A wide-span, large-span hybrid beam, low-tower cable-stayed bridge system and its construction method

Abstract

The invention discloses a wide and large-span hybrid beam low-tower cable-stayed bridge system and its construction method and its construction method, including a hybrid beam composed of a concrete box beam and a corrugated web steel box-concrete composite beam arranged on both sides of the transverse bridge; the concrete box beam is located on both sides of the middle support and is cast as a whole with the bridge tower; the composite beam is located in the middle of the side span and the middle span; the concrete box beam and the composite beam are connected by a steel-concrete combination section; the steel-concrete combination section is formed by casting the combination section concrete in the corrugated web steel box; the hybrid beam is horizontally connected by a middle support concrete beam, a truss steel beam, an I-shaped steel beam and an end beam; a bridge deck is arranged on it; the hybrid beam is supported by a main pier and a transition pier; the hybrid beam low-tower cable-stayed bridge system has a reasonable design, is easy to construct, has a good use effect, and can be used for wide and large-span bridges. At the same time, the invention also discloses a matching construction method, including the steps of bridge tower construction, concrete box beam construction, composite beam construction and steel-concrete combination section construction, the construction method is complete, and the construction progress is fast.

Description

Technical Field

[0001] The present invention relates to the technical field of bridge structures, and in particular to a wide-span, large-span, hybrid-beam, low-tower cable-stayed bridge system and a construction method thereof. Background Art

[0002] The low-tower cable-stayed bridge, also known as a partial cable-stayed bridge, is a structural system between a continuous beam bridge and a cable-stayed bridge. Since it has the structural advantages of both continuous beam bridges and cable-stayed bridges, it has a wide range of applications.

[0003] The main beams of traditional low-tower cable-stayed bridges mostly use single-box single-chamber or multi-chamber concrete box sections. Although such sections can provide greater rigidity, they also have inevitable technical problems:

[0004] (1) For wide bridges, single-box multi-chamber sections are often used, which greatly increases the volume of concrete, causing the negative bending moment at the top of the main beam under the action of its own weight to increase, seriously affecting the bearing capacity of the main beam and making it very easy for the top surface of the main beam to crack.

[0005] (2) For large-span bridges, a concrete box section is used in the mid-span, which greatly increases the positive bending moment of the main beam in the mid-span and the negative bending moment on the pier top, making the bottom plate of the mid-span box beam and the top plate of the middle support box beam extremely easy to crack, seriously affecting the bearing capacity and performance of the main beam. At the same time, due to the increase in the bending moment of the main beam, a large number of prestressed steel bars and large-sized cables are required, resulting in unnecessary waste of materials, increasing the cost of the low-tower cable-stayed bridge, and affecting its economic performance.

[0006] (3) Due to the stress characteristics of single-box single-chamber or multi-chamber concrete box sections, the towers of low-tower cable-stayed bridges are mostly arranged in the central dividing strip and use a central cable surface. For wide-span bridges, due to the increase in the lateral width, the lateral stress of the main beam becomes more complex and the shear lag effect is obvious, resulting in a decrease in the stress performance of the main beam. At the same time, due to the limited location of the bridge tower, the structural form of the bridge tower is mostly a single-column tower, which is a single form and cannot meet higher landscape requirements.

[0007] (4) The structural system of traditional low-tower cable-stayed bridges has greatly restricted their development into wide-span and long-span bridges, and also restricted their diverse landscape development. Summary of the invention

[0008] In view of the technical problems existing in the above-mentioned traditional low-tower cable-stayed bridge system, the purpose of the present invention is to provide a wide-span and large-span hybrid beam low-tower cable-stayed bridge system and its construction method and its construction method. The low-tower cable-stayed bridge system has reasonable structural design, convenient and fast construction, good force performance and economic performance, and can meet the requirements of wide width and large span and the requirements of landscape diversity.

[0009] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0010] A wide and large span hybrid beam and low tower cable-stayed bridge system, comprising a hybrid beam arranged on both sides of the transverse bridge direction and composed of a concrete box beam 1, a corrugated web steel box-concrete composite beam 2, and a steel-concrete combined section 3;

[0011] The hybrid beams are connected by a central support concrete beam 6, a truss steel beam 7, an I-shaped steel beam 8 and an end beam 9;

[0012] The hybrid beam and each cross beam are provided with a cast-in-place bridge deck 10 and a prefabricated bridge deck 10-1;

[0013] A bridge tower 4 cast as one piece with the hybrid beam is arranged at the middle support concrete beam 6 , and a cable 5 is connected between the bridge tower 4 and the hybrid beam. The hybrid beam and the bridge tower 4 are supported on the main pier 12 and the transition pier 13 through bearings 14 .

[0014] The concrete box girder 1 is arranged on both sides of the middle support, and the arrangement length of one side is L=0.22L0~0.30L0, wherein L0 is the main span of the low-tower cable-stayed bridge. The maximum cantilever end height of the concrete box girder 1 is the lowest, and the middle support position height is the highest. The 2~4 meters on both sides of the middle support are equal height sections, and the rest are variable height sections. The beam height change curve adopts a 1.5~2.0 parabola. The concrete box girder 1 is a solid section in the equal height section and a box section in the variable height section. A number of concrete partitions 1-1 are arranged at intervals of 3~6 meters.

[0015] The corrugated web steel box-concrete composite beam 2 is arranged in the middle of the side span and the middle span, and has the same height as the maximum cantilever end of the concrete box beam 1, including a corrugated web steel box surrounded by a steel box top plate 2-1, a steel box bottom plate 2-2, and a steel box corrugated web 2-3, a first-phase cast concrete 10-3 cast on the steel box top plate 2-1, a plurality of steel box partitions 2-4 arranged at intervals of 3 to 6 meters inside the corrugated web steel box, and bottom plate stiffening ribs 2-5 arranged on the steel box bottom plate 2-2.

