Sensor Deployment Device and Method for Measuring Cavity Temperature of Variable Cross-Section Box Girder

Abstract

This invention proposes a sensor deployment device and method for measuring the cavity temperature of variable cross-section box girders, belonging to the technical field of variable cross-section box girder temperature measurement. It includes: a telescopic frame composed of horizontal and vertical bars, both of which employ a three-section nested structure comprising an inner and outer sleeve; a traction device located at the center of the telescopic frame, which drives the outer sleeve to extend and retract synchronously via multiple traction ropes and automatically locks; a temperature sensor clamp employing a U-shaped clamp seat and using built-in bearings to rotate the temperature sensor; and a positioning mechanism for locking and adsorption via butterfly bolts and a magnetic base. The sensor deployment device of this invention can closely conform to the box girder cross-section, adapting to the continuous and gradual changes in the box girder cross-section, and enabling rapid switching and temperature sensor deployment between different cross-sections of the box girder. This improves the efficiency of box girder temperature measurement, is less susceptible to displacement due to flue gas flow or structural vibration, and ensures the continuity and accuracy of temperature measurement data.

Description

Technical Field

[0001] This invention belongs to the field of temperature measurement technology for variable cross-section box girders, and particularly relates to a sensor deployment device and method for measuring the cavity temperature of variable cross-section box girders. Background Technology

[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.

[0003] Variable cross-section box girders, with their strong terrain adaptability and optimized structural stress, are widely used in urban overpasses, viaducts, and long-span bridge projects. Variable cross-section box girders are characterized by their varied cross-sectional dimensions, sealed cavities, and poor ventilation. The internal heating and cooling rates are significantly slower than the external rates, easily leading to internal and external temperature differences, temperature gradients along the cross-section, and temperature differences between the cavity and the top and bottom slabs of the box girder. Temperature stress is a major cause of cracking, deformation, and leakage in box girders; therefore, cavity temperature becomes a fundamental parameter for assessing the temperature field and calculating temperature stress in box girders. Without this data, temperature effect analysis would lack a basis.

[0004] However, current sensor deployment devices used for box girder temperature measurement are mostly rigid frame structures of fixed dimensions, and such devices typically have the following technical drawbacks: (1) Existing deployment devices are mostly designed with fixed dimensions, which makes them unsuitable for the characteristics of variable cross-section box girders with continuously changing top plate width, web height, and web inclination angle. Custom-made frames with special dimensions are required for different cross-sections, resulting in poor versatility. At the same time, in order to adapt to the variable cross-section characteristics of box girders, the frequent replacement or adjustment of temperature sensor deployment devices increases the time workers spend working at heights, indirectly increasing safety risks. In addition, existing deployment devices usually adopt a fixed design in terms of measuring point position and angle, which cannot be flexibly adjusted according to the testing plan. As a result, in order to achieve comprehensive temperature monitoring of the top plate, web, and bottom plate of the box girder, workers can only enter the narrow area inside the box girder to operate, further aggravating safety hazards.

[0005] (2) The existing deployment device is complicated to disassemble and assemble. When the box girder section is switched, it needs to be completely disassembled and reassembled and repositioned, which significantly prolongs the working time of the staff in dangerous environments such as high altitude and narrow space. At the same time, the deployment device is not stable enough and is easily displaced by environmental interference such as smoke flow and vibration. This not only affects the continuity and accuracy of temperature measurement data, but also requires the staff to enter the box girder again for adjustment after the displacement. Summary of the Invention

[0006] To overcome the shortcomings of the prior art, this invention provides a sensor deployment device and method for measuring the cavity temperature of a variable cross-section box girder. This device can closely fit the box girder cross-section, solving the problem that traditional temperature sensor deployment devices cannot adapt to the continuous and gradual changes in the box girder cross-section. It can quickly switch and deploy temperature sensors between different cross-sections of the box girder, avoiding the need for operators to re-enter the box girder to adjust the device, improving the efficiency of box girder temperature measurement, and reducing the operational risks for operators in high-altitude and confined environments. In addition, the device is not easily displaced by flue gas flow or structural vibration, thus ensuring the continuity and accuracy of the temperature measurement data.

[0007] To achieve the above objectives, one or more embodiments of the present invention provide the following technical solutions: The first aspect of the present invention provides a sensor deployment device for measuring the cavity temperature of a variable cross-section box girder.

[0008] A sensor deployment device for measuring the cavity temperature of a variable cross-section box girder includes: a telescopic frame, a traction device, a temperature sensor clamp, and a positioning mechanism. The retractable frame is a rectangular frame connected by horizontal and vertical bars, and both the horizontal and vertical bars adopt a three-section nested structure including an inner sleeve and an outer sleeve. The traction device is located at the center of the telescopic frame and is connected to the corresponding outer sleeve through multiple traction ropes in different directions. It is used to drive the outer sleeve to extend and retract synchronously relative to the inner sleeve and automatically lock after adjustment. The temperature sensor fixture adopts a U-shaped fixture base, and the rotation of the temperature sensor is achieved through the bearing built into the fixture base; The positioning mechanism includes a butterfly bolt for mechanically locking the telescopic frame by tightening the inner sleeve after telescopic adjustment, and a magnetic base for fixing the sensor deployment device to the surface of the box girder.

