Adaptive temperature compensation type large-span arch bridge main arch truss section connecting device

Abstract

A self-adaptive temperature compensation type large-span arch bridge main arch truss section connecting device belongs to the field of bridge engineering structures, and comprises two groups of SMA (Shape Memory Alloy) elastic gaskets which are clamped between two adjacent main arch truss section flange plates, are symmetrically arranged up and down and are made of shape memory alloys; the prestress tension screws penetrate through the flange plates on the two sides and the SMA elastic gaskets, and high-strength nuts are arranged at the two ends of each prestress tension screw in a matched mode; the two ends of the hydraulic damper are detachably connected with the flange plates of the adjacent sections through spherical hinges respectively; the SMA elastic gasket is a wave-shaped NiTi alloy thin plate; the hydraulic damper has the beneficial effects that the SMA elastic gasket can dynamically absorb and compensate axial displacement caused by thermal expansion and cold contraction, the hydraulic damper can dynamically absorb and compensate radial displacement caused by vibration, accurate initial pre-tightening force can be applied to the SMA gasket by properly tightening the high-strength nut, and the fault-tolerant capability is improved.

Description

Technical Field

[0001] This invention relates to the field of bridge engineering structures, and in particular to an adaptive temperature-compensated main arch truss segment connection device for long-span arch bridges. Background Technology

[0002] Long-span arch bridges are iconic structures in modern bridge engineering, and their main arch trusses are often constructed using prefabricated segments in the factory and assembled on-site. During the construction and operation of long-span arch bridges, the reliability of the main arch truss segment connections directly affects the overall structural safety of the bridge. Currently, high-strength bolts or on-site welding are commonly used for segmental connections. However, these traditional methods have significant technical drawbacks.

[0003] First, long-span arch bridges are extremely sensitive to temperature effects. Under the influence of non-uniform temperature fields such as solar radiation, a significant temperature difference of over 20°C can occur between the upper and lower chords of the arch rib, leading to enormous axial temperature deformation in the arch truss segments. In a statically indeterminate structural system, this deformation, when constrained, generates significant additional secondary internal forces due to temperature variations, severely impacting structural safety and long-term fatigue life.

[0004] Secondly, rigid connections lack effective deformation coordination capabilities. The enormous energy generated by temperature deformation cannot be effectively absorbed or released, ultimately concentrating as high stress in the area surrounding the weld or bolt holes, which can easily induce fatigue cracks and create structural safety hazards.

[0005] To address the aforementioned issues, existing technologies have attempted to compensate by adding gaskets of fixed thickness between flanges. However, this method is a form of "static compensation," which cannot respond to complex and variable environmental temperatures, has limited compensation effectiveness, and cannot adapt to geometric errors present during construction. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide an adaptive temperature-compensated main arch truss segment connection device and connection method for large-span arch bridges, which can achieve automatic dynamic compensation within a temperature change range of ±30℃, effectively suppress stress concentration, and have excellent tolerance for construction errors.

[0007] To solve the above-mentioned technical problems, the technical solution adopted in this invention is an adaptive temperature-compensated main arch truss segment connection device for long-span arch bridges, comprising: two sets of SMA elastic gaskets made of shape memory alloy arranged symmetrically between flanges of two adjacent main arch truss segments; a prestressed tensioning bolt penetrating the flanges on both sides and the SMA elastic gaskets, with high-strength nuts at both ends of the prestressed tensioning bolt; and a hydraulic damper that is detachably connected to the flanges of adjacent segments by ball joints at both ends.

[0008] The SMA elastic gasket has a corrugated thin plate structure and is made of NiTi shape memory alloy with a phase transformation temperature range of -50℃ to 50℃, covering the temperature change of use from -45℃ to 45℃. At room temperature (25℃), the elastic modulus is 28 to 30 GPa, and the superelastic deformation is 8% to 10%, achieving dynamic thermal deformation compensation. The prestressed tensioning bolts are generally set with 4 to 32 pieces, and the hydraulic dampers are generally set with 1 to 8 pieces.

[0009] An adaptive temperature-compensated method for connecting main arch truss segments of a long-span arch bridge includes the following steps: (1) Between the flange of the first main arch truss segment and the flange of the second main arch truss segment, two sets of SMA elastic gaskets made of shape memory alloy are arranged symmetrically in an upper and lower position. Each set of SMA elastic gaskets consists of 2-4 pieces stacked together.

