A bridge substructure with ultra-long span and ultra-long cantilever and its design method

Abstract

The present invention relates to a bridge substructure and design method for an ultra-long span and ultra-long cantilever. The method comprises a steel tube concrete-filled bridge pier comprising steel tubes and concrete; a prestressed steel box concrete cap beam comprising a steel box and concrete; a tilted steel box bottom plate at the cantilever, with a mid-span height of H and an end section height of 0.3H to 0.4H; a plurality of prestressed steel strands disposed at the top and bottom of the steel box, with the top prestressed steel strand disposed within the end section height range and the bottom prestressed steel strand disposed within a 0.25H upward section height of the bottom plate; the bottom of the cantilever bottom plate forming a broken line for anchoring the prestressed steel strands; a pier top joint disposed at the bottom of the steel box, which is inserted into the top of the steel tube, with a reserved height of at least 0.5H above the top of the steel tube left uncast. After the steel box is installed at the top of the steel tube concrete-filled bridge pier, the bottom plate is welded to the steel tube at contact, and then concrete is poured in the reserved area above the steel tube. This method is highly effective.

Description

Technical Field

[0001] The present invention relates to the technical field of bridges, and in particular to a bridge substructure with an ultra-large span and ultra-long cantilever and a design method thereof. Background Art

[0002] When the width of the bridge superstructure reaches a certain level, the substructure is often divided into sections corresponding to the bridge width in order to support the bridge superstructure. However, the divided substructure has the problem of large material consumption and large space occupied under the bridge. At the same time, when a full-width substructure is used, the steel substructure may have insufficient rigidity and high material consumption, and the structure needs to be equipped with a large number of stiffening ribs to meet the load requirements. When a concrete structure is used, there are problems such as excessive use of prestressed steel strands, poor seismic performance, and excessive structural size. Construction requires the erection of a large number of supports, the quality of the finished product is difficult to guarantee, and the bulky appearance affects the visual effect of traffic under the bridge.

[0003] In the existing technology, reinforced concrete or prestressed reinforced concrete cap beam materials are brittle structures with poor seismic performance and ductility. At the same time, the erection of brackets for concrete cap beams seriously affects the traffic under the bridge and the construction progress. The use of assembled construction faces the problems of segmentation, many joints, heavy lifting weight, and high overall unit price. In the existing technology, the overall rigidity of the steel cap beam structure is small. In order to ensure that it can bear the weight of the upper structure, a large amount of steel is required and the reinforcement structure is complicated. The construction of large-span steel box cap beams requires large-scale lifting equipment or the installation of temporary piers, which makes construction difficult. In the scheme of using prestressed steel box concrete cap beams in the existing technology, only prestressed steel strands are arranged on the lower part of the cross section, and the cross-sectional dimensions of the structure are not optimized. When it is used in an environment with ultra-large spans and ultra-long cantilevers, the structural dimensions are larger and the material consumption is greater. Summary of the Invention

[0004] The purpose of the present invention is to provide a bridge substructure and design method with an ultra-large span and ultra-long cantilever to address the problems existing in the prior art.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

[0006] A design method for the substructure of a bridge with an ultra-long span and ultra-long cantilever, comprising:

[0007] Concrete-filled steel tube piers consist of steel tubes and concrete poured inside them, with no steel bars installed inside.

[0008] The prestressed steel box concrete cap beam includes a steel box and concrete poured inside it, without any steel bars;

[0009] The steel box is narrowed at the cantilever arm, and the bottom plate of the steel box at the cantilever arm is inclined. The mid-span height of the steel box is set to H, and the end section height of the steel box is set to 0.3H-0.4H.

[0010] A plurality of prestressed steel strands are respectively arranged at the top and bottom of the steel box. The prestressed steel strands at the top are arranged within the height range of the end section, and the prestressed steel strands at the bottom are arranged within the height range of 0.25H of the upward section of the bottom plate. The bottom of the bottom plate at the cantilever is a broken line portion, and the broken line portion is used to anchor the prestressed steel strands at the bottom.

