CN101435184B - Method for actively reinforcing wide-span concrete case beam bridge web - Google Patents

Abstract

The invention relates to a reinforcing and repairing measure for existing concrete box girder bridges, and discloses a method for actively reinforcing a large-span concrete box girder bridge web plate, comprising the following steps: (1) according to the structural parameters of the concrete box girder bridge and by adopting a structural analysis method and corresponding general or special analysis software, a finite element model of a simulated reinforced plate shell concrete box girder bridge is established, thus obtaining the magnitude of the main pulling stress, the vertical stress, the longitudinal stress and the shearing stress of the box girder web plate before reinforcement and the distribution rule thereof; (2) the difference between the main pulling stress and the limited value allowed by the 'Standard' is compared to obtain the target increment value of the vertical stress of the bridge girder, and the actual reinforcement parameters are determined according to the target value; (3) drilling is carried out on the upper margin and the lower margin of the concrete box girder web plate, steel strands are installed and transversally stretched; (4) a wedge block A is used for jacking up the steel strands, then a jack is used for jacking up and pulling the steel strands to the allowed tensioning force, and the steel strands are tensioned one by one; and (5) crack is mended.

Description

A kind of method of active reinforcing wide-span concrete box beam bridge web

Technical field:

The present invention relates to reclamation activities, be specifically related to a kind of external prestressing strengthening restorative procedure of concrete box beam bridge web existing concrete-bridge.

Background technology:

Large-span concrete box girder bridge (continuous box girder, continuous rigid frame) web cracking is bridge engineering circle one of question of common concern in recent years, also is a kind of thoroughly bridge defect of radical cure that is difficult to.Reasons such as concrete box web cracking generally shows as the abdomen shear crack, and harmfulness is bigger, and its reason is many and vertical prestressing bar stretch-draw is not in place, anchoring structure is improper cause vertical prestressing σ _yThereby lose the excessive principal tensile stress σ that causes _TpIt is relevant to transfinite.Because concrete box-beam bridge dead load proportion is big and can't unload, during reinforcement and strengthening, also be difficult to the complete closed traffic to reduce the live load effect, therefore, in case the concrete box web ftractures because of vertical prestressing is not enough, it is all very difficult from aspects such as material, structure, construction technologies to apply vertical prestressing once more.

Existing " the concrete structure reinforcement technical specification " of China (CECS25-1990) and the reinforcement means that adopts in the project practices at home and abroad mainly contain: enlarging section reinforcing method, encased steel plate reinforcing method, affixing carbon fabric (plate) reinforcing method, change structure stress system method and prestressed reinforcement method etc.Wherein, enlarging section reinforcing method, encased steel plate reinforcing method, affixing carbon fabric (plate) reinforcing method all belong to the category of passive reinforcing, this method can improve the ultimate strength of structure effectively, but can not improve its applied stress situation, therefore, adopting behind the above-mentioned passive reinforcement means reinforced concrete case web once more, the cracking person also has no lack of precedents.Restricted by factor such as structural shape, the reinforcement means that changes structure force path or stress system often is difficult to use in the reinforcement and strengthening of concrete box beam bridge web.The prestressed reinforcement method is a kind of active reinforcement means, this method not only can significantly improve the ultimate strength of structure, and can change the applied stress situation of structure, the expansion of prevention structural cracks effectively, but for the web of concrete box girder, the prestressed reinforcement method exists such as prestressing tendon (or finish rolling deformed bar) anchoring nowhere, tensioning equipment and technical difficulty such as is difficult to lay, method for stretching technology is inapplicable, after causing large-span concrete case web because of the not enough cracking of vertical prestressing, engineering circle is usually felt simply helpless; And on the other hand, the influence of factors such as (" highway reinforced concrete and prestressed concrete bridge are contained design specifications " (JTJ023-85)) perfect inadequately, construction quality, overload of vehicle because former design specifications, web cracking has become one of common disease of China's large-span concrete box girder bridge, presses for proposition, improves the method for the vertical prestressing reinforcement and strengthening of case web.

