CN106320162A - Prefabricated assembly cap beam structure with steel shear keys and construction method - Google Patents

Abstract

The invention relates to a prefabricated assembled cover beam structure and construction method using steel shear keys. The steel shear keys of the prefabricated assembled cover beam adopt male-female paired shear keys, and the material is cast from ductile iron or high-quality carbon structural steel. become. Divide the cover beam into three prefabricated components, pre-embed the female shear key at the joint of the two external hanging sections, and pre-embed the male shear key at the joint of the middle section; use a crane to hoist the middle section and the two outer section components separately, After the position is calibrated, the first-stage prestressed tendons are threaded and stretched to connect the three sections of the structure into a whole, and the prestressed channel is closed and anchored by grouting; High-pressure grouting to deal with the joint between the male and female shear keys. Compared with the prior art, the present invention reduces the complexity of traditional large and small shear keys in the prefabrication stage; This method not only facilitates the determination of the position during the hoisting process, but also more effectively promotes the engagement between components.

Description

Prefabricated assembled cover beam structure and construction method using steel shear key

technical field

The invention relates to a prefabricated cover beam structure, in particular to a prefabricated cover beam structure and a construction method using steel shear keys.

Background technique

The cast-in-place construction of concrete bridges requires a large number of formwork and support systems. Under unfavorable construction conditions, it is not feasible to erect a full-height bracket. The construction of the cover beam belongs to high-altitude operations, and a large amount of concrete is poured on site, so the construction risk is high. The method of prefabricated and assembled cover beams can speed up the construction speed and ensure the quality, and at the same time, it is very economical considering the scale effect.

At this stage, the shear design of prefabricated bridge assembly mainly adopts toothed shear keys, which are specifically divided into large shear keys and small shear keys. The disadvantage is that the prefabricated formwork needs to be shaped with concave-convex edges and corners, the construction is complicated, and the degree of occlusal matching is not high. Therefore, there is a need for a new male-female paired steel shear key. Melted and forged steel is easy to form, the precision of the components can reach millimeters, and the matching degree is high. The pre-embedded treatment does not require special and careful treatment of the formwork, which can avoid the above problems.

Contents of the invention

The invention proposes a prefabricated assembled cover beam structure and a construction method using steel shear keys. The structure adopts a new male-female paired steel shear key and is applied to the prefabricated assembled construction of the cover beam. This structure not only facilitates assembly and positioning, but also improves the shear resistance of the spliced surface.

In order to achieve the above object, the technical solution of the present invention is: a prefabricated assembled cover beam structure using steel shear keys, including steel shear keys, concrete components of the prefabricated cover beam, and the concrete components of the prefabricated cover beam are pre-embedded The steel shear key is connected, and each steel shear key is composed of a male shear key and a female shear key in pairs; the male shear key and the female shear key are provided with crescent patterns on the contact surface with the concrete, It is used to generate mechanical bite force between the concrete components of the prefabricated cover beam; the tail end of the female shear key is provided with a grouting hole, and the grouting hole is connected to the outside of the concrete component of the prefabricated cover beam through a PVC pipe, which is convenient Grouting seals the joints between male and female shear keys.

The steel shear key is cast from ductile iron or high-quality carbon structural steel.

A construction method for prefabricated assembled cap beams using steel shear keys, the specific steps are:

Step 1: Template making of prefabricated cover beams

Divide the prefabricated cover beam into three sections of concrete components A, B, and C, and erect prefabricated formwork respectively;

Step 2, pre-embedded steel shear key and pouring concrete

Pre-embed the female type shear key at the joint of the prefabricated formwork of the two external concrete components A and C 2. Embed the male type shear key at the joint of the prefabricated formwork of the concrete component B in the middle section, and use a level to check the horizontal position Calibrate, make the male shear key and the female shear key match and match, and then fix the position with the steel bar to prevent misalignment during concrete pouring; then pour concrete, start from the steel shear key when pouring concrete, and pour in sections , to ensure the quality of prefabricated cap beam components;

