Method for determining non-symmetrical closure gap state of steel truss bridge

Abstract

The application relates to a method for determining the asymmetric closure gap state of a steel truss bridge, which comprises the following steps: lowering the steel beam side support point elevation according to the maximum lowering height, and reserving a set gap between the side support point and the pier column; regarding the buckle tower and the buckle cable as a structural unit, sorting all the structural units, and composing a tension-compression strain energy vector U of the structural unit with respect to the axial force vector F N ; based on the initial axial force vector F N0 of the structural unit, the axial force influence matrix C of the buckle cable on the structural unit and the adjusting target value composed of the adjusting target value of the buckle cable force during the closure, obtaining the axial force vector F N ’ of the structural unit after the buckle cable is adjusted; based on the axial force vector F N ’ and the tension-compression strain energy vector U of the axial force vector F N , the tension-compression strain energy vector U' of the structural unit after the adjustment is calculated; taking the minimum tension-compression strain energy vector U' of the structural unit after the adjustment as the objective function, and based on the constraint condition, the adjusting target value T is calculated; and the buckle cable is tensioned according to the adjusting target value T to perform the closure.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of steel truss bridge construction, in particular to a method for determining the state of an asymmetric closure gap of a steel truss bridge. BACKGROUND

[0002] The closure of a steel truss bridge requires stress-free installation of members, and the elevation and angle of the cantilever end of the main beam need to meet the closure requirements.

[0003] For a steel truss bridge with a buckle cable and a buckle tower, a symmetric closure method is generally used to adjust the closure gap state by adjusting the cable force. At this time, the loads and structures on the left and right sides are symmetric, the deformations on the left and right sides are symmetric, and only one cantilever end vertical angle needs to be adjusted to 0 by trial calculation, and the other side uses the same adjustment scheme. According to the symmetry, the vertical deformations of the two ends of the member are the same, that is, the closure requirements can be met. The closure gap state of the symmetric structure is relatively easy to determine.

[0004] When the construction environment or construction scheme is limited, the closure gap can be set at the non-bridge center line, at which time the loads and structures on the left and right sides are asymmetric, and the structural deformations are also asymmetric. If the closure is controlled according to the principle that the vertical angle of the cantilever end of the closure gap is 0 and the vertical deformations of the members on both sides are the same, a larger cable force needs to be tensioned on one side of the large cantilever, which is not economical. At this time, the closure in the form of an angle is a closure method that is more in line with the stress and deformation, but the determination of the closure state needs to be calculated many times, and the difficulty of trial calculation is greater than that of symmetric closure. At the same time, due to the randomness of the trial calculation, the cable force calculated by the trial calculation may not be the optimal cable force, and the trial calculation target is not clear. SUMMARY

[0005] The present application provides a method for determining the state of an asymmetric closure gap of a steel truss bridge, which can solve the problem of large trial calculation difficulty and large randomness of the closure gap state in the asymmetric closure construction of a steel truss bridge in the related art.

[0006] The present application provides a method for determining the state of an asymmetric closure gap of a steel truss bridge, which includes:

[0007] Lower the steel beam side support point elevation by the maximum drop height, and reserve a gap between the steel beam side support point and the pier column;

[0008] Regarding the buckle tower and the buckle cable as a structural unit, sort all the structural units, and form a structural unit about the axial force vector F N tension-compression strain energy vector U ;

[0009] Based on the initial axial force vector F N0 of the structural unit, the cable force influence matrix of the structural unitC and a target value of the adjusting vector composed of the cable force adjustment target value of the closure cable T , the axial force vector of the structural unit after the cable adjustment F N ’ ;

[0010] based on the axial force vector of the structural unit after the cable adjustment F N ’ and the tension-compression strain energy vector related to the axial force vector F N U , the tension-compression strain energy vector of the structural unit after the cable adjustment U’ ;

[0011] taking the tension-compression strain energy vector of the structural unit after the cable adjustment U’ as the objective function and based on the constraint condition, the adjusting vector is calculated T ;

[0012] the closure cable is tensioned according to the adjusting vector T , so as to perform the closure.

