A suspended printing method for reinforced concrete bridges and construction equipment.

Abstract

This invention relates to a suspended printing method and construction device for reinforced concrete bridges. The bridge comprises piers, variable cross-section beams, bridge decks, and longitudinal and transverse reinforcing bars. The bridge piers are printed first, followed by the variable cross-section beams and bridge decks. The variable cross-section beams are printed layer by layer from bottom to top, with each layer increasing in length and height, and longitudinal and transverse reinforcing bars laid between layers. The construction device includes a track system, a frame system, a formwork system, and a printing system. The frame system provides a working platform for the formwork and printing systems. The formwork system uses a suspended formwork to support the suspended printing of the variable cross-section beams. The printing system uses a robotic arm to install the reinforcing bars and an extrusion head to extrude and stack the printed concrete. This invention provides a variable cross-section beam bridge that can be directly printed layer by layer, and uses a suspended formwork system to achieve suspended printing of reinforced concrete. The process is simple and suitable for on-site construction.

Description

Technical Field

[0001] This invention relates to the technical field of 3D printing construction in civil engineering, and in particular to a suspended printing of reinforced concrete bridges and construction equipment, as well as a printing method. Background Technology

[0002] The technology for 3D printing bridges is developing rapidly. Existing 3D printed bridges mainly include precast concrete arch bridges, precast prestressed beam bridges, and all-steel structure bridges. Most of these bridges are printed in a factory and then assembled on-site using scaffolding. Reinforced concrete bridges that can be printed on-site are very rare, mainly for two reasons:

[0003] 1. Existing printed bridge structures are limited to arch bridges and prestressed beam bridges. Both of these structures are subjected to large compressive stress in their cross-sections. However, the lateral bearing capacity of layered printed concrete is relatively small. Therefore, it is necessary to first print the bridge cross-section on a plane, then rotate it 90 degrees and assemble it. It is not possible to print it directly on site.

[0004] 2. Concrete cannot be printed in mid-air like steel. On-site bridge construction requires formwork and supports. Once the supports and formwork are erected, concrete can be poured to construct the bridge, which does not demonstrate the effectiveness of 3D printing.

[0005] In summary, suitable concrete bridge structural forms for 3D printing need to be proposed, and corresponding construction methods with few or no supports need to be developed. Summary of the Invention

[0006] The present invention aims to address the shortcomings of the prior art by providing a suspended printing method for reinforced concrete bridges, construction equipment, and printing.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A suspended 3D-printed reinforced concrete bridge includes two piers arranged along the length of the bridge. Each pier includes several layers of pier units connected from top to bottom. Each pier unit is composed of several 3D-printed concrete single layers. The top of each pier unit is embedded with longitudinal and transverse steel bars, and vertical steel bars are inserted inside the pier.

[0009] The bridge pier is equipped with a variable cross-section beam, which includes several layers of support beams arranged from top to bottom. The length of the several layers of support beams extends to both sides from bottom to top. Each layer of support beams is composed of several 3D printed concrete single layers. A steel mesh is laid on the top of each layer of support beams. The steel mesh is welded and fixed by the transverse steel bars and longitudinal steel bars of the support beam.

[0010] The bridge deck is supported by the top of the two variable cross-section beams. The bridge deck is composed of several 3D printed concrete single layers and contains several longitudinal steel bars arranged along the length of the bridge.

[0011] Vertical reinforcing bars are inserted inside the variable cross-section beam.

[0012] The bridge pier is 1m long, 7m wide, and 2m high; the height of a single bridge pier is 10cm, and the bridge pier is composed of 20 bridge pier units; the thickness of a single 3D printed concrete layer is 1cm, and a single bridge pier unit is composed of 10 3D printed concrete layers.

[0013] The variable cross-section beam is 7m wide and 3m high; the height of the supporting beam is 10cm. The variable cross-section beam consists of 30 layers of supporting beams. The length of the top layer of supporting beams is 6m and the length of the bottom layer of supporting beams is 20cm. The suspended length of each layer of supporting beams is 20cm longer than that of the layer below, and 10cm longer on each side.

[0014] The above-mentioned construction device for suspended printed reinforced concrete bridge includes a track system, a frame system, a formwork system, and a printing system;

[0015] The track system consists of two parallel tracks, which are laid out on both sides of the bridge's length.

[0016] The frame system is a support frame welded together by two frame longitudinal beams and two frame transverse beams. There are four frame columns at the four corners of the bottom of the support frame. The bottom of the frame columns is equipped with casters, which are rolled on the track.

[0017] The formwork system includes four positioning beams installed between two frame longitudinal beams. The bottom of the positioning beams is rolled on the frame longitudinal beams by drive wheels driven by a motor. Each positioning beam is equipped with two hanging rods, which are connected to a winch. A suspended formwork is hung between the four hanging rods of every two positioning beams. The suspended formwork includes stepped suspended formwork and flat suspended formwork. The stepped suspended formwork includes three layers of formwork, which extend outwards from bottom to top. The width of each layer of formwork is the same as the width of the support beam, and the height of each layer of formwork is the same as the height of the support beam.

