An asymmetric balanced cantilever construction method for a corrugated steel web hybrid girder bridge

Abstract

The present application relates to the technical field of bridge, provide a kind of corrugated steel web hybrid girder bridge asymmetric balanced cantilever construction method, by applying one-stage weight in side span box, and real-time monitoring pier top bending moment in the process of one-side cantilever of main span side, dynamically apply or adjust two-stage weight, avoid insufficient or excessive weight. After side span closure, actively retain pier top temporary support, maintain temporary consolidation, so that side span bears the unbalanced bending moment generated by subsequent cantilever, without setting up large temporary counterweight, adapt to soft foundation. The second type of beam section is used in the middle of main span, which is steel bottom plate + ultra-high performance concrete composite top plate + corrugated steel web, the self-weight is reduced by about 50%, the crossing capacity is improved, and the risk of bottom plate cracking is eliminated. The present application allows the side-to-middle span ratio to be flexibly designed within the range of 0.35-0.60, significantly reducing the size of the bridge and the engineering cost. The present application is highly adaptable to soft foundations such as lake areas and offshore areas, and simultaneously solves the problems of mid-span deflection and web cracking.

Description

Technical Field

[0001] This invention relates to the field of bridge engineering technology, and in particular to an asymmetric balanced cantilever construction method for corrugated steel web hybrid beam bridges. Background Technology

[0002] Conventional corrugated steel web composite beam bridges have heavy self-weight, and there is a risk of cracking in the mid-span bottom slab. In the design of existing long-span beam bridges, the side-to-mid-span ratio is usually not less than 0.55 to prevent excessive negative reaction forces at the side-span supports. However, a larger side-to-mid-span ratio leads to an increase in bridge length (construction scale), which is not conducive to the control of bridge scale and project cost.

[0003] There are few existing cases of segmental cantilever construction of corrugated steel web composite beams, and all of them are based on symmetrical cantilever construction techniques. For bridges with a small side-to-mid span ratio, if symmetrical cantilever construction is still used, a large number of temporary counterweights need to be installed on the side spans to balance the cantilever load on the main span side. This not only increases the cost of measures but also has poor adaptability to soft foundations. If an asymmetrical construction sequence is adopted, with the side spans closed first and then the main span cantilevered on one side, the problem arises that the temporary supports on the pier tops are removed after the side spans are closed, making it unable to withstand the unbalanced bending moment generated by the single-side cantilever construction. Therefore, it is necessary to increase the side-to-mid span ratio or install large temporary counterweights, leading to an increase in project costs.

[0004] In addition, existing ballast methods are mostly one-time fixed ballast (such as pouring concrete inside the box), which cannot be dynamically adjusted according to the bending moment at the top of the pier monitored in real time during construction. Once the ballast is insufficient or excessive, it is difficult to remedy, resulting in high construction risks and serious material waste.

[0005] In view of this, it is necessary to propose an asymmetric balanced cantilever construction method for corrugated steel web hybrid beam bridges to solve or at least alleviate the above-mentioned defects. Summary of the Invention

[0006] The main objective of this invention is to provide an asymmetric balanced cantilever construction method for corrugated steel web composite beam bridges, in order to solve the technical problems of existing corrugated steel web composite beam bridges with a small side-to-mid span ratio (≤0.55), where conventional symmetrical cantilever construction requires a large number of temporary counterweights on the main span side to balance the cantilever load, resulting in high costs and poor adaptability to soft foundations.

[0007] To achieve the above objectives, the present invention provides an asymmetric balanced cantilever construction method for corrugated steel web hybrid beam bridges, comprising the following steps: S1, the construction pier and 0# beam segment, several Class I beam segments are symmetrically cantilevered and assembled on both sides of the 0# beam segment; each Class I beam segment includes a first concrete top slab, a first concrete bottom slab and a first corrugated steel web; S2, continue the symmetrical cantilever assembly of the first type of beam segment on the side span to the last segment before the side span closure, and at the same time complete the assembly of the connecting beam segment on the middle span. After the assembly of each first type of beam segment is completed, the internal prestressed tendons of the corresponding beam segment are tensioned. S3, construct the cast-in-place section and the precast support section of the beam end of the side span, and apply the first-stage ballast inside the box of the cast-in-place section and the precast support section; wherein, the first-stage ballast is a ballast permanently fixed to the side span; S4, complete the closure of the side span, form a stable side span structure, and retain the temporary support on the pier top; S5, the second type of beam segment is assembled by single-sided cantilever on the main span side; wherein, the second type of beam segment includes a steel bottom plate, an ultra-high performance concrete composite top plate and a second corrugated steel web; S6. During the single-sided cantilever assembly process on the main span, the unbalanced bending moment at the pier top is monitored in real time, and secondary counterweight is dynamically applied or adjusted on the top of the side span beam based on the monitoring data to keep the bending moment at the pier top within the design allowable range; wherein, the secondary counterweight is an adjustable counterweight. S7, the mid-span closure was completed, the temporary supports on the pier tops were released, the external prestressing tendons of the entire bridge were tensioned, and the system conversion was completed.

[0008] Preferably, in step S3: The prefabricated support section of the side span is a prefabricated enclosed box structure, and the top plate of the prefabricated enclosed box structure is reserved with a grouting port; The first-stage weight-bearing includes barite concrete injected into the box-shaped structure of the precast support section through the grouting port, and barite concrete poured into the box-shaped structure of the cast-in-place beam end section; wherein the unit weight of the barite concrete is ≥35kN / m³. 3 The strength grade is C30 to C40; The barite concrete, after being pressed or poured, is cured to more than 80% of its design strength and fills part of the internal space of the box body of the precast support section and the cast-in-place beam end section.

[0009] Preferably, the amount of barite concrete is obtained through the following steps: Establish a finite element model that includes bridge piers, beam segment #0, type I beam segment, combined beam segment, type II beam segment, cast-in-place beam end segment, precast support segment, side span closure segment, mid span closure segment, temporary support on pier top, and permanent support. Based on the finite element model, the entire process of single-sided cantilever splicing of the second type of beam segment on the main span after the side span is closed is simulated, and the pier top bending moment at each construction stage is calculated. The proportion of unbalanced bending moment borne by the first-phase counterweight is determined based on the side-to-middle span ratio; wherein, the proportion increases as the side-to-middle span ratio decreases; By adjusting the total amount of the first-phase load through trial calculations, the unbalanced bending moment borne by the first-phase load is made to meet the proportional requirements, and the bending moment at the top of the pier at each construction stage under the combined action of the first-phase load and the second-phase load does not exceed the maximum unbalanced bending moment allowed by the design; wherein, the second-phase load is simulated in a way that can be dynamically adjusted during the construction process. The minimum total weight of the first phase that meets the conditions is taken as the amount of barite concrete used.

[0010] Preferably, step S6 includes the following steps: S61, before pouring concrete for the cast-in-place section at the beam end of the side span, an anchoring steel plate is pre-embedded on the top of the cast-in-place section at the beam end and a positioning tenon is welded onto the anchoring steel plate. The anchoring steel plate is provided with bolt holes and embedded with anchoring steel bars. When the support prefabrication section of the side span is prefabricated, an anchoring steel plate is pre-embedded on the top of the beam of the support prefabrication section and a positioning tenon is welded onto the anchoring steel plate. The anchoring steel plate is provided with bolt holes and embedded with anchoring steel bars. S62, a precast reinforced concrete counterweight block, wherein the bottom of the reinforced concrete counterweight block is provided with a positioning groove that mates with the positioning tenon, and a vertical bolt hole that passes through the reinforced concrete counterweight block, and the reinforced concrete counterweight block is connected to the bolt hole of the anchoring steel plate by bolts passing through the vertical bolt hole. S63, during the single-sided cantilever splicing of the second type of beam segment in step S5, the unbalanced bending moment at the top of the pier is monitored in real time by strain sensors embedded on both sides of the pier top and at the root bottom of beam segment #0. S64. When the monitored bending moment at the pier top reaches 60% of the maximum unbalanced bending moment allowed by the design, the installation position of the reinforced concrete counterweight on the top of the side span beam is determined according to the weight of the reinforced concrete counterweight and the bending moment to be offset. The reinforced concrete counterweight is hoisted and installed at the installation position to reduce the bending moment at the pier top to below 30% of the maximum unbalanced bending moment allowed by the design. S65. Repeat steps S63 to S64 based on real-time monitoring data until all second-type beam segments are assembled.

