Door type tower cable-stayed bridge suspension cable stiffening extension structure and construction method

Abstract

The invention relates to the technical field of bridge engineering, in particular to a portal tower cable-stayed bridge suspension cable stiffening extension structure and a construction method. Comprising an existing cable-stayed bridge generally adopting a double-tower three-span type, the two transverse sides of an existing stiffening beam are directly widened and expanded, and the expanded part is suspended on a newly-added main cable through newly-added slings. The newly-added main cable is vertically supported on the bridge tower with the expanded cross section, and the newly-added anchorage is arranged on the side span for anchoring. The newly-added main cable is located on the outer side of the cable face of the existing stay cable, forms a certain inclination angle with the vertical face and is a space main cable. Namely, the distance between the newly-added main cable and the center line of the bridge axis is gradually increased from the tower top to the midspan, and the newly-added sling is inclined transversely. The existing cable-stayed bridge, the newly-added space main cable and the sling form an expanded cable-stayed-suspended cable cooperation system. The body structure of the cable-stayed bridge is fully utilized, the bridge deck system of the existing cable-stayed bridge can be widened through the expanded cooperation system according to needs, land is effectively saved, and cable-stayed bridge widening and expanding in engineering significance are achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of bridge engineering, in particular to a door-shaped tower cable-stayed bridge suspension stiffening expansion structure and a construction method. BACKGROUND

[0002] With the development of productivity, the living standards of the people and the per capita car ownership are constantly improving. Some early built highways are increasingly saturated in traffic, and it is urgently needed to improve the traffic capacity, improve the quality and efficiency, and save resources through reconstruction and expansion. Among them, the bridge is the key and difficult point in reconstruction and expansion, especially large-scale bridges such as cable-stayed bridges. Expanding the existing cable-stayed bridge in situ to increase the number of lanes can make full use of the existing cable-stayed bridge structure and effectively save land, which is the most economical and environmentally friendly way of reconstruction and expansion.

[0003] The stiffening beam body of the deck system of the cable-stayed bridge can be widened; the bridge tower is mainly a compression structure, and the settlement during the operation period has been stabilized, and has a certain overload capacity; but the bearing component cable, generally uses a finished cable, and is limited by the matching anchor head and anchoring system, so the cross section cannot be increased; therefore, it is difficult to directly expand the cable-stayed bridge.

[0004] The cable-stayed bridge with expansion demand is mostly realized by building a new cable-stayed bridge beside the existing cable-stayed bridge in engineering practice, but due to the limitation of navigation, flood control, bridge location planning and other factors, the new bridge location is either far away from the existing bridge location, or the route between the new project and the existing bridge connection line is large in influence range, the engineering route is generally smooth, and the investment is large; or the new project is greatly increased in span relative to the existing engineering bridge, the landscape coordination is poor, and the investment is huge. SUMMARY

[0005] In view of one or more deficiencies of the prior art, the present application provides a door-shaped tower cable-stayed bridge suspension stiffening expansion structure and a construction method, which expands the existing cable-stayed bridge in situ to increase the number of lanes, and the constant live load of the new lane is borne by the two new main cables, which makes full use of the existing cable-stayed bridge structure, is simple and compact, effectively saves land, and improves the material utilization rate, which is beneficial to energy saving and emission reduction.

[0006] In order to achieve the above purpose, the present application adopts one or more of the following technical solutions: In a first aspect, a door-shaped tower cable-stayed bridge suspension stiffening expansion structure is provided, comprising an existing cable-stayed bridge: an existing bridge tower and a stiffening beam divided into three spans by the bridge tower, a plurality of existing cable-stayed cables are arranged on both sides of the existing bridge tower along the length direction of the existing stiffening beam, the bottom of the existing cable-stayed cable is connected with the existing stiffening beam, and the top is connected with the existing bridge tower. The two sides of the existing full-bridge stiffening beam in the width direction are respectively provided with expanded stiffening beams for widening to increase the width and number of lanes; the two sides of the far-bridge-axis center line of the bridge tower are respectively provided with new space main cables, which are located outside the existing cable plane and form a cable-stayed-suspension combined system with a certain inclination angle with the vertical plane; the new space main cables are connected with the expanded edge-span stiffening beams by new hangers; the weight of the expanded stiffening beams and the operating load of the new lanes are borne by the new space main cables.

[0007] The tower top of the new space main cable is supported on the bridge tower by a new main cable saddle, and transmits vertical pressure to the bridge tower; the side span (outside the bridge tower) transmits the main cable tension to the new anchorage foundation through a spreader saddle and an anchoring system. To adapt to the vertical pressure transmitted by the new space main cable to the bridge tower, the cross section of the bridge tower is expanded in the longitudinal bridge direction and the lateral outside.

[0008] Preferably, the tower top of the new space main cable is located at the central cross section of the expanded bridge tower column, and the anchoring device of the expanded stiffening beam at the far-bridge-axis center line of the expanded lane is connected with the new hanger at the midspan of the new space main cable; that is, the lateral distance between the lowest point of the new space main cable at the midspan and the bridge axis is greater than the lateral distance between the highest point of the tower top and the bridge axis, and the plane of the new space main cable forms a certain angle with the vertical plane; the new space main cable is a space main cable. The inclination angle between the new space main cable and the vertical plane is related to the distance between the anchorage point on the beam of the new hanger and the bridge axis center line, the lateral distance between the new space main cable at the central point of the tower top column of the expanded bridge tower and the bridge axis center line, the height difference between the lowest point of the new space main cable at the midspan and the tower top of the bridge tower, and the cable force of the new hanger. The angle between the new space main cable and the vertical plane can be in the range of 1º to 17.5º; but to avoid the oblique hanger corresponding to the space cable from occupying the lane space, the angle range can generally be 1º to 5º.

