Construction method of large-span super-long prestressed steel box concrete cover beam

Abstract

The invention discloses a construction method of a large-span super-long prestressed steel box concrete cover beam. The construction method comprises the specific operation steps of steel box machining, segmented transportation, support erecting, steel box cover beam segmented hoisting, cover beam segmented steel box welding, steel strand pulling, steel pipe pulling, prestress applying, cover beam and pier column welding connection, self-compacting concrete pouring in a steel box, concrete compactness checking in the box, prestress releasing and tensioning, coping and cleaning. The construction method comprises the specific operation steps of steel box machining, segmented transportation, support erecting, steel box cover beam segmented hoisting, cover beam segmented steel box welding, steel strand pulling, steel pipe pulling, prestress applying, cover beam and pier column welding connection, the method mainly solves the problems that a novel structure of a large-span super-long prestressed steel box concrete cover beam does not have a matched construction method, super-high and super-long steel boxes cannot be integrally transported due to height and length limitation and cannot be transported in a segmented mode, steel strand pulling cannot be conducted in advance during installation, and meanwhile prestressed tensioning of the steel boxes is difficult. According to the method, transportation, hoisting, steel strand pulling, tensioning, concrete pouring and the like of the cover beam steel box are designed, and a safe, economical and effective construction method is provided for the large-span super-long prestressed steel box concrete cover beam.

Description

Technical Field

[0001] The invention relates to the field of large-span and ultra-long prestressed steel box concrete cap beam construction, and in particular to a large-span and ultra-long prestressed steel box concrete cap beam construction method. Background Art

[0002] With the construction of highway bridges, route design has gradually developed towards more lanes, wider bridge decks, and stronger load-bearing capacity. Under special environmental conditions such as crossing lines, crossing rivers, and high environmental protection requirements, bridges ensure the width of the bridge deck by increasing the lateral spacing between piers. Large-span and ultra-long prestressed steel box concrete cap beams are introduced. There is no specific matching construction method for this structure. Similar prestressed steel box concrete cap beam structures of ramp bridges are still used for the construction of large-span and ultra-long structures. There are still many problems: (1) The ultra-long cap beam steel box structure has strict requirements on transportation vehicles and routes, and cannot be transported as a whole; (2) The large-span structure makes its structure height too high, and the overall vertical transportation height exceeds the limit. Horizontal transportation is opposite to the main force direction of the structure, and the self-weight produces large lateral deformation; (3) The overall installation of ultra-long and ultra-heavy structures requires large lifting equipment, which is economical and has high safety risks; (4) The overall assembly and welding of ultra-long structures at the bottom of the pier takes a long time, occupies a large space, and there is no large lifting equipment movement channel. Cross-operation is impossible, and strict requirements are placed on the working surface; (5) The steel strands cannot be bundled in advance during the processing of the cap beam steel box due to segmented transportation. Summary of the invention

[0003] Therefore, in order to solve the above-mentioned deficiencies, the present invention provides a method for constructing a large-span and extra-long prestressed steel box concrete cap beam. This method mainly solves the problem that there is no matching construction method for the new structure of large-span and extra-long prestressed steel box concrete cap beam. The extra-high and extra-long steel boxes cannot be transported as a whole due to height and length restrictions. The segmented transportation and installation cannot be performed in advance to thread the steel strands. At the same time, the prestressing of the steel box is difficult. This method designs the transportation and hoisting of the steel box cap beam, the threading and tensioning of the steel strands, and the pouring of concrete, providing a safe, economical and effective construction method for large-span and extra-long prestressed steel box concrete cap beams.

