Full penetration welding process for intersecting line of flat-chordal pipe of half-through steel pipe concrete composite arch bridge

Abstract

This invention relates to a full-penetration welding process for the intersection line of the connecting pipes in a mid-span steel-concrete composite arch bridge, comprising the following steps: dividing the connecting pipe into three sections: a first joint pipe, a main connecting pipe, and a second joint pipe; welding the inner and outer sides of the intersection line of the first and second joint pipes in the factory; performing non-destructive testing on the welds after welding; transporting the main arch chord, web members, and the main connecting pipe to the construction site, and assembling the main arch chord and web members to form a truss; welding both sides of the main connecting pipe to the first and second joint pipes respectively, and performing non-destructive testing on the welds after welding. The welding method of this invention, by dividing the connecting pipe into a three-section structure (first joint pipe, main connecting pipe, and second joint pipe), and welding the first and second joint pipes to the truss first, enables welding of both the inner and outer sides of the intersection line of the connecting pipe and the truss, achieving full-penetration welding of the intersection line of the connecting pipes in a steel-concrete composite arch bridge.

Description

Technical Field

[0001] This invention relates to the field of steel structure bridge manufacturing, and in particular to a full penetration welding process for the intersecting lines of the horizontal connecting pipes in a mid-span steel-concrete composite arch bridge. Background Technology

[0002] A steel-concrete composite arch bridge is a type of bridge that uses steel tubes filled with concrete to form a composite structure. Its core principle is to utilize the confinement effect of the steel tubes on the concrete, subjecting the concrete to triaxial compression and significantly improving its compressive strength. This bridge type offers technical advantages such as large span capacity, convenient construction, and aesthetically pleasing design.

[0003] Currently, in the process of constructing steel-concrete composite arch bridges, the horizontal connecting pipe, as a connector used to connect the arch ribs, enhances the stability of the arch ribs and ensures the integrity and safety of the bridge structure. It is also important for the fixed support pipes.

[0004] like Figure 1 The diagram shows a horizontal connecting pipe structure for an arch bridge, in which two trusses are connected by four horizontal connecting pipes. In this structure, when the horizontal connecting pipes are welded to the two trusses, the horizontal connecting pipe is a single pipe structure with intersecting lines on both sides. The traditional welding method is to weld the intersecting lines to the outside of the horizontal connecting pipe and the truss, which cannot guarantee full penetration of the intersecting lines, and defects are easily caused at the root. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a welding process for the intersecting pipes of a mid-span steel-concrete composite arch bridge that can achieve full penetration welding of the intersecting pipes of the steel-concrete composite arch bridge.

[0006] To solve the above-mentioned technical problems, the technical solution of the present invention is: a full penetration welding process for the intersecting lines of the horizontal connecting pipes of a mid-span steel-concrete composite arch bridge, the innovation of which is: including the following steps: S1: First, the horizontal connecting pipe is divided into three sections, namely the first joint pipe, the horizontal connecting pipe main pipe and the second joint pipe, which are distributed in sequence. The first joint pipe and the second joint pipe are respectively connected to two truss segments. The truss segment includes a pair of main arch chords and several web members in the middle for connection. S2: Prepare the required main arch chord, web members, first joint pipe, second joint pipe, and main horizontal connecting pipe respectively; S3: Weld the first joint pipe and the second joint pipe to the two main arch chords in the factory. When welding, weld the inner and outer sides of the intersection line of the first joint pipe and the second joint pipe respectively. S4: After welding is completed, non-destructive testing is performed on the weld. S5: Then, transport the main arch chord, web members and horizontal connecting pipe to the construction site, and assemble the main arch chord and web members to form a truss. S6: Finally, weld the two sides of the main pipe of the flat connector to the first connector pipe and the second connector pipe respectively, and perform non-destructive testing on the weld after welding to complete the processing.

[0007] Furthermore, in step S3, when welding the inner and outer welds of the intersection line, the inner weld of the intersection line is welded first, then the outer weld of the intersection line is air-gouged and ground evenly, and finally the outer weld of the intersection line is welded.

[0008] Furthermore, in step S3, when welding the intersecting line weld, CO2 gas shielded welding is used, and the purity of CO2 gas is not less than 99.5%. The welding material is either Q345qD steel plate: T492T1-1C1A or Q420qD steel plate: T494T1-1C1A.