[0016] The steel-concrete combined section 3 is a connection structure between the concrete box beam 1 and the corrugated web steel box-concrete composite beam 2, and its height is the same as the maximum cantilever end of the concrete box beam 1, including a reserved composite beam splicing section and a steel box-concrete box combined section; the length of the reserved composite beam splicing section L1 = 0.5H ~ 2.5H, where H is the maximum cantilever end beam height of the concrete box beam 1, and the structural form is the same as the corrugated web steel box-concrete composite beam 2; the length of the steel box-concrete box combined section L2 = H ~ 2H, and its structural form is that the steel box top plate 2-1, steel box bottom plate 2-2, steel box corrugated web 2-3, and bottom plate stiffening ribs 2-5 in the reserved composite beam splicing section extend to the steel box-concrete box combined section, and are pre-welded on the embedded joint vertical plate 3-4. The embedded joint plate 3-3 is welded, and shear nails 11 are arranged on the top surface of the steel box top plate 2-1, the top surface of the steel box bottom plate 2-2, the inner side of the steel box corrugated web 2-3 and the embedded joint vertical plate 3-4. The connecting section concrete 3-1 is poured inside and on the top surface of the corrugated web steel box, and the internal cross-section is the same as the maximum cantilever end of the concrete box beam 1. A connecting section partition 3-2 that is the same as the concrete partition 1-1 is poured in the middle of the steel box-concrete box connecting section; the steel box corrugated web 2-3 is a straight steel plate without corrugation in the steel box-concrete box connecting section, and the embedded joint vertical plate 3-4 is embedded in the concrete box beam 1, with an embedded depth L3=0.3H~0.6H, and a longitudinal steel bar through-hole 3-5 is provided on the embedded joint plate 3-3.

[0017] The bridge tower 4 is in the form of a double tower column. The lower part of the bridge tower 4 is cast as a whole with the outer side of the concrete box beam 1 at the middle support point to form a tower-beam consolidation system. The bridge tower 4 and the concrete box beam 1 are supported on the main pier 12 by supports 14 arranged on both sides of the transverse bridge.

[0018] The cable-stayed cable 5 is double-cable-surfaced, one end of which is connected to the bridge tower 4, and the other end of which is connected to the concrete diaphragm 1-1 of the concrete box girder 1 on both sides of the transverse bridge direction or the steel box diaphragm 2-4 of the corrugated web steel box-concrete composite beam 2.

[0019] The middle support concrete beam 6 is a box-shaped cross section, and its two ends are cast into an integral whole with the inner side of the concrete box beams 1 on both sides of the middle support position cross bridge, and a cast-in-place bridge deck 10 is cast on the middle support concrete beam 6;

[0020] The truss steel cross beam 7 is arranged in the range where the height of the concrete box beam 1 is greater than 0.6H0, and its height is 0.4H0-0.6H0, where H0 is the beam height at the support point in the concrete box beam 1; it includes an upper chord 7-1, a lower chord 7-2, and a web member 7-3, the upper chord 7-1 is connected to the upper chord embedded rod 7-4; the lower chord 7-2 is connected to the lower chord embedded rod 7-5, and the upper chord embedded rod 7-4 and the lower chord embedded rod 7-5 are embedded in the concrete box beam 1 at a position corresponding to the concrete partition 1-1;

[0021] The I-shaped steel beam 8 is arranged within the range of the concrete box beam 1 with a height less than 0.6H0 and within the range of the corrugated web steel box-concrete composite beam 2 and the steel-concrete combined section 3, with a height of 0.5H to 0.8H, and includes a beam top plate 8-1, a beam bottom plate 8-2, a beam web 8-3, a beam stiffening plate 8-4, the beam web 8-3 is connected with a beam embedded plate 8-5 and a beam joint plate 8-6, the beam embedded plate 8-5 is embedded in the concrete box beam 1 at a position corresponding to the concrete partition 1-1, and the beam joint plate 8-6 is pre-welded on the steel box corrugated web 2-3 at a position corresponding to the steel box partition 2-4 and the combined section partition 3-2.

[0022] The end cross beam 9 has a height of 0.8H to 0.9H and is arranged at the end of the side span of the corrugated web steel box-concrete composite beam 2. It is formed by a steel box surrounded by steel plates and poured with concrete inside, and a cast-in-place bridge deck 10 is cast on its upper part.

[0023] The prefabricated bridge deck 10-1 is erected on the center support concrete beam 6, the truss steel beam 7, the I-shaped steel beam 8 and the end beam 9, and is connected to the cast-in-place bridge deck 10, the first phase poured concrete 10-3 and the top of the concrete box beam 1 through the bridge deck wet joint 10-2 to form a whole.

[0024] A construction method for a wide-span, large-span, hybrid-beam, low-tower cable-stayed bridge system, comprising:

[0025] The middle support point of the concrete box beam 1 is the middle support point segment, and the rest is divided into a plurality of standard segments; the side span beam ends of the corrugated web steel box-concrete composite beam 2 are divided into beam end closing segments, the middle span portion is the middle span closing segment, and the rest is divided into a plurality of standard segments; the steel-concrete combined segment 3 is a separate construction segment; the construction process of the constructed hybrid beam low-tower cable-stayed bridge includes the following steps:

[0026] Step 1: Construction of the lower structure: construction of the main pier 12, the transition pier 13, and installation of the support 14;

[0027] Step 2: Factory processing of steel structure and prefabricated bridge deck: while step 1 is being carried out, the corrugated web steel box-concrete composite beam 2, the steel-concrete combined section 3 steel box, the truss steel beam 7, and the I-shaped steel beam 8 are manufactured in the factory, and the prefabricated bridge deck 10-1 is cast and maintained in the factory;

