CN102587296A - Self-balancing external prestressing strengthening method for bridge structure - Google Patents

Abstract

The invention relates to a self-balancing external prestressing strengthening method for a bridge structure. The self-balancing external prestressing strengthening method is characterized by comprising the following steps of: carrying out interface processing at a connecting place (5) of a top flange of a concrete beam; (2) inserting reinforced bars at the connecting place (5) of the top flange of the concrete beam; (3) installing the reinforced bars at the connecting place (5) of the top flange of the concrete beam; (4) installing the reinforced bar of a steering block (6) and a diverter (9) at the bottom of the beam; (5) symmetrically adding diaphragm plates at a place far away from the end of the beam by 2-3m, and installing an anchorage device (10); (6) concreting the connecting place (5) of the top flange of the beam, the steering block (6) and the newly added diaphragm plates (8); and (7) installing and tensioning an anchoring external cable, thus obtaining a self-balancing external prestressing strengthening structure. An external prestressing system can be used for detecting and adjusting the stress of the cable at any time, inspecting the corrosion condition of the cable and can also be used for maintaining and replacing the cable when necessary. The self-compacting concrete solves the problems of dense reinforcement assembly, complex structure, narrow space of formworks and traditional structural members, cavities caused by the blocking of aggregates and the like, effectively ensures the dense degree of placing concrete and increases the strengthening effect. The self-balancing external prestressing strengthening method can be used for strengthening heavy railroad brides, concrete box girders and T beams.

Description

A self-balancing external prestressed reinforcement method for bridge structures

technical field

The invention relates to the field of bridge and structural engineering in civil engineering, in particular to a method for reinforcing and strengthening a bridge superstructure and a construction process, in particular to the rapid strengthening and upgrading of heavy-duty railway bridges.

Background technique

With the continuous deepening of large-scale construction of high-speed and passenger-dedicated railways, my country's railway high-speed and rapid passenger transport network has gradually formed. model. Therefore, the heavy-duty reconstruction and evaluation of existing railway bridges is one of the urgent problems to be solved in my country's railways.

Heavy-duty railways have large transportation capacity and significant economic and social benefits. The development of heavy-duty railway transportation has become the development direction of railway transportation in all countries in the world, and it is also the main way for my country to accelerate the improvement of railway transportation capacity. Accelerating the construction of coal transportation channels and the expansion and transformation of existing lines to form a coal transportation system with strong transportation capacity, advanced organization and perfect functions is one of the important development contents of my country's "medium and long-term railway network planning". To ensure the efficient and safe operation of heavy-haul railways, all elements that make up the heavy-haul railway system must maintain high standards. Coupled with my country's unique high traffic density, this puts forward higher requirements for my country's heavy-haul railway technology.

Railway heavy-haul transportation is a comprehensive system engineering, involving the whole process of railway design, construction, operation and maintenance. The main difference between heavy-duty railways and ordinary railways is that the dynamic load strength and frequency of bridges and subgrades are increased, which causes increased load effects and material stress amplitudes, resulting in the use of existing railway bridges, subgrades and tracks. The lifespan is shortened, the safety reserves of the structure's strength, stiffness, stability, etc. are reduced, and the probability of various diseases is increased, and the hazards are intensified. For example, after several years of heavy-duty operation in my country's Daqin Line and Shuohuang Line, bridge diaphragm fractures, beam body cracks, piers and abutment cracks, beam end jacking, support tilting, culvert cracks, culvert deformation and Subgrade subsidence in bridge-culvert transition section, subsidence of interval embankment and cutting section, insufficient road shoulder width, subgrade mud and mud discharge, ballast bed compaction, poor drainage and other types of diseases. With the increase of the axle load of my country's heavy-duty railway transportation, the continuous improvement of traction quality and the continuous increase of traffic density, the service conditions of existing railway bridges and roadbeds will deteriorate, and the probability of bridge and roadbed diseases will further increase.

With the continuous increase of traffic volume, various diseases of the bridge are becoming more and more prominent, and the service performance is continuously declining, especially the prestressed concrete segmented beam with a span of 32.0m is weakened due to the weak transverse connection, and the fracture of the diaphragm is increasing year by year. When the train passed, some bridges even had catenary falling off the bow due to too much swing. In order to ensure the safety of transportation, ensure the normal use of equipment, and meet the needs of increasing traffic volume, the bridge must be reinforced. How to effectively take reinforcement measures to improve the stiffness, strength and fatigue durability of such beams has become a matter of great concern to the railway transportation management department.

At present, the commonly used reinforcement methods in bridge engineering include enlarging section reinforcement method, bonded steel reinforcement method, FRP material paste reinforcement method, changing structural force transmission method and outsourcing steel reinforcement method, etc. Affected by structural form or material properties, these traditional reinforcement methods have certain limitations.

(1) When adopting the reinforcement method of enlarged section, if the design fails to analyze from the point of view of the overall structure, it is only enlarged for local enlargement, which will cause other parts of the overall structure to form weak layers and cause major damage; The mass and stiffness of the component section will change, and the natural frequency of the structure will also change, and it is very likely to enter the frequency of earthquake or wind shock to produce resonance phenomenon.

(2) Although the construction process of the bonded steel reinforcement method is relatively simple, it can improve the bearing capacity of the structure to a certain extent, but it has higher requirements on the smoothness and cleanliness of the surface of the beam body, and the effectiveness of the reinforcement mainly depends on the bonding material. Strength and durability, and fatigue resistance are not stable enough.

(3) The improvement of structural stiffness by FRP reinforcement is not obvious, and the shear resistance and connection problems are more prominent, and the durability and fire resistance of the bonded surface between FRP material and concrete are poor.

To sum up, traditional reinforcement methods have defects such as insufficient connection reliability between old and new materials, limited improved bearing capacity, and poor durability. It is necessary to close the traffic during the pasting of steel plates, FRP materials and glue curing. This is exactly what the heavy-haul railway operation department is taboo, because the economic loss of the railway will reach hundreds of millions of yuan if the railway is interrupted for one day. After repeated tests, the present invention develops a construction method for strengthening the separated railway bridge. This technology is based on external prestressed reinforcement and self-balancing theory. The prestressed cable is under tension and the concrete is under compression, which can improve the bearing capacity of the original bridge. At the same time, it does not increase the burden on the original bridge, effectively improves the fatigue durability of the bridge, and hardly reduces the clearance height under the original bridge. The construction does not interrupt the traffic, the construction speed is fast, and the cost is low. The cable can be replaced later.

Contents of the invention

Heavy-duty railway bridges are subject to increased dynamic load strength and increased loading frequency, resulting in increased load effects and material stress amplitudes, resulting in shortened service life of existing railway bridges, subgrades and tracks, and structural strength, stiffness, The safety reserve in terms of stability and other aspects has decreased, and the probability of various diseases has increased, and the hazards have intensified.

The purpose of the present invention is to provide a self-balancing external prestressed reinforcement method for bridge structures. The prestressed cables are under tension and the concrete is under compression, which can increase the bearing capacity of the original bridge without increasing the burden on the original bridge; it has the advantages of not affecting the operation of vehicles, The external prestressed tendons can be replaced and stretched multiple times.