[0013] In some embodiments, the constraint condition comprises that the axial forces of the top chord and the bottom chord at the closure gap are 0, and the forces of the top chord and the bottom chord in the cable area meet the specification requirements;

[0014] taking the tension-compression strain energy vector of the structural unit after the cable adjustment U’ as the objective function and based on the constraint condition, the adjusting vector is calculated T , specifically comprising:

[0015] based on the constraint condition that the axial forces of the top chord and the bottom chord at the closure gap are 0, and the forces of the top chord and the bottom chord in the cable area meet the specification requirements, taking the tension-compression strain energy vector of the structural unit after the cable adjustment U’ as the objective function, the adjusting vector is calculated by linear programming and optimization method T .

[0016] In some embodiments, the axial force specified value vector of the top chord and the bottom chord at the closure gap is P = , the initial axial force of the top chord and the bottom chord before the cable adjustment is P 0= ; the constraint condition that the axial forces of the top chord and the bottom chord at the closure gap are 0 is: P = P 0+ C K × T ;

[0017] wherein, C K = ; ​is the change in the axial force of the i-th unit of the upper and lower chords of the closure caused by the unit force applied by the j-th cable.

[0018] In some embodiments, the method further includes obtaining the constraint conditions when the upper and lower chord members in the cable zone meet the requirements of the specification. The specific steps include: based on the allowable axial force vector of the member under tension during the construction phase N max , allowable axial force vector of the member under compression N min and the axial force vectors of the upper and lower chords after cable adjustment N , obtain the constraint conditions when the forces on the upper and lower chord members in the cable-stayed area meet the requirements of the specification.

[0019] In some embodiments, the constraint conditions for the forces on the upper and lower chord members of the cable tie area to meet the requirements of the specification are: N min ≤ N ≤ N max ;

[0020] Based on the allowable axial force vector of the member under tension during the construction phase N max , allowable axial force vector of the member under compression N min and the axial force vectors of the upper and lower chords after cable adjustment N Before obtaining the constraint conditions that the upper and lower chord members in the cable zone meet the requirements of the specification, the method further includes obtaining the axial force vectors of the upper and lower chord members after the cable is adjusted. N Steps: Based on the axial force vectors of the upper and lower chords before adjusting the cables N 0 、 The influence matrix of each cable on the axial force of the upper and lower chords in the cable area C N and the adjustment vector composed of the target value of the cable force adjustment at the time of closure T , get the axial force vectors of the upper and lower chords after cable adjustment N ;in, N = N 0+ C N × T

[0021] In some embodiments, the buckle tower and the buckle cable are regarded as structural units, and all the structural units are sorted to form a structural unit about the axial force vector F N The tensile and compressive strain energy vector U , specifically including:

[0022] Establish structural elements about axial force F N The tensile and compressive strain energy function U;

[0023] Based on the structural element about the axial force FN the tensile and compressive strain energy function U and coefficient formula, obtaining the tensile and compressive strain energy calculation matrix of the structural unit U .

[0024] In some embodiments, ;

[0025] wherein m is the sum of the total number of structural units of the buckling cable and the buckling tower, is the unit length of the i-th unit, is the material elastic modulus of the i-th unit, is the cross-sectional area of the i-th unit, and F N,i is the unit axial force of the i-th unit.

[0026] In some embodiments, U = F N T × B × F N ;

[0027] wherein, F N = ;

[0028] , ;

[0029] wherein bii is the diagonal element of the coefficient matrix B.

[0030] In some embodiments, F N ’ = F N0 +C × T , wherein F N0 = , m=k+l, k is the sum of the number of units on the left and right sides of the closure opening, and l is the sum of the number of units on the left and right sides of the closure opening;

[0031] C = , wherein represents the change amount of the axial force of the i-th unit caused by the unit force of the j-th buckling cable, T = , is the to-be-determined adjusting cable force of the j-th buckling cable, 1

[0032] U' = C 0+ F N0 T × B ×C × T + T T × C T × B × F N0 + T T × C T × B × C × T ,

[0033] in, C0 = FN0T × B × FN0 , B is the coefficient matrix.

[0034] In some embodiments, the modulation vector is calculated T Before tensioning the cable, the method further comprises: erecting the steel truss to the joint;

[0035] According to the adjustment vector T When tensioning the cables, adjust the height of the side supports of the steel beam at the same time, and move the main beam longitudinally to meet the requirements of the joint.