[0009] Furthermore, when the wall thickness of the first joint pipe and the second joint pipe is ≤30mm, Q345qD steel plate: T492T1-1C1A is selected. During welding, the preheating temperature is ≥5℃, the interpass temperature is between 5-200℃, the current for the root pass is 140±20A, the voltage is 24±2V, and the CO2 gas flow rate is 15-20L / min. For other passes, the current is 160±20A, the voltage is 26±2V, and the CO2 gas flow rate is 15-20L / min. When the wall thickness of the first and second joint pipes is greater than 30mm, Q420qD steel plate (T494T1-1C1A) should be selected. During welding, the preheating temperature should be between 80-120℃, the preheating range should be ≥100mm, the interpass temperature should be between 80-200℃, the current for the root pass should be 140±20A, the voltage should be 24±2V, and the CO2 gas flow rate should be 15-20L / min. For other passes, the current should be 160±20A, the voltage should be 26±2V, and the CO2 gas flow rate should be 15-20L / min.

[0010] Furthermore, in step S3, when performing intersecting line weld welding, the arc is started from the weld root, and then the welding proceeds symmetrically and alternately towards the weld toe.

[0011] Furthermore, when the wall thickness of the first joint pipe and the second joint pipe is ≤30mm, ultrasonic testing and magnetic particle testing of the intersection weld and the inner fillet weld of the intersection line are performed 24 hours after welding. When the wall thickness of the first joint pipe and the second joint pipe is >30mm, ultrasonic testing and magnetic particle testing of the intersection weld and the inner fillet weld of the intersection line are performed 48 hours after welding.

[0012] The advantages of this invention are as follows: The welding method of this invention divides the horizontal connecting pipe into a three-section structure of a first joint pipe, a horizontal connecting pipe main pipe and a second joint pipe. The first joint pipe and the second joint pipe are welded to the truss plate first, so that the horizontal connecting pipe can be welded on both the inner and outer sides of the intersection line of the horizontal connecting pipe and the truss plate. This achieves full penetration of the welding of the horizontal connecting pipe intersection line of the steel pipe composite arch bridge and avoids defects at the weld root.

[0013] Based on the above welding method, the problem of full penetration welding of the intersecting line in traditional welding methods is solved, which enhances the strength of the bridge structure, improves the quality of the product weld and the first-pass yield. The bridge structure prepared by the above method has the arch ribs forming a spatial truss structure through high-precision intersecting line welding, which can withstand the dynamic load of high-speed trains and the self-weight of the bridge, ensuring the overall stability of the bridge (span-to-rise ratio of 1 / 4) and its wind and earthquake resistance. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the arch bridge horizontal connecting pipe structure of the present invention. Detailed Implementation

[0015] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided below.

[0016] The full penetration welding process for the intersecting lines of the horizontal connecting pipes in the mid-span steel-concrete composite arch bridge of the present invention is achieved through the following steps: S1: First, as Figure 1 As shown, the horizontal connecting pipe is divided into three sections, namely the first joint pipe 3, the main horizontal connecting pipe 4, and the second joint pipe 5, which are distributed in sequence. The first joint pipe 3 and the second joint pipe 4 are respectively connected to two truss segments. The truss segments include a pair of main arch chords 1 and several web members 2 in the middle for connection. The intersection lines on both sides of the horizontal connecting pipe are the intersection lines of the first joint pipe 3 and the second joint pipe 5 on the side away from the main horizontal connecting pipe 4.

[0017] S2: Prepare the required main arch chord 1, web member 2, first joint pipe 3, second joint pipe 5, and horizontal connecting pipe main 4 respectively.

[0018] S3: In the factory, the first joint pipe 3 and the second joint pipe 5 are first welded to the two main arch chords 1. When welding, the inner and outer sides of the intersection line of the first joint pipe 3 and the second joint pipe 5 need to be welded. When welding the inner and outer sides of the intersection line, the inner side of the intersection line is welded first. Then, the outer side of the intersection line is gouged and ground evenly. Finally, the outer side of the intersection line is welded. When welding the intersection line, start the arc from the weld root and then weld symmetrically and alternately towards the weld toe.

[0019] When performing intersecting line welds, CO2 gas shielded welding shall be used, and the purity of CO2 gas shall not be less than 99.5%. The welding materials shall be either Q345qD steel plate: T492T1-1C1A or Q420qD steel plate: T494T1-1C1A.

