FR3022291B1 - BENDING STIFFENER FOR AN EXTENSION ELEMENT INTENDED TO BE INTRODUCED INTO A RANGE OF WATER - Google Patents

Abstract

The stiffener (16) comprises: - a body (20) delimiting a central passageway (32) of the elongated element (14), with a central axis (A-A '), - an assembly (22; 24) for reinforcing the body (20), at least partially received in the body (20), the reinforcing assembly (22; 24) having at least one circumferential region extending around the central axis (A-A ') at least one measuring sensor (60) for deformation within the stiffener (16); The or each deformation measuring sensor (60) is carried by the reinforcing assembly (22; 24) of the body (20).

Description

Curvature stiffener for an elongated element intended to be introduced into a body of water

The present invention relates to a curvature stiffener for an elongate element intended to be introduced into a body of water, comprising: a body delimiting a central passage through the elongated element, of central axis; a reinforcement assembly of the body, at least partially received in the body, the reinforcement assembly including at least one circumferential region extending around the central axis; at least one sensor for measuring a deformation within the stiffener.

The stiffener is intended to be mounted around an elongated element intended to be introduced at least partially into a body of water, to limit the local curvature of a region of this element. The elongated element is, for example, a flexible pipe, in particular an unbonded flexible pipe intended for the transport of hydrocarbons through an expanse of water, such as an ocean, a sea, an lake or river.

A flexible pipe is for example made according to the normative documents API 17J (Specification for Unbounded Flexible Pipe) and API RP 17B (Recommended Practice for Flexible Pipe) established by the American Petroleum Institute.

The flexible pipe is generally formed of a set of concentric and superimposed layers. It is considered as "unbound" in the sense of the present invention since at least one of the layers of the pipe is able to move longitudinally relative to the adjacent layers during bending of the pipe. In particular, an unbonded pipe is a pipe devoid of binding materials connecting layers forming the pipe.

The conduit is generally disposed across an expanse of water between a bottom assembly for collecting fluid operated in the bottom of the body of water and a floating surface assembly for collecting and delivering fluid. The surface assembly may be a semi-submersible platform, an FPSO or other floating assembly.

When the conduct is subject to the effects of swell and sea currents, it is likely to deform locally. This is particularly the case at the connection of the flexible pipe to the surface assembly or to the bottom assembly, taking into account the relative movements between the pipe and the assembly to which it is connected.

In order for the pipe to retain a radius of curvature greater than its minimum acceptable radius of curvature ("MBR"), a stiffener, formed for example by a polymer body, is mounted around the pipe.

The stiffener locally limits the displacements of the pipe and guarantees the absence of local deformation beyond an acceptable limit.

However, the pipe remains highly stressed, even at the level of the stiffener. It is therefore relevant to follow over time the evolution of the deformations undergone by the stiffener and the conduct to ensure the integrity of the pipe.

To follow the evolution of the deformations undergone by the stiffener, it is known for example from WO 2009/156486 to mount around the stiffener a string of sensors arranged in a harness.

Such an assembly is very tedious to implement, disrupts the installation operations of the pipe and does not always reflect the exact deformation of the stiffener, let alone driving.

An object of the invention is to provide a non-intrusive system for monitoring the deformations of a stiffener disposed around an elongate element and / or an elongate element at a stiffener. For this purpose, the subject of the invention is a stiffener of the aforementioned type, characterized in that the or each deformation measuring sensor is carried by the reinforcement assembly of the body. The tip according to the invention may comprise one or more of the following characteristics, taken separately or in any combination technically possible: the reinforcement assembly comprises a framework at least partially embedded in the body, the framework comprising longitudinal reinforcing members, the longitudinal reinforcing members being advantageously connected to each other by a circumferential connecting member, at least one deformation measuring sensor being carried by the frame; at least one longitudinal reinforcing member carries a deformation measuring sensor; - The reinforcing assembly defines a receiving orifice of the deformation measuring sensor, the deformation measuring sensor being disposed in the receiving orifice; - It comprises a plurality of deformation measuring sensors within the stiffener, spaced apart from each other in the reinforcing assembly; at least two deformation measuring sensors are spaced longitudinally in the reinforcement assembly; at least two deformation measuring sensors are spaced radially or angularly with respect to the central axis in the reinforcement assembly; it comprises at least one line of deformation measuring sensors extending axially, radially or circumferentially around the central axis in the reinforcing assembly; the or each deformation measuring sensor comprises a strain gauge suitable for being powered electrically; the reinforcement assembly is metallic; it comprises at least one sensor for measuring the temperature carried by the reinforcing assembly. The invention also relates to a method of monitoring the behavior of a stiffener disposed around an elongated element, the method comprising the following steps: - providing a stiffener as defined above around the elongated element; measuring a deformation experienced by the stiffener with the aid of the or each deformation measuring sensor; - Advantageously, determining a local curvature of the stiffener, on the basis of the stress determined from the measurements made by the or each strain measurement sensor.