The solution of the present invention is to provide a new type of bridge structure self-balancing external prestressing reinforcement technology on the basis of the existing technology. The concrete T beam top plate of the two concrete T beams forms the upper flange of the main beam, and the concrete of the two concrete T beams The bottom plate of the T beam forms the lower flange, which is characterized by: ① interface treatment at the joint of the upper flange of the concrete beam; ② planting reinforcement at the joint of the upper flange of the concrete beam; ③ installation of steel bars at the joint of the upper flange of the concrete beam; ⑤ Increase the diaphragm symmetrically at 2-3m from the end of the beam, and install anchors; ⑥ Pouring concrete at the joint of the upper flange of the main beam, the steering block, and the newly added diaphragm; Stress-reinforced structure. According to a bridge structure self-balancing external prestressing reinforcement method provided by the present invention, the prestressed cables are under tension and the concrete is under compression to form a self-balancing system, which can improve the bearing capacity of the original bridge without increasing the burden of the original bridge; Advantages such as affecting the operation of the vehicle. Especially for the outstanding characteristics of fatigue problems of heavy-duty railway bridges, the external prestressing system can detect and adjust the stress of the cables at any time, check the corrosion of the cables, and repair and replace the cables when necessary. Self-compacting concrete solves the problems of dense reinforcement, complex structure, narrow formwork and original component space caused by aggregate blockage, etc., effectively ensures the compactness of poured concrete, and improves the reinforcement effect. It can be widely used in the reinforcement of heavy-duty railway bridges, concrete box girders, and T-beams. The overall cost is low, economical, safe, and applicable. The project quality is easy to guarantee and has a wide application prospect.

The present invention is also characterized in that the respective upper flanges connecting the separated main girders are an integral structure. After continuous pouring of concrete at the joints of the upper flanges of the separated main girders of the whole bridge, the respective upper flanges of the separated main girders are connected into a whole structure, which can not only increase the bending and torsional rigidity, but also directly bear the tension of the prestressed cables. The tensile force forms an approximately triangular self-balancing system with the external prestressed cables. It not only improves the stiffness and bearing capacity of the main girder, but also increases the transverse integrity of the bridge without increasing the burden on the main girder.

The present invention is also characterized in that a diaphragm is added near the end of the beam. Diaphragms play a vital role in strengthening the horizontal connection of bridges and ensuring the integrity of bridges. It can not only improve the lateral rigidity of the bridge structure, make the lateral load distribution of the bridge structure more reasonable, but also effectively prevent some diseases of the bridge caused by the weakness of the lateral connection. In the present invention, a transverse diaphragm is added near the end of the beam, which can effectively enhance the transverse rigidity.

The present invention is also characterized in that a new diaphragm is added as the anchoring beam of the external prestressed cable. The layout of prestressed pipes at the girder end of the main girder is complicated, and there is no anchorage space for external prestressed cables; the gaps at the ends of the two bridges are narrow, and there is no tension space. Even if there is construction space, the construction is extremely difficult. Using the newly added diaphragm as the anchor beam can easily install external prestressed anchors and tension steel cables, and can also meet the requirements for the horizontal arrangement of steel cables. The newly added diaphragm can bear the huge anchoring force of the external prestressed steel beam, and can transmit the anchoring force of the external prestressed steel beam to the top, bottom and web of the original separated main beam. The external prestressed bridge structure has a huge dependence on the anchorage. The prestress exerted by the steel cable is completely maintained by the anchor point anchorage. , once there is a problem with the anchor component, the consequences will be disastrous, so the external prestressed anchor must provide much higher reliability and safety than the general internal prestressed anchor. These problems can be solved by adopting newly added transverse diaphragms as the anchor beams of external prestressed cables in the present invention.

The present invention is also characterized in that the steering structure of the external prestressed steel bundle is arranged at the diaphragm of the original separated main girder, and either a reinforced concrete structure or a steel structure can be used. The steering device in the external prestressed concrete structure is a special structure. It is the only component connected with the concrete body within the span of the external prestressed cable except for the anchorage structure, and it is responsible for the important task of steel beam steering. One of the most important and critical structural constructions in prestressed concrete structures. The invention combines the original diaphragm to set the steering structure, which can directly transmit the steering force to the top, bottom and web of the separated main beam, and the force is reasonable; and can ensure the position of the external cable, with sufficient strength and reliable Transfer the force of the steel beam.

The present invention is also characterized in that if the reinforced concrete steering structure is adopted, concrete is poured into the connection between the steering block and the lower flange of the main girder to form a whole. In this way, the diaphragm is equivalent to a T-box, which makes good use of the box girder's characteristics of bending resistance, torsional rigidity and integrity that are much better than T-beams. At the same time, it can effectively enhance the horizontal integrity of the bridge. Experimental research and engineering practice show that for railway bridges, train derailment is directly related to the transverse stiffness of the bridge, so the transverse stiffness of the railway bridge must be guaranteed.

The present invention is also characterized in that the ordinary steel bar of the reinforced concrete steering structure is composed of the ring bar of the steering pipe, the closed stirrup and the vertical and horizontal steel bars arranged close to the concrete surface. Among them, the ring bar is the steel bar surrounding a single diversion pipe. Assuming that all the tension is borne by the ring bar, the area of the ring bar surrounding a single diversion pipe can be easily calculated. The vertical and horizontal steel bars are structural steel bars, which are evenly arranged on the concrete surface of the steering structure according to a certain reinforcement ratio. Closed stirrups are closed stirrups that surround all steering pipes, and are also structural reinforcements. Generally, their reinforcement area is equal to the reinforcement area of the ring reinforcement.

The feature of the present invention is that if the steel structure is used as the steering structure, the present invention develops a new type of steel structure steering block, which is composed of I-beam, horizontal connecting system, horizontal connecting system and U-shaped hoop.

The present invention is also characterized in that in the steel structure steering block, according to the longitudinal length of the steel structure steering block, an I-beam is set at an interval of 50cm; the I-beam should be in accordance with the current national standard "Hot Rolled Sectional Steel" GB/T 706-2008 The specified I-beam, and the height is not less than 250mm, and the web thickness is not less than 10mm.

The present invention is also characterized in that in the steering block of the steel structure, a web stiffener is arranged at an interval of 1-1.5m along the longitudinal direction of the I-beam, and angle steels are cross-welded on the web stiffener to form a transverse connection system. The angle steel should adopt the angle steel that conforms to the current national standard "Hot Rolled Section Steel" GB/T 706-2008, and the edge thickness of the angle steel should not be less than 10mm; the angle steel and the web stiffener should be connected by three-sided welding; along the longitudinal interval of the I-beam 1-1.5m, set horizontal connection system on the I-beam roof and bottom plate.

The present invention is also characterized in that in the steel structure steering block, the U-shaped hoop is welded at the bottom of the I-beam. The U-shaped hoop is welded by steel plates, and the steering pipe is arranged through the U-shaped hoop, so that the prestressed steel cable can be fixed.

The present invention is also characterized in that the external cable should adopt the finished cable manufactured by the factory, the finished cable should adopt the steel strand wire or the unbonded steel strand wire with the outer sheath of hot-extruded high-density polyethylene, and the steering gear and the anchorage should be connected with it. matching.