[0009] Furthermore, the three-section nested structure uses an outer sleeve as the middle structure, with an inner sleeve nested on each side of the outer sleeve; the horizontal and vertical bars designed with the three-section nested structure are connected by a rotatable joint with an angle scale.

[0010] Furthermore, a positioning hole is provided at preset intervals on the side wall of the outer sleeve; at the same time, a spring and an elastic buckle are provided at the end of the inner sleeve; the elastic buckle cooperates with the positioning hole for adjusting the length of the telescopic frame.

[0011] Furthermore, the traction device includes a built-in reel and a miniature drive motor for driving the reel to rotate.

[0012] Furthermore, the traction device is connected to the outer sleeves located above and below the telescopic frame via four obliquely outputting traction ropes, and to the outer sleeves located on the other two sides of the telescopic frame via another four obliquely outputting traction ropes; when the traction device rotates forward, all connected outer sleeves extend outward synchronously; when the traction device rotates in reverse, the inner sleeves retract inward synchronously, so as to realize the size adjustment of the telescopic frame.

[0013] Furthermore, during the traction process, the spring located at the end of the inner sleeve works in conjunction with the traction rope to automatically lock after adjustment.

[0014] Furthermore, the side wall of the outer sleeve is provided with a T-shaped groove, and a matching sliding block is provided in the groove; a U-shaped clamp seat is welded to the outside of the sliding block, and a temperature sensor clamp for laying temperature sensors is provided inside the U-shaped clamp seat.

[0015] Furthermore, the temperature sensor clamp adopts a semi-circular elastic clamp and has an anti-slip rubber pad attached inside.

[0016] Furthermore, the positioning mechanism also includes a press-type buckle, which is located on the top of the sliding block and is used to fix the sliding position when it slides into the toothed groove of the slide.

[0017] The second aspect of the present invention provides a sensor deployment method for measuring the cavity temperature of a variable cross-section box girder.

[0018] Sensor deployment methods for measuring the cavity temperature of variable cross-section box girders include: Move the sensor deployment device to the section of the box girder to be measured and align it with the telescopic frame; The telescopic frame size is adjusted by synchronously extending and retracting each outer sleeve through a traction device, and automatically locks after adjustment; positioning is completed by the elastic buckle at the end of the inner sleeve engaging with the positioning hole on the side wall of the outer sleeve. Tighten the wing bolts at the end of the outer sleeve to press the inner sleeve against the wall; loosen and rotate the rotatable joint to adjust the angle of the telescopic frame so that it fits against the inclination angle of the box girder web, and then tighten and fix it. Slide the temperature sensor clamp along the T-shaped groove to the target measuring point, and press the snap-on buckle to fix it; rotate the temperature sensor clamp to the preset position through the bearing, and put in the temperature sensor; The sensor deployment device is attached to the box girder using a magnetic base, and temperature measurement is performed. After the current section monitoring is completed, the positioning mechanisms are released, and the traction device is activated to retract the telescopic frame. Then, the above steps are repeated to complete the deployment of temperature sensors on the new section of the box girder.

[0019] The above one or more technical solutions have the following beneficial effects: This invention employs a three-section nested telescopic frame consisting of an inner and outer sleeve, which, in conjunction with a traction device, enables multi-directional synchronous telescopic adjustment. A rotatable joint with angular graduations adapts to different web inclination angles, allowing a single temperature sensor deployment device to measure the temperature of variable cross-section box girders with varying top plate widths, web heights, and web inclination angles. This eliminates the need for custom-sized frames to accommodate the variable cross-section characteristics of the box girder, significantly improving the versatility of the sensor deployment device. Simultaneously, the temperature sensor clamp utilizes a T-shaped sliding groove to flexibly adjust the measuring point position, and the bearings built into the U-shaped clamp seat allow for free rotation of the temperature sensor angle. This enables operators to deploy and measure the temperature of the box girder cavity from the outside without entering the narrow interior area, significantly reducing the safety risks associated with working at heights and in confined spaces.

[0020] This invention utilizes a traction device to drive the synchronous extension and retraction of the outer casing and its automatic locking function, combined with a butterfly bolt for rapid mechanical tightening. This enables rapid switching and positioning between different sections of the box girder, allowing for temperature measurement within the cavities of different box girder sections without the need for complete disassembly and reassembly. This significantly reduces the working time for operators in high-altitude and confined environments. Simultaneously, a magnetic base securely attaches the sensor deployment device to the box girder surface, and a press-type buckle precisely positions the sliding block. This provides the sensor deployment device with excellent anti-interference capabilities during temperature measurement, preventing displacement due to flue gas flow or vibration. This avoids the need for personnel to re-enter the box girder for device adjustments, ensuring the continuity and accuracy of temperature data and improving the efficiency of box girder temperature measurement.

