CN102587296B - Self-balancing external prestressing strengthening method for bridge structure - Google Patents

Self-balancing external prestressing strengthening method for bridge structure Download PDF

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CN102587296B
CN102587296B CN 201210039845 CN201210039845A CN102587296B CN 102587296 B CN102587296 B CN 102587296B CN 201210039845 CN201210039845 CN 201210039845 CN 201210039845 A CN201210039845 A CN 201210039845A CN 102587296 B CN102587296 B CN 102587296B
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China
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concrete
external prestressing
self
steel
flange
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CN 201210039845
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Chinese (zh)
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CN102587296A (en
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薛继连
余志武
谈遂
李进洲
蒋丽忠
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朔黄铁路发展有限责任公司
中南大学
高速铁路建造技术国家工程实验室
湖南中大建科土木科技有限公司
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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 kind of bridge construction self-balancing external prestressing strengthening method
Technical field
The present invention relates to bridge and the Structural Engineering field of building subject, be specifically related to a kind of reinforcing intensifying method and construction technology of bridge superstructure, especially the quick strengthening of heavily loaded railroad bridge promoted.
Background technology
Along with at a high speed with the deepening continuously of passenger dedicated railway line Large scale construction, China railways at a high speed and fast passenger transportation network progressively forms, " separating lines for passenger and freight ", both wired take start goods train and will become the Main Patterns of China Railway as the means of transportation of leading.Therefore, the heavy duty of Existing Railway Bridges transformation reinforcing is one of current problem demanding prompt solution of China railways with assessment.
The heavy haul railway conveying capacity is large, and economic and social benefit is remarkable, and the Development of Railway heavy haul transport has become the direction of countries in the world Transportation Development, is also the main path that China accelerates to improve railway transport capacity.Accelerate coal transport facility construction and both wired capacity expansion revamping dynamics, form that transport power is powerful, the Coal Transport system of tissue advanced person, perfect in shape and function is one of important development content of China's Mid-term and Long-term Plan of the Railway Network.Guarantee that heavy haul railway runs efficiently and safely, each key element that forms the heavy haul railway system must keep high standard, the distinctive high rate of traffic flow of China in addition, and this has higher requirement to China's heavy haul railway technology.
Railway heavy haul transport is a comprehensive system engineering, involves the overall process of Railway Design, construction, operation and maintenance.Heavy haul railway is that the suffered dynamic load intensity of bridge, roadbed strengthens with the main difference of general railway, the stand under load increase frequency, cause that load effect strengthens, the material stress width strengthens, cause shorten the application life of Existing Railway Bridges and roadbed and track, the safety stock of the aspects such as the intensity of structure, rigidity, stability descends, and the probability that various diseases occur strengthens, the harmfulness aggravation.Through heavy service in a few years, the fracture of bridge diaphragm, beam body crackle, pier rhegma, beam-ends dieback, bearing inclination, culvert rhegma, culvert distortion have been produced and bridges and culverts changeover portion subgrade settlement, interval embankment and cutting location sink, shoulder width is not enough, bedding is risen soil and the polytype diseases such as plate knot of ballast bed, impeded drainage as China's Datong-Qinhuangdao Railway, north yellow line.Along with improving constantly and the continuous increase of rate of traffic flow of the heavy increasing of China railways heavy haul transport axle, traction quality, the service condition of Existing Railway Bridges and roadbed will worsen more, and the probability that bridge and subgrade defect produce will further strengthen.
Along with the continuous increase of freight volume, the various diseases of bridge become increasingly conspicuous, and functional performance constantly descends, and especially span is that 32.0m prestressed concrete split blade type beam is on the weak side because of transverse splicing, and the diaphragm phenomenon of rupture exacerbates year by year.When train passes through, indivedual bridges have even occurred because swinging the de-phenomenon of bending of the contact net caused too greatly.In order to guarantee transportation safety, guarantee the normal operating condition of equipment, meet the ever-increasing needs of freight volume, must be reinforced bridge.For this class beam body, how effectively to take reinforcement measure to promote its rigidity, intensity and fatigue durability and become the problem that railway transport administration department extremely pays close attention to.
In bridge engineering, reinforcement means commonly used has reinforcement method of enlarging section, reinforcement by sticking of sheets, FRP material strengthening with external bonding method, change structure force path reinforcing method and reinforced with external steel encased etc. at present.Be subject to the impact of form of structure or material behavior, these traditional reinforcement means all have certain limitation.
(1) while adopting reinforcement method of enlarging section, if fail to analyze from integrally-built angle in design, only for part, strengthen, can cause like this overall structure other parts to form weak floor and great destruction occurs; Strengthen member section, its quality and rigidity will change, and the intrinsic frequency of structure also changes thereupon, probably enter into the frequency of earthquake or wind shake and produce covibration.
(2) although the reinforcement by sticking of sheets construction technology is simpler, can improve to a certain extent the bearing capacity of structure, but beam surface planeness, cleannes are had relatively high expectations, and the validity of reinforcing depends primarily on intensity and the durability of binding material, anti-fatigue performance is also stable not.
(3) the FRP reinforcing is not obvious to the raising of the rigidity of structure, and shearing resistance and connectivity problem are all more outstanding, and between FRP material and concrete, durability and the fireproof performance of adhesive surface is poor.
In sum, there are the defects such as new and old bi-material connection reliability bearing capacity not enough, that improve is limited, durability is poor in traditional reinforcement means.Need close traffic at affixing steel plate, FRP material and glue setting up period, this exactly heavy haul railway operation department abstain from because railway interrupts one day, its economic loss will reach more than one hundred million units.The present invention has developed a kind of job practices of railway separate type bridge being carried out to intensive treatment through repetition test, this technology is based on external prestressing strengthening and self-balancing theory, the prestressed cable tension, concrete compression, can, when promoting former bridge bearing ability, not increase former bridge burden, effectively improve the fatigue durability of bridge, and reduce hardly former bridge under-clearance height, and the construction uninterrupted traffic, speed of application is fast, cost is low, and the later stage can be changed rope.
Summary of the invention
The suffered dynamic load intensity of heavy haul railway bridge strengthens, the stand under load increase frequency, cause that load effect strengthens, the material stress width strengthens, cause shorten the application life of Existing Railway Bridges and roadbed and track, the safety stock of the aspects such as the intensity of structure, rigidity, stability descends, and the probability that various diseases occur strengthens, the harmfulness aggravation.
The object of the present invention is to provide a kind of bridge construction self-balancing external prestressing strengthening method, the prestressed cable tension, concrete compression, can, when promoting former bridge bearing ability, not increase former bridge burden; Have do not affect vehicle operating, the external prestressing muscle can be changed and the advantage such as stretch-draw repeatedly.