The present invention is also characterized in that the steering gear adopts a cluster type steering gear, which is composed of an inner pipe and an outer steel pipe. The cluster diverter can realize the replaceable design of the whole bundle of steel strands. The dynamic load intensity and frequency of railway bridges are increased, resulting in increased load effects and material stress amplitudes, resulting in shortened service life of existing railway bridges, subgrades and tracks, and the strength, stiffness, and stability of structures. The safety reserves in other aspects have decreased, the probability of various diseases has increased, the hazards have intensified, and the durability and fatigue problems have become prominent. The external prestressing system can detect and adjust the stress of the cable at any time, check the corrosion of the cable, and replace the steel strand when necessary, effectively solving the durability and fatigue problems of the railway bridge.

The invention is also characterized in that the reinforcing concrete used is self-compacting concrete. The self-compacting concrete is mixed by a commercial concrete mixing station. Self-compacting concrete should be tested after mixing, the slump should be 240mm-270mm; the slump expansion should be 600mm-700mm; the U-shaped instrument test height difference Δh is less than 30mm; the V funnel passage time is 4s-25s, thick bone The particle size of the material is 5mm-20mm, the content of needle flakes is less than 10%, and the fineness modulus of the fine aggregate is greater than 2.3. Self-compacting concrete breaks through the limitation of traditional vibrating concrete in forming methods, it can flow freely relying on its own gravity (or only need a slight external force vibration), fill every corner of the formwork through the gap between steel bars, and obtain the required strength and strength after hardening Good durability. Self-compacting concrete not only guarantees the reinforcement effect from the performance of the material, but also guarantees the reinforcement effect from the construction technology.

The present invention is also characterized in that the planting bar spacing in step ② is 25cm-40cm and arranged at equal intervals vertically and horizontally.

The present invention is also characterized in that a reinforcement mesh is installed at half the height of the reinforced concrete at the joint of the upper flange of the concrete beam. The diameter should be 12mm, and the arrangement distance should be half of the distance between planting bars, that is, it should be arranged at equal intervals in vertical and horizontal directions of 12.5cm to 20cm. The concrete height at the joint of the upper flange of the concrete beam is generally 15cm to 25cm. If it is greater than 25cm, two layers of steel mesh should be arranged.

A kind of bridge structure self-balancing external prestressing reinforcement method of the present invention is characterized in that according to the method of the present invention, the operation related to it comprises the following main steps:

Step A: Interface treatment of the upper flange connection of the concrete beam

In said step A, include the following steps:

(1) Remove the paint layer and decorative layer at the joint of the upper flange until the concrete surface is exposed;

(2) If there are initial defects such as voids in the concrete at the connection of the upper flange, the defective parts need to be removed to the dense place;

(3) Chisel the concrete, and the chisel depth is not less than 6mm, and then wash the scum and dust on the surface of the concrete with water;

(4) If the steel bars in the structural reinforcement part are corroded, the steel bars need to be derusted; when the ratio of the corroded area of the steel bars in the structure to the original cross-sectional area exceeds 1/12, the steel bars need to be supplemented.

Step B: Reinforcement at the flange connection of the concrete beam

Its operating points:

(1) When planting bar technology is adopted, the concrete strength grade of the main components of the bridge shall not be lower than C25, and the concrete strength grade of other components shall not be lower than C20.

(2) Grade A glue should be used as the adhesive for bridge planting reinforcement under stress; B grade glue can be used only when the reinforcement is planted according to the structural requirements.

(3) The spacing of the planting bars should be arranged at equal intervals in the vertical and horizontal directions of 25cm to 40cm.

Step C: Install reinforcement at the top flange joint of the concrete beam

Install reinforcement mesh at half of the concrete height at the upper flange connection of the concrete beam. The diameter should be 12mm, and the arrangement distance should be half of the distance between planting bars, that is, it should be arranged at equal intervals in vertical and horizontal directions of 12.5cm to 20cm. The concrete height at the joint of the upper flange of the concrete beam is generally 15cm to 25cm. If it is greater than 25cm, two layers of steel mesh should be arranged.

Step D: Install steering block reinforcement and steering pipes at the bottom of the beam

In said step D, include the following steps:

(1) The steering block of the external cable should be installed at the diaphragm of the separated main beam. The diaphragm and the steering block are jointly stressed, which can have sufficient strength and can reliably transmit the force of the steel beam. The steering pipe should be arranged as close to the web as possible, because this arrangement is more beneficial to the stress of the separated main beam bottom plate and is conducive to the transmission of prestress.

(2) Chisel the concrete at the bottom of the lower flange of the original concrete beam diaphragm, and the chisel depth is not less than 6mm, and then clean the scum and dust on the surface of the concrete with water.

(3) Plant bars on the surface of rough-cut concrete, and the spacing should be arranged at equal vertical and horizontal intervals of 25cm to 40cm.

(4) Arrange ring bars, closed stirrups, and vertical and horizontal bars near the concrete surface. Among them, the ring reinforcement is the reinforcement surrounding a single steering pipe, which can be obtained by a simplified calculation method. Assuming that all the tension is borne by the ring bars, the area of the ring bars surrounding a single diversion duct can be easily calculated. The vertical and horizontal steel bars are structural steel bars, which are evenly arranged on the concrete surface of the steering structure according to a certain reinforcement ratio. Closed stirrups are closed stirrups that surround all steering pipes, and are also structural reinforcements. Generally, their reinforcement area is equal to the reinforcement area of the ring reinforcement.

(5) The steering gear is set at the bottom of the original concrete beam, and adopts a cluster steering gear, which is composed of an inner pipe and an outer steel pipe. The cluster diverter can realize the replaceable design of the whole bundle of steel strands.

The cable steering block outside the body can also adopt a steel structure instead of a common reinforced concrete structure. The invention develops a new steel structure steering block, which is composed of I-shaped steel, horizontal connecting system, horizontal connecting system and U-shaped hoop. The main steps of its construction are:

(1) According to the longitudinal length of the steering block, set an I-beam at an interval of 50cm.

(2) I-beams should adopt I-beams that comply with the current national standard "Hot-rolled Steel" GB/T 706-2008, and the height is not less than 250mm, and the web thickness is not less than 10mm;

(3) A web stiffener is arranged at a longitudinal interval of 1-1.5m along the I-beam, and the angle steel is cross-welded on the web stiffener to form a transverse connection system. The angle steel should adopt the angle steel that conforms to the current national standard "Hot Rolled Section Steel" GB/T706-2008, and the edge thickness of the angle steel should not be less than 10mm; the angle steel and the web stiffener should be connected by three-sided welding.

(4) Set up horizontal connection systems on the top and bottom plates of the I-beam at intervals of 1-1.5m along the longitudinal direction of the I-beam.

(5) Weld the U-shaped hoop at the bottom of the I-beam. The U-shaped hoop is welded by steel plates, and the steering pipe is arranged through the U-shaped hoop, so that the prestressed steel cable can be fixed.

Step E: Increase the diaphragm symmetrically at the distance of 2-3m from the end of the beam, and install the anchor

In said step E, include the following steps:

(1) Chisel the concrete at the joint between the new diaphragm and the original concrete beam, and the chisel depth is not less than 6mm, and then clean the scum and dust on the surface of the concrete with water.

(2) Plant bars on the surface of rough-cut concrete, and the spacing should be arranged at equal vertical and horizontal intervals of 25cm to 40cm.

