CN114117621A - Method for determining optimal reasonable bridge forming state of deck type beam-arch combined rigid frame bridge - Google Patents

Abstract

The invention discloses a method for determining the optimal reasonable bridge forming state of a through-put type beam-arch combined rigid frame bridge, which can efficiently and accurately find the optimal reasonable bridge forming stress state and the optimal reasonable bridge forming line shape of the through-put type beam-arch combined rigid frame bridge by controlling the bridge forming state of the whole structure system according to key points; by establishing a beam-arch combined rigid frame bridge finite element model, accurately simulating the stress state in the construction stage, and applying a normal installation iteration method to carry out calculation and analysis, judging whether the key strength technical parameters and the key rigidity technical parameters of the upper deck beam-arch combined rigid frame bridge meet the target limit value, accurately determining the most reasonable mid-span ratio of a main beam, the mid-span ratio of a lower chord arch and the arch axis line shape, determining the beam height value with the optimal key section, greatly increasing the utilization rate of materials, improving the economy of engineering and saving a large amount of investment cost; the method has clear thought, strong applicability and great popularization value.

Description

Method for determining optimal reasonable bridge forming state of deck type beam-arch combined rigid frame bridge

Technical Field

The invention relates to a method for determining the optimal reasonable bridge forming state of a through beam-arch combined rigid frame bridge.

Background

China is a country with multiple mountainous areas, the mountainous areas occupy 2/3 of the area of national soil, and when the main span of a bridge crossing rivers and valleys in the mountainous areas exceeds 200m, the traditional prestressed concrete continuous rigid frame bridge is not suitable due to the common defects of midspan downwarping, box girder web cracking and the like.

The deck type beam-arch combined rigid frame bridge is a novel combined bridge which combines a prestressed concrete continuous rigid frame and a deck type arch to form a self-balancing thrust-free stress system, improves the defects of midspan downwarping and web cracking, improves the structural rigidity and realizes larger spanning capacity, and the bridge fully integrates the advantages of bending of the beam bridge and compression of the arch bridge and develops the span of the bridge to 350-400 m. The bridge is generally constructed by adopting an upper chord beam and a lower chord arch double-layer temporary inclined pulling buckle cantilever hanging method, has low requirements on machine tool sites and transportation conditions, and has strong adaptability to mountain areas with high mountains, steep slopes and narrow construction sites.

The upper structure of the upper bearing type beam-arch combined rigid frame bridge comprises an upper chord beam, a lower chord arch, a beam-arch joint section, a pier-beam joint section, a pier-arch joint section, a conventional beam section and the like, wherein force transmission lines of the conventional beam section, the upper chord beam and the lower chord arch are changed at joint parts, and a joint transition section is required to be designed for ensuring smooth force transmission; the construction process of the beam-arch combined rigid frame bridge integrates the construction processes of a beam bridge, a suspension casting arch bridge and a short-tower cable-stayed bridge, and needs to undergo multiple system conversion, and the novel combined structure system is constructed by synchronously obliquely pulling and buckling an upper chord box girder and a lower chord arch girder in the bridge construction process, and has the difficulties of large construction state change, more system conversion, complex construction process, high construction control requirement and the like.

The deck type beam-arch combined rigid frame bridge is used as a novel combined bridge, the existing domestic design cases are few, the research on the structural system and the mechanical behavior of the beam-arch combined rigid frame bridge is not deep enough, and particularly, the research result on the reasonable bridge forming state of the beam-arch combined rigid frame bridge is less. The beam-arch combined rigid frame bridge designed at present has the following problems: the upper chord beam, the lower chord arch and the span-middle section have unreasonable beam heights, so that the material utilization rate is low, the engineering economy is poor, the rise-span ratio and the arch axis line shape of the lower chord arch are unreasonable, the advantage of 'compression' of the lower chord arch is difficult to be fully exerted in a structural system, and the bridge-forming state mechanical property of the structural system is poor due to the unreasonable arrangement of the span-middle ratio of the 3 main beam.

