Large-span steel structure rapid butt joint installation process for constructional engineering

Abstract

The invention discloses a large-span steel structure rapid butt joint installation technology for constructional engineering. The process comprises the following steps: placing a to-be-butted steel structure section on a flexible jig frame to obtain a closure gap; defining an active thermal compensation area in a non-welding area of the main stress component at a preset axial distance from the to-be-butt-jointed welding seam; the area is heated in a controlled mode, and the butt joint end faces are pushed to move relatively through axial thermal expansion displacement generated by the area till the closing gap is closed; carrying out backing welding on the butt joint end face in a constant temperature state of controlled compensation in the area; and in the welding seam filling and capping stage, according to the welding heat input parameters and the shrinkage prediction model, the cooling rate of the active thermal compensation area is dynamically adjusted, and the synchronous cold shrinkage amount of the area is used for offsetting or reducing the shrinkage deformation amount of the welding seam area. According to the method, a large mechanical stretching tool is eliminated, micro-stress fitting of the butt joint end faces is achieved, the overall residual stress level is remarkably reduced, and the anti-fatigue performance of the structure is improved.

Description

Technical Field

[0001] This invention relates to the field of building engineering and bridge construction technology, specifically to a rapid connection and installation process for large-span steel structures. Background Technology

[0002] In the aerial joining and closure process of long-span steel structures such as long-span roofs, trusses, and steel box girder bridges, gaps usually exist between the end faces to be joined due to factors such as manufacturing errors, ambient temperature fluctuations, and structural self-weight deflection.

[0003] In existing technologies, temperature changes and heat input are generally considered negative factors leading to structural deformation and residual stress. Therefore, conventional processes typically avoid introducing heat into non-weld areas, and often use mechanical means such as large hydraulic jacks, chain hoists, or clamps to forcefully cold stretch or cold support to eliminate the closing gap.

[0004] However, the tensile force generated by mechanical means can trap the initial assembly stress within the structure. Furthermore, during the welding of the closure joint, the cooling of the locally heated molten pool causes volume shrinkage, generating residual welding stress. The superposition of these two stresses may lead to deflection and subsidence of the structure after the supports are unloaded, or fatigue cracking during long-term service. Additionally, large mechanical tooling presents operational inconvenience and safety hazards when working at heights. Summary of the Invention

[0005] The technical problem to be solved by this invention is: how to reduce the mechanical assembly stress during the closure process of large-span steel structures and suppress the shrinkage stress generated during the welding stage, thereby improving the docking accuracy and reducing the residual stress level.

[0006] The above-mentioned technical objective of this invention is achieved through the following technical solution: a rapid connection and installation process for large-span steel structures used in building engineering, comprising the following steps: S1. Place the steel structure section to be connected on the flexible jig, keep it in a natural position, and obtain the measurement value of the closing gap between the docking end faces; S2. Define the active thermal compensation zone in the non-welding zone of the main load-bearing component at a predetermined axial distance from the weld to be butted; S3. The active thermal compensation zone is heated in a controlled manner to generate axial thermal expansion displacement, thereby pushing the mating end faces to move relative to each other until the closing gap is closed; S4. While maintaining controlled compensation in the active thermal compensation zone, perform root pass welding on the mating end face; S5. During the weld filling and cover welding stages, the cooling rate of the active heat compensation zone is dynamically adjusted so that the synchronous cooling shrinkage of the active heat compensation zone in the time dimension is used to offset or reduce the welding shrinkage of the butt joint surface, thereby effectively suppressing the overall residual stress of the structure.

[0007] Furthermore, in step S2, the range of the predetermined axial distance is defined as: 1.5m to 5.0m along the axial distance of the component from the weld to be butted; and the maximum temperature for heating the active thermal compensation zone is limited to being lower than the metallographic phase transformation temperature of the large-span steel structure base material.

[0008] Furthermore, in step S3, the control unit determines the target temperature rise based on the measured value of the closing gap, the linear expansion coefficient of the main force-bearing component, and the length of the active thermal compensation zone; The control unit uses the target temperature rise as a reference and dynamically adjusts the heating power in conjunction with the real-time displacement feedback signal until the gap is completely closed and then locks the heating state.