[0020] The specific welding materials to be selected are as follows: If the wall thickness of the first joint pipe 3 and the second joint pipe 5 is ≤30mm, Q345qD steel plate: T492T1-1C1A should be selected. When welding, a flame or far-infrared heater should be used for preheating. The preheating temperature should be ≥5℃, and the interpass temperature should be between 5-200℃. The temperature measuring point should be 30~50mm away from the weld. The current for the root pass is 140±20A, the voltage is 24±2V, and the CO2 gas flow rate is 15-20L / min. The current for other passes is 160±20A, the voltage is 26±2V, and the CO2 gas flow rate is 15-20L / min. If the wall thickness of the first joint pipe 3 and the second joint pipe 5 is greater than 30mm, Q420qD steel plate (T494T1-1C1A) should be selected. During welding, a flame or far-infrared heater should be used for preheating. The preheating temperature should be between 80-120℃, and the preheating range should be ≥100mm from the weld and both sides. The interpass temperature should be between 80-200℃. The temperature measuring point should be 30-50mm away from the weld. The current for the root pass should be 140±20A, the voltage should be 24±2V, and the CO2 gas flow rate should be 15-20L / min. The current for other passes should be 160±20A, the voltage should be 26±2V, and the CO2 gas flow rate should be 15-20L / min.

[0021] Before welding, confirm that the welding wire and welding rod are correct. Oil, rust and other dirt on the welding wire must be cleaned. The purity of CO2 gas should not be less than 99.5%. A protective gas flow meter should be connected to the gas line during welding (when using bottled CO2 gas, the flow meter should be able to heat).

[0022] Gas-shielded semi-automatic welding equipment includes models such as KRⅡ500 and YD-500 FR1. All of the above welding equipment uses DC reverse polarity connection.

[0023] S4: After welding is completed, non-destructive testing is performed on the weld.

[0024] When the wall thickness of the first joint pipe 3 and the second joint pipe 5 is ≤30mm, ultrasonic testing and magnetic particle testing of the intersection weld and the inner fillet weld of the intersection line shall be carried out 24 hours after welding. When the wall thickness of the first joint pipe 3 and the second joint pipe 5 is >30mm, ultrasonic testing and magnetic particle testing of the intersection weld and the inner fillet weld of the intersection line shall be carried out 48 hours after welding.

[0025] S5: Then, transport the main arch chord 1, web members 2 and horizontal connecting pipe 4 to the construction site, and assemble the main arch chord 1 and web members 2 to form a truss.

[0026] S6: Finally, weld the two sides of the main pipe 4 to the first joint pipe 3 and the second joint pipe 5 respectively, and perform non-destructive testing on the weld after welding to complete the processing.

[0027] For the welding between the main pipe 4 and the first joint pipe 3 and the second joint pipe 5, CO2 gas shielded welding is also used. The selection of welding materials and welding parameters are the same as those in step S3, and will not be described in detail here. When inspecting after welding, if the pipe wall thickness is ≤30mm, ultrasonic testing of the butt weld of the steel pipe is carried out 24 hours after welding. If the pipe wall thickness of the first joint pipe 3 and the second joint pipe 5 is >30mm, ultrasonic testing of the butt weld of the steel pipe is carried out 48 hours after welding.

[0028] During the welding process described above, the ambient temperature should not be lower than 5℃ and the ambient humidity should not be higher than 80%. When the ambient temperature is lower than 5℃ and the ambient humidity is higher than 80%, necessary preheating measures should be taken before welding. The wind force in the welding area should not exceed level 5, and the wind speed in the gas shielded welding work area should not exceed 2m / s; otherwise, windproof canopies should be used for local wind protection. Construction should generally be stopped in rainy or snowy weather. If special circumstances arise, appropriate measures should be taken before welding can proceed.

[0029] Before assembling all welds, clean the rust, oil, and pre-coated primer within a 20-30mm range on both sides of the weld to expose the metallic luster.

[0030] Before welding, the slag on the surface of the tack weld should be removed, and the cleanliness of the area to be welded should be checked.

[0031] During welding, it is strictly forbidden to strike an arc on non-welding parts of the base material. After welding, the slag on the weld surface and the spatter on both sides should be cleaned.

[0032] No impact or vibration is allowed during welding or weld cooling.

[0033] For double-sided welding that requires full penetration, in order to ensure full penetration, when the back side is cleaned with carbon arc gouging, it is necessary to grind it smooth and even with a grinding wheel before welding.

[0034] When performing multi-layer, multi-pass welding, the slag from the previous weld should be thoroughly cleaned and the weld should be inspected for cracks or other welding defects before continuing the welding process.

[0035] The welding method of the present invention divides the horizontal connecting pipe into a three-section structure: a first joint pipe, a main horizontal connecting pipe, and a second joint pipe. The first joint pipe and the second joint pipe are welded to the truss plate first, thereby enabling welding of both the inner and outer sides of the horizontal connecting pipe at the intersection line of the truss plate. This achieves full penetration welding of the horizontal connecting pipe intersection line of the steel pipe composite arch bridge and avoids defects at the weld root.

