Bridge eccentric pier with vertical prestress

Abstract

The utility model discloses a bridge eccentric pier with vertical prestress, belongs to the field of bridge engineering, and solves the problems that a traditional eccentric pier is heavy in structure, large in investment and poor in visual effect. A plurality of prestressing tendons are jointly arranged in a pier column, a bearing platform and a pile foundation, and the prestressing tendons are located on the tension sides of the pier column, the bearing platform and the pile foundation; the lower end of the prestressing tendon is a prestressing anchoring end, a bottom pressure-bearing reinforcing mesh is arranged at the prestressing anchoring end, and the prestressing tendon is anchored in the pile foundation through the bottom pressure-bearing reinforcing mesh; the upper end of the prestressing tendon is a prestressing tension end, a top pressure-bearing reinforcing mesh is arranged at the prestressing tension end, and the prestressing tendon is fixedly embedded in the top of the pier column through the top pressure-bearing reinforcing mesh. By arranging the prestressing tendons, the vertical prestress of the pier is increased, the eccentric bending moment of the pier is balanced, and the stress distribution of the pier is improved, so that the stress requirements of a pier column and a pile foundation are met; the eccentric pier overcomes the defect that a traditional eccentric pier structure is cumbersome in appearance.

Description

TECHNICAL FIELD

[0001] The utility model belongs to bridge engineering field, concretely relates to a bridge eccentric pier of setting vertical prestress. BACKGROUND

[0002] With the rapid development of urban traffic, urban viaducts play a great role in relieving urban traffic pressure due to their advantages of less land occupation and less interference from surrounding traffic, and become an important part of modern transportation. The arrangement of the bridge pier of the urban viaduct not only needs to consider the demand of the viaduct itself, but also needs to take into account the clearance, passing clearance and overall landscape demand of the road under the bridge, and usually encounters the problem that the center line of the main beam of the viaduct does not coincide with the center line of the pier structure (i.e. transverse eccentric pier). Through investigation, the main reasons for the generation of the transverse eccentric pier of the urban viaduct include the following aspects.

[0003] 1) Topographic factor limitation. The city topography is complex and changeable, and when the viaduct crosses different terrains, the position of the pier column may need to be adjusted to adapt to the ground conditions, thereby causing the generation of eccentricity.

[0004] 2) Road alignment demand. In order to meet the smoothness of urban traffic and the demand of road alignment, the design of the viaduct often needs to be adjusted according to the direction and curvature of the road. This may cause the center line of the pier column to deviate from the center line of the bridge, forming an eccentric pier.

[0005] 3) The need of bridge structure form. The structure form of the viaduct is various, including continuous beam, simply supported beam, rigid frame bridge, etc. Different structure forms have different requirements for the arrangement and stress performance of the pier column, and sometimes in order to meet the overall stability and stress balance of the structure, an eccentric pier needs to be set.

[0006] 4) Construction error. In the process of bridge construction, due to improper control of construction precision or construction condition limitation, there may be deviation between the actual position of the pier column and the design position, thereby causing eccentricity.

[0007] Due to the design of the eccentric pier, the center of the pier column does not coincide with the center line of the bridge, so the pier column will bear eccentric load, so that the eccentric pier not only bears vertical pressure, but also bears bending moment due to eccentricity. The combined action of pressure and bending will cause complex stress distribution in the interior of the pier column, which puts higher requirements on the strength and stability of the pier column; and the pile foundation not only needs to bear the vertical pressure from the pier column, but also needs to bear the horizontal force and torque due to eccentric bending moment. This makes the stress state of the pile foundation complex and difficult to meet the stress requirement.

[0008] In order to cope with the eccentric pier bending-torsional coupling caused by these stress characteristics, in the past design, usually increase the pier structure size, increase the number of pile foundation to strengthen, resulting in eccentric pier compared to the same conditions under the non-eccentric pier, has the structure heavy, investment is larger, the visual effect is poor shortcoming. Practical new content

[0009] The utility model aims at providing a kind of bridge eccentric pier of setting vertical prestress, to solve the problem of traditional eccentric pier structure heavy, investment is larger, visual effect is poor.

