Cable force measurement and health monitoring system of cable net curtain wall

Abstract

The invention relates to the field of constructional engineering, and particularly discloses a cable force measurement and health monitoring system for a cable net curtain wall. The stay wire type displacement sensors are arranged on all steel cables or a key part steel cable area of the cable net curtain wall structure, the two ends of the sensor stay wire and the two ends of a steel cable body are arranged on the same point position, and the sensor stay wire passes through a stay wire sliding groove in a glass grabbing clamp; when glass on a curtain wall is stressed to drive the glass gripper to transversely move, the glass gripper drives the steel cable body and the sensor stay wire to synchronously deform, and the stay wire type sensor can measure the elongation of the sensor stay wire due to the fact that the sensor stay wire can longitudinally slide and extend in the glass gripper. The elongation of the sensor stay wire is the deformation elongation of the steel cable body, the deformation increased cable force of the steel cable body is calculated according to the material elasticity theory of the steel cable body material, and the total cable force of the steel cable body is the sum of the prestress and the deformation increased cable force, so that the change condition of the cable force increment is measured.

Description

Technical Field

[0001] The invention belongs to the technical field of building engineering, and in particular relates to a cable force measurement and health monitoring system for a cable net curtain wall. Background Art

[0002] With the development of modern construction industry, people have higher and higher requirements for the use function, aesthetic effect and comfort of building structure. A kind of beautiful, light-permeable, green and low-carbon curtain wall structure - prestressed steel cable net curtain wall structure has emerged and has been widely praised and paid attention to. The curtain wall structure uses high-strength steel wire twisted by complex and special process to form high-strength prestressed steel cable as the glass bearing component. Because the prestressed steel cable has high strength (1320Mpa~1770Mpa, which is 4~6 times the strength of ordinary steel), small size and beautiful appearance (steel wire can be made of stainless steel or high vanadium coated carbon steel, etc., in short, the exposed metal feeling of steel wire is strong), as a kind of prestressed steel cable of cable component, it is applied to the cable net curtain wall structure system. Therefore, the cable net curtain wall has distinct flexible structural characteristics, namely large span, small component (small volume, cross-sectional bending stiffness is almost 0), strong bearing capacity, and also has the characteristics of large influence of cable force on structural stiffness and large deformation.

[0003] Because the cross-sectional stiffness of a single cable component is small, the overall stiffness of the structure requires the interaction of other cable components (and also influences each other) and reaches a certain cable tension level before it is formed. Therefore, the overall stiffness of the structure is greatly affected by the cable tension level of a single cable component. This is very obvious both in the construction stage and in the use stage of the curtain wall structure. That is, the cable tension level of the cable component directly determines the working capacity of the cable net curtain wall structure system. For example, if the cable tension of the cable component is applied incorrectly during the construction stage or the local cable tension is naturally relaxed during the use stage, the stiffness of the curtain wall system is redistributed, which will lead to defects such as excessive or insufficient local cable tension and excessive local deformation in the curtain wall system, which will lead to local glass breakage or, in more serious cases, the curtain wall system will lose its ability to continue to be used. In addition, it will also have a certain impact on the surrounding main structure.

[0004] In summary, the cable tension level of cable components in the cable net curtain wall structure system is the prerequisite for ensuring the normal and effective operation of the structural system. Therefore, whether it is in the construction stage or the use stage, whether the cable tension level of each cable can be obtained conveniently and accurately is the key to ensuring the quality and safety of the project.

[0005] Existing monitoring schemes for cable net curtain walls mainly focus on monitoring the cable tension and comparing it with the designed cable tension. If the difference between the two exceeds a preset threshold, that is, the deviation between the curtain wall cable tension and the designed cable tension exceeds the allowable range, the cable curtain wall structure is considered to be in an "unsafe state". However, it is not easy to quickly and conveniently obtain the cable tension of a cable curtain wall in use.