[0009] As a further implementation manner, the lower end anchorage point of the new hanger corresponding to the new space main cable is located outside the expanded stiffening beam (away from the bridge axis center line side), and is fixed in the lateral distance from the bridge axis center line; the upper end is connected with the new space main cable, and the lateral distance from the bridge axis center line gradually increases from the tower top to the midspan, and is smaller than the distance from the anchorage point on the beam to the bridge axis center line, that is, the new hanger is laterally inclined and longitudinally vertically arranged. The anchorage points on the beam of the new hanger and the anchorage points on the beam of the existing cable-stayed cable are longitudinally arranged in an interval alternation manner, and the new hanger bears the dead and live loads of the expanded part of the stiffening beam, so as to control the cable force of the existing cable-stayed cable not to increase after the expansion of the stiffening beam is completed.

[0010] As a further implementation manner, the existing bridge tower is a gate tower or a column tower, that is, the lateral slope of the bridge tower is not large to adapt to the vertical pressure of the newly added space cable transmission; the expanded tower column is achieved by increasing the cross-sectional size outside the longitudinal and lateral directions of the existing bridge tower to improve the carrying capacity of the existing bridge tower; the existing bridge tower is a concrete bridge tower, and the expanded bridge tower is connected with the existing bridge tower as a whole by embedding steel bars in the existing bridge tower; the existing bridge tower is a steel structure bridge tower, and the expanded bridge tower is connected with the existing bridge tower as a whole by welding or bolt connection to bear force together.

[0011] As a further implementation manner, the shape of the saddle groove of the main cable saddle at the top of the expanded bridge tower is adapted to the line type of the newly added space main cable, arranged in a diagonal direction, and the diagonal angle is the same as the inclination angle of the newly added space main cable.

[0012] As a further implementation manner, in the cable-stayed-cable suspension combined system formed by expansion, the existing cable, the newly added space main cable and the main cable sling are arranged transversely symmetrically relative to the bridge axis.

[0013] As a further implementation manner, the cable saddle and anchoring system and anchorage foundation on the side span side (far from the bridge tower side) of the newly added space cable are located outside the transverse direction of the side span expansion stiffening beam; the left and right anchorage foundations can be independently arranged, or can be connected as a whole under the side span stiffening beam according to needs.

[0014] As a further implementation manner, since the existing bridge tower is relatively high compared with the general suspension bridge tower, in order to realize uniform stiffness of the existing cable support and the main cable sling support, the vertical span ratio of the newly added space main cable is 1 / 10-1 / 12.

[0015] On the other hand, a gate tower cable-stayed bridge suspension stiffening expansion construction method is provided, comprising the following steps: Erecting a newly added space main cable, specifically: Installing a main cable saddle at the top of the expanded bridge tower, installing a catwalk for the newly added space main cable, and erecting the newly added space main cable; after the erection is completed, the midspan of the newly added space main cable presents a planar main cable (the distance between the tower top and the midspan point is equal to the distance from the transverse center line of the bridge axis) under the action of self weight; A plurality of cross braces are used between the midspans of the two newly added space main cables, and the two newly added space main cables are pried apart by gradually adding sections and jacking to achieve the state of the space cable after expansion into a bridge; the newly added sling is installed according to the set distance, and the newly added sling is not tensioned at this time; Constructing an expanded stiffening beam, specifically: The expansion part of the stiffening beam on both sides is divided into longitudinal sections, and the existing expanded beam section is transported into place by on-beam transportation.

[0016] The two groups of separated self-walking cable load cranes supported on the two newly added space main cables symmetrically hoist, install and position the beam segments from the bridge towers to the midspan (the central side of the two bridge towers), newly add the hoisting cable tensioning, until the midspan closure position, push the hoisted expansion beam segments to the two sides at the midspan closure position, install the midspan closure expansion beam segments after the pushing, complete the midspan closure, and obtain the expansion stiffening beam of the midspan section. The longitudinal beam segments between the two sides of the expansion section of the midspan stiffening beam and the existing stiffening beam are temporarily connected.

[0017] The two groups of separated self-walking cable load cranes supported on the two newly added space main cables symmetrically hoist, install and position the beam segments from the bridge towers to the midspan (the central side of the two bridge towers), newly add the hoisting cable tensioning, until the midspan closure position, push the hoisted expansion beam segments to the two sides at the midspan closure position, install the midspan closure expansion beam segments after the pushing, complete the midspan closure, and obtain the expansion stiffening beam of the midspan section. The longitudinal beam segments between the two sides of the expansion section of the midspan stiffening beam and the existing stiffening beam are temporarily connected.

[0018] After the expansion sections of the side span and the midspan stiffening beams are closed, the newly added hoisting cable tension is fine-tuned, the elevation of the interface between the expansion section of the stiffening beam and the existing stiffening beam is fine-tuned, and the temporary connection is adjusted to permanent connection such as welding or high-strength bolt, so that the newly added space main cable and the expansion section of the stiffening beam reach the bridge alignment.