(3) Lay out the reinforcing bars of the diaphragm, and pay attention to the connection between the reinforcing bars of the diaphragm and the planting bars to enhance the overall workability.

(4) Installation and positioning of external cable anchors. The newly added transverse diaphragm of the present invention can not only enhance the overall working performance, but also serve as an anchoring beam, which is convenient for construction, and can avoid the problem of complicated prestressed anchoring at the beam end of the original main beam and no construction space. The anchor material should meet the requirements of the "Anchors, Clamps and Connectors for Prestressed Steel Beams" (GB/T 14370-2007) standard. Satisfy the requirements of overall bundle change and tension adjustment. The steel pipes used for the anchorage are all seamless steel pipes that meet the requirements of GB8163-87, and other properties of the anchorage should meet the requirements of the GB/T14370-2000 standard.

Step F: Pouring the concrete of the joints of the upper flange of the main girder, the steering block and the newly added diaphragm The concrete adopts self-compacting concrete, including mixing, pouring and curing of self-compacting concrete.

Self-compacting concrete mixing:

Commercial concrete mixing station is used for mixing. Its raw materials are:

(1) Cement: use ordinary 42.5 Portland cement;

(2) Fly ash: Class I fly ash;

(3) Sand: river sand, medium sand, fineness modulus 2.58, qualified for zone II, bulk density 1576kg/m ³ , apparent density 2610kg/m ³ ;

(4) Stone: crushed stone, 5-20mm continuous grading qualified, needle flake content is 9.2%, crushing index 3.4, bulk density 1470kg/m ³ , apparent density 2700kg/m ³ ;

(5) Water reducing agent: high-efficiency water reducing agent, the water reducing rate is greater than 25%.

After the concrete mixing is completed, the slump test, L-type flow meter test, U-type meter test, and V funnel test should be carried out. The test results should meet the following standards: the slump should be controlled at 240mm-270mm; It should be controlled at 600mm~700mm; the height difference Δh of the U-shaped instrument test should be less than 30mm; the passing time of the V funnel should be controlled at 4s~25s.

Self-compacting concrete pours:

(1) Half an hour before pouring, fully wet the original concrete beam and formwork with water;

(2) The pouring of self-compacting concrete can adopt mechanical continuous pouring and manual continuous pouring, and it is recommended to use mechanical continuous pouring. Try to ensure that several consecutive pouring holes are poured at the same time. When pouring, you can use a wooden hammer to slightly tap and vibrate the steel plate. If necessary, use a long drill to insert and tamp properly to ensure the compactness of the poured concrete;

(3) Attention should be paid to the deformation of each part of the structure when pouring, and a reinforcement member should be poured continuously, and the interval time in the middle should not exceed the initial setting time of the concrete;

Self-compacting concrete curing:

After the concrete pouring is completed, it should be watered and cured in time to ensure a 7-14 day curing period: the first 7 days should be watered and cured at least 4 times a day: going to work in the morning, before eating at noon, before eating dinner in the evening, and between 11 and 12 o'clock in the evening. For the next 7 days, apply water for maintenance three times a day in the morning, middle and evening.

Step G: Install and tension the outer cable of the anchor

The material of the outer cable should meet the requirements of "Steel Strands for Prestressed Concrete" (GB/T 5224), "Unbonded Prestressed Steel Strands" (JG 161), "High-density Polyethylene Plastics for Construction Cables" (CJ/T T 3078), "Standards for Seamless Steel Tubes for Structures" (GB/T 8162), "Technical Conditions for Hot-Extruded Polyethylene High-Strength Steel Wire Ropes for Cable-Stayed Bridges" (GB/T 18365), "Special anti-corrosion lubrication for unbonded prestressed tendons Grease" (JG 3007-93) and "Semi-refined Paraffin Wax" (GB 254) and other standards. The external cable should be the finished cable manufactured by the factory, and the finished cable should be the steel strand cable or unbonded steel strand cable with the outer sheath of hot-extruded high-density polyethylene (HDPE), and it should be matched with the steering gear and anchorage.

The above-mentioned technical solution of the present invention has the following advantages compared with traditional reinforcement methods:

(1) A self-balancing external prestressed reinforcement method for bridge structures provided by the present invention, the external cables are arranged at the bottom of the original main girder through the steering block, and self-compacting concrete is poured at the joint of the upper flange of the original main beam, which can fully exert the reinforcing effect of the external cables , and the concrete at the joint of the upper flange can be directly subjected to pre-stressing, so that the bearing capacity of the original bridge is increased without increasing the burden of the original bridge, that is, the self-balancing system.

(2) In the present invention, a transverse diaphragm is added near the end of the beam. Not only can the transverse rigidity of the bridge structure be improved, but also the newly added diaphragm can be used as the anchor beam of the external prestressed cable. The layout of prestressed pipes at the girder end of the main girder is complicated, and there is no anchorage space for external prestressed cables; the gaps at the ends of the two bridges are narrow, and there is no tension space. Even if there is construction space, the construction is extremely difficult. Using the newly added diaphragm as the anchor beam can easily install external prestressed anchors and tension steel cables, and can also meet the requirements for the horizontal arrangement of steel cables.

(3) In the present invention, the steering structure of the externally prestressed steel beam is arranged at the diaphragm of the original separated main beam, and either a reinforced concrete structure or a steel structure can be used. The steering device can not only be installed at the bottom of the beam, but also can be installed at the middle connecting part of two separated main beams for the separated main beam. The linear layout of the external cable elevation can be provided with a horizontal straight line or not, so that different linear layout requirements can be met and the scope of application is wide.

(4) If the present invention adopts the steering structure of reinforced concrete, the junction of the steering block and the lower flange of the main beam is poured with concrete to form a whole. In this way, the diaphragm is equivalent to a T-box, which can effectively enhance the transverse integrity of the bridge.

(5) If the present invention adopts the steering structure of steel structure, a new type of steel structure steering block developed according to the invention is composed of I-beam, horizontal connecting system, horizontal connecting system, and U-shaped hoop. The construction is convenient and fast, and it is economical and applicable.

(6) In view of the outstanding characteristics of railway bridge fatigue problems, the internal prestress cannot be detected and replaced after the grouting. Carry out repairs and exchange cables.

(7) Adopting the self-balancing external prestressing reinforcement technology of the present invention has little influence on the headroom height of the structure and does not affect vehicle traffic. Therefore, the technical method of the present invention is particularly suitable for railway bridges, overpasses and overpasses, and structures with strict requirements on headroom height.

(8) Since the present invention utilizes self-compacting concrete without vibrating and forming during pouring, the present invention solves the problems of cavities caused by aggregate blockage such as dense reinforcement, complex structure, narrow space between formwork and original components, and the like, and It reduces the upper and lower layered honeycomb pockmarks caused by traditional concrete construction due to vibration leakage and over-vibration, improves the quality and durability of concrete, thus greatly simplifies the reinforcement construction process, and makes it possible for ordinary concrete to be constructed. It is especially suitable for For some complex and heterogeneous reinforced structural members, it greatly expands the scope of application.