[0010] (2) Multiple prestressed tensioning bolts are used to pass through the flanges on both sides and the SMA elastic gasket. High-strength nuts are fitted at both ends of the bolts. The initial preload is applied to the SMA elastic gasket by tightening the high-strength nuts, so that the SMA elastic gasket produces initial elastic deformation.

[0011] (3) A hydraulic damper is connected between the flange of the first main arch truss segment and the flange of the second main arch truss segment. The two ends of the hydraulic damper are detachably connected to the flanges of the adjacent segments through ball joints. The ball joint structure can adapt to the small angular displacement between segments, and the hydraulic damper can absorb the vibration energy caused by temperature changes or loads and suppress stress concentration.

[0012] Furthermore, the waveform of the wave-shaped thin plate structure is a sine wave, a trapezoidal wave, or a circular arc wave.

[0013] Furthermore, the wave-shaped structure of the SMA elastic gasket is: wave height 5~8mm, wavelength 15~25mm, and the ratio of wave height H to wavelength λ, H / λ, is between 0.2 and 0.5. This ensures that the maximum deformation compensation of a single set of gaskets is ≥10mm, and two sets working together can achieve ≥20mm of axial displacement compensation, thus better optimizing its deformation capacity and fatigue performance.

[0014] Furthermore, the SMA elastic pad has a mesh pattern or wear-resistant coating formed by laser etching at the crests and troughs to increase friction and prevent relative slippage.

[0015] Furthermore, the diameter of the screw holes on the flange is 1-2 mm larger than the outer diameter of the high-strength prestressed screw.

[0016] Furthermore, the number of hydraulic dampers is two or four, and they are arranged symmetrically around the flange circumference to provide uniform damping energy dissipation and connection constraints.

[0017] The damping coefficient of the hydraulic damper is 40kN·s / m to 60kN·s / m, and the stroke is ±40mm to ±60mm; the installation angle of the hydraulic damper is 40° to 50° with the flange plane.

[0018] Compared with the prior art, the present invention has the following beneficial effects: (1) Adaptive temperature compensation: NiTi alloy SMA gaskets can dynamically respond to temperature changes within a range of ±30℃, exhibiting excellent superelasticity. When changes in ambient temperature cause thermal expansion and contraction of the main arch truss segments, the SMA elastic gaskets can dynamically absorb and compensate for axial displacement through the elastic deformation of their wave-shaped structure, directly converting temperature changes into mechanical displacement compensation, significantly reducing temperature-induced internal forces. Its compensation behavior is entirely temperature-driven, requiring no external energy or control, achieving true "automatic response and self-adaptation".

[0019] (2) Dual mechanical tools working in synergy: The SMA elastic gasket is primarily responsible for slow, quasi-static temperature loads. Its hyperelastic platform provides a nearly constant restoring force, keeping the nodal stress stable over a wide deformation range, completely avoiding stress concentration, ensuring uniform stress distribution, and preventing peak stresses generated locally in rigid connections, thus significantly improving the fatigue resistance of the joint; the hydraulic damper is primarily responsible for fast, dynamic wind-induced vibrations and seismic loads. Energy is dissipated through fluid throttling, while the ball joint design eliminates additional bending moments, ensuring the damper's working efficiency and multi-directional deformation adaptability, improving the overall dynamic performance of the bridge; the two are complementary rather than simply superimposed in function, each addressing loads of different frequencies and natures, synergistically improving the comprehensive mechanical performance of the joint.

[0020] (3) Strong construction error tolerance: By properly tightening the high-strength nuts, a precise initial preload can be applied to the SMA gasket. This preload can flatten part of the gasket's waveform, thereby actively adjusting and compensating for possible manufacturing and installation errors during segment splicing, ensuring the tightness of the connection; it can simplify the construction adjustment process and improve error tolerance. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the overall structure of the adaptive temperature compensation type main arch truss segment connection device for large-span arch bridges according to the present invention.

[0022] Figure 2 This is a schematic diagram of the cross-sectional structure of the SMA elastic gasket in this invention.