[0019] The bridge is in operation, specifically: The newly added space main cable is wound and protected, then the catwalk is removed, the closing project of the newly added cable saddle and anchoring system and the newly added main cable saddle is completed, and finally the acceptance and traffic operation are carried out.

[0020] As a further implementation manner, before the newly added space main cable is erected, the expansion tower column is constructed on the lateral outside of the existing bridge tower, specifically: The bored pile foundation is newly added on the lateral outside of the existing bridge tower foundation, the newly added pile top is poured with the newly added pile cap, the newly added pile cap and the existing pile cap are connected into a whole through the embedded steel bars, the bored pile-pile cap foundation is formed by the newly added pile and the existing pile, and the tower column cross section of the existing bridge tower is expanded on the newly added bored pile-pile cap foundation along the longitudinal and lateral outside, to form the expansion tower column.

[0021] As a further implementation manner, the newly added main cable saddle corresponding to the newly added space main cable at the tower top is kept a certain distance from the lateral position of the existing cable-stayed cable; preferably, the distance between the main cable saddle and the existing cable-stayed cable is not less than one time of the diameter of the newly added space main cable, so as to avoid mutual interference in the cable forming process of the newly added space main cable.

[0022] By adopting the above technical scheme, the application has the following beneficial effects: 1. The application is used for bridge expansion, through the cooperation of the expansion stiffening beam and the newly added space main cable, two newly added space main cables are located outside the existing cable-stayed cable plane, on the one hand, the body structure of the cable-stayed bridge is fully utilized, the number and width of the driving lane are increased, on the other hand, the newly added space main cable and the existing cable-stayed cable form a cable-stayed and suspension combined system, the weight of the expansion stiffening beam and the running load of the newly added driving lane are borne by the newly added space main cable, the carrying capacity of the cable-stayed bridge is greatly improved, the bridge deck system of the existing cable-stayed bridge can be widened according to the need, the structural performance of the bridge expansion structure is ensured, the cable-stayed bridge widening is realized, which is beneficial to reducing the engineering investment and improving the economic benefit.

[0023] 2. The application is directly widened and expanded on both sides of the existing stiffening beam of the cable-stayed bridge, which is smoothly connected with the connection line and occupies less land, and has high economic efficiency; at the same time, the corresponding route index is high, the driving comfort can be improved, and the modern transportation demand can be met.

[0024] 3. In the application, the newly added space main cable and the existing stiffening beam are connected through the obliquely added sling, the beam upper anchor points of the newly added sling and the beam upper anchor points of the existing cable-stayed cable are longitudinally arranged in an interval alternation, and are transversely located outside the expansion stiffening beam; the sling anchor points and the existing cable-stayed cable anchor points are kept at a certain distance in the longitudinal and transverse directions, the existing cable-stayed cable and the newly added sling anchoring device of the stiffening beam are uniformly arranged, the stress is smooth, and stress concentration at the anchoring device is avoided.

[0025] 4. In the application, the highest point of the newly added main cable tower top is located at the tower top of the bridge tower, the stiffening beam anchoring device corresponding to the newly added sling is located outside the expansion stiffening beam, under the action of the sling transverse force, the newly added main cable is a space cable, that is, the transverse distance between the lowest point of the newly added main cable in the span and the bridge axis is greater than the transverse distance between the highest point of the tower top and the bridge axis, the newly added main cable forms a certain angle with the vertical plane, and is a space cable; the space cable fully utilizes the existing bridge tower, the bridge tower can be expanded in situ to bear the vertical pressure transmitted by the space cable. The expansion tower column and the foundation occupy a small area, and the land is saved.

[0026] 5. In the application, the existing stiffening beam can be widened and expanded by using a box girder, a truss girder or a plate girder, and only the cable-stayed cable or the main cable sling support is arranged on the same cross section of the stiffening beam after widening and expansion, so that the force transmission can be ensured. The constant live load of the expansion stiffening beam part is borne by the newly added sling, the cable force of the existing cable-stayed cable can be controlled to be less than or equal to the cable force before expansion, the existing cable-stayed cable can be fully utilized, and the cable-stayed cable is avoided to be replaced.

[0027] 6. The newly added space main cable and the stay cable on both sides of the tower in the present application are transversely symmetrically arranged relative to the bridge axis, and the main cable saddle of the newly added space main cable maintains a certain distance from the existing stay cable, so that mutual interference during the main cable forming process can be avoided, and a stay-cable-suspender combined system is formed by the newly added space main cable and the existing stay cable. BRIEF DESCRIPTION OF DRAWINGS

[0028] The accompanying drawings, which form a part of this specification, are included to provide a further understanding of the application and are incorporated in and constitute a part of this specification. The embodiments of these drawings are set to explain the present application, and do not constitute an improper limitation to the present application.