Step 3, hoisting the concrete components of the prefabricated cap beam

1) Hoisting concrete component B: The concrete component B in the middle section is hoisted by the crane, according to the predetermined assembly plan of the pier 7 and the middle section, slowly placed until it is in full contact with the pier 7, the crane is withdrawn, and cement grout is injected at the assembly interface to seal it;

2) Hoisting concrete components A and C: The crane hoists concrete components A and C at the same time, and paints epoxy resin at the interface of the three sections of components. Taking the male and female steel shear keys as calibration points, the female shear key and the The male type shear key is docked and inserted, and after the docking is completed, stop the lifting work of the crane;

Step 4: Stretch the first stage prestressed tendons

Put the pre-prepared prestressed tendons along the hole in the concrete member, use the post-tensioning method to stretch the steel bars at both ends, stretch the prestressed tendons in the first stage and anchor them, so that the concrete members A and C are closely attached to the concrete member B , and then remove the crane, and close the prestressed tunnel in the first stage by grouting;

Step 5, shear key joint treatment Use a small leather tube to connect the grouting machine to the PVC pipe, fix the interface with clamps to prevent the leather tube from detaching from the pipe under high pressure, start the grouting machine to inject epoxy into the pipe under high pressure until the grout oozes out along the joints between concrete component A and concrete component B, concrete component A and concrete component C, close the grouting machine, remove the small leather tube, and wipe and clean the oozing resin solution;

Step 6, stretching the second-stage prestressed tendons

Blocks are placed on concrete members A and C, box girder support pads are placed on concrete members A, B and C, and then prestressed tendons are stretched in the second stage, and the prestressed hole is finally closed by grouting, anchoring and joint Seams complete the entire assembly process.

The beneficial effects of the invention are: the prefabricated assembled cover beam adopts a new type of male-female paired steel shear key, which is the first in terms of the shear resistance structure of the prefabricated assembled cover beam. The difference from the tooth-type large and small shear keys used in general prefabricated assembled bridges is that the shear keys in the present invention need to be pre-embedded, which reduces the complexity of the traditional large and small shear keys in the prefabrication stage; The method of male-female pairing not only facilitates the determination of the position during the hoisting process, but also more effectively promotes the engagement between components.

The present invention has the following advantages in practical engineering applications: steel shear key structure casting is easy to form, high dimensional accuracy, and high matching degree for hoisting and splicing; in the case of reasonable structural design, ductile cast iron or high-quality carbon structural steel can be used for casting. The shear key is directly embedded in the assembled component, which has low requirements for the detailed production of the formwork, and saves formwork materials and a large amount of human resources in mass production; the prestressed tendon tension and anchorage method shortens the cost of traditional cast-in-place cover beams. It requires working time. In the whole, large, and medium-to-long-term overpass bridge projects, the total construction period of the project is greatly shortened, and the timeliness performance is improved; the shear key of the male and female pairs not only plays the role of a temporary fulcrum, but also has the key teeth occluded The function greatly improves the shear reliability of the splicing surface.

Description of drawings

Figure 1 is a schematic diagram of the structure of a male-female paired steel shear key;

Fig. 2 is the top view of Fig. 1;

Fig. 3 is a schematic diagram of the overall structure of the prefabricated assembled cover beam;

Figure 4 is a partially enlarged schematic diagram of the circled point in Figure 3;

Fig. 5 is the top view of the interface of concrete members A and B;

Fig. 6 is the schematic diagram of interface of concrete member A;

Fig. 7 is a flowchart of the construction method of the prefabricated assembled cap beam using steel shear keys according to the present invention.

