A large-span ground-anchored composite beam cable-stayed bridge and construction method thereof

Abstract

The invention discloses a large-span ground-anchored composite beam cable-stayed bridge and a construction method thereof, comprising cable towers located at both sides of the cable-stayed bridge and abutments located outside the cable towers, wherein concrete beams are respectively arranged on the inner sides of the abutments, steel-concrete combined sections are respectively arranged on the inner ends of the concrete beams, steel-UHPC composite beams are respectively connected to the inner ends of the two steel-concrete combined sections, and an adaptive connection device is arranged between the inner ends of the steel-UHPC composite beams; the adaptive connection device comprises two large box beams respectively fixedly connected to the steel-UHPC composite beams, a plurality of box chambers are arranged in the middle of the large box beams along the length direction of the bridge, a sliding support mechanism is arranged on the inner periphery of the box chamber, the sliding support mechanism is connected to a guide beam, and a damping shock-absorbing structure and an expansion joint are arranged between the two large box beams; cables connected to the cable towers are respectively arranged on the abutments, the concrete beams and the steel-UHPC composite beams; the invention has the advantages of outstanding spanning capacity, stable performance of the adaptive connection device and good bridge deck performance.

Description

Technical Field

[0001] The invention belongs to the technical field of bridge engineering, and in particular relates to a large-span ground-anchored composite beam cable-stayed bridge and a construction method thereof. Background Art

[0002] A cable-stayed bridge is a type of bridge that uses many cables to directly pull the main beam onto the bridge tower. It is a structural system that is composed of a compression tower, tension cables, and a bending beam. The cable anchorage section of the cable tower of a cable-stayed bridge is an important load-bearing component that safely and evenly transfers the concentrated force of the cable to the tower column, and can prevent the tower wall concrete from cracking under the strong concentrated force of the cable. A long-span bridge generally refers to a bridge with a single span of more than 100 meters.

[0003] In the case where the side-to-mid span ratio is too small to be taken as the value of a conventional cable-stayed bridge due to terrain conditions, the ground-anchored cable-stayed bridge can adapt to the terrain of special zones with relatively small side-to-mid spans. Due to the special structure of the ground-anchored cable-stayed bridge, a non-axial force connection device that allows the main beam to slide longitudinally is required in the mid-span to release the axial force.

[0004] In the prior art, the ground-anchored cable-stayed bridge has problems with the fragility, durability and driving comfort of the central axial force-free connection device, as well as the problem of easy fatigue of the orthogonal anisotropic slab bridge deck. Summary of the invention

[0005] The purpose of the present invention is to address the problems existing in the prior art and to provide a large-span ground-anchored composite beam cable-stayed bridge and a construction method thereof, which has the advantages of outstanding spanning capacity, stable performance of an adaptive connection device, and good bridge deck performance.

[0006] To achieve the above-mentioned purpose, the technical solution adopted by the present invention is: a large-span ground-anchored composite beam cable-stayed bridge, comprising cable towers located on both sides of the cable-stayed bridge and ground-anchored abutments located outside the cable towers, concrete beams are respectively arranged on the inner sides of the two abutments, steel-concrete combined sections are respectively arranged at the inner ends of the two concrete beams, steel-UHPC composite beams are respectively connected to the inner ends of the two steel-concrete combined sections, and an adaptive connection device is arranged between the inner ends of the steel-UHPC composite beams; the adaptive connection device comprises two large box beams respectively fixedly connected to the steel-UHPC composite beams, a plurality of box chambers are arranged in the middle part of the large box beams along the length direction of the bridge, a sliding support mechanism is arranged on the inner periphery of the box chamber, the sliding support mechanism is connected to a guide beam, and a damping shock absorbing structure and an expansion joint are arranged between the two large box beams; a plurality of cables connected to the cable towers are respectively arranged on the abutments, concrete beams and steel-UHPC composite beams.

