Single-span cable-stayed bridge and design method thereof

Abstract

The application discloses a single-span cable bridge and a design method thereof, and relates to the technical field of bridge engineering design, which comprises a plurality of cross beams which are arranged in the length direction of the bridge at intervals, the top surface of the cross beam comprises a first layer and a second layer which are arranged in the up-down direction, and the first layer and the second layer each comprise an upper chord; a plurality of bolts for separating the gaps are arranged in the gaps in the width direction of the bridge at intervals; the gaps separated by the bolts are each penetrated by a main cable, and the plurality of main cables are sequentially penetrated through the plurality of cross beams in the length direction of the bridge; a transverse bridge deck is arranged on the plurality of main cables between the adjacent cross beams, and the transverse bridge deck is flush with the top surface of the cross beam; and a longitudinal bridge deck arranged in the length direction of the bridge is arranged on the top of the plurality of cross beams and the transverse bridge deck. By adopting the scheme, the bridge safety and stability are improved through the structure of the small cross beam with a small gap, and the matching of the calculation method and the structure is improved.

Description

Technical Field

[0001] This invention relates to the field of bridge engineering design technology, specifically to a single-span cableway bridge and its design method. Background Technology

[0002] A single-span cableway bridge consists of anchorages on both banks of a river, with the main cable laid between the anchorages. A bridge deck is then laid on top of the main cable, allowing vehicles to travel on it. Vehicle loads are transferred to the load-bearing main cable via the bridge deck, and the main cable then transfers the force to the anchorages on both banks. The magnitude of the stress on the main cable and anchorages depends primarily on the span and the sag of the main cable.

[0003] Its structure mainly consists of a central deck cable and two stabilizing cables on either side. The crossbeams are suspended from the stabilizing cables, and the deck cables are laid on the crossbeams. This structure cannot effectively coordinate the work of the deck cables and stabilizing cables. The main cable wire rope is usually cut on-site and erected between anchorages. After passing through pulleys on the anchorages and bending back, it is secured with rope clamps. The gap between the wire rope and the pulleys is difficult to control and increases with increasing load, which is detrimental to controlling the difference in main cable length.

[0004] There is no precise calculation theory or complete and practical design method for cableway bridge calculations, and the calculation model does not match the construction well. Generally, the influence of the above factors is considered by increasing the number of main cables. However, considering the above factors solely by increasing the number of main cables poses safety hazards and is prone to wasting materials. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention aims to provide a single-span cableway bridge and its design method. This approach not only improves the safety and stability of the bridge through the structure of closely spaced small crossbeams, but also enhances the compatibility between the calculation method and the structural design. By reducing the spacing of the steel crossbeams and minimizing the initial deviation of the main cable through prefabrication, the calculation method and structure are matched. The bridge deck is subjected to refined calculations using a subsystem, thus providing an accurate calculation theory for cableway bridge design and filling a market gap.

[0006] This invention is achieved through the following technical solution:

[0007] A single-span cableway bridge includes:

[0008] Several crossbeams are distributed at intervals along the length of the bridge. The top surface of each crossbeam includes a first layer and a second layer distributed vertically, with a gap between the first layer and the second layer. Each of the first layer and the second layer includes an upper chord. The crossbeam also includes a lower chord as the bottom surface, vertical members as the sides, and several web members connecting the top and bottom surfaces of the crossbeam.

[0009] Along the width of the bridge, a number of bolts are arranged at intervals in the gaps to separate the gaps. The bolts are threaded and welded to two upper chord members in sequence. Main cables pass through the gaps separated by the bolts, and the main cables pass through a number of crossbeams in sequence along the length of the bridge. The main cables include a number of stabilizing cables and a number of bridge deck cables.

[0010] A transverse bridge deck is laid on several main cables between adjacent crossbeams, and the transverse bridge deck is flush with the top surface of the crossbeams;

[0011] The top of several of the crossbeams and transverse bridge decks is covered with longitudinal bridge decks arranged along the length of the bridge.