[0011] Preferably, step S64, which involves determining the installation position of the reinforced concrete counterweight on the top of the side span beam based on the weight of the reinforced concrete counterweight and the bending moment to be offset, includes the following steps: S641, Calculate the required moment to be offset based on the difference between the monitored pier top bending moment and 30% of the maximum unbalanced bending moment allowed by the design. S642, Based on the weight of the reinforced concrete counterweight and the bending moment value to be offset, calculate the lever arm length of the reinforced concrete counterweight from the top of the pier using the principle of moment balance. S643, Based on the lever arm length and the geometric dimensions of the top of the side span beam, determine the longitudinal installation position of the reinforced concrete counterweight block on the top of the side span beam.

[0012] Preferably, step S4 includes the following steps: S41, after the completion of the first phase of counterweight construction, install the rigid connection components of the side span closure section, hoist the corrugated steel web of the side span closure beam section, tie the top and bottom plate reinforcement, and pour the closure section concrete; S42. After the concrete strength of the closure section reaches 90% of the design strength, the prestressed tendons in the bottom slab are tensioned to form an integral whole, thus completing the closure of the side span. S43, after the side span is closed, the temporary support on the pier top is retained to maintain the temporary fixed state between the 0# beam segment and the pier. The temporary support on the pier top is used to bear the unbalanced bending moment during the subsequent single-sided cantilever splicing of the second type of beam segment on the main span.

[0013] Preferably, step S7 includes the following steps: S71. After completing the single-sided cantilever splicing of all the second-class beam segments, the steel channel beam of the mid-span closure segment is hoisted, the steel channel beam is connected to the steel bottom plate and the second corrugated steel web of the adjacent second-class beam segment, the top plate joint concrete is poured, the top plate prestressing tendons of the mid-span closure segment are tensioned, and the mid-span closure is completed. S72, after the mid-span is closed, the temporary supports on the pier tops are removed, and the weight of the beam is transferred to the permanent supports; S73, after removing the temporary supports on the pier top, tension the external prestressed tendons of the entire bridge to complete the system conversion.

[0014] Preferably, step S1 includes the following steps: S11, a temporary support is set on the top of the pier, and a permanent support installation position is reserved. A support frame is erected on the temporary support, and the 0# beam segment is poured to form a temporary connection between the 0# beam segment and the pier. S12, the first type of beam segment is symmetrically cantilevered and assembled on both sides of the 0# beam segment. After each first type of beam segment is assembled, the corresponding internal prestressed tendons of the first type of beam segment are tensioned so that the assembled first type of beam segment forms an integral load-bearing structure, and the number of assembled segments and the tensioning progress on both sides are kept symmetrical so that the load on both sides of the pier is balanced.

[0015] Preferably, the reinforced concrete counterweight is a multi-piece stacked structure, and the reinforced concrete counterweights of adjacent layers are detachably connected.

[0016] Preferably, the strain sensor includes a vibrating wire strain gauge embedded on both sides of the pier top and the root bottom surface of the 0# beam segment, and the sampling frequency of the strain sensor is not less than 1Hz.

[0017] Compared with the prior art, the present invention has the following beneficial effects: This invention applies initial counterweight within the side span box girder and dynamically applies or adjusts secondary counterweight by real-time monitoring of the pier top bending moment during single-sided cantilever assembly of the main span. This avoids construction risks and material waste caused by insufficient or excessive counterweight. It solves the problem of existing technologies having a single counterweight method and lacking dynamic adjustment capabilities.

[0018] This invention maintains the temporary connection between the 0# beam segment and the pier by actively retaining the temporary support at the top of the pier after the side span is closed, enabling the side span structure to withstand unbalanced bending moments during the subsequent single-sided cantilever construction of the main span. Compared with the traditional practice of immediately removing the temporary support after closure, this invention eliminates the need for large temporary counterweights (such as water tanks, sandbags, or concrete blocks) on the main span side, avoiding the problems of poor adaptability of temporary counterweights to soft foundations and high costs associated with such measures.

[0019] This invention employs a second type of beam segment in the main span, consisting of a steel base plate, a composite top slab of ultra-high performance concrete, and a second corrugated steel web. This reduces the self-weight by approximately 50% compared to conventional concrete bridge decks. Combined with the first and second phase counterweight systems, this significantly enhances the spanning capacity of the main span while eliminating the risk of long-term operational cracking of the mid-span base plate. It also solves the technical problems of heavy self-weight and limited spanning capacity of conventional corrugated steel web composite beams.

[0020] This invention allows for flexible design of the side-to-mid span ratio within the range of 0.35 to 0.60, which is significantly reduced compared to the lower limit of 0.55 to 0.65 for conventional bridges. This solves the technical problem of large bridge size and high engineering cost caused by excessive side-to-mid span ratio in existing technologies.

[0021] In addition, the present invention adopts cantilever assembly construction, which significantly reduces the lifting weight of the mid-span segment compared with conventional corrugated steel web composite beam segments, making it highly adaptable to soft foundations such as lake areas and near-shore areas, while solving the problems of mid-span deflection and web cracking. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of a construction method in one embodiment of the present invention; Figure 2 This is a flowchart illustrating step S6 in one embodiment of the present invention. Figure 3 This is a schematic diagram of the structure after construction step S1 in one embodiment of the present invention; Figure 4This is a schematic diagram of the structure after construction step S2 in one embodiment of the present invention; Figure 5 This is a schematic diagram of the structure after construction step S3 in one embodiment of the present invention; Figure 6 This is a schematic diagram of the structure after construction step S4 in one embodiment of the present invention; Figure 7 This is a schematic diagram of the structure after construction step S5 in one embodiment of the present invention; Figure 8 This is a schematic diagram of the structure after construction step S7 in one embodiment of the present invention; Figure 9 This is a schematic cross-sectional view of a first type of beam segment in one embodiment of the present invention; Figure 10 This is a schematic cross-sectional view of a second type of beam segment in one embodiment of the present invention; Figure 11 This is a schematic diagram of the combined beam segment in one embodiment of the present invention; Figure 12 for Figure 11 A schematic diagram of the cross-section of the joint boundary line; Figure 13 This is a schematic diagram of the prestressed tendon connection of the combined beam segment in one embodiment of the present invention; Figure 14 This is a schematic diagram of the connection of the third corrugated steel web of the combined beam segment in one embodiment of the present invention.

[0024] The objectives, features, and advantages of this invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings.

[0025] Explanation of icon numbers: 10. First type of beam segment; 110. First concrete top slab; 120. First concrete bottom slab; 130. First corrugated steel web; 140. Shear connector; 150. First joint structure; 151. First reserved duct; 20. Second type of beam segment; 210. Steel bottom plate; 220. Ultra-high performance concrete composite top slab; 221. Longitudinal rib; 222. Rib bottom steel plate; 223. First shear stud; 224. Transverse rib; 230. Second corrugated steel web; 240. Second reserved duct; 250. Longitudinal stiffening rib of bottom plate; 30. Connecting beam segment; 311. Connecting steel plate; 312. Second shear stud; 313. Integrated top slab; 314. Second concrete bottom slab; 315. Outer bottom slab; 316. First perforated steel plate; 317. Steel end plate; 318. Bottom slab prestressed tendon; 319. Through reinforcement; 320. Second perforated steel plate; 321. Angle steel connector; 322. Third corrugated steel web; 323. Twin-PBL connector; 324. Third reserved duct; 325. Internal prestressed tendon; 51. 0# beam segment; 52. Beam end cast-in-place segment; 53. Precast support segment; 54. Side span closure segment; 55. Mid-span closure segment. Detailed Implementation

[0026] It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0027] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0028] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0029] Furthermore, the descriptions of "right side," "middle side," etc., in this invention are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, features defined as "right side" or "middle side" may explicitly or implicitly include at least one of those features. Additionally, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. When the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed by this invention.