[0007] In the above scheme, both ends of the bridge beam are fixed on the abutments, cables are arranged on the cable towers to provide tension to the concrete beams and the steel-UHPC composite beams, the abutments are connected to the cable towers by zippers to balance the forces on both sides of the cable towers, the bridge beam includes concrete beams at the side spans and steel-UHPC composite beams at the middle spans, the steel structure of the steel-UHPC composite beams is connected by pouring concrete by arranging a steel-concrete combined section, a connection transition is made between the concrete beams and the steel-UHPC composite beams, the two sections of the steel-UHPC composite beams are connected by an adaptive connection device, and the main beams are allowed to slide longitudinally relative to each other to release the axial force; the large box beam of the adaptive connection device is connected and fixed to the steel box structure of the steel-UHPC composite beam, a box chamber is provided in the middle of the cross-sectional direction of the large box beam, and sliding supports are provided along the circumference of the box chamber The mechanism is connected to the guide beam, and the sliding support mechanism provides lateral and vertical support forces between the guide beam and the two large box beams to position the two. The damping shock-absorbing structure is a non-rigidity, speed-related energy-absorbing and shock-absorbing device. When the bridge is under the static load (such as temperature, vehicle gravity) or the static component of the dynamic load, the damping shock-absorbing structure can slowly displace; when the bridge is under the dynamic load of the vehicle, the damping shock-absorbing structure plays the function of speed locking and locks the steel beams on both sides of the expansion joint; when the bridge is under wind-induced vibration and seismic load, the damping shock-absorbing structure plays the function of viscous damping, dissipates energy, and significantly reduces the relative displacement and relative speed of the expansion joint along the bridge, greatly reduces the vibration of the steel beam, and protects the bridge. An expansion joint is set between the two large box beams to meet the deformation requirements of the bridge deck and ensure smooth traffic on the bridge deck.

[0008] The adaptive connection device can adaptively release and adjust the damping lock under different stress conditions, so that the structural stress is always in the best state, realizing the conversion of different working conditions of the guide beam, and arbitrary conversion from bidirectional to unidirectional operation; the life of the structure is doubled; and it has the conditions to complete all maintenance, care and repair under the operating state.

[0009] The cable-stayed bridge towers are separated and the beams and abutments are consolidated. The bridge and the towers have no vertical supports and are separated. The main beam and the ground-anchored abutments are connected together. UHPC refers to ultra-high performance concrete.

[0010] Furthermore, two ends of the guide beam are provided with limit adjustment structures.

[0011] A limit adjustment structure is provided for limit adjustment of the guide beam in the length direction of the bridge to ensure that the guide beam is located at the center of the bridge, thereby improving the stress conditions of the guide beam and the main beam.

[0012] Furthermore, the limit adjustment structure includes an adjusting screw, one end of which is connected to the steel-UHPC composite beam or the large box beam, and the other end of which is used to be connected to the guide beam; during normal operation, the guide beam is connected to the adjusting screw on one side.

[0013] Under normal working conditions, the guide beam and the adjustment screws at both ends are used alternately. When the main beam is affected by temperature and deforms, the guide beam limit screw is in a locked state, forming a fixed hinge constraint, locking the position of one end of the guide beam and allowing the other end to slide freely, thereby releasing the longitudinal relative displacement of both ends of the steel beam. When the main beam is subjected to vehicle loads, the guide beam and the main beam produce a large displacement. After long-term accumulation, by adjusting the screw, the guide beam can be adjusted in different working states and the relative position of the guide beam between the main beams can be adjusted to ensure that the guide beam is located in the center of the bridge, thereby improving the stress conditions of the guide beam and the main beam.

[0014] Furthermore, the steel-UHPC composite beam comprises a steel box beam and a UHPC bridge deck layer, the steel-concrete combined section comprises a steel joint, and the steel box beam and the steel joint are welded.

[0015] The UHPC bridge deck is cast on the steel box girder. Compared with the steel-precast concrete slab composite beam cable-stayed bridge with similar span, there is no need to set up a special prefabrication site for the concrete bridge deck, the number of joints is reduced by more than 60%, and the weight of the beam section per square meter can be reduced by about 50% or 30% respectively; compared with the steel box girder with orthotropic steel deck, the weight of the beam section per square meter increases by no more than 10%, but the longitudinal and transverse bending stiffness of the bridge deck increases by 50% and 5400% respectively, the local hot spot stress of the steel bridge deck decreases by 20-80%, and the fatigue resistance and durability of the bridge deck are greatly improved.