[0012] This invention provides a single-span cableway bridge that not only improves bridge safety and stability through a closely spaced small crossbeam structure but also enhances the compatibility between calculation methods and structural design. The compatibility is achieved by reducing the spacing of the steel crossbeams and minimizing initial deviation of the main cables through prefabricated main cables. Specifically, the bolt ends are first bolted to the upper chord members and then welded. Several connecting rings are provided at the main cable positions on the crossbeams for the main cables to pass through. The upper and lower sides of each connecting ring are welded to the upper and lower upper chord members respectively to accommodate the main cables. The stabilizing cables on both sides are located outside the bridge deck, and several main cables are symmetrically arranged along the bridge deck centerline. The top surface of the crossbeam consists of two layers of upper chord members, allowing all bridge deck cables and stabilizing cables to be positioned between the two upper chord members of the crossbeam, leaving an installation surface for the longitudinal bridge deck panels. This close arrangement, combined with the reduction of the steel crossbeam spacing to form closely spaced small crossbeams, provides a suitable compatibility with the corresponding technical methods. In addition, the main cable adopts factory-made, assembled and refined main cable products, including steel wire ropes with factory-cast anchor heads. The main cables all adopt the pre-tensioning process, and each steel wire rope has the same stress-free length and the same initial tension. The anchor head is designed with a traction groove for easy installation. The anchor points corresponding to the main cable have the characteristic of not producing deformation, and gravity anchors can be used.

[0013] In a further embodiment, the main cables include several stabilizing cables located on both sides of the top surface of the crossbeam and several deck cables located in the middle of the top surface of the crossbeam; out-of-plane stabilizing cables are also provided on both sides of the bottom surface of the crossbeam.

[0014] Furthermore, the present invention also provides a design method for a single-span cableway bridge, comprising the following steps:

[0015] S1: Determine the overall layout of the bridge and the selection of materials and parameters for each component based on the boundary conditions at the bridge site; estimate the weight of the bridge deck system, with the weight per unit length being q; determine the main span sag f and span l; and determine the design load P.

[0016] S2: Estimate the specifications, mechanical parameters, and number of main cables n based on the main span and the weight of the bridge deck system;

[0017] S3: Under medium load conditions, analyze the structural conditions, determine the computational mechanical model of the main cable, and calculate and verify the performance parameters of the main cable;

[0018] S4: Under eccentric loading conditions, check the bearing capacity of the main cable with reference to the rigid beam method. If the bearing capacity requirement is not met, repeat steps S2-S4 to re-estimate the wire rope specifications and mechanical parameters until the bearing capacity meets the requirements.

[0019] S5: Check the lateral tilt angle. If it does not meet the requirements, repeat steps S2-S5 to re-estimate the wire rope specifications and mechanical parameters until the lateral tilt angle meets the requirements.

[0020] S6: Verify the bearing capacity of the transverse and longitudinal bridge decks respectively;

[0021] S7: Calculate the structural internal forces of the beam and verify its bearing capacity according to the eccentric load and medium load conditions;

[0022] S8: Verify the main cable bearing capacity based on the actual weight of each component, wind resistance factors, and wire rope structural parameters;

[0023] S9: Calculate the stress-free length of the main cable of the wire rope based on the physical equation of the wire rope, and design the prefabricated main cable and anchorage based on the final stress-free length of the main cable.

[0024] In a further embodiment, step S3 includes the following specific steps:

[0025] Under medium load conditions, the structural conditions are analyzed, and the small sag theory is used for calculation. The corresponding formula is: Calculate and verify the main cable, where H is the maximum tension of the cable and M is the mid-span bending moment of the corresponding simply supported beam; find And f is obtained according to the main cable conversion formula. 静 and H 静 ;f 静 and H 静 These represent the sagittal and cable tension in the completed bridge configuration, respectively; H i Let be the tension in the i-th main cable.

[0026] In a further embodiment, step S4 also includes the following specific steps:

[0027] S41: Calculate the main cable deflection based on the central arrangement of the bridge design load, which is the main cable design sag f;

[0028] S42: Study the design load under unit eccentric loading: Consider the transverse bridge deck as a rigid plate, and the increase in deformation at the corresponding position of each main cable is δ. i =ai *tanα; corresponds to the increase in the load shared by the main cable. The corresponding increase in cable force is Then, using the equilibrium condition, α can be obtained; subsequently, ΔH for each main cable can be calculated. i ;

[0029] S43: Calculate the ordinate value of the influence line for each main cable based on different eccentricities, draw the lateral distribution influence line for each main cable, and calculate the increase in internal force ΔH due to the lateral distribution influence of the load on each main cable, assuming the most unfavorable load arrangement. imax ;

[0030] S44: Based on the increase in eccentric loading, the internal force (H) i +ΔH imax ) Verify the bearing capacity of the main cable. Under eccentric loading, the relationship between the differential displacement of each main cable and the cable force can be linearly changed. At this time, the nonlinear problem of the main cable calculation is transformed into an elastic-like problem within a small range of the design sag. If H does not meet the bearing capacity requirements at this time, repeat steps S2-S4 to re-estimate the wire rope specifications and mechanical parameters until the bearing capacity meets the requirements.