Summary of the invention:

Technical problem to be solved by this invention provides a kind of active reinforcement means of concrete box beam bridge web, advantages such as this method has flexible arrangement, power transmission is even, tensioning equipment is light and handy, easy construction, the easy realization of monitoring.

The technical scheme that the present invention addresses the above problem is as described below:

A kind of method of active reinforcing wide-span concrete box beam bridge web, this method comprises the following steps:

(1), carry out the stress analysis of normal operational phase according to following steps and calculate according to the structural parameters of concrete box-beam bridge:

(1.1) adopt structure analysis method and corresponding universal or special analysis software SAP2000 or ANSYS to set up the plate shell finite element model of intending the reinforced concrete box girder bridge;

(1.2) utilize the load of bridge construction to influence line, find out the least favorable mobile load distributing position of this bridge;

(1.3) utilize described universal or special analysis software to calculate to reinforce before the control cross section case web that produces of dead load and least favorable mobile load stress state (usually, the control cross section of large-span concrete box girder bridge comprises the fulcrum cross section of main span, end bay, main span and end bay spaning middle section, 1/8,1/4,3/8 uniform section of main span and end bay span), obtain the case web and reinforce preceding principal tensile stress σ _Tp1, vertical stress σ _Y1, longitudinal stress σ _xWith shear stress τ _XyThe value and the regularity of distribution thereof;

(1.4) compare principal tensile stress σ _Tp1Allow limit value [σ with " highway reinforced concrete and prestressed concrete bridge are contained design specifications " (JTGD62-2004 is hereinafter to be referred as " standard ") _Tp] difference, determine case web principal tensile stress increment desired value [Δ σ by following formula (I) _Tp]

[Δσ _tp]≥σ _tp1—[σ _tp] (I)

Solve vertical stress increment desired value [Δ σ by following formula (II) then _y]

$\left[{\mathrm{\&Delta;\&sigma;}}_y\right]=\frac{{\mathrm{\&tau;}}_{\mathrm{<figure-callout\; id="2"\; label="xy"\; filenames="H2008102196868E00013.png,H2008102196868E00032.png"\; state="\{\{state\}\}">xy</figure-callout>}}^2+{\mathrm{\&sigma;}}_{\mathrm{<figure-callout\; id="2"\; label="tp"\; filenames="H2008102196868E00013.png,H2008102196868E00032.png"\; state="\{\{state\}\}">tp</figure-callout>}2}\&times;{\mathrm{\&sigma;}}_x-{\mathrm{\&sigma;}}_{\mathrm{<figure-callout\; id="2"\; label="tp"\; filenames="H2008102196868E00013.png,H2008102196868E00032.png"\; state="\{\{state\}\}">tp</figure-callout>}2}^2}{{\mathrm{\&sigma;}}_x-{\mathrm{\&sigma;}}_{\mathrm{tp}2}}-{\mathrm{\&sigma;}}_{y1}---\left(\mathrm{II}\right)$

(II) in the formula, σ _Tp2Be the principal tensile stress after reinforcing, σ _Tp2=σ _Tp1+ [Δ σ _Tp];

(2) solve vertical stress increment desired value [Δ σ according to formula (II) earlier _y], preliminary election steel strand specification, radical and corresponding ground tackle, steel strand with preliminary election allow stretching force to be applied to the correspondence position of plate shell (or block) finite element analysis model again, adopt described universal or special analysis software that constructed analytical model is carried out analytical calculation then; When calculate vertical stress increment Delta σ _YcMore than or equal to [Δ σ _y] and Δ σ _Y1During sum, institute's preliminary election steel strand specification, radical and the spacing of evenly arranging promptly are defined as actual reinforcing parameter, wherein Δ σ _Y1Be vertical prestressing loss sum in the stretching process;

(3) according to determined actual selection of parameter steel strand and the ground tackle thereof reinforced of step (2), lower edge boring on the concrete box web, two of each steel strand is passed respectively in two holes of being bored on the last lower edge of concrete box web, ground tackle and tension are installed;

(4) interleave into wedge A steel strand jack-up at steel strand and concrete box web earlier, then in the other jack of installing of wedge A, start jack top drawing steel stranded wire to allowing stretching force, replace jack with another wedge B again, jack is moved between next root steel strand and the concrete box web, each steel strand of stretch-draw one by one, and synchronously with the true vertical stress increment of stress-strain test instrument monitoring web, the feasible calculated value of using the detected value of stress-strain test instrument more than or equal to formula (II) in the step (1.4);

(5) look existing crack width size,, adopt chemical grouting method to mend a split,, adopt surperficial enclosure method to mend a split for the crack of width less than 0.2mm for the crack of width greater than 0.2mm.