(9) Since the present invention utilizes the self-compacting concrete technology, the noise pollution in traditional vibrated concrete construction is significantly reduced, and the labor intensity of workers is greatly reduced. At the same time, since the preparation of self-compacting concrete requires a large amount of industrial solid waste such as fly ash, granulated blast furnace slag, and silica fume, it is conducive to the comprehensive utilization of resources and the protection of the ecological environment.

In summary, compared with the prior art, the self-balancing external prestressing reinforcement technology of the present invention combines the self-balancing principle, utilizes the respective advantages of self-compacting concrete and external prestressing, and can effectively improve the stiffness and bearing capacity of existing bridges. At the same time, the original bridge load will not be increased. In view of the outstanding characteristics of fatigue problems of heavy-duty railway bridges, the external prestressing system can detect and adjust the stress of the cables at any time, check the corrosion of the cables, and repair and replace the cables when necessary. Self-compacting concrete solves the problems of dense reinforcement, complex structure, narrow formwork and original component space caused by aggregate blockage, etc., effectively ensures the compactness of poured concrete, and improves the reinforcement effect. It can be widely used in the reinforcement of heavy-duty railway bridges, concrete box girders, and T-beams. The overall cost is low, economical, safe, and applicable. The project quality is easy to guarantee and has a wide application prospect.

Description of drawings

The accompanying drawings are used to provide further understanding of the invention and constitute a part of the specification, and together with the embodiments of the invention, explain the invention. in

Fig. 1 is the elevation view of a prestressed concrete simply supported T-beam bridge for a heavy-duty railway;

Figure 2 is a standard cross-sectional view of a prestressed concrete simply supported T-beam bridge for heavy-duty railways;

Fig. 3 is a sectional view of the transverse diaphragm of a prestressed concrete simply supported T-beam bridge of a heavy-duty railway;

Fig. 4 is a schematic diagram of planting reinforcement and pouring concrete at the joint of the main beam roof;

Figure 5a is a schematic diagram of installation and pouring of the external cable reinforced concrete steering device;

Fig. 5b is a second schematic diagram of installation and pouring of the external cable reinforced concrete steering device;

Figure 6a is a schematic diagram of the first installation of the external cable steel structure steering device;

Fig. 6b is the second installation diagram of the external cable steel structure steering device;

Fig. 7 is a structural diagram of a steel structure steering device;

Figure 8a is a schematic diagram of the facade layout of the structure after reinforcement;

Figure 8b is a second schematic diagram of the facade layout of the structure after reinforcement;

Fig. 9 is a schematic diagram of the installation of the diverter in the middle of the steel beam;

Figure 10 is a large sample diagram of the structure of the steering gear;

The reference signs in the figure are expressed as: 1-concrete T-beam top plate; 2-concrete T-beam web; 3-concrete T-beam bottom plate; 4-diaphragm; 5-roof joint; Cable; 8-new diaphragm; 9-external cable diverter; 10-external cable anchor; 11-HDPE inner tube; 12-outer steel pipe; 13-upper flange reinforced concrete; -Horizontal connection system, 16-horizontal connection system, 17-U-shaped hoop; 18-web stiffener; 19-three-sided surrounding welding.

Detailed ways

Preferred embodiments of the present invention are described below in conjunction with accompanying drawings, wherein reference numerals in the figure represent: 1-concrete T-beam top plate; 2-concrete T-beam web; 3-concrete T-beam bottom plate; 4-diaphragm; 5-The joint of the upper flange; 6-Steering block; 7-External cable; 8-New diaphragm; 9-External cable diverter; 10-External cable anchor; 11-HDPE inner pipe; ; 13-reinforced concrete on the upper flange; 14-I-beam, 15-horizontal connection system, 16-transverse connection system, 17-U-shaped hoop; 18-web stiffener; 19-three-sided surrounding welding.

The solution of the present invention is to provide a bridge structure self-balancing external prestressing reinforcement method on the basis of the prior art. The concrete T beam top plate of the two concrete T beams forms the upper flange of the main beam, and the concrete T of the two concrete T beams The lower flange is formed on the beam bottom plate, which is characterized in that it includes the following steps: A. Interface treatment at the joint of the upper flange of the main beam; B. Planting reinforcement at the joint of the upper flange of the main beam; C. Installing the steel bars at the joint of the upper flange of the main beam; D. Installing the steering at the bottom of the beam E. Symmetrically increase the diaphragm near the beam end and install anchors; F. Pouring the upper flange connection of the main beam and adding concrete for the diaphragm; G. Installing and tensioning the outer cable of the anchor body to obtain a self-balancing body Prestressed reinforced structure.

The present invention is also characterized in that by planting reinforcement at the bottom of the upper flange of the main girder, pouring self-compacting concrete at the junction of the upper flanges of the two main girders, the outer cables are arranged at the bottom of the main beam, and the concrete at the junction of the upper flanges and the outer prestressed cables form an approximately triangular self-compacting concrete structure. Balanced system, the main girder includes the existing T girder, concrete box girder, hollow slab girder, common reinforced concrete girder or prestressed concrete girder.

The present invention is also characterized in that a transverse diaphragm is newly added near the beam end 2-3m.

The present invention is also characterized in that a new diaphragm is used as the anchor beam of the external prestressed cable, and the anchorage of the external prestressed cable is arranged in the newly added diaphragm.

The present invention is also characterized in that the steering structure of the externally prestressed steel beam is arranged at the diaphragm of the original separated main girder.

The present invention is also characterized in that the steering device of the external prestressed steel tendon adopts a reinforced concrete structure or a steel structure, and the steering device is installed at the bottom of the beam, or for a separated main beam, it is installed at the middle connecting part of two separated main beams , or set the horizontal straight line segment for the linear layout of the external cable elevation.

The present invention is also characterized in that if the external prestressed beam steering device adopts a reinforced concrete structure, step D includes the construction step of installing ordinary steel bars for the steering block, and step F includes the construction step of pouring the steering block concrete.

The present invention is also characterized in that the connection between the steering block and the lower flange of the main girder diaphragm is poured with concrete to form a whole.

The present invention is also characterized in that the ordinary steel bar of the reinforced concrete steering structure is composed of the ring bar of the steering pipe, the closed stirrup and the vertical and horizontal reinforcement arranged near the concrete surface. , according to a certain reinforcement ratio, it is evenly arranged on the concrete surface of the steering structure. The closed stirrup is a closed stirrup that surrounds all the steering pipes. It belongs to the structural reinforcement, and its reinforcement area is equal to the reinforcement area of the ring reinforcement.

The present invention is also characterized in that if the external prestressed steel bundle steering device adopts a steel structure, the steel structure steering device is composed of an I-beam, a horizontal connection system, a horizontal connection system and a U-shaped hoop.

The present invention is also characterized in that according to the longitudinal length of the steel structure steering device, an I-beam is set at an interval of 50 cm, and the I-beam adopts the I-beam that meets the current national standard "Hot-rolled Sectional Steel" GB/T 706-2008, and The height is not less than 250mm, and the web thickness is not less than 10mm.

The present invention is also characterized in that a web stiffener is arranged at a longitudinal interval of 1-1.5m along the I-beam, and the angle steel is cross-welded on the web stiffener to form a transverse connection system. The angle steel specified in /T 706-2008, and the side thickness of the angle steel should not be less than 10mm, the angle steel and the web stiffener shall be connected by three-sided welding, and the horizontal connection shall be arranged on the top and bottom plates of the I-beam at an interval of 1-1.5m along the longitudinal direction of the I-beam Tie.