detailed description

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

As shown in Figures 1 to 6, the prefabricated assembled cover beam structure using steel shear keys of the present invention includes concrete components of the prefabricated cover beam, steel shear keys, grouting holes 4, PVC pipes 5, and the like. The concrete components of the prefabricated cover beams are connected by pre-embedded steel shear keys. A single steel shear key is divided into a male shear key 1 and a female shear key 2. The boss on the male shear key 1 is connected to the The grooves on the female shear key 2 are paired and connected, and the steel shear key is cast from ductile iron or high-quality carbon structural steel; the male shear key 1 and the female shear key 2 are on the contact surface with the concrete There are crescent patterns 3, the purpose of which is to generate mechanical engagement with concrete components A, B, and C; there is a grouting hole 4 at the end of the female shear key 2, and the grouting hole 4 is connected to the concrete component through a PVC pipe 5 The outer side of A and C is convenient for grouting to close the joint 6 between the male and female shear keys.

As shown in Figure 7, the construction method of the prefabricated assembled cover beam that adopts steel shear key of the present invention, take the prefabricated cover beam of 31m of longitudinal total length as example, the prefabricated cover beam among the present invention is made of concrete members A, B, C three Section components (Figure 3), the construction steps and requirements are as follows:

a. Divide the prefabricated cover beam into three sections of concrete components A, B, and C. The three sections are respectively erected for precast formwork. The concrete components A and C are two external hanging sections. The female shear key 2 is pre-embedded at the joint, and the concrete component B is In the middle section, the male shear key 1 is pre-embedded at the joint, and the pre-embedded position is only in the compression area of the component; when the steel shear key is pre-embedded, it is necessary to use a level to calibrate the horizontal position, and the end of the female shear key 2 Note The grout hole 4 is connected to the PVC pipe 5, and steel bars are used to fix the position of the steel shear key and the PVC pipe to prevent misalignment during concrete pouring; when pouring, start from the steel shear key and pour in sections to ensure that the prefabricated cover beam components Quality: During the prefabrication process, there are three layers of symmetrical prestressing tendon channels S shown in Figure 6, and plastic corrugated tubes are used for the prestressing tendon sleeves.

b. After the components are transported to the assembly construction site, use a crane to hoist the concrete component B in the middle section first, and apply epoxy resin on the interface with the pier as a bonding layer. After identifying the assembly position, slowly place it until it is completely assembled with the pier 7, Withdraw the lifting device and inject cement slurry at the interface to seal it.

c. Use a crane to hoist concrete components A and C at the same time, paint epoxy resin at the interface of the three sections, take the male and female shear keys 1 and 2 as calibration points, and align the female shear key 2 with the male shear key The shear key 1 is docked and inserted, and after the docking is completed, stop the lifting work of the crane;

d. Prestressed steel strands are inserted along the holes of the three-layer symmetrical prestressed tendon channel S. The specifications of the steel strands are uniformly 15-фs15.20 steel strands. Both ends are stretched by post-tensioning, and the first stage of tension is prestressed. The anchor plate must be perpendicular to the center line of the steel beam, the two ends should be tensioned symmetrically, the tensile stress and elongation should be controlled in both directions, the anchorage should be fixed so that the concrete members A, C and the concrete member B are closely attached, and the lifting device should be removed. The prestressed channel of the first stage is closed by grouting, and the strength of the grout is C45;

e. Use a rubber tube to connect the small grouting machine to the PVC pipe 5, and fix the interface with a fixture to prevent the leather tube from detaching from the pipe 5 under high pressure. Start the grouting machine and inject epoxy resin into the pipe 5 under high pressure until the slurry Seep along the joints of concrete components A, B, concrete components A, C, close the grouting machine, remove the small leather tube, and wipe and clean the oozing resin solution;

f. Place the stopper 8 and the anti-seismic rubber bearing 9 as shown in Figure 3. After the assembly of the stopper 8 is completed, the installation of the anti-seismic rubber bearing needs to be installed symmetrically from the center of the structure to both sides, and then the second stage of pre-tensioning is carried out. Stress tendons, that is, the uppermost prestressed tendons shown in Figure 6, the anchor plate must be perpendicular to the center line of the steel bundle, the two ends of the tension should be symmetrical, the tensile stress and elongation can be controlled in both directions, and the anchorage should be fixed after the prestress reaches the design requirements , Remove the lifting device, grout in the tunnel, the grout strength is C45, and the surface joints are sealed and anchored with epoxy resin.

