CN100570067C - Prestressed method of suspension bridge anchoring changeable formula and device - Google Patents

Abstract

The invention discloses a kind of prestressed method of suspension bridge anchoring changeable formula and device, its step, the one, the prerequisite that the design stage satisfies, whole bundle prestressing force satisfies the lasting situation safety conditions of main cable strand, and the satisfied wherein n ' velamen of whole bundle prestressing force is substituted transient situation safety conditions when loosening; The 2nd, the later stage is judged the condition of changing rope; The 3rd, substitute mode is the mode of substituting, and the number of share of stock that once loosens is not more than n '; The 4th, change Suo Fangfa, change the single or many modes of substituting of Suo Caiyong and carry out, the radical n ' that moves back anchor satisfy the transient situation safety conditions.Device comprises the pre-pipe laying of honeycomb fashion, presstressed reinforcing steel, anchor plate, spiral reinforcement, anticorrosion grease, hexagon steel sleeve, leakproof end plate, outsourcing hexagon steel pipe, circular steel sleeve pipe under anchor slab, intermediate plate, locking baffle plate, protective cover, the anchor.The inventive method is easy, changes convenient, safety, and is simple in structure, reliable and stable, realized that effectively whole bundle presstressed reinforcing steel can safeguard, improved the safety and the reliability of bridge.

Description

Prestressed method of suspension bridge anchoring changeable formula and device

Technical field

The present invention relates to a kind of prestressing technique field that is used for the suspension bridge anchorage, more specifically relate to the prestressed method of a kind of suspension bridge anchoring changeable formula, also relate to the prestressed device of bridge anchoring changeable formula simultaneously, keeping with the effective anchoring of main rope of suspension bridge strand, guaranteeing under the prerequisite of bridge safety, replace constituting the prestressed multiply presstressed reinforcing steel of whole bundle, thereby the prestressing without bondn of realizing bridge later stage maintainability is constructed.

Background technology

Anchorage is that suspension bridge is stressed, the key structure of carrying, and it plays a part to transmit tension of main cable to the basis.Generally be divided into gravity anchor and tunnel-type anchorage two classes from the mode of transfer force between anchorage and the foundation.Gravity anchor relies on the huge pulling force of the dead-weight balanced main push-towing rope of anchorage, and tunnel-type anchorage utilizes the acting in conjunction of anchorage and its surrounding rock body, the anchoring main push-towing rope.

The main rope of suspension bridge pulling force is huge, and anchorage is generally large volume concrete structural, under the tension of main cable effect, anchorage can produce very big tensile stress and cause concrete cracking, so need apply prestressing force to anchorage,, guarantee the safety of structure with the tensile stress that the opposing tension of main cable produces.

The modern suspension anchorage adopts prestress system more, and existing anchorage prestress system has two kinds: bonding system and no bonding system are arranged.

Anchorage bonded prestress system, to common post-stressed similar: when cast anchor body concrete, adopt steel pipe, or metal bellows, or plastic film capicitor reserves the pipeline that prestressed strand is walked in concrete, the pre-buried backing plate that can transmit immense pressure in the anchor surface concrete of front and back, after concrete reaches certain intensity, prestressed strand (presstressed reinforcing steel) is passed the pipeline of reservation, adopt fluid pressure type jack tension prestressed strand to certain tonnage, stress level, by ground tackle fluid pressure type jack tension power is changeed being added on the backing plate pre-buried in the anchor surface concrete of front and back at last, thereby the anchor body concrete has been applied precompression.By being connected of ground tackle and main push-towing rope bundle thigh, main push-towing rope power is delivered to the anchor body.Be characterized in, after prestressed stretch-draw is finished, to prestress pipe, anchor head cement injection mortar or epoxy mortar, mortar and prestressed strand form permanent adhesive, make prestressed strand and anchor body become integral body, mortar and the bonding, airtight of prestressed strand play antisepsis to prestressed strand simultaneously.

The main deficiency of the bonded prestress system of perfusion mortar is: (1) detection, difficult in maintenance is difficult to the actual corrosion situation of prestressed strand is made judgement accurately; (2) because mortar solidifies the influence of after-contraction, microcrack appears unavoidably, and anticorrosion unreliable; (3) prestressed strand and anchoring intermediate plate bond together by mortar curing, can't under the prerequisite that guarantees structural integrity, change and safeguard, and be the prestress system of " disposable ".

