An assembled trestle structure safety analysis method and system

Abstract

The application discloses a kind of prefabricated trestle structure safety analysis method and system, it is related to civil engineering structure digital twin simulation technical field;Including: obtaining the design data of prefabricated trestle, actual installation measurement data and node connection relationship, establish node level structure twin model and form node contact element set;According to actual installation measurement data, the equivalent initial gap of each node contact element is calculated;Construction load is applied in model, and the closure displacement response is calculated, the node gap closure sequence is generated and the hysteresis bearing node is identified;According to the closure sequence, non-synchronous contact bearing simulation is carried out, and the node counterforce, member internal force and structure displacement are obtained;The simulation results are compared with ideal fitting model, and the stress path distortion position, safety weak node, safety weak component and most unfavorable construction load position are determined.The method can reflect the node non-synchronous bearing process caused by actual installation gap, and improve the accuracy of prefabricated trestle safety analysis result.

Description

Technical Field

[0001] This invention relates to the field of digital twin simulation technology for civil engineering structures, and in particular to a method and system for safety analysis of prefabricated trestle structures. Background Technology

[0002] Prefabricated trestle bridges are widely used in engineering scenarios such as cross-river construction, deep-water foundation construction, temporary construction passages, material transportation passages, and large construction equipment operation platforms. These trestle bridges are typically assembled from steel pipe piles, pile top distribution beams, Bailey bridges, transverse distribution beams, longitudinal distribution beams, bridge decks, and connecting components such as pins, bolts, clamps, and pads. They are characterized by fast erection speed, reusability, easy disassembly and assembly, and adaptability to changes in the construction site. Under the action of construction vehicles, hoisting equipment, or material stacking, the load is usually transferred from the bridge deck to the distribution beams, and then from the Bailey bridges and pile top distribution beams to the steel pipe piles and foundations. Therefore, the fit, support, and connection status of the assembly nodes directly affect the overall stress path and structural safety status of the trestle bridge.

[0003] Existing structural safety analyses of prefabricated trestle bridges typically establish structural calculation models based on design drawings and theoretical component dimensions. These models simplify the nodes between Bailey beams and pile top distribution beams, between transverse distribution beams and Bailey beams, and between bridge decks and distribution beams to ideal fits, ideal hinges, or ideal rigid connections. In this type of analysis, each designed bearing node is usually assumed to participate in load-bearing simultaneously, and the safety of the prefabricated trestle bridge is determined by component stress, node reactions, structural displacement, or overall stability. While this analysis method can reflect the stress situation of the trestle bridge under ideal assembly conditions, it typically lacks specific calculation representations for situations arising during actual installation, such as localized support gaps, differences in pad thickness, component elevation deviations, loose connectors, and poor contact surfaces.

[0004] However, in actual construction, the assembled nodes of a prefabricated trestle bridge often do not enter the load-bearing state simultaneously. Due to the different equivalent initial gaps of different nodes, when construction vehicle loads, hoisting equipment loads, or material loads are applied to the trestle bridge, nodes with smaller gaps or initial fit will bear the load first, while nodes with larger gaps need to undergo further closing displacement of the structure before entering the load-bearing state. This results in differences in the closing sequence of node gaps and delayed load-bearing phenomena. If safety analysis is still performed according to the ideal fit model, it is easy to overlook the force path jumps, local node reaction force concentrations, and component internal force redistribution caused by asynchronous node closure. Consequently, the identification results of weak nodes, weak components, and the most unfavorable construction load locations deviate from the actual assembly state. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing technologies in the safety analysis of prefabricated trestle structures, which typically establish models based on ideal fit conditions, making it difficult to reflect actual installation deviations, initial gaps between nodes, and asynchronous node closure, delayed load bearing, distortion of force paths, and inaccurate identification of local safety risks caused by loose connections. Therefore, this invention proposes a method and system for the safety analysis of prefabricated trestle structures.

[0006] To address the problems existing in the prior art, the present invention adopts the following technical solution: A method for safety analysis of prefabricated trestle structures includes: S1. Obtain the design data, actual installation measurement data and node connection relationships of the prefabricated trestle, establish a node-level structural twin model, and form a set of node contact units; S2. Based on the actual installation measurement data and node connection relationship, calculate the equivalent initial gap of each node contact unit; S3. Apply construction loads to the node-level structural twin model and calculate the closed displacement response of each node contact element; S4. Based on the equivalent initial gap and closing displacement response, generate the node gap closing sequence and identify the hysteresis bearing nodes; S5. Perform asynchronous contact bearing simulation according to the closing sequence of the node gaps to obtain node reaction forces, component internal forces and structural displacements; S6. Compare the nodal reaction forces, component internal forces, and structural displacements with the calculation results of the ideal fitting model to determine the location of the force path distortion. Combine the allowable stress of the components and the allowable bearing capacity of the nodes in the design data to determine the weak nodes and weak components, and output the structural safety analysis results.

[0007] Preferably, the prefabricated trestle bridge includes steel pipe piles, pile top distribution beams, Bailey bridges, transverse distribution beams, longitudinal distribution beams, and bridge deck; the node contact unit includes the support node between the Bailey bridge and the pile top distribution beam, the connection node between the transverse distribution beam and the Bailey bridge, and the pressure-bearing node between the bridge deck and the transverse or longitudinal distribution beam; for each node contact unit, the spatial position of the node, the upper contact member, the lower pressure-bearing member, the load transfer direction, the span to which it belongs, and the relationship with adjacent nodes are recorded.

[0008] Preferably, the equivalent initial gap is determined based on the measured position of the upper contact surface, the measured position of the lower bearing surface, the load transfer direction, and the effective thickness of the pad of the node contact unit; when the measured distance between the upper contact surface and the lower bearing surface in the load transfer direction, after deducting the effective thickness of the pad, is not greater than zero, the node contact unit is determined to be in the initial fitting state; when the measured distance between the upper contact surface and the lower bearing surface in the load transfer direction, after deducting the effective thickness of the pad, is greater than zero, the distance after deduction is determined as the equivalent initial gap of the node contact unit.

[0009] Preferably, the construction load includes construction vehicle load, hoisting equipment load, or material stacking load; the construction load is applied to the corresponding action position in the node-level structural twin model, the relative displacement of each node contact element along the load transfer direction is calculated, and the relative displacement is used as the closed displacement response of the node contact element.

[0010] Preferably, the node gap closing sequence is generated based on the equivalent initial gap and the closing displacement response, including: By comparing the closed displacement response of each nodal contact element with the equivalent initial gap at the same construction load location, the order in which each nodal contact element reaches the closure condition is determined. The node gap closure sequence is generated according to the aforementioned sequence, wherein the node contact units that reach the closure condition first are sorted first, and the node contact units that reach the closure condition later are sorted last.