[0018] The printing system includes rollers mounted on the frame beams, which are driven by motors. The rollers are connected to vertical rods, and a guide beam that moves up and down is installed between the two vertical rods via a motor, gears, and chains. A movable robotic arm with a concrete extrusion head and a movable robotic arm with a rebar gripper are mounted on the guide beams. Both the movable robotic arm with the concrete extrusion head and the movable robotic arm with the rebar gripper are driven by motors to move the rotating wheels.

[0019] Each layer of the suspended formwork is 7m wide, 10cm high, and 20cm long.

[0020] The printing method for the above-mentioned suspended printing construction device for reinforced concrete bridges includes the following specific steps:

[0021] S1. The frame system is fixed in position. The bridge piers are printed. A mobile robotic arm with a concrete extrusion head prints bridge pier units in layers. Each bridge pier unit is printed from 10 1cm thick 3D printed concrete single layers. After each layer of bridge pier unit is printed, a mobile robotic arm with a steel bar gripper grabs the longitudinal and transverse steel bars and embeds them on the top of the bridge pier unit to toughen it. After printing five layers of bridge pier units, the mobile robotic arm with a steel bar gripper grabs the vertical steel bars and inserts them into the interior of the five layers of bridge pier units to enhance the bending resistance of the bridge piers.

[0022] S2. The moving positioning beam fixes the position of the stepped suspended formwork, the lifting rods fix the height of the stepped suspended formwork, and the height of the four lifting rods is adjusted to ensure that the stepped suspended formwork is horizontal.

[0023] S3. The mobile robotic arm with a steel bar gripper grabs the connected steel mesh and places it on the installed bridge piers and stepped formwork. The mobile robotic arm with a concrete extrusion head moves longitudinally on the guide beam and laterally on the frame beam to print the concrete of the supporting beam. When the height is not sufficient, the guide beam slides upward along the vertical bar to change the operating height.

[0024] S4. The three-layer support beam is a single section. After each section is printed, the stepped formwork moves 30cm to each side along the longitudinal direction of the bridge. At the same time, the height of the stepped formwork is raised by 30cm to print the next section of concrete.

[0025] S5. After the variable cross-section beam is printed, replace the flat plate formwork and print the concrete of the bridge deck, thus completing the printing of the entire bridge.

[0026] The beneficial effects of this invention are: this invention provides a variable cross-section beam bridge that can be directly printed in layers, and the use of a suspended formwork system realizes the suspended printing of reinforced concrete, which is simple in process and suitable for on-site construction. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the suspended printed reinforced concrete bridge structure in this invention;

[0028] Figure 2 This is a schematic diagram of the structure of the two bridge piers in this invention;

[0029] Figure 3 This is a structural schematic diagram of the two bridge piers and two variable cross-section beams in this invention;

[0030] Figure 4 This is a schematic diagram of the longitudinal reinforcement bars of the bridge deck erected on two variable cross-section beams in this invention;

[0031] Figure 5 This is a schematic diagram of the suspended printing reinforced concrete bridge construction device of the present invention;

[0032] Figure 6 This is a schematic diagram of the construction device for printing reinforced concrete bridges using a suspended printing method in this invention, when printing the first pier and the variable cross-section beam.

[0033] Figure 7 This is a schematic diagram of the construction device for printing reinforced concrete bridges using a suspended printing method in this invention, when printing the second pier and the variable cross-section beam.

[0034] Figure 8 This is a schematic diagram of the printing of the bridge panel after replacing the planar lifting mold in this invention;

[0035] In the diagram: 1-Pier; 2-Variable cross-section beam; 3-Bridge deck; 4-Track system; 5-Frame system; 6-Formwork system; 7-Printing system;

[0036] 11-Single bridge pier;

[0037] 21-Single supporting beam;

[0038] 41-track;

[0039] 51-Frame longitudinal beam; 52-Frame transverse beam; 53-Frame column; 54-Moving wheel;

[0040] 61-Positioning beam; 62-Lifting rod; 63-Lifting formwork;

[0041] 71-Roller; 72-Vertical rod; 73-Guide beam; 74-Mobile robotic arm with concrete extrusion head; 75-Mobile robotic arm with rebar gripper;

[0042] The following will describe in detail, with reference to the accompanying drawings, embodiments of the present invention. Detailed Implementation

[0043] The principles and features of the present invention are described below with reference to the accompanying drawings. The embodiments given are for illustrative purposes only and are not intended to limit the scope of the invention. The invention is described more specifically in the following paragraphs by way of example with reference to the accompanying drawings. The advantages and features of the invention will become clearer from the following description. It should be noted that the drawings are in a very simplified form and use non-precise proportions, and are only used to facilitate and clarify the illustration of the embodiments of the invention.

[0044] It should be noted that when a component is described as "fixed to" another component, it can be directly on the other component or may have a component in between. When a component is considered "connected to" another component, it can be directly connected to the other component or may have a component in between. When a component is considered "set on" another component, it can be directly set on the other component or may have a component in between. The terms "vertical," "horizontal," "left," "right," and similar expressions used in this document are for illustrative purposes only.