At bonded prestress mode anti-corrosive properties, the shortcoming that detection property is not good, people have proposed not have bonding prestressing force mode, conventional no bonding prestressed 26S Proteasome Structure and Function main points are: when cast anchor body concrete the employing tightness preferably steel pipe in concrete, reserve the pipeline that prestressed strand is walked, the pre-buried backing plate that can transmit immense pressure in the anchor surface concrete of front and back, after concrete reaches certain intensity, prestressed strand (high-tensile steel wires or presstressed reinforcing steel) is passed the pipeline of reservation, adopt fluid pressure type jack tension prestressed strand to certain tonnage, stress level, by ground tackle fluid pressure type jack tension power is changeed at last and be added on the backing plate pre-buried in the anchor surface concrete of front and back, thereby the anchor body concrete has been applied precompression, by being connected of ground tackle and main push-towing rope bundle thigh, main push-towing rope power is delivered to the anchor body.Be characterized in, after prestressed stretch-draw is finished, prestress pipe, anchor head poured into anticorrosion grease, protect by anticorrosion grease, prestressed strand and surrounding concrete do not have bonding.

The main deficiency of the conventional prestressing without bondn system of suspension bridge anchorage is: because it is many to form the bundle thigh of prestressed strand, easily beat strand when lashing, stretch-draw, and the mutual jam-packed of curved section, therefore can not partly substitute, can not carry out safe replacing operation, maintainability is not compared not improvement with bonding system is arranged.

Generally speaking, traditional anchorage prestress system, the main deficiency that exists is: detection, difficult in maintenance, can not under the prerequisite that guarantees bridge safety, realize the replacing attended operation of steel bundle, intermediate plate, in case prestressed strand and intermediate plate generation corrosion and damage, the safety of whole bridge and durability will be had a strong impact on.

Summary of the invention

The objective of the invention is to be to provide a kind of suspension bridge anchoring changeable formula prestressed method, method is easy, and it is convenient to change, and has realized that effectively whole bundle presstressed reinforcing steel can safeguard, changes safety, and is reliable and stable.

Another is to be to provide a kind of suspension bridge anchoring changeable formula prestressing apparatus for a purpose of the present invention, simple in structure, it is convenient to change, the pre-buried pipeline of honeycomb fashion that each strand of steel bundle can pass through respectively in pipeline separately realizes that safety changes rope, under the prerequisite that guarantees bridge safety, realize the prestressed replaceable operation of suspension bridge anchorage, improved the maintainability of anchorage and main push-towing rope anchor system, finally improved the safety and the reliability of bridge.

To achieve these goals, the present invention adopts following technical measures:

A kind of suspension bridge anchoring changeable formula prestressing force method for designing comprises that prerequisite, a later stage that two designs should be satisfied change the rope Rule of judgment and change Suo Fangfa:

1, design stage two prerequisites that must satisfy

If the main cable strand corresponding with certain bundle prestressing force is P at the maximum pull that becomes bridge operation stage (the bridge design standard is referred to as lasting situation), when becoming the bridge maintenance to change, be P ' by this main cable strand pulling force of control vehicle pass-through, the effective anchored force of prestressing tendon is F, prestressing tendon strand number is n, replaceable for realizing, should satisfy two conditions:

1) whole bundle prestressing force satisfies the lasting situation safety conditions of main cable strand

F＞k*P (formula 1)

Wherein k is lasting situation anchor system safety factor, is generally 1.2～1.5

2) single or many satisfy main cable strand transient situation safety conditions when substituting

The number of share of stock that loosens simultaneously when supposing to substitute is n ' (generally getting 1), partially safely, and by the consideration of deactivating of n '+1 strand:

$\frac{n-(n^{\′}+1)k^{\′\′}}{n}F>k^{\′}{P}^{\′}$ (formula 2)

Wherein, k ' is a transient situation anchor system safety factor, is generally 1.2

K " determine by experiment, generally gets 1.1 by the nonuniformity coefficient when being strand stretch-draw

Then design or when becoming bridge the effective anchored force F of whole bundle prestressing force should satisfy:

$F>k^{\′}{P}^{\′}\frac{n}{n-(n^{\′}+1)k^{\′\′}}$ (formula 3)

2, the later stage is judged the condition that need change rope

If the prestressed initial effectively anchored force of certain bundle is F, find that by the long-term health monitoring this Shu Youxiao anchored force is reduced to F ', then when following condition is set up, the burn into fracture has taken place in the strand of the existing individual equivalent of n ' in the expression whole bundle prestressing force (strand is counted n), has reached the condition of this Shu Jinhang being changed (number of share of stock that loosens simultaneously is n ').