[0011] Preferably, identifying hysteresis bearer nodes includes: The delayed-load bearing node is determined based on the closing sequence of the node contact units within the same load transfer path. The same load transfer path is a node link formed by the same construction load being transferred to the steel pipe pile through the bridge deck, transverse or longitudinal distribution beam, Bailey beam, and pile top distribution beam. When a node contact element and an adjacent node contact element belong to the same load transfer path, and both participate in bearing load when all node contact elements are in the initial contact state, and the closing sequence of the node contact element is later than that of the adjacent node contact element in the asynchronous contact bearing simulation, the node contact element is determined as a hysteresis bearing node.

[0012] Preferably, asynchronous contact bearing simulation is performed according to the closing sequence of the node gaps to obtain node reactions, component internal forces, and structural displacements, including: Update the load-bearing status of each node contact element according to the node gap closing sequence; For nodal contact elements whose closed displacement response does not reach the equivalent initial gap, no compressive reaction force is assigned; For a node contact element whose closed displacement response reaches the equivalent initial gap, the node reaction force is calculated based on the compression amount and equivalent contact stiffness of the node contact element after closure, and the node reaction force is used to update the internal forces of the component and the structural displacement.

[0013] The equivalent contact stiffness is determined based on the elastic modulus of the material along the pressure path of the node contact unit, the effective pressure-bearing area, and the equivalent compression length. The elastic modulus of the pressure-bearing path material is derived from the prefabricated trestle design data, material performance data, or applicable structural design specifications. The effective bearing area and equivalent compression length are derived from component size data, node connection relationships, or actual installation measurement data.

[0014] Preferably, the location of the stress path distortion is determined, and the weak points and weak members are identified in conjunction with the allowable stress of the components and the allowable bearing capacity of the joints in the design data, including: An ideal fit model is established, in which each designed pressure-bearing node participates in bearing load according to the initial fit state; By comparing the nodal reaction forces, component internal forces, and structural displacements obtained from asynchronous contact bearing simulation with those obtained from the ideal fitting model, the location of force path distortion can be determined. The location of the construction load corresponding to the location of the distorted force path is determined as the candidate most unfavorable construction load location. Based on the degree of force path distortion, nodal reaction force and component internal force, the most unfavorable construction load location is determined from the candidate most unfavorable construction load locations.

[0015] Preferably, the structural safety analysis results include the equivalent initial gap distribution of nodes, the node gap closing sequence, the location of hysteresis bearing nodes, the location of node reaction force concentration, the location of force path distortion, the weak nodes, the weak components, and the most unfavorable construction load location determined based on the location of force path distortion, node reaction force, and component internal force.

[0016] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention establishes a node-level structural twin model by acquiring design data, actual installation measurement data, and node connection relationships of prefabricated trestle bridges. The actual contact relationships between Bailey beams and pile top distribution beams, transverse distribution beams and Bailey beams, and bridge decks and distribution beams are expressed as node contact elements. This allows structural safety analysis to move beyond relying solely on theoretical design positions and ideal fit conditions. By calculating the equivalent initial gap of each node contact element and the closed displacement response under construction loads, actual installation factors such as assembly deviations, support gaps, differences in pad thickness, and loose connections can be transformed into calculable node closure conditions. This allows for the identification of the sequential relationship of different nodes entering the load-bearing state, solving the problem of incorporating the actual node fit state of prefabricated trestle bridges into structural safety analysis.

[0017] 2. This invention further generates the node gap closure sequence based on the equivalent initial gap and closed displacement response, identifies hysteresis-bearing nodes, and then performs asynchronous contact bearing simulation according to the node gap closure sequence to obtain node reactions, component internal forces, and structural displacements. By comparing the asynchronous contact bearing simulation results with the ideal fitting model results, the location of force path distortion, weak nodes, weak components, and the location of the most unfavorable construction load can be determined. This reflects the process of node pre-bearing, hysteresis bearing, reaction force concentration, and component internal force redistribution, improving the matching degree between the safety analysis results of the prefabricated trestle bridge structure and the actual assembly state, and providing a more accurate basis for node verification, pad adjustment, local reinforcement, and construction load arrangement. Attached Figure Description

[0018] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this application, illustrate exemplary embodiments of the invention and, together with their description, serve to explain the invention and do not constitute an undue limitation thereof. In the drawings: Figure 1 This is a flowchart illustrating a safety analysis method for a prefabricated trestle structure according to an embodiment of the present invention. Detailed Implementation

[0019] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0020] This embodiment provides a method for structural safety analysis of prefabricated trestle bridges. The prefabricated trestle bridge in this embodiment is a temporary construction trestle bridge assembled from steel pipe piles, pile top distribution beams, Bailey bridges, transverse distribution beams, longitudinal distribution beams, and bridge decks. The construction load includes at least one of construction vehicle loads, hoisting equipment loads, and material stacking loads. The method described in this embodiment is executed by computer equipment, which can acquire the design data, actual installation measurement data, and node connection relationships of the prefabricated trestle bridge, and complete structural modeling, node state calculation, asynchronous contact bearing simulation, and output of structural safety analysis results. In this embodiment, the node-level structural twin model refers to a computational model established based on the actual installation state of the prefabricated trestle bridge. This model not only expresses the geometric positions and material properties of the steel pipe piles, pile top distribution beams, Bailey beams, transverse distribution beams, longitudinal distribution beams, and bridge deck, but also expresses the node contact relationships and node load-bearing states between the above components. The node-level structural twin model differs from a structural model established only according to the design theoretical positions. It includes at least the component positions corrected by actual installation measurement data, node contact units, construction load application positions, and node load-bearing state update rules. In this embodiment, the design data includes the structural layout diagram of the prefabricated trestle bridge, component size data, material performance data, node connection construction data, component allowable stress, node allowable bearing capacity, and construction load layout data; the actual installation measurement data includes the top elevation of the steel pipe piles after assembly, the top surface position of the pile top distribution beam, the bottom support position of the Bailey beam, the position of the transverse distribution beam, the position of the longitudinal distribution beam, the bridge deck installation position, the thickness of the pad or filling component, and the measured contact surface position at the node; In this embodiment, the actual installation measurement data refers to the data reflecting the actual spatial position of the components and the actual fitting state of the nodes after the prefabricated trestle is installed. This data is used to correct the component positions in the node-level structural twin model and to calculate the equivalent initial gap of the node contact unit. The actual installation measurement data is different from the theoretical dimensional data in the design documents. The design documents are used to provide the theoretical layout and allowable values ​​of the structure, while the actual installation measurement data is used to reflect the actual deviation state after assembly.