[0009] Furthermore, in steps S1 and S3, an external bridging displacement sensor is used to obtain the measured value of the closing gap and the real-time displacement feedback signal. The external bridging displacement sensor is installed as follows: its main body box is installed on the outer surface of the steel structure on one side of the docking end face, its fixed anchor point or reflective target is installed on the outer surface of the steel structure on the other side of the docking end face, and its measurement connection line or optical path crosses the outside of the closing gap to avoid physical interference of the sensor when the closing gap is closed.

[0010] Furthermore, in step S5, the control unit dynamically adjusts the cooling rate of the active heat compensation zone based on the welding heat input parameters and the preset weld shrinkage prediction model.

[0011] Furthermore, the specific logic for the control unit to dynamically adjust the cooling rate is as follows: The welding speed, welding current and welding voltage parameters of the current layer are collected in real time to calculate the dynamic line energy input. The steel plate thickness and joint constraint degree are then substituted into the weld shrinkage prediction model to output the expected shrinkage curve during the cooling process of the current layer. Accordingly, the heating output power of the active thermal compensation zone is adjusted so that the cooling and shrinkage curve of the active thermal compensation zone is dynamically matched with the expected shrinkage curve.

[0012] The present invention also provides a rapid docking and installation system for large-span steel structures to realize the above-mentioned process, comprising: A flexible support frame is placed at the bottom of the steel structure section to be connected to provide the steel structure with the freedom to slide axially. The heating device is wrapped around the outside of the main load-bearing component of the active thermal compensation zone; A displacement sensor is bridging the mating end face to acquire the measured value of the closing gap and the real-time displacement feedback signal. The control unit is communicatively connected to the heating device and the displacement sensor, respectively. The control unit is configured to control the output power of the heating device based on the measured value of the closing gap, so as to drive the mating end face to close and maintain a controlled compensation state in the subsequent welding stage.

[0013] Furthermore, the heating device is a flexible electromagnetic induction heating blanket or a heating coil; The system also includes a temperature sensor disposed on the surface of the active thermal compensation zone. The temperature sensor is communicatively connected to the control unit and is used to provide real-time temperature feedback signals.

[0014] Compared with existing construction methods that use mechanical forced pulling or local weld preheating correction, this invention achieves a dual compensation control mechanism in both the spatial and temporal domains by combining remote thermally induced linear drive with time-dimensional synchronous cooling and contraction control. Specifically: 1. This invention sets an active thermal compensation zone on the main load-bearing component far from the weld and performs controlled heating, so that the steel structure itself generates axial thermal expansion displacement to drive the butt joint end face to close. This replaces the traditional method of mechanically forcibly pulling together using jacks, tie rods or rigid clamps, thus avoiding the problems of initial assembly stress and local stress concentration caused by external force forced cold pulling from the source.

[0015] 2. This invention implements synchronous cooling control during the welding filling and capping stages, and uses the cold shrinkage deformation of the far-end compensation zone to offset the thermal shrinkage deformation of the weld zone on the time axis, so that the cold shrinkage deformation of the far-end compensation zone matches the thermal shrinkage deformation of the weld zone on the time dimension, thereby reducing the additional constraint effect of welding shrinkage on the overall structure, reducing post-weld residual stress and deformation accumulation, and significantly reducing the final residual stress level of the joint.

[0016] 3. By setting the active thermal compensation zone in the axial section 1.5m to 5.0m away from the weld, the present invention forms a spatially misaligned isolation structure between the thermal displacement compensation zone and the welding heat-affected zone, which not only ensures sufficient thermal expansion stroke, but also avoids secondary thermal effects on the metallographic structure and mechanical properties of the weld and its adjacent areas.

[0017] 4. By adopting an external bridging displacement monitoring method, the present invention avoids the closed trajectory of the closing gap by means of the measurement path, thus avoiding physical interference during the gap reduction process and ensuring the continuity of displacement data acquisition and the safety of the measuring device.

