CN101435183A - Method and apparatus for actively reinforcing wide-span concrete case beam bridge web - Google Patents
Method and apparatus for actively reinforcing wide-span concrete case beam bridge web Download PDFInfo
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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) a stretching device is anchored at the upper margin and the lower margin of the concrete box girder web plate, and mild steel wire bundles are tied to carry out stretching; (4) the crank of a hand-operated winch in the stretching device is shaken to respectively stretch every mild steel wire bundle, and when the actual vertical stress increment of the box girder web plate is more than or equal to the theoretical calculated value, a snib is inserted and the stretching hand-operated winch is fixed; and (5) crack is mended.
Description
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 method of active reinforced concrete box girder bridge web, advantages such as this invention has flexible arrangement, power transmission is even, tensioning equipment is light and handy, stretch-draw is easy, 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 the normal operational phase of concrete box-beam bridge 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 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
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]
(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], the specification of the stone dead wire of stone dead wire bundle, the radical and the arrangement pitch of mild steel tow are formed in preliminary election, allow stretching force to be applied to the correspondence position of plate shell finite element analytical model on the mild steel tow 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 is formed the specification of the stone dead wire of stone dead wire bundle, the radical of mild steel tow and the spacing that the mild steel tow is evenly arranged and promptly is defined as actual reinforcing parameter, wherein Δ σ
Y1Be vertical prestressing loss sum in the stretching process;
(3) first tensioning equipment of prefabricated tensioning equipment and second tensioning equipment are anchored at the concrete box web respectively up and down on the edge, and making that the bayonet lock in first tensioning equipment is vertical corresponding with hand winch in second tensioning equipment, the two with determined each the root stone dead wire of step (2) is respectively on the bayonet lock and the hand winch on half tensioning equipment that is connected on first tensioning equipment then;
The described tensioning equipment of this step is made up of first tensioning equipment and second tensioning equipment, wherein, first tensioning equipment is to constitute according to vertically arrange on the upper substrate bayonet lock of anchoring mild steel tow of the arrangement pitch of the determined mild steel tow of step (2), second tensioning equipment is to constitute according to the arrangement pitch of the determined mild steel tow of step (2) hand winch of vertically arranging on infrabasal plate, and wherein said hand winch wears the reel with crank by bearing pin and constitutes;
(4) shake crank on described second tensioning equipment, each root mild steel tow of stretch-draw one by one, and use the stress-strain test instrument to monitor the true vertical stress increment of web synchronously, when the detected value of stress-strain test instrument during, insert snib and fix second tensioning equipment more than or equal to the calculated value of 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.
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, elongation with steel ruler monitoring mild steel tow, make the actual elongation of each root mild steel tow more than or equal to calculated value, so that utilize the measurement of mild steel tow elongation to come verification stretch-draw effect, the stretch-draw of guaranteeing the mild steel tow reach expection case web stress improve target.
Above-mentioned method with steel ruler measurement mild steel tow elongation can adopt method commonly used in the engineering, specifically be, mild steel tow before the stretch-draw between first tensioning equipment and second tensioning equipment is done a mark, on the case web of this mark equal-height position, do a fixation mark again, mark on the mild steel tow that steel ruler monitored in the stretching process is the elongation that is tagged to mild steel tow between first tensioning equipment on the mild steel tow before the stretch-draw with respect to the distance between the fixation mark on the case web, can further be calculated the elongation of the mild steel tow between first tensioning equipment and second tensioning equipment by this elongation.
The theoretical elongation of the mild steel tow described in the said method can adopt following formula (III) to calculate
(III) in the formula, δ is the theoretical elongation of mild steel tow, and L is the length of mild steel tow, and E is the modulus of elasticity of mild steel tow, σ
nBe the control tension stress of mild steel tow, general press " standard " is taken as 1000MPa.
Method of the present invention, the wherein described vertical stress loss of step (2) sum Δ σ
Y1Equal ground tackle (comprising first tensioning equipment, second tensioning equipment and anchoring piece) loss
Mild steel tow relaxation loss
The elastic compression loss
Sum accounts for vertical stress increment desired value [Δ σ
y] 15%, so the detected value of stress-strain test instrument should be more than or equal to 115% 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 invention still further relates to the tensioning equipment of implementing said method, this tensioning equipment is made up of first tensioning equipment and second tensioning equipment, wherein, first tensioning equipment constitutes according to vertically arrange on the upper substrate bayonet lock of anchoring mild steel tow of the arrangement pitch of the determined mild steel tow of step (2) of said method, all is arranged with anchor hole on the upper substrate of each bayonet lock both sides; Second tensioning equipment constitutes according to the arrangement pitch of the determined mild steel tow of step (2) of the said method hand winch of vertically arranging on infrabasal plate, all be arranged with down anchor hole on the infrabasal plate of each hand winch both sides, wherein said hand winch wears the reel with crank by bearing pin and constitutes.Tensioning equipment of the present invention, wherein, described bayonet lock can be the various ground tackles or the similar item of anchoring steel strand, the crank that reel had of described hand winch, can be the one-armed crank of one-handed performance, also can be the cross crank of being convenient to bimanualness.