[0021] To ensure that the measured positions of different components can be used to calculate the equivalent initial gap of the same node contact unit, the actual installation measurement data are uniformly converted to the same trestle coordinate system. The trestle coordinate system uses the longitudinal extension direction of the prefabricated trestle as the longitudinal coordinate direction, the bridge deck width direction as the transverse coordinate direction, and the vertical direction as the vertical coordinate direction. The measured positions of the top of the steel pipe piles, the pile top distribution beam, the Bailey beam, the transverse distribution beam, the longitudinal distribution beam, and the bridge deck are all represented by this trestle coordinate system. For the contact surface position of the node contact unit, if the contact area is a planar support area, the plane fitted by the contact surface measuring points of the upper contact member in the contact area is taken as the upper contact surface, and the plane fitted by the bearing surface measuring points of the lower bearing member in the contact area is taken as the lower bearing surface. If the contact area is a local line contact or local point contact area, the control measuring point that first contacts along the load transfer direction in the design bearing area is taken as the contact surface position. For node contact units with pads, filler plates, or leveling members, the measured thickness of the pads, filler plates, or leveling members in the load transfer direction is taken as the effective thickness of the pads. Through the above unified coordinates and measuring point rules, the measured position of the upper contact surface, the measured position of the lower bearing surface, the load transfer direction, and the effective thickness of the pads of each node contact unit have the same data reference. The node connection relationships include the bearing relationship between the bridge deck and the transverse or longitudinal distribution beams, the connection relationship between the transverse distribution beams and the Bailey beams, the support relationship between the Bailey beams and the pile top distribution beams, and the bearing relationship between the pile top distribution beams and the steel pipe piles.

[0022] This embodiment provides a safety analysis method for prefabricated trestle structures, which specifically includes the following steps; S1. Obtain the design data, actual installation measurement data and node connection relationships of the prefabricated trestle, establish a node-level structural twin model, and form a set of node contact units; In this step, a basic structural model is established based on the design data of the prefabricated trestle bridge. The basic structural model includes steel pipe piles, pile top distribution beams, Bailey bridge beams, transverse distribution beams, longitudinal distribution beams, and bridge deck. The steel pipe piles are used to bear the vertical loads and horizontal constraints transferred from the superstructure. The pile top distribution beams are set on top of the steel pipe piles to distribute the loads transferred from the Bailey bridge beams to the steel pipe piles. The Bailey bridge beams serve as the main longitudinal load-bearing components. The transverse and longitudinal distribution beams are used to transfer the loads of the bridge deck to the Bailey bridge beams. The bridge deck is used to withstand the wheel pressure of construction vehicles, the reaction force of the outriggers of hoisting equipment, or the material load. After establishing the basic structural model, the geometric state of the basic structural model is corrected according to the actual installation measurement data, so that the position of the steel pipe pile top, the position of the pile top distribution beam, the position of the Bailey beam support, the position of the transverse distribution beam, the position of the longitudinal distribution beam, and the position of the bridge deck in the model are consistent with the actual installation state; the actual installation measurement data is formed by construction measurement records, installation acceptance records, or on-site re-measurement data, which is used to reflect the true structural position after assembly.

[0023] Based on the node connection relationship, node contact elements are defined in the node-level structural twin model. In this embodiment, a node contact element refers to the contact, support, or connection position between two adjacent components in a prefabricated trestle for transmitting compressive loads. A node contact element is not a simple geometric node, but a computational unit with an upper contact component, a lower bearing component, a load transmission direction, an equivalent initial gap, and a bearing state. A node contact element does not transmit compressive reaction force to the lower bearing component in the open state, and transmits compressive reaction force to the lower bearing component according to the equivalent contact stiffness in the closed bearing state. In this embodiment, the node contact element is represented by a unidirectional compression contact element in the node-level structural twin model; the unidirectional compression contact element has an unclosed state and a closed bearing state; when in the unclosed state, the node contact element does not transmit compressive reaction force to the lower bearing member; when in the closed bearing state, the node contact element transmits compressive reaction force to the lower bearing member according to its equivalent contact stiffness; the steel pipe pile, pile top distribution beam, Bailey beam, transverse distribution beam, longitudinal distribution beam and bridge deck are expressed in the node-level structural twin model through beam elements, plate elements or plate-beam combination elements, and the load transfer relationship between each component is established through node contact elements; The node contact unit includes a support node between the Bailey beam and the pile top distribution beam, a connection node between the transverse distribution beam and the Bailey beam, and a bearing node between the bridge deck and the transverse or longitudinal distribution beam. For the support node between the Bailey beam and the pile top distribution beam, the node contact unit is located between the lower chord support area of ​​the Bailey beam and the bearing area on the pile top distribution beam. For the connection node between the transverse distribution beam and the Bailey beam, the node contact unit is located between the lower surface of the transverse distribution beam and the bearing position of the Bailey beam. For the bearing node between the bridge deck and the transverse or longitudinal distribution beam, the node contact unit is located between the lower surface of the bridge deck and the upper surface of the corresponding distribution beam. All of the above node contact units are judged for closure status along their respective load transfer directions. Each node contact element is denoted as Where i is the node number; for each node contact element Record the spatial location of the nodes, the upper contact members, the lower bearing members, the load transfer direction, the span to which they belong, and the relationship between adjacent nodes; Among them, the node spatial location is used to determine the coordinate position of the node contact unit in the prefabricated trestle; the upper contact member refers to the member located above the node and transmitting the load to the lower member during the construction load transfer process; the lower bearing member refers to the member that bears the load of the upper member; the load transfer direction refers to the direction in which the upper contact member in the node contact unit transmits pressure to the lower bearing member; the span to which the node contact unit belongs is used to determine the structural section in which the node contact unit is located; the adjacent node relationship is used to determine the node contact units adjacent to the node contact unit in the same load transfer path; In this embodiment, the load transfer direction is used as the directional reference for unifying the calculation of equivalent initial gap, closed displacement response, and node bearing state. For vertical support nodes, the load transfer direction is the direction in which the upper component presses against the lower component. For nodes with locally inclined contact surfaces, the load transfer direction is determined according to the direction consistent with the compressive force transmission in the normal direction of the designed bearing surface or the actual bearing surface of the node. When calculating the equivalent initial gap and closed displacement response, the load transfer direction corresponding to the same node contact element is used.