Steel strand of the present invention can be single steel strands, also can be the steel wire bundles that many steel strand are formed.

Method of the present invention, wherein step (1.3) obtains the principal tensile stress σ before the case web is reinforced in analytical calculation _Tp1, vertical stress σ _Y1, longitudinal stress σ _xWith shear stress τ _XyAfter, their value is tabulating, so that with principal tensile stress σ _Tp1Allow limit value [σ with " standard " _Tp] relatively, the variation of web stress state before and after comparative analysis is reinforced.

The method of the invention, wherein step (4) is in the true vertical stress increment with stress-strain test instrument monitoring web, with steel ruler monitoring steel strand lateral displacement, make the actual lateral displacement of each steel strand more than or equal to calculated value, so that utilize the measurement of steel strand lateral displacement to come verification stretch-draw effect, guarantee the transverse stretching steel strand reach expection web stress improve target.

Method of the present invention, the wherein described vertical stress loss of step (2) sum Δ σ _Y1Equal the ground tackle loss The steel strand relaxation loss

, elastic compression loss

Lose with the cushion block difference in height

Sum accounts for vertical stress increment desired value [Δ σ _y] 20%, so the detected value of stress-strain test instrument should be more than or equal to 120% of the calculated value of formula (II) in the step (1.4) in the step (4).Above-mentioned ground tackle loss Relaxation loss

Lose with elastic compression

Computational methods referring to " standard ", the loss of above-mentioned cushion block difference in height can adopt following formula (III) to calculate

${\mathrm{\&Delta;\&sigma;}}_{\mathrm{<figure-callout\; id="1"\; label="y"\; filenames="H2008102196868E00032.png,H2008102196868E00052.png"\; state="\{\{state\}\}">y</figure-callout>}1}^4=\frac{3\mathrm{El}}{L}\&times;(\sqrt{4\&times;{\left(\frac{{\mathrm{\&Delta;}}_2}{l}\right)}^2+1}-\sqrt{4\&times;{\left(\frac{{\mathrm{\&Delta;}}_1}{l}\right)}^2+1})---\left(\mathrm{III}\right)$

(III) l is that steel strand are long only in the formula, and L is the length overall of steel strand, and E is the modulus of elasticity of steel strand, Δ ₁Be pairing steel strand lateral displacement behind the insertion wedge B, Δ ₂For drawing the pairing steel strand lateral displacement in back in the jack top.

Method of the present invention, wherein the described steel strand lateral displacement of step (4) Δ can adopt following formula (IV) to calculate

$\mathrm{\&Delta;}=\frac{\mathrm{<figure-callout\; id="2"\; label="L"\; filenames="H2008102196868E00013.png,H2008102196868E00032.png"\; state="\{\{state\}\}">L</figure-callout>}}{2}\&times;\sqrt{{(\frac{{\mathrm{\&sigma;}}_n}{E}+\frac{l}{L})}^2-{\left(\frac{l}{L}\right)}^2}---\left(\mathrm{IV}\right)$

(IV) in the formula, σ _nBe the control tension stress of steel strand, general press " standard " is taken as 1395MPa, all the other symbolic significance cotypes (III).

In the inventive method, described ground tackle can be the flat anchor of using always of clip type, and as the flat anchor of OVM15-3 type, described stress-strain test instrument can adopt resistance strain gauge or steel chord type strain gauge, also can be to adopt other principle to measure the instrument of concrete stress.