[0030] Please see the appendix Figures 1 to 14 An embodiment of the present invention provides an asymmetric balanced cantilever construction method for a corrugated steel web hybrid beam bridge, comprising the following steps: S1, construction piers and 0# beam segment 51, several first-class beam segments 10 are symmetrically cantilevered and assembled on both sides of 0# beam segment 51; wherein, each first-class beam segment 10 includes a first concrete top plate 110, a first concrete bottom plate 120 and a first corrugated steel web 130. S2, continue the symmetrical cantilever assembly of the first type of beam segment 10 on the side span to the last segment before the side span closure, and at the same time complete the assembly of the connecting beam segment 30 on the middle span side. After the assembly of each first type of beam segment 10 is completed, the internal prestressed tendons 325 of the corresponding beam segment are tensioned. S3, construct the cast-in-place section 52 and the precast support section 53 of the beam end of the side span, and apply the first-stage ballast inside the box of the cast-in-place section 52 and the precast support section 53; wherein, the first-stage ballast is a ballast permanently fixed to the side span; S4, complete the closure of the side span, form a stable side span structure, and retain the temporary support on the pier top; S5, the second type of beam segment 20 is assembled on one side of the main span by cantilever; wherein, the second type of beam segment 20 includes a steel bottom plate 210, an ultra-high performance concrete composite top plate 220 and a second corrugated steel web 230. S6. During the single-sided cantilever assembly process on the main span, the unbalanced bending moment at the pier top is monitored in real time, and secondary counterweight is dynamically applied or adjusted on the top of the side span beam based on the monitoring data to keep the bending moment at the pier top within the design allowable range; wherein, the secondary counterweight is an adjustable counterweight. S7, the mid-span closure was completed, the temporary supports on the pier tops were released, the external prestressing tendons of the entire bridge were tensioned, and the system conversion was completed.

[0031] This invention applies initial counterweight within the side span box girder and dynamically applies or adjusts secondary counterweight by real-time monitoring of the pier top bending moment during single-sided cantilever assembly of the main span. This avoids construction risks and material waste caused by insufficient or excessive counterweight. It solves the problem of existing technologies having a single counterweight method and lacking dynamic adjustment capabilities.

[0032] This invention maintains the temporary connection between beam segment 51 (0#) and the pier by actively retaining the temporary support at the top of the pier after the side span is closed, enabling the side span structure to withstand unbalanced bending moments during subsequent single-sided cantilever construction of the main span. Compared with the traditional practice of immediately removing the temporary support after closure, this invention eliminates the need for large temporary counterweights (such as water tanks, sandbags, or concrete blocks) on the main span side, avoiding the problems of poor adaptability of temporary counterweights to soft foundations and high costs associated with such measures.

[0033] This invention employs a second type of beam segment 20 in the mid-span of the main span, consisting of a steel base plate 210, an ultra-high performance concrete composite top plate 220, and a second corrugated steel web 230. This reduces the self-weight by approximately 50% compared to conventional concrete bridge decks. Combined with the first and second phase counterweight systems, this significantly enhances the spanning capacity of the main span while eliminating the risk of long-term operational cracking of the mid-span base plate. It also solves the technical problems of heavy self-weight and limited spanning capacity inherent in conventional corrugated steel web composite beams.

[0034] This invention allows for flexible design of the side-to-mid span ratio within the range of 0.35 to 0.60, which is significantly reduced compared to the lower limit of 0.55 to 0.65 for conventional bridges. This solves the technical problem of large bridge size and high engineering cost caused by excessive side-to-mid span ratio in existing technologies.

[0035] In addition, the present invention adopts cantilever assembly construction, which significantly reduces the lifting weight of the mid-span segment compared with conventional corrugated steel web composite beam segments, making it highly adaptable to soft foundations such as lake areas and near-shore areas, while solving the problems of mid-span deflection and web cracking.

[0036] In a preferred embodiment, in step S3: The precast support section 53 of the side span is a precast closed box-shaped structure, and the top slab of the precast closed box-shaped structure has reserved grouting ports. The precast support section 53 adopts a factory-precast closed box-shaped structure, and during the precasting process, multiple grouting ports are reserved at the designed positions on its top slab. The inner diameter of the grouting ports is usually 15-20cm, and the spacing is 2-3m. The cast-in-place section 52 at the beam end is constructed using the support cast-in-place method. Before pouring the top slab concrete of the cast-in-place section 52 at the beam end, its box body is in an open state. At this time, barite concrete is directly pumped or poured into the box body.

[0037] The first-stage ballast includes barite concrete injected into the box-shaped structure of the precast support section 53 through the grouting port, and barite concrete poured into the box-shaped structure of the cast-in-place beam end section 52; wherein the unit weight of the barite concrete is ≥35kN / m³. 3 The strength grade is C30 to C40; the first phase of the counterweight uses barite concrete, which has the advantages of high density and structural synergy.

[0038] The barite concrete, after being pressed or poured, is cured to more than 80% of its design strength and fills part of the internal space of the box body of the precast support section 53 and the cast-in-place beam end section 52.

[0039] In a preferred embodiment, the amount of barite concrete is obtained through the following steps: Establish a finite element model including the bridge pier, 0# beam segment 51, first type beam segment 10, combined beam segment 30, second type beam segment 20, cast-in-place beam end segment 52, precast support segment 53, side span closure segment 54, mid span closure segment 55, temporary support and permanent support on the pier top; Specifically, a three-dimensional model of the entire bridge is established using general-purpose finite element software (such as MIDAS), including piers, 0# beam segment 51, first-class beam segment 10, combined beam segment 30, second-class beam segment 20, cast-in-place beam end segment 52, precast support segment 53, side span closure segment 54, mid-span closure segment 55, temporary support on pier top (not shown in the figure), and permanent support (not shown in the figure). The cross-sectional properties, material density, and prestressed load of each component in the model can be input based on known design parameters. By establishing the finite element model, the stress changes during the entire process from side span closure to single-sided cantilever splicing of the main span can be accurately simulated.

[0040] Based on the finite element model, the entire process of single-sided cantilever splicing of the second type of beam segment 20 on the main span after the side span is closed is simulated, and the pier top bending moment at each construction stage is calculated. The construction stages are defined in the finite element model as follows: Stage 1: Apply the first-stage counterweight (according to the initial design value) and complete the side span closure; Stage 2 to Stage M: Activate the first to Mth second type of beam segments 20 on the main span in sequence. After each second type of beam segment 20 is activated, the corresponding internal prestressed tendon 325 is immediately tensioned, and the pier top bending moment value at the end of the stage is recorded.

[0041] The proportion of unbalanced bending moment borne by the first-stage counterweight is determined based on the side-to-mid-span ratio. This proportion increases as the side-to-mid-span ratio decreases. Based on the side-to-mid-span ratio λ, the proportion η of the unbalanced bending moment that the first-stage counterweight needs to bear is determined by referring to tables or based on design experience. The smaller the side-to-mid-span ratio, the weaker the balancing capacity provided by the side spans themselves, thus requiring the first-stage counterweight to bear a larger proportion. For example, when λ≤0.45, it is taken as 70%–80%; when 0.45<λ<0.55, it is taken as 60%–70%; and when λ≥0.55, it is taken as 50%–60%.

[0042] The total amount of the first-stage load was adjusted through trial calculations to ensure that the unbalanced bending moment borne by the first-stage load met the proportional requirements, and that the bending moment at the pier top during each construction stage under the combined action of the first-stage and second-stage loads did not exceed the maximum allowable unbalanced bending moment. The second-stage load was simulated in a way that allowed for dynamic adjustment during construction. The weight of the barite concrete was simulated in the finite element model by applying the first-stage load (to the cast-in-place section 52 at the beam end and the precast section 53 of the support) as a nodal load. The total amount of the first-stage load could be initially set based on experience, starting with a small initial value, and the bending moment at the pier top during each construction stage could be calculated. If the actual bending moment contributed by the first-stage load did not reach the target value required by the proportional requirements, or if the bending moment at the pier top under the combined action of the first-stage and second-stage loads exceeded the maximum allowable unbalanced bending moment, the total amount of the first-stage load was gradually increased, and the calculation was repeated until the minimum total amount of the first-stage load that met all conditions was found.