[0021] Advantages of additional aspects of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0022] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0023] Figure 1 This is a structural diagram of the sensor deployment device for measuring the cavity temperature of a variable cross-section box girder in Embodiment 1 of the present invention.

[0024] Figure 2 This is a flowchart of the sensor deployment method for measuring the cavity temperature of a variable cross-section box girder in Embodiment 2 of the present invention.

[0025] In the diagram: 1. Inner sleeve; 2. Outer sleeve; 3. Temperature sensor clamp; 4. Rotatable joint; 5. Crossbar; 6. Wing bolt; 7. Magnetic base; 8. Traction device; 9. Traction rope. Detailed Implementation

[0026] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0027] It should be noted that the terminology used herein is for the purpose of describing particular implementations only and is not intended to limit the exemplary implementations of the present invention.

[0028] Where there is no conflict, the embodiments and features in the embodiments of the present invention can be combined with each other.

[0029] Example 1 This embodiment discloses a sensor deployment device for measuring the cavity temperature of a variable cross-section box girder.

[0030] A sensor deployment device for measuring the cavity temperature of a variable cross-section box girder includes: a telescopic frame, a traction device, a temperature sensor clamp, and a positioning mechanism. The retractable frame is a rectangular frame connected by horizontal and vertical bars, and both the horizontal and vertical bars adopt a three-section nested structure including an inner sleeve and an outer sleeve. The traction device is located at the center of the telescopic frame and is connected to the corresponding outer sleeve through multiple traction ropes in different directions. It is used to drive the outer sleeve to extend and retract synchronously relative to the inner sleeve and automatically lock after adjustment. The temperature sensor fixture adopts a U-shaped fixture base, and the rotation of the temperature sensor is achieved through the bearing built into the fixture base; The positioning mechanism includes a butterfly bolt for mechanically locking the telescopic frame by tightening the inner sleeve after telescopic adjustment, and a magnetic base for fixing the sensor deployment device to the surface of the box girder.

[0031] Based on the above-described structural design, this invention enables flexible adaptation to variable cross-section box girders of different sizes and inclination angles, while simultaneously improving stability and personnel safety during temperature measurement. To facilitate understanding of the technical solution of this invention, the specific implementation methods are further explained and described below.

[0032] like Figure 1 As shown, the sensor deployment device for measuring the cavity temperature of a variable cross-section box girder includes: 1) Scalable frame.

[0033] The telescopic frame is a rectangular frame composed of horizontal and vertical bars. Both horizontal and vertical bars are three-section aluminum alloy sleeves with inner and outer nesting, meaning the middle section is an outer sleeve, and each side has an inner sleeve. This three-section, bidirectional telescopic structure significantly increases the telescopic stroke, enabling continuous adjustment of the frame size over a wide range to accommodate the gradually changing dimensions of the box girder. Furthermore, it ensures symmetrical stress distribution, smooth telescopic movement, and reduced skewing, thereby improving overall structural stability and positioning accuracy. Simultaneously, its compact size after retraction facilitates transportation and storage, greatly enhancing the device's versatility and ease of use. The horizontal and vertical bars are connected by rotatable joints with angular graduations (0-90°) to better adapt to the box girder's inclination angle.

[0034] The outer sleeve has a positioning hole every 2cm on its side wall, and the inner sleeve end is equipped with a spring and an elastic buckle. By cooperating with the positioning holes, the length can be adjusted from 50cm to 200cm horizontally and from 30cm to 150cm vertically. The elastic buckle is a part that uses the elastic deformation properties of materials to achieve connection or fixation. When an external force is applied, the buckle deforms and can engage or disengage from the mating part, so that it can remain locked in the locked state by the elastic restoring force after the external force is removed.

[0035] 2) Automatically rotating traction device.

[0036] The automatic size adjustment of the telescopic frame can be achieved through the interaction of the aforementioned springs and the traction ropes of the central traction device (i.e., the traction unit). The traction unit has a built-in reel and a miniature drive motor, located at the center of the telescopic frame. The traction unit outputs eight traction ropes in eight different radial directions, each independently connected to the ends of eight outer sleeves corresponding to the horizontal and vertical bars. Specifically, four traction ropes are connected to the left and right outer sleeves of the upper horizontal bar, the left and right outer sleeves of the lower horizontal bar, and the right outer sleeve of the lower horizontal bar, respectively; the other four traction ropes are connected to the upper and lower outer sleeves of the left and right vertical bars, respectively. When the traction unit rotates forward, the eight traction ropes are released synchronously, coordinating with the inner sleeve springs to drive all the outer sleeves to extend outwards synchronously, expanding the overall frame. When the traction unit rotates in reverse, the eight traction ropes retract synchronously, driving all the outer sleeves to retract inwards synchronously, shrinking the overall frame. Through independent traction in eight radial directions from the center, the frame size can be adjusted automatically, uniformly, synchronously, and without deviation, and automatically locked after adjustment.

