Construction method of large cantilever prestress cast-in-place cover beam

Abstract

The construction method comprises the following steps that a bearing platform and a pier column are constructed, a high-strength pin rod, a bracket and a sand top are installed on the side edge of the pier column, and an attached support is placed on the sand top; steel pipe columns are installed on the bearing platforms, and suspenders are arranged among the steel pipe columns, the top ends of the steel pipe columns and the main beam sections for tensioning and pre-tightening treatment; and the self-propelled large-cantilever bent cap tensioning hanging basket is assembled and then installed, and secondary tensioning operation of the large-cantilever prestressed bent cap at different positions is carried out. The construction method has the beneficial effects that the holes are reserved in the pier column structure, the high-strength pin rods are installed, meanwhile, the attached support is modularly manufactured and connected and installed, and compared with a traditional supporting system, the construction method is easy and convenient to operate and high in construction safety, the construction efficiency is effectively improved, and the overall construction quality of the support can be effectively improved.

Description

Technical Field

[0001] The invention belongs to the field of bridge cap beam construction, and in particular relates to a construction method of a large cantilever prestressed cast-in-place cap beam. Background Art

[0002] The development of urban viaducts has promoted the development of the local economy and met the travel needs of the people in the area. However, due to the limitations of the surrounding environment, traffic requirements and landscape requirements, there are high requirements for the lower spatial structure of the bridge. The large cantilever prestressed cap beam has a simple and generous shape and can save space under the bridge, so it is widely used in urban viaducts. At present, there are many difficulties in the construction of large cantilever cap beams. Compared with general concrete cap beams, the stress conditions of prestressed large cantilever cap beams are more complicated and require a large number of temporary structures during construction.

[0003] The traditional large cantilever cap beam construction process often faces problems such as insufficient support frame stability, complex support installation and removal, and low secondary tensioning construction efficiency, which not only increases the project cost, but also may cause construction progress delays and safety risks. Therefore, it is of great significance to study the large cantilever prestressed cast-in-place cap beam and its construction method. Summary of the invention

[0004] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a construction method for a large cantilever prestressed cast-in-place cap beam.

[0005] The construction method of this large cantilever prestressed cast-in-place cap beam includes the following construction steps:

[0006] S1. Construct the cap and pier, install high-strength pins, brackets and sand tops on the sides of the piers, and place the attached bracket on the sand top;

[0007] S2. Splice the distribution beam and the patterned steel plate to form an integrated module, and hoist the integrated module above the attached bracket;

[0008] S3. Install steel pipe columns on the cap, and set hangers between the top of the steel pipe columns and the main beam segments for tensioning and pre-tightening.

[0009] S4. Assemble the self-propelled large cantilever cap beam tensioning hanging basket and install it to carry out secondary tensioning operation of large cantilever prestressed cap beams at different positions.

[0010] Preferably, in step S1, after the construction of the foundation is completed, the pier is constructed first, and a high-strength pin installation hole is reserved at a specified position of the pier. When the overall construction of the pier is completed, the high-strength pin, corbel and sand top components are installed, and then the attached bracket is assembled, and then the attached bracket is hoisted and installed, and the whole is placed on the sand top.

[0011] Preferably, the attached bracket includes a main beam segment, a cantilever beam segment, a steel diagonal brace, a longitudinal scissors brace and an internal support. The main beam segment and the cantilever beam segment are connected via a flange interface. A steel diagonal brace is provided at the bottom of the cantilever beam segment to connect with the main beam segment. The bottom of the steel diagonal brace is fixed to the flange interface on the main beam segment via a bottom plate. A top plate is arranged on the top of the steel diagonal brace and is welded and fixed to the cantilever beam segment. A longitudinal scissors brace is provided between the main beam segments, and an internal support is provided between the cantilever beam segments.

[0012] Preferably, in step S2, the distribution beam and the patterned steel plate on the bracket are divided into several modules and welded and fixed to form an integrated module, the integrated module is hoisted above the attached bracket, and then the distribution beam is connected and fixed to the main beam segment and cantilever beam segment below using U-bolts, and finally, a guardrail is fixed around the distribution beam.

