with two external constraints 3, each of which is schematically represented as a horizontally rolling support.
- the prestressed structure 1, which (during use) is subject to vertical concentrated loads 4 comprises in combination:
- the hydraulic jack which is positioned at the location of the terminal element 5b close to the external constraints 3, tensions, in accordance with a suitable tensioning sequence, the tendons 7, acting, by means of the said terminal element 5b (close to the external constraints 3), against the two glued laminated timber beams 5a; the ends of the tendons 7 close to the external constraints 2 have been previously anchored, by means of the associated wedges, to the terminal element 5b close to the said external constraints 2; during the tensioning operations each tendon 7 slides, except for its end close to the external constraints 2, with respect to the primary structure 5, substantially (the term “substantially” is used since frictional forces are present) free to slide along its whole length inside its sheath.
- FIGS 5 and 6 illustrate a prestressed structure 20 obtained according to the present invention, which is supported at its ends on two external constraints 21, each of which is schematically represented by a hinge, and on two external constraints 22, each of which is schematically represented by a horizontally rolling support.
- the prestressed structure 20, which is described below during use, is subject to vertical concentrated loads 23 and comprises in combination:
- connection elements may be made of glued laminated timber.
- the behaviour of the prestressed structure 20 and the method for the construction thereof are technically equivalent to those already described for the prestressed structure 1. It is pointed out that, during the first step of the method, the connection elements 24d are also made, which elements, during the second step of the method, are applied to the two glued laminated timber beams 24a.
- the method according to the present invention may sometimes comprise a fifth step, following the first four steps, during which relative displacements, permitted during the fourth step of the method, between the one or more tendons and the primary structure are permanently prevented; the abovementioned possible fifth step of the method is completed before the prestressed structure is put into service.
- the possible fifth step of the method may be useful for optimizing the behaviour in the "ultimate state" of the prestressed structure.
- some of the permanent loads or all the permanent loads may be applied to the said structure before the start of the fourth step of the method.
- each of the two or more glued laminated timber beams comprised in the primary structure may consist of the set of two (as in the case of each of the glued laminated timber beams 5a) or more glued laminated timber beams, with a rectangular cross-section, which are arranged in contact with one another and joined together so as to form a single beam.
- each of the two or more glued laminated timber beams included in the primary structure may have a straight axis or curved axis or axis formed as a broken line (with possible connecting radii).
- the two or more glued laminated timber beams may be of the solid-wall type or truss type or Vierendeel type or other types; in the case where the glued laminated timber beams are of the solid-wall type, each of them may have (for example) a rectangular cross-section or T-shaped cross-section or I-shaped cross-section with the upper flange the same as the lower flange or different from the lower flange.
- each of the two or more glued laminated timber beams may have a constant cross-section or a variable cross-section.
- each of the two or more glued laminated timber beams may comprise two or more segments joined together and located, in the longitudinal direction, one after another; these segments are assembled on-site before implementing the third step of the method; it is pointed out that, generally, the stress states at the location of the joints between the abovementioned segments may be improved as a result of the prestressing. It is possible to have a prestressed structure obtained according to the present invention (this embodiment is not illustrated in the figures) in which each tendon is entirely positioned between the glued laminated timber beams (i.e. is entirely positioned in the space between the glued laminated timber beams).
- each of the abovementioned groups of strands is contained in a tubular housing element which is made of synthetic material and inside which a filling material has also been introduced; it is pointed out that each strand may be greased and contained inside its own sheath made of synthetic material such that sliding of each strand inside its sheath is permitted. It is possible to have a prestressed structure obtained according to the present invention in which a single deviating element is present.
- a prestressed structure obtained according to the present invention in which more than two glued laminated timber beams are present; these glued laminated timber beams are spaced from one another and are connected together by means of the terminal elements and of the one or more deviating elements; it is pointed out that connection elements applied to the abovementioned glued laminated timber beams may also be present.
- the tendons consist, for example, of strands or bars or wires; it is pointed out that the tendons may be made of steel or may be made using synthetic materials or composite materials or also other suitable materials.
- the primary structure also comprises retaining elements which connect the primary structure and the tendons at points where the path followed by the tendons does not change direction.