[0018] 5. This invention provides axial sliding freedom through a flexible jig and works in conjunction with a thermal expansion compensation mechanism, so that the components are in a low-constraint state during the assembly process, thereby reducing the reliance on large rigid tooling equipment and improving the overall linear consistency and geometric accuracy of the structure after docking. Attached Figure Description

[0019] Figure 1 This is a flowchart illustrating the process steps of the present invention. Figure 2 This is a schematic diagram of the overall layout of the large-span steel structure active docking according to the present invention.

[0020] In the diagram: 10, steel structure to be connected; 20, flexible jig; 30, active thermal compensation zone; 40, heating device; 50, displacement sensor; 60, temperature sensor; 70, control unit. Detailed Implementation

[0021] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0022] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0023] like Figure 1 and Figure 2 As shown, in the closure construction of large-span steel structures in building engineering, the steel structure 10 to be connected is hoisted to a predetermined elevation and supported on a flexible support frame 20. The top of the flexible support frame 20 is equipped with rollers or PTFE sliding plates, allowing the steel structure 10 to have the freedom to slide horizontally along the axial direction. For example... Figure 1 As shown in step S1, in the initial state, a naturally formed closing gap D exists between the end faces of the two steel structures 10 to be connected. At this time, the value of the closing gap D is measured using a displacement sensor 50, and the initial ambient temperature T0 of the steel structures 10 to be connected is recorded. Figure 2 As shown, the displacement sensor 50 is externally mounted across the gap D. Its main body is fixed to the upper flange surface of one section of the steel structure 10 to be connected, and its anchor point or reflective target is fixed to the corresponding surface of the other section of the steel structure 10 to be connected. This external mounting method, which spans the closing gap D, ensures that the displacement sensor 50 will not physically interfere with the end face or be damaged by compression during the gradual closing of the gap.

[0024] like Figure 1 As shown in step S2, after determining the closing gap D, an active thermal compensation zone 30 is defined on the stressed chord within a range of 1.5m to 5.0m from the weld to be butt-welded. Figure 2As shown, the selection of the predetermined axial distance range is based on the verification results of the balance between thermodynamic coupling effect and structural stability. If the distance is less than 1.5m, the temperature field generated by the active thermal compensation zone 30 will overlap with the local heat-affected zone generated by the welding operation, resulting in a slow cooling rate at the weld edge, which can easily cause coarsening of metal grains and a decrease in joint impact toughness. Moreover, the superposition of heat will interfere with the accuracy of displacement measurement. If the distance is greater than 5.0m, the axial thrust generated by thermal expansion will increase the risk of instability due to the slenderness ratio of the component during long-distance transmission, and will cause a significant time lag in the thermal response, making the dynamic coordinated cooling compensation in step S5 unable to match the micro-shrinkage of the weld in real time.

[0025] The effective length of the active thermal compensation zone 30 is selected as L. The control unit 70 is configured according to the formula... The target temperature rise ΔT is calculated, where D is the measured closing gap, α is the linear expansion coefficient of the steel used in the steel structure 10 to be connected, and L is the preset length of the active thermal compensation zone 30. The physical principle of this formula is to increase the temperature of the steel to induce controlled axial thermal expansion, and use the thermal expansion displacement as a driving force to close the closing gap D.

[0026] As a specific example, if the measured closing gap D is 8mm, the selected active thermal compensation zone 30 has a length L of 3m, and the coefficient of linear expansion of the steel α is taken as... The calculated target temperature rise ΔT is approximately 222.2℃. If the initial ambient temperature T0 is 20℃, the target heating temperature is 242.2℃. This temperature is much lower than the phase transformation temperature at which the steel undergoes microstructural changes (usually above 723℃), thus achieving gap closure while ensuring the stability of the material's mechanical properties.

[0027] like Figure 1 As shown in step S3, and in combination with Figure 2 The control unit 70 activates the heating device 40, which is wrapped around the active thermal compensation zone 30. The heating device 40 uses a flexible electromagnetic induction heating blanket, which can closely adhere to the surface of the component to provide a uniform thermal field. During the heating process, the temperature sensor 60, located on the surface of the active thermal compensation zone 30, feeds back the real-time temperature signal to the control unit 70. The control unit 70 combines the temperature signal and the feedback displacement signal from the displacement sensor 50 to dynamically adjust the output power of the heating device 40. When the displacement sensor 50 indicates that the closing gap D has decreased to zero and the end faces are completely fitted, the control unit 70 automatically locks the current heating power, maintaining the active thermal compensation zone 30 at a constant temperature of T0+ΔT. At this time, the active thermal compensation zone 30 acts as a macroscopic linear actuator, converting thermal energy into mechanical expansion energy, achieving rapid end face docking while reducing mechanical forced cold-pulling stress.