Disclosure of Invention

The invention aims to provide a method for determining the optimal reasonable bridge forming state of a through-type beam-arch combined rigid frame bridge, and aims to solve the problems of low material utilization rate, poor engineering economy, unreasonable stress of a structural system and poor main beam line shape in the bridge forming state caused by the defects of the structural system and the mechanical behavior research of the through-type beam-arch combined rigid frame bridge at present.

In order to solve the technical problem, the invention provides a method for determining the optimal reasonable bridge forming state of a through beam-arch combined rigid frame bridge, which comprises the following steps:

s1: determining an invariant and a variable of the deck beam-arch combined rigid frame bridge according to the characteristics of a deck beam-arch combined rigid frame bridge structure system, drawing up a reasonable value range of the variable, and setting an initial value, a step length and a final value;

s2: determining a key control point in a reasonable bridge forming state according to the characteristics of a structural system of the upper bearing type beam-arch combined rigid frame bridge, and determining a judgment index in the reasonable bridge forming state and a target limit value of the judgment index according to the key control point;

s3: establishing a finite element analysis model according to the invariants and the variables of the deck beam-arch combined rigid frame bridge; carrying out stress analysis on the structural system of the upper-bearing beam-arch combined rigid frame bridge according to the finite element analysis model, judging whether the calculated judgment index meets the target limit value of the judgment index, and if so, obtaining the optimal value meeting the optimal reasonable variable quantity of the formed bridge state; otherwise, continuously iterating and optimizing the variable quantity through the finite element model to obtain the optimal value which is finally converged into the optimal solution and used as the optimal value of the optimal reasonable bridge-forming state variable quantity;

s4: and carrying out structural design according to the optimal value of the optimal reasonable bridging state variable quantity to obtain the optimal reasonable bridging state of the deck type beam-arch combined rigid frame bridge.

Further, according to the characteristics of the structural system of the upper-bearing beam-arch combined rigid frame bridge, the invariants of the upper-bearing beam-arch combined rigid frame bridge comprise a main span L and a main pier height H.

Further, according to the characteristics of the structural system of the deck beam-arch combined rigid frame bridge, the variable quantity of the deck beam-arch combined rigid frame bridge comprises the following steps: side-to-middle span ratio, lower chord arch rise f and triangular space span L_sArch axis line shape, lower chord arch beam height h₁Height h of upper chord arch standard beam₂Main span middle beam height h₃The height h of the upper chord beam root beam₄。

And further, when the stress analysis of the structural system of the upper-bearing beam-arch combined rigid frame bridge is carried out according to the finite element analysis model, the stress influence degrees of the structural system of the upper-bearing beam-arch combined rigid frame bridge are subjected to importance grading sequencing according to variable quantities, and iterative computation analysis is carried out according to the influence degree sequence of the variable quantities.

Further, the key control points comprise a pier-beam fixing point A, a beam-arch joint point B, a mid-span mid-point C, a pier-arch fixing point D and a main pier bottom point E.

Further, the judgment index of the reasonable bridging state comprises a key strength parameter; the key intensity parameters include: bending moment ratio M of beam arch joint point and pier beam fixing point_B/M_AShear force ratio Qs of beam arch joint point and pier beam fixed joint point_B/Qs_ABending moment ratio M of mid-span point and beam arch joint point_C/M_BAxial force ratio N between side span and mid-span side of pier arch consolidation point_{D side span}/N_{D midspan}Eccentric moment e of pier bottom of main pier_E＝M_E/N_EPositive and negative bending moment ratio M of lower chord arch_a+/M_a-Lower chord arch eccentricity e_a。

Further, the judgment index of the reasonable bridging state also comprises a key rigidity parameter; the key stiffness parameters include: road load lower bending span ratio omega₁/L, long-term shrinkage creep lower flex span ratio omega₂/L。