[0043] The minimum total weight of the first phase that meets the conditions is taken as the amount of barite concrete used.

[0044] Based on the minimum total initial weight and the density of barite concrete, the required volume of barite concrete can be calculated. During on-site construction, the amount of barite concrete injected is controlled according to this volume and pumped through the grouting port until the designed filling height is reached.

[0045] This implementation method can be widely applied to various corrugated steel web hybrid beam bridges with a side-to-mid span ratio of 0.35 to 0.60, providing a reliable design basis for asymmetric balanced cantilever bridges under extremely low side-to-mid span ratio conditions.

[0046] In a preferred embodiment, step S6 includes the following steps: S61, before pouring concrete for the cast-in-place section 52 at the beam end of the side span, an anchoring steel plate is pre-embedded on the top of the beam of the cast-in-place section 52 at the beam end, and a positioning tenon is welded onto the anchoring steel plate. The anchoring steel plate is provided with bolt holes and embedded with anchoring steel bars. When the prefabricated support section 53 of the side span is prefabricated, an anchoring steel plate is pre-embedded on the top of the beam of the prefabricated support section 53, and a positioning tenon is welded onto the anchoring steel plate. The anchoring steel plate is provided with bolt holes and embedded with anchoring steel bars. Before pouring concrete for the cast-in-place section 52 at the beam end of the side span, anchor steel plates are pre-embedded at the designed positions on the top of the beam. Multiple anchor steel bars are welded to the bottom surface of the anchor steel plates, bolt holes (internal threaded holes) are made on the surface of the anchor steel plates, and a positioning tenon is welded to the center of the steel plates. During the prefabrication of the support precast section 53 of the side span, anchor steel plates, positioning tenons, and anchor steel bars of the same structure are pre-embedded on the top of the beam, providing a reliable connection foundation for the subsequent installation of detachable counterweights.

[0047] S62, a precast reinforced concrete counterweight block, wherein the bottom of the reinforced concrete counterweight block is provided with a positioning groove that mates with the positioning tenon, and a vertical bolt hole penetrating the reinforced concrete counterweight block. The reinforced concrete counterweight block is connected to the bolt hole of the anchoring steel plate by bolts passing through the vertical bolt hole. The bottom of the reinforced concrete counterweight block is provided with a positioning groove that mates with the positioning tenon, and a vertical bolt hole is reserved for penetrating the reinforced concrete counterweight block. A lifting ring is pre-embedded at the top of the reinforced concrete counterweight block for easy hoisting and dismantling. By using precast standardized counterweight blocks, the factory production of counterweight blocks is realized. The detachable bolt connection allows for the dynamic addition or reduction of counterweight blocks during construction based on monitoring data, and can also be partially removed after the bridge is completed based on the alignment monitoring results, realizing the reversibility of the counterweight system.

[0048] S63, during the single-sided cantilever splicing of the second type of beam segment 20 in step S5, the unbalanced bending moment at the top of the pier is monitored in real time by strain sensors embedded on both sides of the pier top and at the root bottom of beam segment 51. During the single-sided cantilever construction of the second-class beam segment 20, vibrating wire strain gauges or fiber optic grating sensors embedded on both sides of the pier top (along the longitudinal direction of the bridge) and at the bottom of the root of beam segment 51 are used to collect the strain values ​​at the upper and lower edges of each monitoring section in real time at a sampling frequency of not less than 1Hz. The strain difference Δε between the upper and lower edges is calculated, that is, the strain difference between the upper and lower edges of the pier body section and the root section of beam segment 51 is calculated separately. Then, the bending moment at the top of the pier at each section is calculated according to the material mechanics formula M=(Δε·E·I) / h, where E is the elastic modulus of concrete, I is the moment of inertia of the section, and h is the vertical distance between the upper and lower edge measuring points. The average value of the calculated bending moments of the pier body section and the root section of beam segment 51 is taken as the final value of the unbalanced bending moment at the top of the pier. This monitoring and calculation method is a mature technology in the field of bridge construction monitoring, and those skilled in the art can implement it based on common knowledge.

[0049] S64. When the monitored bending moment at the pier top reaches 60% of the maximum unbalanced bending moment allowed by the design, the installation position of the reinforced concrete counterweight on the top of the side span beam is determined according to the weight of the reinforced concrete counterweight and the bending moment to be offset. The reinforced concrete counterweight is hoisted and installed at the installation position to reduce the bending moment at the pier top to below 30% of the maximum unbalanced bending moment allowed by the design. When the monitored bending moment at the pier top reaches 60% of the maximum allowable unbalanced bending moment, the bending moment value to be offset is calculated. This bending moment value is equal to the current monitored bending moment minus 30% of the maximum allowable unbalanced bending moment. Based on the weight of a single reinforced concrete counterweight block and the bending moment value to be offset, the lever arm length of the counterweight block from the pier top is calculated using the principle of moment balance.

[0050] In a preferred embodiment, step S64, which involves determining the installation position of the reinforced concrete counterweight on the top of the side span beam based on the weight of the reinforced concrete counterweight and the bending moment to be offset, includes the following steps: S641, Calculate the required moment to be offset based on the difference between the monitored pier top bending moment and 30% of the maximum unbalanced bending moment allowed by the design. S642, based on the weight of the reinforced concrete counterweight and the required bending moment to be offset, the lever arm length of the reinforced concrete counterweight from the pier top is calculated using the principle of moment balance. Given the weight of a single reinforced concrete counterweight, according to the principle of moment balance, the bending moment resisted by the counterweight is equal to the weight of the counterweight multiplied by the horizontal distance (lever arm) from the center of the counterweight to the centerline of the pier top. The calculated lever arm length provides a theoretical basis for determining the subsequent installation position of the reinforced concrete counterweight.

[0051] S643, Based on the lever arm length and the geometric dimensions of the top of the side span beam, determine the longitudinal installation position of the reinforced concrete counterweight block on the top of the side span beam.

[0052] Specifically, first, a list of distances (e.g., 50m, 52m, 54m, 56m, 58m) from the centerline of the pier top of all anchor steel plates at the top of the side span beam is obtained. The calculated lever arm length is compared with this list of distances: if the lever arm length equals a preset distance, that position is directly selected; if the lever arm length is between two preset distances, the preset position closest to the lever arm length is selected (if the difference between the two distances and the lever arm length is equal, the farther one is preferred to reduce the number of counterweight blocks); if the lever arm length is less than the minimum preset distance, the position with the minimum distance is selected; if the lever arm length is greater than the maximum preset distance, starting from the position with the maximum distance, a strategy of distributing or stacking multiple counterweight blocks is adopted. Through this matching, it is ensured that the counterweight blocks can be installed at the positions where anchor steel plates are pre-installed, and the deviation between the actual lever arm and the theoretical lever arm is minimized.

[0053] S65. Based on real-time monitoring data, repeat steps S63-S64 until all Class II beam segments 20 are cantilevered. After installing the reinforced concrete counterweights, continue monitoring the pier top bending moment. If, with the continued cantilevering of subsequent Class II beam segments 20, the pier top bending moment again reaches 60% of the maximum allowable unbalanced bending moment, repeat steps S63-S64, adding more counterweights at the remaining anchoring steel plate positions (or stacking them on top of existing counterweights) until all Class II beam segments 20 are cantilevered.