[0011] A pier top joint is provided at the bottom of the steel box, and the pier top joint is used to insert the top of the steel pipe. When the steel pipe is cast, a height range of at least 0.5H is reserved at the top without casting. After the steel box is installed on the top of the steel tube concrete pier, the contact part between the bottom plate and the steel pipe is welded, and then concrete is cast in the reserved part of the top of the steel pipe.

[0012] In this application, the span refers to the width of the prestressed steel box concrete cap beam. When the total number of lanes acting on the prestressed steel box concrete cap beam is greater than or equal to 8 lanes, it is an extra-large span. When the number of lanes acting on the cantilever is greater than or equal to 2 lanes, it is an extra-long cantilever.

[0013] The design method of the bridge substructure with an ultra-large span and ultra-long cantilever described in the present invention is adopted. The steel box and the steel pipe are connected by welding and the concrete pouring of the pier top joint. No connecting channel is provided at the bottom of the steel box. While the connection is reliable, it is ensured that no leakage or the like occurs during the pouring of the prestressed steel box concrete cap beam. The bottom plate is obliquely arranged at the cantilever to reduce the cross-sectional height dimension at the cantilever, taking into account both force and material saving. At the same time, the physical guiding effect of the oblique bottom plate is utilized to ensure smooth pouring of concrete in the steel box and avoid the situation of loose pouring caused by local congestion. ; The fold line portion provided at the root of the cantilever is used as a reaction force tensioning anchor plate, which is convenient for tensioning and anchoring the prestressed steel bundle at the bottom of the section, avoiding unnecessary structural welding and flame cutting work of the bottom plate; the high bearing capacity and good seismic performance of the steel box and the steel pipe structure are utilized to achieve material savings, and the structural size is smaller than that of the concrete cap beam, which can achieve super-large spans and super-long cantilevers, meeting the overall design requirements of the bridge substructure; by arranging the prestressed steel bundle in the upper area of ​​the steel box end closure plate, the cantilever stress of the cantilever section is improved, and the stress condition of the upper section at the pier support position is improved.

[0014] Preferably, the vertical spacing of the prestressed steel strands is set to d, the broken line portion is in a stepped shape, the height of each step is set to 3d-5d, and the length of each step is set to 10d-15d.

[0015] Preferably, a plurality of open stiffening ribs are longitudinally arranged in the prestressed steel box concrete cap beam, a portion of the open stiffening ribs are arranged throughout the entire length, and the rest are arranged locally, and no partition plates or internal transverse partitions are arranged in the prestressed steel box concrete cap beam.

[0016] Preferably, the contact portion between the base plate and the steel pipe is welded by multi-layer penetration welding. After welding is completed, concrete is poured into the gap portion where the steel pipe mouth exceeds the width of the base plate to connect the steel pipe and the steel box and form the steel tube concrete pier.

[0017] Preferably, concrete is poured in the steel box to form the prestressed steel box concrete cap beam. After the concrete hardens to the design strength, the prestressed steel strands anchored at both ends of the steel box are tensioned to complete the structural construction, and the combined structure begins to bear the stress in a coordinated manner.

[0018] Preferably, the pier top joint adopts several stiffening plates welded to the steel box, some of the stiffening plates are welded to the bottom plate, and some of the stiffening plates are welded to the web and bottom plate of the steel box at the same time, and the part of the stiffening plate extending into the steel pipe is provided with several through holes.

[0019] Preferably, a number of annular stirrups are welded at intervals inside the steel pipe to ensure the roundness of the steel pipe during processing and to prevent deformation during transportation.

[0020] Preferably, a pier-pile joint is provided at the bottom of the concrete-filled steel tube pier, and the concrete-filled steel tube pier is connected to the pile top via the pier-pile joint.

[0021] Preferably, the steel tube concrete pier and the prestressed steel box concrete cap beam are cast and formed by using self-compacting concrete.