[0006] At present, the more mature methods for measuring prestressed steel cables include the oil gauge reading method, the frequency method, the weighing sensor method, the magnetic flux sensor method and the buried fiber grating method. The oil gauge reading method is to read the cable tension at the tensioning end of the prestressed steel cable through the tensioning equipment used in the tensioning process of the prestressed steel cable construction - the jack and the oil gauge. After the building is completed and the equipment is removed, the cable tension measurement becomes extremely difficult and costly. In addition, because this method can only measure the cable end of the tensioning equipment, but cannot measure the cable tension at any part of the cable body, this method is only limitedly used in the measurement of the cable tension at the end during the construction process; the frequency method is a method developed by using the physical relationship between the cable tension in the prestressed steel cable and its cable tension. This method is a cable tension detection method, but the measurement object of this method is limited to simply supported cables without other interference objects. If the cable body is connected to other building components, such as other cables, steel beams, struts, etc., the natural frequency of the detected cable itself will be distorted due to the "interference" of other components. At this time, this method becomes unfeasible; the weighing sensor method refers to burying a weighing sensor at the end of the prestressed steel cable, transmitting the prestressed steel cable force through its structure, and thus measuring the prestressed steel cable force. Like the oil gauge reading method, this method requires the equipment to be buried in a fixed position of the cable and participate in the cable force. Therefore, it is limited to the cable force measurement at the buried position and is costly; the magnetic flux method uses the detected object-prestressed The magnetostrictive effect of the steel cable, that is, the change of the steel cable stress will cause the change of the steel cable magnetic permeability, thereby causing the change of the physical quantity of the external magnetic field. By measuring the changing physical quantity of the magnetic field and using the monotonic relationship between the steel cable stress and the physical quantity of the magnetic field, the corresponding steel cable stress (cable force) is obtained. This method is limited to carbon steel cables (stainless steel cable force has no magnetic conductivity, so it is not applicable), and complex calibration is required before the magnetic flux method measurement. The accuracy of the measurement depends largely on the calibration data before implementation, which is costly. In addition, the magnetic flux sensor is placed on the outside of the prestressed steel cable, and its outer diameter is generally 50-100mm larger than the diameter of the measured cable body, and the height is generally 200mm-300mm. mm, which is equivalent to putting an "iron column" on the steel cable. This "iron column" is not easy to "hide" in the relatively transparent cable curtain wall, which is somewhat contrary to the original intention of architects to design the cable curtain wall. They use the curtain wall of steel cables with a bearing capacity 5 to 10 times higher than that of ordinary steel parts to reduce the size of the curtain wall structural components to obtain a relatively "unobstructed" wide field of view; the embedded fiber grating sensor method is to implant one or several fiber grating sensors in the cable body in advance, and it is believed that the deformation of the fiber grating is synchronized with the deformation of the prestressed steel cable (or there is a certain constant mapping relationship), so the cable force of the prestressed steel cable can be "inferred" by the deformation of the fiber grating.This method is a new technology developed in recent years, and its scale and scope of use are not wide, especially in cable curtain wall structures. In addition, this method actually implants sensors inside the cable body (but the fiber grating sensor is small in size and its impact on the force performance and appearance of the cable body is almost negligible), but it places high demands on the twisting of the cable body, casting of anchors, transportation of the cable body, installation and other links.

[0007] Among the five methods of measuring cable tension mentioned above, the last three are to first "integrate" sensors in the measured cable tension (hereinafter referred to as "integrated sensor method"), and measure the tension of prestressed steel cables in the cable curtain wall through sensors. This "integrated sensor method" has a common disadvantage, that is, the process of maintaining and replacing sensors is extremely cumbersome and the cost is quite staggering, which greatly reduces the benefits brought by the health monitoring of the cable curtain wall. The following takes the magnetic flux sensor method as an example to describe the brief process of replacing the sensor: According to the principle and characteristics of the magnetic flux sensor method, the magnetic flux sensor is placed on the cable body to be measured before the cable body and anchor are cast. Once the anchor is cast, the sensor cannot be completely removed. If the sensor is to be removed, the anchor at the end of the cable body must be removed. For the cable net curtain wall in use, if you want to remove the sensor on the measured cable, you need to use the opposite process of the installation process to remove them one by one. The removal process is as follows: remove the glass → release the cable force → remove the sensor cable body → remove the cable anchor → remove the sensor → cast the cable body and anchor → install the replaced cable body → tension the replaced cable body → install the glass → others. It should be noted that the "removal of the cable anchor" and "casting the cable body and anchor" in the above-mentioned replacement process need to be carried out in the original factory, and cannot be implemented on site. Therefore, the sensor maintenance and replacement of this method is extremely cumbersome, and the economic benefits are greatly reduced.