The present invention is also characterized in that U-shaped hoops are welded at the bottom of the I-beam, and the U-shaped hoops are welded by steel plates, and the steering pipe is arranged through the U-shaped hoops to fix external prestressed steel beams.

The present invention is also characterized in that the external prestressed cable adopts the finished cable manufactured by the factory, and the finished cable adopts the steel strand wire or the unbonded steel strand wire with the outer sheath of hot-extruded high-density polyethylene, and the steering gear and the anchorage are matched with it. The steering gear adopts a cluster steering gear, which is composed of an inner tube and an outer steel tube.

The present invention is also characterized in that the concrete is self-compacting concrete, and the self-compacting concrete is mixed by a commercial concrete mixing station, and its raw materials are: cement: ordinary 42.5 Portland cement; fly ash: Class I fly ash ; Sand: river sand, medium sand, fineness modulus 2.58, qualified for grading in Zone II, bulk density 1576kg/m ³ , apparent density 2610kg/m ³ ; stone: crushed stone, 5-20mm continuous grading qualified, needle The flake content is 9.2%, the crush index is 3.4, the bulk density is 1470kg/m ³ , and the apparent density is 2700kg/m ³ ; water reducing agent: high-efficiency water reducing agent, the water reducing rate is greater than 25%.

The present invention is also characterized in that the self-compacting concrete is tested after mixing, and the slump should be 240mm-270mm; the slump expansion should be 600mm-700mm; the height difference Δh of the U-shaped instrument test is less than 30mm; the passing time of the V funnel is 4s ～25s, the particle size of coarse aggregate is 5mm～20mm, the needle flake content is less than 10%, and the fineness modulus of fine aggregate is greater than 2.3.

The present invention is also characterized in that the planting bar spacing in step B is 25 cm to 40 cm and arranged at equal intervals vertically and horizontally.

The present invention is also characterized in that steel mesh is installed at half the height of reinforced concrete at the joint of the upper flange of the concrete beam. The height of the concrete is generally 15cm to 25cm. If it is greater than 25cm, two layers of steel mesh should be arranged.

The specific embodiment is a heavy-duty railway prestressed simply supported T-beam bridge, and the self-balancing prestressed reinforcement technology according to the present invention comprises the following steps:

Step A: 5 interface treatment at the joint of the upper flange of the concrete T-beam

Fig. 1 is the elevation view of the prestressed concrete simply supported T-beam bridge of the heavy-duty railway; there are five transverse beams between the concrete T-beam top plate 1 and the concrete T-beam bottom plate 3 of the prestressed concrete simply-supported T-beam bridge as shown in Fig. 1 The diaphragm 4 and the transverse diaphragm 4 are arranged perpendicular to the web 2 of the concrete T beam. The prestressed concrete simply supported T-beam bridge shown in Fig. 1 includes two different sections: a common section and a section with a transverse diaphragm.

Fig. 2 is a standard section view of a prestressed concrete simply supported T-beam bridge for heavy-duty railways;

Fig. 3 is a sectional view of the diaphragm of a prestressed concrete simply supported T-beam bridge of a heavy-duty railway; As a whole, the annular diaphragm 4 is perpendicular to the concrete T-beam top plate 1 , the concrete T-beam web 2 and the concrete T-beam bottom plate 3 of the two concrete T-beams at the same time.

In said step A, include the following steps:

Figure 4 is a schematic diagram of planting reinforcement and pouring concrete at the joint of the main beam roof; as shown in Figure 4,

(1) The lower part of the concrete T beam top plate 1 of the section between the two concrete T beam webs 2 of the two concrete T beams is the joint 5 of the upper flange of the T beam, and the paint layer and the decorative layer of the joint 5 of the upper flange are removed until exposed concrete surfaces;

(2) If there are initial defects such as voids in the concrete at the joint 5 of the upper flange, the defective parts need to be removed to the dense place;

(3) Chisel the bottom surface of the upper flange joint 5, and the chisel depth is not less than 6mm, and then clean the scum and dust on the concrete surface with water;

(4) If the steel bars in the structural reinforcement part are corroded, the steel bars need to be derusted; when the ratio of the corroded area of the steel bars in the structure to the original cross-sectional area exceeds 1/12, the steel bars need to be supplemented.

Step B: Plant reinforcement on the concrete surface at the junction of the upper flange of the concrete T-beam 5

Its operating points:

(1) When planting bar technology is adopted, the concrete strength grade of the main components of the bridge shall not be lower than C25, and the concrete strength grade of other components shall not be lower than C20.

(2) Grade A glue should be used as the adhesive for bridge planting reinforcement under stress; B grade glue can be used only when the reinforcement is planted according to the structural requirements.

(3) The spacing of the planting bars should be arranged at equal intervals in the vertical and horizontal directions of 25cm to 40cm.

Step C: Install common reinforcement at flange junction 5 of the concrete T-beam

Fig. 4 is a schematic diagram of planting bars and pouring concrete at the joint of the main beam top plate; The diameter should be 12mm, and the arrangement distance should be half of the distance between planting bars, that is, it should be arranged at equal intervals in vertical and horizontal directions of 12.5cm to 20cm. The height of the reinforced concrete 13 on the upper flange of the T-beam is generally 15cm to 25cm, and if it is greater than 25cm, two layers of reinforcement mesh must be arranged.

Step D: Install the steel bars of the steering block 6 and the external cable steering device 9 at the bottom of the T beam

According to the present invention, the steering block 6 can adopt either a reinforced concrete structure or a steel structure. Figure 5a is a schematic diagram of the installation and pouring of the external cable reinforced concrete steering device; Figure 5b is a schematic diagram of the installation and pouring of the external cable reinforced concrete steering device; as shown in Figures 5a and 5b,

In said step D, include the following steps:

(1) The outer cable steering block 6 is installed at the separated main beam diaphragm 4, and the diaphragm 4 and the steering block 6 are jointly stressed, which can have sufficient strength and can reliably transmit the force of the steel beam.

(2) Chisel the concrete at the bottom of the lower flange of the original concrete beam diaphragm 4, and the chisel depth is not less than 6mm, and then clean the scum and dust on the concrete surface with water.

(3) Plant bars on the surface of rough-cut concrete, and the spacing should be arranged at equal vertical and horizontal intervals of 25cm to 40cm.

(4) Arrange ring bars, closed stirrups, and vertical and horizontal bars near the concrete surface.

(5) The external cable diverter 9 is arranged at the bottom of the original concrete beam, and a cluster diverter is used. Figure 7 is a schematic diagram of the installation of the diverter in the middle of the steel beam; as shown in Figure 7, according to the linear arrangement of the outer cable 7, the outer cable diverter 9 is pre-embedded in the steering block 6. Figure 9 is a schematic diagram of the installation of the diverter in the middle of the steel beam; Figure 10 is a large-scale diagram of the structure of the diverter;

(6) Fig. 5b is a schematic diagram of installation and pouring of the reinforced concrete steering device for external cables; Various linear layout requirements of the external cable 7 can be met.