[0028] Step 3, bridge tower construction: set up temporary consolidation structure and construction support of bridge tower 4 on main pier 12, cast the middle support segment of concrete box girder 1, lower part of bridge tower 4 and middle support concrete beam 6 in one piece; construct the first standard segment on both sides of the middle support of concrete box girder 1 by support cast-in-place method, install the truss steel beam 7 of the segment; then hoist the prefabricated bridge deck 10-1 of the segment, cast the cast-in-place bridge deck 10 and bridge deck wet joint 10-2 on the top of middle support concrete beam 6 to form the construction platform of bridge tower 4; finally, construct the upper part of bridge tower 4 in sections until completion;

[0029] Step 4, cantilever construction of concrete box girder 1: adopt hanging basket cantilever casting method to symmetrically cast the remaining standard sections on both sides of the support of concrete box girder 1 in sequence; after the casting of each section is completed, install the truss steel beam 7 or I-shaped steel beam 8 of the section, then tension the inclined cable 5 of the section, and finally hoist the prefabricated bridge deck 10-1 of the section and cast the bridge deck wet joint 10-2; in this order, construct each standard section of concrete box girder 1 one by one until the maximum cantilever end of concrete box girder 1; when constructing the last standard section, embed the embedded joint vertical plate 3-4 and the embedded joint flat plate 3-3;

[0030] Step 5, construction of steel-concrete combined section 3: hoist the steel box of the steel-concrete combined section 3 to the docking position with the last standard section of the concrete box beam 1, weld the steel box and the embedded joint plate 3-3 firmly, then pour the combined section concrete 3-1 and the combined section partition 3-2, finally hoist the I-shaped steel beam 8 of this section, the prefabricated bridge deck 10-1 and pour the bridge deck wet joint 10-2;

[0031] Step 6, hoisting and splicing of web steel box-concrete composite beam 2: hoist and splice each standard segment of corrugated web steel box-concrete composite beam 2 in sequence until it reaches the maximum symmetrical cantilever state. After the construction of each segment is completed, install the I-shaped steel beam 8 of the segment, tension the inclined cable 5 of the segment, hoist the prefabricated bridge deck 10-1 of the segment and cast the bridge deck wet joint 10-2; then hoist and splice the beam end closing segment, one end of the beam end closing segment is spliced ​​with the previous segment, and the other end is supported on the support 14 of the transition pier 13, and the I-shaped steel beam 8, end beam 9, prefabricated bridge deck 10-1 and bridge deck wet joint 10-2 of the segment are constructed in sequence to complete the side span closing; finally, hoist and splice the middle span closing segment, and construct the I-shaped steel beam 8, prefabricated bridge deck 10-1 and bridge deck wet joint 10-2 of the segment in sequence to complete the middle span closing;

[0032] Step 7: Conversion of the completed bridge system: dismantle the temporary consolidation structure of the bridge tower and the construction support at the middle support point, so that the bridge tower 4 and the hybrid beam are placed on the support 14 of the main pier 12, and the construction of the wide-span, large-span hybrid beam and low-tower cable-stayed bridge system is completed.

[0033] The beneficial effects of the present invention are:

[0034] 1. The present invention is conducive to the development of low-tower cable-stayed bridges into large-span bridges. The main beam adopts a hybrid beam, and the side span and the middle span adopt a corrugated web steel box-concrete composite beam with equal height, which can give full play to the advantages of light weight and good performance of steel, improve the bearing capacity of the low-tower cable-stayed bridge in the span, reduce the deadweight of the main beam, and increase the spanning capacity of the low-tower cable-stayed bridge. At the same time, the middle support and both sides adopt variable-height concrete box beams, and prestress can be arranged in the box beam, which can not only ensure the rigidity of the low-tower cable-stayed bridge, but also improve the bearing capacity of the negative bending moment area of ​​the main beam.

[0035] 2. The present invention is conducive to the development of low-tower cable-stayed bridges into wide-width bridges. The main beam adopts a double-sided main beam plus a cross beam structure. The structural system has clear force, good lateral stiffness and torsional stiffness. When the width of the bridge is increased, the deadweight of the bridge will not be increased too much, which can ensure the stiffness requirements and bearing capacity requirements of the structure without bringing unnecessary adverse effects to the structure.

[0036] 3. The steel-concrete combined section structure provided by the present invention has a simple structure, reasonable design, convenient construction, and easy to ensure construction quality. The reserved composite beam splicing section takes into account the requirements of the segmented hoisting splicing joints of the corrugated web steel box-concrete composite beam during construction. The length of the reserved composite beam splicing section L1 = 0.5H ~ 2.5H, and the first-phase pouring concrete pre-cast on the corrugated web steel box in this section can effectively ensure the stability of the steel box during the construction of the steel-concrete combined section. The steel box-concrete box combined section takes into account the requirements of the transition between the composite beam and the concrete box beam. The length of the steel box-concrete box combined section L2 = H ~ 2H, and the shear nails arranged on the steel box and the combined section concrete cast in the steel box can effectively and reasonably ensure the connection between the composite beam and the concrete box beam, and ensure the continuity of the force transmission of the hybrid beam. The embedded joint vertical plate and the embedded joint flat plate can provide positioning and anchoring measures for the construction of the steel-concrete combined section, effectively preventing the steel box from being displaced during the pouring and vibration of the combined section concrete, and are also measures to ensure the effective connection between the steel box and the concrete box. The embedded depth of the embedded joint vertical plate is L3 = 0.3H ~ 0.6H, and the arrangement of shear nails on it can prevent the embedded joint vertical plate from being pulled out, ensuring the stability of the connection part. The longitudinal reinforcement perforations set on the embedded joint flat plate allow the longitudinal reinforcement of the concrete box beam to pass through, effectively ensuring the continuity of the steel box-concrete box joint section and the longitudinal reinforcement in the concrete box beam.