[0024] S2. Calculate the equivalent initial gap of each node contact unit based on the actual installation measurement data and node connection relationship; In this embodiment, the equivalent initial gap refers to the distance between the node contact units before effective compressive contact is formed along the load transfer direction before the construction load is applied. The equivalent initial gap is determined by the measured position of the upper contact surface, the measured position of the lower bearing surface, the load transfer direction, and the effective thickness of the pad. It is used to characterize the closing displacement required for the node contact unit to enter the closed bearing state from the unclosed state. An equivalent initial gap of zero indicates that the node contact unit is already in contact in the initial state. An equivalent initial gap greater than zero indicates that the node contact unit needs to generate a corresponding closing displacement in the structure before entering the compressive bearing state. In this step, the node contact element set is... Each gap is identified individually; before calculating the equivalent initial gap, the measurement data of the node contact unit is checked for consistency; the consistency check includes: confirming that the measured position of the upper contact surface and the measured position of the lower bearing surface belong to the same node contact unit; confirming that they have been transformed to the same trestle coordinate system; confirming that the load transfer direction is consistent with the direction of pressure transfer from the upper contact member to the lower bearing member in the node contact unit; confirming that the effective thickness of the pad corresponds to the actual padding position of the node contact unit; if the same node contact unit has multiple measurement sections, the initial gap of each measurement section is calculated separately, and the measurement section that is most unfavorable for early bonding along the load transfer direction is taken as the control section of the node contact unit; For any node contact unit The measured position of the upper contact surface of the node contact unit was determined based on the actual installation measurement data. Measured position of the lower bearing surface Unit vector of load transfer direction and the effective thickness of the pad ; Among them, the measured position of the upper contact surface The actual contact surface position of the upper contact member at the node; the measured position of the lower bearing surface. The actual bearing surface location of the lower bearing member at the node; unit vector of load transfer direction. Determined by the node connection relationship and component layout direction; effective thickness of the pad. The effective thickness of the pad, filler plate, or leveling component already installed at the node in the load transfer direction; Node contact unit equivalent initial gap Determine as follows: ; in, Represents node contact element Equivalent initial gap in the load transfer direction; This indicates the measured distance between the upper contact surface and the lower bearing surface in the load transfer direction; This indicates the effective thickness of the pad or filler component at the node contact unit in the load transfer direction; When the measured distance between the upper contact surface and the lower bearing surface in the load transfer direction, after deducting the effective thickness of the pad, is not greater than zero, the node contact unit is determined as the initial fit state, and its equivalent initial gap is set to zero; when the measured distance between the upper contact surface and the lower bearing surface in the load transfer direction, after deducting the effective thickness of the pad, is greater than zero, the distance after deduction is determined as the equivalent initial gap of the node contact unit. This step yields the equivalent initial gap set for the nodes. The equivalent initial gap set of this node is directly used for subsequent comparison with the closed displacement response, thereby determining whether and when the contact elements of each node are closed.

[0025] S3. Apply construction loads to the node-level structural twin model and calculate the closed displacement response of each node contact element; In this step, construction loads are applied to the node-level structural twin model based on the actual operating conditions of the prefabricated trestle. Construction loads include construction vehicle loads, hoisting equipment loads, or material loads. For construction vehicle loads, the load application location is determined based on the vehicle's wheelbase, wheelbase, and wheel pressure. For hoisting equipment loads, the load application location is determined based on the outrigger location and outrigger reaction force. For material loads, the load application location is determined based on the load area and load intensity. Let x be the location where the construction load applies, and let x be the amplification factor of the construction load relative to the unit load. When a unit load is applied at position x, the nodal contact elements are calculated using a nodal-level structural twin model. Unit closed-loop response along the load transfer direction ; In this embodiment, the closed displacement response refers to the relative proximity displacement of the upper contact member of the node contact unit relative to the lower bearing member along the load transfer direction after the construction load is applied; the closed displacement response is used to compare with the equivalent initial gap to determine whether the node contact unit has reached the closure condition; the closed displacement response is not the overall structural deflection, but the local relative displacement corresponding to the specific node contact unit. When the construction load amplification factor is At that time, node contact unit Closed displacement response Determine as follows: ; in, Represents the nodal contact element under construction load. Closed displacement response along the load transfer direction; This represents the nodal contact element when a unit load is applied at position x. Unit closed-loop response along the direction of load transfer; This indicates the amplification factor of the construction load relative to the unit load; In this embodiment, the closed displacement response is obtained through finite element simulation, structural matrix analysis, or beam structure calculation. Regardless of the structural calculation method used, the load transfer direction of the nodal contact element is kept consistent with the load transfer direction when the equivalent initial gap is determined in step S2, so as to ensure that the closed displacement response and the equivalent initial gap have the same comparison direction. Node contact unit The closure condition is: ; When the node contacts the unit When the closed displacement response reaches its equivalent initial gap, it indicates that the node contact element has entered the closed bearing state from the incomplete contact state; when the closed displacement response does not reach the equivalent initial gap, it indicates that the node contact element has not yet formed an effective pressure-bearing contact. when At that time, node contact unit Load amplification factor at the start of closure Determine as follows: ; when When, it indicates that the node contact element is in the initial contact state, and its closing sequence is among the first under the same load application position; when When the construction load is applied to position x, it means that the contact element of the node will not be closed along the load transfer direction, and the contact element of the node will not participate in the closing sequence order under the load application position. This step yields the closed displacement response and closure condition data of each node contact element under different construction load positions; the closed displacement response and closure condition data are directly used to generate the node gap closure sequence in the subsequent process.

[0026] S4. Based on the equivalent initial gap and the closed displacement response, generate the node gap closing sequence and identify the hysteresis bearing nodes; In this embodiment, the node gap closing sequence refers to the order in which the closing displacement response of each node contact unit reaches its equivalent initial gap under the same construction load position; the node gap closing sequence is used to characterize the time or loading sequence of different node contact units entering the compressive bearing state; the node contact unit that reaches the closing condition first participates in the distribution of compressive reaction force first, and the node contact unit that reaches the closing condition later participates in the distribution of compressive reaction force later. In this step, for the same construction load location x, the closing displacement response of each nodal contact element is compared with its equivalent initial gap to determine the order in which each nodal contact element reaches the closing condition. For nodal contact elements that can close under the construction load location, they are arranged in ascending order of their initial load amplification factor to generate the nodal gap closing sequence. : ; in, Indicates the sequence of node gap closure when the construction load is applied to position x; This refers to the node contact element that first reaches the closure condition and enters the bearing state; This represents the node contact element that finally reaches the closure condition and enters the bearing state; m represents the number of node contact elements that can reach the closure condition at the location x under the construction load. After generating the node gap closing sequence, the delayed bearing nodes are identified according to the closing sequence of the node contact units within the same load transfer path; the same load transfer path is the node link formed by the same construction load being transferred to the steel pipe pile through the bridge deck, transverse or longitudinal distribution beam, Bailey beam, and pile top distribution beam. In this embodiment, a delayed-bearing node refers to a node contact element that, under ideal contact conditions within the same load transfer path, should participate in bearing load together with adjacent node contact elements, but in asynchronous contact bearing simulation considering the equivalent initial gap, its closing sequence is later than that of adjacent node contact elements. The reason for the formation of a delayed-bearing node is that its equivalent initial gap is large, its closing displacement response is small, or both work together, so that it has not yet entered the closed bearing state when adjacent nodes have already generated nodal reaction forces, or it needs to enter the closed bearing state under a larger construction load amplification factor or a later load movement position. Specifically, when a node contact unit and an adjacent node contact unit belong to the same load transfer path, and both participate in bearing load when all node contact units are in the initial contact state, their closed states in asynchronous contact bearing simulation are compared. If an adjacent node contact unit has already met the closing condition and generated node reaction force, while this node contact unit has not yet met the closing condition, or this node contact unit needs to meet the closing condition under a larger construction load amplification factor or a later load movement position, then this node contact unit is determined as a hysteretic bearing node. The determination of the hysteretic bearing node is based on the closing sequence of adjacent node contact units within the same load transfer path, the node reaction force generation state, and the process of change in the position of the construction load. For example, when the wheel pressure of a construction vehicle acts on the bridge deck, the load is transferred through the bridge deck to the transverse distribution beam, and then to the Bailey beam and the pile top distribution beam. Under ideal fit, the connection nodes of the two adjacent Bailey beams below the transverse distribution beam should both participate in bearing the load. However, because one of the nodes has a large equivalent initial gap, its closed displacement response needs to reach a larger value before entering the bearing state, causing the other node to bear the load first and generate a larger nodal reaction force. At this time, the node with the delayed closing sequence is identified as the hysteretic bearing node.