Claims (3)

1. A prefabricated assembled cover beam structure adopting steel shear keys, comprising steel shear keys, concrete components of prefabricated cover beams, connected by pre-embedded steel shear keys between the concrete components of prefabricated cover beams, characterized in that : Each steel shear key is composed of a male shear key (1) and a female shear key (2) in pairs; the male shear key (1) and female shear key (2) are in contact with the concrete There is a crescent pattern (3) on it, which is used to generate mechanical engagement force with the concrete components of the prefabricated cover beam; the tail end of the female shear key (2) is provided with a grouting hole (4), and the grouting hole (4) The concrete member connected to the prefabricated cover beam through the PVC pipe (5) has an outer side, which is convenient for grouting to close the joint (6) between the male and female shear keys. 2. The prefabricated assembled cover beam structure using steel shear keys according to claim 1, characterized in that: the steel shear keys are cast from ductile iron or high-quality carbon structural steel. 3. A construction method for a prefabricated assembled cap beam adopting steel shear keys, characterized in that the specific steps are: Step 1: Template making of prefabricated cover beams Divide the prefabricated cover beam into three sections of concrete components A, B, and C, and erect prefabricated formwork respectively; Step 2, pre-embedded steel shear key and pouring concrete Pre-embed the female shear key (2) at the joint of the prefabricated formwork of the two external concrete components A and C, and pre-embed the male-shaped steel shear key (1) at the joint of the prefabricated formwork of the concrete component B in the middle section, Calibrate the position in the horizontal direction with a spirit level so that the male shear key (1) and the female shear key (2) are paired and coincident, and then fix the position with steel bars to prevent misalignment during concrete pouring; then concrete is poured, and when concrete is poured Starting from the steel shear key, match the pouring in sections to ensure the quality of the prefabricated cap beam components; Step 3, hoisting the concrete components of the prefabricated cap beam 1) Hoisting concrete component B: hoist the concrete component B in the middle section by the crane, place it slowly until it is in full contact with the pier (7) according to the predetermined assembly plan of the pier (7) and the middle section, withdraw the crane, and inject cement slurry at the assembly interface closed; 2) Hoisting concrete components A and C: The crane hoists concrete components A and C at the same time, and paints epoxy resin at the interface of the three sections of components. With the male and female shear keys 1 and 2 as calibration points, the female shear bond The force key (2) is docked and inserted with the male type shear key (1), and after the docking is completed, stop the lifting work of the crane; Step 4: Stretch the first stage prestressed tendons Put the pre-prepared prestressed tendons along the hole in the concrete member, use the post-tensioning method to stretch the steel bars at both ends, stretch the prestressed tendons in the first stage and anchor them, so that the concrete members A and C are closely attached to the concrete member B , and then remove the crane, and close the prestressed tunnel in the first stage by grouting; Step 5, shear key joint treatment Use a small leather tube to connect the grouting machine to the PVC pipe (5), fix the interface with clamps to prevent the leather tube from detaching from the pipe (5) under high pressure, start the grouting machine to inject epoxy into the pipe (5) under high pressure until the grout oozes out along the joints between concrete component A and concrete component B, concrete component A and concrete component C, close the grouting machine, remove the small leather tube, and wipe and clean the oozing resin solution; Step 6, stretching the second-stage prestressed tendons Place stoppers (8) on concrete members A and C, place box girder support pads (9) on concrete members A, B and C, then stretch the prestressed tendons in the second stage, and finally complete the prestressed hole grouting Close, anchor and seam to complete the entire assembly process.