[0036] The beneficial effects of the technical solutions provided in the embodiments of the present application include:

[0037] The embodiment of the present application provides a method for determining the asymmetric closure state of a steel truss bridge by ... F N The tensile and compressive strain energy vector U and constraints can quickly determine the adjustment vector that meets the closure requirements T， And according to the modulation vector T , tensioning the cables to close the steel truss bridge, solving the problem of repeated trial calculations required by traditional methods; adopting the method of minimizing the tensile and compressive strain energy to determine the cable force, which can minimize the use of cables and pylons while meeting the closure requirements; this application is not only applicable to the calculation of asymmetric closure of continuous steel truss bridges constructed with cables and pylons, but also can use the same constraints to calculate the asymmetric closure of steel truss cable-stayed bridges. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0039] Figure 1 A flow chart of a method for determining a non-symmetrical closure gap state of a steel truss bridge is provided in the embodiments of the present application.

[0040] Figure 2 A facade schematic diagram of a steel truss bridge in a construction stage is provided in the embodiments of the present application.

[0041] In the figure: 1, a buckle tower; 2, a buckle cable. DETAILED DESCRIPTION

[0042] In order to enable persons skilled in the art to better understand the schemes of the present application, the technical schemes in the embodiments of the present application will be described clearly and completely below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by persons skilled in the art without creative labor fall within the scope of protection of the present application.

[0043] The embodiments of the present application provide a method for determining a non-symmetrical closure gap state of a steel truss bridge, which can solve the problems of great difficulty in trial calculation and great randomness of the closure gap state in the non-symmetrical closure construction of a steel truss bridge in the related art.

[0044] The embodiments of the present application provide a method for determining a non-symmetrical closure gap state of a steel truss bridge, which includes:

[0045] 101: Lower the steel beam side support point elevation according to the maximum drop height, and reserve a set gap between the steel beam side support point and the pier column;

[0046] 102: Take the buckle tower 1 and the buckle cable 2 as a structural unit, sort all the structural units, and compose a structural unit about the axial force vector F ; N U ;

[0047] 103: Obtain the axial force vector of the structural unit after adjustment of the cable based on the initial axial force vector F N0 of the structural unit, the axial force influence matrix of the cable 2 cable force on the structural unit C , and the adjustment vector composed of the adjustment target value of the cable 2 cable force during closure T ; F N ’ ;

[0048] 104: Obtain the axial force vector of the structural unit after adjustment of the cable based on the axial force vector of the structural unit after adjustment of the cable F N ’ ; FN tension-compression strain energy vector of the structural unit U , calculate the tension-compression strain energy vector of the structural unit after adjusting the cable U’ ;

[0049] 105: tension-compression strain energy vector of the structural unit after adjusting the cable U’ , calculate the adjustment vector based on the constraint condition T ;

[0050] 106: tension the cable 2 according to the adjustment vector T , and close the gap.

[0051] When the construction environment or construction scheme is limited, the closure gap can be set at the non-bridge center line, and the load and structure on the left and right sides are asymmetric, and the structural deformation is also asymmetric. In this application, the tension-compression strain energy vector of the structural unit about the axial force vector F N tension-compression strain energy vector of the structural unit U and the constraint condition can quickly determine the adjustment vector that meets the closure requirement T , and according to the adjustment vector T , the cable 2 is tensioned to close the gap of the steel truss bridge, which solves the problem of repeated trial calculation in the traditional method; using the method of minimizing the tension-compression strain energy, that is, the tension-compression strain energy vector of the structural unit after adjusting the cable U’ , the target function is determined to minimize the use of cable 2 and cable tower 1 while meeting the closure requirement; this application not only applies to the asymmetric closure calculation of continuous steel truss bridges using cable 2 and cable tower 1 for construction, but also can be calculated using the same constraint condition for asymmetric closure of steel truss cable-stayed bridges.

[0052] In step 101: the steel beam edge support point elevation is lowered by the maximum drop height, and a certain gap is reserved between the steel beam edge support point and the pier column. First, determine the maximum drop height of the steel beam edge support point according to the height of the abutment and the support at the side pier, then lower the steel beam edge support point elevation by the maximum drop height, so as to reduce the deflection and angle of the cantilever end of the main beam as much as possible. Further, considering the complexity of the actual construction situation, a certain gap needs to be reserved between the steel beam edge support point and the pier column when the steel beam edge support point is lowered, that is, a certain surplus value is left to fine-tune the closure gap on site.