[0037] Based on this, automatic synchronous adjustment can be achieved: when the traction device rotates forward, all eight outer sleeves will extend outward simultaneously, and the frame will automatically enlarge; when the traction device rotates in reverse, all inner sleeves will retract inward simultaneously, and the frame will automatically shrink. At the same time, it can also achieve a self-locking function: the traction rope of the traction device and the spring of the inner sleeve cooperate with each other, and automatically lock after adjustment, without rebounding or retracting, without the need for manual alignment.

[0038] 3) A sliding and rotating temperature sensor clamp.

[0039] Temperature sensor selection: Priority recommendation (generally applicable to box girder cavity and structural temperature measurement, fully compatible with this fixture), for example: a) PT100 Platinum Resistance Temperature Sensor (Preferred for High-Precision Static Temperature Measurement) Temperature Range: -50℃ to +200℃, suitable for the natural ambient temperature of bridges (year-round ambient temperature range). Features: High measurement accuracy (Class A accuracy up to ±0.15℃), extremely strong stability, vibration resistant, suitable for long-term online monitoring. Adaptation and Modification: Uses Φ2~Φ3mm thin rod probes, which can be directly installed into elastic clips; the cable is temperature-resistant and wear-resistant, suitable for the sealed environment of box girders and slight vibration environments. Applications: Long-term service temperature monitoring of bridges, routine temperature gradient observation, and projects with high data accuracy requirements.

[0040] b) Type K thermocouple (full coverage scenario), temperature measurement range: -200℃ to +1200℃, meeting all working conditions such as normal environment, solar heating, fire, and high-temperature testing. Features: small size, slender probe adapted to U-shaped elastic clamp; good linearity, convenient wiring, multi-channel centralized data acquisition, compatible with bridge automated monitoring systems. Applications: conventional box girder temperature gradient monitoring, solar temperature difference testing, high-temperature simulation testing; this is also the preferred model in this embodiment.

[0041] The temperature sensor fixture uses a U-shaped fixture base, and the temperature sensor is rotated by a bearing built into the fixture base. Specifically, T-shaped grooves are formed on the side walls of the outer sleeves of the horizontal and vertical bars, and matching sliding blocks are installed in the grooves. A U-shaped fixture base is welded to the outside of the sliding blocks. The fixture base has a built-in bearing and a temperature sensor fixture for placing the temperature sensor. The temperature sensor fixture can rotate 360° through the bearing. The temperature sensor fixture uses a semi-circular arc elastic clamp with an anti-slip rubber pad attached to the inside, and the temperature sensor is fixed by tightening with M6 bolts.

[0042] The clamp uses a semi-circular elastic clip with an anti-slip rubber pad attached to the inside, and is secured to the K-type temperature sensor by tightening with M6 bolts.

[0043] The U-shaped clamp base consists of a horizontal base and two arms perpendicular to the horizontal base, forming a U-shaped groove. This shape allows it to easily wrap around and accommodate the object being clamped; the arms provide lateral clamping force, while the horizontal base provides support and fixation. As an optional implementation, screw holes, air intake channels, and other structures can be incorporated inside the U-shaped clamp base to meet different usage requirements.

[0044] 4) A positioning mechanism that can be quickly locked.

[0045] The positioning mechanism includes a wing bolt, a push-button latch, and a magnetic base. Specifically, the wing bolt is located at the end of the outer sleeve and is tightened after adjustment to achieve telescopic locking by pressing against the inner sleeve; the push-button latch is located on the top of the sliding block and is used to fix the sliding position when it slides into the toothed groove of the slide; the magnetic base is added to the bottom of the four corner vertical bars of the telescopic frame and has anti-slip rubber pads to facilitate the adsorption and fixation of steel box girders. Additionally, for concrete box girders, expansion bolts can be used in conjunction.

[0046] Example 2 This embodiment discloses a sensor deployment method for measuring the cavity temperature of a variable cross-section box girder.

[0047] like Figure 2 As shown, the sensor deployment method for measuring the cavity temperature of a variable cross-section box girder includes: Move the sensor deployment device to the section of the box girder to be measured and align it with the telescopic frame; The telescopic frame size is adjusted by synchronously extending and retracting each outer sleeve through a traction device, and automatically locks after adjustment; positioning is completed by the elastic buckle at the end of the inner sleeve engaging with the positioning hole on the side wall of the outer sleeve. Tighten the wing bolts at the end of the outer sleeve to press the inner sleeve against the wall; loosen and rotate the rotatable joint to adjust the angle of the telescopic frame so that it fits against the inclination angle of the box girder web, and then tighten and fix it. Slide the temperature sensor clamp along the T-shaped groove to the target measuring point, and press the snap-on buckle to fix it; rotate the temperature sensor clamp to the preset position through the bearing, and put in the temperature sensor; The sensor deployment device is attached to the box girder using a magnetic base, and temperature measurement is performed. After the current section monitoring is completed, the positioning mechanisms are released, and the traction device is activated to retract the telescopic frame. Then, the above steps are repeated to complete the deployment of temperature sensors on the new section of the box girder.