[0037] 4. The present invention provides a reasonable arrangement length L=0.22L0~0.30L0 of the concrete box girder of the low-tower cable-stayed bridge, ensuring that the concrete box girder mainly bears the negative bending moment of the structure, the corrugated web steel box-concrete composite beam mainly bears the positive bending moment of the structure, and the steel-concrete combined section is located at the position where the main beam bending moment is minimum, so that the force on the hybrid beam is clear and reasonable, thereby simplifying the structure of the hybrid beam and reducing the cost of the low-tower cable-stayed bridge.

[0038] 5. The corrugated web steel box-concrete composite beams in the side span and mid-span have better bearing capacity of steel, and prestressing does not need to be arranged at the lower edge of the mid-span and the lower edge of the side span. Compared with the box section of the traditional low-tower cable-stayed bridge, the use of prestressing is reduced. At the same time, due to the lighter weight of the steel, the deadweight of the main beam is greatly reduced, and the cable can adopt smaller specifications, which greatly improves the economic performance of the low-tower cable-stayed bridge.

[0039] 6. The first phase of pouring concrete on the corrugated web steel box-concrete composite beam allows the corrugated web steel box to form a composite beam before hoisting, ensuring the structural stability and safety of the corrugated web steel box-concrete composite beam during construction, and also facilitating the hoisting and splicing of the composite beam.

[0040] 7. The bridge tower adopts double tower columns and is cast as one with the outer side of the concrete box beam. The concrete box beams on both sides of the cross bridge are connected by a central support concrete beam. Prestress can be arranged in the beam, forming a bridge tower foundation structure with good force performance, which can effectively ensure the formation of the tower-beam consolidation system. At the same time, the double tower columns also provide more room for the design of the bridge tower, solving the problem of the single-column tower form of the traditional low-tower cable-stayed bridge, and can greatly improve the landscape performance of the low-tower cable-stayed bridge.

[0041] 8. The cable-stayed cable is anchored on the double main beams on both sides of the transverse bridge to form a double cable surface, which can be applied to the diversified shapes of bridge towers. At the same time, for wide bridges, the lateral force of the main beam is clear, and the cable force is transmitted to the cross beam and bridge deck through the double main beams, which greatly reduces the shear lag effect and improves the force performance of the main beam.

[0042] 9. Concrete box beams are connected by truss-type steel beams and I-shaped steel beams instead of traditional concrete beams, which can not only ensure the rigidity requirements of the structure, but also reduce the deadweight of the structure and improve the force-bearing performance of the main beam. At the same time, the height of the truss-type steel beam is 0.4H0~0.6H0, and the height of the I-shaped steel beam is 0.5H~0.8H. The two types of beams are arranged in the range of concrete box beam height greater than 0.6H0 and less than 0.6H0, respectively, which can well adapt to the requirements of concrete box beam height changes on beam height and improve the rigidity of the main beam.

[0043] 10. The truss-type steel cross beam is connected to the concrete box beam through the upper chord embedded rod and the lower chord embedded rod, the I-shaped steel cross beam is connected to the concrete box beam through the cross beam embedded plate, and is connected to the corrugated web steel box-concrete composite beam through the cross beam joint plate. The above connection form has simple structure, reasonable design, convenient construction, easy to ensure construction quality, can effectively ensure the connection performance of the main beam and the cross beam, and improve the overall stiffness of the main beam.

[0044] 11. The bridge deck adopts a combination of prefabricated bridge deck, bridge deck wet joints and cast-in-place bridge deck, which greatly facilitates the construction. The prefabricated hoisting of the bridge deck speeds up the construction progress. At the same time, the bridge deck wet joints and cast-in-place bridge deck can also well guarantee the performance of the bridge deck. The bridge deck is erected between adjacent beams to form a one-way plate with mainly longitudinal force, and the force is more clear.

[0045] 12. The present invention provides a complete set of supporting construction methods, the construction process is convenient and fast, the construction progress can be accelerated, the construction period can be shortened, and the construction quality can be easily guaranteed. Truss steel beams, I-shaped steel beams, and corrugated web steel box-concrete composite beams are processed and manufactured in factories, the quality of steel structure construction is easy to guarantee, and the steel structure and concrete structure are constructed simultaneously, which greatly shortens the construction period and accelerates the construction progress. The support section in the concrete box beam and the first standard section on both sides are constructed by setting up brackets, and the construction of the beams and bridge decks is completed in time, which can provide a working platform for the construction of the bridge tower. The remaining sections of the concrete box beam are constructed according to the hanging basket cantilever, and the construction process is simple and fast. The corrugated web steel box hoisted first in the steel-concrete combined section can provide a construction template for the concrete pouring of the combined section. At the same time, the structure of the combined section can effectively ensure the positioning and fixation of the corrugated web steel box in the combined section, and the corrugated web steel box is not easy to deviate during the construction process. During the hoisting and splicing construction of the corrugated web steel box-concrete composite beam, it can be divided into larger segment lengths to speed up the construction progress. Moreover, after the hoisting and splicing of the corrugated web steel box-concrete composite beam, the cross beams, bridge decks and inclined cables can be constructed in a timely manner to ensure the stable advancement of the structural system during the construction process, reduce the use of construction supports, and increase work efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 This is a elevation view of a wide-span, large-span, hybrid-beam, low-tower cable-stayed bridge system according to an embodiment of the present invention;

[0047] Figure 2 This is a plan view of a wide-span, large-span, hybrid-beam, low-tower cable-stayed bridge system according to an embodiment of the present invention;

[0048] Figure 3 is a cross-sectional view of a bridge tower according to an embodiment of the present invention;

[0049] Figure 4 This is a cross-sectional view of the hybrid beam taken along line AA of an embodiment of the present invention;