[0008] In summary, all the difficulties in curtain wall cable net curtain wall health monitoring are that it is impossible to efficiently and accurately obtain the cable tension of the prestressed steel cable, and then realize the safety assessment of the cable tension of the prestressed steel cable. In the above-mentioned traditional cable tension measurement methods, either it is impossible to measure automatically in real time, such as the oil gauge reading method is limited to manual operation during the construction process; or the measurement data is inaccurate, such as the measurement conditions of the frequency method cannot be met, and the obtained data is not accurate enough and cannot be used as an evaluation basis; although the latter three sensor methods can meet the requirements of curtain wall health monitoring in terms of data acquisition methods and credibility, the sensors are integrated with the measured cables, which has a great impact on the layout of the sensors and the appearance of the building, and the commercial cost is relatively high. What is more fatal is that the "integrated sensor method" brings great difficulties to the maintenance, repair, and replacement of the monitoring system. Therefore, it is necessary to redesign a monitoring system that can efficiently and accurately measure the cable tension of prestressed steel cables. Summary of the invention

[0009] In order to overcome the deficiencies of the prior art, an object of the present invention is to provide a cable tension measurement and health monitoring system for a cable net curtain wall, so as to solve the problem that the existing measurement method cannot accurately and efficiently measure the tension of prestressed steel cables at a low cost.

[0010] To achieve the above object, the present invention provides the following technical solutions:

[0011] A cable force measurement and health monitoring system for a cable net curtain wall, comprising:

[0012] The lower frame of the curtain wall-cable anchoring point is arranged on the lower frame of the cable net curtain wall, and the lower frame of the cable net curtain wall is fixedly connected with a steel cable tensioning end anchor at the lower frame of the curtain wall-cable anchoring point;

[0013] The upper frame-cable anchoring point on the curtain wall is arranged on the upper frame of the cable net curtain wall, the upper frame of the cable net curtain wall is fixedly connected with a steel cable fixed end anchor at the upper frame-cable anchoring point on the curtain wall, a steel cable body is fixedly connected between the steel cable fixed end anchor and the steel cable tensioning end anchor, and a glass claw for fixing the glass is fixedly connected to the steel cable body;

[0014] A pull-wire displacement sensor storage box is connected to the anchor at the tensioning end of the steel cable, an outlet end of the pull-wire displacement sensor storage box is connected to an extendable sensor pull wire, and a pull-wire displacement sensor for collecting the stretched length of the sensor pull wire is arranged inside the pull-wire displacement sensor storage box;

[0015] The fixed end of the sensor pull wire head is arranged on the anchor of the fixed end of the steel cable. The sensor pull wire passes through the pull wire slide groove on the glass grab clamp and is fixedly connected to the fixed end of the sensor pull wire head.

[0016] Preferably, the sensor wire is parallel to the steel cable body.

[0017] Preferably, the sensor pull wire is in contact with the inner wall of the pull wire slide groove and slides along the axis center line direction of the pull wire slide groove.

[0018] Preferably, the displacement measurement accuracy of the draw-wire sensor is greater than seven microns.