[0048] Furthermore, the sensor deployment method for measuring the cavity temperature of a variable cross-section box girder can be implemented through the following steps: Step 1: The monitoring device is in place.

[0049] The sensor deployment device was moved to the section of the box girder where temperature monitoring was to be performed, and the telescopic frame was aligned with the box girder section and placed stably to ensure complete coverage of the monitoring area.

[0050] Step 2: Frame size is automatically adjusted.

[0051] The central automatic rotation traction device (i.e., traction unit) is activated, which drives the reel to wind and unwind the traction rope via a micro motor, causing the inner sleeves of the horizontal and vertical bars to extend and retract synchronously. During forward rotation: the traction rope pulls the inner sleeve out, and the frame size expands; During reversal: the traction rope retracts, the inner sleeve retracts under the action of the spring, and the frame size shrinks; after adjustment, it automatically locks, without rebounding or shifting, quickly matching the width and height of the box girder section.

[0052] When measuring different cross sections, the central automatic rotating traction device pulls the traction rope made of steel strand used for connection, which compresses or releases the spring inside the sleeve, thereby realizing the size change of the frame without disassembly and reassembly.

[0053] Step 3: Precisely determine the dimensions.

[0054] Gently push and pull the inner sleeve to allow the end elastic buckle to engage with the positioning hole of the outer sleeve, thus completing the precise positioning of the frame size and meeting the requirements for monitoring section adaptation.

[0055] Step 4: Lock the telescopic mechanism.

[0056] Tighten the wing bolts at the end of the outer sleeve to press the inner sleeve into place, achieving mechanical locking and ensuring that the frame remains dimensionally stable and does not loosen during long-term monitoring.

[0057] Step 5: Adapt the cross-section inclination angle.

[0058] If the box girder has an inclined web section, loosen the rotatable joint with angle markings, adjust the angle of the telescopic frame to fit the box girder section, and tighten the rotatable joint bolts to fix the angle and ensure accurate monitoring angle.

[0059] Step 6: Locate the monitoring point.

[0060] Slide the temperature sensor clamp along the T-shaped groove of the outer sleeve of the horizontal and vertical bars, and adjust the horizontal and vertical spacing of the measuring points according to the temperature monitoring scheme; after reaching the set position, press the push-button buckle to complete the clamp fixation.

[0061] Step 7: Monitor angle adjustment.

[0062] The temperature sensor clamp is rotated 360° by the bearing, and the angle of the elastic clamp is adjusted to make the clamp perpendicular and fit the measured surface of the box girder, ensuring reliable contact of the temperature sensor.

[0063] Step 8: Install and fix the temperature sensor.

[0064] Place the temperature sensor into the semi-circular elastic clip to ensure that the probe is in close contact with the surface of the box girder; tighten the M6 ​​bolts and use the anti-slip rubber pads to clamp and fix it to prevent loosening from affecting the monitoring accuracy.

[0065] Step 9: Secure the entire device.

[0066] Choose the fixing method based on the box girder material: Steel box girder: directly attached and fixed using a magnetic base; Concrete box girder: anchored with expansion bolts through pre-drilled holes in the base; ensuring that the device does not shift or shake during long-term monitoring.

[0067] Step 10: Temperature monitoring and cross-section switching.

[0068] After the device is installed, connect it to the acquisition equipment to monitor the temperature of the box girder structure. When it is necessary to switch the monitoring section, loosen the locking mechanism, start the traction device to retract the frame, and repeat steps 1-9 to quickly complete the deployment of the temperature sensor without the need for overall disassembly.

[0069] Furthermore, to facilitate understanding of the implementation method of the present invention, this embodiment will be further described in more detail using a variable cross-section steel box girder test section of a cross-river bridge.

[0070] The test section of the cross-river bridge's variable cross-section steel box girder is a single-box, single-cell structure, employing a gradually changing cross-section design to adapt to the bridge's stress requirements. The parameters of each section within the test area are as follows: web inclination angle gradually changes from 25° to 55°, top plate width gradually changes from 90cm to 160cm, and web height gradually changes from 60cm to 130cm. According to the temperature field monitoring requirements of the heating test, 10 temperature sensor measuring points need to be arranged at each test section (4 on the top plate and 3 on each of the two web plates). The measuring points need to be evenly distributed and perpendicularly attached to the measured surface of the box girder. The sensor deployment device for measuring the cavity temperature of the variable cross-section box girder, as described in this invention, is implemented as follows: Step 1: Device Inspection and Preparation Before the test, a comprehensive inspection of the device is conducted to confirm that the inner sleeve 1 and outer sleeve 2 of the main telescopic frame extend and retract smoothly without any jamming. The condition of the micro motor, reel, and traction rope 9 of the traction device 8 is checked to ensure reliable traction synchronization and self-locking function. The sliding flexibility and 360° rotation smoothness of the sliding and rotating temperature sensor clamp 3 are tested to confirm that the elastic clamp is not deformed and the anti-slip rubber pad is intact. The performance of the butterfly bolt 6, press-type buckle, and magnetic base 7 of the quick-locking positioning mechanism is checked to ensure that the magnetic attraction is firm and the locking is effective. Subsequently, the magnetic base 7 is installed at the bottom of the four corner vertical bars of the frame, and the anti-slip rubber pad is affixed and wiped clean. Ten sets of temperature sensors (2.5mm diameter K-type thermocouples) are prepared, and the temperature sensor probes are verified to be intact. The temperature acquisition equipment is connected in advance and tested to ensure normal operation.