[0050] Figure 5 It is a cross-sectional view of a hybrid beam BB according to an embodiment of the present invention;

[0051] Figure 6 It is a CC cross-sectional view of a hybrid beam according to an embodiment of the present invention;

[0052] Figure 7 It is a DD cross-sectional view of a hybrid beam according to an embodiment of the present invention;

[0053] Figure 8 is a cross-sectional view of the hybrid beam EE according to an embodiment of the present invention;

[0054] Fig. 9 This is an elevation view of a steel-concrete combination section according to an embodiment of the present invention;

[0055] Fig.10 This is a plan view of a steel-concrete combination section according to an embodiment of the present invention;

[0056] Fig.11 This is a cross-sectional view of the steel-concrete combination section FF of an embodiment of the present invention;

[0057] Fig.12 This is a cross-sectional view of the steel-concrete combination section GG of the embodiment of the present invention

[0058] As shown in the figure: 1—concrete box girder; 1-1—concrete diaphragm; 2—corrugated web steel box-concrete composite beam; 2-1—steel box top plate; 2-2—steel box bottom plate; 2-3—steel box corrugated web; 2-4—steel box diaphragm; 2-5—bottom plate stiffening rib; 3—steel-concrete joint section; 3-1—joint section concrete; 3-2—joint section diaphragm; 3-3—embedded joint flat plate; 3-4—embedded joint vertical plate; 3-5—longitudinal steel bar perforation; 4—bridge tower; 5—inclined cable; 6—mid-support concrete beam; 7—truss steel beam; 7-1— Upper chord; 7-2—lower chord; 7-3—web member; 7-4—embedded rod for upper chord; 7-5—embedded rod for lower chord; 8—I-shaped steel beam; 8-1—beam top plate; 8-2—beam bottom plate; 8-3—beam web plate; 8-4—beam stiffening plate; 8-5—beam embedded plate; 8-6—beam joint plate; 9—end beam; 10—cast-in-place bridge deck; 10-1—precast bridge deck; 10-2—bridge deck wet joint; 10-3—first-stage concrete pouring; 11—shear studs; 12—main pier; 13—transition pier; 14—support. DETAILED DESCRIPTION

[0059] The technical solution of the present invention is further described below with reference to the accompanying drawings and through specific embodiments:

[0060] Example 1

[0061] Combination Figures 1 to 12 In this embodiment, the span combination of the hybrid beam low-tower cable-stayed bridge is (150+250+150) m, that is, the main span L0 of the low-tower cable-stayed bridge is 250 m, and the bridge deck width is 32.5 m, which is arranged in a straight line.

[0062] The hybrid beam and low-tower cable-stayed bridge of this embodiment comprises: a hybrid beam arranged on both sides of the transverse bridge direction, which is composed of a concrete box beam 1, a corrugated web steel box-concrete composite beam 2, and a steel-concrete combined section 3; a middle support concrete beam 6, a truss steel beam 7, an I-shaped steel beam 8, and an end beam 9 connecting the hybrid beams on both sides of the transverse bridge direction; a cast-in-place bridge deck 10, a prefabricated bridge deck 10-1, and a bridge deck wet joint 10-2 arranged on the hybrid beam and each beam; a bridge tower 4 cast as one piece with the hybrid beam at the middle support; a cable 5 connected between the bridge tower 4 and the hybrid beam; and a main pier 12 and a transition pier 13 supporting the hybrid beam through a support 14. The concrete box beam 1, the corrugated web steel box-concrete composite beam 2, and the steel-concrete combined section 3 are all arranged along the longitudinal bridge direction; the middle support concrete beam 6, the truss steel beam 7, the I-shaped steel beam 8, and the end beam 9 are all arranged along the transverse bridge direction.

[0063] Concrete box girder 1 is arranged on both sides of the middle support, with a single-side arrangement length of L = 0.26L0 = 65m, the maximum cantilever end beam height H = 3m, the beam height at the middle support H0 = 10m, 3 meters on both sides of the middle support are equal height sections, and the rest are variable height sections. The beam height change curve adopts a 1.8-order parabola, the equal height section is a solid section, the variable height section is a box section, and a concrete partition 1-1 is set every 4m. The bottom width of concrete box girder 1 is 3m, the top width is 3.5m, the top plate thickness of the box section is 50cm, the bottom plate thickness changes from 70cm to 110cm according to a 1.8-order parabola, the web thickness is 60cm near the maximum cantilever end, and 80cm near the middle support, with a linear transition in the middle.

[0064] The corrugated web steel box-concrete composite beam 2 is arranged in the middle of the side span and the middle span, with a length of 77m in the side span and 104m in the middle span, and a beam height of 3m. It includes a corrugated web steel box surrounded by two steel box top plates 2-1, one steel box bottom plate 2-2, and two steel box corrugated webs 2-3, a first-stage cast concrete 10-3 cast on the steel box top plate 2-1, a steel box partition 2-4 arranged at intervals of 4m inside the corrugated web steel box, and two bottom plate stiffening ribs 2-5 arranged on the steel box bottom plate 2-2. The steel box top plate 2-1 is 40mm thick, the steel box bottom plate 2-2 is 55mm thick, the steel box corrugated web 2-3 is 28mm thick, the first-stage cast concrete 10-3 is 250mm thick, the corrugated web steel box is 2750mm high, and the corrugated web steel box-concrete composite beam 2 is 3m wide at the bottom and 3.5m wide at the top.

[0065] The steel-concrete combined section 3 is a connection structure between the concrete box beam 1 and the corrugated web steel box-concrete composite beam 2. The beam height is 3m, and includes a reserved composite beam splicing section and a steel box-concrete box combined section.