[0013] Preferably, in step S3, the steel pipe columns are first spliced ​​and fixedly installed on the pedestal, the steel pipe column segments are spliced ​​and installed by flanges and bolts, a plurality of column parallel joints and column diagonal braces are arranged on the steel pipe columns in the transverse direction of the bridge, and a channel steel connection system is arranged in the longitudinal direction of the bridge; filling concrete is also arranged on the top of the steel pipe column, a balance beam is arranged on the top of the steel pipe column, and then the bottom of the hanger is fixedly connected with the main beam segment, and the top is fixedly installed with a jack and a foot support through the balance beam, and multiple groups of jacks simultaneously apply loads to tension and pre-tighten the hanger, so that the hanger generates prestress.

[0014] Preferably, in step S4, the self-propelled large cantilever cap beam tensioning basket includes an upper support frame, a ladder, a vertical hanger, an electric drive system, rollers and a bottom platform frame; the upper support frame is provided with four legs and four rollers, and the electric drive system is used to provide power to drive the rollers to move; the bottom platform frame is surrounded by a guard frame, which is connected to the vertical hanger through a diagonal rod; the ladder is vertically arranged between the upper support frame and the bottom platform frame.

[0015] Preferably, in step S4, the upper support frame, ladder, vertical hanger, electric drive system, rollers and bottom platform frame are welded to form a self-propelled large cantilever cap beam tensioning basket, which is then installed on site to the designated position, and corresponding counterweights are placed on the upper support frame, and steel plates are installed on the bottom platform frame. The operator then enters the lower platform via the ladder to perform secondary tensioning operations. After the tensioning construction at the current position is completed, the rollers are driven by the electric drive system to move the tensioning basket to the next construction position.

[0016] The large cantilever prestressed cast-in-place cap beam is obtained by any of the methods described above.

[0017] The beneficial effects of the present invention are:

[0018] 1) The present invention proposes a large cantilever cap beam attached bracket technology, which reserves holes on the pier structure and installs high-strength pins. At the same time, the attached bracket is modularly manufactured, connected and installed. Compared with the traditional support system, it is easy to operate and has high construction safety, which effectively improves the construction efficiency and can effectively improve the overall construction quality of the bracket.

[0019] 2) The present invention proposes an integrated setting technology of distribution beam and patterned steel plate. Before installation, multiple distribution beams and patterned steel plates are divided into several modules and welded and fixed. After the lifting is completed, protective railings are fixed around the distribution beams, which reduces the risk of warping when installing a single distribution beam, increases the overall installation efficiency, and ensures the safety of high-altitude operations.

[0020] 3) The present invention proposes a high-column diagonal-stayed technology, which adopts a high-column diagonal-stayed structure to reinforce the support. The integrity and bearing capacity of the support system are improved by arranging diagonal-stayed hangers and using jacks for pre-tensioning. On the basis of ensuring construction safety, the support system has high convenience and improves the overall construction quality of the high pier column large cantilever prestressed cap beam support system.

[0021] 4) The present invention proposes a self-propelled large cantilever cap beam tensioning hanging basket technology, in which a secondary tensioning operating platform is welded and manufactured in advance in the factory, and an electric drive system is installed in conjunction with rollers to realize the automatic movement capability of the tensioning platform. On the basis of ensuring construction safety, the flexibility of the operating platform is improved and the efficiency of secondary tensioning construction is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the large cantilever cap beam attached bracket technology;

[0023] Figure 2 It is a schematic diagram of the longitudinal arrangement of the attached bracket;

[0024] Figure 3 It is a schematic diagram of the support installation inside the cantilever beam segment;

[0025] Figure 4 It is a schematic diagram of the technology of integrated setting of distribution beam and patterned steel plate;

[0026] Figure 5 It is a schematic diagram of the high column cable-stayed technology;

[0027] Figure 6 It is the side view of the top structure of the steel pipe column;

[0028] Figure 7 It is a schematic diagram of the structure of a self-propelled large cantilever cap beam tensioning hanging basket.