[0022] The present invention also provides a bridge substructure with an ultra-large span and ultra-long cantilever, which is designed and manufactured using the design method for a bridge substructure with an ultra-large span and ultra-long cantilever as described in any of the above items. The bridge substructure includes the steel tube concrete pier and the prestressed steel box concrete cap beam connected thereto.

[0023] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0024] 1. In the design method for a bridge substructure with an ultra-long span and ultra-long cantilever according to the present invention, the steel box and the steel pipe are connected by welding and the pier top joint is concrete poured. No connection channel is provided at the bottom of the steel box. This ensures a reliable connection and prevents leakage of concrete during the pouring of the prestressed steel box concrete cap beam.

[0025] 2. The design method for the substructure of a bridge with an ultra-long span and ultra-long cantilever according to the present invention utilizes an oblique arrangement of the bottom plate at the cantilever to reduce the cross-sectional height of the cantilever, taking into account both force and material conservation. Furthermore, the physical guidance function of the oblique bottom plate is utilized to ensure smooth pouring of concrete in the steel box, avoiding local congestion and incomplete pouring.

[0026] 3. The design method for the substructure of a bridge with an ultra-long span and ultra-long cantilever according to the present invention utilizes the folded portion provided at the base of the cantilever to also serve as a reaction force tensioning anchor plate, thereby facilitating the tensioning and anchoring of the prestressed steel strands at the bottom of the cross section and avoiding unnecessary structural welding and flame cutting work on the bottom plate.

[0027] 4. The design method for a bridge substructure with an ultra-large span and ultra-long cantilever, described in the present invention, utilizes the high load-bearing capacity and good seismic performance of the steel box and steel pipe structure to achieve material savings. The structure is smaller in size than a concrete cap beam, enabling ultra-large spans and ultra-long cantilevers to meet the overall design requirements of the bridge substructure.

[0028] 5. The design method of the substructure of a bridge with an ultra-large span and ultra-long cantilever described in the present invention improves the cantilever stress of the cantilever section and improves the stress condition of the upper section at the pier support position by arranging the prestressed steel bundles in the upper area of ​​the steel box end cover. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 Schematic diagram of the bridge substructure Figure 1 ;

[0030] Figure 2 This is a schematic elevation diagram of the prestressed steel box concrete cap beam;

[0031] Figure 3 This is a plan view of the prestressed steel box concrete cap beam;

[0032] Figure 4 Schematic diagram of the bridge substructure Figure 2 ;

[0033] Figure 5 This is a semi-elevation diagram of the prestressed steel box concrete cap beam;

[0034] Figure 6 for Figure 5 A magnified schematic diagram of the middle part;

[0035] Figure 7 for Figure 6 Schematic diagram of the BB cross section;

[0036] Figure 8 This is a schematic diagram of the mid-span section of the prestressed steel box concrete cap beam;

[0037] Figure 9 for Figure 8 Schematic diagram of CC cross section;

[0038] Figure 10 for Figure 8 Middle DD cross-sectional view;

[0039] Figure 11 It is the structural diagram of the pier top joint;

[0040] Figure 12 This is a schematic diagram of the bundle arrangement of the prestressed steel box concrete cap beam for this application;

[0041] Figure 13 This is a schematic diagram of the existing prestressed steel box concrete cap beam layout.

[0042] Markings in the figure: 1-steel tube concrete pier, 11-pier pile joint, 2-prestressed steel box concrete cap beam, 21-pier top joint, 22-bottom plate, 23-broken line, 24-prestressed steel strand, 25-opening stiffening rib. DETAILED DESCRIPTION

[0043] The present invention will be described in detail below with reference to the accompanying drawings.