[0029] Figure 1 The plan and elevation schematic diagram of the existing cable-stayed bridge before expansion and the suspension-stiffened expansion structure after expansion in one or more embodiments of the present application; Figure 2 The schematic diagram of the arrangement of the newly added main cable saddle at the top of the tower and the existing stay cable in one or more embodiments of the present application; Figure 3 The three-dimensional schematic diagram of the suspension-stiffened expansion structure 1 / 2 span in one or more embodiments of the present application Figure 1 ; Figure 4 The three-dimensional schematic diagram of the suspension-stiffened expansion structure 1 / 2 span in one or more embodiments of the present application Figure 2 ; Figure 5 The plan view schematic diagram of the suspension-stiffened expansion structure 1 / 2 span in one or more embodiments of the present application; Figure 6 The cross-sectional schematic diagram of the suspension-stiffened expansion structure using the newly added suspender support in one or more embodiments of the present application (the section has no existing stay cable anchor point); Figure 7 The cross-sectional schematic diagram of the suspension-stiffened expansion structure using the existing stay cable support in one or more embodiments of the present application (the section has no newly added suspender anchor point); Figure 8 The construction process schematic in embodiment two of the present application Figure 1 ; Figure 9 The construction process schematic in embodiment two of the present application Figure 2 ; In the figure: 1, newly added space main cable; 2, newly added suspender; 3, existing stay cable; 4, existing stiffened beam; 5, stiffened beam widened part; 6, existing tower; 7, newly added part of the tower column section; 8, existing tower foundation; 9, expanded part of the tower foundation; 10, newly added saddle at the top of the tower; 11, tower-beam connecting device; 12, existing cable-stayed bridge side span pier; 13, newly added spreader saddle and anchoring system; 14, newly added anchorage foundation. DETAILED DESCRIPTION

[0030] It should be noted that the following detailed description is illustrative and is intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meaning as commonly understood by those skilled in the art to which the present invention belongs.

[0031] It should be noted that the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work are within the scope of protection of the present invention.

[0032] Example 1 In a typical embodiment of the present application, a cable-stayed bridge with a portal tower and a cable-stiffened expansion structure is provided. Figures 1-4 As shown, there are shown a newly added spatial main cable 1, a newly added suspender 2, an existing cable-stayed cable 3, an existing stiffening beam 4, a widened part of the stiffening beam 5, an existing bridge tower 6, a newly added part of the tower column section 7, an existing bridge tower foundation 8, an expanded part of the bridge tower foundation 9, a newly added cable saddle 10 on the tower top, a tower-beam connecting device 11, an existing cable-stayed bridge side span pier 12, a newly added loose cable saddle and anchoring system 13 and a newly added anchoring foundation 14.

[0033] The existing portal-type cable-stayed bridge comprises an existing stiffening beam 4 and an existing bridge tower 6. Along the length direction of the existing stiffening beam 4, a plurality of existing inclined cables 3 are respectively provided on both sides of the existing bridge tower 6. The bottom of the existing inclined cables 3 is connected to the existing stiffening beam 4, and the top is connected to the existing bridge tower 6. The existing stiffening beam 4 is widened by installing expanded stiffening beams on both sides in the width direction to increase the width and number of lanes; new spatial main cables 1 are installed on both sides of the existing bridge tower 6 in the lateral direction, and the new spatial main cables 1 are located on the outside of the existing inclined cables 3 to form an inclined-stayed-cable combined system; the new spatial main cables 1 are connected to the widened part 5 of the stiffening beam by new slings 2; the weight of the widened part 5 of the stiffening beam and the operational load of the new lane are borne by the new spatial main cables 1.

[0034] Specifically, the existing cable-stayed bridge widening technology usually adjusts the bridge deck arrangement to increase the driving lane or pedestrian lane while maintaining the weight of the bridge deck system unchanged. However, because the bearing structure of the cable-stayed cable cannot be increased, the existing widening can only increase the bridge deck width to a very limited extent, and cannot realize the true expansion of the bridge. The suspension stiffening expansion structure provided in the embodiment adds two new space main cables 1 on the transverse sides of the pylons of the cable-stayed bridge, improves the carrying capacity of the existing cable-stayed bridge, and can cooperate with the widening of the bridge deck of the existing stiffening beam 4 to effectively expand the number and width of the driving lanes of the bridge deck arrangement and ensure safe carrying capacity, realizing the expansion of the original cable-stayed bridge in the engineering sense.

[0035] To fully utilize the pressure bearing capacity of the pylons of the original cable-stayed bridge, the bending moment of the pylon caused by the main cable force needs to be controlled, and the eccentricity between the main cable pressure and the axis of the pylon needs to be reduced. Only for cable-stayed bridges with small inclination of the door-shaped and single-column-shaped pylons.

[0036] As shown in Figure 1 , the existing cable-stayed bridge structure includes an existing stiffening beam 4, an existing cable 3, and an existing pylon 6. The existing stiffening beam 4 has several driving lanes on its top surface, and the existing pylon 6 is a door-shaped tower with a small tower column slope close to vertical, generally with two pylons. The existing stiffening beam 4 transmits the dead load and other live loads to the existing pylon 6 through the existing cable 3. Along the length direction of the existing stiffening beam 4, the top end of the existing cable 3 is connected to the existing pylon 6, and the bottom end is connected to the existing stiffening beam 4.

[0037] As shown in Figure 1 , the transverse sides of the existing stiffening beam 4 are respectively provided with a stiffening beam widening part 5 to widen the bridge deck and increase the number and width of the driving lanes on the bridge deck. The existing stiffening beam 4 and the stiffening beam widening part 5 can be connected as a whole by implanting steel bars, welding, or high-strength bolt connection according to different materials to bear the load together. The transverse sides of the expanded pylon 6, 7 are respectively provided with a new space main cable 1, and the two new space main cables 1 are located outside the cable plane of the existing cable 3 and are connected to the stiffening beam widening part 5 on both sides of the bridge deck through a new suspension cable 2 to bear the dead load and driving load of the stiffening beam widening part 5.