[0027] S5. Perform asynchronous contact bearing simulation according to the closing sequence of node gaps to obtain node reactions, component internal forces and structural displacements; In this embodiment, asynchronous contact load simulation refers to a structural simulation process that updates the load state of node contact units step by step according to the closing sequence of node gaps. In this simulation process, each node contact unit is not set to the load state at the same time, but is judged to enter the closed load state according to its equivalent initial gap and closing displacement response. Node contact units that have not reached the closing condition are not assigned compressive reaction force, while node contact units that have reached the closing condition are assigned compressive reaction force according to the equivalent contact stiffness, and the compressive reaction force is used to update the internal forces of the component and the structural displacement. In this step, asynchronous contact load simulation is performed in the node-level structural twin model according to the closing sequence of the node gaps. The asynchronous contact load simulation does not set all node contact elements to the load state at the same time, but updates the load state of each node contact element step by step according to the order in which the node contact elements reach the closing condition. For any node contact unit Based on its closed displacement response and equivalent initial gap Determine the compression amount after closure : ; in, Represents node contact element The effective compression amount after closure; Represents node contact element The closed displacement response; Represents node contact element The equivalent initial gap; when At that time, node contact unit The closure condition has not yet been met, so no compressive reaction force is distributed; when At that time, node contact unit Once the closure condition is met, the node enters a closed bearing state, and the node reaction force is calculated based on the compression and equivalent contact stiffness of the contact element after closure. : ; in, Represents node contact element Nodal reaction forces; Represents node contact element Equivalent contact stiffness in the load transfer direction; In this embodiment, the equivalent contact stiffness refers to the equivalent stiffness of a node contact element resisting compressive deformation along the load transfer direction under closed bearing conditions. The equivalent contact stiffness is used to characterize the compressive reaction force generated by a unit compression after the node closes. For node contact elements mainly subjected to local bearing pressure of steel components and compression of pads, the equivalent contact stiffness is determined based on the elastic modulus of the bearing path material, the effective bearing area, and the equivalent compression length. For node contact elements with on-site static load verification data, their equivalent contact stiffness is determined based on the on-site static load verification data.

[0028] When using on-site static load verification data to determine the equivalent contact stiffness, the equivalent contact stiffness is determined based on the loading increment and corresponding compressive displacement increment of the node contact element during the static load verification process; where the loading increment is the amount of load change acting on the bearing path of the node contact element during the static load verification process, and the compressive displacement increment is the amount of relative displacement change of the node contact element along the load transfer direction. For a bearing path dominated by elastic compression, the equivalent contact stiffness is... Determine as follows: ; in, Represents node contact element The elastic modulus of the material in the pressure path; Represents node contact element The effective pressure-bearing area; Represents node contact element The equivalent compression length; this relationship is derived from the stiffness relationship of axially elastic compression members in mechanics of materials; the elastic modulus of the material along the pressure path is derived from the design data of the prefabricated trestle, material performance data or applicable structural design specifications; the effective pressure area and equivalent compression length are derived from the component size data, node connection relationship or actual installation measurement data; In the asynchronous contact load simulation, the node contact elements are activated sequentially according to the node gap closure order. Specifically, at each construction load location, the load-bearing state of each node contact element is first determined based on the equivalent initial gap and closure displacement response. For node contact elements that do not meet the closure condition, the compressive stiffness of the node contact element in the load transfer direction is set to zero, so that it does not participate in the distribution of compressive reaction force. For node contact elements that meet the closure condition, the compressive stiffness of the node contact element in the load transfer direction is updated to the equivalent contact stiffness and included in the structural stiffness update process. Subsequently, the node reaction force, component internal force, and structural displacement are recalculated based on the updated load-bearing state of the node contact elements. When the construction load position changes, the closed displacement response of each node contact element is recalculated, and the node bearing state is updated according to the new node gap closing sequence. If the compression of a closed node contact element drops to zero after the load moves, the node contact element exits the compressive bearing state. If a previously unclosed node contact element meets the closing condition after the load moves, the node contact element enters the closed bearing state. Through the above state update rules, the node-level structural twin model can reflect the asynchronous contact process of nodes closing first, closing later, and exiting the bearing state during the construction load movement. Nodal reactions are used to update the component internal forces and structural displacements in the node-level structural twin model. As the location or magnitude of the construction load changes, the node closure state judgment, nodal reaction calculation, component internal force update, and structural displacement update are repeatedly executed to obtain asynchronous contact bearing simulation results under different construction load conditions. The asynchronous contact bearing simulation results include the bearing state, nodal reactions, component internal forces, and structural displacements of each node contact element. This step reflects the following actual process: the initial bonding node first enters the bearing state; the node with a small equivalent initial gap then closes and participates in bearing; the node with a large equivalent initial gap closes with hysteresis after the structure undergoes further deformation; when the hysteresis bearing node closes, the internal forces in the Bailey beam, transverse distribution beam, longitudinal distribution beam and pile top distribution beam are redistributed.