[0053] On the basis of the above embodiment, in this embodiment, the cable tower 1 and the cable 2 are regarded as structural units, all the structural units are sorted, and the tension-compression strain energy vector of the structural unit about the axial force vector F N tension-compression strain energy vector of the structural unit U , specifically comprising steps 1021 to 1022:

[0054] Step 1021: Establish the tensile and compressive strain energy function U of the structural unit with respect to the axial force F. N .

[0055] First of all, it needs to be pointed out that in the present embodiment, one buckle tower unit and one buckle unit constitute a structural unit; wherein one buckle cable 2 is a buckle unit, and one buckle tower 1 can be divided into multiple buckle tower units: in some embodiments, the part between the two buckle cable 2 connection points on one buckle tower 1 can be set as a buckle tower unit, such as Figure 2 The area shown in b in FIG. 1 is a buckle tower unit, A is the center line of symmetry of the steel truss bridge, and a is the closure opening; the section of the buckle tower 1 without the buckle cable 2 can be freely divided into buckle tower units. After determining the buckle tower units and the buckle units, multiple structural units composed of them are sorted for subsequent differentiation and calculation.

[0056] The formula for calculating the tensile and compressive strain energy function U is:

[0057]

[0058] Wherein m is the sum of the total number of structural units of the buckle cable 2 and the buckle tower 1, is the unit length of the i-th unit, is the material elastic modulus of the i-th unit, is the cross-sectional area of the i-th unit, and F N,i is the unit axial force of the i-th unit.

[0059] Step 1022: Based on the tensile and compressive strain energy function U of the structural unit with respect to the axial force F N and the coefficient formula, obtain the tensile and compressive strain energy calculation matrix U of the structural unit.

[0060] Specifically, the tensile and compressive strain energy function U of the structural unit with respect to the axial force F N here is the tensile and compressive strain energy function U mentioned above , and the coefficient formula is ;

[0061] The coefficient formula is brought into the tensile and compressive strain energy function U to obtain the tensile and compressive strain energy calculation matrix U of the structural unit, and U = F N T × B × F N ;

[0062] In U = F N T × B × F N , FN = ;

[0063] , (i = 1, 2,..., m);

[0064] Here, bii is the diagonal element of the coefficient matrix B.

[0065] On the basis of the above-mentioned embodiment, in the present embodiment, step 103: based on the initial axial force vector of the structural unit F N0 , the axial force influence matrix of the structural unit by the cable force of the cable 2 C and the adjusting vector composed of the adjusting target value of the cable force of the cable 2 during closure T , the axial force vector of the structural unit after adjusting the cable is obtained F N ’ Among them, specifically:

[0066] Let the initial axial force vector of the structural unit before adjusting the cable be F N0 , the adjusting vector composed of the adjusting target value of the cable force of the cable 2 during closure be T , then the axial force vector of the structural unit after adjusting the cable is F N ’ :

[0067] F N ’ = F N0 +C × T ;

[0068] Among them F N0 = , m = k + l, k is the sum of the number of cable units on the left and right sides of the closure, and l is the sum of the number of cable units on the left and right sides of the closure, C = Among them represents the change amount of the axial force of the i-th unit caused by the unit force of the j-th cable 2, is a known quantity, j is 1~l in the axial force influence matrix of the structural unit by the cable force of the cable 2 C ;

[0069] T = , is the to-be-determined adjusting cable force of the j-th cable 2, 1 < j < l, is an unknown quantity.

[0070] The axial force vector of the structure unit after the cable adjustment determined in this step F N ’ The function of the unknown quantity about the cable adjustment force .

[0071] On the basis of the above-mentioned embodiments, in this embodiment, step 104: based on the axial force vector of the structure unit after the cable adjustment F N ’ And the tension-compression strain energy vector about the axial force vector F N U , calculate the tension-compression strain energy vector of the structure unit after the cable adjustment U’ In particular:

[0072] The axial force vector of the structure unit after the cable adjustment F N ’ = F N0 +C × T Into the tension-compression strain energy vector about the axial force vector F N U = F N T × B × F N , get the tension-compression strain energy vector of the structure unit after the cable adjustment U’ :

[0073]

[0074] That is U' = C 0+ F N0 T × B × C × T + T T × C T × B × F N0 + T T × C T × B × C × T ,

[0075] Among them, C0 = FN0T × B ×​​FN0 , B is the coefficient matrix, in which, C0 、 B 、 C 、 FN0 and the coefficient matrix are known quantities, T To be sought quantity.