- the present invention it is possible to produce, in addition to prestressed structures externally constrained in an isostatic manner, also prestressed structure externally constrained in a hyperstatic manner.
- An advantage of the present invention consists in the fact that, using a prestressed structure obtained according to the present invention instead of an "equivalent" traditional glued laminated timber beam, it is possible to reduce the quantity of glued laminated timber to be used.
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- Engineering & Computer Science (AREA)
- Architecture (AREA)
- Life Sciences & Earth Sciences (AREA)
- Wood Science & Technology (AREA)
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- Structural Engineering (AREA)
- Rod-Shaped Construction Members (AREA)
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Abstract
Description
- The present invention relates to a method for the construction of a prestressed structure and to the prestressed structure thus obtained. In the art various types of prestressed structures are known.
- It is known the Patent
GB 1543069 A - It is also known the Patent
CH 284016 A - In a prestressed beam, as it is known, steel reinforcements are used, said reinforcements, suitably tensioned, inducing in the said beam a compressive normal force, bending moments and, in some cases, shear forces. Beams made of prestressed concrete are very widespread.
- The object of the present invention is that of providing prestressed structures which comprise glued laminated timber beams and tendons of the "external" type and which have considerable transverse stability. These and other objects are achieved by the method for the construction of a prestressed structure according to the present invention and by the prestressed structure thus obtained, also according to the present invention.
- The abovementioned method for the construction of a prestressed structure is characterized by the fact that it comprises the following steps:
- first step: two or more glued laminated timber beams, two terminal elements, one or more deviating elements and one or more tendons are made;
each of said terminal elements consists of a set of metal elements which comprises two or more end-pieces and one or more cross-pieces which are joined to said two or more end-pieces; each of said end-pieces is to be in contact with one end of one of said two or more glued laminated timber beams; each of said one or more deviating elements consists of a set of metal elements which comprises elements to be placed in contact with said glued laminated timber beams and suitably shaped elements which are to be placed in contact with said tendons;
said glued laminated timber
beams, said terminal elements, said one or more deviating elements and said one or more tendons, from the start, are designed and made so as to produce the prestressed structure; - second step: a primary structure is assembled, applying said terminal elements and said one or more deviating elements to said glued laminated timber beams; said terminal elements are applied to the ends of said glued laminated timber beams; at the end of said second step of the method, said glued laminated timber beams are spaced from one another and are connected together by means of said terminal elements and of said one or more deviating elements;
- third step: said one or more tendons are arranged in position, in contact with said one or more deviating elements and with said terminal elements; at the location of said one or more deviating elements, the path followed by said one or more tendons changes direction; each of said one or more tendons is located outside the cross-section of said glued laminated timber beams and is positioned, at least partly, between said glued laminated timber beams;
- fourth step: tensioning of said one or more tendons is performed, said tendons being then anchored, at their ends, to said terminal elements; said tensioning is performed using means which act against said glued laminated timber beams through the terminal element with which said means are in contact; each of said one or more tendons, during said tensioning, being subject to a tensile normal force, lengthens, sliding longitudinally with respect to said primary structure; following said tensioning, said one or more tendons, at the location of said terminal elements and of said one or more deviating elements, apply to said primary structure a system of forces which produces bending in said primary structure, inducing in said primary structure a compressive normal force; said fourth step of the method is completed before the prestressed structure is put into service.