[0066] The length of the reserved composite beam splicing section L1=1.33H=4m, and its structural form and size structure are the same as those of the corrugated web steel box-concrete composite beam 2.

[0067] The length of the steel box-concrete box joint section is L2=1.33H=4m, and its structural form is that the steel box top plate 2-1, steel box bottom plate 2-2, steel box corrugated web 2-3, and bottom plate stiffening rib 2-5 in the reserved composite beam splicing section extend to the steel box-concrete box joint section, and are welded to the embedded joint flat plate 3-3 welded on the embedded joint vertical plate 3-4. Shear nails 11 are arranged at a spacing of 150mm on the top surface of the steel box top plate 2-1, the top surface of the steel box bottom plate 2-2, and the inner side of the steel box corrugated web 2-3. The joint section concrete 3-1 is poured inside and on the top surface of the corrugated web steel box, and the same cross-sectional form as the maximum cantilever end of the concrete box beam 1 is formed inside. A joint section partition 3-2 identical to the concrete partition 1-1 is poured in the middle of the steel box-concrete box joint section. The steel box corrugated web 2-3 is a straight steel plate without corrugation in the steel box-concrete box joint section. Shear nails 11 are arranged on the embedded joint vertical plate 3-4 at a spacing of 150 mm, which are pre-welded with the embedded joint flat plate 3-3 and embedded in the concrete box beam 1, with an embedded depth of L3 = 0.4H = 1.2 m. The embedded joint flat plate 3-3 is provided with longitudinal steel bar through-holes 3-5 for the longitudinal steel bars of the concrete box beam 1 to pass through. The thickness of the embedded joint flat plate 3-3 and the embedded joint vertical plate 3-4 are both 28 mm.

[0068] The bridge tower 4 is a curved bridge tower with double tower columns. The tower columns are concrete box-sections. The lower part of the bridge tower 4 is cast as a whole with the outer side of the concrete box girder 1 at the mid-support position to form a tower-beam consolidation system. The bridge tower 4 and the concrete box girder 1 are supported on the main pier 12 by supports 14 arranged on both sides of the transverse bridge. The main pier 12 is a V-shaped pier, which combines with the curve of the bridge tower 4 to form a bud-shaped appearance structure.

[0069] The cable-stayed cable 5 is a double-cable plane, one end of which is connected to the bridge tower 4, and the other end is connected to the concrete diaphragm 1-1 of the concrete box girder 1 on both sides of the transverse bridge or the steel box diaphragm 2-4 of the corrugated web steel box-concrete composite beam 2. The cable spacing on the hybrid beam is 8m, and a total of 96 cables are arranged in the whole bridge.

[0070] The middle support concrete beam 6 is a box-type section with a section height of 9750mm and a width of 6000mm. The two ends of the middle support concrete beam 6 are cast as a whole with the inner sides of the concrete box beams 1 on both sides of the middle support position cross bridge. A 250mm thick cast-in-place bridge deck 10 is cast on the middle support concrete beam 6.

[0071] The truss steel cross beam 7 is arranged within the range where the height of the concrete box beam 1 is greater than 0.6H0=6m, and its height is 0.5H0=5m. It includes 1 upper chord 7-1, 1 lower chord 7-2, and 8 web members 7-3. It is connected to the concrete box beam 1 on both sides of the cross bridge through the connection between the upper chord 7-1 and the upper chord embedded rod 7-4 and the connection between the lower chord 7-2 and the lower chord embedded rod 7-5. The upper chord embedded rod 7-4 and the lower chord embedded rod 7-5 are embedded in the concrete box beam 1 at the position corresponding to the concrete partition 1-1. The upper chord 7-1, the lower chord 7-2, the upper chord embedded rod 7-4, and the lower chord embedded rod 7-5 are all box sections welded by steel plates, and the web member 7-3 is made of H-shaped steel. The top width and bottom width of the truss steel cross beam 7 are both 500mm.

[0072] The I-shaped steel beam 8 is arranged within the range of the height of the concrete box beam 1 less than 0.6H0=6m and within the range of the corrugated web steel box-concrete composite beam 2 and the steel-concrete combined section 3, with a height of 0.7H=2.1m, including a beam top plate 8-1, a beam bottom plate 8-2, a beam web 8-3, and 44 beam stiffening plates 8-4. Through the connection of the beam web 8-3 with the beam embedded plate 8-5 and the beam joint plate 8-6, it is connected with the concrete box beam 1, the corrugated web steel box-concrete composite beam 2 and the steel-concrete combined section 3 on both sides of the cross bridge. The beam embedded plate 8-5 is embedded in the position of the concrete box beam 1 corresponding to the concrete partition 1-1. The beam joint plate 8-6 is pre-welded to the steel box corrugated web 2-3 corresponding to the steel box partition 2-4 and the combined section partition 3-2. The top width and bottom width of the I-shaped steel beam 8 are both 500mm.

[0073] The end cross beam 9 has a height of 0.9H=2.7m and is arranged at the end of the side span beam, connecting the corrugated web steel box-concrete composite beam 2 on both sides of the transverse bridge. It is formed by a steel box surrounded by steel plates and poured with concrete inside, and a 250mm thick cast-in-place bridge deck 10 is cast on its upper part.

[0074] The precast bridge deck 10-1 is erected on the middle support concrete beam 6, the truss steel beam 7, the I-shaped steel beam 8 and the end beam 9, and is connected to the cast-in-place bridge deck 10, the first-stage poured concrete 10-3 and the top of the concrete box girder 1 through the bridge deck wet joint 10-2 to form a whole. The thickness of the precast bridge deck 10-1, the bridge deck wet joint 10-2, the cast-in-place bridge deck 10 and the first-stage poured concrete 10-3 is 250 mm.