Solution of the present invention is on the basis of existing technology, a kind of novel bridge structure self-balancing external prestressing strengthening technology is provided, the concrete T-shaped beam top board of two concrete T-shaped beams forms the girder top flange, the concrete T-shaped beam base plate of two concrete T-shaped beams forms bottom flange, it is characterized in that: 1. junction, concrete beam top flange interface processing; 2. junction, concrete beam top flange bar planting; 3. junction, concrete beam top flange reinforcing bar is installed; 4. the steering block reinforcing bar is installed at the bottom of beam and is turned to pipeline; 5. apart from the symmetrical diaphragm that increases in beam-ends 2-3m place, ground tackle is installed; 6. pour into a mould junction, girder top flange, steering block and newly-increased diaphragm concrete; 7. install, the stretch-draw anchor external prestressing tendon, obtain the structure of self-balancing external prestressing strengthening.According to a kind of bridge construction self-balancing external prestressing strengthening method provided by the invention, the prestressed cable tension, concrete compression, form self equilibrium systems, can, when promoting former bridge bearing ability, not increase former bridge burden; There is advantages such as not affecting vehicle operating.Special for the outstanding characteristics of heavy haul railway bridge fatigue problem, external prestressing system can detect at any time, the stress of adjustment rope, checks the corrosion condition of rope, can also be keeped in repair where necessary, change rope.Self-compacting concrete has solved that arrangement of reinforcement is intensive, complex structure, template and former member narrow space etc. are because aggregate blocks the problems such as cavity that cause, and effectively guarantees the fluid concrete compactness, has improved consolidation effect.Can be widely used in heavy haul railway bridge, concrete box girder, the reinforcing of T beam, overall cost is low, economic, safety, applicable, and workmanship is easy to assurance, and application prospect is extensive.
It is an overall structure that feature of the present invention also is to connect separate type girder top flange separately.After the concrete of junction, full-bridge continuous pouring separate type girder top flange, the separate type girder, top flange separately is connected to an overall structure, not only can increase bending resistance and torsional rigidity, can also directly bear the stretching force of prestressed cable, with external prestressing tendon, form subtriangular self equilibrium systems.Both improve girder rigidity and bearing capacity, increased the bridge lateral globality, do not increased again the girder burden.
Feature of the present invention also is increasing diaphragm newly near the beam-ends place.Diaphragm is playing vital effect aspect the globality of the lateral ties of strengthening bridge, assurance bridge.Not only can improve the lateral stiffness of bridge construction, make the load cross direction profiles of bridge construction be tending towards more reasonable, can also effectively prevent some diseases that bridge causes due to the weakness of lateral ties.The present invention, near the newly-increased diaphragm in beam-ends place, can effectively strengthen lateral stiffness.
Feature of the present invention also is the anchoring crossbeam of newly-increased diaphragm as external prestressing tendon.Girder beam-ends prestress pipe complicated layout, do not have the anchoring space of external prestressing tendon; Two bridge end gaps are narrow, also there is no the stretch-draw space, even there is construction space, difficulty of construction is also large especially.Adopt newly-increased diaphragm as anchoring crossbeam fixing body External prestressed ground tackle and stretch-draw cable wire easily, also can meet the requirement of cable wire in lateral arrangement.Newly-increased diaphragm can bear the anchored force that external prestressing tendon is huge, the anchored force of external prestressing tendon can be delivered in the roof and floor and web of original separate type girder again.The external prestressing bridge construction has huge dependence to ground tackle, the prestressing force that cable wire applies relies on the anchor point ground tackle to keep fully, external prestressing is asked for and is born than the more disadvantageous dynamic load of prestressing with bond muscle and produce thus fatigue problem simultaneously, once the ground tackle assembly goes wrong, its consequence caused is catastrophic, so the external prestressing ground tackle must provide reliability and the safety more much higher than general prestressing with bond ground tackle.The present invention takes newly-increased diaphragm can address these problems as the anchoring crossbeam of external prestressing tendon.
Feature of the present invention also is that the steering structure of external prestressing tendon is arranged on the diaphragm place of original separate type girder, both can adopt reinforced concrete structure, also can adopt steel work.Transfer in the externally pre-stressed concrete structure is a kind of special tectonic, it is except anchoring structure, external prestressing tendon is across interior unique and the associated member of concrete bodies, and bearing the vital task that the steel bundle turns to, is also one of Structural Tectonics of most important in the externally pre-stressed concrete structure, most critical.The present invention arranges steering structure in conjunction with original diaphragm, steering force can be directly passed to roof and floor and the web of separate type girder, reasonable stress; And can guarantee the position of external prestressing tendon, the active force that enough intensity is arranged and can transmit reliably the steel bundle.
If feature of the present invention also is to adopt the steel concrete steering structure, steering block fluid concrete together with junction, girder bottom flange forms integral body.Like this, be equivalent to T at the diaphragm place and become case, it has well utilized the bending resistance of case beam, torsional rigidity and globality greatly to be better than the characteristics of T beam.Simultaneously, can effectively strengthen the bridge lateral globality.Experimental study and engineering practice show, for railroad bridge, derail is directly relevant to lateral rigidity of bridge, therefore necessary assurance Lateral Stiffness of Railway Bridge.
Feature of the present invention also be steel concrete steering structure plain bars by the ring muscle that turns to pipeline, remain silent stirrup and forming to reinforcing bar in length and breadth of arranging near concrete surface.Wherein, the ring muscle is to surround the single reinforcing bar that turns to pipeline, suppose that pulling force all bears by encircling muscle, can calculate very easily and surround the single ring concrete steel muscle area that turns to pipeline.Be distributing bar to reinforcing bar in length and breadth, be evenly arranged at the steering structure concrete surface by certain reinforcement ratio.The stirrup of remaining silent is to surround all stirrups of remaining silent that turn to pipeline, also belongs to distributing bar, and generally its area of reinforcement equals to encircle the area of reinforcement of muscle.
If feature of the present invention also is to adopt steel work as steering structure, the present invention develops a kind of new steel structure steering block, i iron, horizontal coupled system, sway bracing, U-shaped hoop, consists of.
Feature of the present invention also is in the steel work steering block, and according to the longitudinal length of steel work steering block, interval 50cm arranges an i beam; I beam should adopt the i iron that meets national current standard " hot-rolled steel section " GB/T706-2008 regulation, and highly is not less than 250mm, and web thickness is not less than 10mm.
Feature of the present invention also is in the steel work steering block, along i iron longitudinal separation 1-1.5m, the web stiffening rib is set one, and the angle steel cross weld forms sway bracing on the web stiffening rib.Angle steel should adopt the angle steel that meets national current standard " hot-rolled steel section " GB/T706-2008 regulation, and the limit thickness of angle steel should not be less than 10mm; Angle steel and web stiffening rib are taked three weld all around connected modes; At the i iron roof and floor, horizontal coupled system is set along i iron longitudinal separation 1-1.5m.
Feature of the present invention also is in the steel work steering block, at the U-shaped hoop of the bottom welding of i beam.U-shaped hoop is formed by Plate Welding, turns to pipeline to pass U-shaped hoop and arranges, so just fixing prestressed cable.