[0031] In a further embodiment, step S4 also includes the following specific steps:

[0032] S45: After obtaining the maximum tension H of the cable under the influence of eccentric loading, the main cable can also be verified by the finite element method according to the model considering the influence of initial deviation; and the local increase in tension of the main cable between the crossbeams is calculated by applying the design load to the cableway bridge composed of the maximum crossbeam spacing and the bridge deck cables with the span as the whole span. This calculated value is added to the overall calculated tension of the main cable under the influence of eccentric loading to obtain the design value of the tension of the bridge deck cables.

[0033] S46: Perform the load-bearing capacity verification again. If H does not meet the load-bearing capacity requirements at this time, repeat steps S2-S4 to re-estimate the wire rope specifications and mechanical parameters until the load-bearing capacity meets the requirements.

[0034] In a further embodiment, step S5 also includes the following specific steps:

[0035] When verifying the lateral tilt angle, the increase in deformation Δ is calculated based on step S4 when the maximum cable force is reached in each main cable. i α is obtained by calculating tanα from the distance ai from the main cable to the centerline of the cross-section. max Perform a verification calculation. If the requirements are not met, repeat steps S2-S5 to re-estimate the wire rope specifications and mechanical parameters until the lateral inclination angle meets the requirements.

[0036] In a further embodiment, step S6 also includes the following specific steps:

[0037] S61: When verifying the bearing capacity of the longitudinal bridge deck, the bow height of the main cable and the longitudinal bridge deck is obtained according to the main cable profile and the length of the longitudinal bridge deck under the design load. The bending moment value Mzb1 when the longitudinal bridge deck undergoes the corresponding deformation of the bow height is obtained according to the bow height.

[0038] S62: Calculate the main cable deformation Δ using the design load applied to a cableway bridge composed of the maximum crossbeam spacing and deck cables with a span equal to the full span. zs (At this time, the main cable tension is set to H) i calculate)

[0039] S63: The deformation Δ of a simply supported beam subjected to the design load equivalent to the longitudinal length of the bridge deck. zb ;

[0040] S64: The design load is distributed proportionally according to the relative relationship between the two deformation quantities, that is, the load borne by the main cable is... The longitudinal bridge deck bears the load of calculate The main cable deforms under the action as follows

[0041] S65: In CAD, draw the shape of the main cable between the crossbeams according to the catenary curve. Measure the deformation value at the corresponding position of each transverse bridge deck based on this drawing. Calculate the supporting force of each transverse bridge deck on the longitudinal bridge deck using force balance. The sum of the supporting forces of each transverse bridge deck is equal to... Furthermore, the supporting force and deformation value of each transverse bridge deck are directly proportional; the maximum bending moment design value of the longitudinal bridge deck is obtained based on the support reaction force of the transverse bridge deck, and then added to Mzb1, and the strength is verified by mechanics of materials.

[0042] In a further embodiment, step S6 also includes the following specific steps:

[0043] When verifying the transverse bridge deck, based on the abstract mechanical model, it is simulated as a plate under the elastic support of the main cable for calculation. The supporting force borne by the corresponding transverse bridge deck is evenly distributed within the width range of the longitudinal bridge deck. Then, the internal force of the transverse bridge deck is calculated using the influence line based on the uniformly distributed load and the supporting force of the main cable. The influence line of the transverse bridge deck is drawn using the influence line of the main cable in step S43. The internal force of the transverse bridge deck is calculated according to the most unfavorable load arrangement. The internal force is verified by conventional methods.

[0044] In a further embodiment, step S8 includes the following specific steps:

[0045] S81: Recheck the main cable bearing capacity based on the actual weight of the bridge deck system and related components. If it does not meet the requirements, repeat steps S2-S8 to re-estimate the wire rope specifications and mechanical parameters until the bearing capacity meets the requirements.

[0046] S82: After considering the influence of wind cable tension based on the wind resistance calculation results, check the main cable bearing capacity. If it does not meet the requirements, repeat steps S2-S8 to re-estimate the wire rope specifications and mechanical parameters until the bearing capacity meets the requirements.

[0047] S83: After the materials arrive on site, weigh all components and measure the structural parameters of the wire rope products. Based on the measurement results, verify the main cable bearing capacity. If it does not meet the requirements, repeat steps S2-S8 to re-estimate the wire rope specifications and mechanical parameters until the bearing capacity meets the requirements.

