초록 ▼

A method whereby the strands (13,13A) are fixed one after another between two cable anchors (A,B) integral with the structure. The method consists: in pulling on one of the ends of a strand (13A) from one (A) of the cable anchors, while the other end is fixed on the other cable anchor (B); continuou

A method whereby the strands (13,13A) are fixed one after another between two cable anchors (A,B) integral with the structure. The method consists: in pulling on one of the ends of a strand (13A) from one (A) of the cable anchors, while the other end is fixed on the other cable anchor (B); continuously testing the tensioning condition of the strand (13A), the condition involving in particular the measured values of the strand tension and of a predetermined parameter. The invention is characterized in that the predetermined parameter is the variation of the distance separating the cable anchors (A,B).

대표청구항 ▼

1. A method of tensioning a multiple strand cable in which said strands are installed one after the other between two cable anchors fastened to a structure, the method comprising the steps of:pulling on one end of a strand from one of the cable anchors with the other end fixed to the other cable anc

1. A method of tensioning a multiple strand cable in which said strands are installed one after the other between two cable anchors fastened to a structure, the method comprising the steps of:pulling on one end of a strand from one of the cable anchors with the other end fixed to the other cable anchor, measuring continuously the value of the tension in the strand, and continuously testing a condition for ending tensioning for the strand, said condition employing an expression that is a function of a predetermined parameter, wherein said predetermined parameter is the variation in the distance between said cable anchors. 2. A tensioning method according to claim 1, further comprising the steps of:a) determining the theoretical value of the zero tension length of the cable as a function of: the total number of strands of the cable, the axial stiffness and the weight per unit length of each of the strands of the cable, the theoretical position of the cable anchors as defined by drawings of the structure, the tension in the cable and the displacements of the cable anchors predicted by design computations for the structure for a predetermined reference phase occurring after tensioning the cable, b) evaluating the initial displacements of the cable anchors immediately before installing the first strand of the cable, c) during the tensioning of each strand of the cable: measuring continuously a distance variation from step b), executing a computation loop to test continuously the condition for ending tensioning the strand, using said expression which is a function of said predetermined parameter, and d) locking the strand being tensioned to the cable anchor as soon as the condition for ending tensioning of the strand is satisfied. 3. A tensioning method according to claim 2, wherein said expression which is a function of said predetermined parameter defines the stretch remaining to be applied to the strand until the condition for ending tensioning is satisfied.4. A tensioning method according to claim 3, wherein said expression is defined by the following parameters:i) the stiffness and the weight per unit length of the strand, ii) the theoretical zero tension length, iii) said initial displacements, iv) the tension measured in the strand, and v) said distance variation, and in that the strand is locked when the stretch remaining to be applied is equal to zero. 5. A tensioning method according to claim 4, wherein said expression is also defined by a value representing an insertion of keys by which said strand is anchored to its cable anchor.6. A tensioning method according to claim 2, wherein said expression which is a function of said predetermined parameter defines the locking tension that said strand must reach before it can be anchored.7. A tensioning method according to claim 6, wherein said expression is defined by the following parameters:i) the stiffness and the weight per unit length of the strand, ii) the theoretical zero tension length, iii) said initial displacements, iv) said distance variation, and wherein the strand is locked when the measured value of the tension applied to said strand becomes equal to that of the tension calculated in this way. 8. A method according to claim 2, wherein said initial displacements are measured on the structure by a procedure which factors in construction tolerances of said structure.9. A tensioning method according to claim 2, wherein said initial displacements are determined from the results of design computations for the structure.10. A tensioning method according to claim 2, wherein the cable includes a protective sheath and the method further comprises:i) determining the theoretical zero tension length from the weight per unit length of said sheath, and ii) during the computation relating to said condition for ending tensioning, increasing the weight per unit length of the strand being tensioned by a fraction of the weight per unit length of the sheath. 11. A tensioning method according to claim 2, further comprising factoring in the temperature of the strand being tensioned during step c) in the computation relating to said condition for ending tensioning.12. A tensioning method according to claim 2, further comprising factoring in the temperatures of the cables already installed on the structure and of the structure itself during step b) in the determination of said initial displacements.