- The prestressed structure obtained in accordance with the method described above (prestressed structure which also forms the subject of the present invention) is characterized by the fact that it comprises in combination:
- a primary structure comprising two or more glued laminated timber beams, two terminal elements applied to the ends of said glued laminated timber beams and one or more deviating elements applied to said glued laminated timber beams; said glued laminated timber beams are spaced from one another and are connected together by means of said terminal elements and of said one or more deviating elements;
- one or more tendons, each of which has its ends anchored to said terminal elements and is in contact with said one or more deviating elements;
each of said terminal elements consists of a set of metal elements which comprises two or more end-pieces and one or more cross-pieces which are joined to said two or more end-pieces; each of said end-pieces is in contact with one end of one of said two or more glued laminated timber beams; each of said one or more deviating elements consists of a set of metal elements which comprises elements placed in contact with said glued laminated timber beams and suitably shaped elements which are placed in contact with said tendons;
at the location of said one or more deviating elements the path followed by said one or more tendons changes direction; each of said one or more tendons is located outside the cross-section of said glued laminated timber beams and is positioned, at least partly, between said glued laminated timber beams; said one or more tendons, at the location of said terminal elements and of said one or more deviating elements, apply to said primary structure forces which produce bending in said primary structure, inducing in said primary structure a compressive normal force; said forces are due to the tensioning of said one or more tendons, performed during the construction of the prestressed structure, and to the loads applied to said prestressed structure; in particular, as a result of said tensioning, said one or more tendons, at the location of said terminal elements and of said one or more deviating elements, apply to said primary structure a system of forces which produces bending in said primary structure, inducing in said primary structure a compressive normal force. - The characteristic features and advantages of the present invention will emerge more clearly from the following description of two embodiments illustrated purely by way of a non-limiting example in the accompanying plates of drawings, in which:
-
Figure 1 shows a partly longitudinal view and partly longitudinally sectioned view of a prestressed structure obtained according to the present invention; -
Figure 2 shows, on a scale larger than that ofFigure 1 , the cross-section along the line I-I ofFigure 1 ; -
Figure 3 shows, on the same scale asfigure 2 , a detail ofFigure 1 ; -
Figure 4 shows, on the same scale asFigure 2 , the view, from one of the two ends, of the prestressed structure according toFigure 1 ; -
Figure 5 shows a partly longitudinal view and partly longitudinally sectioned view of a prestressed structure obtained in accordance with the present invention, according to a further embodiment; -
Figure 6 shows, on a larger scale than that ofFigure 5 , the cross-section along the line II-II ofFigure 5 . - For the sake of simplicity of the illustration, welding, bolting, nailing or other joining systems have not been shown in the abovementioned figures.
- Below, in order to facilitate the understanding of the steps of the method according to the present invention, first of all, with reference to
Figures 1, 2, 3 and 4 , a prestressed structure 1 obtained according to the present invention is described. The prestressed structure 1, which below is described when in use, is supported at its ends; more precisely, it is constrained with two external constraints 2, each of which is schematically represented as a hinge, and with twoexternal constraints 3, each of which is schematically represented as a horizontally rolling support. The prestressed structure 1, which (during use) is subject to vertical concentrated loads 4, comprises in combination: - a
primary structure 5 comprising two glued laminated timber beams (glulam beams) 5a, twoterminal elements 5b applied to the ends of the two glued laminatedtimber beams 5a and five deviatingelements timber beams 5a; the glued laminatedtimber beams 5a are spaced from each other and are connected together by means of theterminal elements 5b and of the deviatingelements timber beams 5a, which have a straight and horizontal axis, have a rectangular cross-section; the glued laminatedtimber beams 5a are identical and parallel to each other; each of the two glued laminatedtimber beams 5a consists of the set of two glued laminated timber beams 6 which are identical to each other and have a rectangular cross-section and which are placed in contact with each other and joined together; - eight