[0076] Based on the above embodiment, in this embodiment, step 105: using the tension and compression strain energy vector after the structural unit is adjusted U’ Minimum is the objective function, and based on the constraints, the adjustment vector is calculated T In particular:

[0077] The constraint conditions include: the axial force of the upper and lower chords at the closure is 0, and the forces on the upper and lower chords in the cable-stayed area meet the requirements of the specification. It should be noted that the cable-stayed area refers to the area from the anchor point of the cable 2 on the bridge to the cable tower 1.

[0078] Tensile and compressive strain energy vector after adjusting the cable with structural elements U’ Minimum is the objective function, and based on the constraints, the adjustment vector is calculated T Specifically include:

[0079] Based on the constraint conditions that the axial force of the upper and lower chords at the closure is 0 and the forces on the upper and lower chords in the cable-stayed area meet the requirements of the specification, the tensile and compressive strain energy vector after the structural unit is adjusted is used. U’ Minimum is the objective function, and the adjustment vector is calculated through linear programming and optimization methods. T。

[0080] In this embodiment, the structural unit is about the axial force vector F N The tensile and compressive strain energy vector U and constraints can quickly determine the adjustment vector that meets the closure requirements T， And according to the modulation vector T , tensioning the cable 2 to close the steel truss bridge, solving the problem of repeated trial and error in traditional methods. And the method of minimizing the tensile and compressive strain energy is adopted, that is, the tensile and compressive strain energy vector after the structural unit cable is adjusted is used. U’ The objective function is to determine the minimum cable force in cable 2 while minimizing the number of cables and pylons used while meeting the closure requirements. This method is not only applicable to the calculation of asymmetric closures of continuous steel truss bridges constructed using cable 2 and pylons, but can also be used to calculate asymmetric closures of steel truss cable-stayed bridges using the same constraints.

[0081] When the steel truss reaches the ideal closure state, the axial forces of the upper and lower chords at the closure gap should be 0, and the forces of the upper and lower chords in the buckle cable area should meet the requirements of the specification, and the minimum tensile and compressive strain energy values should be obtained. The axial forces of the upper and lower chords are generally adjusted to 0, and the axial forces of the inclined rods are automatically 0, so the axial forces of the inclined rods do not need to be set as constraint conditions. Since the forces of the cantilever end rods are only affected by the self weight and not affected by the adjustment cable, the forces of these rods do not need to be set as constraint conditions.

[0082] In the constraint condition that the axial forces of the upper and lower chords at the closure gap are 0:

[0083] Let the axial force specified value vector of the upper and lower chords at the closure gap be P = , the initial axial force of the upper and lower chords before adjustment of the cable be P 0= , and the adjustment vector composed of the adjustment target values of the cable 2 forces at the closure be T ; then the constraint condition that the axial forces of the upper and lower chords at the closure gap are 0 is:

[0084] P = P 0+ C K × T ;

[0085] wherein C K = ;

[0086] C K is the influence matrix of each cable 2 on the axial forces of the upper and lower chords at the closure gap, and a ij is the change amount of the axial force of the i th unit of the upper and lower chords at the closure gap caused by the unit force of the j th cable 2, which is a known quantity.

[0087] In the constraint condition that the forces of the upper and lower chords in the buckle cable area meet the requirements of the specification:

[0088] First, the axial force vector of the upper and lower chords after adjustment of the cable is obtained based on the axial force vector of the upper and lower chords before adjustment of the cable N 0 N , the influence matrix of each cable 2 on the axial forces of the upper and lower chords in the buckle cable area 、 N , and the adjustment vector composed of the adjustment target values of the cable 2 forces at the closure C : T N : N = N 0+ C N × T

[0089] ​Then based on the construction stage bar member tension allowable axial force vector N max , bar member compression allowable axial force vector N min and the adjusted chord bar axial force vector N , the constraint condition when the chord bar member force in the cable zone meets the specification requirements is obtained.

[0090] Wherein, the bar member size has been determined in the bridge completion calculation, the bar member size here is the size of the main girder bar member, which has been determined in the design stage; assuming that the total number of chord bar members in the cable zone is n, the construction stage bar member tension allowable axial force vector N max : N max and the bar member compression allowable axial force vector N min : N min It should be noted that the bar member axial force calculation is stipulated to be positive when the bar member is in tension and negative when the bar member is in compression.

