Straddle type monorail track beam prestress self-compensation structure and control method

Abstract

The invention relates to the technical field of rail transit, and discloses a straddle type monorail track beam prestress self-compensation structure and a control method. The prestressed steel beams are longitudinally arranged on a web plate and a bottom plate of the track beam; the pull rod bundle comprises a plurality of pull rods arranged in the center of the track beam bottom plate, and the line type of the pull rods is the same as that of the prestressed steel bundle; the anchorage devices are installed at the two ends of the track beam and matched with the prestress steel beams and the pull rod beams respectively; the heating wire is wound on the surface of the pull rod bundle; the insulating layer is mounted on the outer side of the heating wire; the plurality of fiber grating sensors are respectively embedded in the midspan position and the quarter-span position at the two ends of the track beam and are used for capturing the prestress change of the track beam; and the PLC is connected with the plurality of fiber grating sensors and the heating wire through cables. Through automatic compensation of the SMA pull rods, the prestress loss rate is effectively controlled, and the rigidity stability of the track beam body is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of rail transit, in particular to a straddle-type monorail track beam prestress self-compensation structure and control method. BACKGROUND

[0002] In the straddle-type monorail rail transit system, the track beam is the core bearing structure for vehicle operation, and is usually designed as a prestressed concrete (PC) box beam. The stiffness stability of the track beam directly determines the safety and comfort of the vehicle operation. However, in the long-term operation process, the PC track beam generally faces prestress loss, which leads to large deflection of the track beam and uneven vehicle operation, becoming a major problem in vehicle-bridge coupling. The main causes include the following aspects: within 5 years of operation, the prestress loss rate caused by concrete creep can reach 5%-8%, and the shrinkage deformation further aggravates the deflection of the beam body; the traditional prestressed steel strand has stress relaxation under long-term load, and the annual loss rate is about 1%-1.5%; environmental factors such as humidity and salt cause corrosion of the steel strand, weaken the effective prestress, and in severe cases, cause anchor failure.

[0003] In view of the above problems, the existing solutions have obvious defects: manual tensioning needs to stop operation and has a long operation time, which affects the operation efficiency; the tensioning accuracy is controlled by relying on manual experience, the error is large, and multiple tensioning can easily cause cracking of the concrete near the anchor; the cost of replacing the track beam is high, the construction period is long, and the traffic interruption is large; passive reinforcement such as sticking FRP plate can only improve the local stiffness and cannot solve the fundamental problem of prestress loss, and long-term interface peeling is easy to occur.

[0004] Therefore, in order to solve this problem in the straddle-type monorail vehicle-bridge coupling, it is urgent to develop a track beam structure that can realize real-time monitoring and automatic compensation of prestress, does not affect operation, and has controllable cost, to inhibit stiffness degradation from the source.

[0005] At present, no effective solution has been proposed for the problems in the related art. SUMMARY

[0006] In view of the problems in the related art, the present application proposes a straddle-type monorail track beam prestress self-compensation structure and control method to overcome the above technical problems existing in the prior art.

[0007] Therefore, the specific technical solutions adopted by the present application are as follows: In a first aspect, the present invention provides a straddle-type monorail prestressed self-compensating structure, comprising: a track beam; a plurality of prestressed steel strands arranged longitudinally in the web and bottom plate of the track beam; a tie rod bundle, including a plurality of tie rods arranged at the center of the bottom plate of the track beam, wherein the shape of the tie rods is the same as that of the prestressed steel strands; a plurality of anchors installed at both ends of the track beam and respectively cooperating with the plurality of prestressed steel strands and the tie rod bundle; heating wires wound around the surface of the tie rod bundles; an insulating layer installed on the outside of the heating wires; a plurality of fiber optic grating sensors respectively embedded in the mid-span and the quarter-span positions at both ends of the track beam for capturing changes in the prestress of the track beam; and a PLC controller, all of which are connected to the plurality of fiber optic grating sensors and the heating wires via cables.

[0008] Furthermore, to ensure the load-bearing capacity of the track beam, the track beam has pre-reserved channels extending longitudinally inside to cooperate with the tie rod bundle; the track beam adopts a precast prestressed concrete PC box structure to be suitable for straddle-type monorail vehicles.

