CN-121834997-B - Interactive design method for concrete side span and cast-in-situ bracket of hybrid beam cable-stayed bridge

CN121834997BCN 121834997 BCN121834997 BCN 121834997BCN-121834997-B

Abstract

The application relates to the technical field of bridges, and provides a method for interactively designing a concrete side span of a hybrid beam cable-stayed bridge and a cast-in-situ bracket, which realizes the unification of structural safety, structural economy and bracket cost saving property and saves the cost of the whole construction process through the interactive design of the concrete side span and the cast-in-situ bracket; in the interactive design process, a bracket batch dismantling scheme, prestress beam arrangement and three-level adjustment priority of the girder geometry are established, the influence of concrete side span parameter adjustment on a middle span steel girder is reduced to the minimum, the bracket meeting the stress requirement and the bracket crossing flood demand is comprehensively considered, the structure newly-added cost and the bracket spreading cost are comprehensively considered, the most economical combination scheme is selected, the minimization of the engineering whole life cycle cost on the premise of ensuring the safety is realized, and the risk of blocking water and choking water of a large number of brackets in the flood period is thoroughly avoided on the premise of ensuring the structural stress safety, and the smoothness of flood and the safety of the bracket structure are ensured.

Inventors

XU ZIRAN
ZHOU XUAN
SUN XIUGUI
PENG JIANGHUI
Wang Huidui
LIU YONG
LI YU
LI WENWU
WANG TIAN
WU YING
CUI JIANFENG
CHENG LIJUAN

Assignees

湖南省交通规划勘察设计院有限公司
长沙市规划设计院有限责任公司

Dates

Publication Date: 20260512
Application Date: 20260316

Claims (9)