[0029] S6. Compare the nodal reactions, component internal forces, and structural displacements with the calculation results of the ideal fitting model to determine the location of the force path distortion. Combine the allowable stress of the components and the allowable bearing capacity of the nodal in the design data to determine the weak nodes and weak components, and output the structural safety analysis results. In this step, an ideal fit model is established as a comparison model. In this embodiment, the ideal fit model refers to a comparison model in which each designed bearing node is regarded as initially fitted and synchronously participates in bearing under the same component layout, material parameters, construction loads, and boundary conditions as the node-level structural twin model. The ideal fit model is used to provide the results of node reaction force, component internal force, and structural displacement without considering the equivalent initial gap of the nodes. By comparing the ideal fit model with the simulation results of asynchronous contact bearing, the change in the force path caused by the closing sequence of the node gap can be determined. The ideal fitting model and the node-level structural twin model have the same component layout, material parameters, construction loads and boundary conditions. The difference is that in the ideal fitting model, each designed pressure-bearing node participates in bearing according to the initial fitting state, that is, the equivalent initial gap of each node contact unit is treated as zero. Under the same construction load, the nodal reaction force, component internal force and structural displacement obtained from the asynchronous contact bearing simulation and the nodal reaction force, component internal force and structural displacement obtained from the ideal fitting model are obtained respectively; the two are compared to determine the location of the force path distortion. In this embodiment, the force path distortion location refers to the load transfer location where the simulation result of asynchronous contact bearing deviates from the result of the ideal fitting model. For the same construction load application location, if the difference in nodal reaction force of the nodal contact unit is ranked highest within the same load transfer path, or the difference in internal force of the component is ranked highest among similar components in the same span, then the corresponding nodal contact unit location or component location is determined as the force path distortion location. The force path distortion location is also determined based on the force path distortion coefficient. The larger the force path distortion coefficient, the greater the difference between the asynchronous contact bearing state and the ideal fitting state under the construction load application location. The force path distortion location is used to characterize the area where the actual load transfer path deviates from the design synchronous bearing path due to nodal hysteresis bearing and asynchronous nodal closure. For any location x where the construction load is applied, the degree of force path distortion is determined by the force path distortion coefficient. express: ; in, This represents the force path distortion coefficient at the location x where the construction load is applied. This represents the node contact element after considering the node gap closing sequence. Nodal reaction forces; Represents the nodal contact element in the ideal fitting model. The nodal reaction force; m represents the number of nodal contact elements participating in the comparison; the nodal contact elements participating in the comparison are nodal contact elements located in the same load transfer path or the same analysis span under the same construction load application position; when the force path distortion coefficient increases, it indicates that the difference between the load transfer path under asynchronous contact bearing state and the load transfer path under ideal fit state increases.

[0030] After determining the location of the distortion in the force path, the weak nodes and weak components are further identified by combining the allowable stress of the component and the allowable bearing capacity of the node. In this embodiment, a weak node refers to a node contact element in which the node reaction force reaches or exceeds the allowable bearing capacity of the node in the asynchronous contact bearing simulation, or which has the highest safety utilization coefficient in the same load transfer path, or which is located at the location of the distortion in the force path and has a node reaction force higher than the corresponding node reaction force in the ideal fitting model. A weak component refers to a component whose calculated stress reaches or exceeds the allowable stress of the component in the asynchronous contact bearing simulation, or which has the highest safety utilization coefficient in the same type of component in the same span, or which is located in the load transfer path where the hysteresis bearing node or the node reaction force concentration location is located and has a component internal force higher than the corresponding component internal force in the ideal fitting model. For component e, the component safety utilization factor Determine as follows: ; in, Indicates the safety utilization factor of component e; This represents the calculated stress of component e in the asynchronous contact bearing simulation; This indicates the allowable stress of the components in the design data; For node contact units Node security utilization coefficient Determine as follows: ; in, Represents node contact element The safety utilization coefficient; This represents the nodal contact element in the asynchronous contact load simulation. Nodal reaction forces; This indicates the allowable load-bearing capacity of the nodes in the design data.

[0031] In this embodiment, the weak node is determined according to the following rules: when a node contact unit meets any of the following conditions, the node contact unit is determined as a weak node: First, the node safety utilization coefficient reaches or exceeds one; Second, the node safety utilization coefficient is the highest in the same load transfer path; Third, the node contact unit is located at the position of force path distortion, and the node reaction force of the node contact unit in the asynchronous contact bearing simulation is greater than the node reaction force of the corresponding node contact unit in the ideal fitting model. Weak safety components are determined according to the following rules: a component is determined to be a weak safety component when it meets any of the following conditions: First, the component's safety utilization factor reaches or exceeds one; Second, the component's safety utilization factor ranks highest among similar components in the same span; Third, the component is located within the load transfer path of a hysteresis bearing node or a node reaction concentration location, and the component's internal force in the non-synchronous contact bearing simulation is greater than the corresponding component's internal force in the ideal fitting model. In this embodiment, the most unfavorable construction load location refers to the construction load location among the analyzed construction load locations that causes the degree of distortion of the force path, the safety utilization coefficient of the node, or the safety utilization coefficient of the component to reach an unfavorable state. The most unfavorable construction load location is used to characterize the location where the prefabricated trestle bridge has a high structural safety risk due to the node gap closing sequence and the hysteresis bearing effect when construction vehicles, hoisting equipment, or material stacking are applied to that location.

[0032] Specifically, when determining the most unfavorable construction load location, the location of the construction load corresponding to the location of the force path distortion is first identified as the candidate most unfavorable construction load location. Then, the maximum values ​​of the force path distortion coefficient, the node safety utilization coefficient, and the component safety utilization coefficient are calculated for each candidate most unfavorable construction load location. If a candidate most unfavorable construction load location causes at least one of the maximum values ​​of the force path distortion coefficient, the node safety utilization coefficient, and the component safety utilization coefficient to reach the maximum value among all candidate locations, then the candidate most unfavorable construction load location is identified as the most unfavorable construction load location. If multiple candidate most unfavorable construction load locations correspond to different maximum values, then the multiple candidate most unfavorable construction load locations are output together as the set of most unfavorable construction load locations. Output structural safety analysis results; the structural safety analysis results include the equivalent initial gap distribution of nodes, the closing sequence of node gaps, the location of hysteresis bearing nodes, the location of node reaction force concentration, the location of force path distortion, the weak nodes, the weak components, and the location of the most unfavorable construction load.

[0033] In this embodiment, the location of concentrated nodal reaction force refers to the location where the nodal reaction force of the nodal contact element increases relative to the corresponding nodal reaction force in the ideal fitting model during asynchronous contact bearing simulation, or the location where the nodal reaction force ranks first within the same load transfer path; the location of concentrated nodal reaction force is used to indicate the nodal area where the load is temporarily concentrated due to the delayed bearing or lack of closure of adjacent nodes. In this embodiment, the structural safety analysis results are output in at least one of the following formats: tables, node location diagrams, and force path diagrams. Tables list the equivalent initial gap, closing sequence, node reaction force, node safety utilization factor, and hysteresis load-bearing node identifiers for each node contact unit. Node location diagrams indicate hysteresis load-bearing nodes, node reaction force concentration locations, and weak points in the plan or elevation layout of the prefabricated trestle bridge. Force path diagrams show the difference in load transfer paths between the ideal fit model and the asynchronous contact load simulation. Through these output formats, the calculated node gap closing sequence, hysteresis load-bearing nodes, weak points, and most unfavorable construction load locations can be mapped to the actual structural locations of the prefabricated trestle bridge. This embodiment transforms the asynchronous load-bearing process of nodes in a prefabricated trestle caused by installation deviations, support gaps, and loose connections into a calculable node gap closing sequence through the above steps. Based on this node gap closing sequence, asynchronous contact load-bearing simulation is performed. Compared with the traditional structural analysis method that treats all nodes as initially fitted, this embodiment can identify the process of local nodes bearing load first, adjacent nodes bearing load later, and the redistribution of internal forces after the later nodes close. This allows for a more accurate determination of the location of force path distortion and structural safety weaknesses in the prefabricated trestle.