[0009] Furthermore, to ensure the load-bearing capacity of the track beam, the prestressed steel strands are made of several 1860MPa high-strength, low-relaxation steel strands.

[0010] Furthermore, to improve the stiffness and stability of the track beam, the surface of the tie rod bundle is coated with polytetrafluoroethylene to enhance corrosion resistance and lubrication, thereby reducing shrinkage resistance. The tie rod bundle is interspersed inside the reserved channels in the track beam, and the reserved channels are filled with an epoxy resin isolation layer that matches the tie rod bundle to isolate the concrete from direct contact with the tie rod. The tie rod is made of SMA shape memory alloy.

[0011] Furthermore, to ensure the sealing of the ducts, the outer side of the anchorage is coated with waterproof paint; the ends of the prestressed steel strands and tie rods are fixed with self-anchoring anchorages; the anchorages are connected to the end plates of the track beams with M20 high-strength bolts, and the gap between the anchorages and the track beams is filled with rubber expansion plugs and C60 micro-expansion concrete is poured to ensure that the ducts are filled tightly.

[0012] Furthermore, to avoid high-temperature damage to the concrete, the prestressed steel strands and tie rods are designed to be arranged in parallel to precisely set the phase transition temperature to 60-80℃.

[0013] Furthermore, to effectively control the prestress loss rate, the heating wire is made of nickel-chromium material. The insulation layer is made of high-temperature resistant material.

[0014] Furthermore, to ensure the uniformity of the fiber Bragg grating sensor's detection of the track beam, the fiber Bragg grating sensor is pre-embedded at three points in the middle and quarter spans of track beam 1, and the fiber Bragg grating sensor is buried at a depth of 30mm to avoid areas with dense reinforcement.

[0015] Secondly, the present invention also provides a method for controlling the prestressing self-compensation of straddle-type monorail track beams, the method comprising the following steps: S1. Perform stress wavelength calibration on the fiber optic grating sensor, determine the initial prestress reference value, and input the initial prestress reference value into the PLC controller; S2. Mark the initial compressive stress at the fiber optic grating sensor by using the product of the initial prestress and the area of ​​the resultant force of the prestressed steel bundle. S3. Use a fiber optic grating sensor to collect the real-time compressive stress of track beam 1 every half hour. S4. Calculate the difference between the initial compressive stress and the real-time compressive stress, and the ratio of the difference to the initial compressive stress to obtain the prestress loss ratio. Based on the percentage, calculate the prestress loss rate. S5. Based on engineering practice experience and relevant specifications, set the trigger threshold and termination threshold for prestress loss rate, and control the prestress loss rate to ensure that the long-term prestress loss rate of the track beam does not exceed 8%, otherwise the stiffness of the track beam will decrease by more than 10%. S6. Set the trigger threshold to 5%. When the prestress loss rate reaches the trigger threshold, the PLC controller will control the heating wire to be powered on for a short time. The solid-state relay and temperature feedback unit built into the PLC controller will control the feedback heating temperature. The PLC controller will control the heating wire to heat according to the feedback heating temperature in order to achieve fine adjustment of the contraction amount of the tie rod bundle. S7. Set the termination threshold to 3%. When the prestress loss rate reaches the compensation termination threshold, the PLC controller will send a command to stop heating the heating wire to avoid overcompensation and prevent excessive prestress in the track beam.

[0016] The beneficial effects of this invention are as follows: 1) This invention utilizes SMA tie rods for automatic compensation, effectively controlling the prestress loss rate and significantly improving the stiffness and stability of the track beam; the SMA tie rods and prestressed steel strands work together to bear the force, and there is no additional tension damage during the compensation process, which extends the fatigue life of the beam and reduces the vertical deflection at mid-span; the compensation process is completed automatically during train operation intervals without stopping operation, which greatly improves operational efficiency compared to manual tensioning.

[0017] 2) This invention utilizes the phase transformation characteristics of shape memory alloy (SMA) to generate stable supplementary prestress to control the loss rate. The compensation process does not require the shutdown of rail transit, effectively improving structural stiffness and reducing later maintenance costs. The tie rod bundles are arranged in parallel with ordinary prestressed steel bundles, and the phase transformation temperature is precisely set at 60-80℃, which satisfies both the need for low-power heating to achieve shrinkage and avoids high-temperature damage to concrete.