[0010] The technical scheme of the utility model is: a kind of bridge eccentric pier of setting vertical prestress, including cover beam, pier column, pile cap and pile foundation connected in turn from top to bottom, the gravity center of pier column, pile cap and pile foundation does not coincide with the gravity center of bridge girder;It is characterized by: a plurality of beam prestress beams are jointly arranged in pier column, pile cap and pile foundation, and the prestress beam is located on the tension side of pier column, pile cap and pile foundation;The lower end of prestress beam is prestressed anchoring end, and bottom pressure reinforcement mesh is arranged at prestressed anchoring end, and bottom pressure reinforcement mesh anchors prestress beam in pile foundation;The upper end of prestress beam is prestressed tension end, and top pressure reinforcement mesh is arranged at prestressed tension end, and top pressure reinforcement mesh embeds prestress beam in the top of pier column.

[0011] As a further improvement of the utility model, the prestress beam uses steel strand, and a metal bellows pipe is sleeved around the steel strand, and the metal bellows pipe is filled with slurry.

[0012] As a further improvement of the utility model, the bottom pressure reinforcement mesh is welded with the reinforcement cage of pile foundation.

[0013] As a further improvement of the utility model, the top pressure reinforcement mesh is welded with the reinforcement framework of pier column.

[0014] The beneficial effects of the utility model are:

[0015] 1. Compared with the traditional eccentric pier, the utility model increases the vertical prestress of pier by setting prestress beam, balances eccentric pier bending moment, improves the stress distribution of pier, improves its bearing capacity and stability, to meet the stress requirements of pier column and pile foundation.

[0016] 2. The utility model overcomes the appearance of traditional eccentric pier structure heavy, improves the visual effect of pier light and comfortable, and reduces the number of pile foundation engineering, reduces the construction cost of engineering. DRAWINGS

[0017] Figure 1 It is the elevation structure schematic diagram of the utility model;

[0018] Figure 2The side surface structure schematic view of the utility model is shown in the figure.

[0019] Figure 3 The Figure 1 A-A view in the figure.

[0020] Figure 4 The Figure 1 B-B view in the figure.

[0021] Figure 5 The Figure 1 C-C view in the figure.

[0022] In the figure: 1, bent cap; 2, pier column; 3, pile cap; 4, pile foundation; 51, prestressed beam; 52, prestressed tension end; 53, prestressed anchoring end; 54, top bearing steel mesh; 55, bottom bearing steel mesh. DETAILED DESCRIPTION

[0023] The utility model will be described in detail below in combination with the drawings.

[0024] Example 1,

[0025] As Figures 1-5 shown, a bridge eccentric pier with vertical prestress is provided, which comprises a bent cap 1, a pier column 2, a pile cap 3 and a pile foundation 4 connected in sequence from top to bottom, the gravity centers of the pier column 2, the pile cap 3 and the pile foundation 4 do not coincide with the gravity center of the bridge girder; a plurality of beam prestress beams 51 are arranged in the pier column 2, the pile cap 3 and the pile foundation 4; the prestress beam 51 is located on the tension side of the pier column 2, the pile cap 3 and the pile foundation 4; the lower end of the prestress beam 51 is a prestressed anchoring end 53, a bottom bearing steel mesh 55 is arranged at the prestressed anchoring end 53, and the bottom bearing steel mesh 55 anchors the prestress beam 51 in the pile foundation 4; the upper end of the prestress beam 51 is a prestressed tension end 52, a top bearing steel mesh 54 is arranged at the prestressed tension end 52, and the top bearing steel mesh 54 embeds the prestress beam 51 at the top of the pier column 2.

[0026] The prestress beam 51 adopts a steel strand, a metal bellows is sleeved on the outer periphery of the steel strand, and slurry is poured into the metal bellows.

[0027] The bottom bearing steel mesh 55 is welded with the steel reinforcement cage of the pile foundation 4. The top bearing steel mesh 54 is welded with the steel reinforcement cage of the pier column 2.

[0028] The cap beam 1 is the direct structural member bearing the load from the superstructure, transferring the load to pier 2 and ensuring the stability and safety of the main beam. Cap beam 1 is 1.8m wide, 1.5m high, and has a cantilever length of 2.75m. The cantilevered side of cap beam 1 features a variable cross-section at the end, reducing its self-weight and enhancing its aesthetics. The other side is connected to the surface of pier 2 via a haunch, reducing torsional and distortional stresses at the connection point. Support pads and seismic blocks are installed on the top surface of cap beam 1.

[0029] Pier 2 is the main supporting component, supporting the cap beam 1 above and connecting to the pier cap 3 below. The cross-sectional dimensions of pier 2 are 2.0m (transverse direction) × 1.4m (longitudinal direction), with a radius of 20cm for the four corner rounded arcs. Pier 2 is poured in two stages. First, it is poured up to the tension section of the prestressed system 5. After the prestressing is completed, the remaining part is poured.