Feature of the present invention also is that external prestressing tendon should adopt plant-manufactured finished product rope, and the finished product rope should adopt steel strand rope or the non-bending steel cable rope of hot extrude high density polyethylene (HDPE) oversheath, steering gear, ground tackle and should be supporting with it.
Feature of the present invention also is that steering gear adopts the cluster type steering gear, is comprised of inner tube and outer steel pipe.The cluster type steering gear can realize the replaceable design of whole bundle steel strand.The suffered dynamic load intensity of railroad bridge strengthens, the stand under load increase frequency, cause that load effect strengthens, the material stress width strengthens, cause shorten the application life of Existing Railway Bridges and roadbed and track, the safety stock of the aspects such as the intensity of structure, rigidity, stability descends, the probability that various diseases occur strengthens, the harmfulness aggravation, durability and fatigability outstanding problem.External prestressing system can detect at any time, the stress of adjustment rope, checks the corrosion condition of rope, can also carry out the steel strand replacing where necessary, has effectively solved durability and the fatigability problem of railroad bridge.
Feature of the present invention also is that reinforced concrete used is self-compacting concrete.The self-compacting concrete mixing adopts Of Concrete Mixing Station to be stirred.After the self-compacting concrete mixing completes, should be detected, the slump should be at 240mm~270mm; The slump divergence is at 600mm~700mm; The poor △ h of U-shaped instrument test height is less than 30mm; The V funnel is by the time at 4s~25s, and coarse aggregate size is 5mm~20mm, and elongated particles is less than 10%, and the fineness modulus of fines is greater than 2.3.Self-compacting concrete has been broken through the limitation of traditional vibrated concrete on molding mode, rely on self gravitation (or only needing the external force slight vibration) just can freely trickle fully, pass through reinforcing bar gap-fill template every nook and cranny, be met the intensity of requirement and good endurance quality after sclerosis.Self-compacting concrete not only from the performance guarantee of material the effect of reinforcing, also from construction technology, guaranteed consolidation effect.
Feature of the present invention also is that the bar planting spacing in 2. is that 25cm~40cm is in length and breadth to equidistant layout in step.
Feature of the present invention also is to install at reinforced concrete mid-height place, junction, concrete beam top flange steel mesh reinforcement.Diameter should adopt 12mm, arranges that distance is preferably half of bar planting distance, according to 12.5cm~20cm in length and breadth to equidistant layout.Junction, concrete beam top flange concrete height is generally 15cm~25cm, if be greater than 25cm, need arrange two-layer steel mesh reinforcement.
A kind of bridge construction self-balancing external prestressing strengthening method of the present invention, is characterized in that the method according to this invention, and relative operation comprises following key step:
Steps A: junction, concrete beam top flange interface processing
In described steps A, comprise the following steps:
(1) rendering layer of junction, top flange and decorative layer are removed, until expose concrete surface;
(2), if there are the initial imperfections such as cavity in the concrete of junction, top flange, need remove to closely knit place its rejected region;
(3) by the concrete dabbing, and the dabbing degree of depth is not less than 6mm, scum silica frost, dust that then the water cleaning concrete shows;
(4), if when the reinforcing bar at structural strengthening position has corrosion phenomena, need show rust cleaning to reinforcing bar; When the ratio of corrosion of steel bar area and former section area surpasses 1/12 in structure, need recruit reinforcing bar.
Step B: concrete beam top flange junction bar planting
Its key points for operation:
(1) while adopting embedding re-bar technique, the strength grade of concrete of bridge main member must not be lower than C25, and other concrete members strength grade must not be lower than C20.
(2) the bridge force-bearing bar planting sticks with glue agent and should adopt A level glue; Can adopt B level glue during only by structure requirement bar planting.
(3) bar planting spacing should be according to 25cm~40cm in length and breadth to equidistant layout.
Step C: junction, concrete beam top flange reinforcing bar is installed
Steel mesh reinforcement is installed at concrete mid-height place, junction, concrete beam top flange.Diameter should adopt 12mm, arranges that distance is preferably half of bar planting distance, according to 12.5cm~20cm in length and breadth to equidistant layout.Junction, concrete beam top flange concrete height is generally 15cm~25cm, if be greater than 25cm, need arrange two-layer steel mesh reinforcement.
Step D: the steering block reinforcing bar is installed at the bottom of beam and is turned to pipeline
In described step D, comprise the following steps:
(1) the external prestressing tendon steering block should be arranged on separate type girder diaphragm place, and diaphragm and steering block are jointly stressed, the active force that enough intensity can be arranged and can transmit reliably the steel bundle.Turn to pipeline should be as far as possible it to be arranged near web, because stressed comparatively favourable to the separate type kingpost baseplate of this layout, and be conducive to prestressed transmission.
(2) by bottom, former concrete beam diaphragm bottom flange concrete dabbing, and the dabbing degree of depth is not less than 6mm, scum silica frost, dust that then the water cleaning concrete shows.
(3), in the bar planting of dabbing concrete surface, spacing should be according to 25cm~40cm in length and breadth to equidistant layout.
(4) arrange the ring muscle, remain silent stirrup and near concrete surface, arrange in length and breadth to reinforcing bar.Wherein, the ring muscle is to surround the single reinforcing bar that turns to pipeline, can try to achieve by simplifying computational methods.Suppose pulling force all by the ring muscle bear, can calculate very easily and surround the single ring concrete steel muscle area that turns to pipeline.Be distributing bar to reinforcing bar in length and breadth, be evenly arranged at the steering structure concrete surface by certain reinforcement ratio.The stirrup of remaining silent is to surround all stirrups of remaining silent that turn to pipeline, also belongs to distributing bar, and generally its area of reinforcement equals to encircle the area of reinforcement of muscle.
(5) steering gear is arranged on former concrete beam bottom, adopts the cluster type steering gear, inner tube and outer steel pipe, consists of.The cluster type steering gear can realize the replaceable design of whole bundle steel strand.
The external prestressing tendon steering block also can not adopt common reinforced concrete structure, and adopts steel work.The present invention develops a kind of new steel structure steering block, i iron, horizontal coupled system, sway bracing, U-shaped hoop, consists of.Its construction key step is:
(1) according to the longitudinal length of steering block, interval 50cm arranges an i beam.
(2) i beam should adopt the i iron that meets national current standard " hot-rolled steel section " GB/T706-2008 regulation, and highly is not less than 250mm, and web thickness is not less than 10mm;
(3) along i iron longitudinal separation 1-1.5m, the web stiffening rib is set one, the angle steel cross weld forms sway bracing on the web stiffening rib.Angle steel should adopt the angle steel that meets national current standard " hot-rolled steel section " GB/T706-2008 regulation, and the limit thickness of angle steel should not be less than 10mm; Angle steel and web stiffening rib are taked three weld all around connected modes.
(4) at the i iron roof and floor, horizontal coupled system is set along i iron longitudinal separation 1-1.5m.
(5) at the U-shaped hoop of the bottom welding of i beam.U-shaped hoop is formed by Plate Welding, turns to pipeline to pass U-shaped hoop and arranges, so just fixing prestressed cable.