[0016] The UHPC surface layer and the steel box girder participate in the stress of the first structural system throughout the whole process. The utilization rate of UHPC compressive strength is nearly 90%, the material utilization rate is high, the structure is light, durable, and has good bearing performance. It effectively solves the problems of fatigue and easy damage of pavement of conventional steel bridge decks, and the heavy weight and low crack resistance of concrete bridge deck structures in steel-concrete combined sections, and avoids the need to use ultra-thick steel plates in extra-large span steel main beams.

[0017] Furthermore, the abutment includes a box-type concrete structure, and a plurality of vertical CFRP anchor rods are arranged at the bottom of the abutment.

[0018] CFRP anchor refers to carbon fiber reinforced composite anchor. The abutment uses a cavity box concrete structure. The CFRP anchor is installed by drilling holes in the foundation pit, and the holes are filled with ultra-high performance concrete (UHPC) bonding medium. While meeting the pull-out requirements of the abutment, the base burial depth is greatly reduced, and the height of the abutment is reduced, thereby effectively reducing the lateral earth pressure of the abutment, improving its lateral anti-sliding safety factor, and greatly reducing the amount of abutment concrete and the amount of foundation pit excavation; the rock anchor point is arranged close to the cable anchor point, and the vertical component of the cable can be directly transmitted to the bedrock through the rock anchor cable. The force transmission path is simple and significantly improves the stress state of the concrete side wall of the abutment; the rock anchor bolt also serves as the vertical prestressed tendon of the abutment body, and the ground anchor abutment itself also serves as a retaining wall, with outstanding comprehensive functions. Based on ultra-high performance concrete (UHPC) bonding medium and carbon fiber reinforced composite material (CFRP) tendon anchor, a rock anchor-gravity combined light ground anchor abutment structure system with efficient anchoring and excellent durability is formed.

[0019] Furthermore, the span ratio of the concrete beam to the steel-UHPC composite beam is in the range of 0.18-0.21.

[0020] The mid-span deflection of the main beam and the lateral displacement of the tower top under live load indicate that when the side-to-mid-span ratio is in the range of 0.18-0.21, the overall stiffness of the structural system is in a relatively good state.

[0021] Furthermore, the damping and shock absorbing structure is a speed locker.

[0022] The damping shock absorbing structure has speed locking and viscous damping functions and can be a speed locker.

[0023] Furthermore, the sliding support mechanism includes a spherical bearing.

[0024] The large box girder and the guide beam are connected by spherical bearings, which can provide shock absorption and buffering, stabilize the connection, and allow the guide beam and the large box girder to slide relative to each other along the length of the bridge.

[0025] The ball bearing uses an ultra-high performance polytetrafluoroethylene spherical slide bearing.

[0026] A construction method for a large-span ground-anchored composite beam cable-stayed bridge is used to construct the large-span ground-anchored composite beam cable-stayed bridge, comprising the following steps:

[0027] Step 1: constructing the cable tower, ground-anchored abutment and concrete beam;

[0028] Step 2: Carry out the construction of the steel-concrete joint section and install the inclined cables simultaneously;

[0029] Step 3: Hoist the steel-UHPC composite beam to the work station, complete the welding of the steel main beam of the steel-UHPC composite beam between segments and the pouring of the UHPC wet joints, and simultaneously hang the inclined cables;

[0030] Step 4: Hoist the adaptive connection device to the work station, carry out the connection construction between the adaptive connection device and the steel-UHPC composite beam, and complete the docking of the bridge.