[0048] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0049] This invention provides a single-span cableway bridge and its design method. This approach not only improves the safety and stability of the bridge through the structure of closely spaced small crossbeams, but also enhances the compatibility between the calculation method and the structural design. The main cable employs a near-rigid crossbeam method, improving calculation accuracy. By reducing the spacing of the steel crossbeams and minimizing the initial deviation of the main cable through prefabrication, the matching of the calculation method and the structural design is achieved. The bridge deck is subjected to refined calculations using a subsystem approach, thus providing an accurate calculation theory for cableway bridge design and filling a market gap. Attached Figure Description

[0050] To more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be considered as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort. In the drawings:

[0051] Figure 1 This is a side view of a single-span cableway bridge provided by the present invention;

[0052] Figure 2 The AA cross-sectional view of the single-span cableway bridge provided by the present invention.

[0053] The attached diagram shows the markings and corresponding component names:

[0054] 1-Crossbeam, 101-Upper chord, 102-Lower chord, 103-Vertical member, 104-Bolt, 105-Web member, 2-Main cable, 201-Stabilizing cable, 202-Bridge deck cable, 3-Out-of-plane stabilizing cable, 4-Longitudinal bridge deck, 5-Anchorage, 6-Guardrail. Detailed Implementation

[0055] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments and accompanying drawings. The illustrative embodiments and descriptions of the present invention are only used to explain the present invention and are not intended to limit the present invention.

[0056] Example 1:

[0057] This embodiment 1 provides a single-span cableway bridge, such as Figure 1 and Figure 2 As shown, it includes:

[0058] Several crossbeams 1 are distributed at intervals along the length of the bridge. The top surface of each crossbeam 1 includes a first layer and a second layer distributed vertically, with a gap between the first layer and the second layer. Each of the first layer and the second layer includes an upper chord 101. The crossbeam 1 also includes a lower chord 102 as the bottom surface, vertical members 103 as the side surface, and several web members 105 connecting the top and bottom surfaces of the crossbeam 1.

[0059] Along the width of the bridge, a plurality of bolts 104 are arranged at intervals in the gap to separate the gap. The bolts 104 are threaded and welded to two upper chord members 101 in sequence. A main cable 2 passes through each gap separated by the bolts 104. The main cables 2 pass through a plurality of crossbeams 1 in sequence along the length of the bridge. The main cables 2 include a plurality of stabilizing cables 201 and a plurality of bridge deck cables 202.

[0060] A transverse bridge deck is laid on several main cables 2 between adjacent crossbeams 1, and the transverse bridge deck is flush with the top surface of the crossbeam 1;

[0061] Several of the aforementioned crossbeams 1 and the top of the transverse bridge deck are covered with longitudinal bridge deck 4 arranged along the length of the bridge.

[0062] This invention provides a single-span cableway bridge that not only improves the safety and stability of the bridge through the structure of closely spaced small crossbeams 1, but also enhances the matching between the calculation method and the structural design. The matching between the calculation method and the structure is achieved by reducing the spacing of the steel crossbeams 1 and by reducing the initial deviation of the main cables through prefabricated main cables 2. Specifically, the ends of bolts 104 are first connected to the upper chord 101 and then welded. Several connecting rings are provided at the positions of the main cables 2 on the crossbeams 1 for the main cables 2 to pass through. The upper and lower sides of the connecting rings are welded to the upper and lower upper chords 101 respectively to accommodate the main cables 2. The stabilizing cables 201 located on the left and right sides are all outside the bridge deck, and several main cables 2 are symmetrically arranged along the centerline of the bridge deck. The top surface of the crossbeam 1 consists of two layers of upper chords 101, allowing all bridge deck cables 202 and stabilizing cables 201 to be positioned between the two upper chords 101 of the crossbeam, while leaving an installation surface for the longitudinal bridge deck 4. This close arrangement, combined with reducing the spacing of the steel crossbeams 1 to form closely spaced small crossbeams 1, provides a suitable match for the corresponding technical methods. Furthermore, the main cables utilize factory-produced, assembled, and refined main cable products, including wire ropes with factory-cast anchor heads. The main cables 2 all employ a pre-tensioning process, ensuring that each wire rope has the same stress-free length and initial tension. The anchor heads are designed with traction grooves for easy installation. The anchorages 5, corresponding to the anchor points of the main cables, are designed to prevent deformation and can be gravity-type anchorages, etc.

[0063] In a further embodiment, the main cables 2 include a number of stabilizing cables 201 disposed on both sides of the top surface of the crossbeam 1 and a number of bridge deck cables 202 disposed in the middle of the top surface of the crossbeam 1; and out-of-plane stabilizing cables 3 are also disposed on both sides of the bottom surface of the crossbeam 1.