Step e: apart from the symmetrical diaphragm that increases in beam-ends 2-3m place, ground tackle is installed and is comprised the following steps in described step e:
(1) will increase the connecting portion concrete dabbing of diaphragm and former concrete beam newly, and the dabbing degree of depth is not less than 6mm, scum silica frost, dust that then the water cleaning concrete shows.
(2), in the bar planting of dabbing concrete surface, spacing should be according to 25cm~40cm in length and breadth to equidistant layout.
(3) arrange the diaphragm reinforcing bar, notice that the diaphragm reinforcing bar will be connected with bar planting, strengthens overall work.
(4) external prestressing tendon anchorage installation location.The newly-increased diaphragm of the present invention both can be strengthened integral working, can be used as again the anchoring crossbeam, and easy construction, can avoid original girder beam-ends prestress anchoraging complexity, there is no the problem of construction space.The ground tackle material should meet " ground tackle, fixture and connector for prestressed strand " (GB/T14370-2007) requirement of standard, and the external pre-stress bundle ground tackle adopts the strand tapered anchorage of corresponding standard, and ground tackle should meet the requirement that integral body is changed bundle and adjusted stretching force.Ground tackle steel pipe used all adopts the seamless steel pipe that meets the GB8163-87 regulation, and other performance of ground tackle should meet the requirement of GB/T14370-2000 standard.
Step F: cast junction, girder top flange, steering block and newly-increased diaphragm concrete concrete adopt self-compacting concrete, comprise self-compacting concrete mixing, cast, maintenance.
The self-compacting concrete mixing:
Adopt Of Concrete Mixing Station to be stirred.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 gratings are qualified, bulk density 1576kg/m 3, apparent density 2610kg/m 3;
(4) stone: rubble, 5-20mm continuous grading is qualified, and elongated particles 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%.
After concrete mixing completes, should carry out slump consistancy test, the test of L-type Flow Meter, the test of U-shaped instrument, V funnel testing, its testing result should meet following standard: the slump should be controlled at 240mm~270mm; The slump divergence should be controlled at 600mm~700mm; The poor △ h of U-shaped instrument test height should be less than 30mm; The V funnel should be controlled at 4s~25s by the time.
The self-compacting concrete cast:
(1) half an hour before the cast,, water is moistening former concrete beam and template fully;
(2) the self-compacting concrete cast can adopt mechanical continuous pouring and artificial continuous pouring, the continuous pouring of recommendation machinery.Guarantee that continuous several plug hole pours into a mould as far as possible simultaneously, can suitably plug and pound with long pricker in case of necessity with wooden mallet to steel plate percussion vibration a little during cast, guarantee the closely knit of fluid concrete;
(3) should note each position distortion of structure while pouring into a mould, answer strenthening member of continuous pouring complete, and the middle ware break time can not surpass the concrete initial set time;
The self-compacting concrete maintenance:
After pouring concrete completes, should execute in time water curing, guarantee 7~14 day curing time: should execute the water curing least four times first 7 day every day: morning working, and before having a meal noon, before having supper at dusk, between evening 11~12.Latter 7 days, execute water curing every day early, middle and late three times.
Step G: installation, stretch-draw anchor external prestressing tendon
The material of external prestressing tendon should meet " steel strand for prestressed concrete " (GB/T5224), " un-bonded prestressed steel strand " (JG161), " building cable high-density polyethylene plastics " (CJ/T3078), " Standards of Seamless Steel Structural Tubes " (GB/T8162), " cable stayed bridge hot extruded polyethylene high strength steel cable technical condition " (GB/T18365), " unbonded prestressing tendon special anti-corrosion lubricating grease " (JG3007-93) and " semi-refined paraffin wax " requirement of standard such as (GB254).External prestressing tendon should adopt plant-manufactured finished product rope, and the finished product rope should adopt steel strand rope or the non-bending steel cable rope of hot extrude high density polyethylene (HDPE) (be called for short HDPE) oversheath, and should be supporting with steering gear, ground tackle.
Technique scheme of the present invention is compared traditional reinforcement means and is had the following advantages:
(1) a kind of bridge construction self-balancing external prestressing strengthening method provided by the invention, external prestressing tendon is arranged in former girder bottom by steering block, at junction, former girder top flange cast self-compacting concrete, both can give full play to the reinforcement effect of external prestressing tendon, can allow again junction, top flange concrete directly bear pre-applied force, thereby, when promoting former bridge bearing ability, do not increase former bridge burden, i.e. self equilibrium systems.
(2) the present invention is increasing diaphragm newly near the beam-ends place.Not only can improve the lateral stiffness of bridge construction, can also will increase the anchoring crossbeam of diaphragm as external prestressing tendon newly.Girder beam-ends prestress pipe complicated layout, do not have the anchoring space of external prestressing tendon; Two bridge end gaps are narrow, also there is no the stretch-draw space, even there is construction space, difficulty of construction is also large especially.Adopt newly-increased diaphragm as anchoring crossbeam fixing body External prestressed ground tackle and stretch-draw cable wire easily, also can meet the requirement of cable wire in lateral arrangement.
(3) the present invention is arranged on the steering structure of external prestressing tendon at the diaphragm place of original separate type girder, both can adopt reinforced concrete structure, also can adopt steel work.At the bottom of transfer not only can be arranged on beam, and, for the girder of separate type, also can be arranged on the middle interconnecting piece position of two separate type girders.The linear layout of external prestressing tendon facade can arrange the horizontal linear section, also can arrange, and like this, just can meet different linear arrangement requirement, applied widely.
(4) if the present invention adopts the steering structure of steel concrete, steering block fluid concrete together with junction, girder bottom flange forms integral body.Like this, be equivalent to T at the diaphragm place and become case, can effectively strengthen the bridge lateral globality.
(5) if the present invention adopts the steering structure of steel work, a kind of new steel structure steering block according to the invention exploitation, be comprised of i iron, horizontal coupled system, sway bracing, U-shaped hoop, and easy construction is quick, economic and practical.
(6) the outstanding characteristics for the railroad bridge fatigue problem, prestressing with bond can't detect and change rope after grouting finishes, external prestressing system can detect at any time, the stress of adjustment rope, checks the corrosion condition of rope, can also be keeped in repair where necessary, change rope.
(7) adopt self-balancing external prestressing strengthening technology of the present invention, little on the impact of structure headway, do not affect vehicle pass-through.Therefore technical method of the present invention is particularly suitable for railroad bridge, overpass bridge and bridge crossing, and to headway strict structure.
(8) due to the present invention utilized self-compacting concrete in casting process without the moulding of vibrating, therefore the invention solves arrangement of reinforcement intensive, complex structure, template and former member narrow space etc. block because of aggregate the problems such as cavity that cause, and reduced the conventional concrete construction and shaken because of leakage, the pitted skin of hierarchical cellular up and down that crossing shakes causes, concrete quality and endurance quality have been improved, thereby greatly simplified reinforcing construction process, the position that ordinary concrete can't be constructed may become, be specially adapted to some complexity, the ruggedized construction member of the opposite sex, greatly expanded the scope of application.