[0031] In the above scheme, in step one, the cable towers and abutments are constructed at the bridge sites on both sides, first the pile foundation and the abutment are built and then the cable towers are built, and the concrete beams are constructed on the abutments, which can be constructed simultaneously on both sides; in step two, the steel-concrete combined section is constructed at the inner end of the concrete beam to prepare for the steel box structure connection of the steel-UHPC composite beam, and the cable-stayed cable is installed; in step three, the steel-UHPC composite beam can be prefabricated, transported to the site for direct hoisting for installation, welding the steel-UHPC composite beam and installing the cable-stayed cable; in step four, the adaptive connection device can be directly prefabricated and hoisted to the installation site in the center of the bridge, the large box beam and the steel structure of the steel-UHPC composite beam are welded, the concrete structure of the bridge deck is poured, and the bridge is connected.

[0032] Furthermore, the concrete beam is constructed by full-bridge support, and the ground-anchored abutment is constructed by turnover formwork.

[0033] The full-span support and overmolding method are used to ensure a stable structure. The support can be removed after the steel-UHPC composite beam is installed.

[0034] Furthermore, the steel-UHPC composite beams and the adaptive connection devices are prefabricated parts.

[0035] Prefabricated steel-UHPC composite beams and adaptive connection devices can reduce the construction workload and cycle on site.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] (I) In this scheme, the cable-stayed bridge structure has separated beams and towers, and the beam abutments are consolidated. The bridge uses concrete beams combined with steel-UHPC composite beams to reduce the burden on the cables while ensuring the bending stiffness of the bridge. It can span a large span and has a strong spanning capacity. It is combined with a smaller-scale ground-anchored abutment structure to adapt to terrains with relatively small side and middle spans such as mountain valleys;

[0038] (ii) The large box girder and steel-UHPC composite beam of the adaptive connection device release the axial force through the sliding connection between the guide beam and the large box girder, and the expansion joint on the adaptive connection device ensures the driving comfort at the connection. The speed locking and viscous damping effect of the damping and shock absorbing structure are combined to solve the problem that the fragility and durability of the adaptive connection device do not meet the requirements;

[0039] (iii) UHPC bridge deck reduces the number of joints and the weight of beam segments on the basis of ordinary concrete bridge decks, increases the bending stiffness of orthotropic steel bridge deck beams, and greatly improves fatigue resistance and durability;

[0040] (iv) Setting limit adjustment structures on both sides of the guide beam to prevent the guide beam from being displaced too much, facilitating the adjustment of the guide beam position, improving the stress conditions of the guide beam and the main beam, and keeping the guide beam in the best operating state. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 is a general diagram of the bridge in Example 1 of the present invention;

[0042] Figure 2 is an installation diagram of the adaptive connection device in Example 1 of the present invention;

[0043] Figure 3 This is a top view of the installation of the adaptive connection device in Example 1 of the present invention;

[0044] Figure 4 This is a schematic diagram of the installation of the guide beam in Embodiment 1 of the present invention;

[0045] Figure 5 This is a schematic diagram of the installation of the damping and shock absorbing structure in Example 1 of the present invention;

[0046] Figure 6 This is a top view of the installation of the damping and shock absorbing structure in Example 1 of the present invention;

[0047] Figure 7 for Figure 6 AA section diagram in;

[0048] Figure 8 It is a structural schematic diagram of the abutment in Embodiment 1 of the present invention;

[0049] Fig. 9 for Figure 8 Cross-section diagram at FF and GG;

[0050] Fig.10 This is a schematic diagram of the installation of CFRP anchor rods in the abutment in Example 1 of the present invention;

[0051] In the figure: 1. Cable tower; 2. Abutment; 3. Concrete beam; 4. Steel-concrete combined section; 5. Steel-UHPC composite beam; 6. Expansion joint; 7. Large box beam; 8. Box chamber; 9. Sliding support mechanism; 10. Guide beam; 11. Damping and shock absorption structure; 12. Cable; 13. Limit adjustment structure; 14. CFRP anchor rod. DETAILED DESCRIPTION