tendons 7, each of which has its ends anchored to the twoterminal elements 5b and is in contact with the five deviatingelements elements tendons 7 changes direction; eachtendon 7 is located outside the cross-section of the two glued laminatedtimber beams 5a and is positioned, partly (i.e. along the portions close to its ends), between the said two glued laminatedtimber beams 5a; it is pointed out that the expression "positioned partly between the two glued laminatedtimber beams 5a" is understood as meaning "positioned partly in the space between the two glued laminatedtimber beams 5a"; thetendons 7, at the location of theterminal elements 5b and of the deviatingelements primary structure 5 forces which produce bending in theprimary structure 5, inducing in the saidprimary structure 5 a compressive normal force; the abovementioned forces are due to the tensioning of thetendons 7, performed during the construction of the prestressed structure 1, and to the loads 4 which are applied, during use, to the prestressed structure 1 itself; in particular, as a result of the abovementioned tensioning, thetendons 7, at the location of theterminal elements 5b and of the deviatingelements primary structure 5 a system of forces which produces (upwards) bending in theprimary structure 5, inducing in the saidprimary structure 5 a compressive normal force. It is pointed out that the intensity of the forces applied by thetendons 7 to theprimary structure 5 is influenced by the decrease in tension due (among other things) to the relaxation of the steel and to the long-term deformations (creep) of the glued laminated timber. Eachtendon 7 consists of a high-strength steel strand (steel, that is, having for example a tensile strength greater than 1750 N/mm2) contained in its own sheath of synthetic material inside which the strand itself is able to slide. Each of the twoterminal elements 5b consists of a set of metal elements which comprises two end-pieces 8, each of which is in contact with one of the two glued laminatedtimber beams 5a, twocross-pieces pieces 8 and ananchoring element 10 which is joined to thecross-piece 9a; thetendons 7 are anchored at the location of theanchoring elements 10 by means of wedges. It is pointed out that, according to a variation, not shown in the figures, with reference to each of the two terminal elements, the end-pieces, as well as the end cross-sections of the glued laminated timber beams, are substantially perpendicular not to the axes of the said glued laminated timber beams, but to the axes of the tendons which are anchored at the location of the terminal element itself. It is pointed out that, according to another embodiment, not shown in the figures, the end-pieces may have dimensions which are smaller than the height of the cross-section of the glued laminated timber beams. Each of the five deviatingelements timber beams 5a and suitably shaped elements which, placed in contact with thetendons 7, deviate the path of the saidtendons 7. It is pointed out that, in the prestressed structure 1, the axes of the deviatingelements timber beams 5a; according to a variation, not shown in the figures, the axis of each deviating element is directed along the bisector of the angle formed between the two sections of each tendon located respectively on either side of the said deviating element. - The method, according to the present invention, for the construction of the prestressed structure 1 is described below, said method comprising the following steps:
- first step: the two glued laminated
timber beams 5a, the twoterminal elements 5b, the five deviatingelements tendons 7 are made; the two glued laminatedtimber beams 5a, theterminal elements 5b, the deviatingelements tendons 7, from the start, are designed and made so as to produce the prestressed structure 1; - second step: the
primary structure 5 is assembled on-site, applying theterminal elements 5b and the deviatingelements timber beams 5a; theterminal elements 5b are applied to the ends of the glued laminatedtimber beams 5a; at the end of the second step of the method, the two glued laminatedtimber beams 5a are spaced from each other and are connected together by means of theterminal elements 5b and of the deviatingelements - third step: the
tendons 7 are arranged in position, in contact with the deviatingelements terminal elements 5b; at the location of the deviatingelements tendons 7 changes direction; eachtendon 7 is located outside the cross-section of the two glued laminatedtimber beams 5a and is positioned, partly, between the said two glued laminatedtimber beams 5a; it is pointed out that thetendons 7 are inserted inside the deviatingelements primary structure 5, with thetendons 7 already arranged in position (as described above), is installed, positioning it on the external constraints 2 and theexternal constraints 3; - fourth step: tensioning of the
tendons 7 is performed, said tendons being then anchored, at their ends, to theterminal elements 5b; the abovementioned tensioning is performed using a hydraulic jack (not shown in the figures) which acts against the two glued laminatedtimber beams 5a through theterminal element 5b with which said hydraulic jack is in contact; eachtendon 7, during the abovementioned tensioning operation, being subject to a tensile normal force, lengthens, sliding longitudinally with respect to theprimary structure 5; following the abovementioned tensioning, thetendons 7, at the location of theterminal elements 5b and of the deviatingelements primary structure 5 a system of forces which produces bending in theprimary structure 5, inducing in the saidprimary structure 5 a compressive normal force; the fourth step of the method is completed before the prestressed structure 1 is put into service. - With respect to the fourth step of the method the following is pointed out: the hydraulic jack, mentioned above, which is positioned at the location of the