(9) because the present invention has utilized self-compacting concrete, significantly reduced the noise pollution in traditional vibrated concrete construction, significantly alleviated workman's labour intensity.Because the preparation self-compacting concrete need to utilize the industrial solid castoffs such as flyash, granulated blast-furnace slag, silicon ash in a large number, be conducive to the comprehensive utilization of resource and the protection of ecological environment simultaneously.
In sum, compared with prior art, self-balancing external prestressing strengthening technology of the present invention in conjunction with the self-balancing principle, utilize self-compacting concrete, external prestressing advantage separately, can effectively improve existing bridge stiffness and bearing capacity, simultaneously do not increase former axle load to carry.For the outstanding characteristics of heavy haul railway bridge fatigue problem, external prestressing system can detect at any time, the stress of adjustment rope, checks the corrosion condition of rope, can also be keeped in repair where necessary, change rope.Self-compacting concrete has solved that arrangement of reinforcement is intensive, complex structure, template and former member narrow space etc. are because aggregate blocks the problems such as cavity that cause, and effectively guarantees the fluid concrete compactness, has improved consolidation effect.Can be widely used in heavy haul railway bridge, concrete box girder, the reinforcing of T beam, overall cost is low, economic, safety, applicable, and workmanship is easy to assurance, and application prospect is extensive.
The accompanying drawing explanation
Accompanying drawing is used to provide a further understanding of the present invention, and forms the part of manual, together with embodiments of the present invention for explaining the present invention.Wherein
Fig. 1 is heavy haul railway prestressed concrete simple T girder bridge elevation;
Fig. 2 is heavy haul railway prestressed concrete simple T girder bridge standard section figure;
Fig. 3 is heavy haul railway prestressed concrete simple T girder bridge diaphragm profile;
Fig. 4 is the junction bar planting of girder top board, fluid concrete schematic diagram;
Fig. 5 a is that external prestressing tendon steel concrete transfer is installed cast schematic diagram one;
Fig. 5 b is that external prestressing tendon steel concrete transfer is installed cast schematic diagram two;
Fig. 6 a is external prestressing tendon steel work transfer scheme of installation one;
Fig. 6 b is external prestressing tendon steel work transfer scheme of installation two;
Fig. 7 is steel work transfer constructional drawing;
Fig. 8 a is that after reinforcing, the structure facade is arranged schematic diagram one;
Fig. 8 b is that after reinforcing, the structure facade is arranged schematic diagram two;
Fig. 9 is intrafascicular steering gear scheme of installation of steel;
Figure 10 is steering gear structure drawing;
In figure, Reference numeral is expressed as: 1-concrete T-shaped beam top board; 2-concrete T-shaped beam web; 3-concrete T-shaped beam base plate; 4-diaphragm; 5-top board junction; 6-steering block; 7-external prestressing tendon; 8-newly-increased diaphragm; The steering gear of 9-external prestressing tendon; 10-external prestressing cable anchorage; 11-HDPE inner tube; 12-outer steel pipe; 13-top flange reinforced concrete; 14-i beam, 15-horizontal coupled system, 16-sway bracing, 17-U-shaped hoop; 18-web stiffening rib; 19-three weld all arounds.
The specific embodiment
Below in conjunction with accompanying drawing, the preferred embodiments of the present invention are described, wherein in figure, Reference numeral is expressed as: 1-concrete T-shaped beam top board; 2-concrete T-shaped beam web; 3-concrete T-shaped beam base plate; 4-diaphragm; Junction, 5-top flange; 6-steering block; 7-external prestressing tendon; 8-newly-increased diaphragm; The steering gear of 9-external prestressing tendon; 10-external prestressing cable anchorage; 11-HDPE inner tube; 12-outer steel pipe; 13-top flange reinforced concrete; 14-i beam, 15-horizontal coupled system, 16-sway bracing, 17-U-shaped hoop; 18-web stiffening rib; 19-three weld all arounds.
Solution of the present invention is on the basis of existing technology, a kind of bridge construction self-balancing external prestressing strengthening method is provided, the concrete T-shaped beam top board of two concrete T-shaped beams forms the girder top flange, the concrete T-shaped beam base plate of two concrete T-shaped beams forms bottom flange, it is characterized in that comprising the following 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, beam and is turned to pipeline; E, the symmetrical diaphragm that increases of close beam-ends, install ground tackle; F, cast junction, girder top flange, newly-increased diaphragm concrete; G, installation, stretch-draw anchor external prestressing tendon, obtain the structure of self-balancing external prestressing strengthening.
Feature of the present invention also is by bar planting bottom the girder top flange, junction, two girder top flanges cast self-compacting concrete, external prestressing tendon is arranged in the girder bottom, junction, top flange concrete and external prestressing tendon form subtriangular self equilibrium systems, and described girder comprises T beam, concrete box girder, hollow slab beam, normal reinforced concrete beam or the prestressed concrete beam existed.
Feature of the present invention also is the newly-increased diaphragm near beam-ends 2-3m place.
Feature of the present invention also is the anchoring crossbeam of newly-increased diaphragm as external prestressing tendon, and the ground tackle of external prestressing tendon is arranged in newly-increased diaphragm.
Feature of the present invention also is that the steering structure of external prestressing tendon is arranged on the diaphragm place of original separate type girder.
Feature of the present invention also is that the transfer of external prestressing tendon adopts reinforced concrete structure or adopts steel work, at the bottom of transfer is arranged on beam, perhaps for the erection of main beam of separate type in the middle interconnecting piece position of two separate type girders, or the linear layout of external prestressing tendon facade arranges the horizontal linear section.
If feature of the present invention also is the external prestressing tendon transfer and adopts reinforced concrete structure, comprise at step D the construction sequence that the steering block plain bars is installed, comprise the concrete construction sequence of cast steering block in step F.
Feature of the present invention also is that steering block fluid concrete together with junction, girder diaphragm bottom flange forms integral body.
Feature of the present invention also be steel concrete steering structure plain bars by the ring muscle that turns to pipeline, remain silent stirrup and forming to reinforcing bar in length and breadth of arranging near concrete surface, the ring muscle is to surround the single reinforcing bar that turns to pipeline, to reinforcing bar, be distributing bar in length and breadth, by certain reinforcement ratio, at the steering structure concrete surface, be evenly arranged, the stirrup of remaining silent is to surround all stirrups of remaining silent that turn to pipeline, belong to distributing bar, its area of reinforcement equals to encircle the area of reinforcement of muscle.
If feature of the present invention also is external prestressing tendon transfer employing steel work, the steel work transfer is comprised of i beam, horizontal coupled system, sway bracing and U-shaped hoop.
Feature of the present invention also is the longitudinal length according to the steel work transfer, interval 50cm arranges an i beam, and i beam adopts the i iron that meets national current standard " hot-rolled steel section " GB/T706-2008 regulation, and highly be not less than 250mm, web thickness is not less than 10mm.