[0018] 3) The fiber optic grating sensor 7 of the present invention adopts a three-point pre-embedding method, that is, it is arranged at the middle and both ends of the span of the straddle-type monorail beam to accurately capture the prestress changes in the stress concentration area and set a certain loss rate threshold to trigger compensation. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is an elevation view of a straddle-type monorail beam prestressed self-compensating structure according to an embodiment of the present invention; Figure 2 This is a three-dimensional axonometric view of a straddle-type monorail beam prestressed self-compensating structure according to an embodiment of the present invention; Figure 3 This is a cross-sectional view of a straddle-type monorail beam prestressed self-compensating structure according to an embodiment of the present invention; Figure 4 This is a detailed drawing of an SMA tie rod bundle of a straddle-type monorail beam prestressed self-compensating structure according to an embodiment of the present invention. Figure 5 This is a control system diagram for automatic compensation of a prestressed self-compensating structure of a straddle-type monorail beam according to an embodiment of the present invention; Figure 6 This is a flowchart of a prestressed self-compensation control method for straddle-type monorail beams according to an embodiment of the present invention.

[0021] In the picture: 1. Track beam; 2. Anchorage; 3. Prestressed steel strands; 4. Tie rod bundle; 401. Tie rod; 5. Heating wire; 6. Insulation layer; 7. Fiber optic grating sensor; 8. Controller. Detailed Implementation

[0022] To further illustrate the various embodiments, the present invention provides accompanying drawings, which are part of the disclosure of the present invention. These drawings are mainly used to illustrate the embodiments and can be used in conjunction with the relevant descriptions in the specification to explain the operating principles of the embodiments. With reference to these drawings, those skilled in the art should be able to understand other possible implementation methods and the advantages of the present invention. The components in the drawings are not drawn to scale, and similar component symbols are generally used to represent similar components.

[0023] According to an embodiment of the present invention, a prestressed self-compensating structure for straddle-type monorail track beams is provided.

[0024] The present invention will now be further described in conjunction with the accompanying drawings and specific embodiments, such as... Figures 1-5 As shown, the configuration method according to an embodiment of the present invention includes: a track beam 1; a plurality of prestressed steel strands 3, longitudinally arranged in the web and bottom plate of the track beam 1; a tie rod bundle 4, including a plurality of tie rods 401 arranged in the center of the bottom plate of the track beam 1, and the line shape of the tie rods 401 is the same as that of the prestressed steel strands 3; a plurality of anchors 2, installed at both ends of the track beam 1, and respectively cooperating with the plurality of prestressed steel strands 3 and the tie rod bundle 4; heating wires 5, wound and arranged on the surface of the tie rod bundle 4; an insulating layer 6, installed on the outside of the heating wires 5; a plurality of fiber optic grating sensors 7, respectively embedded in the mid-span and the quarter-span positions at both ends of the track beam 1, for capturing changes in the prestress of the track beam 1; and a PLC controller 8, all connected to the plurality of fiber optic grating sensors 7 and the heating wires 5 via cables.

[0025] By utilizing the above-mentioned technical solution of the present invention, the prestress loss rate is effectively controlled by automatic compensation through SMA tie rod 4, and the stiffness and stability of the track beam 1 are significantly improved; SMA tie rod 4 and prestressed steel strand 3 are stressed together, and there is no additional tension damage during the compensation process, which extends the fatigue life of the beam and reduces the vertical deflection at mid-span; the compensation process is automatically completed during train operation intervals without the need for downtime, which greatly improves operational efficiency compared to manual tensioning.

[0026] In one embodiment, the track beam 1 has a reserved channel extending longitudinally inside the track beam 1 to cooperate with the tie rod bundle 4; the track beam 1 adopts a precast prestressed concrete PC box structure to be suitable for straddle-type monorail vehicle system, thereby improving structural economy.

[0027] Specifically, it adopts a precast prestressed concrete (PC) box girder structure, which is prefabricated in the factory and installed on site, and is suitable for straddle-type monorail vehicles.