[0028] like Figure 1As shown in step S4, under the condition of maintaining a constant temperature in the active heat compensation zone 30 and keeping the butt joint surfaces in controlled contact, the construction personnel perform root pass welding on the butt weld. After the root pass welding is completed, proceed as follows: Figure 1 The welding process, shown in step S5, involves filler and capping welding. During this stage, the cooling of the weld pool causes significant volume shrinkage, leading to tensile stress. To suppress this stress, the control unit 70 uses sensors to collect welding current, welding voltage, and welding speed parameters in real time. It calculates the dynamic linear energy input during the welding process and, combined with the steel plate thickness and joint constraint, inputs this data into a preset weld shrinkage prediction model, outputting the expected shrinkage deformation at the current time t. .

[0029] Based on the prediction results, and referring to Figure 2 The control unit 70 coordinates with the heating device 40 to reduce its output power, guiding the active thermal compensation zone 30 to begin cooling. During the cooling process, the active thermal compensation zone 30 undergoes axial contraction, and its contraction follows a specific pattern. ,in Let t be the amount of temperature drop of the active thermal compensation zone 30 relative to the lock temperature. The control unit 70 adjusts the cooling rate to synchronize the cooling contraction of the active thermal compensation zone 30. The expected shrinkage deformation of the weld zone Phase dynamic matching. This time-dimensional coordinated control enables dynamic adjustment of stress fluctuations, thereby significantly reducing the final residual stress of the joint. Cooling control is stopped once the weld capping is completely completed and the active thermal compensation zone 30 synchronously returns to the initial ambient temperature T0. Finally, after the structure has completely cooled and passed non-destructive testing, the flexible formwork 20 is removed, completing the system conversion of the large-span steel structure.

[0030] In other preferred embodiments, the specific location of the active thermal compensation zone 30 described in this invention is not limited to the truss chord; it can also be placed on the beam web, lower chord, or connecting members, depending on the specific structural stress characteristics and on-site construction space. The heating device 40 is not limited to electromagnetic induction; it can also be a resistance heating blanket, far-infrared heating plate, or flexible ceramic heater, depending on the on-site power conditions. In addition to the aforementioned wire-type displacement gauge, the displacement sensor 50 can be replaced with a high-precision laser displacement gauge or an LVDT linear displacement gauge, as long as its measurement range and resolution meet the high-precision closing requirements. Furthermore, the specific numerical parameters in this embodiment (such as gap D, compensation length L, and temperature rise ΔT) are only set to illustrate the process principle. In actual engineering applications, those skilled in the art can make adaptive adjustments based on the specific steel material, ambient temperature, and structural span. Any equivalent transformations, simple substitutions, or fine-tuning of parameters made based on the technical concept of this invention fall within the protection scope of this invention.

[0031] In summary, this invention, by setting an active thermal compensation zone 30 at the far end of the steel structure 10 to be joined, utilizes the controlled thermal expansion displacement generated by the heating device 40 to drive the closing of the joining end faces, replacing the traditional mechanical forced closing method and avoiding initial stress during the assembly stage from the source. A feedback control system composed of displacement sensor 50, temperature sensor 60, and control unit 70 enables digital monitoring and adjustment of the entire closing process. During the welding stage, the dynamic cooling and contraction mechanism of the active thermal compensation zone 30 achieves the effect of offsetting weld shrinkage deformation over time, significantly suppressing the generation of residual stress in the overall structure. Combined with the low-constraint sliding conditions provided by the flexible jig 20, this invention improves the accuracy and safety of the closing installation of large-span steel structures, ensuring the final linear quality of the structure.

[0032] This specific embodiment is merely an explanation of the present invention and is not intended to limit the invention. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they are within the scope of the claims of the present invention.