Feature of the present invention also is, along i beam longitudinal separation 1-1.5m, the web stiffening rib is set one, the angle steel cross weld forms sway bracing on the web stiffening rib, angle steel should adopt the angle steel that meets national current standard " hot-rolled steel section " GB/T706-2008 regulation, and the limit thickness of angle steel should not be less than 10mm, angle steel and web stiffening rib are taked three weld all around connected modes, along i beam longitudinal separation 1-1.5m, at the i beam roof and floor, horizontal coupled system are set.
Feature of the present invention also is that U-shaped hoop is formed by Plate Welding at the U-shaped hoop of the bottom welding of i beam, turns to pipeline to pass U-shaped hoop and arranges, thus fixing external prestressing tendon.
Feature of the present invention also is that external prestressing tendon adopts plant-manufactured finished product rope, the finished product rope adopts 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 steering gear adopts the cluster type steering gear, inner tube and outer steel pipe, consists of.
Feature of the present invention also is that described concrete is self-compacting concrete, and the self-compacting concrete mixing adopts Of Concrete Mixing Station to be stirred, and its raw material are: cement: adopt common 42.5 portland cements; Flyash: I level flyash; Sand: river sand, medium sand, fineness modulus 2.58 ,Ⅱ district gratings are qualified, bulk density 1576kg/m 3, apparent density 2610kg/m 3; Stone: rubble, 5-20mm continuous grading is qualified, and elongated particles is 9.2%, crush index 3.4, bulk density 1470kg/m 3, apparent density 2700kg/m 3; Water reducing agent: high efficiency water reducing agent, water-reducing rate is greater than 25%.
Feature of the present invention also is to be detected after the self-compacting concrete mixing completes, and the slump should be at 240mm~270mm; The slump divergence is at 600mm~700mm; The poor △ h of U-shaped instrument test height is less than 30mm; The V funnel is by the time at 4s~25s, and coarse aggregate size is 5mm~20mm, and elongated particles is less than 10%, and the fineness modulus of fines is greater than 2.3.
Feature of the present invention also is that the bar planting spacing in step B is that 25cm~40cm is in length and breadth to equidistant layout.
Feature of the present invention also is to install at reinforced concrete mid-height place, junction, concrete beam top flange steel mesh reinforcement, diameter adopts 12mm, arrange that distance is preferably half of bar planting distance, according to 12.5cm~20cm in length and breadth to equidistant layout, junction, concrete beam top flange concrete height is generally 15cm~25cm, if be greater than 25cm, need arrange two-layer steel mesh reinforcement.
The specific embodiment is heavy haul railway prestressing force simple T beam bridge, and self-balance prestress reinforcing technique according to the present invention comprises the following steps:
Steps A: junction, concrete T-shaped beam top flange 5 interface processing
Fig. 1 is heavy haul railway prestressed concrete simple T girder bridge elevation; Have five diaphragms 4 between the concrete T-shaped beam top board 1 of prestressed concrete simple T girder bridge as shown in Figure 1 and concrete T-shaped beam base plate 3, diaphragm 4 arranges perpendicular to concrete T-shaped beam web 2, and prestressed concrete simple T girder bridge as shown in Figure 1 includes common section and contains two kinds of different sections of diaphragm section.
Fig. 2 is heavy haul railway prestressed concrete simple T girder bridge standard section figure; As shown in Figure 2, the standard section of the present embodiment comprises concrete T-shaped beam top board 1, concrete T-shaped beam web 2 and concrete T-shaped beam base plate 3.
Fig. 3 is heavy haul railway prestressed concrete simple T girder bridge diaphragm profile; As shown in Figure 3, by perpendicular to two concrete T-shaped beams willfully the annular diaphragm 4 on face two concrete T-shaped beams are coupled to integral body, annular diaphragm 4 is simultaneously perpendicular to concrete T-shaped beam top board 1, concrete T-shaped beam web 2 and the concrete T-shaped beam base plate 3 of two concrete T-shaped beams.
In described steps A, comprise the following steps:
Fig. 4 is the junction bar planting of girder top board, fluid concrete schematic diagram; As shown in Figure 4,
Between two concrete T-shaped beam webs 2 of (1) two concrete T-shaped beam, concrete T-shaped beam top board 1 bottom of section is junction, T beam top flange 5, the rendering layer of junction, top flange 5 and decorative layer is removed, until expose concrete surface;
(2), if there are the initial imperfections such as cavity in the concrete of junction, top flange 5, need remove to closely knit place its rejected region;
(3) by junction, top flange 5 bottom surface dabbings, and the dabbing degree of depth is not less than 6mm, then the scum silica frost on water cleaning concrete surface, dust;
(4), if when the reinforcing bar at structural strengthening position has corrosion phenomena, need show rust cleaning to reinforcing bar; When the ratio of corrosion of steel bar area and former section area surpasses 1/12 in structure, need recruit reinforcing bar.
Step B: junction, concrete T-shaped beam top flange 5 concrete surface bar plantings
Its key points for operation:
(1) while adopting embedding re-bar technique, the strength grade of concrete of bridge main member must not be lower than C25, and other concrete members strength grade must not be lower than C20.
(2) the bridge force-bearing bar planting sticks with glue agent and should adopt A level glue; Can adopt B level glue during only by structure requirement bar planting.
(3) bar planting spacing should be according to 25cm~40cm in length and breadth to equidistant layout.
Step C: the plain bars that junction, concrete T-shaped beam top flange 5 is installed
Fig. 4 is the junction bar planting of girder top board, fluid concrete schematic diagram; As shown in Figure 4, at concrete T-shaped beam top flange reinforced concrete 13 mid-height places, steel mesh reinforcement is installed.Diameter should adopt 12mm, arranges that distance is preferably half of bar planting distance, according to 12.5cm~20cm in length and breadth to equidistant layout.The height of T beam top flange reinforced concrete 13 is generally 15cm~25cm, if be greater than 25cm, need arrange two-layer steel mesh reinforcement.
Reinforcing bar and the external prestressing tendon steering gear 9 of steering block 6 are installed at the bottom of step D:T beam beam
According to the present invention, steering block 6 both can adopt reinforced concrete structure, can adopt steel work again.Fig. 5 a is that external prestressing tendon steel concrete transfer is installed cast schematic diagram one; Fig. 5 b is that external prestressing tendon steel concrete transfer is installed cast schematic diagram two; As shown in Fig. 5 a and Fig. 5 b,
In described step D, comprise the following steps:
(1) external prestressing tendon steering block 6 is arranged on separate type girder diaphragm 4 places, and diaphragm 4 and steering block 6 are jointly stressed, the active force that enough intensity can be arranged and can transmit reliably the steel bundle.
(2) by former concrete beam diaphragm 4 bottom, bottom flange concrete dabbings, and the dabbing degree of depth is not less than 6mm, scum silica frost, dust that then the water cleaning concrete shows.