[0091] Then the constraint condition when the chord bar member force in the cable zone meets the specification requirements is: N min ≤ N ≤ N max ;

[0092] After obtaining the constraint condition P = P 0+ C K × T and N min ≤ N ≤ N max , it is combined with the tension and compression strain energy vector of the structure unit after adjusting the cable U' = C 0+ F N0 T × B × C × T + T T × C T × B × F N0 + T T × C T × B × C ×T the tensile and compressive strain energy vectors of the structural unit after adjusting the cable force U’ The minimum value of the tensile and compressive strain energy vectors of the structural unit after adjusting the cable force T The optimal cable force of each cable 2 under tension can be obtained.

[0093] In the above embodiment, the calculated adjusting vector is used to adjust the cable force of the cable 2. T Before tensioning the cable 2, the method further comprises erecting the steel truss at the closure gap, and simultaneously adjusting the cable force of the cable 2 according to the adjusting vector T When tensioning the cable 2, the height of the side support point of the steel beam is adjusted, and the longitudinal displacement of the main beam is adjusted to meet the closure requirement, and then the closure is performed.

[0094] In summary, the present application solves the problems of the traditional method, such as repeated trial calculation, low efficiency, and randomness of the trial cable force, and the tensile and compressive strain energy vectors of the structural unit after adjusting the cable force U’ and the constraint condition can quickly determine the optimal cable force that meets the closure requirement; since the tensile and compressive strain energy of the cable tower 1 and the cable 2 is minimized, the use amount of the cable 2 and the cable tower 1 can be minimized by using the cable force determined by the present application; at the same time, the present application is not only applicable to the asymmetric closure calculation of the continuous steel truss bridge using the cable 2 and the cable tower 1 for construction, but also applicable to the asymmetric closure calculation of the steel truss cable-stayed bridge using the same constraint condition.

[0095] In the description of the present application, it should be noted that the orientation or position relationship indicated by the terms "upper", "lower", etc. is based on the orientation or position relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. Unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection" should be understood broadly, for example, it can be fixed connection, or detachable connection, or integral connection; it can be mechanical connection, or electrical connection; it can be direct connection, or indirect connection through an intermediate medium, or internal communication of two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0096] It should be noted that, in the present application, the relational terms such as "first" and "second", and the like, are used solely to distinguish one entity or action from another, without necessarily requiring or implying any actual relationship or order between such entities or actions. Moreover, the terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can also include other elements not expressly listed or inherent to such process, method, article, or apparatus. An element proceeded by "comprises... a" does not, without more constraints, exclude the existence of additional identical elements in the process, method, article, or apparatus that comprises the element.

[0097] The foregoing is merely illustrative of the principles of the application and various modifications can be made by those skilled in the art without departing from the spirit and scope of the application. The above embodiments are illustrative, and not restrictive, of the scope of the application.

Claims

1. A method for determining the asymmetric closure state of a steel truss bridge, characterized in that: It includes: Lower the elevation of the steel beam side support point according to the maximum drop height, and reserve a set gap between it and the pier column; Consider the buckle tower (1) and the buckle cable (2) as structural units, sort all the structural units, and form the structural units about the axial force vector F N The tensile and compressive strain energy vector U ; Initial axial force vector based on structural elements F N0 、 Cable (2) Cable force influence matrix on the axial force of structural unit C and the adjustment vector composed of the target value of the cable force adjustment of the cable (2) at the time of closure T , obtain the axial force vector of the structural unit after cable adjustment F N ’ ; Based on the axial force vector after cable adjustment F N ’ and the force vector about the axis F N The tensile and compressive strain energy vector U , calculate the tensile and compressive strain energy vector of the structural unit after cable adjustment U’ ; Tensile and compressive strain energy vector after adjusting the cable with structural elements U’ Minimum is the objective function, and based on the constraints, the adjustment vector is calculated T ; According to the adjustment vector T , tension the cable (2) to close the joint.

2. The method for determining the asymmetric closure state of a steel truss bridge according to claim 1, wherein: The constraint conditions include: the axial force of the upper and lower chords at the closure is 0, and the forces on the upper and lower chords in the cable-stayed area meet the requirements of the specification; Tensile and compressive strain energy vector after adjusting the cable with structural elements U’ Minimum is the objective function, and based on the constraints, the adjustment vector is calculated T , specifically including: Based on the constraint conditions that the axial force of the upper and lower chords at the closure is 0 and the forces on the upper and lower chords in the cable-stayed area meet the requirements of the specification, the tensile and compressive strain energy vector after the structural unit is adjusted is used. U’ Minimum is the objective function, and the adjustment vector is calculated through linear programming and optimization methods. T .