[0071] Step 2: Automatic Adjustment and Precise Positioning of Frame Dimensions. Select the first test section (top plate width 110cm, web plate height 90cm), move the entire device below this section, and adjust the device position so that the horizontal bars 5 and vertical bars of the main telescopic frame are aligned with the box girder test section, ensuring that the frame covers the entire monitoring area. Start the traction device 8, control the motor to rotate forward, drive the reel to release the traction rope 9, pulling the inner sleeves 1 of the horizontal bars 5 and vertical bars outward synchronously, and observe the changes in frame dimensions in real time; when the horizontal bar 5 is stretched to 110cm and the vertical bar is stretched to 90cm, turn off the traction device 8. At this time, the device automatically locks using the cooperation of the traction rope 9 and the spring of the inner sleeve 1, and the frame has no rebound or retraction. Then gently push the inner sleeves 1 of the horizontal bars 5 and vertical bars so that the elastic buckle at the end of the inner sleeve 1 accurately engages with the corresponding positioning hole of the outer sleeve 2 (the outer sleeve has a positioning hole every 2cm, corresponding to the 110cm and 90cm positions), completing the precise positioning of the frame dimensions and ensuring that the dimensional error is ≤1cm.

[0072] Step 3: Adapting the inclination angle of the box girder section. The inclination angle of the web of the first test section is 40°. Loosen the locking bolt of the rotatable joint 4 with angle scale (0-90°) at the connection between the horizontal bar 5 and the vertical bar. Slowly rotate the vertical bar to make the frame vertical bar fit with the web of the box girder. At the same time, refer to the angle scale at the joint. Stop rotating when it reaches 40°. Tighten the locking bolt of the rotatable joint. Use a right angle ruler and inclinometer to check and ensure that the frame fits tightly with the web of the box girder. The inclination angle error is ≤0.3°. Avoid the displacement of the measuring point layout due to the inclination angle deviation, which will affect the temperature measurement accuracy.

[0073] Step 4: Monitoring Point Positioning and Angle Adjustment. According to the test monitoring plan, the 10 measuring points are arranged as follows: 4 measuring points on the top plate are evenly distributed along the horizontal bar, with a spacing of 27.5cm; 3 measuring points on each of the two web plates are evenly distributed along the vertical bar, with a spacing of 30cm. Slowly slide the 4 temperature sensor clamps 3 along the T-shaped grooves on the outer sleeve of the horizontal bar. Each time the clamp reaches the set spacing position, press the push-type buckle on the top of the sliding block to make the buckle engage with the groove teeth, completing the lateral positioning of the clamps. Similarly, slide 3 clamps along the T-shaped grooves on each of the two vertical bar outer sleeves and fix them according to the spacing requirements to ensure that all clamps are accurately positioned and firmly fixed. Then, rotate each temperature sensor clamp 360° through the bearings built into the clamp seat, and adjust the angle of the semi-circular elastic clamp to make the clamp perpendicular to the measured surface (top plate and web plate) of the box girder. Use visual observation and a ruler to confirm that the probe contact direction is accurate, ensuring the reliability of subsequent temperature acquisition.

[0074] Step 5: Installation and overall fixation of the temperature sensors (2.5mm diameter K-type thermocouples). Place the 10 temperature sensors into the semi-circular elastic clamps of their respective fixtures. Adjust the position of the temperature sensor probes to ensure tight contact between the probes and the steel surface of the box girder, without gaps or looseness. Then tighten the M6 ​​bolts, using the elasticity of the clamps and the friction of the inner anti-slip rubber pads to firmly fix the temperature sensors, preventing probe displacement due to vibration or high temperature during the test. After fixation, check the contact of all temperature sensor probes. Once confirmed, use the magnetic bases at the four corners of the frame to attach the entire device to the surface of the steel box girder. Gently push each part of the frame to confirm that the device does not shift or shake, ensuring stability during long-term monitoring. Finally, connect the temperature sensors to the temperature acquisition equipment, debug the acquisition equipment, and ensure normal data transmission.