[0064] Example 2:

[0065] This embodiment 2 further optimizes the first embodiment by matching the above-mentioned structure with the corresponding calculation method, thus providing a design method for a single-span cableway bridge, including the following specific steps:

[0066] First, the overall bridge layout needs to be determined based on the boundary conditions at the bridge site, including the cable saddle positions (determining the main span) and the main cable anchorage positions. The construction scheme is determined as follows: the main cables utilize factory-produced, prefabricated, and refined main cable products, with a single main cable structure including steel wire ropes with factory-cast anchor heads. All main cables employ a pre-tensioning process, ensuring each steel wire rope has the same stress-free length and initial tension. The anchor heads are designed with traction grooves for easy installation. The anchorages corresponding to the main cables have the characteristic of not causing deformation; gravity anchorages, etc., can be used. The crossbeam 1 adopts a closely spaced small crossbeam form, with all bridge deck cables 202 and stabilizing cables 201 positioned between the two upper chord members 101 of the crossbeam (see attached diagram). The bridge deck consists of a bottom layer of transverse strip panels and an upper layer of large-sized transverse integral longitudinal segmented panels, with both ends of the upper panel corresponding to the positions of the crossbeam 1.

[0067] Design process or structural calculation steps:

[0068] 1.1: Estimated weight of bridge deck system (weight per unit length q).

[0069] 1.2: Determine the design vector f and span l of the main span, and determine the design load P.

[0070] 1.3: Based on the main span and the weight of the bridge deck system, estimate the specifications, mechanical parameters, and number of main cables n of the wire ropes by referring to similar projects.

[0071] 1.4: Main Cable Calculation: 1) Under medium load: Analyze the structural conditions and determine the main cable calculation mechanical model (using the small sag theory to calculate the corresponding formula is as follows). H represents the maximum tension of the cable, and M represents the mid-span bending moment of the corresponding simply supported beam. This scheme uses prefabricated main cable wire ropes and closely spaced small crossbeams 1, which ensures uniform stress on the main cable. Therefore, the main cable can be considered as sharing the live load and its own weight load. The stress characteristics of the main cable satisfy the small sag elastic theory, and the main cable is calculated and verified according to this theory. The cable force of a single main cable is... Then use the conversion formula to find f 静 and H 静 The formula is:

[0072] H2 3 +B*H2 2 -C = 0;

[0073]

[0074] H1 and H2 represent the horizontal tension of the main cable under the known and desired conditions, respectively; E and A represent the elastic modulus and cross-sectional area of ​​the main cable, respectively; Q1 and Q2 represent the shear force of the simply supported beam under the known and desired conditions, respectively.

[0075] 2) Under eccentric loading: According to the "Rigid Beam Method 1" (when calculating eccentric loading, first calculate the main cable deflection f based on the central arrangement of the bridge design load, and then study the situation under unit eccentric loading: at this time, the transverse bridge deck is considered as a rigid plate, and the deformation increase at the corresponding position of each main cable is δ). i =a i *tanα; The increase in design load distributed across each main cable is... The corresponding increase in cable tension is (This formula applies only to ±10% H) i (within); then use the equilibrium condition to obtain α; and then obtain ΔH for each main cable. iThen, based on different eccentricities, the ordinate values ​​of the influence lines of each main cable are calculated (n is the number of main cables, ai is the distance from the main cable to the centerline of the cross-section, and α is the bridge deck inclination angle). The lateral distribution influence lines of each main cable are then drawn. With the most unfavorable load arrangement, the increase in internal force ΔH due to the lateral distribution influence of each main cable is calculated. imax Then, based on the increase in eccentric load, the internal force (H) is... i +ΔH imax Verify the main cable bearing capacity. Under eccentric loading, the increase in differential displacement of each main cable and the cable force can be linearly related. In this case, the nonlinear problem of main cable calculation is transformed into a quasi-elastic problem within a small range of design sag. If H does not meet the bearing capacity requirement at this time, repeat steps 1.3-1.4 until the bearing capacity meets the requirement. The main cable can also be verified using the finite element method with a model considering the influence of initial deviation. Because the close crossbeam 1 system and the quasi-rigid crossbeam 1 method are used, it is not necessary to distinguish between the load acting on the crossbeams and between the crossbeams when calculating the main cable. At the same time, to improve the simplicity of the design method, the increase in local tension of the main cable between crossbeams 1 is calculated by applying the design load to the cableway bridge composed of the maximum crossbeam 1 spacing and bridge deck cables 202 with a span of the full span (at this time, the cable force of the completed bridge is H). i Calculate the local tension under the design load using the conversion formula. Add this calculated value to the overall calculated (considering eccentric load) main cable tension to obtain the design tension value of bridge deck cable 202. Then, verify the bearing capacity. If H does not meet the bearing capacity requirements at this point, repeat steps 1.3-1.4 until the bearing capacity meets the requirements. The difference between this value and the stabilizing cable force of cable 201 considering the eccentric load should be within ±10% for optimal design.