[0034] Taking a prefabricated trestle bridge for construction across a river as an example, the trestle bridge is equipped with multiple spans of Bailey beams along the longitudinal direction. The Bailey beams are supported on the top of steel pipe piles by pile top distribution beams. The bridge deck transfers the wheel pressure of vehicles to the Bailey beams through transverse distribution beams and longitudinal distribution beams. During construction, concrete transport trucks travel along the trestle bridge, and crawler cranes carry out hoisting operations in some spans. The design data, actual installation measurement data, and node connection relationships of the prefabricated trestle bridge were obtained to establish a node-level structural twin model. The support position between the Bailey beam and the pile top distribution beam was defined as the first type of node contact unit, the connection position between the transverse distribution beam and the Bailey beam was defined as the second type of node contact unit, and the bearing position between the bridge deck and the transverse or longitudinal distribution beam was defined as the third type of node contact unit. For each node contact unit, its node spatial position, upper contact member, lower bearing member, load transfer direction, span to which it belongs, and relationship with adjacent nodes were recorded. Based on the on-site measurements of the Bailey beam bottom support surface position, pile top distribution beam top surface position, transverse distribution beam installation position, bridge deck bottom surface position, and pad plate effective thickness, the equivalent initial gap of each node contact unit is calculated; for node contact units that have already been fitted together, the equivalent initial gap is zero; for node contact units with support gaps or loose contact surfaces, the equivalent initial gap is the positive value of the measured spacing minus the effective thickness of the pad plate. In the node-level structural twin model, the concrete transport vehicle wheel pressure and the crawler crane outrigger reaction force are applied respectively, and the closed displacement response of each node contact element along the load transfer direction is calculated. The closed displacement response is compared with the equivalent initial gap to determine the order in which each node contact element reaches the closure condition and to generate the node gap closure sequence. For node contact elements that should share the load with adjacent nodes under ideal fit conditions, but whose closure sequence is later than that of adjacent nodes in asynchronous contact load simulation, they are identified as hysteresis load nodes. Asynchronous contact bearing simulation is performed according to the closing sequence of node gaps; for node contact elements whose closed displacement response does not reach the equivalent initial gap, no compressive reaction force is assigned; for node contact elements whose closed displacement response reaches the equivalent initial gap, the node reaction force is calculated based on the compression after closure and the equivalent contact stiffness, and the node reaction force is used to update the component internal forces and structural displacements in Bailey beams, transverse distribution beams, longitudinal distribution beams, pile top distribution beams, and steel pipe piles.

[0035] In a specific example, three Bailey beam support nodes under the same transverse distribution beam are selected as node contact elements, denoted as the first support node, the second support node, and the third support node, respectively. After on-site installation measurement and deduction of the pad thickness, the equivalent initial clearance of the first support node is zero millimeters, the equivalent initial clearance of the second support node is two millimeters, and the equivalent initial clearance of the third support node is four millimeters. In the ideal fitting model, all three support nodes participate in the load-bearing according to the initial fitting state. The following nodal reactions are the local nodal reactions of the three selected Bailey beam support nodes in the corresponding load transfer path. There are still other support nodes in the prefabricated trestle bridge participating in the overall balance. The load stage before the third support node is closed and the third support node after it is closed correspond to different node contact states during vehicle wheel pressure loading or movement. When the same vehicle wheel pressure acts on the transverse distribution beam, the nodal reactions of the first, second, and third support nodes in the ideal fit model are 90 kN, 100 kN, and 95 kN, respectively, and the reaction force distribution of the three support nodes is relatively close. After the asynchronous contact load simulation of this embodiment, the first support node enters the load state first because the equivalent initial gap is zero. The second support node enters the load state after the transverse distribution beam generates further closing displacement. The third support node enters the load state later because the equivalent initial gap is larger. In the load stage before the third support node closes, the first and second support nodes bear the main reaction force, with the nodal reaction force of the first support node being 145 kN and the nodal reaction force of the second support node being 125 kN. The third support node does not distribute the compressive reaction force. When the third support node closes, the reaction forces of the three support nodes are redistributed, and the nodal reactions of the first, second, and third support nodes are 120 kN, 110 kN, and 60 kN, respectively. The above comparison shows that if the ideal fitting model is used, the three support nodes are judged to be bearing the load together and have similar reaction forces. However, after using the asynchronous contact load simulation of this embodiment, the hysteretic load state of the third support node and the reaction force concentration phenomenon of the first and second support nodes before the third support node closes can be identified. Therefore, the locations of the first and second support nodes are determined as the locations of node reaction force concentration, the third support node is determined as the hysteretic load node, and the corresponding transverse distribution beam and Bailey beam support areas are included in the scope of safety weak component review.

[0036] Finally, the simulation results of asynchronous contact bearing are compared with the calculation results of the ideal fitting model to determine the location of the force path distortion. If a Bailey beam support node shares the load with the adjacent support node in the ideal fitting model, but in the asynchronous contact bearing simulation, the node bears a larger reaction force first due to the delayed closure of the adjacent node, then the location of the support node is determined as the node reaction force concentration location. If the node reaction force concentration location also causes the internal force of the corresponding Bailey beam lower chord or pile top distribution beam to increase, then the support node is determined as a safety weak node, and the corresponding Bailey beam or pile top distribution beam is determined as a safety weak component.

[0037] This invention also provides a safety analysis system for prefabricated trestle structures. In this embodiment, the functions of each module / unit of the system are as follows: The twin modeling module is used to acquire design data, actual installation measurement data and node connection relationships of the prefabricated trestle, establish a node-level structural twin model, and form a set of node contact units; The gap calculation module is used to calculate the equivalent initial gap of each node contact unit based on the actual installation measurement data and node connection relationship. The closed response module is used to apply construction loads to the node-level structural twin model and calculate the closed displacement response of each node contact element. The closure sequencing module is used to generate the node gap closure sequence based on the equivalent initial gap and the closure displacement response, and to identify the hysteresis bearing nodes; The asynchronous simulation module is used to perform asynchronous contact bearing simulation according to the closing sequence of the node gaps to obtain node reactions, component internal forces and structural displacements. The safety analysis module is used to compare the nodal reaction forces, component internal forces, and structural displacements with the calculation results of the ideal fitting model, determine the location of the force path distortion, and, in conjunction with the component allowable stress and nodal allowable bearing capacity in the design data, determine the weak nodes and weak components, and output the structural safety analysis results.