terminal element 5b close to theexternal constraints 3, tensions, in accordance with a suitable tensioning sequence, thetendons 7, acting, by means of the saidterminal element 5b (close to the external constraints 3), against the two glued laminatedtimber beams 5a; the ends of thetendons 7 close to the external constraints 2 have been previously anchored, by means of the associated wedges, to theterminal element 5b close to the said external constraints 2; during the tensioning operations eachtendon 7 slides, except for its end close to the external constraints 2, with respect to theprimary structure 5, substantially (the term "substantially" is used since frictional forces are present) free to slide along its whole length inside its sheath. Then, after thetendons 7 have been anchored by means of the associated wedges to theterminal element 5b close to theexternal constraints 3, in order to obtain (as far as possible) a symmetrical distribution of the stresses, by means of the abovementioned jack, which is now positioned at the location of theterminal element 5b close to the external constraints 2, the operations of tensioning of the saidtendons 7 are completed. The hydraulic jack is then deactivated and definitively removed. The result is that, at the end of the fourth step of the method, the ends of thetendons 7 are definitively anchored to theterminal elements 5b. The fourth step of the method terminates with the completion of the operations described above. The method for the construction of the prestressed structure 1 is concluded with termination of the fourth step. Then, once the method has been terminated, the prestressed structure 1 is put into service and the loads 4 are applied to it. -
Figures 5 and 6 illustrate aprestressed structure 20 obtained according to the present invention, which is supported at its ends on twoexternal constraints 21, each of which is schematically represented by a hinge, and on twoexternal constraints 22, each of which is schematically represented by a horizontally rolling support. Theprestressed structure 20, which is described below during use, is subject to vertical concentratedloads 23 and comprises in combination: - a
primary structure 24 comprising two glued laminatedtimber beams 24a with a rectangular cross-section, twometal terminal elements 24b which are applied to the ends of the two glued laminatedtimber beams 24a, twometal deviating elements 24c applied to the two glued laminatedtimber beams 24a, andmetal connection elements 24d applied to the two glued laminatedtimber beams 24a; the two glued laminatedtimber beams 24a are spaced from each other and are connected together by means of theterminal elements 24b, of the deviatingelements 24c and of theconnection elements 24d; the two glued laminatedtimber beams 24a have a straight and horizontal axis; - six
tendons 25, each of which has its ends anchored to theterminal elements 24b and is in contact with the deviatingelements 24c; eachtendon 25 consists of a high-strength steel strand contained inside a sheath of synthetic material inside which the strand itself is able to slide. - It is pointed out that, for the sake of simplicity of the illustration, structural steel elements, which are arranged in an X shape and located in the horizontal plane which contains the axes of the
connection elements 24d, have not been shown inFigures 5 and 6 : the abovementioned structural elements arranged in an X shape complete the formation of a bracing structural system situated in the plane in which said elements lie. According to another embodiment, not shown in the figures, the connection elements (mentioned above) may be made of glued laminated timber. The behaviour of theprestressed structure 20 and the method for the construction thereof are technically equivalent to those already described for the prestressed structure 1. It is pointed out that, during the first step of the method, theconnection elements 24d are also made, which elements, during the second step of the method, are applied to the two glued laminatedtimber beams 24a. - In general, the method according to the present invention may sometimes comprise a fifth step, following the first four steps, during which relative displacements, permitted during the fourth step of the method, between the one or more tendons and the primary structure are permanently prevented; the abovementioned possible fifth step of the method is completed before the prestressed structure is put into service. In general the possible fifth step of the method may be useful for optimizing the behaviour in the "ultimate state" of the prestressed structure. With reference to the method according to the present invention for the construction of a prestressed structure, generally, some of the permanent loads or all the permanent loads may be applied to the said structure before the start of the fourth step of the method.