The method according to the invention may comprise one or more of the following characteristics, taken in isolation or in any technically possible combination: the stiffener comprises a plurality of spaced deformation measuring sensors in the reinforcement assembly; method comprising measuring the deformation experienced by each deformation measuring sensor; it comprises a step of dividing the stress obtained from the measurements made by the strain measurement sensors into three stress components comprising a membrane component, a flexural component, and a peak component, advantageously by a mathematical method constraint linearization; it comprises a step of validating a curvature profile of the stiffener determined on the basis of the stresses obtained from the deformation measurements carried out with the aid of the or each deformation measuring sensor, the validation step comprising the determining a type of load applied to the stiffener from at least one of the stress components obtained at the dividing step; it comprises a step of filtering the stress values obtained from the measurements made by the or each strain measurement sensor, to obtain filtered values of stress, then a step of determining a local deformation of the stiffener on the basis of filtered values of constraint. The invention will be better understood on reading the description which will follow, given solely by way of example, and with reference to the appended drawings, in which: FIG. 1 is a partial view, taken in section following a median axial plane, relevant parts of a fluid operating system having a curvature stiffener according to the invention; FIG. 2 is a partial perspective view of the internal framework of the curvature stiffener of FIG. 1; FIG. 3 is a side view of a longitudinal reinforcement member of the frame of FIG. 2, provided with a plurality of deformation measuring sensors spaced longitudinally from each other; - Figure 4 is a section along a transverse plane of the longitudinal reinforcement members of the frame of Figure 2, each provided with a plurality of deformation measuring sensors angularly spaced about the longitudinal axis; FIG. 5 is a view similar to FIG. 4, in which each longitudinal member is provided with a plurality of deformation measuring sensors spaced radially around the longitudinal axis; FIG. 6 illustrates a deformation measurement sensor formed by an electric macroscopic strain gauge; FIG. 7 illustrates a strain measurement sensor formed by a micrometric or nanometric stress gauge; FIG. 8 illustrates the division of the stress calculated from the measurements made by a series of three-component strain measurement sensors, using a stress linearization method, in a first treatment method according to FIG. 'invention.

The relevant parts of a first fluid operating installation 10 according to the invention across a body of water 12 are illustrated in FIG. 1. The body of water 12 is, for example, a sea, a lake or a an ocean. The depth of the water extent 12 to the right of the fluid operating installation 10 is for example between 500 m and 3000 m. The fluid operating installation 10 comprises a set of surface, in particular floating, and a set of bottom (not shown). The installation 10 comprises an elongated element 14 connecting the bottom assembly to the surface assembly and at least one curvature stiffener 16 according to the invention, mounted around a section of the elongated element 14. The assembly surface comprises a connector (not shown) for connecting the elongated element 14, and advantageously, as illustrated in Figure 1, a mounting member 18 of the stiffener 16, on which the stiffener 16 is intended to be fixed. The mounting element 18 is for example a guide tube of the elongate element 14, such as an I-tube or a J-tube, projecting downwards in the body of water 12.

In this example, the elongated element 14 is a flexible pipe.

Examples of flexible piping are described in the normative documents published by the American Petroleum Institute (API), API 17J, and API RP17B.