[0076] 1.5: Verify the lateral tilt angle (based on the deformation increase Δ calculated in the previous step when the maximum cable force is reached for each main cable). i α obtained by tanα with ai max (Verification), if not satisfied, repeat steps 1.3-1.5.

[0077] 1.6: Bridge Deck Calculation: The calculation of the bridge deck is divided into the upper longitudinal bridge deck and the lower transverse bridge deck. Longitudinal Bridge Deck Calculation: First, considering the influence of the overall alignment on the bridge deck's bearing capacity, the bow height between the main cable and the bridge deck is measured in CAD based on the main cable alignment and the longitudinal bridge deck length under the design load. The bending moment value Mzb1 when the longitudinal bridge deck undergoes the corresponding deformation at this bow height is then calculated. Second, the bearing capacity of the longitudinal bridge deck between crossbeams 1 is calculated by applying the design load to the cableway bridge composed of the maximum crossbeam spacing and bridge deck cables 202, calculating the main cable deformation Δ. zs (At this time, the horizontal tension of the main cable is taken as H) i The sagitta f0 corresponding to this tension can be obtained using the small sag theory. Then, the deformation under the design load can be obtained according to the main cable transformation formula. The deformation Δ is calculated as the design load acting on a simply supported beam equivalent to the longitudinal bridge deck length.zb The design load is distributed proportionally according to the relative relationship between the two deformations, that is, the load borne by the main cable is... The longitudinal bridge deck bears the load of calculate The main cable deforms under the action as follows In CAD, draw the shape of the main cable in section 1 of the crossbeam according to the catenary curve. Measure the deformation value at the corresponding position of each transverse bridge deck based on this drawing. Then, use force balance to calculate the supporting force of each transverse bridge deck on the longitudinal bridge deck (i.e., the sum of the supporting forces of each transverse bridge deck equals...). Furthermore, the supporting force of each transverse bridge deck is proportional to its deformation value. The maximum bending moment design value of the longitudinal bridge deck is obtained based on the support reaction force of the transverse bridge deck, and then added to Mzb1. The strength is verified using mechanics of materials. An abstract mechanical model of the transverse bridge deck is used, simulating it as a plate under the elastic support of the main cable for calculation. The supporting force borne by the corresponding transverse bridge deck is uniformly distributed within the width range of the longitudinal bridge deck. Then, based on the influence line of the uniformly distributed load and the supporting force of the main cable, the internal force of the transverse bridge deck is calculated (using the influence line of the main cable in 1.4 to draw the influence line of the transverse bridge deck, arranging the load according to the most unfavorable arrangement, calculating the internal force of the transverse bridge deck, and verifying the internal force using conventional methods).

[0078] 1.7: Calculate the structural internal forces of beam 1 under eccentric and medium load conditions and verify its bearing capacity (draw the influence line of beam 1 using the main cable influence line in 1.4, calculate the internal forces of beam 1 according to the most unfavorable load arrangement, and verify the internal forces using conventional methods.)

[0079] 1.8: Recheck the main cable bearing capacity based on the actual weight of the bridge deck system and related components. If it does not meet the requirements, repeat the steps after 1.3.

[0080] 1.9: After considering the influence of wind cable tension based on the wind resistance calculation results, check the main cable bearing capacity. If it does not meet the requirements, repeat the steps after 1.3.

[0081] 1.10: After the materials arrive on site, all components are weighed, and the elastic modulus, weight and effective cross-sectional area of ​​the wire rope products are measured. The main cable bearing capacity is then verified based on the measured results.

[0082] 1.11: Calculate the stress-free length of the main cable of the wire rope based on the physical equation of the wire rope. f is the maximum sag of the main cable, and l is the span of the main cable.

[0083] Finally, based on the final stress-free length of the main cable, prefabricate the main cable and anchorage; complete the design of the anchor saddle and other structures using conventional methods; and compile the design documents.