- In a prestressed structure obtained according to the present invention each of the two or more glued laminated timber beams comprised in the primary structure may consist of the set of two (as in the case of each of the glued laminated
timber beams 5a) or more glued laminated timber beams, with a rectangular cross-section, which are arranged in contact with one another and joined together so as to form a single beam. In a prestressed structure obtained according to the present invention each of the two or more glued laminated timber beams included in the primary structure may have a straight axis or curved axis or axis formed as a broken line (with possible connecting radii). In a prestressed structure obtained according to the present invention the two or more glued laminated timber beams (included in the primary structure) may be of the solid-wall type or truss type or Vierendeel type or other types; in the case where the glued laminated timber beams are of the solid-wall type, each of them may have (for example) a rectangular cross-section or T-shaped cross-section or I-shaped cross-section with the upper flange the same as the lower flange or different from the lower flange. In a prestressed structure obtained according to the present invention each of the two or more glued laminated timber beams (included in the primary structure) may have a constant cross-section or a variable cross-section. In a prestressed structure obtained according to the present invention each of the two or more glued laminated timber beams (included in the primary structure) may comprise two or more segments joined together and located, in the longitudinal direction, one after another; these segments are assembled on-site before implementing the third step of the method; it is pointed out that, generally, the stress states at the location of the joints between the abovementioned segments may be improved as a result of the prestressing. It is possible to have a prestressed structure obtained according to the present invention (this embodiment is not illustrated in the figures) in which each tendon is entirely positioned between the glued laminated timber beams (i.e. is entirely positioned in the space between the glued laminated timber beams). It is therefore possible to have a prestressed structure obtained according to the present invention in which only one tendon is present. It is possible to have a prestressed structure obtained according to the present invention in which the tendons consist of high-strength steel strands grouped together in one or more groups of strands; each of the abovementioned groups of strands is contained in a tubular housing element which is made of synthetic material and inside which a filling material has also been introduced; it is pointed out that each strand may be greased and contained inside its own sheath made of synthetic material such that sliding of each strand inside its sheath is permitted. It is possible to have a prestressed structure obtained according to the present invention in which a single deviating element is present. It is possible to have a prestressed structure obtained according to the present invention in which more than two glued laminated timber beams are present; these glued laminated timber beams are spaced from one another and are connected together by means of the terminal elements and of the one or more deviating elements; it is pointed out that connection elements applied to the abovementioned glued laminated timber beams may also be present. In a prestressed structure obtained according to the present invention the tendons consist, for example, of strands or bars or wires; it is pointed out that the tendons may be made of steel or may be made using synthetic materials or composite materials or also other suitable materials. - It is possible to have a prestressed structure obtained according to the present invention (not shown in the figures) in which the primary structure also comprises retaining elements which connect the primary structure and the tendons at points where the path followed by the tendons does not change direction. According to the present invention it is possible to produce, in addition to prestressed structures externally constrained in an isostatic manner, also prestressed structure externally constrained in a hyperstatic manner. An advantage of the present invention consists in the fact that, using a prestressed structure obtained according to the present invention instead of an "equivalent" traditional glued laminated timber beam, it is possible to reduce the quantity of glued laminated timber to be used.
Claims (10)
- Method for the construction of a prestressed structure, characterized in that it comprises the following steps:- first step: two or more glued laminated timber beams (5a, 24a), two terminal elements (5b, 24b), one or more deviating elements (5c, 5d, 5e, 24c) and one or more tendons (7, 25) are made;
each of said terminal elements consists of a set of metal elements which comprises two or more end-pieces (8) and one or more cross-pieces (9a, 9b) which are joined to said two or more end-pieces; each of said end-pieces is to be in contact with one end of one of the two or more glued laminated timber beams (5a, 24a); each of said one or more deviating elements consists of a set of metal elements which comprises elements to be placed in contact with the glued laminated timber beams (5a, 24a) and suitably shaped elements which are to be placed in contact with the tendons (7,25);
the glued laminated timber beams (5a, 24a), the terminal elements (5b, 24b), the one or more deviating elements (5c, 5d, 5e, 24c) and the one or more tendons (7, 25), from the start, are designed and made so as to produce the prestressed structure (1, 20);- second step: a primary structure (5, 24) is assembled, applying the terminal elements (5b, 24b) and the one or more deviating elements (5c, 5d, 5e, 24c) to the glued laminated timber beams (5a, 24a); the terminal elements (5b, 24b) are applied to the ends of the glued laminated timber beams (5a, 24a); at the end of said second step of the method, the glued laminated timber beams (5a, 24a) are spaced from one another and are connected together by means of the terminal elements (5b, 24b) and of the one or more deviating elements (5c, 5d, 5e, 24c);- third step: the one or more tendons (7, 25) are arranged in position, in contact with the one or more deviating elements (5c, 5d, 5e, 24c) and with the terminal elements (5b, 24b); at the location of the one or more deviating elements (5c, 5d, 5e, 24c) the path followed by the one or more tendons (7, 25) changes direction; each of the one or more tendons (7, 25) is located outside the cross-section of the glued laminated timber beams (5a, 24a) and is positioned, at least partly, between said glued laminated timber beams;- fourth step: tensioning of the one or more tendons (7, 25) is performed, said tendons being then anchored, at their ends, to the terminal elements (5b, 24b); said tensioning is performed using means which act against the glued laminated timber beams (5a, 24a) through the terminal element (5b, 24b) with which said means are in contact; each of the one or more tendons (7, 25), during said tensioning, being subject to a tensile normal force, lengthens, sliding longitudinally with respect to the primary structure (5, 24); following said tensioning, the one or more tendons (7, 25), at the location of the terminal elements (5b, 24b) and of the one or more deviating elements (5c, 5d, 5e, 24c), apply to the primary structure (5, 24) a system of forces which produces bending in said primary structure, inducing in said primary structure a compressive normal force; said fourth step of the method is completed before the prestressed structure (1, 20) is put into service. - Method according to Claim 1, characterized in that it comprises a fifth step, following the first four steps, during which relative displacements, permitted during the fourth step of the method, between one or more tendons and the primary structure are permanently prevented; said fifth step of the method is completed before the prestressed structure is put into service.