The flexible pipe delimits a plurality of concentric layers around the axis A-A ', in particular at least a first sheath based on polymeric material advantageously constituting a pressure sheath and at least one layer of tensile armor disposed externally relative to at the first sheath.

The curvature stiffener 14 comprises a body 20 of revolution about an axis A-A 'of the elongated element 14. It further comprises a reinforcement assembly of the body 20, comprising an internal reinforcing metal frame 22 of the body 20 , at least partially embedded in the body 20, and advantageously, a peripheral insert 24 disposed in the body 20.

Advantageously, the curvature stiffener 16 further comprises a flange 26 for connection to the mounting element 18, fixed on the internal framework 22 and on the insert 24.

According to the invention, the curvature stiffener 16 comprises an instrumentation 27 for monitoring the local deformation of the body 20, carried partially by the reinforcing assembly.

The body 20 is made of a more rigid material than the elongated element 14. It is for example made of plastic material, especially polyurethane.

The body 20 is intended to limit the bending amplitude of the elongated element 14 at the section received in the body 20, to define a minimum radius of curvature without plastic deformation (or "MBR") minimum at this section .

The minimum radius of curvature is for example greater than 3 m.

The body 20 here comprises a substantially cylindrical upper section 28 and a frustoconical lower section 30 of decreasing cross-section away from the upper section 28.

The length of the body 20 taken along the axis A-A 'is for example between 500 mm and 8 m.

The body 20 delimits an axial through-passing through hole 32 of the elongated element 14, opening at the axial ends of the body 20. The frame 22 is at least partially embedded in the body 20. It is made of metal. The frame 22 comprises a plurality of longitudinal reinforcement members 34 held in position relative to one another by being fixed to the connection flange 26.

The reinforcing members 34 are angularly separated from one another. They delimit between them intermediate spaces folded by the body 20.

Optionally, in the particular example illustrated in Figure 2, the frame 22 further comprises a circumferential connecting member 36 connecting the longitudinal members 34 between them.

Each longitudinal member 34 extends along an axis B-B '(visible in Figure 3) substantially parallel to the axis A-A'. It is preferably arranged in the cylindrical portion 28 of the body 20.

Each longitudinal member 34 comprises a base 38, a longitudinal frame 40, and a head 42 for assembling the flange 26, delimiting the free end of the longitudinal member 34.

In this example, the base 38 tapers away from the connection flange 26.

The longitudinal chord 40 is embedded in the body 20, away from the inner peripheral surface and the outer peripheral surface of the body 20.

The head 42 protrudes from the frame 40 out of the body 20. It advantageously comprises a thread, to allow the attachment of a bolt 44 retaining the flange 26, visible in Figure 1.

In the example of FIG. 2, when it is present, the circumferential connecting member 36 comprises a closed torus of axis A-A '. The circumferential connecting member 36 forms a circumferential region of the reinforcement assembly.

The circumferential region extends around the axis A-A 'over an angular extent greater than 90 °, in particular greater than 180 ° and equal to 360 °. It is located radially away from the axis A-A '. The circumferential connecting member 36 is here completely embedded in the body 20 being disposed away from the inner peripheral surface, the outer peripheral surface and the upper transverse surface of the body 20.

In this particular case, the base 38 of each longitudinal member 34 is integral with the circumferential member. Each longitudinal member 34 protrudes axially from the circumferential member 36. The peripheral insert 24 is advantageously metallic. It comprises an inner skirt 50 disposed in the body 20 at the periphery of the axial slot 32, in the upper portion 28 of the body 20, an outer skirt 52 disposed on the outer peripheral surface of the body 20, and a transverse outer wall 54 connecting the inner skirt 50 to the outer skirt 52.

The skirts 50, 52 are of revolution about the axis A-A ', circumferentially around the axis A-A'.

They are interconnected by their outer edges, through the outer wall 54. The outer wall 54 is applied to the outer transverse surface of the body 20.

Each skirt 50, 52 forms a circumferential region of the reinforcement assembly.