[0004] The present invention is implemented by constructing a large-span ultra-long prestressed steel box concrete cap beam construction method, which is characterized by the following specific operation steps: Step 1, steel box processing: The cap beam steel box is processed in sections in the steel plant. The section positions are determined according to the center of gravity and the pier column structure positions. Steel guide plates with holes are set at a certain interval in the section steel box, and steel pipes are inserted into the holes to assist on-site beam threading; Step 2, segmented transportation: The cap beam steel box is transported to the construction site in segments. The low-side steel box segments are transported vertically, while the high-side steel box segments are transported horizontally due to the height limit of transportation. Temporary support and fixing devices are set during transportation. Step 3, support erection: Before installing the steel structure, pre-erect the assembled support platform at the large-span and extra-long cap beam sections; Step 4, hoisting of steel box cap beam in sections: mark the central axis of the pier top, and control marks in the transverse and longitudinal directions of the bridge before installation; after hoisting in place, observe the two axes and ensure that the axes coincide, and smoothly insert the positioning plate at the bottom of the cap beam into the pier column; lay out the central axis of the cap beam, adjust the longitudinal and transverse positions of the cap beam, and check the elevation of the top of the cap beam; use the jack and hand winch on the bracket to adjust the height and plane position of the cap beam section, and after adjustment in place, immediately use the code plate to fix the sectioned steel box; Step 5, welding of the cap beam segmented steel box: after uniform base welding, the web is welded symmetrically, the bottom plate and the top plate are welded crosswise, and the welding is staggered with the web; 24 hours after welding, the weld is tested by non-destructive testing; Step 6, strand bundle: install the steel cap beam tensioning platform, set the hand hole at the web of the cap beam, adjust the steel pipe docking interface in the box, and thread the steel strands in the reserved steel pipe of the cap beam steel box. Reserve 90cm tensioning length for the strands outside the head plates at both ends; Step 7, steel pipe removal: After the bundle is inserted, the steel pipe is removed, cut into a certain length, and reused; Step 8, apply prestress: install prestressed tensioning plates, and use symmetrical and graded loading at both ends for prestressing. The loading mode is 0%→30%→60%→100% to control the tensioning stress. During the tensioning process, the deformation of the structural section, the cantilever end of the cap beam, the mid-span, the top of the column and other positions are controlled. The total station measures the horizontal and vertical deformations and the lateral displacement of the pier column at graded fixed points. When the vertical or horizontal deformation of the prestressed steel strand exceeds 30mm, the loading should be stopped immediately, and the cause should be found and the hidden danger should be eliminated before tensioning. Step 9, welding connection between cap beam and pier column: installing the pier column cap beam welding operation platform, welding the weld between pier column and cap beam; Step 10, pouring self-compacting concrete in the steel box: using a pumping + hopper method to pour concrete in the box; Step 11: 4 days after the pouring is completed, use a special hammer to knock and check the density of the concrete in the box, define the knocking inspection area and use ultrasonic method to detect; Step 12, prestressing release: when the concrete strength reaches more than 80% of the design strength grade, release the steel strands and remove the tension anchor plates; Step 13, grinding and cleaning: Grind the steel strands to be flush with the end face of the cap beam, chisel out and clean the concrete overflowing from the end face as well as the garbage and dirt on the surface, and seal the sealing plate.

[0005] The present invention has the following advantages: (1) The method uses segmented transportation and lifting to solve the problem of over-length and over-height of the steel box cap beam, while reducing the overall lifting weight, reducing safety risks and improving economy; (2) The method uses steel pipes as the strand threading channel to solve the problem of difficulty in threading the steel strands in the segmented steel box cap beam, while avoiding damage to the steel strands caused by high temperature of the segmented steel box welding; (3) The assembly bracket, tensioning platform and pier column-cap beam fully automatic upper and lower platforms of the method all adopt prefabricated structures, which can be transported and reused as a whole, which is safe and reliable; (4) The method uses pier top docking tensioning to avoid two times of transportation, avoid occupying the space under the bridge, and allow the lifting machinery to pass smoothly, reducing the difficulty of construction organization; (5) This patent provides a safe, economical and reliable construction method for large-span and ultra-long prestressed steel box concrete cap beams, which has reference significance for the construction of similar structures. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 It is a flow chart of the construction method of large-span and ultra-long prestressed steel box concrete cap beam; Figure 2 This is a schematic diagram of the segmented hoisting of a large-span, ultra-long prestressed steel box concrete cap beam; Figure 3 This is a schematic diagram of the construction of large-span and ultra-long prestressed steel box concrete cap beam. DETAILED DESCRIPTION