Method of the present invention initiatively adjusts, improves the stress state of concrete box web by the transverse stretching steel strand, thereby makes the concrete box beam bridge web stress state be able to initiatively adjust, to stop the expansion of web shear crack effectively.In addition, method of the present invention also has following outstanding advantage: need not unloading when 1. constructing, can not influence traffic during the reparation; 2. owing to take the mode of external dispersed placement, thereby have simple structure, tensioning equipment is light and handy, and easy construction is with low cost, can carry out repeatedly replenishing advantages such as stretch-draw.

Description of drawings:

The yellow gush forth bridge elevation in Lanxi, Zhejiang and bridge fulcrum and bridge span centre profile that Fig. 1 and Fig. 2 initiatively reinforce for adopting the inventive method to carry out, wherein, dimensioning unit of institute is a rice (m) among elevation Fig. 1, and dimensioning unit of institute is centimetre (cm) among bridge span centre profile Fig. 2.

Fig. 3 is the case web FRACTURE CHARACTERISTICS statistical chart of Fig. 1 and Fig. 2 bridge.

Fig. 4 is the schematic diagram of the inboard fractue spacing form of case web of Fig. 1 and Fig. 2 bridge.

Fig. 5 is the schematic diagram of crack, the case web outside distribution form of Fig. 1 and Fig. 2 bridge.

Fig. 6 is the finite element entity analysis model scenograph that Fig. 1 and Fig. 2 bridge intend reinforcing sections.

Fig. 7 reinforces plan shown in Figure 6 when reinforcing sections, the vertical stress increment isogram that the stretch-draw steel strand are produced for adopting the inventive method.

Fig. 8 is the finite element space plate model of element figure that Fig. 1 and Fig. 2 bridge intend reinforcing sections.

Fig. 9～15 are the process structure schematic diagram of the inventive method implementation process, and wherein, Fig. 9 is a kind of cross section structure schematic diagram of concrete concrete box web, and Figure 10 is the left view of Fig. 9; Figure 11 is for inserting the view of wedge A; Figure 12 is a process schematic diagram of replacing wedge A with jack; Figure 13 is for to carry out the tensile state schematic diagram with jack; Figure 14 is for replacing the process schematic diagram of jack with wedge B; The state diagram that Figure 15 finishes for stretching process.

The specific embodiment:

Below be example with the reinforcing of the concrete continuous box girder bridge web of the yellow gush forth bridge in Lanxi, Zhejiang Province, describe specific implementation method of the present invention in detail.

The yellow gush forth bridge in Lanxi, Zhejiang Province is positioned on the Lanjiang River in Lanxi City west side, is open to the traffic in July, 1997.The long 344m of this bridge master bridge strides the footpath and is combined as 52m+3 * 80m+52m.Superstructure is the prestressed concrete continuous box girder bridge, the case beam adopts the C50 concrete, the single box single chamber cross section, the wide 8m of case, the wide 15.7m of case back, the wide 3.85m of frange plate, fulcrum case deck-molding 5m, span centre deck-molding 2.4m, to span centre 35cm, structural dimensions is referring to illustrated in figures 1 and 2 by the 60cm gradual change at fulcrum place for web thickness.

After testing, this serious downwarp in spanning middle part, there is the shear crack than comparatively dense in the case web, and is wherein in the majority above the shear crack that " standard " limit value produces with principal tensile stress especially.Totally 1229 in full-bridge case web crack, 1081 in its raising middle flask endosternum crack accounts for 88% of web crack, 148 in the outer web crack of case accounts for 12% of web crack, concrete statistical law as shown in Figure 3, distribution characteristics is as shown in Figure 4 and Figure 5.Now in conjunction with other diseases, adopt the inventive method that this bridge case web is reinforced, concrete steps are as follows.

A. determine vertical stress increment desired value

At first,, adopt ANSYS software, set up the space plate shell finite element analytical model of this bridge according to following steps: 1. import this bridge control node three-dimensional coordinate, generate the control node according to this bridge real size and detail structure; 2. the circulate control node of this bridge, the line of generating structure and face finally generate computation model and check; 3. constitute according to this bridge real material, define various unit material parameters, division unit; 4. according to these bridge seat actual conditions, apply the bearing constraint information.Wherein, the top board of case beam, base plate and web all adopt shell unit shell63 to simulate, and the division of unit is as far as possible evenly reasonable, and fully reflects this bridge actual configuration.In this example, yellow gush forth bridge case beam has been divided 7694 plate unit altogether, 9442 nodes, and the FEM (finite element) model of this bridge is as shown in Figure 8.