1. The interactive design method for the concrete side span of the hybrid beam cable-stayed bridge and the cast-in-situ bracket is characterized by comprising the following steps of: S1, acquiring initial structural parameters of a concrete side span main beam, the maximum allowable water blocking area of a conventional bracket and the actual water blocking area of the conventional bracket; s2, if the actual water blocking area is larger than the maximum allowable water blocking area, a plurality of bracket batch dismantling schemes are planned; s3, establishing a full-bridge structure analysis model, dividing construction stages according to an actual construction sequence, inputting the initial structural parameters and a plurality of bracket batch dismantling schemes, and calculating the stress state of a concrete side span girder and the stress state of a bracket in each construction stage; s4, judging whether the stress state of the concrete side span main beam and the stress state of the bracket in each construction stage meet preset safety standards, if so, marking the current bracket batch dismantling scheme as a feasible scheme, entering a step S7, otherwise, entering a step S5; S5, keeping the size of the main beam unchanged, adjusting the arrangement parameters of the prestress beam, generating a plurality of prestress adjustment sub-schemes, and returning to the step S3 for rechecking, if the prestress adjustment sub-scheme exists to enable all construction stages to meet the safety standard, marking the combination of the current bracket batch dismantling scheme and the prestress adjustment sub-scheme as a feasible scheme, entering the step S7, otherwise entering the step S6; S6, gradually adjusting the geometric dimension of the concrete side span main beam according to a preset priority, returning to the step S5 for prestress optimization and checking calculation every time until the combination of the geometric dimension and the prestress parameter meeting the safety standard is found, marking the combination as a feasible scheme, and entering the step S7; And S7, summarizing all the feasible schemes, calculating the comprehensive cost of each feasible scheme, and selecting the feasible scheme with the minimum comprehensive cost as the optimal construction scheme to output.
2. The method for interactively designing the concrete side span and the cast-in-situ bracket of the hybrid cable-stayed bridge according to claim 1, wherein the step S1 of obtaining the initial structural parameters of the main beam of the concrete side span comprises the following steps: Establishing a full-bridge finite element model according to the material characteristics and the geometric characteristics of a bridge structure, and calculating according to a one-time bridge construction mode based on a minimum bending energy principle to obtain the primary structure size and the primary arrangement of prestressed bundles of the concrete side span main girder; Dividing construction stages according to a conventional construction procedure, simulating a full-framing frame of side-span concrete in the full-bridge finite element model, and setting the full-framing frame as a compression spring unit only; Running the full-bridge finite element model to perform overall process construction simulation calculation, and accumulating the structural stress states of each construction stage to obtain the stress distribution of the concrete side span main beam in overall process construction; Comparing the stress distribution with a preset stress safety standard, optimally adjusting the primary structure size and the primary arrangement of the prestressed bundles according to the stress distribution at the part which does not meet the stress safety standard, and outputting the optimized initial structure parameters of the concrete side span main girder, wherein the initial structure parameters comprise girder height, web thickness, top plate thickness, bottom plate thickness and the arrangement parameters of the prestressed bundles.
3. The method for interactively designing the concrete side span of the hybrid beam cable-stayed bridge and the cast-in-situ bracket according to claim 1, wherein the step S1 of obtaining the maximum allowable water blocking area of the conventional bracket comprises the following steps: obtaining a flood-discharge water-blocking rate allowable value specified at a bridge position, a water-blocking area of a permanent bridge pier and a river channel water cross-section area corresponding to a flood designed at the bridge position; calculating the maximum allowable water blocking total area according to the allowable value of the row Hong Zushui rate and the area of the river channel water cross section; and calculating the difference between the maximum allowable water blocking total area and the water blocking area of the permanent bridge pier to obtain the maximum allowable water blocking area of the conventional bracket.
4. The method for interactive design of concrete side spans and cast-in-situ brackets of the hybrid beam cable-stayed bridge according to claim 1, wherein the step S2 comprises the following steps: S21, if the actual water blocking area is larger than the maximum allowable water blocking area, a plurality of bracket batch dismantling schemes are planned, wherein each bracket batch dismantling scheme is generated according to the following principle that at least two steel pipe columns form a bracket group as a minimum unit for bracket dismantling; S22, for each bracket batch dismantling scheme, calculating the maximum instantaneous water blocking area in each dismantling stage, and verifying whether the maximum instantaneous water blocking area is smaller than or equal to the maximum allowable water blocking area; S23, screening out all the bracket batch dismantling schemes meeting the condition that the maximum instantaneous water blocking area is smaller than or equal to the maximum allowable water blocking area, and obtaining various bracket batch dismantling schemes.
5. The method for interactive design of concrete side spans and cast-in-situ brackets of the hybrid-beam cable-stayed bridge according to claim 4, wherein the step S3 comprises the following steps: s31, a full-bridge structure analysis model is established, construction stages are divided according to an actual construction sequence, and the initial structural parameters and various bracket batch dismantling schemes are input into the full-bridge structure analysis model; s32, in each construction stage, simulating the cast-in-situ bracket into only pressed spring units, sequentially passivating the spring units at corresponding positions in the corresponding dismantling stages according to the dismantling time sequence in each bracket batch dismantling scheme, and simultaneously applying node forces with the same magnitude and opposite directions as the supporting counter force of the spring units at the same node position before passivation so as to simulate the load transfer in the bracket dismantling process; and S33, operating the full-bridge structure analysis model, and calculating and outputting the concrete section edge normal compression stress and the concrete section edge concrete normal tension stress of the concrete side span main beam at each construction stage, and the axial force value and the bending moment value of each steel pipe column as the stress state of the concrete side span main beam and the stress state of the bracket.