Further, the step S3 includes

S31: establishing a finite element analysis model according to the invariants and the variables of the deck beam-arch combined rigid frame bridge; carrying out stress analysis calculation on the structural system of the upper bearing type beam-arch combined rigid frame bridge according to the finite element analysis model to obtain a key strength parameter and a key rigidity parameter of the structural system of the upper bearing type beam-arch combined rigid frame bridge;

s32: judging whether the key strength parameter obtained by calculation in the step S31 meets the target limit of the key strength parameter, if so, obtaining the optimal value meeting the optimal reasonable bridge-forming state variable; otherwise, continuously performing iterative optimization calculation on the variable quantity through the finite element model according to the step length adjustment variable quantity to obtain the optimal value which is finally converged into the optimal solution and is used as the optimal value of the optimal reasonable bridge-forming state variable quantity;

s31: judging whether the key stiffness parameter obtained by calculation in the step S31 meets the target limit value of the key stiffness parameter, if so, obtaining the optimal value meeting the optimal reasonable bridge-forming state variable; and otherwise, continuously carrying out iterative optimization calculation on the variable quantity through the finite element model according to the step length adjustment variable quantity to obtain the optimal value which is finally converged into the optimal solution and is used as the optimal value of the optimal reasonable bridge-forming state variable quantity.

Further, the girder span-middle pushing is carried out before the main span-middle folding, so that the stress state of the main pier is improved.

Furthermore, the main beam and the lower chord arch are set into a bridge pre-arch degree by considering the influence of live load and shrinkage creep, and the construction pre-arch degree is set in the construction process.

The invention has the beneficial effects that: by controlling the bridging state of the whole structural system according to key points, the optimal reasonable bridging stress state and the optimal reasonable bridging line shape of the through-girder arch combined rigid frame bridge can be efficiently and accurately found; by establishing a beam-arch combined rigid frame bridge finite element model, accurately simulating the stress state in the construction stage, and applying a normal installation iteration method to carry out calculation and analysis, judging whether the key strength technical parameter and the key rigidity technical parameter of the upper bearing type beam-arch combined rigid frame bridge meet the target limit value or not, the method can accurately determine the most reasonable mid-span ratio of the main beam, the mid-span ratio of the lower chord arch and the arch axis line shape, determine the beam height value with the optimal key section, greatly increase the utilization rate of materials, improve the economy of engineering and save a large amount of investment cost; the method has clear thought, strong applicability and great popularization value.

Drawings

The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the application and together with the description serve to explain the application and not to limit the application. In the drawings:

FIG. 1 is a process flow diagram of one embodiment of the present invention;

FIG. 2 is a structural facade layout of a deck-mounted beam-arch composite rigid frame bridge according to an embodiment of the invention;

FIG. 3 is a key control point profile for one embodiment of the present invention;

FIG. 4 is a graph of a variable quantity profile according to an embodiment of the present invention;

fig. 5 is a structural architecture diagram of the through-girder-arch combined rigid frame bridge according to an embodiment of the invention.

The labels in the figure are: 1. an upper chord beam; 2. a lower chord arch; 3. a midspan conventional beam section; 4. a side span conventional beam section; 5. a main pier; 6. a beam-arch joint section; 7. a pier beam combining section; 8. and (5) a pier arch combining section.

Detailed Description

The method for determining the optimal reasonable bridge forming state of the through-type beam-arch combined rigid frame bridge shown in fig. 1 comprises the following steps:

s1: determining an invariant and a variable of the deck beam-arch combined rigid frame bridge according to the characteristics of a deck beam-arch combined rigid frame bridge structure system, drawing up a reasonable value range of the variable, and setting an initial value, a step length and a final value;

s2: determining a key control point in a reasonable bridge forming state according to the characteristics of a structural system of the upper bearing type beam-arch combined rigid frame bridge, and determining a judgment index in the reasonable bridge forming state and a target limit value of the judgment index according to the key control point;

s3: establishing a finite element analysis model according to the invariants and the variables of the deck beam-arch combined rigid frame bridge; carrying out stress analysis on the structural system of the upper-bearing beam-arch combined rigid frame bridge according to the finite element analysis model, judging whether the calculated judgment index meets the target limit value of the judgment index, and if so, obtaining the optimal value meeting the optimal reasonable variable quantity of the formed bridge state; otherwise, continuously iterating and optimizing the variable quantity through the finite element model to obtain the optimal value which is finally converged into the optimal solution and used as the optimal value of the optimal reasonable bridge-forming state variable quantity;

s4: and carrying out structural design according to the optimal value of the optimal reasonable bridging state variable quantity to obtain the optimal reasonable bridging state of the deck type beam-arch combined rigid frame bridge.