The circumferential region extends around the axis A-A 'over an angular extent greater than 90 °, in particular greater than 180 ° and equal to 360 °. It is located radially away from the axis A-A '.

The connection flange 26 here comprises a cylindrical base 56 pressed against the inner skirt 50 of the insert 24, and a connecting collar 58, of revolution about the axis A-A '. The cylindrical base 56 and the connecting flange 58 form only one piece.

The heads 42 of the longitudinal members 34 are inserted through the outer wall 54 and the flange 58. The bolts 44 hold the insert 24 and the connecting flange 26 pressed against the outer transverse surface of the body 20.

As mentioned above, the connection flange 26 forms a circumferential connection member between the reinforcing members 34. The instrumentation 27 comprises a plurality of deformation measuring sensors 60, which are here borne by the frame 22, and a processing unit 62 connected to the strain measurement sensors 60.

The strain measurement sensors 60 are electrical or optical sensors. They are able to generate an electrical or optical signal representative of the local deformation generated by a (or) constraint (s) applying to the stiffener 16.

In the example illustrated in FIG. 6, each strain measurement sensor 60 is formed by a macroscopic strain gauge or resisitive strain gauge, of size greater than 1 mm, and advantageously smaller than 30 mm, which is received in an orifice formed in the frame 22. For example, the resistive strain gauge is a gauge with metal or semiconductor frames.

In a variant shown in FIG. 7, the sensors are microsensors or nanosensors which are integrated in the form of a metal layer on the surface or in the body of the framework 22. The sensors are, for example, Wheatstone bridges 66 or resistors 68 with an integrated circuit.

In addition, each deformation measuring sensor 60 of the optical sensor type is for example an optical fiber sensor in which Bragg gratings are printed.

In another variant, each strain measurement sensor 60 is an inductive type displacement sensor such as a sensor of the linear variation differential converter (LVDT) type (Linear Variable Differential Transformer), a frequency-type sensor. such as a vibrating wire sensor or a capacitive type sensor.

The limits of use of each of the sensors are mainly defined by its qualities of precision and resolution.

The accuracy of a sensor is defined by the percentage difference that can be obtained between the actual value and the measured value at the output of the sensor. The smaller the gap, the more accurate the sensor.

In addition, the resolution of a sensor corresponds to the smallest variation of the quantity to be measured, which the sensor is able to detect.

For example, if one considers a deformation measurement sensor 60 of the vibrating wire type, with regard to its limits of use as well as the mechanical properties of the element on or in which it is arranged, in our case, the body of the frame 22 or the longitudinal members 64, it is possible to deduce the accuracy and the resolution that can be obtained.

Depending on the type of measurements that one wishes to acquire, the quality of precision that can be obtained for this type of sensor is in a range of values of the order of ± 0.5%, in particular ± 0 , 25%. Moreover, the quality of the resolution that can be obtained is of the order of a few tenths of micrometers, in particular of the order of 1 micrometer.

In the embodiments illustrated in FIGS. 3 to 5, the strain measurement sensors 60 are carried by the longitudinal members 34.

In the example shown in FIG. 3, the deformation measuring sensors 60 are spaced longitudinally from one another along the axis B-B 'of each longitudinal member 34. In this example, the deformation measuring sensors 60 are further arranged along a line parallel to or coincident with the axis B-B '.

The linear density of sensors 60 along the axis B-B 'is for example between 1 sensor per millimeter and 1 sensor per 10 millimeter.

The presence of a plurality of deformation measuring sensors 60 spaced longitudinally from each other enriches the information obtained with the aid of the instrumentation 27, to determine a stress profile applying along each longitudinal member 34.

Advantageously, the strain measurement sensors 60 are further spaced angularly about the axis A-A 'in a cross section relative to the axis B-B', as illustrated in FIG. 4.

In a variant, or in addition, the strain measurement sensors 60 are spaced radially with respect to the axis A-A 'in a cross section relative to the axis B-B', as illustrated by FIG. 5.