6. The method for interactive design of concrete side span and cast-in-situ bracket of cable-stayed bridge with hybrid beam according to claim 5, wherein the step S4 of judging whether the stress state of the concrete side span main beam and the stress state of the bracket in each construction stage meet the preset safety standard comprises the following steps: Judging whether the following conditions are simultaneously met in each construction stage: the concrete side span main beam meets the following conditions: and the following steps: Wherein, the method comprises the steps of, In order to ensure that the concrete cross section edge normal compressive stress of the concrete side span girder in the construction stage, In order to ensure that the concrete side span main beam has concrete section edge concrete normal tensile stress in the construction stage, Is designed to be the compressive strength of the concrete axle center, The design value of the tensile strength of the concrete axle center is designed; The second condition is that the strength of the steel pipe bracket meets the following conditions: Wherein, the method comprises the steps of, Is an importance coefficient of the steel pipe support structure, Is the axial force value of the steel pipe bracket under the load, To take into account the effective cross-sectional area of the steel tube stent for local stability effects, Designing allowable strength for steel specified by specifications; Thirdly, the stability of the steel pipe bracket meets the following conditions: Wherein, the method comprises the steps of, Is a bending moment of the steel pipe bracket around the y axis under the load action, Is a bending moment of the steel pipe bracket around the z-axis under the load action, Is the overall stability reduction coefficient of the axial compression member, 、 The section moduli of the effective section relative to the y-axis and the z-axis, respectively, taking into account the local stability effects; If all the construction stages simultaneously meet the first, second and third conditions, judging that the current bracket batch dismantling scheme meets the preset safety standard, otherwise, judging that the current bracket batch dismantling scheme does not meet the preset safety standard.
7. The method for interactive design of concrete side spans and cast-in-situ brackets of the hybrid cable-stayed bridge according to claim 6, wherein in the step S5, the main beam size is kept unchanged, the arrangement parameters of the prestressed bundles are adjusted, and the generation of various prestressed adjustment sub-schemes comprises the following steps: s51, acquiring the geometric dimension of the main beam corresponding to the current bracket batch dismantling scheme which is judged by the step S4 not to meet the preset safety standard, wherein the geometric dimension of the main beam comprises beam height, web thickness, top plate thickness and bottom plate thickness; S52, keeping the geometric dimension of the main beam unchanged, and adjusting the arrangement parameters of the prestressed bundles according to the following priority order, namely firstly adjusting the tensioning order of the prestressed bundles, secondly adjusting the line shape of the prestressed bundles, and finally adjusting the steel bundle type of the prestressed bundles; s53, generating a prestress adjustment sub-scheme after each time of adjusting the arrangement parameters, wherein the prestress adjustment sub-scheme comprises an adjusted tensioning sequence, a line shape and a steel beam model; And S54, respectively combining the generated various prestress adjustment sub-schemes with the current bracket batch dismantling scheme to serve as the various prestress adjustment sub-schemes.
8. The method for interactive design of concrete side spans and cast-in-situ brackets of the hybrid-beam cable-stayed bridge according to claim 6, wherein the step S6 comprises the following steps: s61, acquiring the girder geometric dimension corresponding to the current bracket batch dismantling scheme which still does not meet the preset safety standard after the pre-stress beam is adjusted in the step S5; S62, gradually adjusting the geometric dimension of the main beam according to the following priority order, namely firstly adjusting the thickness of a web plate, adjusting the level difference to be 5 cm-10 cm, secondly adjusting the thickness of a top plate or the thickness of a bottom plate, adjusting the level difference to be 5 cm-10 cm, and finally adjusting the height of a beam, and adjusting the level difference to be 5 cm-10 cm; S63, generating a new main beam structure scheme after each size adjustment is completed, and returning to the step S5 to perform prestress beam parameter optimization and checking calculation again; S64, repeating steps S62 to S63 until a set of combinations of geometry and pre-stressing beam parameters is found that meet the safety criteria, marking the combination as a viable solution and proceeding to step S7.
9. The method for interactive design of concrete side spans and cast-in-situ brackets of the hybrid beam cable-stayed bridge according to claim 1, wherein the step S7 comprises the following steps: S71, summarizing all feasible schemes, wherein each feasible scheme comprises the final geometric dimension of a concrete side span main beam, the final arrangement parameters of a prestressed beam and the final batch dismantling scheme of a cast-in-situ bracket; S72, acquiring the standard girder material cost and the standard bracket service period corresponding to the conventional construction scheme; S73, for each feasible scheme, calculating the increment of the main beam material cost relative to the reference main beam material cost; S74, for each feasible scheme, calculating the actual service cycle of each bracket grouping according to the dismantling time sequence in the final batch dismantling scheme, and calculating the bracket material amortization cost; S75, for each feasible scheme, calculating the comprehensive cost according to the increment and the stand material amortization cost; S76, comparing the comprehensive cost of all the feasible schemes, and selecting the feasible scheme with the minimum comprehensive cost as the optimal construction scheme to output.