According to the method for determining the optimal reasonable bridge forming state, the bridge forming state of the whole structural system is controlled according to key points, so that the optimal reasonable bridge forming stress state and the optimal reasonable bridge forming line shape of the through-type beam-arch combined rigid frame bridge can be efficiently and accurately found; by establishing a beam-arch combined rigid frame bridge finite element model, accurately simulating the stress state in the construction stage, and applying a normal installation iteration method to carry out calculation and analysis, judging whether the key strength technical parameter and the key rigidity technical parameter of the upper bearing type beam-arch combined rigid frame bridge meet the target limit value or not, the method can accurately determine the most reasonable mid-span ratio of the main beam, the mid-span ratio of the lower chord arch and the arch axis line shape, determine the beam height value with the optimal key section, greatly increase the utilization rate of materials, improve the economy of engineering and save a large amount of investment cost; the method has clear thought, strong applicability and great popularization value.

According to an embodiment of the application, the invariants of the deck-type beam-arch combined rigid frame bridge comprise a main span L and a main pier height H according to the characteristics of a deck-type beam-arch combined rigid frame bridge structural system. The invariance of the deck type beam-arch combined rigid frame bridge is determined according to boundary conditions such as road horizontal and longitudinal line shape, navigation standard, flood traveling requirement and terrain; in the design process, a construction scheme is determined according to the main span L, the main pier height H, the river-related construction condition and the like, and the second-stage constant load and the variable load of the finite element model are determined according to the auxiliary engineering design and the variable load in the operation stage.

According to an embodiment of the application, the variable quantity of the deck-type beam-arch combined rigid frame bridge comprises the following steps: side-to-middle span ratio, lower chord arch rise f and triangular space span L_sArch axis line shape, lower chord arch beam height h₁Height h of upper chord arch standard beam₂Main span middle beam height h₃The height h of the upper chord beam root beam₄。

According to an embodiment of the application, when the stress analysis of the structural system of the top-supported beam-arch combined rigid frame bridge is carried out according to the finite element analysis model, the stress influence degrees of the structural system of the top-supported beam-arch combined rigid frame bridge are subjected to importance grading sequencing according to variable quantities, and iterative computation analysis is carried out according to the influence degree sequence of the variable quantities. By carrying out importance grading sequencing on the variable quantity and analyzing the influence degree of the variable quantity on the structural system along with step adjustment, the structural system and the mechanical behavior of the through-type beam-arch combined rigid frame bridge are more clearly recognized, and the adverse influence on the stress of the structural system caused by the fact that the design parameters are only obtained through engineering experience is avoided.

According to one embodiment of the application, the key control points include pier-beam fastening point a, beam-arch fastening point B, mid-span mid-point C, pier-arch fastening point D, and main pier bottom point E. Firstly, determining key control points of the upper-supporting beam-arch combined rigid frame bridge, secondly, determining key strength parameters and key rigidity parameters according to technical parameters at the key control points, and finally, setting target limit values of evaluation indexes according to mechanical characteristics of a structural system of the upper-supporting beam-arch combined rigid frame bridge; the reasonable bridge forming state of the bridge type can be found quickly, efficiently and accurately.

According to one embodiment of the application, the judgment index of the reasonable bridging state comprises a key strength parameter; the key intensity parameters include: bending moment ratio M of beam arch joint point and pier beam fixing point_B/M_AShear force ratio Qs of beam arch joint point and pier beam fixed joint point_B/Qs_ABending moment ratio M of mid-span point and beam arch joint point_C/M_BAxial force ratio N between side span and mid-span side of pier arch consolidation point_{D side span}/N_{D midspan}Eccentric moment e of pier bottom of main pier_E＝M_E/N_EPositive and negative bending moment ratio M of lower chord arch_a+/M_a-Lower chord arch eccentricity e_a. The key strength parameters are mainly used for judging whether the structure of the upper bearing type beam-arch combined rigid frame bridge meets the requirement of stress in the construction stage so as to ensure the optimal and reasonable stress state of the upper bearing type beam-arch combined rigid frame bridge structure.