In the inventive method, 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 stretch-draw mild steel tow, 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. 9～10 are the process structure schematic diagram of the inventive method implementation process, and wherein, Fig. 9 is the schematic cross section of the concrete box web of a kind of concrete bridge of employing the inventive method reinforcing, demonstrates the installment state of described tensioning equipment among the figure; Figure 10 is the vertical section schematic diagram of the concrete box web of a kind of concrete bridge of adopting the inventive method and reinforcing, demonstrate among the figure distribution situation of mild steel tow and up and down tensioning equipment in concrete box web fixed form.
Figure 11～12 are the structural representation of a kind of specific embodiment (one-armed crank) of second tensioning equipment of tensioning equipment of the present invention, and wherein Figure 11 is a front view, Figure 12 vertical view (analysing and observe).
Figure 13～14 are the structural representation of the another kind of specific embodiment (cross crank) of second tensioning equipment of tensioning equipment of the present invention, and wherein Figure 13 is a front view, Figure 14 vertical view (analysing and observe).
Figure 15～16 are a kind of structural representation of specific embodiment of first tensioning equipment of tensioning equipment of the present invention, and wherein Figure 15 is a front view, Figure 16 vertical view (analysing and observe).
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 the three-dimensional coordinate of this bridge control node, generate the control node according to this bridge real size and detail structure; 2. loop control node, 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.The division of unit, as far as possible evenly reasonable, and fully reflect 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.
| 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 the stone dead wire specification of forming the mild steel tow.In this example, the mild steel tow adopts the galvanized mild steel silk of 15 1 bundles, the area of mild steel tow, control stress for prestressing σ
n, elastic modulus E is by " standard " value.
Secondly, draft the layout scope and the arrangement pitch D of mild steel tow.In this example, mild steel tow layout scope is for to locate from theoretical fulcrum 5m to 20m, and arrangement pitch, is partly striden monolateral layout and arranged 31 bundle mild steel tow when arrangement pitch D=0.5m by waiting 0.5m, 1.0m to carry out tentative calculation.
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 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 mild steel tow of preamble, import the node coordinate of mild steel tow, circulation generates all stone dead wire end node and unit; 6. with the node coupling of corresponding node of concrete web and mild steel tow, 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, the mild steel tow adopts the Link8 bar unit to divide simulation, mild steel tow 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. the mild steel tow is applied initial strain, the masterpiece that the stretch-draw of above-mentioned mild steel tow 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 mild steel tow arrangement pitch D is 0.5m, can make web vertical stress increment Δ σ by stretch-draw mild steel tow
YcReach 2.51～3.79MPa, deduct about 15%[Δ σ
y] loss of prestress, 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 apparent in view.When Fig. 7 is mild steel tow arrangement pitch D=0.5m, 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, the mild steel tow adopts 15 1 galvanized mild steel silk, and mild steel tow layout scope is in the scope of theoretical fulcrum 5m to 20m, and mild steel tow arrangement pitch D gets 0.5m, and full-bridge is arranged 2 * 8 * 31=496 bundle stone dead wire altogether.
C. prefabricated tensioning equipment.According to the specification and the arrangement pitch of the determined mild steel tow 4 of step b, prefabricated mild steel tow tensioning equipment.Described mild steel tow tensioning equipment is made up of first tensioning equipment 2 and second tensioning equipment 2 '.
Referring to Figure 15 and 16, first tensioning equipment 2 is to wear bayonet lock to constitute on upper substrate 2-1, and wherein said bayonet lock is that a sheathed steel strand anchorage drum 2-3 is clamped on the substrate 2-1 with nut 2-5 and constitutes on a pin 2-2 who is welded on the substrate 2-1.The above-mentioned pin 2-2 space D of the described mild steel tow of b set by step vertically is distributed on the upper substrate 2-1, is arranged with anchor hole 2-4 on the upper substrate 2-1 of each pin 2-2 both sides.
Referring to Figure 11 and 12 or Figure 13 and 14, second tensioning equipment 2 ' is that hand winch constitutes on infrabasal plate 2 '-1, wherein said hand winch is similar to the hoist engine that the edge rotates, and it is to use nut 2 '-5 barrier to constitute between infrabasal plate 2 '-1 again at the reel 2 '-3 that bearing pin 2 '-2 upper sleeve through one that is welded on the infrabasal plate 2 '-1 has crank 2 '-4.The above-mentioned hand winch space D of the described mild steel tow 4 of b set by step vertically is distributed on the infrabasal plate 2 '-1, is arranged with down anchor hole 2 '-6 on the substrate 2 '-1 of each bearing pin 2 '-2 both sides.
Crank 2 '-4th shown in Figure 11 and 12, the one-armed crank of common one-handed performance, crank 2 '-4th shown in Figure 13 and 14, the common cross crank of being convenient to bimanualness can be selected according to the needs of operation when specifically constructing.