Secondly, utilize the computation model of having set up, utilize the load of bridge construction to influence line, according to the mobile load arrangement of " standard ", find out the least favorable mobile load distributing position of this bridge, mobile load acts on this position can make yellow gush forth bridge control cross section produce maximum mobile load moment of flexure.Usually, the control cross section comprises the fulcrum cross section of main span, end bay, main span and end bay spaning middle section, 1/8,1/4,3/8 uniform section of main span and end bay span.

Once more, calculate the principal tensile stress σ of the case web of reinforcing preceding dead load and the generation of least favorable mobile load according to following steps _Tp1, vertical stress σ _Y1, longitudinal stress σ _xAnd shear stress τ _XyDeng, and result of calculation gathered be organized into table.Detailed process is as described below: 1. apply dead load on the unit of plate shell analysis model or node; 2. according to the live load mode of action and the least favorable mobile load active position of " standard " defined, import the active position and the size of live load; 3. the pattern of finding the solution is set to static(al) and finds the solution pattern, operation ANSYS program solution; 4. enter ANSYS post processing menu, extract result of calculation.In this example, calculate the web stress state in this bridge main span span 1/4 cross section see Table 1, under the operating mode of least favorable dead load+mobile load, the maximum principal tensile stress σ of this bridge case web _TpBe 3.72MPa.

At last, compare principal tensile stress σ _Tp1Allow limit value [σ with " standard " _Tp] difference, formula described in the content (I) is determined web principal tensile stress increment desired value [Δ σ according to the present invention _Tp].In this example, calculate the actual maximum principal tensile stress σ of case web _Tp1Be 3.72MPa, surpass " standard " principal tensile stress limit value [σ _Tp] ([σ _Tp]=2.50MPa) is the regulation of 1.22MPa, therefore determines web principal tensile stress increment desired value [Δ σ _Tp] 〉=1.22MPa; Then according to formula described in the summary of the invention (II), calculate web vertical stress increment desired value [Δ σ _y] 〉=2.10MPa.

Main span span 1/4 cross section web stress summary sheet (MPa) under the operating mode of table 1 least favorable dead load+mobile load

Major principal stress σ tp1	σ x	σ y1	τ xy
				3.72	7.32	4.90	2.06

B. determine the related parameter that has of reinforcing design

At first, according to the determined vertical stress increment of step a desired value [Δ σ _y], choose steel strand specification and corresponding ground tackle.In this example, steel strand adopt 3 Φ 15.24, and corresponding ground tackle is the flat anchor of OVM15-3 type, steel strand tension proof stress σ _n, elastic modulus E is by " standard " value.

Secondly, draft the layout scope and the arrangement pitch D of steel wire bundle.In this example, steel strand layout scope is for to locate from theoretical fulcrum 5m to 20m, and arrangement pitch equidistantly carries out tentative calculation by 1.0m, 1.5m, 2.0m's, when D=1.0m, partly strides monolateral layout 16 bundle steel strand.

Once more, utilize the ANSYS analysis software, according to yellow gush forth bridge case beam actual configuration, set up the box girder segment finite element entity analysis model of reinforcing section, the consolidation effect of selected reinforcing parameter is calculated in sunykatuib analysis, and the key step of this process is:

(1) sets up the box girder segment finite element entity analysis model of reinforcing section

1. input structure control node three-dimensional coordinate generates the control node; 2. the control node of loop structure, the line of generating structure and face finally generate computation model and check; 3. constitute according to this bridge real material, define various unit material parameters, division unit; 4. according to these bridge seat actual conditions, apply the bearing constraint information; 5. according to the position of the determined steel wire bundle of preamble, import the node coordinate of steel strand, circulation generates all steel strand node and unit; 6. with the node coupling of corresponding node of concrete web and steel strand, make it become integral body.In this example, box girder segment concrete web, top board, base plate adopt the Solid65 solid element to divide simulation, steel strand adopt the Link8 bar unit to divide simulation, steel strand and concrete adopt the mode of cell node coupling, so that both compatibilities of deformation, stressed unanimity, computation model is divided 50351 nodes and 33382 unit altogether.The case beam finite element entity analysis model scenograph of this routine resulting plan reinforcing sections as shown in Figure 6.