[0007] The following will be combined with the attached Figure 1-Figure 3 The present invention is described in detail, and the technical solutions in the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0008] The present invention provides a method for constructing a large-span ultra-long prestressed steel box concrete cap beam, and the specific operation steps are as follows: Step 1: Steel box processing. The cap beam steel box is processed in sections in the steel plant. The section positions are determined according to the center of gravity and the pier column structure position. Perforated guide steel plates are set at a certain interval in the section steel box, and steel pipes are inserted into the holes to assist on-site guide.

[0009] Step 2: Segmented transportation. The cap beam steel box is transported to the construction site in segments. The low-side steel box segments are transported vertically, while the high-side steel box segments are transported horizontally due to height restrictions. Temporary supports and fixing devices are set up during transportation.

[0010] Step 3: Scaffolding installation. Before installing the steel structure, a prefabricated assembly scaffolding platform is pre-installed at the large-span and extra-long cap beam sections.

[0011] Step 4: Lift the steel box cap beam in sections. Before installation, mark the center axis of the pier top, and control marks in the transverse and longitudinal directions; after lifting in place, observe the two axes and ensure that they coincide, and smoothly insert the positioning plate at the bottom of the cap beam into the pier column; lay out the center axis of the cap beam, adjust the longitudinal and transverse positions of the cap beam, and check the top elevation of the cap beam; use the jack on the bracket and the hand winch to adjust the height and plane position of the cap beam sections. After adjustment, immediately use the stacking plate to fix the sectioned steel box.

[0012] Step 5: Welding of the cap beam segmented steel box. After uniform base welding, the web is welded symmetrically, the bottom plate and top plate are welded crosswise, and the web is welded staggered; 24 hours after welding, the weld is tested by non-destructive testing.

[0013] Step 6: Stranding of steel strands. Install the steel cap beam tensioning platform, set hand holes at the web of the cap beam, adjust the docking interface of the steel pipe in the box, and thread the steel strands through the reserved steel pipes in the cap beam steel box. Reserve a 90cm tensioning length for the steel strands beyond the end plates at both ends.

[0014] Step 7: Steel pipe removal. After the bundle is inserted, the steel pipe is removed and cut into certain lengths for reuse; Step 8: Apply prestress. Install the prestressing plate. The prestressing adopts symmetrical and graded loading at both ends. The loading mode is 0%→30%→60%→100% to control the prestressing stress. During the prestressing process, the deformation of the structural section, the cantilever end of the cap beam, the mid-span, the top of the column and other positions is controlled. The total station measures the horizontal and vertical deformations and the lateral displacement of the pier column at graded fixed points. When the prestressing steel strand is found to have a vertical or horizontal deformation of more than 30mm, the loading should be stopped immediately, and the cause should be found and the hidden danger should be eliminated before prestressing.

[0015] Step 9: Welding connection between cap beam and pier column. Install the pier column cap beam welding operation platform and weld the weld between pier column and cap beam.

[0016] Step 10: Pour the self-compacting concrete in the steel box. Use the pumping + hopper method to pour the concrete in the box.

[0017] Step 11: 4 days after pouring, use a special hammer to knock and check the density of the concrete in the box, mark the area for knocking and checking the voids, and use ultrasonic testing in conjunction.

[0018] Step 12: Prestressing release: When the concrete strength reaches 80% or more of the design strength grade, release the steel strands and remove the tension anchor plates.

[0019] Step 13: Grind and clean. Grind the steel strands to be flush with the end face of the cap beam, chisel off and clean the concrete overflowing from the end face as well as the garbage and dirt on the surface, and seal the sealing plate.

[0020] This patent has the following advantages and beneficial effects: (1) This method uses segmented transportation and lifting to solve the problem of the over-length and over-height of the cap beam steel box. At the same time, it reduces the overall lifting weight, reduces safety risks, and improves economic efficiency.