[0052] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0053] Example 1

[0054] like Figure 1-10 As shown, a large-span ground-anchored composite beam cable-stayed bridge comprises cable towers 1 located on both sides of the cable-stayed bridge and ground-anchored abutments 2 located outside the cable towers 1, concrete beams 3 are respectively arranged on the inner sides of the two abutments 2, steel-concrete combined sections 4 are respectively arranged at the inner ends of the two concrete beams 3, steel-UHPC composite beams 5 are respectively connected to the inner ends of the two steel-concrete combined sections 4, and an adaptive connection device is arranged between the inner ends of the steel-UHPC composite beams 5; the adaptive connection device comprises two large box beams 7 respectively fixedly connected to the steel-UHPC composite beams 5, a plurality of box chambers 8 are arranged in the middle part of the large box beams 7 along the length direction of the bridge, a sliding support mechanism 9 is arranged on the inner periphery of the box chambers 8, the sliding support mechanism 9 is connected to a guide beam 10, and a damping shock absorbing structure 11 and an expansion joint 6 are arranged between the two large box beams 7; a plurality of cables 12 connected to the cable towers 1 are respectively arranged on the abutments 2, the concrete beams 3 and the steel-UHPC composite beams 5.

[0055] In the above scheme, both ends of the bridge beam are fixedly arranged on the abutment 2, and cables 12 are arranged on the cable tower 1 to provide tension to the concrete beam 3 and the steel-UHPC composite beam 5. The abutment 2 is connected to the cable tower 1 by a zipper to balance the forces on both sides of the cable tower 1. The bridge beam includes the concrete beam 3 of the side span and the steel-UHPC composite beam 5 of the middle span. The steel-concrete combined section 4 is provided to connect the steel structure of the steel-UHPC composite beam 5 by pouring concrete, and a connection transition is made between the concrete beam 3 and the steel-UHPC composite beam 5. The two sections of the steel-UHPC composite beam 5 are connected by an adaptive connection device, allowing the main beam to slide longitudinally relative to each other to release the axial force; the large box beam 7 of the adaptive connection device is connected and fixed to the steel box structure of the steel-UHPC composite beam 5, and a box chamber 8 is opened in the middle of the cross-sectional direction of the large box beam 7, and sliding supports are arranged along the circumference of the box chamber 8. The support mechanism 9 is connected to the guide beam 10, and the sliding support mechanism 9 provides support forces between the guide beam 10 and the two large box beams 7 in the horizontal and vertical directions to position the two. The damping shock absorbing structure 11 is a non-rigidity, speed-related energy-absorbing shock absorbing device. When the bridge is under the static load (such as temperature, car gravity) or the static component of the dynamic load, the damping shock absorbing structure 11 can slowly displace; when the bridge is under the dynamic load of the vehicle, the damping shock absorbing structure 11 plays the function of speed locking, locking the steel beams on both sides of the expansion joint 6; when the bridge is under wind-induced vibration and seismic load, the damping shock absorbing structure 11 plays the function of viscous damping, dissipating energy, significantly reducing the relative displacement and relative speed of the expansion joint 6 along the bridge, greatly reducing the vibration of the steel beam, and protecting the bridge. The expansion joint 6 is set between the two sections of the large box beams 7 to meet the deformation requirements of the bridge deck and ensure smooth driving on the bridge deck.

[0056] In the embodiment, the sliding support mechanism 9 uses an ultra-high performance polytetrafluoroethylene spherical skateboard support, and four box chambers 8 are opened horizontally in the middle of the large box beam 7. Two groups of skateboard supports are arranged along the length direction of each box chamber 8. Each group of spherical skateboard supports includes two skateboard spherical supports respectively arranged on the left and right sides of the box chamber 8, and a spherical skateboard support respectively arranged on the upper and lower sides of the box chamber 8.

[0057] The adaptive connection device can adaptively perform damping lock release and adjustment under different stress conditions, so that the structural stress is always in the best state, realizing the conversion of different working conditions of the guide beam 10, and arbitrary conversion from bidirectional to unidirectional operation; the structural life is doubled; and it has the conditions to complete all maintenance, care, and repairs in the operating state, as well as the conditions for replacing the bearings.

[0058] The cable-stayed bridge tower is separated and the beam and abutment are consolidated. The bridge and the cable tower 1 have no vertical support and are separated. The bridge and the abutment 2 are connected together. The structure can refer to the separation of the main beam and anchor of the suspension bridge. UHPC refers to ultra-high performance concrete.