[0075] Step 6: Rapid switching of test sections. After completing the first section setup, proceed to the next test section (top plate width 150cm, web plate height 120cm, inclination angle 55°). First, loosen the wing bolts at the ends of the horizontal and vertical rod outer sleeves, start the traction device, control the motor to rotate forward, and pull the inner sleeve of the horizontal rod to extend to 150cm and the inner sleeve of the vertical rod to extend to 120cm. After turning off the traction device, gently push the inner sleeve to make the elastic buckle engage with the corresponding positioning hole, and retighten the wing bolts to lock it in place. Then, loosen the locking bolt of the rotatable joint, adjust it to 55° according to the angle scale, tighten the bolts, and check the inclination angle. Slide each temperature sensor fixture along the slide, adjust the measuring point spacing (37.5cm for the top plate and 40cm for the web plate), press the buckle to fix the fixture, rotate the fixture to adjust the angle, and repeat the temperature sensor installation, device fixing, and data acquisition equipment debugging steps. The entire section switching process takes about 3.5 minutes, without the need for complete disassembly of the device, which greatly improves the setup efficiency.

[0076] Step 7: Temperature Heating Test Monitoring and Device Performance Verification. The temperature heating test was initiated, and heating was carried out according to the preset test conditions. During the process, temperature data at each measuring point was monitored in real time using temperature acquisition equipment, and the device status was observed in real time using a high-definition camera. Throughout the test, the device remained stable and secure, the temperature sensor clamps were firmly fixed with no change in angle, and the temperature sensor probes remained in close contact with the box girder surface. After the test, the collected temperature data was analyzed. The results showed that the temperature curves at each measuring point were continuous and stable, with no abnormal fluctuations. The measurement error was controlled within ±0.3℃, fully meeting the accuracy requirements for temperature field monitoring in fire tests of variable cross-section steel box girders.

[0077] During the test, the device can quickly adapt to different size and tilt angle requirements for all gradient cross-section arrangements. It is easy to operate and does not require the test personnel to repeatedly adjust and tie it at close range, which greatly reduces the operation risk in high temperature environment and improves test efficiency. At the same time, the device can be reused. After the test, the locking mechanisms can be loosened and the traction device can be activated to retract the telescopic frame to the minimum size, which is convenient for handling and storage and reduces test costs.

[0078] Based on the above methods and structured design, compared with the prior art, the present invention can achieve the following technical breakthroughs: 1) Cross-sectional adaptability.

[0079] Traditional sensor deployment devices use fixed-size rigid frames, requiring custom-made frames for different cross-sections, resulting in high operating costs and cumbersome replacement processes. This invention employs a three-section nested telescopic sleeve paired with a 0–90° graduated rotatable joint. The lateral dimension is continuously adjustable from 50–200cm, and the vertical dimension from 30–150cm, adapting to web structures with varying inclination angles. A single sensor deployment device can meet the needs of various variable cross-section box girders, eliminating the need for custom-made accessories. It precisely conforms to the gradual changes in the box girder cross-section, completely solving the problem of traditional rigid frames being unable to adapt to continuous changes in top plate width, web height, and web inclination angle, significantly improving the device's versatility.

[0080] 2) Adjusting the driving force and construction efficiency.

[0081] Traditional deployment devices rely on manual stretching, alignment, and assembly, which is time-consuming and labor-intensive. This invention is equipped with a central traction device that drives eight sets of sleeves to extend and retract synchronously, enabling one-click scaling of the retractable frame. After adjustment, it automatically locks, eliminating the need for manual adjustment. When switching the measurement section of the box girder, simply loosening the positioning locking structure and fine-tuning the dimensions and inclination angle completes the temperature sensor deployment. The entire process requires no complete disassembly and reassembly, effectively reducing the time workers spend at heights and in confined spaces.

[0082] 3) Measurement point layout and temperature measurement accuracy.

[0083] Traditional temperature measurement devices have fixed measurement point positions and installation angles, making flexible adjustments impossible based on the testing plan. This invention utilizes a T-shaped sliding groove to freely adjust the measurement point position, and the built-in bearing in the clamp allows for 360° rotation of the temperature sensor, ensuring the probe is perpendicularly attached to the measured surface, resulting in stable temperature data and minimal error. The device employs 2cm spacing positioning holes, elastic buckles, and butterfly bolts for multiple positioning and locking mechanisms, achieving higher precision in dimensional and tilt angle control. The measurement point layout standardization and temperature measurement accuracy are superior to traditional devices.

[0084] 4) Stability and anti-interference aspects.

[0085] Traditional rigid frames have weak resistance to disturbances and are prone to displacement due to flue gas flow and structural vibrations, resulting in distorted temperature measurement data and requiring personnel to re-enter the box girder for adjustments. This invention, however, incorporates multiple fixing structures including wing bolts, push-button clips, magnetic bases, and expansion bolts. The overall structure is stable, with strong anti-interference capabilities, and is not easily loosened or slipped during testing. This eliminates the need for secondary adjustments, ensuring continuous temperature measurement.