According to one embodiment of the application, the judgment index of the reasonable bridging state further comprises a key rigidity parameter; the key stiffness parameters include: road load lower bending span ratio omega₁/L, long-term shrinkage creep lower flex span ratio omega₂And L. The key strength parameters are mainly used for judging whether the structure of the upper-supported beam-arch combined rigid frame bridge meets the rigidity requirement in the bridge forming operation stage so as to ensure the optimal and reasonable bridge forming line shape of the upper-supported beam-arch combined rigid frame bridge structure.

According to an embodiment of the present application, the step S3 includes:

s31: establishing a finite element analysis model according to the invariants and the variables of the deck beam-arch combined rigid frame bridge; carrying out stress analysis calculation on the structural system of the upper bearing type beam-arch combined rigid frame bridge according to the finite element analysis model to obtain a key strength parameter and a key rigidity parameter of the structural system of the upper bearing type beam-arch combined rigid frame bridge;

s32: judging whether the key strength parameter obtained by calculation in the step S31 meets the target limit value of the key strength parameter, if so, obtaining the optimal value meeting the optimal reasonable bridge-forming state variable; otherwise, continuously performing iterative optimization calculation on the variable quantity through the finite element model according to the step length adjustment variable quantity to obtain the optimal value which is finally converged into the optimal solution and is used as the optimal value of the optimal reasonable bridge-forming state variable quantity;

s31: judging whether the key stiffness parameter obtained by calculation in the step S31 meets the target limit of the key stiffness parameter, if so, obtaining the optimal value meeting the optimal reasonable bridge-forming state variable; and otherwise, continuously carrying out iterative optimization calculation on the variable quantity through the finite element model according to the step length adjustment variable quantity to obtain the optimal value which is finally converged into the optimal solution and is used as the optimal value of the optimal reasonable bridge-forming state variable quantity.

According to one embodiment of the application, before the judgment of the reasonable bridge forming state, the finite element calculation result of the strength and the rigidity of each component in the construction stage is ensured to meet the relevant specification requirements.

According to one embodiment of the application, the girder span middle pushing is carried out before the main span middle closing, so that the stress state of the main pier is improved.

According to one embodiment of the application, in order to ensure reasonable bridge alignment, the main beam is set into bridge pre-camber by considering live load and shrinkage creep influence, and construction pre-camber is set in the construction process.

The present invention will be described in further detail with reference to the following test examples and embodiments:

the method is applied to determination of the optimal reasonable bridge forming state of a certain through-type beam-arch combined rigid frame bridge.

As shown in FIG. 2, the deck-type beam-arch combined rigid frame bridge comprises an upper chord beam 1, a lower chord arch 2, a midspan conventional beam section 3, an edge-span conventional beam section 4, a main pier 5, a beam-arch joint section 6, a pier-beam joint section 7 and a pier-arch joint section 8.

According to boundary conditions such as road horizontal and longitudinal line shape, III-level navigation standard, flood traveling requirement and topographic condition, the main girder main span L is determined to be 245m, the pier height H is determined to be 75m, the construction scheme adopts an upper chord girder and lower chord arch double-layer temporary inclined pulling buckling hanging cantilever construction method, the second-stage constant load is determined according to bridge deck pavement and accessory facility design conditions, and the variable load is determined according to road function requirements and other design conditions.

Determining variable quantity and carrying out importance grading sequencing on the stress influence degree of the upper bearing type beam-arch combined rigid frame bridge structure system as follows: is the side-to-middle span ratio, the lower chord arch rise f and the triangular space span L_sArch axis line shape, lower chord arch beam height h₁Height h of upper chord arch standard beam₂Main span middle beam height h₃The height h of the upper chord beam root beam₄As shown in fig. 4.

And according to the stress characteristics of the structural system, setting a value range aiming at the variable quantity, and determining an iteration initial value, a step length and a termination value.