[0038] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A safety analysis method for prefabricated trestle structures, characterized in that, Includes the following steps: S1. Obtain the design data, actual installation measurement data and node connection relationships of the prefabricated trestle, establish a node-level structural twin model, and form a set of node contact units; S2. Based on the actual installation measurement data and node connection relationship, calculate the equivalent initial gap of each node contact unit; S3. Apply construction loads to the node-level structural twin model and calculate the closed displacement response of each node contact element; S4. Based on the equivalent initial gap and closing displacement response, generate the node gap closing sequence and identify the hysteresis bearing nodes; S5. Perform asynchronous contact bearing simulation according to the closing sequence of the node gaps to obtain node reaction forces, component internal forces and structural displacements; S6. Compare the nodal reaction forces, component internal forces, and structural displacements with the calculation results of the ideal fitting model to determine the location of the force path distortion. Combine the allowable stress of the components and the allowable bearing capacity of the nodes in the design data to determine the weak nodes and weak components, and output the structural safety analysis results.

2. The method for safety analysis of prefabricated trestle structures according to claim 1, characterized in that, The prefabricated trestle bridge includes steel pipe piles, pile top distribution beams, Bailey bridges, transverse distribution beams, longitudinal distribution beams, and bridge decks; the node contact units include support nodes between Bailey bridges and pile top distribution beams, connection nodes between transverse distribution beams and Bailey bridges, and bearing nodes between bridge decks and transverse or longitudinal distribution beams; for each node contact unit, the spatial location of the node, the upper contact member, the lower bearing member, the load transfer direction, the span to which it belongs, and the relationship with adjacent nodes are recorded.

3. The method for safety analysis of prefabricated trestle structures according to claim 1, characterized in that, The equivalent initial gap is determined based on the measured position of the upper contact surface, the measured position of the lower bearing surface, the load transfer direction, and the effective thickness of the pad of the node contact unit. When the measured distance between the upper contact surface and the lower bearing surface in the load transfer direction, after deducting the effective thickness of the pad, is not greater than zero, the node contact unit is determined to be in the initial fitting state. When the measured distance between the upper contact surface and the lower bearing surface in the load transfer direction, after deducting the effective thickness of the pad, is greater than zero, the distance after deduction is determined as the equivalent initial gap of the node contact unit.

4. The method for safety analysis of prefabricated trestle structures according to claim 1, characterized in that, The construction load includes construction vehicle load, hoisting equipment load, or material stacking load; the construction load is applied to the corresponding action position in the node-level structural twin model, the relative displacement of each node contact element along the load transfer direction is calculated, and the relative displacement is used as the closed displacement response of the node contact element.

5. The method for safety analysis of prefabricated trestle structures according to claim 1, characterized in that, Based on the equivalent initial gap and the closing displacement response, the nodal gap closing sequence is generated, including: By comparing the closed displacement response of each nodal contact element with the equivalent initial gap at the same construction load location, the order in which each nodal contact element reaches the closure condition is determined. The node gap closure sequence is generated according to the aforementioned sequence, wherein the node contact units that reach the closure condition first are sorted first, and the node contact units that reach the closure condition later are sorted last.

6. The method for safety analysis of prefabricated trestle structures according to claim 5, characterized in that, Identifying hysteresis bearer nodes includes: The delayed-load bearing node is determined based on the closing sequence of the node contact units within the same load transfer path. The same load transfer path is a node link formed by the same construction load being transferred to the steel pipe pile through the bridge deck, transverse or longitudinal distribution beam, Bailey beam, and pile top distribution beam. When a node contact element and an adjacent node contact element belong to the same load transfer path, and both participate in bearing load when all node contact elements are in the initial contact state, and the closing sequence of the node contact element is later than that of the adjacent node contact element in the asynchronous contact bearing simulation, the node contact element is determined as a hysteresis bearing node.

7. The method for safety analysis of prefabricated trestle structures according to claim 1, characterized in that, Asynchronous contact bearing simulation was performed according to the aforementioned node gap closing sequence to obtain node reactions, component internal forces, and structural displacements, including: Update the load-bearing status of each node contact element according to the node gap closing sequence; For nodal contact elements whose closed displacement response does not reach the equivalent initial gap, no compressive reaction force is assigned; For a node contact element whose closed displacement response reaches the equivalent initial gap, the node reaction force is calculated based on the compression amount and equivalent contact stiffness of the node contact element after closure, and the node reaction force is used to update the internal forces of the component and the structural displacement. The equivalent contact stiffness is determined based on the elastic modulus of the material along the pressure path of the node contact unit, the effective pressure-bearing area, and the equivalent compression length. The elastic modulus of the pressure-bearing path material is derived from the prefabricated trestle design data, material performance data, or applicable structural design specifications. The effective bearing area and equivalent compression length are derived from component size data, node connection relationships, or actual installation measurement data.

8. The method for safety analysis of prefabricated trestle structures according to claim 1, characterized in that, Determine the location of stress path distortion, and based on the allowable stress of components and the allowable bearing capacity of nodes in the design data, identify the weak points and weak components, including: An ideal fit model is established, in which each designed pressure-bearing node participates in bearing load according to the initial fit state; By comparing the nodal reaction forces, component internal forces, and structural displacements obtained from asynchronous contact bearing simulation with those obtained from the ideal fitting model, the location of force path distortion can be determined. The location of the construction load corresponding to the location of the distorted force path is determined as the candidate most unfavorable construction load location. Based on the degree of force path distortion, nodal reaction force and component internal force, the most unfavorable construction load location is determined from the candidate most unfavorable construction load locations.

9. The method for safety analysis of prefabricated trestle structures according to claim 8, characterized in that, The structural safety analysis results include the equivalent initial gap distribution of nodes, the closing sequence of node gaps, the location of hysteresis bearing nodes, the location of node reaction force concentration, the location of force path distortion, the weak nodes, the weak components, and the location of the most unfavorable construction load determined based on the location of force path distortion, node reaction force, and component internal force.

10. A prefabricated trestle structure safety analysis system, used to execute the prefabricated trestle structure safety analysis method according to any one of claims 1-9, characterized in that, include: The twin modeling module is used to acquire design data, actual installation measurement data and node connection relationships of the prefabricated trestle, establish a node-level structural twin model, and form a set of node contact units; The gap calculation module is used to calculate the equivalent initial gap of each node contact unit based on the actual installation measurement data and node connection relationship. The closed response module is used to apply construction loads to the node-level structural twin model and calculate the closed displacement response of each node contact element. The closure sequencing module is used to generate the node gap closure sequence based on the equivalent initial gap and the closure displacement response, and to identify the hysteresis bearing nodes; The asynchronous simulation module is used to perform asynchronous contact bearing simulation according to the closing sequence of the node gaps to obtain node reactions, component internal forces and structural displacements. The safety analysis module is used to compare the nodal reaction forces, component internal forces, and structural displacements with the calculation results of the ideal fitting model, determine the location of the force path distortion, and, in conjunction with the component allowable stress and nodal allowable bearing capacity in the design data, determine the weak nodes and weak components, and output the structural safety analysis results.

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