If the cable turning block 6 outside the body adopts steel structure, develop a kind of novel steel structure turning block according to the present invention, be made up of I-beam 14, horizontal connecting system 15, transverse connecting system 16, U-shaped hoop 17. Figure 6a is a schematic diagram of the installation of the steel structure steering device with external cables; Figure 6b is a schematic diagram of the installation of the steel structure steering device with external cables; Figure 7 is a structural diagram of the steel structure steering device; as shown in Figures 6a, 6b and 7,

The main steps of its construction are:

(1) According to the longitudinal length of the steering block 6, an I-beam 14 is arranged at an interval of 50 cm. The steering block 6 of this embodiment is made up of two I-beams 14 .

(2) The I-beam 14 should adopt the I-beam conforming to the current national standard "Hot Rolled Steel" GB/T 706-2008, and the height is not less than 250mm, and the web thickness is not less than 10mm. The height of the I-beam 14 selected in this embodiment is 300 mm, and the thickness of the web is 13 mm.

(3) Figure 7 is a structural diagram of a steel structure steering device; as shown in Figure 7, a web stiffener 18 is arranged along the I-beam 14 at a longitudinal interval of 1-1.5m, and the angle steel is cross-welded on the web stiffener 18 to form a transverse direction Link 16. The angle steel should adopt the angle steel that conforms to the current national standard "Hot Rolled Section Steel" GB/T 706-2008, and the edge thickness of the angle steel should not be less than 10mm; the angle steel and the web stiffener 18 are connected by three-sided welding. The lateral width of the steering block 6 of this embodiment is 2880mm, and the web stiffeners 18 are arranged at intervals of 1m along the I-beam 14 longitudinally, the thickness of the web stiffeners 18 is 10mm, and the edge thickness of the angle steel is 10mm, as shown in Figure 7 , the welding mode of the angle steel and the web stiffener 18 is three-sided welding 19 .

(4) Fig. 7 is a structural diagram of a steel structure steering device; as shown in Fig. 7 , a horizontal connection system 15 is arranged on the top and bottom of the I-beam 14 at intervals of 1-1.5m along the longitudinal direction of the I-beam 14 . In this embodiment, steel plates with a thickness of 10 mm are welded at a longitudinal interval of 1 m to form a horizontal connection system 15 .

(5) Weld the U-shaped hoop 17 at the bottom of the I-beam 14 . U-shaped hoop 17 is welded by steel plate, and steering pipe passes through U-shaped hoop 17 and is arranged, so that outer cable 7 can be fixed.

(6) Same as the reinforced concrete steering structure, Fig. 6b is the second installation diagram of the steering device of the outer cable steel structure; as shown in Fig. 6b, according to the method of the present invention, the outer cable steering block 6 of the steel structure can also be arranged in two separate The middle connecting part of the type main girder can meet various linear layout requirements of the cable 7 outside the body like this.

Step E: Pouring a new diaphragm 8 at a distance of 2m from the end of the beam, and installing the external cable anchor 10. The step E includes the following steps:

(1) Chisel the concrete at the joint between the newly added diaphragm 8 and the original concrete beam, and the chisel depth is not less than 6mm, and then clean the scum and dust on the concrete surface with water.

(2) Plant bars on the surface of rough-cut concrete, and the spacing should be arranged at equal vertical and horizontal intervals of 25cm to 40cm.

(3) Arrange the reinforcing bars of the newly added diaphragm 8. Note that the reinforcing bars of the newly added diaphragm 8 should be connected with the planting bars to enhance the overall workability.

(4) The external cable anchor 10 is installed and positioned. Fig. 8a is a schematic diagram of the structural facade layout after reinforcement; Fig. 8b is a schematic diagram of the structural facade layout after reinforcement; According to the invention, the newly added diaphragm 8 can not only enhance the overall working performance, but also can be used as an anchoring beam, which is convenient for construction, and can avoid the problem of complicated prestressed anchoring at the beam end of the original main beam and no construction space.

Step F: Pouring the concrete of the T-beam upper flange connection 5, the steering block 6 and the new diaphragm 8

Figure 8a is a schematic diagram of the structural facade layout after strengthening; Figure 8b is a schematic diagram of the structural facade layout after strengthening; Concrete adopts self-compacting concrete, including self-compacting concrete mixing, pouring and curing.

Self-compacting concrete mixing:

Commercial concrete mixing station is used for mixing. Its raw materials are:

(1) Cement: use ordinary 42.5 Portland cement;

(2) Fly ash: Class I fly ash;

(3) Sand: river sand, medium sand, fineness modulus 2.58, qualified for zone II, bulk density 1576kg/m ³ , apparent density 2610kg/m ³ ;

(4) Stone: crushed stone, 5-20mm continuous grading qualified, needle flake content is 9.2%, crushing index 3.4, bulk density 1470kg/m ³ , apparent density 2700kg/m ³ ;

(5) Water reducing agent: high-efficiency water reducing agent, the water reducing rate is greater than 25%.

After the concrete mixing is completed, the slump test, L-type flow meter test, U-type meter test, and V funnel test should be carried out. The test results should meet the following standards: the slump should be controlled at 240mm-270mm; It should be controlled at 600mm~700mm; the height difference Δh of the U-shaped instrument test should be less than 30mm; the passing time of the V funnel should be controlled at 4s~25s.

Self-compacting concrete pours:

(1) Half an hour before pouring, fully wet the original concrete beam and formwork with water;

(2) The pouring of self-compacting concrete can adopt mechanical continuous pouring and manual continuous pouring, and it is recommended to use mechanical continuous pouring. Try to ensure that several consecutive pouring holes are poured at the same time. When pouring, you can use a wooden hammer to slightly tap and vibrate the steel plate. If necessary, use a long drill to insert and tamp properly to ensure the compactness of the poured concrete;

(3) Attention should be paid to the deformation of each part of the structure when pouring, and a reinforcement member should be poured continuously, and the interval time in the middle should not exceed the initial setting time of the concrete;

Self-compacting concrete curing:

After the concrete pouring is completed, it should be watered and cured in time to ensure a 7-14 day curing period: the first 7 days should be watered and cured at least 4 times a day: going to work in the morning, before eating at noon, before eating dinner in the evening, and between 11 and 12 o'clock in the evening. For the next 7 days, apply water for maintenance three times a day in the morning, middle and evening.

Step G: Installing and Tensioning the Outer Cable of the Anchor 7

Fig. 8a is a schematic diagram of the facade layout after strengthening; Fig. 8b is a schematic diagram of the facade layout of the reinforced structure; As shown in Figure 8a; a triangular arrangement can also be used, as shown in Figure 8b. The steering block of the outer cable 7 can be arranged at the bottom of the beam, as shown in Figures 5a and 6a; it can also be arranged at the middle connecting part of two separated main beams, as shown in Figures 5b and 6b. In this way, according to the method for arranging the outer cables 7 provided by the present invention, it is possible to conveniently and flexibly arrange the line shape, lateral position, and number of steel bundles of the outer cables 7 .

The tensile force in the present invention is directly borne by the concrete at the joint of the upper flange 5, and a self-balancing system is formed between the external cable 7 and the concrete at the joint 5 of the upper flange, which can fully exert the reinforcing effect of the external cable 7 without compromising Increase the burden on the existing concrete T-beams.