[0038] As shown in Figure 1 , Figure 3 , Figure 4 , the new space main cable 1, the new suspension cable 2, and the existing cable 3 form a cable-suspension cooperative system to bear the dead load and live load of the expanded stiffening beam.

[0039] Specifically, in combination with Figure 2 , Figure 3 , Figure 4As shown, the newly added spatial main cable 1 is supported on the pylon by a new saddle 10 at the tower top, changing the main cable's alignment. The side span main cable transmits its tension to the newly added anchorage foundation 14 via a new loose saddle and anchoring system 13. To absorb the vertical pressure from the tower top transmitted by the newly added spatial cable, the existing pylon 6 was expanded. Extension tower columns 7 are installed on the outer sides of the pylons on either side. These extension tower columns 7 are connected to the existing pylon 6 through embedded rebar or welding, forming a single unit to support the load.

[0040] like Figure 3 As shown in the figure, in order to avoid collision between the newly added spatial main cable 1 and the existing inclined cable 3 under strong wind after the expansion is completed, the newly added spatial main cable 1 adopts a spatial cable, that is, the lateral distance between the center of the newly added spatial main cable 1 and the center line of the bridge axis gradually increases from the tower top to the mid-span, and the lateral distance between the mid-span point and the bridge axis is the largest; the lateral distance between the mid-span point of the newly added spatial main cable 1 and the center line of the bridge axis is greater than the lateral distance between the tower top and the center line of the bridge axis, that is, the newly added spatial main cable 1 forms a certain angle with the vertical plane, and the inclination angle of the newly added spatial main cable 1 and the vertical plane is determined by the coordinates of the mid-span of the newly added spatial main cable 1.

[0041] like Figure 2 As shown, the tower apex of the newly added spatial main cable 1 (corresponding to the position of the main saddle) maintains a certain distance from the transverse direction of the existing inclined cable 3, which is controlled according to 1 times the diameter D of the newly added spatial main cable 1 to ensure the construction space during the cabling process of the newly added spatial main cable 1; the saddle groove of the newly added saddle 10 on the tower top corresponding to the newly added spatial main cable 1 is arranged obliquely, and the oblique inclination angle between the saddle groove axis of the newly added saddle 10 on the tower top and the vertical plane is the same as the oblique inclination angle between the spatial surface where the newly added spatial main cable 1 is located and the vertical plane.

[0042] like Figure 1 , Figure 3 , Figure 4 As shown, each newly added spatial main cable 1 includes a mid-span main cable located between adjacent bridge towers and a side-span main cable located outside the bridge towers; the mid-span main cable is connected to the widened portion 5 of the mid-span (between the bridge towers) stiffening beam via a newly added sling 2, and the side-span main cable is connected to the side-span stiffening beam (on the far side of the bridge towers) via a newly added sling 2.

[0043] In this embodiment, since the existing bridge tower 6 is higher than that of a conventional suspension bridge, in order to achieve uniform stiffness of the existing inclined cable 3 support and the main cable suspender support, the vertical span ratio of the newly added spatial main cable 1 is controlled between 1 / 10 and 1 / 12.

[0044] like Figure 3 、 Figure 4 、 Figure 5As shown, after the expansion is completed, the new spatial main cable 1 is in a spatial cable shape in the bridge operation state, that is, the distance between the midspan of the new spatial main cable 1 and the bridge axis center line is greater than the distance between the tower top and the bridge axis center line. In the completed bridge state, the new spatial main cable 1 is in a spatial cable shape due to the transverse tension of the new suspension cable 2, that is, the spatial cable shape of the new spatial main cable 1 is formed by the self-weight of the main cable and the tension of the new suspension cable 2. The new suspension cable 2 is inclined on the cross section of the existing stiffening beam 4, and has a certain angle with the vertical plane, that is, the distance between the upper end of the new suspension cable 2 and the cable clamp connected with the new spatial main cable 1 and the bridge axis center line is less than the distance between the lower end of the new suspension cable 2 and the anchoring device connected with the stiffening beam widened portion 5 and the bridge axis center line. The anchoring head at the lower end of the new suspension cable 2 is connected with the stiffening beam widened portion 5 by using anchoring devices such as anchoring head pressure type or pin connection type; the anchoring devices such as anchoring head pressure type or pin connection type are integrally manufactured and installed with the stiffening beam widened portion 5, and are integrally formed.

[0045] Specifically, as shown in Figure 3 , Figure 4 The main cable suspension cable and the existing cable are longitudinally arranged in an interval and alternately arranged, so that the vertical load borne by each group of cable and main cable suspension cable is basically the same, thereby controlling the cable force of the existing cable to be less than or equal to the cable force before the widening is completed, so as to ensure the stability and durability of the expansion structure.

[0046] Specifically, as shown in Figure 1 , Figure 3 , Figure 4 As shown, the new spatial main cable 1 on the transverse two sides of the bridge tower is arranged transversely symmetrically relative to the bridge axis, the new spatial main cable 1 on each side is connected with the expansion stiffening beam through the new main cable suspension cable, the transverse distance between the midspan point and the bridge axis is greater than the transverse distance between the tower top point and the bridge axis, that is, the new spatial main cable 1 has a certain angle with the vertical plane, and the new spatial main cable 1 forms a cable-stayed-suspension combined system with the existing cable.