D. be to connect the mild steel tow.In the following anchor hole 2 '-6 of the last anchor hole 2-4 of first tensioning equipment 2 and second tensioning equipment 2 ', penetrate expansion bolt 3, half tensioning equipment 2 and 2 ' that step c is made in advance is separately fixed at the last lower limb of case web 1 earlier, is respectively to connect the determined mild steel tow 4 of step b (seeing Fig. 9 and 10) then on the reel 2 '-3 of each steel strand anchorage drum 2-3 and pairing hand winch.
E. stretching construction.Shake the crank 2 '-4 of described hand winch and strain each root mild steel tow 4 (referring to Fig. 9 and 10) one by one, and adopt the true vertical stress increment of stress-strain test instrument monitoring case web 1, two index monitoring modes of employing steel ruler monitoring mild steel tow 4 elongations synchronously, produce a desired effect with the stretch-draw of guaranteeing mild steel tow 4.Wherein the method with steel ruler monitoring mild steel tow 4 elongations is: paint earlier on mild steel tow 4 and draw mark, paint again and on the case web 1 of this mark equal-height position, do a fixation mark, mark on the mild steel tow 4 that steel ruler monitored in the stretching process is the elongation that is tagged to mild steel tow 4 between first tensioning equipment 2 on the mild steel tow 4 before the stretch-draw with respect to the distance between the fixation mark on the case web 1, can further be calculated the elongation of the mild steel tow 4 between first tensioning equipment 2 and second tensioning equipment 2 ' by this elongation.
In this example, calculate to such an extent that the calculated value of the theoretical elongation that produces of each mild steel tow stretch-draw sees Table 2 according to formula described in the summary of the invention (III), when the actual elongation that records each root mild steel tow 4 with steel ruler during more than or equal to the calculated value in the table 2, promptly meet the requirements, otherwise should replenish stretch-draw.In this example, after all 4 stretch-draw of mild steel tow are finished, the vertical stress increment that case web 1 produces is 2.14～3.22MPa (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 theoretical elongation of table 2 mild steel tow
F. 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 (7)
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 the normal operational phase of concrete box-beam bridge 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 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
XvThe 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]
(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], the stone dead wire specification of mild steel tow, the radical and the arrangement pitch of mild steel tow are formed in preliminary election, allow stretching force to be applied to the correspondence position of plate shell finite element analytical model on the mild steel tow 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 is formed the specification of the stone dead wire of mild steel tow, the radical of mild steel tow and the spacing that the mild steel tow is evenly arranged and promptly is defined as actual reinforcing parameter, wherein Δ σ
Y1Be vertical prestressing loss sum in the stretching process;
(3) first tensioning equipment of prefabricated tensioning equipment and second tensioning equipment are anchored at the concrete box web respectively up and down on the edge, and making that the bayonet lock in first tensioning equipment is vertical corresponding with hand winch in second tensioning equipment, the two with determined each the root mild steel tow of step (2) is respectively on the bayonet lock and the hand winch on half tensioning equipment that is connected on first tensioning equipment then;
The described tensioning equipment of this step is made up of first tensioning equipment and second tensioning equipment, and wherein, first tensioning equipment is according to vertically arrange on the upper substrate bayonet lock formation of anchoring mild steel tow of the arrangement pitch of the determined mild steel tow of step (2); Second tensioning equipment is to constitute according to the arrangement pitch of the determined mild steel tow of step (2) hand winch of vertically arranging on infrabasal plate, and wherein said hand winch wears the reel with crank by bearing pin and constitutes;
(4) shake crank on described second tensioning equipment, each root mild steel tow of stretch-draw one by one, and use the stress-strain test instrument to monitor the true vertical stress increment of case web synchronously, when the detected value of stress-strain test instrument during, insert snib and fix second tensioning equipment more than or equal to the calculated value of 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.
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 the elongation of steel ruler monitoring mild steel tow, make the actual elongation of each root mild steel tow 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 115%.
5, a kind of tensioning equipment of implementing the described method of one of claim 1～4, this device is made up of first tensioning equipment and second tensioning equipment, wherein,
First tensioning equipment constitutes according to vertically arrange on the upper substrate bayonet lock of anchoring mild steel tow of the arrangement pitch of the determined mild steel tow of step (2) of claim 1, all is arranged with anchor hole on the upper substrate of each bayonet lock both sides;
Second tensioning equipment constitutes according to the arrangement pitch of the determined mild steel tow of step (2) of the said method hand winch of vertically arranging on infrabasal plate, all be arranged with down anchor hole on the infrabasal plate of each hand winch both sides, wherein said hand winch wears the reel with crank by bearing pin and constitutes.
6, tensioning equipment as claimed in claim 5 is characterized in that described bayonet lock is the various ground tackles or the similar item of anchoring steel strand.
7, tensioning equipment as claimed in claim 5 is characterized in that, the crank that described reel had is the one-armed crank of one-handed performance or the cross crank of being convenient to bimanualness.
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Effective date of registration: 20161213 Address after: 510380 Guangzhou City, Liwan District province flower road, South Road, No. 187, the construction of the 1 floor, No. Patentee after: Guangdong Rongjun construction engineering Limited by Share Ltd Address before: 510006 Guangdong City, Guangzhou Province University, West Ring Road, No. 230 Patentee before: Guangzhou Univ. |