[0023] In the figure: 1. Flange of the first main arch truss segment, 2. Flange of the second main arch truss segment, 3. SMA elastic gasket, 4. Prestressed tensioning bolt, 5. High-strength nut, 6. Hydraulic damper, 7. Ball joint, 8. Ear plate, 9. Wear-resistant coating. Detailed Implementation

[0024] The present invention will be further illustrated below with simulated examples from three different climatic environments. These examples are intended to illustrate the present invention and not to further limit it, and should not be construed as limiting the scope of protection of the present invention. Example 1:

[0025] An adaptive temperature-compensated connection was designed for the main arch truss segments of a long-span steel truss arch bridge in temperate regions. Simulation tests were conducted with a design span of 500m and a temperature range of -20℃ to 45℃. The following equipment was used: The flanges on the main arch truss segments are made with an outer diameter of 1200mm, an inner diameter of 800mm, and a thickness of 50mm. Twelve bolt holes with a diameter of 32mm are evenly arranged at 200mm intervals along the circumference of the flange.

[0026] Prepare two sets of SMA elastic gasket assemblies: each set uses 3 stacked corrugated thin plates with a thickness of 6mm, a wave height of 7mm, a wavelength of 22mm, and a wave height / wavelength ratio of 0.318. The material is NiTi alloy, and the phase transformation temperature range of this NiTi alloy is between -50℃ and 50℃, which can ensure that it maintains super elasticity within ±45℃.

[0027] Pre-stressed tensioning bolts: 12 M30 high-strength bolts made of 40CrNiMoA material, each equipped with 4 high-strength nuts.

[0028] Preparatory hydraulic dampers: Two unidirectional hydraulic dampers are selected, with a damping coefficient of 50kN·s / m and a stroke of ±50mm; the dampers are filled with high-temperature resistant hydraulic oil (-40℃~80℃); the ball joints at both ends of the dampers are made of GCr15 bearing steel.

[0029] Installation steps: 1. Pre-treatment: Clean the connection surfaces of flange 1 of the adjacent first main arch truss segment and flange 2 of the second main arch truss segment to ensure that there is no oil or rust.

[0030] 2. Shape memory training of SMA elastic gaskets: Deformation training is performed 10 times under cyclic loading stress for 24 hours within the temperature range of -20℃ to 45℃ to ensure phase transformation stability.

[0031] 3. Install SMA elastic gaskets: Place two sets of SMA elastic gaskets 3 onto the upper and lower symmetrical positions of the flange 1 of the first main arch truss segment, with a symmetrical spacing of 600mm. Set bolt holes at the corresponding positions of the SMA elastic gaskets.

[0032] 4. Connecting flanges: Align the flange 2 of the second main arch truss segment with the flange 1 of the first main arch truss segment that is fitted with the SMA elastic gasket 3, and ensure that the bolt holes are coaxial.

[0033] 5. Install prestressed tensioning bolts and perform prestressing: Insert 12 prestressed tensioning bolts 4 through the bolt holes of the flange and SMA elastic gaskets 3, screw high-strength nuts into both ends, and set two sets of high-strength nuts and elastic nut gaskets at each end. Use a torque wrench to tighten the nuts in a symmetrical sequence, control the tightening torque to 800 N·m, and apply an initial preload of 100 kN to the SMA elastic gaskets 3.

[0034] 6. Install hydraulic dampers: Connect the two hydraulic dampers to the connecting lugs on the outside of the flange via ball joints, ensuring that the installation angle of the hydraulic dampers is at a 45° angle to the flange plane. After installation, perform a sealing test: introduce 0.5MPa compressed air and maintain the pressure for 30 minutes without leakage. Example 2:

[0035] An adaptive temperature-compensated connection simulation test was conducted on the main arch truss segment of a large-span steel truss arch bridge in a high-temperature and high-humidity region. The design span was 500m, the temperature range was -10℃ to 40℃, and the environment was high-salinity. The following equipment was used: The flanges on the main arch truss segments are made with an outer diameter of 1200mm, an inner diameter of 800mm, and a thickness of 50mm. Sixteen bolt holes with a diameter of 30mm are evenly arranged at 150mm intervals along the circumference of the flange.

[0036] Prepare two sets of SMA elastic gaskets: each set contains 4 stacked corrugated thin plates with a sinusoidal cross section, a plate thickness of 6mm, a wave height of 5mm, a wavelength of 15mm, a wave height / wavelength ratio of 1 / 3, and a material of NiTi alloy. The phase transformation temperature range of this NiTi alloy is between -45℃ and 45℃, which can ensure super elasticity within ±40℃.

[0037] Pre-stressed tensioning bolts: 16 M28 high-strength bolts made of 40CrNiMoA material, each equipped with 4 high-strength nuts.