[0019] Preferably, the pull-wire sensor is connected to a host computer, and the host computer has a built-in algorithm, which is used to calculate the elongation of the steel cable body according to the stretched length of the sensor pull wire, and then calculate the cable force of the steel cable body according to the elongation of the steel cable body.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] The present invention arranges a wire-drawing displacement sensor on all the steel cables or the steel cable areas at key parts of the cable net curtain wall structure, and sets the two ends of the sensor wire of the wire-drawing displacement sensor at the same point as the two ends of the steel cable body, and the sensor wire passes through a wire-drawing slide groove on the glass clamp. When the glass on the curtain wall is subjected to force and drives the glass clamp to move laterally, the glass clamp drives the steel cable body and the sensor wire to deform synchronously. Since the sensor wire can slide and stretch longitudinally inside the glass clamp, the wire-drawing sensor can measure the elongation of the sensor wire at this time. The elongation of the sensor wire is the deformation elongation of the steel cable body. Then, the deformation-increased cable force of the steel cable body is calculated according to the material elasticity theory of the steel cable body material. At this time, the total cable force of the steel cable body is the prestress plus the deformation-increased cable force. The change of the cable force increment is measured in this way, and then the safety performance of the curtain wall structure is diagnosed or evaluated, and the risk identification and safety warning of the cable net curtain wall structure in the whole life cycle are realized, that is, the health monitoring of the cable net curtain wall is realized, which is convenient for guiding the use, maintenance and repair of the cable net curtain wall structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the overall structure of the system of the present invention;

[0023] Figure 2 It is a cross-sectional view of the matching structure of the glass grabbing clamp and the sensor wire of the present invention;

[0024] In the figure: 1. Wire storage box for pull-wire displacement sensor; 2. Sensor pull-wire slideway; 3. Sensor pull-wire; 4. Sensor pull-wire head and fixed end; 5. Cable anchorage point at lower frame of curtain wall; 6. Anchor at the tensioning end of steel cable; 7. Glass gripper; 8. Steel cable body; 9. Anchor at the fixed end of steel cable; 10. Cable anchorage point at upper frame of curtain wall. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] Example:

[0027] See also Figure 1 - Figure 2 As shown, a cable force measurement and health monitoring system for a cable net curtain wall comprises:

[0028] The lower frame of the curtain wall-cable anchoring point 5 is arranged on the lower frame of the cable net curtain wall, and the lower frame of the cable net curtain wall is fixedly connected with a steel cable tensioning end anchor 6 at the lower frame of the curtain wall-cable anchoring point 5;

[0029] The upper frame-cable anchor point 10 of the curtain wall is arranged on the upper frame of the cable net curtain wall, and the upper frame of the cable net curtain wall is fixedly connected with a steel cable fixed end anchor 9 at the upper frame-cable anchor point 10 of the curtain wall, and a steel cable body 8 is fixedly connected between the steel cable fixed end anchor 9 and the steel cable tensioning end anchor 6, and a glass claw 7 for fixing the glass is fixedly connected to the steel cable body 8;

[0030] A pull-wire displacement sensor storage box 1 is connected to the anchor 6 at the tensioning end of the steel cable, an outlet end of the pull-wire displacement sensor storage box 1 is connected to an extendable sensor pull wire 3, and a pull-wire displacement sensor for collecting the stretched length of the sensor pull wire 3 is arranged inside the pull-wire displacement sensor storage box 1;

[0031] The sensor wire head fixed end 4 is arranged on the steel cable fixed end anchor 9 , and the sensor wire 3 passes through the wire slide groove 2 on the glass grab 7 and is fixedly connected to the sensor wire head fixed end 4 .

[0032] As can be seen from the above, a pull-wire displacement sensor storage box 1 and a pull-wire displacement sensor are arranged on all the steel cables or the steel cable areas of the key parts of the cable net curtain wall structure, and the two ends of the sensor pull wire 3 of the pull-wire displacement sensor are respectively set at the same point as the two ends of the steel cable body 8, that is, the two ends of the sensor pull wire 3 can be set on the steel cable fixed end anchor 9 and the steel cable tensioning end anchor 6, and the sensor pull wire 3 passes through the pull wire slide groove 2 on the glass gripper. When the glass on the curtain wall is forced to drive the glass gripper 7 to move horizontally, the glass gripper 7 drives the steel cable body 8 and the sensor pull wire 3 to deform synchronously. Since the sensor pull wire 3 can be on the glass The glass gripper 7 slides and stretches longitudinally inside, and at this time, the wire sensor can measure the elongation of the sensor wire 3, and the elongation of the sensor wire 3 is the deformation elongation of the steel cable body 8. Then, according to the material elasticity theory of the steel cable body 8 material, the deformation-increased cable force of the steel cable body 8 is calculated. At this time, the total cable force of the steel cable body 8 is the prestressed force plus the deformation-increased cable force. The change of the cable force increment is measured in this way, and then the safety performance of the curtain wall structure is diagnosed or evaluated, and the risk identification and safety warning of the cable net curtain wall structure throughout the life cycle, that is, the health monitoring of the cable net curtain wall, is realized, which is convenient for guiding the use, maintenance and repair of the cable net curtain wall structure.