(3), in the bar planting of dabbing concrete surface, spacing should be according to 25cm~40cm in length and breadth to equidistant layout.
(4) arrange the ring muscle, remain silent stirrup and near concrete surface, arrange in length and breadth to reinforcing bar.
(5) external prestressing tendon steering gear 9 is arranged on former concrete beam bottom, adopts the cluster type steering gear.Fig. 7 is intrafascicular steering gear scheme of installation of steel; As shown in Figure 7, according to the linear layout of external prestressing tendon 7, pre-buried external prestressing tendon steering gear 9 in steering block 6.Fig. 9 is intrafascicular steering gear scheme of installation of steel; Figure 10 is steering gear structure drawing; As shown in figure 10, external prestressing tendon steering gear 9 is comprised of HDPE inner tube 11 and outer steel pipe 12.
(6) Fig. 5 b is that external prestressing tendon steel concrete transfer is installed cast schematic diagram one; As shown in Figure 5 b, the method according to this invention, external prestressing tendon steering block 6 also can be arranged on the middle interconnecting piece position of two separate type girders, can meet so the various linear arrangement requirement of external prestressing tendon 7.
If external prestressing tendon steering block 6 adopts steel work, develop a kind of new steel structure steering block according to the present invention, by i beam 14, horizontal coupled be 15, sway bracing 16, U-shaped hoop 17 form.Fig. 6 a is external prestressing tendon steel work transfer scheme of installation one; Fig. 6 b is external prestressing tendon steel work transfer scheme of installation two; Fig. 7 is steel work transfer constructional drawing; As shown in Fig. 6 a, Fig. 6 b, Fig. 7,
Its construction key step is:
(1) according to the longitudinal length of steering block 6, interval 50cm arranges an i beam 14.The steering block 6 of the present embodiment is comprised of two i beams 14.
(2) i beam 14 should adopt the i iron that meets national current standard " hot-rolled steel section " GB/T706-2008 regulation, and highly is not less than 250mm, and web thickness is not less than 10mm.The i beam 14 that the present embodiment is selected is highly 300mm, and web thickness is 13mm.
(3) Fig. 7 is steel work transfer constructional drawing; As shown in Figure 7, along i beam, 14 longitudinal separation 1-1.5m arrange web stiffening rib 18 one, and the angle steel cross weld forms sway bracing 16 on web stiffening rib 18.Angle steel should adopt the angle steel that meets national current standard " hot-rolled steel section " GB/T706-2008 regulation, and the limit thickness of angle steel should not be less than 10mm; Angle steel and web stiffening rib 18 are taked three weld all around connected modes.The transverse width of the steering block 6 of the present embodiment is 2880mm, along i beam, 14 longitudinal separation 1m arrange web stiffening rib 18, and the thickness of web stiffening rib 18 is 10mm, and the limit thickness of angle steel is 10mm, as shown in Figure 7, the welding manner of angle steel and web stiffening rib 18 is three weld all arounds 19.
(4) Fig. 7 is steel work transfer constructional drawing; As shown in Figure 7, at i beam 14 roof and floors, horizontal coupled being set along i beam 14 longitudinal separation 1-1.5m is 15.It is 15 that the present embodiment forms horizontal coupled according to the thick steel plate of longitudinal separation 1m welding 10mm.
(5) at the U-shaped hoop 17 of the bottom welding of i beam 14.U-shaped hoop 17 is formed by Plate Welding, turns to pipeline to pass U-shaped hoop 17 and arranges, so just fixing external prestressing tendon 7.
(6) the same with the steel concrete steering structure, Fig. 6 b is external prestressing tendon steel work transfer scheme of installation two; As shown in Figure 6 b, the method according to this invention, the external prestressing tendon steering block 6 of steel work also can be arranged on the middle interconnecting piece position of two separate type girders, can meet so the various linear arrangement requirement of external prestressing tendon 7.
Step e: apart from the newly-increased diaphragm 8 of beam-ends 2m place cast, fixing body External prestressed cable anchorage 10
In described step e, comprise the following steps:
(1) will increase the connecting portion concrete dabbing of diaphragm 8 and former concrete beam newly, and the dabbing degree of depth is not less than 6mm, scum silica frost, dust that then the water cleaning concrete shows.
(2), in the bar planting of dabbing concrete surface, spacing should be according to 25cm~40cm in length and breadth to equidistant layout.
(3) arrange the reinforcing bar of newly-increased diaphragm 8, notice that the reinforcing bar of newly-increased diaphragm 8 will be connected with bar planting, strengthen overall work.
(4) external prestressing cable anchorage 10 is installed location.Fig. 8 a is that after reinforcing, the structure facade is arranged schematic diagram one; Fig. 8 b is that after reinforcing, the structure facade is arranged schematic diagram two; As shown in Fig. 8 a and 8b, external prestressing cable anchorage 10 is arranged in newly-increased diaphragm 8.The newly-increased diaphragm 8 arranged according to invention both can be strengthened integral working, can be used as again the anchoring crossbeam, and easy construction, can avoid original girder beam-ends prestress anchoraging complexity, there is no the problem of construction space.
Step F: concrete Fig. 8 a of cast junction, T beam top flange 5, steering block 6 and newly-increased diaphragm 8 is that after reinforcing, the structure facade is arranged schematic diagram one; Fig. 8 b is that after reinforcing, structure facade layout is shown
Intention two; As shown in Fig. 8 a and 8b, newly-increased diaphragm 8 of the present invention will be as the anchoring crossbeam.Concrete
Adopt self-compacting concrete, comprise self-compacting concrete mixing, cast, maintenance.
The self-compacting concrete mixing:
Adopt Of Concrete Mixing Station to be stirred.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 gratings are qualified, bulk density 1576kg/m 3, apparent density 2610kg/m 3;
(4) stone: rubble, 5-20mm continuous grading is qualified, and elongated particles 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%.
After concrete mixing completes, should carry out slump consistancy test, the test of L-type Flow Meter, the test of U-shaped instrument, V funnel testing, its testing result should meet following standard: the slump should be controlled at 240mm~270mm; The slump divergence should be controlled at 600mm~700mm; The poor △ h of U-shaped instrument test height should be less than 30mm; The V funnel should be controlled at 4s~25s by the time.
The self-compacting concrete cast:
(1) half an hour before the cast,, water is moistening former concrete beam and template fully;
(2) the self-compacting concrete cast can adopt mechanical continuous pouring and artificial continuous pouring, the continuous pouring of recommendation machinery.Guarantee that continuous several plug hole pours into a mould as far as possible simultaneously, can suitably plug and pound with long pricker in case of necessity with wooden mallet to steel plate percussion vibration a little during cast, guarantee the closely knit of fluid concrete;
(3) should note each position distortion of structure while pouring into a mould, answer strenthening member of continuous pouring complete, and the middle ware break time can not surpass the concrete initial set time;
The self-compacting concrete maintenance:
After pouring concrete completes, should execute in time water curing, guarantee 7~14 day curing time: should execute the water curing least four times first 7 day every day: morning working, and before having a meal noon, before having supper at dusk, between evening 11~12.Latter 7 days, execute water curing every day early, middle and late three times.