[0059] Furthermore, limit adjustment structures 13 are provided at both ends of the guide beam 10 .

[0060] The limit adjustment structure 13 is provided for limit adjustment of the guide beam 10 in the length direction of the bridge, so as to ensure that the guide beam 10 is located at the center of the bridge, thereby improving the stress conditions of the guide beam 10 and the main beam.

[0061] Furthermore, the limit adjustment structure 13 includes an adjusting screw, one end of which is connected to the steel-UHPC composite beam 5 or the large box beam 7, and the other end of which is used to be connected to the guide beam 10; during normal operation, the guide beam 10 is connected to the adjusting screw on one side.

[0062] Under normal working conditions, the guide beam 10 and the adjusting screw rods at both ends are used alternately. When the main beam is affected by temperature and produces temperature deformation, the limit screw rod of the guide beam 10 is in a locked state, forming a fixed hinge constraint, locking the position of one end of the guide beam 10, and the other end slides freely, thereby releasing the longitudinal relative displacement of the two ends of the steel beam. When the main beam is subjected to vehicle load, the guide beam 10 and the main beam produce a large displacement. After long-term accumulation, by adjusting the screw rod, it is possible to adjust the guide beam 10 in different working states and adjust the relative position of the guide beam 10 between the main beams to ensure that the guide beam 10 is located in the center of the bridge, thereby improving the stress conditions of the guide beam 10 and the main beam.

[0063] The adjusting screw comprises a screw and a sleeve. The sleeve is hinged to the guide beam 10 . A threaded hole is arranged in the sleeve to cooperate with the screw. The screw is rotatably connected to a hinged portion, and the hinged portion is bolted to the base of the steel-UHPC composite beam 5 .

[0064] Furthermore, the steel-UHPC composite beam 5 includes a steel box beam and a UHPC bridge deck layer, the steel-concrete combined section 4 includes a steel joint, and the steel box beam and the steel joint are welded.

[0065] The UHPC bridge deck is cast on the steel box girder. Compared with the steel-precast concrete slab composite beam cable-stayed bridge with similar span, there is no need to set up a special prefabrication site for the concrete bridge deck, the number of joints is reduced by more than 60%, and the weight of the beam section per square meter can be reduced by about 50% or 30% respectively; compared with the steel box girder with orthotropic steel deck, the weight of the beam section per square meter increases by no more than 10%, but the longitudinal and transverse bending stiffness of the bridge deck increases by 50% and 5400% respectively, the local hot spot stress of the steel bridge deck decreases by 20-80%, and the fatigue resistance and durability of the bridge deck are greatly improved.

[0066] The UHPC surface layer and the steel box girder participate in the stress of the first structural system throughout the whole process. The utilization rate of UHPC compressive strength is nearly 90%, the material utilization rate is high, the structure is light, durable, and has good bearing performance. It effectively solves the problems of fatigue and easy damage of pavement of conventional steel bridge decks, and the heavy weight and low crack resistance of the concrete bridge deck structure in the steel-concrete combined section 4. It also avoids the need to use ultra-thick steel plates in extra-large span steel main beams.

[0067] The steel joints are cast in the concrete structure and their shapes match those of the steel box girders.

[0068] Furthermore, the abutment 2 comprises a box-type concrete structure, and a plurality of vertical CFRP anchor rods 14 are arranged at the bottom of the abutment 2 .