[0054] Further, step S4 includes the following steps: S41, after the completion of the first phase of counterweight construction, install the rigid connection components of the side span closure segment 54, hoist the corrugated steel web of the side span closure beam segment, tie the top and bottom plate reinforcement, and pour the closure segment concrete; After the first phase of ballast construction is completed (e.g., the barite concrete in the cast-in-place section 52 at the beam end and the precast support section 53 has been cured to over 80% of its design strength), the side span closure operation is carried out. First, rigid connection components (usually steel-framed stiffeners) are installed at the ends of the beam segments on both sides of the closure joint to temporarily lock the beam segments and prevent relative displacement due to temperature changes or wind loads during the closure process. Then, the corrugated steel web of the side span closure beam segment (of the same type as the corrugated steel web of the first-class beam segment 10) is hoisted and welded or bolted to the webs on both sides after placement. Next, the top and bottom slab reinforcement of the closure segment is tied and connected to the reserved reinforcement of the beam segments on both sides. Finally, the closure segment concrete is poured in a single, continuous pour.

[0055] S42. After the concrete strength of the closure section reaches 90% of the design strength, the prestressed tendons 325 in the bottom slab that tension the side span beam into a whole are tensioned to complete the side span closure. After the concrete strength of the closure section reaches 90% of the design strength, the prestressed tendons 325 in the bottom slab are tensioned to form a whole side span beam. This prestressed tendon is a continuous tendon, extending from the far end of the side span (abutment or pier) all the way to beam segment 51 #0. The side span closure is completed by simultaneous tensioning at both ends.

[0056] S43. After the side span is closed, the temporary support at the pier top is retained to maintain the temporary fixed connection between beam segment 51 (0#) and the pier. This temporary support is used to withstand unbalanced bending moments during the subsequent single-sided cantilever assembly of the second type of beam segment 20 on the main span. After the side span is closed, the temporary support at the pier top is not removed but remains in working condition to maintain the temporary fixed connection between beam segment 51 (0#) and the pier. At this time, the permanent support still maintains a 2-5cm gap with the bottom of the beam and does not participate in load-bearing. The retained temporary support will provide the bending restraint required to resist unbalanced bending moments during the subsequent single-sided cantilever assembly of the second type of beam segment 20 on the main span.

[0057] Further, step S7 includes the following steps: S71. After completing the single-sided cantilever splicing of all second-class beam segments 20, the steel channel beam of the mid-span closure segment 55 is hoisted, and the steel channel beam is connected to the steel bottom plate 210 and the second corrugated steel web 230 of the adjacent second-class beam segment 20. The top plate joint concrete is poured, and the top plate prestressing tendons of the mid-span closure segment 55 are tensioned to complete the mid-span closure. After completing the single-sided cantilever assembly of all Class II beam segments 20, the mid-span closure operation is carried out. Choosing the early morning hours when temperatures are most stable, the steel channel beam of the mid-span closure segment 55 is hoisted and transported above the closure joint, then slowly lowered into place. Next, the steel channel beam is connected to the adjacent Class II beam segment 20's steel base plate 210 and second corrugated steel web 230: butt welds are used between the steel base plates 210, and high-strength bolts or butt welds are used between the corrugated steel webs to ensure continuous force flow. After connection, the top slab joint concrete is poured. Finally, the prestressed tendons of the top slab of the mid-span closure segment 55 are tensioned and anchored to complete the mid-span closure.

[0058] S72, after the mid-span is closed, the temporary supports on the pier tops are removed, and the weight of the beam is transferred to the permanent supports. After the mid-span is closed and the top slab is tensioned, the system conversion is carried out. First, the temporary supports on the pier tops are removed. As the temporary supports are unloaded, the beam gradually falls, and the vertical load and bending moment originally borne by the temporary supports are gradually transferred to the permanent supports.

[0059] S73. After removing the temporary supports at the pier tops, tension the external prestressing tendons for the entire bridge, completing the system conversion. After removing the temporary supports at the pier tops and transferring the load to the permanent supports, tension the external prestressing tendons for the entire bridge. According to design requirements, the external tendons are tensioned in batches and symmetrically to complete the system conversion. This part is a mature construction process and will not be elaborated here.

[0060] Further, step S1 includes the following steps: S11, a temporary support is set on the top of the pier, and a permanent support installation position is reserved. A support frame is erected on the temporary support, and the 0# beam segment 51 is poured to form a temporary connection between the 0# beam segment 51 and the pier. After the pier construction is completed, temporary supports are installed on the pier top, while a permanent support installation location is reserved at the designed position. A scaffold is erected on the temporary supports, and then concrete for beam segment 0 is poured. Once the concrete reaches its design strength, beam segment 051 is temporarily fixed to the pier through the temporary supports.

[0061] S12, the first type of beam segments 10 are symmetrically cantilevered and assembled on both sides of the 0# beam segment 51. After each first type of beam segment 10 is assembled, the corresponding internal prestressing tendons 325 are tensioned, so that the assembled first type of beam segments 10 form an integral load-bearing structure, and the number of assembled segments and the tensioning progress on both sides are kept symmetrical to balance the load on both sides of the pier. A bridge deck crane is installed on the top surface of the 0# beam segment 51. First, the first type of beam segments 10 are symmetrically hoisted on both sides of the 0# beam segment 51. The internal prestressing tendons 325 passing through the first type of beam segment 10 and the assembled beam segments are tensioned. The tendons are passed through and tensioned once after each beam segment is assembled, so that the newly assembled beam segment and the existing structure form an integral load-bearing structure.

[0062] Preferably, the reinforced concrete ballast block is a multi-layered stacked structure, with adjacent layers of reinforced concrete ballast blocks being detachably connected. By designing the reinforced concrete ballast block as a multi-layered stacked structure with detachable connections between adjacent layers, construction personnel can adjust the total ballast weight by increasing or decreasing the number of ballast block layers as needed based on the real-time monitored unbalanced bending moment at the pier top.

[0063] As a preferred example, the strain sensor includes vibrating wire strain gauges embedded on both sides of the pier top and the root bottom surface of beam segment 51 #0, and the sampling frequency of the strain sensor is not less than 1Hz.

[0064] To facilitate a further understanding of the technical solution of this application, the inventors also provide a structural feature scheme for a corrugated steel web hybrid beam bridge obtained through this construction method, as follows: A corrugated steel web hybrid beam bridge includes at least one mid-span and side spans respectively disposed on both sides of the mid-span; wherein: the side spans and the mid-span are both composed of multiple first-type beam segments 10 in the region near the piers, each first-type beam segment 10 including a first concrete top slab 110, a first concrete bottom slab 120 and a first corrugated steel web 130; the use of first-type beam segments 10 in the region near the piers utilizes the compressive strength and self-weight characteristics of the concrete bottom slab to both meet the stress requirements of the negative bending moment zone and provide counterweight for the side spans. Adjacent first-type beam segments 10 can be assembled using a first joint structure 150 as described in the following embodiment.

[0065] The mid-span region of the mid-span is composed of at least one second type beam segment 20. Each second type beam segment 20 includes a steel bottom plate 210, an ultra-high performance concrete composite top plate 220, and a second corrugated steel web 230. Adjacent second type beam segments 20 can be assembled by a second joint structure (not shown) in the following embodiment.

[0066] The mid-span also includes two symmetrically arranged connecting beam segments 30, which connect adjacent first type beam segments 10 and second type beam segments 20. The connecting beam segments 30 are used to realize the transition connection between the first type beam segments 10 and the second type beam segments 20. The first type beam segments 10, the second type beam segments 20 and the connecting beam segments 30 are all precast beam segments in the factory.

[0067] This invention achieves a significant improvement in span capacity through a longitudinally partitioned structural design. Specifically, the areas of the side spans and middle spans near the piers are designated as Class I beam segments 10 (first concrete top slab 110 + first concrete bottom slab 120 + first corrugated steel web 130), while the mid-span area is designated as Class II beam segments 20 (steel bottom slab 210 + ultra-high performance concrete composite top slab 220 + second corrugated steel web 230). A smooth transition between the two structural forms is achieved by combining beam segments 30. This structural design fully utilizes the advantages of concrete's good compressive strength and low cost in the negative bending moment zone, and the advantages of steel's good tensile strength and ultra-high performance concrete's lightweight and high strength in the positive bending moment zone. Compared to conventional corrugated steel web composite beam bridges, the structural self-weight is significantly reduced. The use of concrete bottom slabs in the side spans effectively provides structural counterweight under asymmetrical conditions, making it possible to further reduce the side-to-middle span ratio. The applicable range of the side-to-middle span ratio is wider (0.35~0.60), and it can be applied to situations such as widening existing cable-stayed bridges, arch bridges, and suspension bridges.