$F(1-\frac{n^{\′}}{{\mathrm{nk}}^{\′\′}})\≤F^{\′}\≤F(1-\frac{(n^{\′}-1)}{{\mathrm{nk}}^{\′\′}})$ (formula 4)

Wherein n, n ', F, k ', k " etc. symbolic significance the same.

3, substitute mode is the mode of substituting, and the number of share of stock that once loosens is not more than n '.

The prestressed anchored force long term monitoring of suspension bridge anchorage both can also can be monitored part steel bundle based on random sampling or uniform sampling theory all anchoring steel bundle monitorings.

If all anchoring steel bundles are implemented to monitor, then only need actual effectively anchored force F according to each steel bundle, the Rule of judgment of pressing (formula 4) carries out.

If only to part anchoring steel Shu Jinhang sampling monitoring, then, determine whether the steel bundle that monitoring sensor is not set is done all to change according to main push-towing rope degree of safety fraction and to the chemical detection of anticorrosion grease in the pipeline.

4, change Suo Fangfa

Change the mode that Suo Caiyong is single or the 2-3 root is substituted and carry out, the radical n ' that moves back anchor satisfy transient situation safety conditions (formula 3), and concrete steps are as follows:

(1) discharges grease in front and back anchor face anchor head protective cover and the pipeline;

(2) remove the front and back protective cover;

(3) anchor face single presstressed reinforcing steel in back moves back anchor, checks, changes intermediate plate;

(4) new and old presstressed reinforcing steel connects;

(5) the anchor face extracts old presstressed reinforcing steel in the past, and draws new presstressed reinforcing steel, if the corrosion fracture of old presstressed reinforcing steel is then directly reeved;

(6) upper clip is finished this root tension of prestressed tendon;

(7) repeat (3)～(6) said process, finish this Shu Suoyou presstressed reinforcing steel and intermediate plate dismounting, replacing and stretch-draw, if desired, integral tension is to builder's tonnage again;

(8) change the protective cover sealing ring, anchor head protective cover before and after reinstalling;

(9) the anticorrosion grease of pressure injection is again finished this Shu Genghuan operation.

A kind of suspension bridge anchoring changeable formula prestressing apparatus comprises: the pre-pipe laying of honeycomb fashion, presstressed reinforcing steel, anchor plate, connect with six (many) limits shape steel sleeve, leakproof end plate, shape steel pipe limit, outsourcing six (many) limit shape steel sleeve, connection circular steel sleeve pipe spiral reinforcement under anchor slab, intermediate plate, locking baffle plate, protective cover, the anchor, anticorrosion grease.

Its annexation is: the pre-pipe laying of honeycomb fashion is embedded in the anchorage concrete, and presstressed reinforcing steel is through in the little steel pipe of the pre-pipe laying of honeycomb fashion, and by the transition joint spreading, the pre-pipe laying of honeycomb fashion two ends are connected with anchor plate by end joint between the pre-pipe laying of honeycomb fashion; Tensioned prestressing bar tightens intermediate plate and forms the self-locking anchoring to the stress of design code, anchor face and back anchor face before the pulling force of presstressed reinforcing steel passes to by intermediate plate, anchor slab; Locking baffle plate is installed in the intermediate plate end and holds out against; Protective cover is connected with preceding anchor face connector or back anchor face anchor plate and is airtight, and anticorrosion grease is poured in the space of pre-pipe laying of honeycomb fashion and protective cover.

1, anchor system is connected with main push-towing rope bundle thigh

The monitoring of anchorage prestress system, maintainability is the key factor that influences suspension bridge structural safety and life-span.Suspension bridge anchorage prestressing force is connected with main push-towing rope bundle thigh by anchor system, thereby transmits tension of main cable because main push-towing rope bundle thigh pulling force is huge, can not loose power at Cheng Qiaohou, the prestressed replacing of anchorage with not loose corresponding main push-towing rope bundle thigh, not influence bridge safety be prerequisite.