[0028] Constrained by the straddle-type monorail vehicle structure, track beam 1 must meet the position and size requirements of the running wheels and guide wheels. Its transverse cross-section dimensions are relatively fixed, with a width of 850mm or 690mm. To improve structural economy, the beam height is also controlled. In straight sections, track beam 1 is mainly subjected to vertical and lateral swaying forces, making it a bending stiffness structure. Due to the influence of the beam cross-section's moment of inertia, adding prestressed steel strands can improve the bending resistance of track beam 1 without increasing its height.

[0029] In one embodiment, the prestressed steel strand 3 is made of several 1860MPa high-strength low-relaxation steel strands, thereby ensuring the load-bearing capacity of the track beam 1.

[0030] Specifically, multiple ordinary prestressed steel strands 3 are arranged longitudinally inside the structural track beam 1, located in the web and bottom plate of the track beam 1, and fixed at both ends of the track beam 1 by anchors 4.

[0031] Ordinary prestressed steel strands 3 are installed inside the track beam 1. The ordinary prestressed steel strands 3 are made of 1860MPa high-strength low-relaxation steel strands, with 7 strands per bundle (15.2mm in diameter). They are arranged in the web and bottom plate of the track beam 1 and fixed at both ends of the track beam 1 by anchors 2. The tension control stress is 1395MPa. After fixing, the ends are sealed to ensure the load-bearing capacity of the track beam 1.

[0032] In one embodiment, the tie rod bundle 4 is coated with a polytetrafluoroethylene coating to enhance corrosion resistance and lubrication, thereby reducing shrinkage resistance. The tie rod bundle 4 is interposed inside the reserved channel in the track beam 1, and the reserved channel is filled with an epoxy resin isolation layer that matches the tie rod bundle 4 to isolate the concrete from direct contact with the tie rod. The tie rod 401 is made of SMA shape memory alloy, thereby improving the stiffness and stability of the track beam 1.

[0033] Specifically, tie rod bundles are also installed longitudinally inside the structural track beam. Each tie rod bundle consists of 3 shape memory alloy (SMA) tie rods, which are arranged at the center of the bottom plate of the track beam. The alignment is consistent with that of ordinary prestressed steel bundles, and they are fixed at both ends of the track beam 1 by anchors.

[0034] The surface of the SMA tie rod bundle 4 is coated with polytetrafluoroethylene to enhance corrosion resistance and lubrication, and reduce shrinkage resistance; the interior of the reserved SMA tie rod bundle 4 channel is filled with an epoxy resin isolation layer to further isolate the concrete from direct contact with the tie rod 401.

[0035] Each SMA tie rod bundle 4 has a heating wire 5 spirally wound around its surface. The heating wire 5 is made of nickel-chromium material and is wrapped with a high-temperature resistant insulating layer 6. It is connected to the end of the track beam 1 via a wire. The track beam 1 has pre-drilled channels along its longitudinal direction. The SMA tie rod bundle 4 is inserted into the pre-drilled channels and fixed at both ends of the track beam 1 by anchors 2. At the same time, φ20mm inspection holes are provided at both ends of the track beam 1 to facilitate the replacement of tie rods or maintenance of heating wires in the future.

[0036] In one embodiment, the outer side of the anchor 2 is coated with a waterproof coating; the ends of the prestressed steel strand 3 and the tie rod strand 4 are both fixed with self-anchoring anchors 2; the anchor 2 is connected to the end plate of the track beam 1 by M20 high-strength bolts, and the gap between the anchor 2 and the track beam 1 is filled with rubber expansion plugs and C60 micro-expansion concrete is poured to ensure that the gap is filled tightly, thereby ensuring the sealing of the gap.

[0037] Specifically, the ends of the ordinary prestressed steel strands 3 and SMA tie rods 4 are both fixed with self-anchored anchorages 2. The anchorages 2 are connected to the end plates of the track beam 1 by M20 high-strength bolts. The gap between the anchorage and the duct is filled with rubber expansion plugs. The rubber plugs are expanded by tightening the stainless steel nuts to form a watertight seal. Waterproof coating is applied to the outside of the anchorages 2. Finally, C60 micro-expansion concrete is poured to ensure that the duct is filled tightly.