[0068] This invention employs a ribbed ultra-high performance concrete composite top slab 220 in the mid-span area. The top slab structure is changed from a regular concrete slab to an ultra-high performance concrete ribbed composite structure, ensuring the required arrangement of 325 prestressed tendons within the beam segment near the pier top. The number of 325 prestressed tendons within the beam segment near the mid-span is reduced, and the top slab is changed to an ultra-high performance concrete ribbed composite structure. The cantilever construction does not require the installation of external temporary cable structures, reducing the average slab thickness to only 13-15cm and the self-weight to about 50%.

[0069] This invention uses a steel base plate 210 to replace the concrete base plate in the mid-span area. By utilizing the excellent tensile properties of steel, the base plate will not crack under positive bending moment, thus completely eliminating the risk of long-term operation cracking of the mid-span base plate and significantly improving the durability and service life of the structure.

[0070] The precast composite beam segment 30 structure provided by this invention is suitable for rapid precast assembly and construction, and also provides a reliable force transfer structure for two different beam types. All bridge segments use corrugated steel web connections, facilitating standardization of the process.

[0071] In a preferred embodiment, in the first type of beam segment 10: shear connectors 140 are provided at both the upper and lower ends of the first corrugated steel web 130, and the shear connectors 140 are embedded in the first concrete top slab 110 and the first concrete bottom slab 120; the first concrete top slab 110 is connected to the upper end of the first corrugated steel web 130 through the shear connectors 140, and the first concrete bottom slab 120 is connected to the lower end of the first corrugated steel web 130 through the shear connectors 140. Preferably, the shear connector 140 can be a stud connector or a PBL shear key, and is evenly arranged at intervals of 150-200mm along the longitudinal direction of the first corrugated steel web 130. The shear connector 140 is embedded in the first concrete top slab 110 and the first concrete bottom slab 120. Specifically, during the factory prefabrication stage, the shear connector 140 is welded to the upper and lower edges of the corrugated steel web, and then the top and bottom slab reinforcement is tied and C50-C60 concrete is poured in one go, so that the concrete and the steel web form a reliable combination through the shear connector 140. In this way, when the beam segment is subjected to bending moment and shear force, the shear connector 140 transfers the longitudinal shear force in the concrete top and bottom slabs to the first corrugated steel web 130, so that the three work together to bear the force.

[0072] The end of the first type of beam segment 10 is provided with a first joint structure 150. The first joint structure 150 includes a first reserved channel 151 through which the prestressed tendon 325 passes and a first shear key (not shown in the figure). In two adjacent first type of beam segments 10, the first protruding shear key provided on the end face of one first type of beam segment 10 and the first recessed shear groove provided on the end face of the other first type of beam segment 10 cooperate with each other. The gap between the first protruding shear key and the first recessed shear groove is filled with joint adhesive.

[0073] Specifically, in two adjacent Class I beam segments 10, a first protruding shear key on one end face and a first recessed shear groove on the other end face cooperate with each other. During assembly, a 2-3 mm thick epoxy resin joint adhesive is first applied to the end face, and a compressive stress of 0.5-1.0 MPa is applied by a temporary tie rod to make the first protruding shear key embed into the first recessed shear groove, forming a dual shear resistance mechanism of adhesive bonding and mechanical interlocking.

[0074] In a preferred embodiment, in the second type of beam segment 20: The ultra-high performance concrete composite roof slab 220 is a ribbed composite structure, including multiple longitudinal ribs 221 evenly arranged along the transverse direction of the bridge; the bottom of the longitudinal ribs 221 is provided with a rib bottom steel plate 222, and a first shear nail 223 is fixed on the rib bottom steel plate 222. As a preferred example, the ultra-high performance concrete composite roof slab 220 is a ribbed composite structure, including multiple longitudinal ribs 221 evenly arranged along the transverse direction of the bridge. A rib bottom steel plate 222 is provided at the bottom of the longitudinal rib 221, and a first shear stud 223 is welded on the rib bottom steel plate 222. The shear studs are arranged at intervals of 150-200mm, and the ultra-high performance concrete of the longitudinal rib 221 forms a combined force through the first shear studs 223. By adopting this ribbed composite structure, the average thickness of the top slab is reduced from that of conventional concrete top slabs to 13-15 cm, and the self-weight is reduced by about 50%. Ultra-high performance concrete has high compressive strength but relatively limited tensile strength. The bottom steel plate 222 provides additional tensile strength, enabling the ultra-high performance concrete composite top slab 220 to withstand the tensile stress generated by positive bending moment. At the same time, it serves as the fixing base for the first shear stud 223, realizing the combined effect of the steel plate and ultra-high performance concrete. The first shear stud 223 transfers the tensile force borne by the bottom steel plate 222 to the surrounding ultra-high performance concrete, realizing the coordinated deformation of the steel plate and ultra-high performance concrete. The ultra-high performance concrete rib plate avoids the problems of fatigue cracking and insufficient local stiffness leading to easy pavement damage in traditional orthotropic steel bridge decks. At the same time, its self-weight is only 50% of that of concrete bridge decks, effectively solving the problem of excessive self-weight of conventional concrete bridge decks and significantly improving the bridge's spanning capacity.

[0075] The ribbed composite structure is a longitudinally stressed structure. A longitudinal rib 221 with a width of 0.2 to 0.4 m is arranged every 0.6 to 1 m in the transverse direction. The bottom of the longitudinal rib 221 is provided with a rib bottom steel plate 222 (which is welded with shear studs and the ultra-high performance concrete of the longitudinal rib 221 to share the load). A transverse rib 224 is provided every 1 to 2 wavelengths of the corrugated steel web in the longitudinal direction (and is arranged at both ends of the beam segment) to coordinate the load on the longitudinal rib 221. At the same time, the transverse rib 224 makes it easier to arrange the dry joint connection structure.

[0076] The ends of the second type of beam segment 20 are provided with a second joint structure. The second joint structure includes a second reserved channel 240 for the prestressed tendons 325 to pass through and a second shear key (not shown in the figure). In two adjacent second type of beam segments 20, the second protruding shear key on the end face of one second type of beam segment 20 and the second recessed shear groove (not shown in the figure) on the end face of the other second type of beam segment 20 cooperate with each other, and the gap between the second protruding shear key and the second recessed shear groove is filled with joint adhesive. The convex and concave engagement of the second shear key and the second recessed shear groove, combined with the bonding of the joint adhesive, forms a dual shear resistance mechanism, providing a reliable structural foundation for the segmental prefabrication and assembly construction of the corrugated steel web steel channel composite beam.

[0077] In the area of ​​the ultra-high performance concrete composite roof slab 220, a second reserved channel 240 and a second shear key are provided for the prestressed tendons 325 to pass through. Adjacent second-type beam segments 20 are precisely positioned through the convex-concave fit of the second raised shear key and the second recessed shear groove. The gap is filled with epoxy resin joint adhesive to form an adhesive + mechanical interlocking connection. In the area of ​​the steel base plate 210, a butt bevel is reserved on the end face of the steel base plate 210, allowing adjacent second-type beam segments 20 to be connected by full penetration butt welding after assembly. In the web area, a butt bevel is reserved on the end face of the second corrugated steel web 230, which can also be connected by butt welding, thus enabling the assembly of adjacent second-type beam segments 20.

[0078] In a preferred embodiment, the connecting beam segment 30 includes a top plate connecting structure (not shown in the figure), a bottom plate connecting structure (not shown in the figure), and a web connecting structure (not shown in the figure), wherein: The top plate structure includes a connecting steel plate 311 that is sequentially connected to the bottom steel plate 222, a second shear nail 312 fixed to the connecting steel plate 311, and an integrated top plate 313 cast from ordinary concrete and ultra-high performance concrete. The integrated top plate 313 has a third reserved channel 324 pre-embedded in it for the internal prestressed tendons 325 to pass through. The third reserved channel 324 is pre-embedded in the integrated top plate 313 and is arranged along the longitudinal direction of the bridge. Its position corresponds to the first reserved channel 151 and the second reserved channel 240, allowing the internal prestressed tendons 325 arranged continuously along the longitudinal direction of the bridge to pass through. One end of the internal prestressed tendon 325 can be anchored to the end of the first type of beam segment 10, and the other end can be anchored to the end of the second type of beam segment 20.