[0021] (2) This method uses a steel pipe as a channel for the strands to pass through, which solves the problem of difficulty in passing the strands through the segmented cap beam steel box. At the same time, it avoids damage to the strands caused by high temperature during welding of the segmented steel box.

[0022] (3) In this method, the assembled bracket, tensioning platform, and pier-cap beam fully automatic upper and lower platforms all adopt prefabricated structures, which can be transported and reused as a whole, which is safe and reliable.

[0023] (4) This method uses pier top docking and tensioning, which avoids two transfers and avoids occupying the space under the bridge. The lifting machinery can pass smoothly, reducing the difficulty of construction organization.

[0024] (5) This patent provides a safe, economical and reliable construction method for large-span and ultra-long prestressed steel box concrete cap beams, which has reference significance for the construction of similar structures.

[0025] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for constructing a large-span ultra-long prestressed steel box concrete cap beam, characterized in that: The specific steps are: Step 1, steel box processing: The cap beam steel box is processed in sections in the steel plant. The section positions are determined according to the center of gravity and the pier column structure positions. Steel guide plates with holes are set at a certain interval in the section steel box, and steel pipes are inserted into the holes to assist on-site beam threading; Step 2, segmented transportation: The cap beam steel box is transported to the construction site in segments. The low-side steel box segments are transported vertically, while the high-side steel box segments are transported horizontally due to the height limit of transportation. Temporary support and fixing devices are set during transportation. Step 3, support erection: Before installing the steel structure, pre-erect the assembled support platform at the large-span and extra-long cap beam sections; Step 4, hoisting of steel box cap beam in sections: mark the central axis of the pier top, and control marks in the transverse and longitudinal directions of the bridge before installation; after hoisting in place, observe the two axes and ensure that the axes coincide, and smoothly insert the positioning plate at the bottom of the cap beam into the pier column; lay out the central axis of the cap beam, adjust the longitudinal and transverse positions of the cap beam, and check the elevation of the top of the cap beam; use the jack and hand winch on the bracket to adjust the height and plane position of the cap beam section, and after adjustment in place, immediately use the code plate to fix the sectioned steel box; Step 5, welding of the cap beam segmented steel box: after uniform base welding, the web is welded symmetrically, the bottom plate and the top plate are welded crosswise, and the welding is staggered with the web; 24 hours after welding, the weld is tested by non-destructive testing; Step 6, strand bundle: install the steel cap beam tensioning platform, set the hand hole at the web of the cap beam, adjust the steel pipe docking interface in the box, and thread the steel strands in the reserved steel pipe of the cap beam steel box. Reserve 90cm tensioning length for the strands outside the head plates at both ends; Step 7, steel pipe removal: After the bundle is inserted, the steel pipe is removed, cut into a certain length, and reused; Step 8, apply prestress: install prestressed tensioning plates, and use symmetrical and graded loading at both ends for prestressing. The loading mode is 0%→30%→60%→100% to control the tensioning stress. During the tensioning process, the deformation of the structural section, the cantilever end of the cap beam, the mid-span, the top of the column and other positions are controlled. The total station measures the horizontal and vertical deformations and the lateral displacement of the pier column at graded fixed points. When the vertical or horizontal deformation of the prestressed steel strand exceeds 30mm, the loading should be stopped immediately, and the cause should be found and the hidden danger should be eliminated before tensioning. Step 9, welding connection between cap beam and pier column: installing the pier column cap beam welding operation platform, welding the weld between pier column and cap beam; Step 10, pouring self-compacting concrete in the steel box: using a pumping + hopper method to pour concrete in the box; Step 11: 4 days after the pouring is completed, use a special hammer to knock and check the density of the concrete in the box, define the knocking inspection area and use ultrasonic method to detect; Step 12, prestressing release: when the concrete strength reaches more than 80% of the design strength grade, release the steel strands and remove the tension anchor plates; Step 13, grinding and cleaning: Grind the steel strands to be flush with the end face of the cap beam, chisel out and clean the concrete overflowing from the end face as well as the garbage and dirt on the surface, and seal the sealing plate.

Images