[0036] Based on the above welding method, the problem of full penetration welding of the intersecting line, which is a problem in traditional welding methods, is solved, enhancing the strength of the bridge structure, improving the quality of the product weld and the first-pass yield. The bridge structure prepared by the above method has the arch ribs forming a spatial truss structure through high-precision intersecting line welding, which can withstand the dynamic load of high-speed trains and the self-weight of the bridge, ensuring the overall stability of the bridge (span-to-rise ratio of 1 / 4) and its wind and seismic resistance. It can be applied to the preparation of 400km / h mid-span steel-concrete composite arch bridges.

[0037] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A full penetration welding process for the intersecting lines of the horizontal connecting pipes in a mid-span steel-concrete composite arch bridge, characterized in that: Includes the following steps: S1: First, the horizontal connecting pipe is divided into three sections, namely the first joint pipe, the horizontal connecting pipe main pipe and the second joint pipe, which are distributed in sequence. The first joint pipe and the second joint pipe are respectively connected to two truss segments. The truss segment includes a pair of main arch chords and several web members in the middle for connection. S2: Prepare the required main arch chord, web members, first joint pipe, second joint pipe, and main horizontal connecting pipe respectively; S3: Weld the first joint pipe and the second joint pipe to the two main arch chords in the factory. When welding, weld the inner and outer sides of the intersection line of the first joint pipe and the second joint pipe respectively. S4: After welding is completed, non-destructive testing is performed on the weld. S5: Then, transport the main arch chord, web members and horizontal connecting pipe to the construction site, and assemble the main arch chord and web members to form a truss. S6: Finally, weld the two sides of the main pipe of the flat connector to the first connector pipe and the second connector pipe respectively, and perform non-destructive testing on the weld after welding to complete the processing.

2. The full penetration welding process for the intersecting lines of the horizontal connecting pipes in a mid-span steel-concrete composite arch bridge according to claim 1, characterized in that: In step S3, when welding the inner and outer welds of the intersection line, the inner weld of the intersection line is welded first, then the outer weld of the intersection line is air-gouged and ground evenly, and finally the outer weld of the intersection line is welded.

3. The full penetration welding process for the intersecting lines of the horizontal connecting pipes in a mid-span steel-concrete composite arch bridge according to claim 1, characterized in that: In step S3, when welding the intersecting line weld, CO2 gas shielded welding is used, and the purity of CO2 gas is not less than 99.5%. The welding material is either Q345qD steel plate: T492T1-1C1A or Q420qD steel plate: T494T1-1C1A.

4. The full penetration welding process for the intersecting lines of the horizontal connecting pipes in a mid-span steel-concrete composite arch bridge according to claim 3, characterized in that: When the wall thickness of the first joint pipe and the second joint pipe is ≤30mm, Q345qD steel plate: T492T1-1C1A is selected. During welding, the preheating temperature is ≥5℃, the interpass temperature is between 5-200℃, the current for the root pass is 140±20A, the voltage is 24±2V, and the CO2 gas flow rate is 15-20L / min. For other passes, the current is 160±20A, the voltage is 26±2V, and the CO2 gas flow rate is 15-20L / min. When the wall thickness of the first and second joint pipes is greater than 30mm, Q420qD steel plate (T494T1-1C1A) should be selected. During welding, the preheating temperature should be between 80-120℃, the preheating range should be ≥100mm, the interpass temperature should be between 80-200℃, the current for the root pass should be 140±20A, the voltage should be 24±2V, and the CO2 gas flow rate should be 15-20L / min. For other passes, the current should be 160±20A, the voltage should be 26±2V, and the CO2 gas flow rate should be 15-20L / min.

5. The full penetration welding process for the intersecting lines of the horizontal connecting pipes in a mid-span steel-concrete composite arch bridge according to claim 1, characterized in that: In step S3, when welding the intersecting line weld, the arc is started from the weld root, and then the welding is carried out symmetrically and alternately towards the weld toe.

6. The full penetration welding process for the intersecting lines of the horizontal connecting pipes in a mid-span steel-concrete composite arch bridge according to claim 1, characterized in that: When the wall thickness of the first joint pipe and the second joint pipe is ≤30mm, ultrasonic testing and magnetic particle testing of the intersection weld and the inner fillet weld of the intersection line shall be carried out 24 hours after welding. When the wall thickness of the first joint pipe and the second joint pipe is >30mm, ultrasonic testing and magnetic particle testing of the intersection weld and the inner fillet weld of the intersection line shall be carried out 48 hours after welding.

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