[0084] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A design method for a single-span cableway bridge, characterized in that, The invention includes a single-span cableway bridge, the single-span cableway bridge comprising: A number of crossbeams (1) are distributed at intervals along the length of the bridge. The top surface of the crossbeams (1) includes a first layer and a second layer distributed vertically, with a gap between the first layer and the second layer. Both the first layer and the second layer include an upper chord (101). The crossbeams (1) also include a lower chord (102) as the bottom surface, a vertical bar (103) as the side surface, and a number of web members (105) connecting the top surface and the bottom surface of the crossbeams (1). Along the width of the bridge, a number of bolts (104) are arranged at intervals in the gap to separate the gap. The bolts (104) are threaded and welded to two upper chords (101) in sequence. A main cable (2) passes through the gap separated by the vertical bars (104). The main cables (2) pass through a number of crossbeams (1) in sequence along the length of the bridge. The main cables (2) include a number of stabilizing cables (201) and a number of bridge deck cables (202). A transverse bridge deck is laid on several main cables (2) between adjacent crossbeams (1), and the transverse bridge deck is flush with the top surface of the crossbeam (1); Several of the aforementioned crossbeams (1) and the top of the transverse bridge deck are covered with longitudinal bridge decks (4) arranged along the length of the bridge. The design method includes the following steps: S1: Determine the overall layout of the bridge and the selection of materials and parameters for each component based on the boundary conditions at the bridge site; estimate the weight of the bridge deck system, with the weight per unit length being q; determine the main span sag f and span l; and determine the design load P. S2: Estimate the specifications, mechanical parameters, and number of main cables n based on the main span and the weight of the bridge deck system; S3: Under medium load conditions, analyze the structural conditions, determine the computational mechanical model of the main cable, and calculate and verify the performance parameters of the main cable; S4: Under eccentric loading conditions, check the bearing capacity of the main cable with reference to the rigid beam method. If the bearing capacity requirement is not met, repeat steps S2-S4 to re-estimate the wire rope specifications and mechanical parameters until the bearing capacity meets the requirements. S5: Check the lateral tilt angle. If it does not meet the requirements, repeat steps S2-S5 to re-estimate the wire rope specifications and mechanical parameters until the lateral tilt angle meets the requirements. S6: Verify the bearing capacity of the transverse and longitudinal bridge decks respectively; S7: Calculate the structural internal forces of the beam (1) under eccentric load and medium load conditions and verify its bearing capacity; S8: Verify the main cable bearing capacity based on the actual weight of each component, wind resistance factors, and wire rope structural parameters; S9: Calculate the stress-free length of the main cable of the wire rope based on the physical equation of the wire rope, and design the prefabricated main cable and anchorage based on the final stress-free length of the main cable; Step S4 further includes the following specific steps: S41: Calculate the main cable deflection based on the central arrangement of the bridge design load, which is the main cable design sag f; S42: Study the design load under unit eccentric loading: Consider the transverse bridge deck as a rigid plate, and the increase in deformation at the corresponding position of each main cable is... The corresponding increase in the load shared by the main cable is... The corresponding increase in cable tension is Then, using the equilibrium condition, we can obtain... ; and then the properties of each main cable are obtained. Where n is the principal search root number, a i The distance from the main cable to the centerline of the cross-section. f is the bridge deck inclination angle; f is the main span sag. and These are the sagitta and cable tension in the completed bridge configuration, respectively. S43: Calculate the ordinate value of the influence line for each main cable based on different eccentricities, draw the lateral distribution influence line for each main cable, and calculate the increase in internal force due to the lateral distribution influence of the load on each main cable according to the most unfavorable load arrangement. ; S44: Based on the increase in eccentric load, the internal forces ( + ) Verify the bearing capacity of the main cable. Under eccentric loading, the relationship between the differential displacement of each main cable and the cable force can be linearly changed. At this time, the nonlinear problem of the main cable calculation is transformed into an elastic-like problem within a small range of the design sag. If H does not meet the bearing capacity requirements at this time, repeat steps S2-S4 to re-estimate the wire rope specifications and mechanical parameters until the bearing capacity meets the requirements.

2. The design method for a single-span cableway bridge according to claim 1, characterized in that, The main cables include several stabilizing cables (201) disposed on both sides of the top surface of the crossbeam (1) and several deck cables (202) disposed in the middle of the top surface of the crossbeam (1); and out-of-plane stabilizing cables (3) are also disposed on both sides of the bottom surface of the crossbeam.

3. The design method for a single-span cableway bridge according to claim 1, characterized in that, Step S3 includes the following specific steps: Under medium load conditions, the structural conditions are analyzed, and the small sag theory is used for calculation. The corresponding formula is: The main cable is calculated and verified, where H is the maximum tension of the cable, M is the mid-span bending moment of the corresponding simply supported beam, and f is the main span sag; [Calculate / determine] And obtain it according to the main cable conversion formula. and .