The value range of the variable quantity and the optimal value of the variable quantity in the embodiment are as follows:

according to the stress characteristics of the structural system, aiming at the key control points, five control points are determined, namely a pier-beam fixed point A, a beam-arch joint point B, a mid-span mid-point C, a pier-arch fixed point D and a main pier bottom point E, and are shown in FIG. 3; according to the key control point, determining a key strength parameter as a bending moment ratio (M) of the beam-arch joint point and the pier-beam joint point_B/M_A) Shear ratio (Qs) of beam arch joint point and pier beam joint point_B/Qs_A) Bending moment ratio (M) of mid-span, mid-span and arch joint_C/M_B) Axial ratio of pier arch consolidation point side-span side to mid-span side (N)_{D side span}/N_{D midspan}) Main pier bottom eccentric moment (e)_E＝M_E/N_E) Positive and negative bending moment ratio of lower chord arch (M)_a+/M_a-) Lower chord arch eccentricity (e)_a) (ii) a Determining a key rigidity parameter as a bending-span ratio omega under a lane load₁/L, long-term shrinkage creep lower flex span ratio omega₂/L。

Setting target limit values for the key strength parameters and the key stiffness parameters as follows:

key strength/stiffness parameter	Target limit value of evaluation index
		MB/MA	0.95～1.05
QsB/QsA	0.95～1.05
		Mc/MB	≤0.1
ND side span/ND midspan	0.95～1.05
		eE＝ME/NE	≤BE/15(BE: for the longitudinal dimension of the pier bottom)
Ma+/Ma-	0.95～1.05
		ea	≤BArch/6(BArch: for lower chord arch section height)
ω1/L	≤1/2000
		ω2/L	≤1/4000

Establishing a finite element analysis model of a deck-type beam-arch combined rigid frame bridge with a main span of 245m through Midas-civil software, accurately simulating the pouring construction process of the double-layer temporary inclined pull buckle cantilever, checking a bridge forming state calculation result on the premise of ensuring that the strength and structural rigidity finite element calculation results of all members in the construction stage meet the requirements of relevant specifications, judging whether the calculation result of the key strength parameter meets the target limit value of the strength judgment index, if not, adjusting the variable according to the step length to continue calculating, and if so, continuing to perform index judgment on the key rigidity parameter in the bridge forming operation stage.

Checking the calculation result of the finite element model in the bridge forming operation stage, judging whether the calculation result of the key rigidity parameter meets the target limit of the rigidity judgment index, if not, adjusting the variable according to the step length to continue the calculation, and if so, obtaining the optimal value of the variable meeting the optimal reasonable bridge forming state;

substituting the optimal value of the variable into the finite element model for calculation, and performing main beam mid-span jacking before closing the main span mid-span; and setting the pre-camber of the bridge according to the calculated deformation values of live load and shrinkage creep, and determining the optimal reasonable bridge state of the beam-arch combined rigid frame bridge with the main span of 245 m.

Finally, the above embodiments are only for illustrating the technical solutions of the present invention and not for limiting, although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions may be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all of them should be covered in the claims of the present invention.

Claims (8)

1. A method for determining the optimal reasonable bridge forming state of a deck type beam-arch combined rigid frame bridge is characterized by comprising the following steps:

s1: determining an invariant and a variable of the deck beam-arch combined rigid frame bridge according to the characteristics of a deck beam-arch combined rigid frame bridge structure system, drawing up a reasonable value range of the variable, and setting an initial value, a step length and a final value;

s2: determining a key control point in a reasonable bridge forming state according to the characteristics of a structural system of the upper bearing type beam-arch combined rigid frame bridge, and determining a judgment index in the reasonable bridge forming state and a target limit value of the judgment index according to the key control point;

s3: establishing a finite element analysis model according to the invariants and the variables of the deck beam-arch combined rigid frame bridge; carrying out stress analysis on the structural system of the upper-bearing beam-arch combined rigid frame bridge according to the finite element analysis model, judging whether the calculated judgment index meets the target limit value of the judgment index, and if so, obtaining the optimal value meeting the optimal reasonable variable quantity of the formed bridge state; otherwise, continuously iterating and optimizing the variable quantity through the finite element model to obtain the optimal value which is finally converged into the optimal solution and used as the optimal value of the optimal reasonable bridge-forming state variable quantity;

s4: and carrying out structural design according to the optimal value of the optimal reasonable bridging state variable quantity to obtain the optimal reasonable bridging state of the deck type beam-arch combined rigid frame bridge.