[0038] In one embodiment, for the prestressed steel strand 3, the alignment of the prestressed steel strand 3 and the alignment of the tie rod strand 4 are designed to be arranged in parallel, so as to accurately set the phase change temperature of 60-80℃.

[0039] Specifically, the tie rod bundle 4 is made of shape memory alloy (SMA). The tie rod bundle 4 is arranged in parallel with the ordinary prestressed steel bundle 3, and the phase transformation temperature is precisely set at 60-80℃, which satisfies the need for low-power heating to achieve shrinkage and avoids high-temperature damage to concrete.

[0040] In one embodiment, the heating wire 5 is made of nickel-chromium material. The insulation layer 6 is made of a high-temperature resistant material, thereby effectively controlling the prestress loss rate.

[0041] Specifically, each tie rod bundle of the structure is spirally wound with a nickel-chromium heating wire 5, and the heating wire 5 is wrapped with a high-temperature resistant insulating layer 6, which is connected to the end of the track beam 1 through a wire.

[0042] In one embodiment, the fiber Bragg grating sensor 7 is pre-embedded at three points in the middle and quarter spans of the track beam 1, with a burial depth of 30 mm to avoid areas with dense reinforcement, thereby ensuring the uniformity of the detection of the track beam 1 by the fiber Bragg grating sensor 7.

[0043] Specifically, the structure has three fiber optic grating sensors installed inside the track beam 1, which are respectively embedded in the middle and one-quarter span positions at both ends of the track beam 1 (stress concentration areas).

[0044] The monitoring sensor adopts fiber optic grating sensor 7, which is pre-embedded at three points. The fiber optic grating sensor 7 is tied at the mid-span and 1 / 4-span positions of the track beam 1. The fiber optic grating sensor 7 is buried at a depth of 30mm, avoiding areas with dense reinforcement.

[0045] like Figure 6 As shown, according to another embodiment of the present invention, a prestressed self-compensation control method for straddle-type monorail track beams is also provided, the method comprising the following steps: Step S1: Perform stress-wavelength calibration on the fiber optic grating sensor 7 to determine the initial prestress reference value, and input the initial prestress reference value into the PLC controller 8; Specifically, the fiber optic grating sensor 7 is calibrated using a stress-wavelength method to determine the initial stress reference value and input it into the PLC controller 8. The stress-wavelength method refers to the direct relationship between the wavelength signal output by the sensor and the actual stress it bears. The stress value can be obtained by fitting the equation σ (stress) = a × λ (wavelength) + b, thereby calculating the prestress loss rate.

[0046] Step S2: Mark the initial compressive stress at the fiber optic grating sensor 7 by using the product of the initial prestress and the area of ​​the combined force of the prestressed steel strand 3. Specifically, the initial compressive stress σ0 at the marked fiber optic grating sensor 7 is calculated as N0 (initial prestress) × As (area of ​​the resultant force of the prestressed steel strand 3). The prestressed steel strand 3 is composed of several prestressed steel strands, and the area of ​​the resultant force is the sum of the cross-sectional areas of each steel strand.

[0047] Step S3: Use fiber optic grating sensor 7 to collect the real-time compressive stress of track beam 1 every half hour; Specifically, during operation, operational stress is collected in real time, with the sensor collecting the real-time compressive stress σt of the concrete every 30 minutes.

[0048] Step S4: Calculate the difference between the initial compressive stress and the real-time compressive stress, and the ratio of the difference to the initial compressive stress to obtain the prestress loss ratio. Based on the percentage, calculate the prestress loss rate. Specifically, the program calculates the loss rate using the formula η=(σ0-σt) / σ0×100%.

[0049] Step S5: Based on engineering practice experience and relevant specifications, set the trigger threshold and termination threshold for prestress loss rate, and control the prestress loss rate to ensure that the long-term prestress loss rate of track beam 1 does not exceed 8%, otherwise the stiffness of track beam 1 will decrease by more than 10%. Specifically, based on engineering practice and the requirements for controlling prestress loss in standards such as the "Code for Design of Concrete Structures" GB 50010-2010 (2015 edition), the long-term prestress loss rate of PC beams should not exceed 8%, otherwise the beam stiffness will decrease by more than 10%. The trigger threshold η1 can be set to 5%, which just matches the single compensation capability of SMA tie rod 4, eliminating the need for multiple high-frequency compensations. The termination threshold η2 is set to 3% to avoid excessive compensation leading to excessive prestress in the beam.