[0069] CFRP anchor rod 14 refers to carbon fiber reinforced composite anchor rod. Abutment 2 uses a cavity box concrete structure. CFRP anchor rod 14 is installed by drilling holes in the foundation pit, and the holes are filled with ultra-high performance concrete (UHPC) bonding medium. While meeting the pull-out requirements of abutment 2, the base burial depth is greatly reduced, and the height of the abutment body is reduced, thereby effectively reducing the lateral earth pressure of abutment 2, improving its lateral anti-sliding safety factor, and greatly reducing the amount of concrete used in abutment 2 and the amount of foundation pit excavation; the rock anchor point is arranged close to the anchor point of the cable 12, and the vertical component of the cable 12 can be directly transmitted to the bedrock through the rock anchor cable. The force transmission path is simple and significantly improves the stress state of the concrete side wall of abutment 2; the rock anchor rod also serves as the vertical prestressed tendon of the abutment body, and the ground anchor abutment 2 itself also serves as a retaining wall, with outstanding comprehensive functions. Based on ultra-high performance concrete (UHPC) bonding medium and carbon fiber reinforced composite (CFRP) tendon anchor rods, a rock anchor-gravity combined lightweight ground anchor abutment 2 structural system with high anchoring efficiency and excellent durability is formed.

[0070] Furthermore, the span ratio of the concrete beam 3 to the steel-UHPC composite beam 5 is in the range of 0.18-0.21.

[0071] The mid-span deflection of the main beam and the lateral displacement of the top of tower 1 under live load indicate that when the side-to-mid-span ratio is in the range of 0.18-0.21, the overall stiffness of the structural system is in a relatively good state.

[0072] As the side-to-mid-span ratio increases, the length of the side-span self-anchor section concrete beam 3 becomes longer, and the positive and negative moments of the live load on the consolidation surface show an increasing trend, and the positive moment increase further. Correspondingly, the tensile stress at the lower edge of the section increases significantly. When the side-to-mid-span ratio is greater than 0.21, the tensile stress is close to 70-80% of 0.5 "fcu,k". At this time, only design solutions such as adding auxiliary piers and optimizing the section can be used to improve it. In addition, the maximum live load moment of the tower body of cable tower 1 shows a concave parabolic change trend, and reaches a minimum value near the side-to-mid-span ratio of 0.186. "fcu,k" represents the standard value of the compressive strength of concrete cube test blocks.

[0073] The span ratio of the concrete beam 3 to the steel-UHPC composite beam 5 is in the range of 0.18-0.205.

[0074] Furthermore, the damping and shock absorbing structure 11 is a speed locker.

[0075] The damping and shock absorbing structure 11 has speed locking and viscous damping functions and can be a speed locker.

[0076] The sliding support mechanism 9 includes a spherical bearing.

[0077] The large box girder 7 and the guide beam 10 are connected by a spherical bearing, which can provide shock absorption and buffering, and the connection is stable, so that the guide beam 10 and the large box girder 7 can slide relative to each other along the length direction of the bridge.

[0078] A construction method for a large-span ground-anchored composite beam cable-stayed bridge is used to construct the large-span ground-anchored composite beam cable-stayed bridge, comprising the following steps:

[0079] Step 1: constructing the cable tower 1, the ground-anchored abutment 2 and the concrete beam 3;

[0080] Step 2: construct the steel-concrete combined section 4 and install the inclined cables 12 simultaneously;

[0081] Step 3: hoist the steel-UHPC composite beam to the work station, complete the welding of the steel main beam of the steel-UHPC composite beam between the segments and the pouring of the UHPC wet joints, and simultaneously hang the inclined cable 12;

[0082] Step 4: Hoist the adaptive connection device to the work station, carry out the connection construction between the adaptive connection device and the steel-UHPC composite beam, and complete the docking of the bridge.

[0083] In the above scheme, in step 1, the cable tower 1 and the abutment 2 are constructed at the bridge sites on both sides, the pile foundation and the abutment are first built, and the cable tower 1 is constructed, and the concrete beam 3 is constructed on the abutment 2, which can be constructed simultaneously on both sides; in step 2, the steel-concrete combination section 4 is constructed at the inner end of the concrete beam 3 to prepare for the steel box structure connection of the steel-UHPC composite beam, and the inclined cable 12 is installed; in step 3, the steel-UHPC composite beam can be prefabricated, transported to the site for direct hoisting and installation, welding the steel-UHPC composite beam and installing the inclined cable 12, and pouring UHPC on the top surface of the steel-concrete combination section 4; in step 4, the adaptive connection device can be directly prefabricated and hoisted to the installation site in the center of the bridge, and the large box beam 7 is welded to the steel structure of the steel-UHPC composite beam, and the concrete structure of the bridge deck is poured to complete the docking of the bridge. The steel main beam of the steel-UHPC composite beam refers to the internal steel box beam.