[0030] The foundation 3 is 3.0m thick and has a rectangular cross-section with each side measuring 3.4m. A plain concrete pad is poured below the bottom of foundation 3 to level the foundation pit, adjust the elevation, and distribute the bearing capacity of the foundation.

[0031] The pile cap 3 is connected to the pile foundation 4, which transfers the load to the deeper soil layer with good bearing capacity to meet the requirements of bearing capacity and settlement. In order to make the pile foundation 4 and the pile cap 3 more tightly connected and prevent leakage problems in the future, the pile foundation 4 should extend into the pile cap 3 by no less than 10cm.

[0032] The prestressed tendons 51 form a group anchorage system, totaling 5 tendons, divided into two rows. The inner row has 2 tendons, and the outer row has 3 tendons. The prestressed tendons 51 connect the pier column 2, the abutment 3, and the pile foundation 4 from top to bottom, and play a role in balancing the eccentric bending moment of the pier.

[0033] The prestressed strand 51 is made of 5-Φs15.2 high-strength, low-relaxation steel strand, with a control stress of 1395 MPa under the anchor. The steel strand is sheathed with a 55mm inner diameter corrugated metal tube. The prestressed anchoring end 53 is located in the pile foundation 4, with a burial depth of not less than 8m. A bottom-bearing steel mesh 55 is installed on the upper part of the prestressed anchoring end 53. The prestressed tensioning end 52 is located at the top of the pier column 2, and a top-bearing steel mesh 54 is installed at the lower part of the prestressed tensioning end 52.

[0034] The prestressed tendons 51, prestressed anchoring ends 53, and bottom bearing steel mesh 55 are positioned and installed during the binding of the reinforcement cage of the pile foundation 4, and are hoisted synchronously with the reinforcement cage. The bottom bearing steel mesh 55 is welded to the pile foundation reinforcement cage. The prestressed tensioning ends 52 and top bearing steel mesh 54 are installed synchronously during the binding of the reinforcement of the pier column 2. The top bearing steel mesh 54 is welded to the reinforcement skeleton of the pier column 2.

[0035] After the concrete of the first pour of pier column 2 is cured to a strength and elastic modulus of not less than 90% of the design value, the prestressed tendons 51 are tensioned. During tensioning, the tension force and elongation are controlled simultaneously, with the tension force as the main factor and the elongation as the verification factor.

[0036] After the prestressed tendon 51 is tensioned, its corrugated pipe is vacuum grouted. Before grouting, the debris inside the pipe is removed with pressurized water and dried with compressed air. The grouting should be dense. Grouting should be carried out within 24 hours after the prestressing is completed to prevent the steel strands from rusting.

Claims

1. A bridge eccentric pier with vertical prestressing, comprising a cap beam, a pier column, a pile cap, and pile foundations connected sequentially from top to bottom, wherein the center of gravity of the pier column, pile cap, and pile foundations does not coincide with the center of gravity of the main beam of the bridge; characterized in that: Multiple prestressed tendons (51) are installed in the pier (2), the cap (3) and the pile foundation (4). The prestressed tendons (51) are located on the tension side of the pier (2), the cap (3) and the pile foundation (4). The lower end of the prestressed tendon (51) is the prestressed anchoring end (53). The prestressed anchoring end (53) is provided with a bottom bearing steel mesh (55). The bottom bearing steel mesh (55) anchors the prestressed tendon (51) in the pile foundation (4). The upper end of the prestressed tendon (51) is the prestressing tensioning end (52). The prestressing tensioning end (52) is provided with a top bearing steel mesh (54). The top bearing steel mesh (54) embeds the prestressed tendon (51) in the top of the pier (2).

2. The eccentric pier for bridges with vertical prestressing as described in claim 1, characterized in that: The prestressed strand (51) is made of steel strand, and a metal corrugated pipe is sleeved around the steel strand, with grout injected inside the metal corrugated pipe.

3. The eccentric pier for bridges with vertical prestressing as described in claim 1, characterized in that: The bottom pressure-bearing steel mesh (55) is welded to the steel cage of the pile foundation (4).

4. A bridge eccentric pier with vertical prestressing as described in claim 1, characterized in that: The top pressure-bearing steel mesh (54) is welded to the steel skeleton of the pier column (2).

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