Step G: installation, stretch-draw anchor external prestressing tendon 7
Fig. 8 a is that after reinforcing, the structure facade is arranged schematic diagram one; Fig. 8 b is that after reinforcing, the structure facade is arranged schematic diagram two; As shown in Fig. 8 a and 8b, according to stressed needs, the layout of horizontal linear segment body External prestressed rope 7 is arranged, as shown in Figure 8 a in the middle of can adopting; Also can adopt triangular arrangement, as shown in Figure 8 b.At the bottom of the steering block of external prestressing tendon 7 can be arranged on beam, as shown in Fig. 5 a and 6a; Also can be arranged on the middle interconnecting piece position of two separate type girders, as shown in Fig. 5 b and 6b.Like this, according to external prestressing tendon 7 method for arranging provided by the invention, linear, the lateral attitude of layout external prestressing tendon 7 that can be convenient, flexible, steel bundle bundle number.
Stretching force in the present invention is directly born by the concrete of junction, top flange 5, form self equilibrium systems between prestressed cable 7 and junction, top flange 5 concrete in vitro, can give full play to the reinforcement effect of external prestressing tendon 7, not increase again the burden of existing concrete T-shaped beam.
The material of external prestressing tendon 7 should meet " steel strand for prestressed concrete " (GB/T5224), " un-bonded prestressed steel strand " (JG161), " building cable high-density polyethylene plastics " (CJ/T3078), " Standards of Seamless Steel Structural Tubes " (GB/T8162), " cable stayed bridge hot extruded polyethylene high strength steel cable technical condition " (GB/T18365), " unbonded prestressing tendon special anti-corrosion lubricating grease " (JG3007-93) and " semi-refined paraffin wax " requirement of standard such as (GB254).The external prestressing tendon 7 of the present embodiment adopts plant-manufactured finished product rope, and supporting with external prestressing tendon steering gear 9, external prestressing cable anchorage 10.
Easily understand, although above be the explanation of the present invention being carried out in conjunction with the T beam bridge, yet the present invention can similarly be applied to other form of structure, as the little case beam in concrete box girder, hollow slab beam, highway etc.
Finally it should be noted that: above concrete real-time mode is described is only the preferred embodiments of the invention.Although with reference to foregoing embodiments, the present invention is had been described in detail, for a person skilled in the art, the technical scheme that still can put down in writing previous embodiment is modified, or part technical characterictic wherein is equal to replacement.Within the spirit and principles in the present invention all, any modification of doing, be equal to replacement, improvement etc., within all should being included in protection scope of the present invention.

Claims (10)

1. a bridge construction self-balancing external prestressing strengthening method is characterized in that comprising the following 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, beam and is turned to pipeline;
E, the symmetrical diaphragm that increases of close beam-ends, install ground tackle;
F, cast junction, girder top flange, newly-increased diaphragm concrete;
G, installation, stretch-draw anchor external prestressing 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 by bar planting bottom the girder top flange, junction, two girder top flanges cast self-compacting concrete, external prestressing tendon is arranged in the girder bottom, junction, top flange concrete and external prestressing tendon form subtriangular self equilibrium systems, and described girder comprises T beam, concrete box girder, hollow slab beam, normal reinforced concrete beam or the prestressed concrete beam 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 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 tendon 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 tendon adopts reinforced concrete structure or adopts steel work, at the bottom of transfer is arranged on beam, perhaps for the erection of main beam of separate type in the middle interconnecting piece position of two separate type girders, or the linear layout of external prestressing tendon facade arranges the horizontal linear section.
7. a kind of bridge construction self-balancing external prestressing strengthening method according to claim 1, if it is characterized in that, the external prestressing tendon transfer adopts reinforced concrete structure, comprise at step D the construction sequence that the steering block plain bars is installed, in step F, comprise the concrete construction sequence of cast steering block.
8. a kind of bridge construction self-balancing external prestressing strengthening method according to claim 7, is characterized in that steering block fluid concrete together with junction, girder diaphragm bottom flange forms 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 by the ring muscle that turns to pipeline, remain silent stirrup and forming to reinforcing bar in length and breadth of arranging near concrete surface, the ring muscle is to surround the single reinforcing bar that turns to pipeline, to reinforcing bar, be distributing bar in length and breadth, by certain reinforcement ratio, at the steering structure concrete surface, be evenly arranged, the stirrup of remaining silent is to surround all stirrups of remaining silent that turn to pipeline, 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 claim 1 to 5, if it is characterized in that, the external prestressing tendon transfer adopts steel work, and the steel work transfer is comprised of i beam, horizontal coupled system, sway bracing and U-shaped hoop; Perhaps, according to the longitudinal length of steel work transfer, interval 50cm arranges an i beam, and i beam adopts the i iron that meets national current standard " hot-rolled steel section " GB/T706-2008 regulation, and highly is not less than 250mm, and web thickness is not less than 10mm; Perhaps along i beam longitudinal separation 1-1.5m, the web stiffening rib is set one, the angle steel cross weld forms sway bracing on the web stiffening rib, angle steel should adopt the angle steel that meets national current standard " hot-rolled steel section " GB/T706-2008 regulation, and the limit thickness of angle steel should not be less than 10mm, angle steel and web stiffening rib are taked three weld all around connected modes, along i beam longitudinal separation 1-1.5m, at the i beam roof and floor, horizontal coupled system are set; Perhaps, at the U-shaped hoop of the bottom welding of i beam, U-shaped hoop is formed by Plate Welding, and turn to pipeline to pass U-shaped hoop and arrange, thus fixing external prestressing tendon; Perhaps external prestressing tendon adopts plant-manufactured finished product rope, the finished product rope adopts 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 steering gear adopts the cluster type steering gear, inner tube and outer steel pipe, consists of; Perhaps described concrete is self-compacting concrete, and the self-compacting concrete mixing adopts Of Concrete Mixing Station to be stirred, 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 gratings are qualified, bulk density 1576kg/m 3, apparent density 2610kg/m 3; (4) stone: rubble, 5-20mm continuous grading is qualified, and elongated particles 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%; Perhaps the self-compacting concrete mixing is detected after completing, and the slump should be at 240mm~270mm; The slump divergence is at 600mm~700mm; The poor △ h of U-shaped instrument test height is less than 30mm; The V funnel is by the time at 4s~25s, and coarse aggregate size is 5mm~20mm, and elongated particles 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; Steel mesh reinforcement perhaps is installed at reinforced concrete mid-height place, junction, concrete beam top flange, diameter adopts 12mm, arrange that distance is preferably half of bar planting distance, according to 12.5cm~20cm in length and breadth to equidistant layout, junction, concrete beam top flange concrete height is generally 15cm~25cm, if be greater than 25cm, need arrange two-layer steel mesh reinforcement.
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