[0047] As shown in Figure 1 , 3 , 4, 5, the cable saddle and anchoring system 13 and anchorage foundation 14 on the side span side (far from the bridge tower side) of the new spatial main cable 1 are located on the transverse outer side of the whole formed by the existing stiffening beam 4 and the stiffening beam widened portion 5 on the side span side; so as to avoid the interference between the new spatial main cable 1 and the new suspension cable 2 and the stiffening beam widened portion 5 on the side span side. The new anchorage foundation 14 located on the left and right sides of the stiffening beam widened portion 5 on the side span side can be independently set, or can be connected into a whole under the stiffening beam 4 on the side span according to needs.

[0048] In the cable-stayed-suspension combined system formed in the embodiment, the cable, the new spatial main cable 1 and the main cable suspension cable are all arranged transversely symmetrically, and the angle between the new spatial main cable 1 and the vertical plane is controlled to be 1°-5°, which can ensure that the oblique main cable suspension cable at the midspan does not invade the driving space.

[0049] As shown in Figure 6 , Figure 7 , the stiffened beam 4 of the cable-stayed bridge can adopt a box girder, a truss girder or a plate girder, and the anchoring device is arranged on the transverse outer side of the stiffened beam widening part 5. As shown in Figure 1 , Figure 3 , Figure 4 , the upper end of the new hanging cable 2 is connected with the new space main cable 1, and the lower end is connected with the stiffened beam widening part 5 through the anchoring device, that is, the stiffened beam widening part 5 is suspended and supported on the new space main cable 1 through the new hanging cable 2; the new traffic lane is separated from the existing traffic lane by the existing anti-collision guardrail and the existing stay cable 3. After the bridge deck widening is completed on the basis of the existing stiffened beam 4, only the main cable suspension or the stay cable is supported on the same cross section of the stiffened beam, which can ensure that the stay cable, the main cable suspension and the stiffened beam are clearly stressed.

[0050] Embodiment two In another typical embodiment of the present application, a construction method for expanding and reinforcing a cable-stayed bridge suspension is provided based on the door-type tower cable-stayed bridge suspension reinforcing and expanding structure of embodiment one, which comprises the following steps (as shown in Figure 8 , Figure 9 ): The new space main cable 1 is erected, specifically: The new main cable saddle is installed at the top of the expanded bridge tower, the main cable traction cable is erected, the catwalk is installed, the main cable strand is erected, the cable is tightened and the cable clamp is installed; in the self-weight state, the midspan of the new space main cable 1 presents as a planar main cable, that is, the tower top and the transverse position of the midspan of the new space main cable 1 are the same.

[0051] The multi-channel cross brace is adopted, and the new space main cable 1 is expanded to the bridge space cable state through adding joints and jacking, and the main cable suspension is installed; wherein the cross brace adopts a walking type bracing device with variable span within a certain range; The stiffened beam widening expansion part is installed, specifically: The midspan expansion girder section is symmetrically hoisted from the existing bridge tower 6 to the midspan, as shown in Figure 8 , Figure 9 , the stiffened beam widening part 5 is longitudinally segmented, the beam transportation machinery can be used to transport the stiffened beam widening part 5 from the bridge deck of the existing stiffened beam 4 to the installation position; then the separated self-walking cable load crane supported on the new space main cable 1 is used for hoisting and positioning, and then temporarily connected with the existing stiffened beam 4 girder section. The separated self-walking cable load crane moves from the side of the expanded bridge tower (including 6 and 7) to the midspan, symmetrically hoists the stiffened beam widening part 5, and temporarily connects the stiffened beam widening part 5 longitudinally and the existing stiffened beam 4; after the stiffened beam widening part 5 girder section is hoisted, connected and positioned, the new hanging cable 2 corresponding to the girder section is tensioned; The separate self-walking cable-mounted crane supported on the newly-added space main cable 1 gradually moves from the side of the tower to the side of the midspan, continues to hoist the stiffening beam widening part 5, and until the midspan closure beam section; the completed widened beam sections on both sides of the closure section are jacked to the side of the tower, then the stiffening beam widening part 5 of the midspan closure section is hoisted and installed, and is temporarily connected with the existing stiffening beam 4 and the stiffening beam widening part 5 of the midspan closure section longitudinally, the midspan closure is completed, and the expanded stiffening beam of the midspan section is obtained; The stiffening beam widening part 5 is sequentially hoisted from the outer end of the existing cable-stayed bridge side span to the direction of the existing tower 6, until the side span closure position at the existing tower 6, and the expanded stiffening beam of the side span section is obtained. The midspan expanded beam section and the side span expanded beam section on both sides of the side span closure are respectively jacked to both sides, the side span closure section is installed, the side span closure section is temporarily connected with the existing stiffening beam 4 and the adjacent expanded beam section, the side span closure is completed, and the expanded stiffening beam is obtained.

[0052] In order to bear the vertical axial pressure transmitted by the newly-added space main cable 1 to the tower, before the newly-added space main cable 1 is erected, the tower column cross section is expanded on the lateral outer side of the existing tower 6, specifically: a bored pile foundation is newly added on the lateral outer side of the foundation of the existing tower 6; a new pile cap is cast on the top of the newly-added bored pile, and the new pile cap and the existing pile cap are connected into a whole through the embedded steel bars in the existing pile cap, forming a new bored pile-pile cap foundation; the tower column cross section of the existing tower 6 is expanded along the lateral outer side on the new bored pile-pile cap foundation, forming an expanded tower column. The expanded tower column on the lateral outer side of the cross section of the existing tower 6 can bear the vertical force of the newly-added bridge deck formed by the expanded stiffening beam and the newly-added space main cable 1, and the expanded tower column and foundation occupy a small area, which can save land.