The prestressed crucial thinking of changeable type is the prestressing force strand with the anchoring of whole bundle, the minimum unit of pressing stretch-draw, anchoring is (for presstressed reinforcing steel intermediate plate anchor, for one/the root presstressed reinforcing steel), independently current pipeline is set, when satisfying maintenance under the prerequisite of (the bridge design standard is referred to as transient situation) structural safety, adopt single mode of substituting, realize replacing whole bundle prestressed cable.

Suspension bridge anchoring changeable formula prestressed constructions as shown in Figure 1, the independently current pipeline of each strand press the honeycomb fashion setting, for instance, 19 strands of corresponding 19 pipe honeycomb ducts of presstressed reinforcing steels, 37 strands of presstressed reinforcing steels corresponding 37 are managed honeycomb ducts, the rest may be inferred for other.

2, the pre-pipe laying structure of honeycomb fashion

The pre-pipe laying of prestressed strand honeycomb fashion adopts minor diameter seamless steel tube usually, press regular hexagon or intend regular hexagon and form bundle, as shown in Figure 2, the internal diameter of minor diameter seamless steel tube is determined by 2 times of the presstressed reinforcing steel area that wherein will pass through, for φ 15.24 presstressed reinforcing steels, internal diameter is got 28mm.The wall thickness of minor diameter seamless steel tube wants to satisfy the intensity needs of concrete pouring, for being positioned at the curved section part, and the radial force requirement in the time of also will satisfying steel Shu Zhangla, thickness is 3～5mm.

Adopt the plug welding welding every 2m between the seamless steel pipe, and then form cellular tube bundle assembly, for the ease of transportation and installation, tube bundle assembly length can be 9～12m, connect by transition joint again after transporting the scene to,, adopt welding manner to connect for guaranteeing seal.

The pre-buried tube end of honeycomb fashion is connected with the interface of anchor plate by end joint.For guaranteeing seal, can adopt welding manner to connect or the employing epoxy sealing.

The pre-pipe laying of honeycomb fashion has been for the per share presstressed reinforcing steel of forming the steel bundle provides an independent passage, makes that each strand presstressed reinforcing steel can not pass separately intrusively, stretch-draw separately, anchoring and attended operation separately separately.

3, honeycomb duct joint construction

Because prestressed strand is longer, the honeycomb duct segmentation is made, and on-the-spot the installation adopts joint to connect.It is accurate, airtight that the contraposition of honeycomb duct joint requires, and transition joint is constructed as Fig. 3.Six (many) limits shape steel sleeve is inserted in plug welding or the cellular steel pipe that is bundled into six (many) limits shape, docks by steel sleeve, the plug welding of honeycomb duct end and with the steel sleeve full weld, with the seal of assurance honeycomb duct to steel sleeve.

The joint bit errors will form faulting of slab ends between honeycomb duct, for avoiding faulting of slab ends the steel bundle (thigh) that navigates within is wherein caused friction or damage, the honeycomb duct of butt joint place to carry out chamfered edge.

Be connected between honeycomb duct and the anchor plate, need be converted to circle earlier, connect (weldering) with anchor plate again and connect, joint such as Fig. 4 will guarantee the seal that connects equally.

The present invention compared with prior art, have the following advantages and effect: 1) owing to form each strand presstressed reinforcing steel of steel bundle and run in the guide separately independently in the minor diameter seamless steel tube, do not disturb mutually, do not push, make that steel Shu Shouli is even, thereby improved the reliability of steel bundle; 2) by the honeycomb fashion pipeline, make the later stage to carry out stretch-draw, to change operation, thereby realized the safeguarding of whole bundle presstressed reinforcing steel, convertibility safety the sub-thread presstressed reinforcing steel, reliable and stable.