[0033] In order to make the elongation of the sensor wire 3 equal to the elongation of the steel cable body 8, the sensor wire 3 is parallel to the steel cable body 8. At this time, the deformation heights of the sensor wire 3 and the steel cable body 8 are similar, and the elongation of the sensor wire 3 can be equated with the elongation of the steel cable body 8.

[0034] Reference Figure 2The sensor wire 3 fits the inner wall of the wire slide 2 and slides along the axial centerline of the wire slide 2, that is, the sensor wire 3 can only slide axially inside the wire slide 2, but cannot shake inside the wire slide 2.

[0035] The displacement measurement accuracy of the draw-wire sensor is greater than seven microns. The draw-wire displacement sensor can adopt a high-precision draw-wire displacement sensor disclosed in Chinese patent publication number CN202410715619.4.

[0036] The wire-drawing sensor is connected to a host computer, and the host computer has a built-in algorithm, which is used to calculate the elongation of the steel cable body according to the stretched length of the sensor wire, and then calculate the cable force of the steel cable body according to the elongation of the steel cable body.

[0037] Taking a cable curtain wall with a span of 20m as an example, the cross-sectional area is about 134mm 2 The stainless steel cable is used as the cable body 8. The elastic modulus of the stainless steel cable is about 130000MPa and the breaking force is about 190kN. Assuming that a total elastic elongation of 10 microns occurs and is obtained by the wire-drawing sensor, according to material mechanics and the above-mentioned measurement principle, it is deduced that the change in the cable force of the cable body 8 is about 8.7N. Within the entire measuring range, the breaking force of the cable is 190kN, and the measurement error is about 0.05‰. Of course, this measurement error is related to the span of the cable net curtain wall. The larger the span, the greater the overall elongation of the cable under the same tension, and the easier it is to be measured by the wire-drawing sensor. On the contrary, the measurement accuracy will be reduced, but This level of measurement accuracy has greatly exceeded the measurement accuracy of the "integrated sensor method". The measurement error of a general cable tension sensor is between 1% and 5%, or even higher. Therefore, the measurement accuracy of the present invention has far exceeded the engineering needs and is a high-resolution, high-sensitivity technical solution. The reason is that this overall deformation measurement method accumulates local micro-deformations for overall measurement, that is, only one measurement error is counted. In addition, with the development of electronic technology, the accuracy and stability of displacement sensors have been greatly improved. Therefore, the resolution and accuracy of this measurement technology are naturally very high, and are far higher than the measurement of a single cable tension.