[0038] Preparatory hydraulic dampers: Four unidirectional hydraulic dampers are selected, with a damping coefficient of 60kN·s / m and a stroke of ±40mm; the dampers are filled with high-temperature resistant hydraulic oil (-40℃~80℃), and the ball joints at both ends of the dampers are made of GCr15 bearing steel.

[0039] Installation steps: 1. Pre-treatment: Clean the connection surfaces of flange 1 of the adjacent first main arch truss segment and flange 2 of the second main arch truss segment to ensure that there is no oil or rust.

[0040] 2. Shape memory training of SMA elastic gaskets: Deformation training is performed 10 times under cyclic loading stress for 24 hours within a temperature range of -10℃ to 40℃ to ensure phase transformation stability.

[0041] 3. Install SMA elastic gaskets: Place two sets of SMA elastic gaskets 3 onto the upper and lower symmetrical positions of the flange 1 of the first main arch truss segment, with a symmetrical spacing of 600mm. Set bolt holes at the corresponding positions of the SMA elastic gaskets.

[0042] 4. Connecting flanges: Align the flange 2 of the second main arch truss segment with the flange 1 of the first main arch truss segment that is fitted with the SMA elastic gasket 3, and ensure that the bolt holes are coaxial.

[0043] 5. Install prestressed tensioning bolts and perform prestressing: Insert 16 prestressed tensioning bolts 4 through the bolt holes of the flange and SMA elastic gaskets 3, screw high-strength nuts into both ends, and set two sets of high-strength nuts and elastic nut gaskets at each end. Use a torque wrench to tighten the nuts in a symmetrical sequence, control the tightening torque to 850 N·m, and apply an initial preload of 110 kN to the SMA elastic gaskets 3.

[0044] 6. Install hydraulic dampers: Connect the four hydraulic dampers to the connecting lugs on the outside of the flange via ball joints, ensuring that the installation angle of the hydraulic dampers is at a 50° angle to the flange plane. After installation, perform a sealing test: introduce 0.5MPa compressed air and maintain the pressure for 30 minutes without leakage. Example 3:

[0045] An adaptive temperature-compensated connection simulation test was conducted on the main arch truss segment of a large-span steel truss arch bridge in a cold temperate region. The design span was 500m, with a temperature range of -35℃ to 25℃. The following equipment was used: The flanges on the main arch truss segments are made with an outer diameter of 1200mm, an inner diameter of 800mm, and a thickness of 50mm. Eight bolt holes with a diameter of 33mm are evenly arranged at 300mm intervals along the circumference of the flange.

[0046] Prepare two sets of SMA elastic gaskets: each set contains two superimposed corrugated thin plates with a sinusoidal cross section, a plate thickness of 6mm, a wave height of 8mm, a wavelength of 25mm, a wave height / wavelength ratio of 0.32, and a NiTi alloy material. The phase transformation temperature range of this NiTi alloy is between -40℃ and 40℃, which can ensure superelasticity within ±35℃.

[0047] Pre-stressed tensioning bolts: 8 M32 high-strength bolts made of 40CrNiMoA material, each equipped with 4 high-strength nuts.

[0048] Preparatory hydraulic dampers: 8 unidirectional hydraulic dampers are selected, with a damping coefficient of 40kN·s / m and a stroke of ±60mm; the dampers are filled with high-temperature resistant hydraulic oil (-40℃~80℃), and the ball joints at both ends of the dampers are made of GCr15 bearing steel.

[0049] Installation steps: 1. Pre-treatment: Clean the connection surfaces of flange 1 of the adjacent first main arch truss segment and flange 2 of the second main arch truss segment to ensure that there is no oil or rust.

[0050] 2. Shape memory training of SMA elastic gaskets: Deformation training is performed 10 times under cyclic loading stress for 24 hours within the temperature range of -35℃ to 25℃ to ensure phase transformation stability.

[0051] 3. Install SMA elastic gaskets: Place two sets of SMA elastic gaskets 3 onto the upper and lower symmetrical positions of the flange 1 of the first main arch truss segment, with a symmetrical spacing of 600mm. Set bolt holes at the corresponding positions of the SMA elastic gaskets.

[0052] 4. Connecting flanges: Align the flange 2 of the second main arch truss segment with the flange 1 of the first main arch truss segment that is fitted with the SMA elastic gasket 3, and ensure that the bolt holes are coaxial.