Description of drawings

Fig. 1 is a kind of suspension bridge anchoring changeable formula prestressing apparatus structure collectivity schematic diagram;

Fig. 2 cooperates schematic diagram for Fig. 1;

Fig. 3 is a honeycomb fashion embedded steel tube structural representation;

Fig. 4 is a honeycomb fashion prestress pipe transition joint structural representation;

Fig. 5 cooperates schematic diagram for Fig. 4;

Fig. 6 is honeycomb fashion prestress pipe and anchor plate end joint structural representation;

Fig. 7 is the cooperation schematic diagram of Fig. 6;

Fig. 8 is a honeycomb fashion prestress pipe joint leakproof end plate schematic diagram;

Wherein: the pre-pipe laying of 1-honeycomb fashion, 2-presstressed reinforcing steel, 3-anchor plate, 4-anchor slab, the 5-intermediate plate, the locking baffle plate of 6-, 7-protective cover, spiral reinforcement under the 8-anchor, 9-connector (forged steel), 10-connecting rod, 11-nut, anchor face (anchorage concrete) before the 12-spheric washer, 13-, anchor face behind the 14-(anchorage concrete), the anticorrosion grease of 15-, 16-connect with six (many) limits shape steel sleeve, 17-plug welding, 18-leakproof end plate, shape steel pipe limit, 19-outsourcing six (many) limit shape steel sleeve, 20-connect uses the circular steel sleeve pipe.

The specific embodiment

A kind of suspension bridge anchoring changeable formula prestressing force method for designing comprises that prerequisite, a later stage that two designs should be satisfied change the rope Rule of judgment and change Suo Fangfa:

1, design stage two prerequisites that must satisfy

If the main cable strand corresponding with certain bundle prestressing force is P at the maximum pull that becomes bridge operation stage (the bridge design standard is referred to as lasting situation), when becoming the bridge maintenance to change, be P ' by this main cable strand pulling force of control vehicle pass-through, the effective anchored force of prestressing tendon is F, prestressing tendon strand number is n, replaceable for realizing, should satisfy two conditions:

1) whole bundle prestressing force satisfies the lasting situation safety conditions of main cable strand

F＞k*P (formula 1)

Wherein k is lasting situation anchor system safety factor, is generally 1.2～1.5

2) single or many (2-3 roots) satisfy main cable strand transient situation safety conditions when substituting

The number of share of stock that loosens simultaneously when supposing to substitute is n ' (generally getting 1), partially safely, and by the consideration of deactivating of n '+1 strand:

$\frac{n-(n^{\′}+1)k^{\′\′}}{n}F>k^{\′}{P}^{\′}$ (formula 2)

Wherein, k ' is a transient situation anchor system safety factor, is generally 1.2

K " determine by experiment, generally gets 1.1 by the nonuniformity coefficient when being strand stretch-draw

Then design or when becoming bridge the effective anchored force F of whole bundle prestressing force should satisfy:

$F>k^{\′}{P}^{\′}\frac{n}{n-(n^{\′}+1)k^{\′\′}}$ (formula 3)

2, the later stage is judged the condition that need change rope

If the prestressed initial effectively anchored force of certain bundle is F, find that by the long-term health monitoring this Shu Youxiao anchored force is reduced to F ', then when following condition is set up, the burn into fracture has taken place in the strand of the existing individual equivalent of n ' in the expression whole bundle prestressing force (strand is counted n), has reached the condition of this Shu Jinhang being changed (number of share of stock that loosens simultaneously is n ').

$F(1-\frac{n^{\′}}{{\mathrm{nk}}^{\′\′}})\≤F^{\′}\≤F(1-\frac{(n^{\′}-1)}{{\mathrm{nk}}^{\′\′}})$ (formula 4)

Wherein n, n ', F, k ', k " etc. symbolic significance the same.

3, substitute mode is the mode of substituting, and the number of share of stock that once loosens is not more than n '.

The prestressed anchored force long term monitoring of suspension bridge anchorage both can also can be monitored part steel bundle based on random sampling or uniform sampling theory all anchoring steel bundle monitorings.

If all anchoring steel bundles are implemented to monitor, then only need actual effectively anchored force F according to each steel bundle, the Rule of judgment of pressing (formula 4) carries out.

If only to part anchoring steel Shu Jinhang sampling monitoring, then, determine whether the steel bundle that monitoring sensor is not set is done all to change according to main push-towing rope degree of safety fraction and to the chemical detection of anticorrosion grease in the pipeline.