(2) consolidation effect is calculated in sunykatuib analysis

1. steel strand are applied lateral displacement, the masterpiece that above-mentioned steel strand transverse stretching is produced is used on the concrete web of analytical model; 2. the pattern of finding the solution is set to static(al) and finds the solution pattern, operation ANSYS program solution; 3. enter ANSYS post processing menu, extract result of calculation.In this example, result of calculation shows: when steel strand arrangement pitch D is 1.0m, can make web vertical stress increment Δ σ by the transverse stretching steel strand _YcReach 4.14～6.79MPa, deduct about 20%[Δ σ _y] loss of prestress, still can satisfy vertical stress increment desired value [Δ σ _yThe target of] 〉=2.10MPa illustrates to apply prestressing force that web vertical stress is improved effect is more remarkable.When Fig. 7 is steel strand arrangement pitch D=1.0m, case web vertical stress incremental computations result.

At last, comprehensive above-mentioned reinforcing analysis result can be determined the related parameter that has of reinforcing design.In this example, steel strand adopt 3 Φ 15.24, and ground tackle adopts the flat anchor of OVM15-3 type, and steel strand layout scope is in the scope of theoretical fulcrum 5m to 20m, and steel strand arrangement pitch D gets 1.0m, and full-bridge is arranged 2 * 8 * 16=256 bundle steel strand altogether.

C. implement the specification and the arrangement pitch D of preparation according to the determined steel strand 4 of step b, lower edge drills the hole 2 (referring to Fig. 9 and Figure 10) of steel strand 4 on concrete box web 1, be to connect steel strand 4 again, OVM15-3 type strand tapered anchorage 5 (referring to Figure 11) are installed; Wherein said hole 2 15 degree that tilt up and down respectively form acute angle and hurt steel strand 4 to avoid the hole 2 and the sidewall of concrete box web 1.

D. stretching construction inserts wedge A at steel strand 4 and 1 of concrete box web earlier, with steel strand 4 jack-up (referring to Figure 11), then in the other jack 6 (referring to Figure 12) of installing of wedge A, start jack 6 and hold out against steel strand 4 (referring to Figure 13), replace jack 6 (referring to Figure 14 and Figure 15) with another wedge B again, as above-mentioned method jack 6 is moved to down between steel strand 4 and the concrete box web 1 then, strain each bundle steel strand 4 one by one, and adopt the stress-strain test instrument to monitor the true vertical stress increment of web synchronously, adopt two index monitoring modes of steel ruler monitoring steel strand lateral displacement, produce a desired effect to guarantee the transverse stretching steel strand.In this example, calculate to such an extent that the calculated value of the lateral displacement that produces of each steel strand tension sees Table 2 according to formula described in the summary of the invention (IV), when recording each actual lateral displacement of restrainting steel strand with steel ruler, promptly meet the requirements, otherwise should replenish stretch-draw more than or equal to the calculated value in the table 2.In this example, after all steel strand 4 stretch-draw are finished, the vertical stress increment that web produces is 3.23～5.43MPa (near fulcrum cross section person is lower limit, is higher limit near the spaning middle section person), satisfies the re-set target value of vertical stress increment more than or equal to 2.10MPa.

The lateral displacement of table 2 steel strand

Apart from pivot distance (m)	5.0	6.0	7.0	8.0	9.0	10.0	11.0	12.0
									The steel wire bundle numbering	1	2	3	4	5	6	7	8
Steel strand lateral displacement Δ (mm)	200.8	193.0	185.4	178.1	170.8	163.9	157.2	150.6
									Apart from pivot distance (m)	13.0	14.0	15.0	16.0	17.0	18.0	19.0	20.0
The steel wire bundle numbering	9	10	11	12	13	14	15	16
									Steel strand lateral displacement Δ (mm)	144.3	138.2	132.2	125.3	117.8	110.6	103.6	96.9

E. mend a split according to every crack width size,, adopt chemical grouting method to mend a split 3 for the crack of width greater than 0.2mm; For the crack of width, adopt surperficial enclosure method to repair less than 0.2mm.