[0053] In this embodiment, the detailed construction steps of the cable-stayed suspension stiffening expansion construction method of the cable-stayed bridge are as follows: (1) Expanded tower foundation: bored pile foundations are newly added on the lateral outer side of the foundation pile cap of the existing tower 6; a new pile cap is cast on the top of the newly-added bored pile, forming a bored pile-pile cap foundation; the new pile cap and the foundation pile cap of the existing tower 6 are connected into a whole through the embedded steel bars in the foundation pile cap of the existing tower 6.

[0054] (2) Construction of expanded tower column: the tower column cross section of the existing tower is expanded to the longitudinal and lateral outer side (far from the bridge axis center line side) on the newly-added bored pile-pile cap foundation. The new and old cross sections of the tower are connected into a whole through the embedded steel bars in the existing concrete tower, or are connected into a whole with the existing steel structure tower through welding and high-strength bolt connection, obtaining the expanded tower column after construction. The main cable saddle corresponding to the newly-added space main cable 1 is installed on the top of the expanded tower column.

[0055] (3) Construction of main cable anchoring system: expand the cross section of the existing tower 6, set anchor foundation on the side of the side span of the cable-stayed bridge, install the spreader saddle and the main cable anchoring system.

[0056] The above construction sections can operate normally under the premise of taking relevant safety measures; the following construction sections must be closed for construction.

[0057] (5) Preliminary erection of new space main cable 1: erect main cable traction cable, install catwalk, erect main cable strand, tighten cable and install cable clamp; change catwalk to crane. The new space main cable 1 only bears self-weight in this stage, and the midspan of the new space main cable 1 is a plane main cable, i.e. the top of the main cable tower and the transverse position of the midspan are the same.

[0058] (6) Preliminary construction of expanded stiffening beam of midspan section: two groups of separated self-walking cable load cranes supported on two new space main cables 1 symmetrically hoist, install and position the beam sections from the bridge tower to the midspan (central side of the two bridge towers), tension the new stay cable 2, and then push the two sides of the closure section, the beam sections that have been widened, to the bridge tower side with jacks, and then install the midspan closure expanded beam section to complete the midspan closure to obtain the expanded stiffening beam of the midspan section. The longitudinal beam sections of the widened expansion sections on both sides of the midspan stiffening beam and the beam sections of the existing stiffening beam 4 are temporarily connected.

[0059] (7) Preliminary construction of expanded stiffening beam of side span section: two groups of separated self-walking cable load cranes supported on two new space main cables 1 symmetrically hoist the side span expanded beam sections from the outer end of the side span (outer side of the bridge tower) to the existing bridge tower 6 direction in turn, until the side span closure position at the bridge tower; push the midspan expanded beam sections and the side span expanded beam sections on both sides of the side span closure to the two sides respectively, and then install the side span closure section to obtain the expanded stiffening beam of the side span section; the longitudinal beam sections of the widened expansion sections on both sides of the side span stiffening beam and the beam sections of the existing stiffening beam 4 are temporarily connected.

[0060] (8) Expanded stiffening beam erection is completed: after the closure of the expanded sections of the side span and midspan stiffening beams, the new stay cable 2 is fine-tuned to make the new space main cable 1 reach the bridge alignment; the elevations of the interface between the expanded sections of the stiffening beam and the existing stiffening beam 4 are fine-tuned, and the temporary connection is adjusted to permanent connection such as welding or high-strength bolt. (9) Bridge deck system construction; main cable winding, protection. Catwalk is removed, and the anchor and main cable saddle closure project is completed.

[0061] (10) Open to traffic.

[0062] In the above process, the newly added space main cable 1 is fixed at the main cable saddle at the top of the expanded bridge tower, and is kept a certain distance from the existing cable 3. Specifically, the distance between the main cable saddle and the existing cable 3 is not less than one diameter of the newly added space main cable 1, so as to avoid mutual interference during the cable forming process of the newly added space main cable 1.

[0063] It should be noted that the above examples are only used to illustrate the technical solutions of the present application, and are not limiting. Those skilled in the art should understand that the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A portal tower cable-stayed bridge suspension stiffening extension structure, characterized in that, The existing cable-stayed bridge includes an existing bridge tower and a stiffened beam divided into three spans by the bridge tower, a plurality of existing cables are arranged on both sides of the existing bridge tower along the length direction of the existing stiffened beam, the bottom of the existing cable is connected with the existing stiffened beam, and the top of the existing cable is connected with the existing bridge tower; The two sides of the existing stiffened beam in the width direction are respectively provided with expanded stiffened beams for widening to increase the width and the number of lanes; the two sides of the far-bridge-axis center line of the bridge tower are respectively provided with new space main cables, the new space main cables are located outside the plane of the existing cable and form a cable-suspension combined system with a certain inclination angle with the vertical plane; the new space main cables are connected with the expanded stiffened beams by using new hangers; the weight of the expanded stiffened beam and the running load of the new lane are borne by the new space main cables.

2. The portal tower cable-stayed bridge suspension stiffening extension structure according to claim 1, characterized in that, The new space main cable tower top is located in the central cross section of the expanded bridge tower column, and the anchoring device of the expanded stiffened beam located on the far-bridge-axis center line of the expanded lane is connected through the new hanger.