[0029] Explanation of the reference numerals: 1-main beam segment, 2-pier column reinforcement, 3-flange interface, 4-cantilever beam segment, 5-sand top, 6-corbel, 7-cap, 8-high-strength pin, 9-pier, 10-top plate, 11-steel diagonal brace, 12-bottom plate, 13-longitudinal scissor brace, 14-inner support, 15-distribution beam, 16-rail, 17-patterned steel plate, 18-U-bolt, 19-jack, 20-balance beam , 21-foot support, 22-filling concrete, 23-hanging rod, 24-pin, 25-column parallel connection, 26-column diagonal brace, 27-steel pipe column, 28-flange, 29-bolt, 30-channel steel connection system, 31-ladder, 32-vertical hanger, 33-bottom platform frame, 34-enclosure frame, 35-diagonal rod, 36-electric drive system, 37-roller, 38-leg, 39-upper support frame. DETAILED DESCRIPTION

[0030] The present invention is further described below in conjunction with embodiments. The description of the following embodiments is only used to help understand the present invention. It should be noted that for ordinary persons in the art, without departing from the principle of the present invention, the present invention can also be modified in some ways, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

[0031] Embodiment 1

[0032] As an embodiment, the construction method of the large cantilever prestressed cast-in-place cap beam comprises the following construction steps:

[0033] S1. After the construction of the lower pedestal 7 of the large cantilever cap beam is completed, the pier column 9 is constructed first, and the installation hole of the high-strength pin rod 8 is reserved at the designated position of the pier column 9. After the overall construction of the pier column 9 is completed, the high-strength pin rod 8, the bracket 6 and the sand top 5 components are installed. Then, the main beam segment 1, the cantilever beam segment 4, the steel diagonal brace 11, the longitudinal scissors brace 13, the inner support 14 and other components are assembled on the ground to form an attached bracket. Then, the assembled bracket is hoisted and installed, and the bracket is placed on the sand top 5 as a whole. Finally, the installation position, connectivity and overall stability of the bracket are reviewed, and subsequent construction is carried out after meeting the design requirements. In order to facilitate the installation and removal of the bracket, the stroke of the installed sand top 5 is not less than 6cm.

[0034] S2. After the installation of the attached bracket at the bottom of the cap beam is completed, the distribution beam 15 and the patterned steel plate 17 on the bracket are first divided into several modules and welded and fixed. Then the welded distribution beam 15-patterned steel plate 17 integrated module is hoisted to the top of the bracket, and then the distribution beam 15 is connected and fixed with the main beam segment 1 and the cantilever beam segment 4 below using U-bolts 18. Finally, the guardrail 16 is fixed around the distribution beam 15. The length of a single block of the distribution beam 15-patterned steel plate 17 integrated module is controlled to be 3 to 5 meters.

[0035] S3. When the pier 9 is high and the span of the cap beam is large, in order to improve the bearing capacity and ensure safety, a high column cable-stayed structure is used to reinforce the bearing capacity. First, the steel pipe column 27 is spliced ​​and fixedly installed on the pedestal 1, and the stability of the steel pipe column 27 is improved by arranging the column flat joint 25, the column diagonal brace 26, and the channel steel connection system 30. The top is filled with concrete 22 to enhance stability. Then, the bottom of the hanger 23 is fixedly connected to the main beam segment 1, and the top is fixedly installed with the jack 19 and the foot support 21 through the balance beam 20. Finally, the installation position of each component is reviewed, and multiple groups of jacks 19 simultaneously apply loads to the hanger 23 for tensioning and pre-tightening, so that the hanger 23 produces prestress. After meeting the design requirements, the next step of construction can be carried out. The pouring height of the filled concrete 22 at the top of the steel pipe column 27 is not less than 0.4m.