Description

Interactive design method for concrete side span and cast-in-situ bracket of hybrid beam cable-stayed bridge Technical Field The invention relates to the technical field of bridges, in particular to a method for interactively designing concrete side spans and cast-in-situ brackets of a hybrid beam cable-stayed bridge. Background The cable-stayed bridge with the mixed beam has been widely used because of the characteristics of strong crossing capability and high rigidity. The side span of the hybrid beam cable-stayed bridge is a concrete structure with large self-weight and large rigidity, and the side span concrete plays roles of anchoring and weighting. Because of the great difference of dead weights of the side span and the middle span, the construction of the symmetrical cantilever cannot be performed conventionally. In the prior art, pouring and pre-stressing tensioning construction of the concrete side span are usually completed on a bracket, symmetrical tensioning of the side span and the stay cable of the middle span is correspondingly completed along with sequential installation of main girder sections of the main span, and the side span cast-in-situ bracket is removed once again after closure of the main span and tensioning of the full-bridge stay cable are completed. However, the side span bracket of the large-span hybrid beam cable-stayed bridge has large water blocking rate and long construction period, and can not finish girder construction and bracket dismantling in a dead water period, and the conventional construction process has the following problems and disadvantages: (1) According to the river-related bridge water conservancy technology regulations in various places, the allowable water blocking area of the river-crossing bridge is generally 3.5% -7%. The water blocking rate in the river channel can greatly exceed the allowable water blocking rate due to a large number of cast-in-situ brackets, normal flood is seriously hindered during flood, water is choked, and serious danger can be caused to structures on two sides of the river channel. (2) The sudden flood period is usually accompanied by a large amount of floaters, the water blocking effect is greatly increased by densely distributed temporary supports, and the temporary supports are in danger of being washed out by flood in severe cases, so that the finished bridge structure is further damaged. The prior art lacks accurate simulation means for the stress state of the structure in the bracket dismantling process, and related personnel cannot prejudge whether the main beam cracks or not and whether the rest of the bracket is unstable or not in the way of the bracket batch dismantling, so that only a conservative one-time dismantling strategy can be adopted. (3) The natural foundation strength is greatly influenced by flood, cast-in-situ supports needing to pass flood periods are usually cast-in-situ piles or driven into steel pipe piles, the construction period of support pile foundations is long, the driven steel pipe piles cannot be effectively recycled, and the support foundation cost is high. In view of the above, it is necessary to provide a method for the interactive design of concrete side spans and cast-in-situ brackets of a hybrid cable-stayed bridge to solve or at least alleviate the above-mentioned drawbacks. Disclosure of Invention The invention mainly aims to provide a method for interactively designing concrete side spans and cast-in-situ brackets of a hybrid beam cable-stayed bridge, which aims to solve the technical problems that in the prior art, the concrete side spans of the hybrid beam cable-stayed bridge are stiff in the dismantling time (the bridge must be dismantled once after closure, flood warning cannot be dynamically adapted) and the girder structure is designed according to the bridge formation state, and the stress requirement of batch dismantling of the brackets in the construction process is not considered. In order to achieve the purpose, the invention provides a method for interactively designing a concrete side span of a hybrid beam cable-stayed bridge and a cast-in-situ bracket, which comprises the following steps: S1, acquiring initial structural parameters of a concrete side span main beam, the maximum allowable water blocking area of a conventional bracket and the actual water blocking area of the conventional bracket; s2, if the actual water blocking area is larger than the maximum allowable water blocking area, a plurality of bracket batch dismantling schemes are planned; s3, establishing a full-bridge structure analysis model, dividing construction stages according to an actual construction sequence, inputting the initial structural parameters and a plurality of bracket batch dismantling schemes, and calculating the stress state of a concrete side span girder and the stress state of a bracket in each construction stage; s4, judging whether the stress state of the concrete side span main beam a