[0075] In this embodiment, the construction sections of the concrete box girder 1 on one side of the bridge tower are divided into: the range of 5m from the middle support is the middle support section, and then it is divided into 15 standard sections at 4m each. The construction sections of the corrugated web steel box-concrete composite beam 2 of the side span are divided into: the range of 29m from the beam end is the side span beam end section, and the rest is divided into 3 standard sections at 16m each. The construction sections of the corrugated web steel box-concrete composite beam 2 of the middle span are divided into: the range of 8m from the middle of the span is the middle span closure section, and the rest is divided into 6 standard sections at 16m each. The steel-concrete combined section 3 is a separate construction section.

[0076] The construction method of the hybrid beam low tower cable-stayed bridge of this embodiment includes:

[0077] The 5m range on both sides of the middle support of the concrete box girder 1 is the middle support segment, and the remaining part is divided into 15 standard segments at 4m each section; the construction segment of the corrugated web steel box-concrete composite beam 2 of the side span is divided into: the range of 29m from the beam end is the beam end closing segment, and the remaining part is divided into 3 standard segments at 16m each section. The construction segment of the corrugated web steel box-concrete composite beam 2 of the middle span is divided into: the range of 8m from the middle of the span is the middle span closing segment, and the remaining part is divided into 6 standard segments at 16m each section. The steel-concrete combined section 3 is a separate construction segment. The construction process of the hybrid beam low-tower cable-stayed bridge includes the following steps:

[0078] Step 1: Construction of the lower structure: construction of the main pier 12, the transition pier 13, and installation of the support 14;

[0079] Step 2: Factory processing of steel structure and prefabricated bridge deck: while step 1 is being carried out, the corrugated web steel box-concrete composite beam 2, the steel-concrete combined section 3 steel box, the truss steel beam 7, and the I-shaped steel beam 8 are manufactured in the factory, and the prefabricated bridge deck 10-1 is cast and maintained in the factory;

[0080] Step 3, bridge tower construction: set up temporary consolidation structure and construction support of bridge tower 4 on main pier 12, cast the middle support segment of concrete box girder 1, lower part of bridge tower 4 and middle support concrete beam 6 in one piece; construct the first standard segment on both sides of the middle support of concrete box girder 1 by support cast-in-place method, install the truss steel beam 7 of the segment; then hoist the prefabricated bridge deck 10-1 of the segment, cast the cast-in-place bridge deck 10 and bridge deck wet joint 10-2 on the top of middle support concrete beam 6 to form the construction platform of bridge tower 4; finally, construct the upper part of bridge tower 4 in sections until completion;

[0081] Step 4, cantilever construction of concrete box girder 1: adopt hanging basket cantilever casting method to symmetrically cast the remaining standard sections on both sides of the support of concrete box girder 1 in sequence; after the casting of each section is completed, install the truss steel beam 7 or I-shaped steel beam 8 of the section, then tension the inclined cable 5 of the section, and finally hoist the prefabricated bridge deck 10-1 of the section and cast the bridge deck wet joint 10-2; in this order, construct each standard section of concrete box girder 1 one by one until the maximum cantilever end of concrete box girder 1; when constructing the last standard section, embed the embedded joint vertical plate 3-4 and the embedded joint flat plate 3-3;

[0082] Step 5, construction of steel-concrete combined section 3: hoist the steel box of the steel-concrete combined section 3 to the docking position with the last standard section of the concrete box beam 1, weld the steel box and the embedded joint plate 3-3 firmly, then pour the combined section concrete 3-1 and the combined section partition 3-2, finally hoist the I-shaped steel beam 8 of this section, the prefabricated bridge deck 10-1 and pour the bridge deck wet joint 10-2;

[0083] Step 6, hoisting and splicing of web steel box-concrete composite beam 2: hoist and splice each standard segment of corrugated web steel box-concrete composite beam 2 in sequence until it reaches the maximum symmetrical cantilever state. After the construction of each segment is completed, install the I-shaped steel beam 8 of the segment, tension the inclined cable 5 of the segment, hoist the prefabricated bridge deck 10-1 of the segment and cast the bridge deck wet joint 10-2; then hoist and splice the beam end closing segment, one end of the beam end closing segment is spliced ​​with the previous segment, and the other end is supported on the support 14 of the transition pier 13, and the I-shaped steel beam 8, end beam 9, prefabricated bridge deck 10-1 and bridge deck wet joint 10-2 of the segment are constructed in sequence to complete the side span closing; finally, hoist and splice the middle span closing segment, and construct the I-shaped steel beam 8, prefabricated bridge deck 10-1 and bridge deck wet joint 10-2 of the segment in sequence to complete the middle span closing;

[0084] Step 7: Conversion of the completed bridge system: dismantle the temporary consolidation structure of the bridge tower and the construction support at the middle support point, so that the bridge tower 4 and the hybrid beam are placed on the support 14 of the main pier 12, and the construction of the wide-span, large-span hybrid beam and low-tower cable-stayed bridge system is completed.