Advantageously, at least one first group of deformation measuring sensors 60, located at a first height along the axis B-B ', is arranged in the configuration of FIG. 4, with an angular spacing around the axis A-A '. At least a second group of strain measuring sensors 60, located at a second height along the axis B-B ', is arranged in the configuration of FIG. 5, with a radial spacing between the sensors 60.

In another variant not shown, the strain measurement sensors 60 are carried by the circumferential connecting member 36.

With reference to FIG. 1, the processing unit 62 comprises a processing processor and a memory containing a module 80 for receiving the instantaneous deformation measurements taken by the strain measurement sensors 60, a module 82 for storing the received measurements. , and a module 84 for calculating an instantaneous local curvature of the stiffener 16, on the basis of the measurements received. The processing unit 62 furthermore advantageously comprises a strain linearization module 86 along the successive sections of each longitudinal member 34, and a module 88 for validating the data obtained by the calculation module 84 on the basis of the linearization of constraint carried out along the successive sections.

The receiving module 80 is adapted to receive, at a selected frequency, for example between one measurement per second and one hundred measurements per second, the measurements received from each measurement sensor 60 of the instrumentation. assign to each of the received measurements location information of the sensor 60 and information relating to the moment at which the measurement is made.

The storage module 82 is able to store all the instantaneous measurements received by the module 80, with a view to their instantaneous or subsequent processing.

The calculation module 84 is able to establish from the measurements made by each sensor 60 at a given moment a mapping of the stresses undergone by and along the longitudinal members 34 and therefore to determine the curvature profile of the stiffener 16 along each longitudinal member 34 at this given instant, on the basis of a mathematical model.

Advantageously, the calculation module 84 comprises a data filter, capable of eliminating measurements of amplitude less than a predefined constraint threshold, in order to limit the processing time by the processor, in particular for instantaneous processing.

The linearization module 86 is capable of dividing the total stress obtained from the measurements of each sensor 60 at a given instant into three components comprising a membrane component M, a flexural component B, and a peak component P (visible on Figure 8), by a mathematical method of constraint linearization.

The validation module 88 is able to determine the type of initial load applied at a given moment on the stiffener 16, on the basis of the values of the three components Μ, B, P obtained from the linearization module 86.

The validation module 88 is thus able to determine whether the applied load is axial or transverse. For example, a flat curvature profile dominated by the membrane component M is representative of an axial load. In contrast, a curvature profile curved and dominated by flexural component B is representative of a transverse load.

The validation module 88 is thus able to remove any ambiguity on the curvature profile calculated from the constraints established from the measurements made by each strain measurement sensor 60, in the case where several curvature profiles are susceptible to generate the same stress distribution, depending on the type of load applied.

In a variant, since the type of initial load applied at a given instant on the stiffener 16 has been determined by the validation module 88, this data is entered in the input parameters of a program of a software package. finite element calculation (or FEA "Finite Element Analysis" in English). The program is then started and the results of the analysis are awaited, the results making it possible to model and calculate the deformations generated by the previously determined load and hence the curvature profile of the stiffener 16.

The constraint linearization method works as a comparison and validation tool when used in parallel with finite element calculation software, as well as as a full-fledged tool for directly obtaining the curvature profile of the device. stiffener 16 when used synergistically with the finite element calculation software.

A method of monitoring the behavior of a stiffener 16 according to the invention, arranged around an elongated element 14, will now be described.

Initially, a stiffener 16 as described above is provided and is installed around the elongated element 14. The stiffener 16 is immobilized on the mounting element 18.

Advantageously, the elongated element 14 is connected to a connector on the surface assembly.

During the installation, or after it, the method comprises, at each measurement instant at a frequency advantageously between one measurement per second and one hundred measurements per second, a step of measuring the local deformations undergone by the stiffener 16, with each deformation measuring sensor 60, and receiving each measurement made by the receiving module 80 of the processing unit 62.

The measurements received by the reception module 80 are then stored in the memory by the storage module 82 so that they can be used either instantaneously in real time or later on the ground, if all the measurements received by the module reception 80 is too large to be used in real time.