4, change Suo Fangfa

Change 1 of Suo Caiyong or 2 or 3 modes of substituting are carried out, the radical n ' that moves back anchor satisfy transient situation safety conditions (formula 3), and concrete steps are as follows:

(1) discharges grease in front and back anchor face anchor head protective cover and the pipeline;

(2) remove the front and back protective cover;

(3) anchor face single presstressed reinforcing steel in back moves back anchor, checks, changes intermediate plate;

(4) new and old presstressed reinforcing steel connects;

(5) the anchor face extracts old presstressed reinforcing steel in the past, and draws new presstressed reinforcing steel, if the corrosion fracture of old presstressed reinforcing steel is then directly reeved;

(6) upper clip is finished this root tension of prestressed tendon;

(7) repeat (3)～(6) said process, finish this Shu Suoyou presstressed reinforcing steel and intermediate plate dismounting, replacing and stretch-draw, if desired, integral tension is to builder's tonnage again;

(8) change the protective cover sealing ring, anchor head protective cover before and after reinstalling;

(9) the anticorrosion grease of pressure injection is again finished this Shu Genghuan operation.

According to Fig. 1, Fig. 2, Fig. 3, Fig. 4, Fig. 5 as can be known, a kind of suspension bridge anchoring changeable formula prestressing apparatus comprises: the pre-pipe laying 1 of honeycomb fashion, presstressed reinforcing steel 2, anchor plate 3, connect with six (many) limits shape steel sleeve 16, leakproof end plate 18, shape steel pipe limit, outsourcing six (many) limit shape steel sleeve 19, connection usefulness circular steel sleeve pipe 20 spiral reinforcement 8 under anchor slab 4, intermediate plate 5, locking baffle plate 6, protective cover 7, the anchor, anticorrosion grease 15.

Its annexation is: the pre-pipe laying 1 of honeycomb fashion is embedded in the anchorage concrete, presstressed reinforcing steel 2 is through in the little steel pipe of the pre-pipe laying 1 of honeycomb fashion, be connected with hexagon steel sleeve 16, plug welding 17, leakproof end plate 18, outsourcing hexagon steel pipe 19 by transition joint between the pre-pipe laying 1 of honeycomb fashion, the pre-pipe laying of honeycomb fashion 1 two ends are connected with anchor plate 3 by the plug welding on the end joint 17, leakproof end plate 18, circular steel sleeve pipe 20; Tensioned prestressing bar 2 tightens intermediate plate 5 and forms the self-locking anchoring to the stress of design code, anchor face 13 and back anchor face 14 before the pulling force of presstressed reinforcing steel passes to by intermediate plate 5, anchor slab 4; Locking baffle plate 6 is installed in intermediate plate 5 ends and holds out against; Protective cover 7 is connected with preceding anchor face connector 9 or back anchor face anchor plate 3 and is airtight, and anticorrosion grease 15 is poured in the space of pre-pipe laying 1 of honeycomb fashion and protective cover 7.

Anchor face 13 and back anchor face 14 before anchor plate 3 is placed in, mounted connector 9, anchor slab 4, tensioned prestressing bar 2 in the steel pipe.Plug welding 17 or be bundled into hexagonal cellular steel pipe and insert polygonal steel pipe 19 connects by steel sleeve, cellular tube end plug welding 17 and steel sleeve full weld, and honeycomb duct is connected with anchor plate 3, is converted to circle and is connected with anchor plate 3.The pre-pipe laying 1 of described prestressed strand honeycomb fashion adopts seamless steel pipe, press regular hexagon or intend regular hexagon composition bundle, seamless steel pipe adopts plug welding 17 welding, form cellular tube bundle assembly, the honeycomb duct end is connected by the interface of end joint with anchor plate 3, connects or the employing epoxy sealing with welding manner.

First mounting method: the pre-pipe laying 1 of honeycomb fashion that little steel pipe is formed is before cast anchorage concrete, set in advance in design named pipe position, anchor face 13 and back anchor face 14 before anchor plate 3 is placed in, cast anchorage concrete, detect the seal of the pre-pipe laying 1 of honeycomb fashion, after qualified presstressed reinforcing steel 2 is through in the little steel pipe of the pre-pipe laying 1 of honeycomb fashion, mounted connector 9, anchor slab 4, tensioned prestressing bar 2 is to the stress of design code, tighten intermediate plate and form the self-locking anchoring, finish the stretch-draw and the anchoring of all presstressed reinforcing steels 2 successively, baffle plate is loosened in installation, protective cover is installed, is adopted the anticorrosion grease 15 of oil pump pressure injection to be full of all spaces of pre-pipe laying of honeycomb fashion and protective cover, promptly finish prestressed installation and construction.