- Method according to Claim 1, characterized in that, during the first step of said method, connection elements (24d) are made, which elements, during the second step of said method, are applied to the two or more glued laminated timber beams (24a).
- Prestressed structure obtained according to the method according to Claim 1, characterized in that it comprises in combination:- a primary structure (5, 24) comprising two or more glued laminated timber beams (5a, 24a), two terminal elements (5b, 24b) applied to the ends of said glued laminated timber beams and one or more deviating elements (5c, 5d, 5e, 24c) applied to said glued laminated timber beams; the glued laminated timber beams (5a, 24a) are spaced from one another and are connected together by means of the terminal elements (5b, 24b) and of the one or more deviating elements (5c, 5d, 5e, 24c);- one or more tendons (7, 25), each of which has its ends anchored to the terminal elements (5b, 24b) and is in contact with the one or more deviating elements (5c, 5d, 5e, 24c);
each of said terminal elements consists of a set of metal elements which comprises two or more end-pieces (8) and one or more cross-pieces (9a, 9b) which are joined to said two or more end-pieces; each of said end-pieces is in contact with one end of one of the two or more glued laminated timber beams (5a, 24a); each of said one or more deviating elements consists of a set of metal elements which comprises elements placed in contact with the glued laminated timber beams (5a, 24a) and suitably shaped elements which are placed in contact with the tendons (7, 25);
at the location of the one or more deviating elements (5c, 5d, 5e, 24c) the path followed by the one or more tendons (7, 25) changes direction; each of the one or more tendons (7, 25) is located outside the cross-section of the glued laminated timber beams (5a, 24a) and is positioned, at least partly, between said glued laminated timber beams; the one or more tendons (7, 25), at the location of the terminal elements (5b, 24b) and of the one or more deviating elements (5c, 5d, 5e, 24c), apply to the primary structure (5, 24) forces which produce bending in said primary structure, inducing in said primary structure a compressive normal force; said forces are due to the tensioning of the one or more tendons (7, 25), performed during the construction of the prestressed structure (1, 20), and to the loads (4, 23) applied to said prestressed structure; in particular, as a result of said tensioning, the one or more tendons (7, 25), at the location of the terminal elements (5b, 24b) and of the one or more deviating elements (5c, 5d, 5e, 24c), apply to the primary structure (5, 24) a system of forces which produces bending in said primary structure, inducing in said primary structure a compressive normal force. - Prestressed structure according to Claim 4, characterized in that the primary structure (24) comprises connection elements (24d) applied to the two or more glued laminated timber beams (24a); the glued laminated timber beams (24a) are spaced from one another and are connected together also by means of the connection elements (24d).
- Prestressed structure according to Claim 4, characterized in that each of the two or more glued laminated timber beams (5a) consists of the set of two or more glued laminated timber beams (6), with a rectangular cross-section, which are arranged in contact with one another and joined together so as to form a single beam.
- Prestressed structure according to Claim 4, characterized in that the two or more glued laminated timber beams (5a, 24a) have a straight axis and have a rectangular cross-section.
- Prestressed structure according to Claim 4, characterized in that each of the two or more glued laminated timber beams has a curved axis or axis formed as a broken line.