2. The method for determining the optimal reasonable bridge-forming state of the upper-supported girder-arch combined rigid frame bridge according to claim 1, wherein the invariants of the upper-supported girder-arch combined rigid frame bridge comprise a main span L and a main pier height H according to the characteristics of a structural system of the upper-supported girder-arch combined rigid frame bridge.

3. The method for determining the optimal reasonable bridging state of the upper-supported girder-arch combined rigid frame bridge according to claim 1 or 2, wherein the variable quantity of the upper-supported girder-arch combined rigid frame bridge comprises: side-to-middle span ratio, lower chord arch rise f and triangular space span L_sArch axis line shape, lower chord arch beam height h₁Standard beam height h of upper chord beam₂Main span middle beam height h₃The height h of the upper chord beam root beam₄。

4. The method for determining the optimal reasonable bridge-forming state of the upper-supported beam-arch combined rigid frame bridge according to claim 3, wherein when the stress analysis of the structural system of the upper-supported beam-arch combined rigid frame bridge is performed according to the finite element analysis model, the stress influence degrees of the structural system of the upper-supported beam-arch combined rigid frame bridge are subjected to importance grading sequencing according to variable quantities, and iterative computation analysis is performed according to the influence degree sequence of the variable quantities.

5. The method for determining the optimal reasonable bridging state of the deck-type beam-arch combined rigid frame bridge according to claim 1, wherein the key control points comprise a pier-beam fixing point A, a beam-arch joint point B, a mid-span point C, a pier-arch fixing point D and a main pier bottom point E.

6. The method for determining the optimal reasonable bridging state of the through-put beam-arch combined rigid frame bridge according to claim 1, wherein the judgment index of the reasonable bridging state comprises a key strength parameter; the key intensity parameters include: bending moment ratio M of beam arch joint point and pier beam fixing point_B/M_AShear force ratio Qs of beam arch joint point and pier beam fixed joint point_B/Qs_ABending moment ratio M of mid-span point and beam arch joint point_C/M_BAxial force ratio N between side span and mid-span side of pier arch consolidation point_{D side span}/N_{D midspan}Eccentric moment e of pier bottom of main pier_E＝M_E/N_ELower part ofPositive and negative bending moment ratio M of chord arch_a+/M_a-Lower chord arch eccentricity e_a。

7. The method for determining the optimal reasonable bridging state of the through-put beam-arch combined rigid frame bridge according to claim 6, wherein the judgment index of the reasonable bridging state further comprises a key stiffness parameter; the key stiffness parameters include: road load lower bending span ratio omega₁/L, long-term shrinkage creep lower flex span ratio omega₂/L。

8. The method for determining the optimal reasonable bridging status of a deck-type arched-beam composite rigid frame bridge according to claim 7, wherein said step S3 includes

S31: establishing a finite element analysis model according to the invariants and the variables of the deck beam-arch combined rigid frame bridge; carrying out stress analysis calculation on the structural system of the upper bearing type beam-arch combined rigid frame bridge according to the finite element analysis model to obtain a key strength parameter and a key rigidity parameter of the structural system of the upper bearing type beam-arch combined rigid frame bridge;

s32: judging whether the key strength parameter obtained by calculation in the step S31 meets the target limit value of the key strength parameter, if so, obtaining the optimal value meeting the optimal reasonable bridge-forming state variable; otherwise, continuously performing iterative optimization calculation on the variable quantity through the finite element model according to the step length adjustment variable quantity to obtain the optimal value which is finally converged into the optimal solution and is used as the optimal value of the optimal reasonable bridge-forming state variable quantity;

s31: judging whether the key stiffness parameter obtained by calculation in the step S31 meets the target limit of the key stiffness parameter, if so, obtaining the optimal value meeting the optimal reasonable bridge-forming state variable; and otherwise, continuously carrying out iterative optimization calculation on the variable quantity through the finite element model according to the step length adjustment variable quantity to obtain the optimal value which is finally converged into the optimal solution and is used as the optimal value of the optimal reasonable bridge-forming state variable quantity.

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