[0079] Specifically, during on-site assembly, the connecting beam segment 30 is first hoisted into place, and then the second type of beam segment 20 is hoisted to a position adjacent to the connecting beam segment 30, aligning the connecting steel plates 311 in the ultra-high performance concrete composite roof slab 220 of the second type of beam segment 20. The connecting steel plates 311 and the rib bottom steel plates 222 can be butt-welded together using double-sided fillet welds. Second shear studs 312 are welded at intervals to the upper surface of the connecting steel plates 311. After on-site assembly, formwork is erected in the area of ​​the connecting steel plates 311 and the second shear studs 312, and the composite roof slab of ordinary concrete and ultra-high performance concrete is poured in one go. Figure 11As shown, ordinary concrete is poured on the left side of the joint boundary line, and ultra-high performance concrete is poured on the right side, so that the concrete material properties on the left side are the same as those of the first type of beam segment 10, and the concrete material properties on the right side are the same as those of the second type of beam segment 20. This top plate joint structure allows the stress on the rib bottom steel plate 222 in the ultra-high performance concrete composite top plate 220 of the second type of beam segment 20 to be gradually transferred to the cast-in-place concrete through the connecting steel plate 311 and the second shear nail 312, and then to the first concrete top plate 110 of the first type of beam segment 10. This solves the stress concentration problem caused by the sudden change in stiffness when the two different material top plates are directly joined, and effectively avoids the risk of cracking at the joint.

[0080] Preferably, the connecting steel plate 311 within the integrated top plate 313 comprises two parts: one part is located within the ultra-high performance concrete area, while the other part is located within the ordinary concrete area, as specifically... Figure 11 As shown.

[0081] The base plate structure includes a second concrete base plate 314, an outer base plate 315 sequentially connected to the steel base plate 210 of the second type of beam segment 20, multiple rows of first perforated steel plates 316 fixed to the upper surface of the outer base plate 315, a steel end plate 317 disposed at the interface between the ordinary concrete and the ultra-high performance concrete, and a base plate prestressed tendon 318 with one end anchored to the steel end plate 317 and the other end anchored to the adjacent first type of beam segment 10. The first perforated steel plate 316 is partially embedded in the second concrete base plate 314, and a through steel bar 319 is inserted in the first perforated steel plate 316. The steel end plate 317 and the outer base plate 315 are fixedly connected, and the outer base plate 315 extends into the second concrete base plate 314. Preferably, the extension length is not less than 300 mm. The first perforated steel plate 316 is connected to the longitudinal stiffening rib 250 of the base plate to form a continuous structure, and the steel end plate 317 has a slot for the first perforated steel plate 316 to pass through.

[0082] Specifically, the outer base plate 315 and the steel base plate 210 of the second type of beam segment 20 can be connected by butt welds. Multiple rows of first perforated steel plates 316 are welded onto the outer base plate 315, with through-bars 319 inserted into the holes. Steel end plates 317 are vertically welded to the ends of the outer base plate 315, and the steel end plates 317 have openings for the prestressed tendons 318 of the base plate to pass through. The second concrete base plate 314 is cast-in-place concrete, enclosing the first perforated steel plates 316 and the through-bars 319. In this base plate joint structure, the first perforated steel plates 316 and the through-bars 319... The reinforcing bar 319 forms a PBL shear key; by tensioning the prestressed tendons 318 of the base plate, the joint surface is under compression. The base plate joint structure solves the problem of discontinuous force transmission and easy cracking of the joint surface when two different materials and different stiffness components, steel base plate 210 and concrete base plate, are directly connected. It realizes a reliable force transmission path for steel base plate 210, outer base plate 315, first perforated steel plate 316, through reinforcing bar 319, and second concrete base plate 314. At the same time, the crack resistance is further enhanced by actively compressing the prestressed tendons 318 of the base plate.

[0083] The web plate connection structure includes butt welding, foot welding or bolt welding connection for connecting the first corrugated steel web 130 and the second corrugated steel web 230, and Twin-PBL connector 323 or angle steel connector 321 for connecting the third corrugated steel web 322 of the web plate connection structure with the integrated top plate 313 and the second concrete bottom plate 314.

[0084] The web-plate joint structure enables the longitudinal shear force of the web to be continuously transferred to the top and bottom plates, forming a complete combined action, which solves the engineering problem of discontinuous force transmission path of the web between beam segments with different structural forms.

[0085] Furthermore, in the combined beam segment 30: The third corrugated steel web 322 of the web-joint structure is integrally formed in the factory and welded to the steel end plate 317 at the web height change point. It is also connected to the second concrete base plate 314 through the second perforated steel plate 320. Integral forming avoids the number of welds and residual stress caused by segmented cutting and splicing, effectively solving the problem of insufficient fatigue durability caused by excessive welds in the web. The web height change point refers to the position in the joint beam segment 30 where the web height is the same as the first type of beam segment 10 and transitions to the same web height as the second type of beam segment 20. A web height change point is set inside the joint beam segment 30 to make the web height transition smoothly. At the web height change point, the third corrugated steel web 322 and the steel end plate 317 can be welded with double-sided fillet welds, and the weld height is not less than the web thickness. The third corrugated steel web 322 is connected to the second concrete base plate 314 through the second perforated steel plate 320. The second perforated steel plate 320 has a through-bar 319, forming a PBL shear key, which solves the problem of slippage at the interface between the web and the base plate.

[0086] The third corrugated steel web 322 and the second concrete base plate 314 are connected by angle steel connectors 321; the third corrugated steel web 322 and the second concrete base plate 314 are also connected by angle steel connectors 321 to form a double shear resistance mechanism, which further improves the shear bearing capacity.

[0087] The third corrugated steel web 322 is connected to the integrated top plate 313 using a Twin-PBL connector 323. The third corrugated steel web 322 is connected to the integrated top plate 313 using a Twin-PBL connector 323 (i.e., double-row perforated steel plate, a mature component not described in detail), and is embedded in the ordinary concrete area of ​​the integrated top plate 313, which can improve the shear bearing capacity.

[0088] The third corrugated steel web 322 and the first corrugated steel web 130 are connected by butt welding, foot welding or bolt welding. The third corrugated steel web 322 is connected to the second corrugated steel web 230 by a combination of butt welding, foot welding, or bolt welding. The third corrugated steel web 322 can also be butt welded to the first corrugated steel web 130 and the second corrugated steel web 230, with a weld grade of Class I, to ensure continuous force transmission.

[0089] Through the above-described connection, the web plate joint structure forms a complete longitudinal force transmission system, systematically solving engineering problems such as discontinuous force transmission between beam segments of different structural forms, weak shear resistance at the interface, stress concentration, and insufficient fatigue durability.

[0090] The above are merely preferred embodiments of the present invention and do not limit the scope of protection of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention’s specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the scope of patent protection of the present invention.

Claims

1. A method for asymmetric balanced cantilever construction of a corrugated steel web hybrid beam bridge, characterized in that, Includes the following steps: S1, the construction pier and 0# beam segment, several Class I beam segments are symmetrically cantilevered and assembled on both sides of the 0# beam segment; each Class I beam segment includes a first concrete top slab, a first concrete bottom slab and a first corrugated steel web; S2, continue the symmetrical cantilever assembly of the first type of beam segment on the side span to the last segment before the side span closure, and at the same time complete the assembly of the connecting beam segment on the middle span. After the assembly of each first type of beam segment is completed, the internal prestressed tendons of the corresponding beam segment are tensioned. S3, construct the cast-in-place section and the precast support section of the beam end of the side span, and apply the first-stage ballast inside the box of the cast-in-place section and the precast support section; wherein, the first-stage ballast is a ballast permanently fixed to the side span; S4, complete the closure of the side span, form a stable side span structure, and retain the temporary support on the pier top; S5, the second type of beam segment is assembled by single-sided cantilever on the main span side; wherein, the second type of beam segment includes a steel bottom plate, an ultra-high performance concrete composite top plate and a second corrugated steel web; S6. During the single-sided cantilever assembly process on the main span, the unbalanced bending moment at the pier top is monitored in real time, and secondary counterweight is dynamically applied or adjusted on the top of the side span beam based on the monitoring data to keep the bending moment at the pier top within the design allowable range; wherein, the secondary counterweight is an adjustable counterweight. S7, the mid-span closure was completed, the temporary supports on the pier tops were released, the external prestressing tendons of the entire bridge were tensioned, and the system conversion was completed.