[0044] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0045] Example 1

[0046] The design method of a bridge substructure with an ultra-long span and ultra-long cantilever according to the present invention comprises:

[0047] like Figure 1 As shown, the steel tube concrete pier 1 includes a steel tube and self-compacting concrete poured therein. No steel bars are provided therein. A number of annular stirrups are welded at intervals inside the steel tube to ensure the roundness of the steel tube during processing and to prevent deformation during transportation. A pier-pile joint 11 is provided at the bottom of the steel tube concrete pier 1, and the steel tube concrete pier 1 is connected to the pile top via the pier-pile joint 11.

[0048] like Figures 1 to 3 As shown, the prestressed steel box concrete cap beam 2 includes a steel box and self-compacting concrete poured therein, without any steel bars.

[0049] like Figure 4 and Figure 5As shown, the steel box is narrowed at the cantilever, and the bottom plate 22 of the steel box at the cantilever is inclined. The mid-span height of the steel box is set to H, and the end section height of the steel box is set to 0.3H-0.4H according to the length of the cantilever.

[0050] like Figures 4 to 7 As shown, a plurality of prestressed steel bundles 24 are respectively arranged at the top and bottom of the steel box. The prestressed steel bundles 24 at the top are arranged within the height range of the end section, and the prestressed steel bundles 24 at the bottom are arranged within the upward section height range of 0.25H of the bottom plate 22. They are disconnected at the oblique bottom plate 22 at the cantilever. The bottom of the bottom plate 22 at the cantilever is a broken line portion 23. The broken line portion 23 is used to provide an anchoring plane for the tensioning anchoring of the prestressed steel bundles 24 at the bottom, so as to facilitate the pre-tensioning construction.

[0051] like Figure 6 and Figure 7 As shown, the vertical spacing of the prestressed steel strands 24 is set to d, the fold line portion 23 is in a stepped shape, the height of each step is set to 3d-5d, the length of each step is set to 10d-15d, and the width of the fold line portion 23 is consistent with the width of the bottom plate 22 in the remaining parts.

[0052] like Figures 8 to 10 As shown, a number of open stiffening ribs 25 are longitudinally arranged in the prestressed steel box concrete cap beam 2, a part of the open stiffening ribs 25 are arranged throughout the length, and the rest are arranged locally. No partition plates or internal cross partitions are arranged in the prestressed steel box concrete cap beam 2.

[0053] like Figure 1 and Figure 11 As shown, a pier top joint 21 is provided at the bottom of the steel box, and the pier top joint 21 is used to insert the top of the steel pipe. The pier top joint 21 adopts a plurality of stiffening plates welded to the steel box, some of the stiffening plates are welded to the bottom plate 22, and some of the stiffening plates are welded to the web of the steel box and the bottom plate 22 at the same time. When the steel pipe is cast, a height range of at least 0.5H is reserved at the top without casting. After the steel box is installed on the top of the steel tube concrete pier 1, the contact part of the bottom plate 22 and the steel pipe is multi-layered through-penetration welded using a small welding rod and a low current. After the welding is completed, the concrete of the reserved part of the top of the steel pipe is cast from the gap part where the steel pipe mouth exceeds the width of the bottom plate 22. After the concrete is formed, the steel pipe and the steel box are completely connected, and the steel tube concrete pier 1 is formed. The part of the stiffening plate extending into the steel pipe is provided with a plurality of through holes.

[0054] Concrete is poured in the steel box to form the prestressed steel box concrete cap beam 2. After the concrete hardens to reach the designed strength, the prestressed steel bundles 24 anchored at both ends of the steel box are tensioned to complete the structural construction, and the combined structure begins to bear the force in a coordinated manner.

[0055] The prestressed steel box concrete cap beam 2 in this embodiment is optimized in terms of the arrangement position and cross-sectional dimensions of the prestressed steel strands 24 in combination with the stress behavior of the cap beam. Compared with the arrangement of the prestressed steel box concrete cap beam in the existing scheme, Figure 12 and Figure 13 The optimization details are shown in Table 1.