[0036] S4. Before the large cantilever prestressed cap beam is tensioned for the second time, the upper support frame 39, ladder 31, vertical hanger 32, electric drive system 36, roller 37 and bottom platform frame 33 are first welded in the factory to form a self-propelled large cantilever cap beam tensioning hanging basket, which is then installed on site to the designated position, and the corresponding counterweight is placed on the upper support frame 39, and the steel plate is installed on the bottom platform frame 33. Then the operator enters the lower platform through the ladder 31 to perform the secondary tensioning operation. Finally, after the tensioning construction at the current position is completed, the roller 37 is driven by the electric drive system 36 to move the tensioning hanging basket to the next construction position. In order to reduce the shaking of the tensioning hanging basket platform when it is windy, the upper support frame 39 can be firmly connected to the beam body.

[0037] Embodiment 2

[0038] As another embodiment, this embodiment 2 proposes a more specific construction method of a large cantilever prestressed cast-in-place cap beam on the basis of the embodiment 1:

[0039] like Figures 1 to 3 As shown, after the construction of the lower bridge pier 7 is completed, the pier column 9 is constructed and a high-strength pin 8 installation hole is reserved in the pier body. After the construction of the pier column 9 is completed, the high-strength pin 8, the corbel 6, and the sand top 5 components are installed. After the attached bracket is assembled, the bracket is hoisted and installed on the sand top 5 using a lifting device. Finally, the installation of the bracket is measured and verified. After meeting the requirements, the next step of construction is carried out.

[0040] like Figure 2As shown, before the on-site distribution beam 15 is installed, multiple distribution beams 15 and patterned steel plates 17 are welded and fixed in blocks to form a module, and then the distribution beam 15-patterned steel plate 17 integrated module is hoisted and installed on the bracket main beam, and the distribution beam 15 and the lower main beam segment 1 and the cantilever beam segment 4 are fixedly connected using U-bolts 18, and finally the guardrail 16 is installed around the distribution beam 15 for construction protection.

[0041] like Figure 5 and Figure 6 As shown, when the pier 9 is relatively high and the span of the cap beam is large, the steel pipe column 27 is first fixedly installed on the pedestal 7. The steel pipe column 27 is provided with multiple column parallel joints 25 and column diagonal braces 26 in the transverse direction of the bridge, and a channel steel connection system 30 is provided in the longitudinal direction of the bridge to enhance the overall stability. Subsequently, the top of the steel pipe column 27 is filled with concrete 22 for counterweight reinforcement, and a balance beam 20 is installed at the uppermost end. Then, the hanger 23 is installed. The bottom of the hanger 23 is connected to the main beam segment 1 by a pin 24, and a foot support 21 and a jack 19 are provided at the top through the balance beam 20. Finally, the jack 19 is used to tension and pre-tighten the hanger 23 to improve the bearing capacity and stability of the structure.

[0042] like Figure 7 As shown, before the secondary tensioning construction of the large cantilever prestressed cap beam is carried out, the upper support frame 39, ladder 31, vertical hanger 32, electric drive system 36, roller 37 and bottom platform frame 33 are assembled in the factory to form a self-propelled large cantilever cap beam tensioning basket. After the production is completed, it is transported to the site and installed at the construction position. The corresponding counterweight is performed on the upper support frame 39 and the steel plate is installed on the bottom platform frame 33. Then the operator enters the lower platform through the ladder 31 to perform the secondary tensioning operation. Finally, after the tensioning construction at the current position is completed, the roller 37 is driven by the electric drive system 36 to move the tensioning basket to the next construction position to continue the construction.

[0043] It should be noted that the parts in this embodiment that are the same or similar to those in the first embodiment can be referenced to each other and will not be described in detail in this application.

[0044] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

Claims

1. A construction method for a large cantilever prestressed cast-in-place cap beam, characterized in that: The construction steps include: S1. Construct the cap and pier, install high-strength pins, brackets and sand tops on the sides of the piers, and place the attached bracket on the sand top; S2. Splice the distribution beam and the patterned steel plate to form an integrated module, and hoist the integrated module above the attached bracket; S3. Install steel pipe columns on the cap, and set hangers between the top of the steel pipe columns and the main beam segments for tensioning and pre-tightening. S4. Assemble the self-propelled large cantilever cap beam tensioning hanging basket and install it to carry out secondary tensioning operation of large cantilever prestressed cap beams at different positions.