3. The method for determining the asymmetric closure state of a steel truss bridge according to claim 2, characterized in that: Let the axial force specified value vector of the upper and lower chords at the closure be P = , the initial axial force of the upper and lower chords before adjusting the cables is P 0= ; The constraint condition for the axial force of the upper and lower chords at the closure to be 0 is: P=P 0+ C K × T ； in, C K = ; is the change in the axial force of the i-th unit of the upper and lower chords of the closure caused by the unit force applied by the j-th cable (2).

4. The method for determining the asymmetric closure state of a steel truss bridge according to claim 2, wherein: The method further includes obtaining constraint conditions when the forces on the upper and lower chord members in the cable-stayed area meet the requirements of the specification, and the specific steps include: Based on the allowable axial force vector of the member under tension during the construction phase N max , allowable axial force vector of the member under compression N min and the axial force vectors of the upper and lower chords after cable adjustment N , obtain the constraint conditions when the forces on the upper and lower chord members in the cable-stayed area meet the requirements of the specification.

5. The method for determining the asymmetric closure state of a steel truss bridge according to claim 4, characterized in that: The constraint conditions for the upper and lower chord members in the cable zone to meet the requirements of the specification are: N min ≤ N ≤ N max ; Based on the allowable axial force vector of the member under tension during the construction phase N max , allowable axial force vector of the member under compression N min and the axial force vectors of the upper and lower chords after cable adjustment N Before obtaining the constraint conditions that the upper and lower chord members in the cable zone meet the requirements of the specification, the method further includes obtaining the axial force vectors of the upper and lower chord members after the cable is adjusted. N Steps: Based on the axial force vector of the upper and lower chords before cable adjustment N 0 、 The influence matrix of each cable (2) on the axial force of the upper and lower chords in the cable area C N and the adjustment vector composed of the target value of the cable force adjustment of the cable (2) at the time of closure T , get the axial force vectors of the upper and lower chords after cable adjustment N ; in, N = N 0+ C N × T .

6. The method for determining the asymmetric closure state of a steel truss bridge according to claim 1, wherein: Consider the buckle tower (1) and the buckle cable (2) as structural units, sort all the structural units, and form the structural units with respect to the axial force vector. F N The tensile and compressive strain energy vector U , specifically including: Establish structural elements about axial force F N The tensile and compressive strain energy function U; Based on the structural element about the axial force F N The tensile and compressive strain energy function U and coefficient formula are used to obtain the tensile and compressive strain energy calculation matrix of the structural unit. U .

7. The method for determining the asymmetric closure state of a steel truss bridge according to claim 6, characterized in that: ； Where m is the sum of the total number of structural units of the cable (2) and the tower (1), is the unit length of unit i, is the material elastic modulus of unit i, is the cross-sectional area of ​​unit i, F N,i is the unit axial force of unit i.

8. The method for determining the asymmetric closure state of a steel truss bridge according to claim 7, characterized in that: U=F N T × B × F N ； in, F N = ; , (i=1、2、...、m); Where bii is the diagonal element of the coefficient matrix B.

9. The method for determining the asymmetric closure state of a steel truss bridge according to claim 1, wherein: F N ’ = F N0 +C × T ,in F N0 = , m=k+l, k is the sum of the number of buckle tower units on the left and right sides of the closure, l is the sum of the number of buckle cable units on the left and right sides of the closure; C = ,in represents the change in the axial force of the i-th unit caused by the unit force applied by the j-th cable (2), T = , is the to-be-determined adjustment force of the j-th cable (2), 1<j<l; U'=C 0+ F N0 T × B × C × T + T T × C T × B × F N0 + T T × C T × B × C × T ， in, C0 = FN0T × B × FN0 , B is the coefficient matrix.

10. The method for determining the asymmetric closure state of a steel truss bridge according to claim 1, wherein: According to the calculated modulation vector T Before tensioning the cable (2), the method further comprises: erecting the steel truss to the joint; According to the adjustment vector T When tensioning the cable (2), the height of the side support of the steel beam is adjusted at the same time, and the main beam is moved longitudinally to meet the requirements of the joint.

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