Claims (1)

1, the prestressed method of a kind of suspension bridge anchoring changeable formula, it comprises the following steps:

The condition of A, design stage:

The main cable strand that designs certain bundle prestressing force correspondence is P at the pulling force that becomes bridge operation stage, when becoming the bridge maintenance to change, be P ' by this main cable strand pulling force of control vehicle pass-through, get the dead load pulling force partially safely, the effective anchored force of prestressing tendon is F, prestressing tendon strand number is n, replaceable for realizing, should satisfy two prerequisites in the design stage:

1) whole bundle prestressing force satisfies the lasting situation safety conditions of main cable strand

F＞k*P (I)

Wherein k is lasting situation anchor system safety factor, is 1.2～1.5

2) single or many satisfy main cable strand transient situation safety conditions when substituting

The number of share of stock that loosens simultaneously when substituting is n ', and minimum gets 1, withdraws from by n '+1 strand:

$\frac{n-(n^{\′}+1)k^{\′\′}}{n}F>k^{\′}{P}^{\′}---\left(\mathrm{II}\right)$

Wherein, k ' is a transient situation anchor system safety factor, is 1.2

" nonuniformity coefficient when being strand stretch-draw gets 1.1 to k

Whole bundle prestress anchoraging power when design or one-tenth bridge:

$F>k^{\′}{P}^{\′}\frac{n}{n-(n^{\′}+1)k^{\′\′}}---\left(\mathrm{III}\right)$

B, later stage are judged the condition of changing rope

The prestressed effective anchored force of design bundle is F, find that by the long-term health monitoring this Shu Youxiao anchored force is reduced to F ', when following condition was set up, the burn into fracture had taken place in the strand of the existing individual equivalent of n ' in the whole bundle of the expression prestressing force, has reached the condition that this Shu Jinhang is changed

$F(1-\frac{n^{\′}}{{\mathrm{nk}}^{\′\′}})\≤F^{\′}\≤F(1-\frac{(n^{\′}-1)}{{\mathrm{nk}}^{\′\′}})---\left(\mathrm{IV}\right)$

C, substitute mode are the mode of substituting, and the number of share of stock that once loosens is not more than n ':

The prestressed anchored force long term monitoring of suspension bridge anchorage, to all anchoring steel bundle monitorings, random sampling or the monitoring of uniform sampling steel bundle; Or

All anchoring steel bundles are implemented monitoring, and according to the actual effectively anchored force F of each steel bundle, by formula the Rule of judgment of IV carries out; Or

To anchoring steel Shu Jinhang sampling monitoring,, determine the steel bundle that monitoring sensor is not set is done all to change according to the main push-towing rope degree of safety and to the chemical detection of anticorrosion grease in the pipeline;

D, change Suo Fangfa

Change the mode that Suo Caiyong is single or the 2-3 root is substituted and carry out, the radical n ' that moves back anchor satisfy transient situation safety conditions formula III, and concrete steps are as follows:

(1) discharges grease in front and back anchor face anchor head protective cover and the pipeline;

(2) remove the front and back protective cover;

(3) anchor face single presstressed reinforcing steel in back moves back anchor, checks, changes intermediate plate;

(4) new and old presstressed reinforcing steel connects;

(5) the anchor face extracts old presstressed reinforcing steel in the past, and draws new presstressed reinforcing steel, and the corrosion fracture of old presstressed reinforcing steel is then directly reeved;

(6) upper clip is finished this root tension of prestressed tendon;

(7) repeat (3)～(6) said process, finish this Shu Suoyou presstressed reinforcing steel and intermediate plate dismounting, replacing and stretch-draw, integral tension is to builder's tonnage again;

(8) change the protective cover sealing ring, anchor head protective cover before and after reinstalling;

(9) the anticorrosion grease of pressure injection is again finished this Shu Genghuan operation.

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