4. The design method for a single-span cableway bridge according to claim 1, characterized in that, Step S4 further includes the following specific steps: S45: After obtaining the maximum tension H of the cable under the influence of eccentric loading, the main cable can also be verified by the finite element method according to the model considering the influence of initial deviation; and the local increase in tension of the main cable between the crossbeams is calculated by applying the design load to the cableway bridge composed of the maximum crossbeam spacing and the bridge deck cables with the span as the whole span. This calculated value is added to the overall calculated tension of the main cable under the influence of eccentric loading to obtain the design value of the tension of the bridge deck cables. S46: Perform the load-bearing capacity verification again. If H does not meet the load-bearing capacity requirements at this time, repeat steps S2-S4 to re-estimate the wire rope specifications and mechanical parameters until the load-bearing capacity meets the requirements.

5. The design method for a single-span cableway bridge according to claim 1, characterized in that, Step S5 further includes the following specific steps: When verifying the lateral tilt angle, the increase in deformation is calculated based on step S4 when the maximum cable force is reached for each main cable. The distance ai from the main cable to the centerline of the cross-section is calculated according to tan obtained Perform a verification calculation. If the requirements are not met, repeat steps S2-S5 to re-estimate the wire rope specifications and mechanical parameters until the lateral inclination angle meets the requirements.

6. The design method for a single-span cableway bridge according to claim 1, characterized in that, Step S6 further includes the following specific steps: S61: When verifying the bearing capacity of the longitudinal bridge deck, the bow height of the main cable and the longitudinal bridge deck is obtained according to the main cable profile and the length of the longitudinal bridge deck under the design load. The bending moment value Mzb1 when the longitudinal bridge deck undergoes the corresponding deformation of the bow height is obtained according to the bow height. S62: Calculate the main cable deformation using the design load applied to a cableway bridge composed of the maximum crossbeam spacing and deck cables with a span equal to the full span. ; S63: Deformation of a simply supported beam subjected to design loads equivalent to the longitudinal length of the bridge deck. ; S64: The design load is distributed proportionally according to the relative relationship between the two deformation quantities, that is, the load borne by the main cable is... P, the load borne by the longitudinal bridge deck is P, calculate The deformation of the principal cable under the action of P is: ; S65: In CAD, draw the shape of the main cable between the crossbeams according to the catenary curve. Measure the deformation value at the corresponding position of each crossbeam deck based on this drawing. Calculate the supporting force of each transverse deck on the longitudinal deck using force balance. The sum of the supporting forces of each transverse deck is equal to... P, and the supporting force of each transverse bridge deck is proportional to the deformation value; The maximum bending moment design value of the longitudinal bridge deck is obtained based on the support reaction force of the transverse bridge deck, and then added to Mzb1. The strength is then verified using the mechanics of materials.

7. The design method for a single-span cableway bridge according to claim 6, characterized in that, Step S6 further includes the following specific steps: When verifying the transverse bridge deck, based on the abstract mechanical model, it is simulated as a plate under the elastic support of the main cable for calculation. The supporting force borne by the corresponding transverse bridge deck is evenly distributed within the width range of the longitudinal bridge deck. Then, the internal force of the transverse bridge deck is calculated using the influence line based on the uniformly distributed load and the supporting force of the main cable. The influence line of the transverse bridge deck is drawn using the influence line of the main cable in step S43. The internal force of the transverse bridge deck is calculated according to the most unfavorable load arrangement. The internal force is verified by conventional methods.

8. The design method for a single-span cableway bridge according to claim 1, characterized in that, Step S8 includes the following specific steps: S81: Recheck the main cable bearing capacity based on the actual weight of the bridge deck system and related components. If it does not meet the requirements, repeat steps S2-S8 to re-estimate the wire rope specifications and mechanical parameters until the bearing capacity meets the requirements. S82: After considering the influence of wind cable tension based on the wind resistance calculation results, check the main cable bearing capacity. If it does not meet the requirements, repeat steps S2-S8 to re-estimate the wire rope specifications and mechanical parameters until the bearing capacity meets the requirements. S83: After the materials arrive on site, weigh all components and measure the structural parameters of the wire rope products. Based on the measurement results, verify the main cable bearing capacity. If it does not meet the requirements, repeat steps S2-S8 to re-estimate the wire rope specifications and mechanical parameters until the bearing capacity meets the requirements.

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