[0053] 5. Install prestressed tensioning bolts and perform prestressing: Insert 8 prestressed tensioning bolts 4 through the bolt holes of the flange and SMA elastic gaskets 3, screw high-strength nuts into both ends, and set two sets of high-strength nuts and elastic nut gaskets at each end. Use a torque wrench to tighten the nuts in a symmetrical sequence, control the tightening torque to 750 N·m, and apply an initial preload of 90 kN to the SMA elastic gaskets 3.

[0054] 6. Install hydraulic dampers: Connect the 8 hydraulic dampers to the connecting lugs on the outside of the flange via ball joints, ensuring that the installation angle of the hydraulic dampers is at a 40° angle to the flange plane. After installation, perform a sealing test: introduce 0.5MPa compressed air and maintain the pressure for 30 minutes without leakage.

[0055] Experimental results verification: After adopting the adaptive temperature compensation type connection device, the actual measured results after simulating the highest summer ambient temperature of 42℃ and the lowest winter ambient temperature of -28℃ are shown in the table below:

[0056] The axial deformation compensation of the arch rib can reach ±25mm, completely covering the deformation caused by temperature change of ±45℃; the maximum stress value of the flange connection is 120MPa, which is 57% lower than the maximum stress of 280MPa of the traditional rigid flange connection, and the stress concentration factor is less than 1.20, which is far lower than the stress concentration factor limit of 1.80 corresponding to steel fatigue, and the stress concentration suppression effect is significant; during construction, when the parallelism deviation of the flange is ≤3mm, the preload of the SMA gasket can be ensured by adjusting the torque of the high-strength nut to 800±50N·m, which meets the requirements for construction error tolerance; it can be seen that this connection device can be adapted to different harsh environments and has stable mechanical properties.

Claims

1. An adaptive temperature-compensated main arch truss segment connection device for a long-span arch bridge, comprising: Two sets of SMA elastic gaskets made of shape memory alloy are arranged symmetrically between the flanges of two adjacent main arch truss segments. The SMA elastic gaskets are corrugated thin plate structures. A prestressed tensioning rod passes through both flanges and the SMA elastic gaskets. The prestressed tensioning rods are equipped with high-strength nuts at both ends. A hydraulic damper is detachably connected to the flanges of adjacent segments through ball joints at both ends.

2. The adaptive temperature-compensated main arch truss segment connection device for long-span arch bridges according to claim 1, characterized in that... Its connection method includes the following steps: (1) Two sets of SMA elastic gaskets made of shape memory alloy are arranged symmetrically between the flanges of the adjacent first main arch truss segment and the flange of the second main arch truss segment. (2) Multiple prestressed tensioning bolts are used to pass through the flanges on both sides and the SMA elastic gasket. High-strength nuts are used to tighten the ends of the bolts. The initial preload is applied to the SMA elastic gasket by tightening the high-strength nuts, so that the SMA elastic gasket produces initial elastic deformation. (3) A hydraulic damper is connected between the flanges of the first main arch truss segment and the second main arch truss segment. The two ends of the hydraulic damper are detachably connected to the flanges of the adjacent segments via ball joints.

3. The adaptive temperature-compensated main arch truss segment connection device for long-span arch bridges according to claim 2, characterized in that... The waveform of the wave-shaped thin plate structure is a sine wave, a trapezoidal wave, or a circular arc wave.

4. The adaptive temperature-compensated main arch truss segment connection device for long-span arch bridges according to claim 3, characterized in that... In the wavy structure of the SMA elastic gasket, the ratio of wave height H to wavelength λ, H / λ, is between 0.2 and 0.

5.

5. The adaptive temperature-compensated main arch truss segment connection device for a long-span arch bridge according to claim 4, characterized in that... The SMA elastic pad has a mesh pattern or wear-resistant coating formed by laser etching at the crests and troughs.

6. The adaptive temperature-compensated main arch truss segment connection device for a long-span arch bridge according to claim 5, characterized in that... The SMA elastic gasket is made of NiTi alloy.

7. The adaptive temperature-compensated main arch truss segment connection device for a long-span arch bridge according to claim 6, characterized in that... The phase transformation temperature range of the NiTi alloy is -50℃ to 50℃.

8. The adaptive temperature-compensated main arch truss segment connection device for a long-span arch bridge according to claim 7, characterized in that... The damping coefficient of the hydraulic damper is 40kN·s / m to 60kN·s / m, and the stroke is ±40mm to ±60mm.

9. The adaptive temperature-compensated main arch truss segment connection device for a long-span arch bridge according to claim 8, characterized in that... The installation angle of the hydraulic damper is 40° to 50° with the flange plane.

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