Claims (4)

1. method of reinforcing wide-span concrete box beam bridge web initiatively, this method comprises the following steps:

(1), carry out the stress analysis of normal operational phase according to following steps and calculate according to the structural parameters of concrete box-beam bridge:

(1.1) adopt structure analysis method and corresponding analysis software SAP2000 or ANSYS to set up the FEM (finite element) model of intending gusset plate shell concrete box-beam bridge;

(1.2) utilize the load of bridge construction to influence line, find out the least favorable mobile load distributing position of this bridge;

(1.3) utilize described analysis software to calculate the stress state of the control cross section case web of preceding dead load of reinforcing and the generation of least favorable mobile load, obtain the principal tensile stress σ before the case web is reinforced _Tp1, vertical stress σ _Y1, longitudinal stress σ _xWith shear stress τ _XyThe value and the regularity of distribution thereof;

(1.4) compare principal tensile stress σ _Tp1(JTGD62-2004) allow limit value [σ with " highway reinforced concrete and prestressed concrete bridge contain design specifications " _Tp] difference, determine case web principal tensile stress increment desired value [Δ σ by following formula (I) _Tp]

[Δσ _tp]≥σ _tp1-[σ _tp] (I)

Solve vertical stress increment desired value [Δ σ by following formula (II) then _y]

(II) in the formula, σ _Tp2Be the principal tensile stress after reinforcing, σ _Tp2=σ _Tp1+ [Δ σ _Tp];

(2) solve vertical stress increment desired value [Δ σ according to formula (II) earlier _y], preliminary election steel strand specification, radical and corresponding ground tackle, the steel strand with preliminary election allow stretching force to be applied to the correspondence position of plate shell finite element analytical model again, adopt described analysis software that constructed analytical model is carried out analytical calculation then; When calculate vertical stress increment Delta σ _YcMore than or equal to [Δ σ _y] and Δ σ _Y1During sum, institute's preliminary election steel strand specification, radical and the spacing of evenly arranging promptly are defined as actual reinforcing parameter, wherein Δ σ _Y1Be vertical prestressing loss sum in the stretching process;

(3) according to determined actual selection of parameter steel strand and the ground tackle thereof reinforced of step (2), lower edge boring on the concrete box web, two of each steel strand is passed respectively in two holes of being bored on the last lower edge of concrete box web, ground tackle and tension are installed;

(4) interleave into wedge A steel strand jack-up at steel strand and concrete box web earlier, then in the other jack of installing of wedge A, start jack top drawing steel stranded wire to allowing stretching force, replace jack with another wedge B again, then jack is moved between next root steel strand and the concrete box web, each steel strand of stretch-draw one by one, and, make the detected value of stress-strain test instrument more than or equal to the calculated value of formula (II) in the step (1.4) synchronously with the true vertical stress increment of stress-strain test instrument monitoring web;

(5) look existing crack width size,, adopt chemical grouting method to mend a split,, adopt surperficial enclosure method to mend a split for the crack of width less than 0.2mm for the crack of width greater than 0.2mm.

2. the method for a kind of active reinforcing wide-span concrete box beam bridge web as claimed in claim 1 is characterized in that the principal tensile stress σ of described step (1.3) before analytical calculation obtains the reinforcing of case web _Tp1, vertical stress σ _Y1, longitudinal stress σ _xWith shear stress τ _XyAfter, their value is tabulating.

3. the method for a kind of active reinforcing wide-span concrete box beam bridge web as claimed in claim 1, it is characterized in that described step (4), in true vertical stress increment with stress-strain test instrument monitoring web, with steel ruler monitoring steel strand lateral displacement, make the actual lateral displacement of each steel strand more than or equal to calculated value.

4. the method for a kind of active reinforcing wide-span concrete box beam bridge web as claimed in claim 1, the detected value that it is characterized in that the stress-strain test instrument described in the described step (4) equal formula (II) in the step (1.4) calculated value 120%.

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