[0050] Step S6: Set the trigger threshold to 5%. When the prestress loss rate reaches the trigger threshold, the heating wire 5 is briefly powered on by the PLC controller 8. The solid-state relay and temperature feedback unit built into the PLC controller 8 control the feedback heating temperature. The PLC controller 8 controls the heating wire 5 to heat according to the feedback heating temperature, so as to achieve fine adjustment of the contraction amount of the tie rod bundle 4. Specifically, after the entire structure of the track beam 1 is installed, the stress value is monitored in real time during operation. If the prestress loss threshold is reached, the heating wire 5 is briefly energized by the PLC controller 8. The solid-state relay and temperature feedback unit control the feedback heating temperature. The PLC controller 8 controls the heating wire 5 to heat according to the feedback heating temperature, thereby achieving fine adjustment of the SMA tie rod bundle 4 contraction amount.

[0051] Step S7: Set the termination threshold to 3%. When the prestress loss rate reaches the compensation termination threshold, send a stop heating command to the heating wire 5 through the PLC controller 8 to avoid overcompensation and prevent excessive prestress in the track beam 1.

[0052] Specifically, when the compensation termination threshold η2 is reached, the PLC controller 8 sends a stop heating command.

[0053] Specifically, PLC controller 8 is configured with preset "prestress loss threshold" and "compensation termination threshold," receives stress data from fiber optic grating sensors, synchronously calculates the loss rate, and triggers compensation commands. Based on PLC commands, the heating wire is controlled to switch on and off, and the SMA tie rod bundle temperature is monitored in real time to ensure it remains stable between 60℃ and 80℃, preventing high-temperature damage to the concrete structure.

[0054] Specifically, track beam 1 is made of C60 concrete. During pouring, a vibrator is used for compaction. The distance between the vibrator and SMA tie rod 4 and fiber optic grating sensor 7 is not less than 10cm to avoid damage to the components. Then, standard curing is carried out for 28 days. During the curing period, the sensor signals are monitored regularly to ensure that there is no damage.

[0055] According to the requirements of the standard "Technical Specification for Construction of Highway Bridges and Culverts" JTG / T 3650-2020, the ordinary prestressed steel strands 3 were tensioned. The tensioning sequence proceeded symmetrically from both ends towards the mid-span. Finally, the SMA tie rod strand 4 was preheated to 60℃-80℃ and held for 1 minute to verify the reliability of the connection between the SMA tie rod strand 4 and the anchor 2. The tensioning equipment adopted an intelligent tensioning system, which controlled the tensioning stress through the system host, oil pump, jacks, and oil pressure gauges. Stress was used as the control index, and elongation error was used as the calibration index to ensure that the tensioning met the design requirements.

[0056] The beam end wires are connected to the PLC controller 8 via a cable. The connecting cable can be armored wire. The connection between the fiber optic signal and the heating circuit is adjusted.

[0057] In summary, by utilizing the above-mentioned technical solution of this invention, the prestress loss rate is effectively controlled through automatic compensation via SMA tie rods 4, significantly improving the stiffness and stability of the track beam 1. The SMA tie rods 4 and prestressed steel strands 3 work together under stress, with no additional tension damage during the compensation process, extending the fatigue life of the beam and reducing mid-span vertical deflection. The compensation process is automatically completed during train operation intervals, eliminating the need for downtime and significantly improving operational efficiency compared to manual tensioning. This invention utilizes the phase transition characteristics of shape memory alloys (SMA) to generate stable supplementary prestress to control the loss rate. The compensation process does not require rail transit shutdown, effectively improving structural stiffness and reducing subsequent maintenance costs. The tie rod bundles 4 are arranged parallel to the ordinary prestressed steel strands 3, with a precisely set phase transition temperature of 60-80℃, satisfying both low-power heating for shrinkage and avoiding high-temperature damage to the concrete. The fiber optic grating sensor 7 of this invention is pre-embedded at three points, namely at the mid-span and both ends of the straddle-type monorail track beam 1, accurately capturing prestress changes in stress concentration areas and setting a certain loss rate threshold to trigger compensation.