3. The portal tower cable-stayed bridge suspension stiffening extension structure according to claim 2, characterized in that, The lower end beam anchor point of the new hanger corresponding to the new space main cable is located outside the expanded stiffened beam, and the horizontal distance from the bridge-axis center line is fixed; the upper end is connected with the new space main cable, and the horizontal distance from the bridge-axis center line gradually increases from the tower top to the midspan, and is smaller than the distance from the beam anchor point to the bridge-axis center line, that is, the new hanger is horizontally inclined and vertically arranged.

4. The portal tower cable-stayed bridge suspension stiffening extension structure according to claim 3, characterized in that, The existing bridge tower is a portal tower or a column tower; or the existing bridge tower is a concrete bridge tower, and the expanded bridge tower is connected with the existing bridge tower to form a whole by implanting reinforcing steel bars in the existing bridge tower; or the existing bridge tower is a steel structure bridge tower, and the expanded bridge tower is connected with the existing bridge tower to form a whole by welding or bolt connection.

5. The portal tower cable-stayed bridge suspension stiffening extension structure according to claim 4, characterized in that, The saddle groove shape of the main cable saddle at the top of the expanded bridge tower is adapted to the line type of the new space main cable, is arranged obliquely, and the oblique angle is the same as the inclination angle of the new space main cable.

6. The portal tower cable-stayed bridge suspension stiffening extension structure according to claim 1, characterized in that, In the cable-suspension combined system formed by expansion, the existing cable, the new space main cable and the main cable hanger are horizontally symmetrically arranged relative to the bridge-axis.

7. The portal tower cable-stayed bridge suspension stiffening extension structure according to claim 6, characterized in that, The vertical-span ratio of the new space main cable is 1 / 10-1 / 12. 8.A portal tower cable-stayed bridge suspension stiffening expansion construction method based on the portal tower cable-stayed bridge suspension stiffening expansion structure according to any one of claims 1-7, comprising the following steps: erecting a new space main cable, specifically: installing a main cable saddle at the top of the expanded bridge tower, installing a catwalk for the new space main cable, and erecting the new space main cable; after the erection is completed, the new space main cable in the midspan presents a planar main cable under the action of self weight; using multiple cross braces between the midspans of the two new space main cables, gradually adding sections and jacking to separate the two new space main cables in the midspan, and reaching the space cable state after expansion; install new hangers at a set distance, at this time the new hangers are not tensioned; constructing an expanded stiffened beam, specifically: the widened expansion parts on both sides of the stiffened beam are divided into longitudinal sections, and the existing expanded beam sections are transported into place by using beam transportation; The two groups of separated self-walking cable-mounted cranes supported on the two newly added space main cables symmetrically hoist, install, and position the beam segments from the bridge tower to the midspan, newly add the hoisting cable tensioning, push the midspan expansion beam at the midspan closure position to the two sides, install the midspan closure expansion beam segment, complete the midspan closure, and obtain the expansion stiffening beam of the midspan segment; the temporary connection is adopted between the longitudinal beam segments of the widened expansion part on the two sides of the midspan stiffening beam and between the longitudinal beam segments of the widened expansion part and the existing stiffening beam segment; The two groups of separated self-walking cable-mounted cranes supported on the two newly added space main cables symmetrically hoist, install, and position the beam segments from the bridge tower to the midspan, newly add the hoisting cable tensioning, push the midspan expansion beam at the midspan closure position to the two sides, install the midspan closure expansion beam segment, complete the midspan closure, and obtain the expansion stiffening beam of the midspan segment; the temporary connection is adopted between the longitudinal beam segments of the widened expansion part on the two sides of the midspan stiffening beam and between the longitudinal beam segments of the widened expansion part and the existing stiffening beam segment; After the stiffening beam expansion part of the side span and the midspan is closed, the newly added hoisting cable tension is fine-tuned, so that the newly added space main cable reaches the bridge alignment; the elevation of the interface between the stiffening beam expansion part and the existing stiffening beam is fine-tuned, and the temporary connection is adjusted to permanent connection such as welding or high-strength bolt. Bridge operation, specifically: The newly added space main cable is wrapped with wire, protected, and then the catwalk is removed; the closure project of the newly added cable saddle and anchoring system and the newly added main cable saddle is completed; finally, acceptance and traffic operation are carried out.

9. The method of claim 8, wherein the method further comprises: providing a plurality of temporary towers on the existing bridge deck; and connecting the plurality of temporary towers to the plurality of temporary cables. The expansion tower column is constructed on the transverse outer side of the existing bridge tower, specifically: The bored pile foundation is newly added on the transverse outer side of the existing bridge tower foundation; the newly added pile cap is poured on the top of the newly added bored pile, and the newly added pile cap, the existing pile cap, the newly added bored pile, and the existing bored pile are connected into a whole through the embedded steel bars in the existing pile cap and the steel bars of the newly added pile cap, so as to form a bored pile-pile cap foundation; the tower column cross section of the existing bridge tower is expanded along the transverse outer side on the newly added bored pile-pile cap foundation, and the expansion tower column is formed.

10. The method of claim 9, wherein the method further comprises: The newly added space main cable corresponds to the newly added main cable saddle at the top of the tower, and the transverse position of the top of the tower is kept a certain distance from the transverse position of the existing cable; the distance between the main cable saddle and the existing cable is not less than twice the diameter of the newly added space main cable.

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