If a real-time processing is desired, a data filtering step is advantageously carried out using a filter to retain the measurements of greater value for example at a given threshold of stress. Thus, the calculation power required in the processor of the processing unit 62 is reduced.

Next, a step of calculating a curvature profile of the stiffener 16 is implemented. A mathematical model is used by the calculation module 84 to determine a curvature profile of the stiffener 16 around the frame 22, advantageously along each longitudinal member 34, on the basis of a stress mapping established from the measurements. obtained by the deformation measuring sensors 60 spaced along the longitudinal member 34. For this purpose, at at least a given measurement instant, the local curvature of the stiffener 16 is calculated, on the basis of the individual values measured by each deformation measuring sensor 60 in each determined position along the longitudinal member 34.

This makes it possible to obtain a curvature profile of the stiffener 16 along each longitudinal member 34.

In parallel, each total stress obtained from the measurements made by a strain measurement sensor 60 is divided into several components Μ, B, P, by a mathematical method of stress linearization.

For each given position of a strain measurement sensor 60, at the given instant, the linearization module 86 divides the total stress obtained into three components, namely a membrane component M, a flexural component B, and a peak component P, by a mathematical method of constraint linearization.

Thus, the linearization module 86 establishes a profile of each component Μ, B, P along the longitudinal member 34, as illustrated in FIG. 8.

Then, a validation step of the curvature profile calculated by the calculation module 84 in the calculation step is performed.

The validation module 88 first establishes the type of load applied longitudinally on the stiffener 16.

This choice is made on the basis of the components Μ, B, P obtained by linearization at the division stage. The value of each component Μ, B, P, as well as its distribution along the longitudinal member 34 is advantageously correlated with the type of initial charge.

The type of initial charge is chosen for example from an axial load and a transverse load.

An axial load generally has a membrane component M of greater value than the flexural components B and P, and a substantially flat distribution. Conversely, a transverse load generally has a flexural component B greater than the other components Μ, P and a curved distribution.

The validation module 88 thus assigns a type of load applied to the stress profile determined from the deformation measurements made by the strain measurement sensors 60, on the basis of the components Μ, B, P obtained by linearization at step of division. This removes any ambiguity on the possible curvature profile resulting from the measured stress profile.

Thus, even if different profiles of curvature can result from the same distribution of stresses along the longitudinal member 34, the determination of the type of load applying to the longitudinal member 34 makes it possible to differentiate between the different profiles of possible curvature. .

The calculated curvature profile, once validated, makes it possible to follow continuously the degree of stress applied to the stiffener 16, during the life of the stiffener 16, and to possibly deduce the fatigue of the stiffener and / or the elongated element 14 received in the stiffener 16, by modeling.

The stiffener 16 according to the invention is instrumented without changing the structure of the body 20 of the stiffener 16 or the structure of the elongated element 14. Thus, the geometry and the dimensions of the stiffener 16 are kept constant, which facilitates the practical use stiffener and avoids at least some requalification steps.

The arrangement of the sensors 60 within the frame 22, and in particular in the longitudinal members 34 of the frame 22 allows an accurate determination of the stress field, and as a result of the variations of the curvature profile undergone over time by the stiffener 16.

The method according to the invention applies equally in any position of the stiffener 16, that the stiffener 16 is under water or on the surface.

The monitoring of the curvature variations of the stiffener 16 is advantageously validated by the determination of the linearized components Μ, B, P of the stress, by performing a constraint linearization.

In one variant, the calculations for determining the curvature profile are made a posteriori, away from the stiffener 16 in a processing unit 62 that is offset from the stiffener 16. In this case, the measurement data are not necessarily filtered. .

In a variant, at least one temperature measuring sensor, for example a vibrating wire sensor, a thermocouple or a resistive temperature sensor is disposed in the framework 22 and / or in the insert 50 in the vicinity of a strain measurement sensor 60 for providing temperature data to the mathematical model for calculating curvature profiles. The temperature measurement sensor makes it possible to estimate from which temperature value the stiffener 16 begins to degrade.

In a variant, the sensors 60 are arranged in the insert 50, in particular in the skirt 50, being spaced longitudinally and / or angularly about the axis A-A '.