The material of the outer cable 7 should meet the requirements of "Steel Strands for Prestressed Concrete" (GB/T 5224), "Unbonded Prestressed Steel Strands" (JG 161), "High-density Polyethylene Plastics for Construction Cables" (CJ /T 3078), "Standards for Seamless Steel Tubes for Structures" (GB/T 8162), "Technical Conditions for Hot-Extruded Polyethylene High-Strength Steel Wire Ropes for Cable-Stayed Bridges" (GB/T 18365), "Special Anti-corrosion for Unbonded Prestressed Tendons" Grease" (JG 3007-93) and "Semi-refined Paraffin Wax" (GB 254) and other standards. The outer cable 7 of this embodiment adopts the finished cable manufactured by the factory, and is matched with the outer cable diverter 9 and the outer cable anchor 10 .

It is easy to understand that although the present invention is described above in conjunction with a T-beam bridge, the present invention can be equally applied to other structural forms, such as concrete box girders, hollow slab girders, small box girders in highways, and the like.

Finally, it should be noted that: the specific real-time modes described above are only preferred implementations of the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can modify the technical solutions described in the aforementioned embodiments, or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (10)

1. bridge construction self-balancing external prestressing strengthening method is characterized in that may further comprise the steps:

A, junction, girder top flange interface processing;

B, the junction bar planting of girder top flange;

C, installation junction, girder top flange reinforcing bar;

Steering block is installed at the bottom of D, the beam and is turned to pipeline;

E, increase diaphragm, ground tackle is installed near beam-ends symmetry;

F, cast junction, girder top flange, newly-increased diaphragm concrete;

G, installation, stretch-draw anchor external tendon obtain the structure of self-balancing external prestressing strengthening.

2. a kind of bridge construction self-balancing external prestressing strengthening method according to claim 1; It is characterized in that through bottom bar planting in the girder top flange; Junction, two girder top flanges cast self-compacting concrete; External tendon is arranged in the girder bottom, and junction, top flange concrete and external prestressing tendon form subtriangular self equilibrium systems, and said girder comprises T beam, concrete box girder, hollow slab beam, normal reinforced concrete beam or the prestressed concrete beam that has existed.

3. a kind of bridge construction self-balancing external prestressing strengthening method according to claim 1 is characterized in that the newly-increased diaphragm near beam-ends 2-3m place.

4. a kind of bridge construction self-balancing external prestressing strengthening method according to claim 1 is characterized in that the anchoring crossbeam of newly-increased diaphragm as external prestressing tendon, and the ground tackle of external prestressing tendon is arranged in the newly-increased diaphragm.

5. a kind of bridge construction self-balancing external prestressing strengthening method according to claim 1 is characterized in that the steering structure of external prestressing steel bundle is arranged on the diaphragm place of original separate type girder.

6. a kind of bridge construction self-balancing external prestressing strengthening method according to claim 1; The transfer that it is characterized in that external prestressing steel bundle adopts reinforced concrete structure or adopts steel work not have; Transfer is installed at the bottom of the beam; Perhaps be installed in the middle interconnecting piece position of two separate type girders for the girder of separate type, perhaps the linear layout of external tendon facade is provided with the straight horizontal line segment.

7. a kind of bridge construction self-balancing external prestressing strengthening method according to claim 1; It is characterized in that external prestressing steel bundle transfer if adopt reinforced concrete structure; In step D, comprise the construction sequence that the steering block plain bars is installed, in step F, comprise cast steering block Concrete Construction step.

8. a kind of bridge construction self-balancing external prestressing strengthening method according to claim 7, it is characterized in that steering block and junction, girder diaphragm bottom flange together fluid concrete form integral body.

9. a kind of bridge construction self-balancing external prestressing strengthening method according to claim 8; It is characterized in that steel concrete steering structure plain bars is by the ring muscle that turns to pipeline, the stirrup and forming to reinforcing bar in length and breadth near what concrete surface was arranged of remaining silent; The ring muscle is to surround the single reinforcing bar that turns to pipeline; Be distributing bar to reinforcing bar in length and breadth, evenly arrange at the steering structure concrete surface that the stirrup of remaining silent is to surround the stirrup of remaining silent that all turn to pipeline by certain reinforcement ratio; Belong to distributing bar, its area of reinforcement equals to encircle the area of reinforcement of muscle.

10. according to the described a kind of bridge construction self-balancing external prestressing strengthening method of arbitrary claim in the claim 1 to 5; It is characterized in that external prestressing steel bundle transfer if adopt steel work, the steel work transfer is made up of i beam, horizontal coupled system, sway bracing and U type hoop; Perhaps according to the longitudinal length of steel work transfer, 50cm is provided with an i beam at interval, and i beam adopts the i iron that meets national current standard " hot-rolled steel section " GB/T 706-2008 regulation, and highly is not less than 250mm, and web thickness is not less than 10mm; Perhaps the web stiffening rib is set one along i beam longitudinal separation 1-1.5m; The angle steel intersection is welded on the web stiffening rib and forms sway bracing; Angle steel should adopt the angle steel that meets national current standard " hot-rolled steel section " GB/T 706-2008 regulation; And the limit thickness of angle steel should not be less than 10mm, and angle steel and web stiffening rib are taked three weld all around connected modes, at the i beam roof and floor horizontal coupled system is set along i beam longitudinal separation 1-1.5m; Perhaps at the bottom of i beam welding U type hoop, U type hoop is welded by steel plate, and turn to pipeline to pass U type hoop and arrange, thus the outer prestressed strand of fixed body; Perhaps external prestressing tendon adopts plant-manufactured finished product rope; The finished product rope adopts the steel strand rope or the non-bending steel cable rope of hot extrude high density polyethylene (HDPE) oversheath; Steering gear and ground tackle are supporting with it, and the cluster type steering gear is adopted in steering gear, are made up of interior pipe and outer steel pipe; Perhaps said concrete is a self-compacting concrete, and the self-compacting concrete system of mixing adopts the commercial concrete agitator to stir, and its raw material are: (1) cement: adopt common 42.5 portland cements; (2) flyash: I level flyash; (3) sand: river sand, medium sand, fineness modulus 2.58, II district grating is qualified, bulk density 1576kg/m ³, apparent density 2610kg/m ³(4) stone: rubble, the 5-20mm continuous grading is qualified, and faller gill shape content is 9.2%, crush index 3.4, bulk density 1470kg/m ³, apparent density 2700kg/m ³(5) water reducing agent: high efficiency water reducing agent, water-reducing rate is greater than 25%; Detect after perhaps the self-compacting concrete system of mixing is accomplished, the slump should be at 240mm～270mm; The slump divergence is at 600mm～700mm; U type appearance test difference in height Δ h is less than 30mm; The V funnel passes through the time at 4s～25s, and coarse aggregate size is 5mm～20mm, and faller gill shape content is less than 10%, and the fineness modulus of fines is greater than 2.3; Perhaps the bar planting spacing in step B is that 25cm～40cm is in length and breadth to equidistant layout; Perhaps mounting reinforcing steel bars net at reinforced concrete mid-height place, junction, concrete beam top flange; Diameter adopts 12mm; Arrange that distance is preferably the half the of bar planting distance; In length and breadth to equidistant layout, junction, concrete beam top flange concrete height is generally 15cm～25cm according to 12.5cm～20cm, if need arrange two-layer steel mesh reinforcement greater than 25cm.

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