[0038] It should be noted that this overall measurement method is more conducive to the evaluation of this cable curtain wall structure than the data obtained by the local cable force measurement of the "integrated sensor method". There are two reasons. First, the core issue of the safety performance of the cable curtain wall is the rotation ability of the glass. The strength of the cable component itself is often ranked after the glass shattering problem, because designers often leave a large margin for the cable component when designing the cable bearing capacity. In addition, the strength of the cable component generally does not change significantly with the increase of service life, so the safety of the cable component itself is very high. Glass is different. Glass is a brittle material. Once its rotation ability does not meet its own needs, it will shatter. The rotation ability of glass is determined by the overall stiffness of its supporting cable. In short, the safety performance of glass depends more on the overall stiffness of the cable component, and the local cable force measurement cannot fully cover the overall stiffness of the entire cable, or the expression is not accurate. Second, since the external load is transmitted to the frame component through the prestressed steel cable, the overall cable force is needed for the safety assessment of the cable curtain wall frame, rather than the local cable force of a certain cable. In short, the "integrated sensor method" is conducive to monitoring the safety of the cable components themselves, while the "separated sensor method" adopted by the present invention is more conducive to the evaluation of the overall safety performance of the cable curtain wall, and the effect is quite significant. Unlike other traditional monitoring schemes that require the monitoring system and the curtain wall system to be installed simultaneously, the monitoring system and the curtain wall system are independent of each other, and the monitoring system can be installed after the curtain wall system, and the installation process of the monitoring system hardly affects the use of the curtain wall system, which provides conditions for some existing curtain wall systems to add monitoring systems. The monitoring system has almost no effect on the appearance of the building. The size of the pull-wire displacement sensor storage box 1 does not exceed 100×100×100mm, which is much smaller than the outer dimensions of the anchor of the general steel cable, and is placed in the same area as the steel cable fixed end anchor 9 and the steel cable tensioning end anchor 6, and is generally blocked by the decorative surface; the wire diameter of the sensor wire 3 generally does not exceed 2mm, and it is located behind the glass joint with the steel cable, and will not be extra prominent to affect the use effect. The present invention measures the cable force of the entire cable, that is, the overall stiffness of the cable, so various evaluations are performed more accurately.

[0039] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example" or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, unless they are contradictory.

[0040] In the drawings of the embodiments disclosed in the present invention, only the structures related to the embodiments disclosed in the present invention are involved, and other structures can refer to the general design. In the absence of conflict, the same embodiment and different embodiments of the present invention can be combined with each other.

Claims

1. A cable force measurement and health monitoring system for a cable net curtain wall, characterized in that: include: The curtain wall lower frame-cable anchor point (5) is arranged on the lower frame of the cable net curtain wall, and the lower frame of the cable net curtain wall is fixedly connected to a steel cable tensioning end anchor (6) at the curtain wall lower frame-cable anchor point (5); The upper frame-cable anchor point (10) on the curtain wall is arranged on the upper frame of the cable net curtain wall, the upper frame of the cable net curtain wall is fixedly connected to a steel cable fixed end anchor (9) at the upper frame-cable anchor point (10) on the curtain wall, a steel cable body (8) is fixedly connected between the steel cable fixed end anchor (9) and the steel cable tensioning end anchor (6), and a glass claw (7) for fixing glass is fixedly connected to the steel cable body (8); A pull-wire displacement sensor storage box (1) is connected to the anchor (6) at the tensioning end of the steel cable, an outlet end of the pull-wire displacement sensor storage box (1) is connected to an extendable sensor pull wire (3), and a pull-wire displacement sensor for collecting the stretched length of the sensor pull wire (3) is arranged inside the pull-wire displacement sensor storage box (1); The sensor wire head fixed end (4) is arranged on the steel cable fixed end anchor (9), and the sensor wire (3) passes through the wire slide groove (2) on the glass gripper (7) and is fixedly connected to the sensor wire head fixed end (4).

2. The cable force measurement and health monitoring system of a cable net curtain wall according to claim 1, characterized in that: The sensor pull wire (3) is parallel to the steel cable body (8).

3. The cable force measurement and health monitoring system for a cable net curtain wall according to claim 1, characterized in that: The sensor pull wire (3) is fitted to the inner wall of the pull wire slide groove (2) and slides along the axis center line direction of the pull wire slide groove (2).

4. The cable force measurement and health monitoring system for a cable net curtain wall according to claim 1, characterized in that: The displacement measurement accuracy of the draw-wire sensor is greater than seven microns.

5. The cable force measurement and health monitoring system of a cable net curtain wall according to claim 4, characterized in that: The wire-drawing sensor is connected to a host computer, and the host computer has a built-in algorithm, which is used to calculate the elongation of the steel cable body according to the stretched length of the sensor wire, and then calculate the cable force of the steel cable body according to the elongation of the steel cable body.

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