Claims (15)

1. - Curvature stiffener (16) for an elongated element (14) intended to be introduced into a body of water (12) comprising: - a body (20) delimiting a central lumen (32) for passage of the element elongate (14), of central axis (A-A '); an assembly (22; 24) for reinforcing the body (20), at least partially received in the body (20), the reinforcement assembly (22; 24) having at least one circumferential region extending around the central axis (A-A '); at least one measuring sensor (60) for a deformation within the stiffener (16); characterized in that the or each deformation measuring sensor (60) is carried by the reinforcing assembly (22; 24) of the body (20), and in that the reinforcing assembly (22; 24) is metallic . 2. - stiffener (16) according to claim 1, characterized in that the reinforcing assembly (22; 24) comprises a frame (22) at least partially embedded in the body (20), the frame (22) comprising longitudinal reinforcing members (34), the longitudinal reinforcing members (34) being advantageously connected to each other by a circumferential connecting member (26, 36), at least one deformation measuring sensor (60) being carried by the frame (22). 3. - Stiffener (16) according to claim 2, characterized in that at least one longitudinal reinforcing member (34) carries a deformation measuring sensor (60). 4. - Stiffener (16) according to any one of the preceding claims, characterized in that the reinforcing assembly (22; 24) defines a receiving orifice of the deformation measuring sensor (60), the measuring sensor of deformation (60) being disposed in the receiving orifice. 5. - Stiffener (16) according to any one of the preceding claims, characterized in that it comprises a plurality of strain measurement sensors (60) within the stiffener (16), spaced apart from each other in the reinforcement assembly (22; 24). 6. - Stiffener (16) according to claim 5, characterized in that at least two deformation measuring sensors (60) are spaced longitudinally in the reinforcing assembly (22; 24). 7. - stiffener (16) according to any one of claims 5 or 6, characterized in that at least two deformation measuring sensors (60) are spaced radially or angularly relative to the central axis (A-A) ') in the reinforcing assembly (22; 24). 8. - Stiffener (16) according to any one of claims 5 to 7, characterized in that it comprises at least one line of deformation measuring sensors (60) extending axially, radially or circumferentially around the central axis (A-A ') in the reinforcing assembly (22; 24). 9. - Stiffener (16) according to any one of the preceding claims, characterized in that the or each deformation measuring sensor (60) comprises a strain gauge capable of being electrically powered. 10. - Stiffener (16) according to any one of the preceding claims, characterized in that it comprises at least one sensor for measuring the temperature carried by the reinforcing assembly (22; 24). 11. - A method of monitoring the behavior of a stiffener (16) disposed around an elongated element (14), the method comprising the following steps: - providing a stiffener (16) according to any one of the preceding claims around the elongate member (14); measuring a deformation experienced by the stiffener (16) with the aid of the or each deformation measuring sensor (60); advantageously, determination of a local curvature of the stiffener (16), on the basis of the stress determined from the measurements made by the or each strain measurement sensor (60). Method according to claim 11, characterized in that the stiffener (16) comprises a plurality of deformation measuring sensors (60) spaced apart in the reinforcing assembly (22; 24), the method comprising the measurement of the deformation experienced by each deformation measuring sensor (60). 13. - Method according to claim 12, characterized in that it comprises a step of dividing the stress obtained from the measurements made by the strain measurement sensors (60) into three stress components comprising a membrane component, a bending component, and a peak component, advantageously by a mathematical method of constraint linearization. 14. - Method according to one of claims 11 to 13, characterized in that it comprises a step of validating a curvature profile of the stiffener (16) determined on the basis of the stresses obtained from the deformation measurements carried out with the or each deformation measuring sensor (60), the validation step comprising determining a type of load applied to the stiffener (16) from at least one of the stress components obtained at the division stage. 15. - Method according to any one of claims 11 to 14, characterized in that it comprises a step of filtering the stress values obtained from the measurements made by the or each strain measurement sensor (60), to obtain filtered strain values, and then a step of determining a local deformation of the stiffener (16) based on the filtered strain values.