[0084] Furthermore, the concrete beam 3 is constructed using a full-bridge support, and the ground-anchored abutment is constructed using a flip-form method.

[0085] The full-span support construction and the flip-form construction method are used to ensure a stable structure. The support can be removed after the steel-UHPC composite beam is installed.

[0086] Furthermore, the steel-UHPC composite beams and the adaptive connection devices are prefabricated parts.

[0087] Prefabricated steel-UHPC composite beams and adaptive connection devices can reduce the construction workload and cycle on site.

[0088] The steel-UHPC composite beams and adaptive connection devices are assembled and the UHPC is poured in advance at the general assembly plant.

[0089] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A large-span ground-anchored composite beam cable-stayed bridge, characterized in that: It includes cable towers located on both sides of the cable-stayed bridge and ground-anchored abutments located outside the cable towers, concrete beams are respectively arranged on the inner sides of the two abutments, steel-concrete combined sections are respectively arranged on the inner ends of the two concrete beams, steel-UHPC composite beams are respectively connected to the inner ends of the two steel-concrete combined sections, and an adaptive connection device is arranged between the inner ends of the steel-UHPC composite beams; the adaptive connection device includes two large box beams respectively fixedly connected to the steel-UHPC composite beams, a plurality of box chambers are arranged in the middle of the large box beams along the length direction of the bridge, a sliding support mechanism is arranged on the inner periphery of the box chamber, the sliding support mechanism is connected to a guide beam, and a damping shock absorbing structure and an expansion joint are arranged between the two large box beams; a plurality of cables connected to the cable towers are respectively arranged on the abutments, concrete beams, and steel-UHPC composite beams; The two ends of the guide beam are provided with limited position adjustment structures; The limit adjustment structure includes an adjustment screw, one end of which is connected to the steel-UHPC composite beam or the large box beam, and the other end of which is used to connect to the guide beam; during normal operation, the guide beam is connected to the adjustment screw on one side; The damping shock absorbing structure is a speed locker.

2. The long-span ground-anchored composite beam cable-stayed bridge according to claim 1, characterized in that: The steel-UHPC composite beam comprises a steel box beam and a UHPC bridge deck layer, the steel-concrete combined section comprises a steel joint, and the steel box beam and the steel joint are welded.

3. The long-span ground-anchored composite beam cable-stayed bridge according to claim 1, characterized in that: The abutment comprises a box-type concrete structure, and a plurality of vertical CFRP anchor rods are arranged at the bottom of the abutment.

4. The long-span ground-anchored composite beam cable-stayed bridge according to claim 1, characterized in that: The span ratio of the concrete beam to the steel-UHPC composite beam is in the range of 0.18-0.

21.

5. A construction method for constructing a long-span ground-anchored composite beam cable-stayed bridge as claimed in any one of claims 1 to 4, characterized in that: The following steps are included: Step 1: constructing the cable tower, ground-anchored abutment and concrete beam; Step 2: Carry out the construction of the steel-concrete joint section and install the inclined cables simultaneously; Step 3: Hoist the steel-UHPC composite beam to the work station, complete the welding of the steel main beam of the steel-UHPC composite beam between segments and the pouring of the UHPC wet joints, and simultaneously hang the inclined cables; Step 4: Hoist the adaptive connection device to the work station, carry out the connection construction between the adaptive connection device and the steel-UHPC composite beam, and complete the docking of the bridge.

6. The construction method of a large-span ground-anchored composite beam cable-stayed bridge according to claim 5, characterized in that: The concrete beams are constructed using full-bridge supports, and the ground-anchored abutments are constructed using the flip-form method.

7. The construction method of a large-span ground-anchored composite beam cable-stayed bridge according to claim 5, characterized in that: The steel-UHPC composite beams and adaptive connection devices are prefabricated.

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