[0056] Table 1. Comparison of structural details of prestressed steel box concrete cap beams

[0057]

[0058] The steel pipes are welded and processed in the factory, and are installed as a whole after being transported to the site, and self-compacting concrete is poured into the pipes; the steel boxes are welded and processed in the factory, and the prestressed steel bundles 24 are installed and arranged. The steel boxes are used as prestressed tensioning reaction bases. By controlling the weight of the steel boxes, they can be hoisted as a whole to the top of the pier after processing in the factory. After a small amount of welding operations, self-compacting concrete is poured into the boxes. After the concrete reaches the required strength, it is tensioned to form an integral structure.

[0059] The present embodiment describes a design method for a bridge substructure with an ultra-large span and ultra-long cantilever arm. The steel box and the steel pipe are connected by welding and the pier top joint 21 is poured with concrete. No connection channel is provided at the bottom of the steel box. While the connection is reliable, it is ensured that no leakage or the like occurs during the pouring of the prestressed steel box concrete cap beam 2. The bottom plate 22 is obliquely arranged at the cantilever arm to reduce the cross-sectional height dimension of the cantilever arm, taking into account both force and material conservation. The physical guiding effect of the oblique bottom plate 22 is utilized to ensure smooth pouring of concrete in the steel box and avoid the situation of loose pouring caused by local congestion. The fold line portion 23 provided at the root of the cantilever is used as a reaction force tensioning anchor plate, which is convenient for tensioning and anchoring the prestressed steel bundle 24 at the bottom of the section, avoiding unnecessary structural welding and flame cutting work of the bottom plate 22; utilizing the high bearing capacity and good seismic performance of the steel box and the steel pipe structure, material consumption can be saved, and the structural size is smaller than that of the concrete cap beam, which can achieve super-large span and super-long cantilever, meeting the overall design requirements of the bridge substructure; by arranging the prestressed steel bundle 24 in the upper area of ​​the steel box end cover, the cantilever stress of the cantilever section is improved, and the stress condition of the upper section at the pier support position is improved.

[0060] Example 2

[0061] like Figures 1 to 12As shown, the substructure of a bridge with an ultra-large span and ultra-long cantilever described in the present invention is designed and manufactured using the design method of the substructure of a bridge with an ultra-large span and ultra-long cantilever described in Example 1. The substructure of the bridge includes the steel tube concrete pier 1 and the prestressed steel box concrete cap beam 2 connected thereto.

[0062] The present embodiment describes a bridge substructure with an ultra-large span and ultra-long cantilever arm. The steel box and the steel pipe are connected by welding and the pier top joint 21 is poured with concrete. No connection channel is provided at the bottom of the steel box. While the connection is reliable, it is ensured that no leakage or the like occurs during the pouring of the prestressed steel box concrete cap beam 2. The bottom plate 22 is obliquely arranged at the cantilever arm to reduce the cross-sectional height dimension at the cantilever arm, taking into account both force and material saving. The physical guiding effect of the oblique bottom plate 22 is utilized to ensure smooth pouring of concrete in the steel box and avoid the situation of loose pouring caused by local congestion. The fold line portion 23 provided at the root of the cantilever also serves as a reaction force tensioning anchor plate, which is convenient for the tensioning and anchoring of the prestressed steel bundle 24 at the bottom of the section, avoiding unnecessary structural welding and flame cutting work of the bottom plate 22; utilizing the high bearing capacity and good seismic performance of the steel box and the steel pipe structure, material consumption is saved, and the structural size is smaller than that of the concrete cap beam, which can achieve super-large span and super-long cantilever, meeting the overall design requirements of the bridge substructure; by arranging the prestressed steel bundle 24 in the upper area of ​​the steel box end cover, the cantilever stress of the cantilever section is improved, and the stress condition of the upper section at the pier support position is improved.