2. The construction method of the large cantilever prestressed cast-in-place cap beam according to claim 1 is characterized in that: In step S1, after the construction of the foundation is completed, the pier is constructed first, and a high-strength pin installation hole is reserved at the specified position of the pier. When the overall construction of the pier is completed, the high-strength pin, corbel and sand top components are installed, and then the attached bracket is assembled, and then the attached bracket is hoisted and installed, and the whole is placed on the sand top.

3. The construction method of the large cantilever prestressed cast-in-place cap beam according to claim 1 is characterized in that: The attached bracket includes a main beam segment, a cantilever beam segment, a steel diagonal brace, a longitudinal scissors brace and an internal support. The main beam segment and the cantilever beam segment are connected via a flange interface. A steel diagonal brace is provided at the bottom of the cantilever beam segment to connect with the main beam segment. The bottom of the steel diagonal brace is fixed to the flange interface on the main beam segment via a bottom plate. A top plate is arranged on the top of the steel diagonal brace and is welded and fixed to the cantilever beam segment. A longitudinal scissors brace is provided between the main beam segments, and an internal support is provided between the cantilever beam segments.

4. The construction method of the large cantilever prestressed cast-in-place cap beam according to claim 3 is characterized in that: In step S2, the distribution beam and the patterned steel plate on the bracket are divided into several modules and welded and fixed to form an integrated module. The integrated module is hoisted above the attached bracket, and then the distribution beam is connected and fixed to the main beam segment and cantilever beam segment below using U-bolts. Finally, a guardrail is fixed around the distribution beam.

5. The construction method of the large cantilever prestressed cast-in-place cap beam according to claim 1 is characterized in that: In step S3, firstly, the steel pipe columns are spliced ​​and fixedly installed on the pedestal. The steel pipe column segments are spliced ​​and installed by flanges and bolts. The steel pipe columns are provided with multiple column parallel joints and column diagonal braces in the transverse direction of the bridge, and a channel steel connection system is provided in the longitudinal direction of the bridge. In addition, filling concrete is provided on the top of the steel pipe column, and a balance beam is provided on the top of the steel pipe column. Then, the bottom of the hanger is fixedly connected with the main beam segment, and the top is fixedly installed with a jack and a foot support through the balance beam. Multiple groups of jacks simultaneously apply loads to tension and pre-tighten the hanger, so that the hanger generates prestress.

6. The construction method of the large cantilever prestressed cast-in-place cap beam according to claim 1 is characterized in that: In step S4, the self-propelled large cantilever cap beam tensioning basket includes an upper support frame, a ladder, a vertical hanger, an electric drive system, rollers and a bottom platform frame; the upper support frame is provided with four legs and four rollers, and the electric drive system is used to provide power to drive the rollers to move; the bottom platform frame is surrounded by a guard frame, and the guard frame is connected to the vertical hanger through a diagonal rod; the ladder is vertically arranged between the upper support frame and the bottom platform frame.

7. The construction method of the large cantilever prestressed cast-in-place cap beam according to claim 6 is characterized in that: In step S4, the upper support frame, ladder, vertical hanger, electric drive system, rollers and bottom platform frame are welded to form a self-propelled large cantilever cap beam tensioning basket, which is then installed on site to the designated position, and corresponding counterweights are placed on the upper support frame, and steel plates are installed on the bottom platform frame. The operator then enters the lower platform through the ladder to perform secondary tensioning operations. After the tensioning construction at the current position is completed, the rollers are driven by the electric drive system to move the tensioning basket to the next construction position.

8. Large cantilever prestressed cast-in-place cap beam, characterized in that: Obtained by the method according to any one of claims 1 to 7.

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