- Prestressed structure according to Claim 4, characterized in that each of the two or more glued laminated timber beams has a T-shaped cross-section or I-shaped cross-section with the upper flange the same as the lower flange or different from the lower flange.
- Prestressed structure according to Claim 4, characterized in that each of the two or more glued laminated timber beams comprises two or more segments joined together and located, in the longitudinal direction, one after another.
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
PCT/IT1999/000404 WO2001042584A1 (en) | 1999-12-07 | 1999-12-07 | Method for the construction of a prestressed structure and prestressed structure thus obtained |
Publications (3)
Publication Number | Publication Date |
---|---|
EP1235964A1 EP1235964A1 (en) | 2002-09-04 |
EP1235964B1 EP1235964B1 (en) | 2008-09-10 |
EP1235964B9 true EP1235964B9 (en) | 2009-03-25 |
Family
ID=11333135
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP99959683A Expired - Lifetime EP1235964B9 (en) | 1999-12-07 | 1999-12-07 | Method for the construction of a prestressed structure and prestressed structure thus obtained |
Country Status (4)
Country | Link |
---|---|
EP (1) | EP1235964B9 (en) |
AT (1) | ATE408045T1 (en) |
DE (1) | DE69939557D1 (en) |
WO (1) | WO2001042584A1 (en) |
Families Citing this family (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2006007659A1 (en) * | 2004-07-21 | 2006-01-26 | S2 Holdings Pty Limited | Building methods |
WO2006007660A1 (en) * | 2004-07-21 | 2006-01-26 | Murray Ellen | Building methods |
FR2947593A1 (en) * | 2009-07-01 | 2011-01-07 | Univ Nancy 1 Henri Poincare | METHOD FOR MANUFACTURING FIBROUS MATERIAL ASSEMBLIES FOR CARRYING OUT A SUPPORT STRUCTURE, ASSEMBLIES OBTAINED THEREBY, AND STRUCTURE USING SAID ASSEMBLIES |
CN104032891A (en) * | 2014-05-27 | 2014-09-10 | 南京工业大学 | Prestressed double laminated wood beam |
CN104533014B (en) * | 2014-12-24 | 2016-05-25 | 南京工业大学 | A kind of built-in prestressed timber beam |
CN104675017B (en) * | 2015-03-06 | 2016-07-27 | 东北林业大学 | A kind of novel Prestressed Continuous bamboo wooden frame promotes device |
CN106958315A (en) * | 2017-05-17 | 2017-07-18 | 东北林业大学 | A kind of double limb controllable prestressing force beam string structures of large span |
CN107268891B (en) * | 2017-06-26 | 2023-04-07 | 东北林业大学 | Adjustable prestressed laminated wood beam string continuous beam |
Family Cites Families (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE859522C (en) * | 1948-10-02 | 1952-12-15 | Theodor Hahn | Wooden beam reinforced with tie rods |
CH284016A (en) * | 1950-08-22 | 1952-07-15 | Emil Dr Staudacher | Construction element made of wood. |
FI53155C (en) * | 1975-06-24 | 1979-09-17 | Vierumaeen Teollisuus Oy | FOERSPAENT BYGGNADSELEMENT MED EN TRAEKONSTRUKTION |
US4450662A (en) * | 1982-06-01 | 1984-05-29 | Melchiori Jr Remo | Tensioned structure with adjustably movable columns and beams |
JP3027931B2 (en) * | 1996-02-16 | 2000-04-04 | ピーシー橋梁株式会社 | Prestressed laminated timber beam and method of manufacturing the same |
-
1999
- 1999-12-07 WO PCT/IT1999/000404 patent/WO2001042584A1/en active IP Right Grant
- 1999-12-07 AT AT99959683T patent/ATE408045T1/en active
- 1999-12-07 DE DE69939557T patent/DE69939557D1/en not_active Expired - Lifetime
- 1999-12-07 EP EP99959683A patent/EP1235964B9/en not_active Expired - Lifetime
Also Published As
Publication number | Publication date |
---|---|
DE69939557D1 (en) | 2008-10-23 |
EP1235964B1 (en) | 2008-09-10 |
WO2001042584A1 (en) | 2001-06-14 |
ATE408045T1 (en) | 2008-09-15 |
EP1235964A1 (en) | 2002-09-04 |
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