[0063] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A design method for the substructure of a bridge with an ultra-large span and ultra-long cantilever, characterized in that: include: The steel tube concrete bridge pier (1) comprises a steel tube and concrete poured therein, without any steel bars arranged therein; The prestressed steel box concrete cap beam (2) comprises a steel box and concrete poured therein, with no steel bars arranged therein; The steel box is narrowed at the cantilever, and the bottom plate (22) of the steel box at the cantilever is inclined, the mid-span height of the steel box is set to H, and the end section height of the steel box is set to 0.3H-0.4H; A plurality of prestressed steel bundles (24) are respectively arranged at the top and bottom of the steel box, the prestressed steel bundles (24) at the top are arranged within the height range of the end section, and the prestressed steel bundles (24) at the bottom are arranged within the height range of 0.25H of the upward section of the bottom plate (22), and the bottom of the bottom plate (22) at the cantilever is a broken line portion (23), and the broken line portion (23) is used for anchoring the prestressed steel bundles (24) at the bottom; A pier top joint (21) is provided at the bottom of the steel box, and the pier top joint (21) is used to insert the top of the steel pipe. When the steel pipe is cast, a height range of at least 0.5H is reserved at the top for non-casting. After the steel box is installed on the top of the steel tube concrete pier (1), the bottom plate (22) is welded to the contact portion of the steel pipe, and then concrete is cast at the reserved portion of the top of the steel pipe. The vertical spacing of the prestressed steel strands (24) is set to d, the folded line portion (23) is in a stepped shape, the height of each step is set to 3d-5d, and the length of each step is set to 10d-15d; A pier-pile joint (11) is provided at the bottom of the steel tube concrete pier (1), and the steel tube concrete pier (1) is connected to the pile top via the pier-pile joint (11).

2. The design method for the substructure of a bridge with an ultra-long span and ultra-long cantilever according to claim 1 is characterized in that: A plurality of opening stiffening ribs (25) are longitudinally arranged in the prestressed steel box concrete cap beam (2), a portion of the opening stiffening ribs (25) are arranged throughout the entire length, and the rest are arranged locally. No partition plates or internal transverse partitions are arranged in the prestressed steel box concrete cap beam (2).

3. The design method for the substructure of a bridge with an ultra-long span and ultra-long cantilever according to claim 1 is characterized in that: The contact portion between the bottom plate (22) and the steel pipe is welded by multi-layer penetration welding. After welding is completed, concrete is poured into the gap portion where the mouth of the steel pipe exceeds the width of the bottom plate (22), connecting the steel pipe and the steel box and forming the steel tube concrete bridge pier (1).

4. The design method for the substructure of a bridge with an ultra-long span and ultra-long cantilever according to claim 1 is characterized in that: Concrete is poured in the steel box to form the prestressed steel box concrete cap beam (2), and after the concrete hardens to reach the designed strength, the prestressed steel bundles (24) anchored at both ends of the steel box are tensioned.

5. The design method of the bridge substructure with an ultra-long span and ultra-long cantilever according to claim 1 is characterized in that: The pier top joint (21) adopts a plurality of stiffening plates welded to the steel box, some of the stiffening plates are welded to the bottom plate (22), and some of the stiffening plates are welded to the web of the steel box and the bottom plate (22) at the same time, and a plurality of through holes are provided in the portion of the stiffening plate extending into the steel pipe.

6. The design method for the substructure of a bridge with an ultra-long span and ultra-long cantilever according to claim 1 is characterized in that: A plurality of annular stirrups are welded at intervals inside the steel pipe.

7. The design method for the substructure of a bridge with an ultra-long span and ultra-long cantilever according to any one of claims 1 to 6, characterized in that: The steel tube concrete pier (1) and the prestressed steel box concrete cap beam (2) are cast and formed using self-compacting concrete.

8. A bridge substructure with an ultra-large span and ultra-long cantilever, characterized in that: The bridge substructure with an ultra-large span and ultra-long cantilever is designed and manufactured using the design method of any one of claims 1 to 7, and the bridge substructure includes the steel tube concrete pier (1) and the prestressed steel box concrete cap beam (2) connected thereto.

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