Claims

1. A rapid connection and installation process for large-span steel structures used in building construction, characterized in that, Includes the following steps: S1. Place the steel structure section to be connected on the flexible jig, keep it in a natural position, and obtain the measurement value of the closing gap between the docking end faces; S2. Define the active thermal compensation zone in the non-welding zone of the main load-bearing component at a predetermined axial distance from the weld to be butted; S3. The active thermal compensation zone is heated in a controlled manner to generate axial thermal expansion displacement, thereby pushing the mating end faces to move relative to each other until the closing gap is closed; S4. While maintaining controlled compensation in the active thermal compensation zone, perform root pass welding on the mating end face; S5. During the weld filling and cover welding stages, the cooling rate of the active heat compensation zone is dynamically adjusted so that the synchronous cooling shrinkage of the active heat compensation zone in the time dimension is used to offset or reduce the welding shrinkage of the butt joint surface, thereby effectively suppressing the overall residual stress of the structure.

2. The rapid connection and installation process for large-span steel structures in building engineering according to claim 1, characterized in that: In step S2, the range of the predetermined axial distance is defined as: 1.5m to 5.0m along the axial distance of the component from the weld to be butted; and the maximum temperature for heating the active thermal compensation zone is limited to being lower than the metallographic phase transformation temperature of the large-span steel structure base material.

3. The rapid connection and installation process for large-span steel structures in building engineering according to claim 1, characterized in that: In step S3, the control unit determines the target temperature rise based on the measured value of the closing gap, the linear expansion coefficient of the main force-bearing component, and the length of the active thermal compensation zone; The control unit uses the target temperature rise as a reference and dynamically adjusts the heating power in conjunction with the real-time displacement feedback signal until the gap is completely closed and then locks the heating state.

4. The rapid connection and installation process for large-span steel structures in building engineering according to claim 3, characterized in that: In steps S1 and S3, an external bridging displacement sensor is used to obtain the measured value of the closing gap and the real-time displacement feedback signal. The external bridging displacement sensor is installed as follows: its main body box is installed on the outer surface of the steel structure on one side of the docking end face, its fixed anchor point or reflective target is installed on the outer surface of the steel structure on the other side of the docking end face, and its measurement connection line or optical path crosses the outside of the closing gap to avoid physical interference of the sensor when the closing gap is closed.

5. The rapid connection and installation process for large-span steel structures in building engineering according to claim 1, characterized in that: In step S5, the control unit dynamically adjusts the cooling rate of the active thermal compensation zone based on the welding heat input parameters and the preset weld shrinkage prediction model.

6. The rapid connection and installation process for large-span steel structures in building engineering according to claim 5, characterized in that: The specific logic for the control unit to dynamically adjust the cooling rate is as follows: The welding speed, welding current and welding voltage parameters of the current layer are collected in real time to calculate the dynamic line energy input. The steel plate thickness and joint constraint degree are then substituted into the weld shrinkage prediction model to output the expected shrinkage curve during the cooling process of the current layer. Accordingly, the heating output power of the active thermal compensation zone is adjusted so that the cooling and shrinkage curve of the active thermal compensation zone is dynamically matched with the expected shrinkage curve.

7. A rapid docking and installation system for large-span steel structures to implement the process described in any one of claims 1 to 6, characterized in that, include: A flexible support frame is placed at the bottom of the steel structure section to be connected to provide the steel structure with the freedom to slide axially. The heating device is wrapped around the outside of the main load-bearing component of the active thermal compensation zone; A displacement sensor is bridging the mating end face to acquire the measured value of the closing gap and the real-time displacement feedback signal. The control unit is communicatively connected to the heating device and the displacement sensor, respectively. The control unit is configured to control the output power of the heating device based on the measured value of the closing gap, so as to drive the mating end face to close and maintain a controlled compensation state in the subsequent welding stage.

8. The rapid docking and installation system for large-span steel structures according to claim 7, characterized in that: The heating device is a flexible electromagnetic induction heating blanket or a heating coil; The system also includes a temperature sensor disposed on the surface of the active thermal compensation zone. The temperature sensor is communicatively connected to the control unit and is used to provide real-time temperature feedback signals.

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