[0085] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0086] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A wide and long span hybrid beam and low tower cable-stayed bridge system, characterized in that: It includes a hybrid beam arranged on both sides of the transverse bridge, which is composed of a concrete box beam, a corrugated web steel box-concrete composite beam, and a steel-concrete combined section; The hybrid beams are connected by a central support concrete beam, a truss steel beam, an I-shaped steel beam and an end beam; Cast-in-place bridge decks and prefabricated bridge decks are arranged on the hybrid beams and each cross beam; A bridge tower cast as one piece with the hybrid beam is arranged at the concrete cross beam at the middle support point, a stay cable is connected between the bridge tower and the hybrid beam, and the hybrid beam and the bridge tower are supported on the main pier and the transition pier through bearings; The concrete box beam is arranged on both sides of the middle support, and the arrangement length of one side is L=0.22L0~0.30L0, where L0 is the main span of the low-tower cable-stayed bridge. The maximum cantilever end of the concrete box beam has the lowest height, and the middle support position has the highest height. The two sides of the middle support are 2~4 meters each for equal height sections, and the rest are variable height sections. The beam height change curve adopts a 1.5~2.0 parabola. The concrete box beam is a solid section in the equal height section and a box section in the variable height section. A number of concrete partitions are arranged at intervals of 3~6 meters. The corrugated web steel box-concrete composite beam is arranged in the middle of the side span and the middle span, and has the same height as the maximum cantilever end of the concrete box beam, including a corrugated web steel box surrounded by a steel box top plate, a steel box bottom plate, and a steel box corrugated web, a first-stage pouring concrete poured on the steel box top plate, a plurality of steel box partitions arranged at intervals of 3 to 6 meters inside the corrugated web steel box, and bottom plate stiffening ribs arranged on the steel box bottom plate; The steel-concrete combined section is a connection structure between a concrete box beam and a steel box-concrete composite beam with a corrugated web, and its height is the same as the maximum cantilever end of the concrete box beam, and includes a reserved composite beam splicing section and a steel box-concrete box combined section; the length of the reserved composite beam splicing section L1 = 0.5H ~ 2.5H, where H is the maximum cantilever end beam height of the concrete box beam, and the structural form is the same as the corrugated web steel box-concrete composite beam; the length of the steel box-concrete box combined section L2 = H ~ 2H, and its structural form is that the steel box top plate, steel box bottom plate, steel box corrugated web, and bottom plate stiffening ribs in the reserved composite beam splicing section extend to the steel box-concrete box combined section, and are connected to the pre-welded The embedded joint flat plate connected to the embedded joint vertical plate is welded, and shear nails are arranged on the top surface of the steel box top plate, the top surface of the steel box bottom plate, the inner side of the steel box corrugated web and the embedded joint vertical plate. The connecting section concrete is poured inside and on the top surface of the corrugated web steel box, and the same cross-sectional form as the maximum cantilever end of the concrete box beam is formed inside. A connecting section partition that is the same as the concrete partition is poured in the middle of the steel box-concrete box connecting section; the steel box corrugated web is a straight steel plate without corrugation in the steel box-concrete box connecting section, and the embedded joint vertical plate is embedded in the concrete box beam, with an embedded depth of L3=0.3H~0.6H, and longitudinal steel bar perforations are arranged on the embedded joint flat plate; The middle support concrete cross beam is a box-shaped cross section, and its two ends are respectively cast as a whole with the inner sides of the concrete box beams on both sides of the cross bridge at the middle support position, and a cast-in-place bridge deck is cast on the middle support concrete cross beam; The truss-type steel cross beam is arranged in the range where the height of the concrete box beam is greater than 0.6H0, and its height is 0.4H0-0.6H0, wherein H0 is the beam height at the support point in the concrete box beam; it includes an upper chord, a lower chord, and a web member, the upper chord is connected with the upper chord embedded rod; the lower chord is connected with the lower chord embedded rod, and the upper chord embedded rod and the lower chord embedded rod are embedded in the position of the concrete box beam corresponding to the concrete partition; The I-shaped steel cross beam is arranged within the range of the concrete box beam height less than 0.6H0 and within the range of the corrugated web steel box-concrete composite beam and the steel-concrete combined section, with a height of 0.5H to 0.8H, and includes a cross beam top plate, a cross beam bottom plate, a cross beam web, a cross beam stiffening plate, the cross beam web is connected with the cross beam embedded plate and the cross beam joint plate, the cross beam embedded plate is embedded in the concrete box beam at a position corresponding to the concrete partition, and the cross beam joint plate is pre-welded on the steel box corrugated web at a position corresponding to the steel box partition and the combined section partition.

2. A wide-span, long-span hybrid beam, low-tower cable-stayed bridge system according to claim 1, characterized in that: The bridge tower is in the form of a double tower column. The lower part of the bridge tower is cast as a whole with the outer side of the concrete box beam at the middle support point to form a tower-beam consolidation system. The bridge tower and the concrete box beam are supported on the main pier by supports arranged on both sides of the transverse bridge.

3. The wide-span, long-span hybrid beam, low-tower cable-stayed bridge system according to claim 1 is characterized by: The cable-stayed cable is double-cable-surfaced, one end of which is connected to the bridge tower, and the other end of which is connected to the concrete diaphragm of the concrete box girder on both sides of the transverse bridge or the steel box diaphragm of the corrugated web steel box-concrete composite beam.

4. The wide-span, long-span hybrid beam, low-tower cable-stayed bridge system according to claim 1 is characterized by: The end cross beam has a height of 0.8H to 0.9H and is arranged at the side span end of the corrugated web steel box-concrete composite beam. It is formed by surrounding a steel box with steel plates and pouring concrete inside, and a cast-in-place bridge deck is cast on its upper part.

5. The wide-span, long-span hybrid beam, low-tower cable-stayed bridge system according to claim 1 is characterized by: The prefabricated bridge deck is erected on the center support concrete beam, truss steel beam, I-shaped steel beam and end beam, and is connected with the cast-in-place bridge deck, the first phase poured concrete and the top of the concrete box beam through the bridge deck wet joint to form a whole.

6. A construction method for a wide-width, large-span, hybrid-beam, low-tower cable-stayed bridge system as claimed in any one of claims 1 to 5, characterized in that: include: S1. Construct the main pier and transition pier, and install the bearings; S2, factory processing of steel structures and prefabricated bridge decks; S3, bridge tower construction; S4, cantilever construction of concrete box beam; S5, construction of steel-concrete combined section; S6, hoisting and splicing of web steel box-concrete composite beam; S7, complete the bridge system conversion and complete the construction of the wide-span, large-span, hybrid beam, low-tower cable-stayed bridge system.

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