2. The asymmetric balanced cantilever construction method for corrugated steel web hybrid beam bridge according to claim 1, characterized in that, In step S3: The prefabricated support section of the side span is a prefabricated enclosed box structure, and the top plate of the prefabricated enclosed box structure is reserved with a grouting port; The first-stage weight-bearing includes barite concrete injected into the box-shaped structure of the precast support section through the grouting port, and barite concrete poured into the box-shaped structure of the cast-in-place beam end section; wherein the unit weight of the barite concrete is ≥35kN / m³. 3 The strength grade is C30 to C40; The barite concrete is pressed or poured and then cured to more than 80% of its design strength to fill part of the internal space of the box body of the precast support section and the cast-in-place beam end section.

3. The asymmetric balanced cantilever construction method for corrugated steel web hybrid beam bridge according to claim 2, characterized in that, The amount of barite concrete used is obtained through the following steps: Establish a finite element model that includes bridge piers, beam segment #0, type I beam segment, combined beam segment, type II beam segment, cast-in-place beam end segment, precast support segment, side span closure segment, mid span closure segment, temporary support on pier top, and permanent support. Based on the finite element model, the entire process of single-sided cantilever splicing of the second type of beam segment on the main span after the side span is closed is simulated, and the pier top bending moment at each construction stage is calculated. The proportion of unbalanced bending moment borne by the first-phase counterweight is determined based on the side-to-middle span ratio; wherein, the proportion increases as the side-to-middle span ratio decreases; By adjusting the total amount of the first-phase load through trial calculations, the unbalanced bending moment borne by the first-phase load is made to meet the proportional requirements, and the bending moment at the top of the pier at each construction stage under the combined action of the first-phase load and the second-phase load does not exceed the maximum unbalanced bending moment allowed by the design; wherein, the second-phase load is simulated in a way that can be dynamically adjusted during the construction process. The minimum total weight of the first phase that meets the conditions is taken as the amount of barite concrete used.

4. The asymmetric balanced cantilever construction method for corrugated steel web hybrid beam bridge according to claim 1, characterized in that, Step S6 includes the following steps: S61, before pouring concrete for the cast-in-place section at the beam end of the side span, an anchoring steel plate is pre-embedded on the top of the cast-in-place section at the beam end and a positioning tenon is welded onto the anchoring steel plate. The anchoring steel plate is provided with bolt holes and embedded with anchoring steel bars. When the support prefabrication section of the side span is prefabricated, an anchoring steel plate is pre-embedded on the top of the beam of the support prefabrication section and a positioning tenon is welded onto the anchoring steel plate. The anchoring steel plate is provided with bolt holes and embedded with anchoring steel bars. S62, a precast reinforced concrete counterweight block, wherein the bottom of the reinforced concrete counterweight block is provided with a positioning groove that mates with the positioning tenon, and a vertical bolt hole that passes through the reinforced concrete counterweight block, and the reinforced concrete counterweight block is connected to the bolt hole of the anchoring steel plate by bolts passing through the vertical bolt hole. S63, during the single-sided cantilever splicing of the second type of beam segment in step S5, the unbalanced bending moment at the top of the pier is monitored in real time by strain sensors embedded on both sides of the pier top and at the root bottom of beam segment #0. S64. When the monitored bending moment at the pier top reaches 60% of the maximum unbalanced bending moment allowed by the design, the installation position of the reinforced concrete counterweight on the top of the side span beam is determined according to the weight of the reinforced concrete counterweight and the bending moment to be offset. The reinforced concrete counterweight is hoisted and installed at the installation position to reduce the bending moment at the pier top to below 30% of the maximum unbalanced bending moment allowed by the design. S65. Repeat steps S63 to S64 based on real-time monitoring data until all second-class beam segments are assembled.

5. The asymmetric balanced cantilever construction method for corrugated steel web hybrid beam bridge according to claim 4, characterized in that, Step S64, which determines the installation position of the reinforced concrete counterweight on the top of the side span beam based on the weight of the reinforced concrete counterweight and the bending moment to be offset, includes the following steps: S641, Calculate the required moment to be offset based on the difference between the monitored pier top bending moment and 30% of the maximum unbalanced bending moment allowed by the design. S642, Based on the weight of the reinforced concrete counterweight and the bending moment value to be offset, calculate the lever arm length of the reinforced concrete counterweight from the top of the pier using the principle of moment balance. S643, Based on the lever arm length and the geometric dimensions of the top of the side span beam, determine the longitudinal installation position of the reinforced concrete counterweight block on the top of the side span beam.

6. The asymmetric balanced cantilever construction method for corrugated steel web hybrid beam bridge according to claim 1, characterized in that, Step S4 includes the following steps: S41, after the completion of the first phase of counterweight construction, install the rigid connection components of the side span closure section, hoist the corrugated steel web of the side span closure beam section, tie the top and bottom plate reinforcement, and pour the closure section concrete; S42. After the concrete strength of the closure section reaches 90% of the design strength, the prestressed tendons in the bottom slab are tensioned to form an integral whole, thus completing the closure of the side span. S43, after the side span is closed, the temporary support on the pier top is retained to maintain the temporary fixed state between the 0# beam segment and the pier. The temporary support on the pier top is used to bear the unbalanced bending moment during the subsequent single-sided cantilever splicing of the second type of beam segment on the main span.

7. The asymmetric balanced cantilever construction method for corrugated steel web hybrid beam bridge according to claim 1, characterized in that, Step S7 includes the following steps: S71. After completing the single-sided cantilever splicing of all the second-class beam segments, the steel channel beam of the mid-span closure segment is hoisted, the steel channel beam is connected to the steel bottom plate and the second corrugated steel web of the adjacent second-class beam segment, the top plate joint concrete is poured, the top plate prestressing tendons of the mid-span closure segment are tensioned, and the mid-span closure is completed. S72, after the mid-span is closed, the temporary supports on the pier tops are removed, and the weight of the beam is transferred to the permanent supports; S73, after removing the temporary supports on the pier top, tension the external prestressed tendons of the entire bridge to complete the system conversion.

8. The asymmetric balanced cantilever construction method for corrugated steel web hybrid beam bridge according to claim 1, characterized in that, Step S1 includes the following steps: S11, a temporary support is set on the top of the pier, and a permanent support installation position is reserved. A support frame is erected on the temporary support, and the 0# beam segment is poured to form a temporary connection between the 0# beam segment and the pier. S12, the first type of beam segment is symmetrically cantilevered and assembled on both sides of the 0# beam segment. After each first type of beam segment is assembled, the corresponding internal prestressed tendons of the first type of beam segment are tensioned so that the assembled first type of beam segment forms an integral load-bearing structure, and the number of assembled segments and the tensioning progress on both sides are kept symmetrical so that the load on both sides of the pier is balanced.

9. The asymmetric balanced cantilever construction method for corrugated steel web hybrid beam bridge according to claim 4, characterized in that, The reinforced concrete ballast blocks are a multi-block stacked structure, and the reinforced concrete ballast blocks of adjacent layers can be detachably connected.

10. The asymmetric balanced cantilever construction method for corrugated steel web hybrid beam bridge according to claim 4, characterized in that, The strain sensor includes vibrating wire strain gauges embedded on both sides of the pier top and at the root bottom of beam segment #0, and the sampling frequency of the strain sensor is not less than 1Hz.

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