[0086] 5) Safety in operation.

[0087] Traditional temperature measurement methods require workers to enter the narrow space inside the box girder for installation, which poses safety hazards such as falls, collisions, and high-temperature injuries due to working at heights and in confined spaces. This invention allows for the installation and adjustment of temperature sensors outside the box girder, eliminating the need for personnel to enter the cavity, reducing high-risk operations, and fundamentally lowering operational safety risks.

[0088] While the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of the present invention are still within the scope of protection of the present invention.

Claims

1. A sensor deployment device for measuring the cavity temperature of a variable cross-section box girder, characterized in that, include: Retractable frame, traction device, temperature sensor clamp, and positioning mechanism; The retractable frame is a rectangular frame connected by horizontal and vertical bars. Both the horizontal and vertical bars employ a three-section nested structure, including an inner sleeve and an outer sleeve. In this three-section nested structure, the outer sleeve serves as the central structure, with an inner sleeve nested on each side. The horizontal and vertical bars, designed with this three-section nested structure, are connected via rotatable joints with angular graduations. A T-shaped groove is formed on the side wall of the outer sleeve, and a matching sliding block is provided within the groove. A U-shaped clamp seat is welded to the outside of the sliding block, and a temperature sensor clamp for mounting a temperature sensor is provided inside the U-shaped clamp seat. The traction device is located at the center of the telescopic frame and is connected to the corresponding outer sleeve through multiple traction ropes in different directions. It is used to drive the outer sleeve to extend and retract synchronously relative to the inner sleeve and automatically lock after adjustment. The temperature sensor fixture adopts a U-shaped fixture base, and the rotation of the temperature sensor is achieved through the bearing built into the fixture base; The positioning mechanism includes a butterfly bolt for mechanically locking the telescopic frame by tightening the inner sleeve after telescopic adjustment, and a magnetic base for fixing the sensor deployment device to the surface of the box girder.

2. The sensor deployment device for measuring the cavity temperature of a variable cross-section box girder as described in claim 1, characterized in that, A positioning hole is provided at preset intervals on the side wall of the outer sleeve; at the same time, a spring and an elastic buckle are provided at the end of the inner sleeve; the elastic buckle cooperates with the positioning hole to adjust the length of the telescopic frame.

3. The sensor deployment device for measuring the cavity temperature of a variable cross-section box girder as described in claim 1, characterized in that, The traction device includes a built-in reel and a miniature drive motor for driving the reel to rotate.

4. The sensor deployment device for measuring the cavity temperature of a variable cross-section box girder as described in claim 3, characterized in that, The traction device is connected to the outer sleeves located above and below the telescopic frame via four diagonally outputting traction ropes, and to the outer sleeves located on the other two sides of the telescopic frame via another four diagonally outputting traction ropes. When the traction device rotates forward, all connected outer sleeves extend outward synchronously. When the traction device rotates in reverse, the inner sleeves retract inward synchronously, thereby realizing the size adjustment of the telescopic frame.

5. The sensor deployment device for measuring the cavity temperature of a variable cross-section box girder as described in claim 4, characterized in that, During traction, the spring located at the end of the inner sleeve works in conjunction with the traction rope to automatically lock after adjustment.

6. The sensor deployment device for measuring the cavity temperature of a variable cross-section box girder as described in claim 1, characterized in that, The temperature sensor clamp uses a semi-circular elastic clip and has an anti-slip rubber pad attached inside.

7. The sensor deployment device for measuring the cavity temperature of a variable cross-section box girder as described in claim 1, characterized in that, The positioning mechanism further includes a press-type buckle, which is located on the top of the sliding block and is used to fix the sliding position when it slides into the toothed groove of the slide.

8. A sensor deployment method for measuring the cavity temperature of a variable cross-section box girder, using the sensor deployment device as described in any one of claims 1-7, characterized in that, include: Move the sensor deployment device to the section of the box girder to be measured and align it with the telescopic frame; The telescopic frame size is adjusted by synchronously extending and retracting each outer sleeve through a traction device, and automatically locks after adjustment; positioning is completed by the elastic buckle at the end of the inner sleeve engaging with the positioning hole on the side wall of the outer sleeve. Tighten the wing bolts at the end of the outer sleeve to press the inner sleeve against the wall; loosen and rotate the rotatable joint to adjust the angle of the telescopic frame so that it fits against the inclination angle of the box girder web, and then tighten and fix it. Slide the temperature sensor clamp along the T-shaped groove to the target measuring point, and press the snap-on buckle to fix it; rotate the temperature sensor clamp to the preset position through the bearing, and put in the temperature sensor; The sensor deployment device is attached to the box girder using a magnetic base, and temperature measurement is performed. After the current section monitoring is completed, the positioning mechanisms are released, and the traction device is activated to retract the telescopic frame. Then, the above steps are repeated to complete the deployment of temperature sensors on the new section of the box girder.

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