[0058] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A straddle-type monorail beam prestress self-compensation structure, characterized in that, The method comprises the following steps: The track beam (1) is internally longitudinally provided with a reserved hole channel matched with the pull rod bundle (4); The track beam (1) adopts a prefabricated prestressed concrete PC box structure to be suitable for a straddle-type monorail vehicle system. The prestressed steel bundle (3) adopts a plurality of 1860MPa high-strength low-relaxation steel strands. The pull rod bundle (4) is internally provided with an epoxy resin isolation layer matched with the pull rod bundle (4) to isolate the direct contact between the concrete and the pull rod. The SMA shape memory alloy material is used for the pull rod (401). The outer side of the anchor (2) is smeared with waterproof paint; The prestressed steel bundle (3) and the pull rod bundle (4) are fixed by the self-anchored anchor (2); The anchor (2) and the end plate of the track beam (1) are connected by M20 high-strength bolts, and the gap between the anchor (2) and the hole channel of the track beam (1) is filled with a rubber expansion plug and poured with C60 micro-expansion concrete to ensure that the hole is filled densely.

2. The straddle-type monorail beam prestress self-compensation structure according to claim 1, characterized in that, The linear type of the prestressed steel bundle (3) and the linear type of the pull rod bundle (4) are designed to be parallel to accurately set the phase change temperature of 60-80℃. The heating wire (5) is made of nickel-chromium material.

3. The straddle-type monorail beam prestress self-compensation structure according to claim 1, characterized in that, The insulation layer (6) is made of high-temperature resistant material.

4. The straddle-type monorail beam prestress self-compensation structure according to claim 2, characterized in that, The fiber grating sensor (7) is bound in a three-point pre-buried manner at the midspan and quarter-span positions of the track beam (1), and the fiber grating sensor (7) is buried to a depth of 30mm to avoid the dense area of steel bars. The method comprises the following steps: S1, the stress wavelength of the fiber grating sensor (7) is calibrated, the initial prestress reference value is determined, and the initial prestress reference value is input into the PLC controller (8); 5. The straddle-type monorail beam prestress self-compensation structure according to claim 1, characterized in that, S2, the initial compressive stress at the fiber grating sensor (7) is marked by using the product of the initial prestress and the force area of the prestressed steel bundle (3). ​ ​ 6. The straddle-type monorail beam prestress self-compensation structure according to claim 1, characterized in that, ​ 7. The straddle-type monorail beam prestress self-compensation structure according to claim 1, characterized in that, ​ 8. The straddle-type monorail beam prestress self-compensation structure according to claim 1, characterized in that, ​ 9. The straddle-type monorail beam prestress self-compensation structure according to claim 1, characterized in that, ​ 10. A straddle-type monorail track beam prestress self-compensation control method, implemented based on the straddle-type monorail track beam prestress self-compensation structure of any one of claims 1-9, characterized in that, ​ ​ ​ S3, the optical fiber grating sensor (7) is used to collect the real-time compression stress of the track beam (1) every half an hour; S4, the difference between the initial compression stress and the real-time compression stress, and the ratio of the difference to the initial compression stress are calculated to obtain the prestress loss ratio, and the prestress loss rate is calculated based on the percentage; S5, based on engineering practice experience and relevant specifications, set the trigger threshold and termination threshold of the prestress loss rate, and control the prestress loss rate to ensure that the long-term prestress loss rate of the track beam (1) does not exceed 8%, otherwise the beam stiffness of the track beam (1) will decrease by more than 10%; S6, set the trigger threshold to 5%, when the prestress loss rate reaches the trigger threshold, then control the heating wire (5) to be powered on for a short time through the PLC controller (8), the solid-state relay and temperature feedback unit built in the PLC controller (8) control the feedback heating temperature, the PLC controller (8) controls the heating wire (5) to heat according to the feedback heating temperature, to realize the fine adjustment of the shrinkage amount of the tension rod bundle (4); S7, set the termination threshold to 3%, when the prestress loss rate reaches the compensation termination threshold, send the heating wire (5) stop heating instruction through the PLC controller (8) to avoid overcompensation and prevent the track beam (1) beam prestress from being too large.

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