[0045] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0046] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0047] A suspended, printed reinforced concrete bridge, such as Figures 1 to 4 As shown, the bridge includes two piers 1 arranged along the length of the bridge. Each pier 1 includes several layers of pier units 11 connected from top to bottom. Each layer of pier unit 11 is composed of several 3D printed concrete single layers. The top of each layer of pier unit 11 is embedded with longitudinal and transverse steel bars. Vertical steel bars are inserted inside the pier 1.

[0048] The top of the pier 1 is equipped with a variable cross-section beam 2, which includes several layers of support beam units 21 arranged from top to bottom. The length of the several layers of support beam units 21 extends to both sides from bottom to top. Each layer of support beam unit 21 is composed of several 3D printed concrete single layers. The top of each layer of support beam unit 21 is covered with a steel mesh. The steel mesh is welded and fixed by the transverse steel bars and longitudinal steel bars of the support beam. Vertical steel bars are inserted inside the variable cross-section beam 2.

[0049] The tops of the two variable cross-section beams 2 are jointly supported by the bridge deck 3, which is composed of several 3D printed concrete single layers. The bridge deck 3 is provided with several longitudinal steel bars arranged along the length of the bridge.

[0050] A 3D bridge has two piers (1) and two corresponding variable cross-section beams (2).

[0051] First, print the bridge pier 1, then print the variable cross-section beam 2 and the bridge deck 3.

[0052] Pier 1 is 7m wide and 1m long, constructed using 3D-printed concrete. Each layer of 3D-printed concrete is 1cm thick, and ten such layers form one pier unit 11, with a thickness of 10cm. Each pier unit 11 can be reinforced with longitudinal and transverse steel bars. Pier 1 is 2m high; printing five pier units 11 increases the vertical reinforcement and enhances its bending resistance.

[0053] The variable cross-section beam 2 is printed horizontally in layers from bottom to top. Each layer of the supporting beam unit 21 has a width of 7m and a height of 10cm, with each subsequent layer increasing in height by 20cm overhang, for a total of 30 layers. This means the maximum length of the variable cross-section beam 2 is 6m, and its height is 3m. The bridge span formed by two variable cross-section beams 2 is 12m. A steel mesh is laid between the supporting beam units 21 to increase strength. The steel mesh consists of longitudinal and transverse reinforcing bars.

[0054] A bridge deck 3 is printed on top of the variable cross-section beam 2. The longitudinal reinforcement of the bridge deck 3 is arranged along the entire length of the two variable cross-section beams 2. The concrete of the bridge deck 3 needs to have higher flatness requirements.

[0055] Meanwhile, this invention provides a construction device for suspended printing of reinforced concrete bridges, such as... Figure 5 , Figure 6 As shown, the construction equipment includes a track system 4, a frame system 5, a formwork system 6, and a printing system 7.

[0056] The track system 4 includes two parallel tracks 41, which are laid out on both sides of the bridge's length and have an I-beam cross-section. In a dry environment, the track foundations for the tracks can be directly constructed by leveling the site. In a wet environment, the track foundations for the tracks can be provided by driving steel pipe piles and Bailey bridges.

[0057] The frame system 5 provides a working platform for the template system 6 and the printing system 7, and is made of welded steel sections. The frame system 5 is a support frame welded together by two longitudinal frame beams 51 and two transverse frame beams 52. There are four frame columns 53 at the four corners of the bottom of the support frame. The bottom of the frame columns 53 is equipped with moving wheels 54, which are rolled on the track 41 and can move freely along the longitudinal direction of the bridge on the track 41.

[0058] The formwork system 6 includes a positioning beam 61, a hanger 62, and a hanging form 63.

[0059] Positioning beams 61 are mounted on the longitudinal beams 51 of the frame. Each positioning beam 61 has a drive wheel at its bottom, driven by a motor, allowing it to move freely on the longitudinal beams 51. There are four positioning beams 61 on the longitudinal beams 51, each with two lifting rods 62 connected to its center. The four lifting rods 62 on the two positioning beams 61 together lift a single formwork 63. The lifting rods 62 control the height and level of the formwork 63 via a winch.

[0060] The formwork 63 includes stepped formwork and flat formwork. The stepped formwork has three layers, each 7m wide, 20cm long, and 10cm high, which is the height of one supporting beam unit 21. After the concrete of every three layers of supporting beam units 21 is printed, the stepped formwork moves 30cm to each side along the longitudinal direction of the bridge, and the height is raised by 30cm to provide support for the concrete of the next three layers of supporting beam units 21.

[0061] The printing system 7 includes rollers 71, vertical rods 72, guide beams 73, a movable robotic arm 74 with a concrete extrusion head, and a movable robotic arm 75 with a steel bar gripper.

[0062] A movable roller 71 is mounted on the frame beam 52, and the roller 71 is driven by a motor. The roller 71 is connected to the vertical rod 72, and the vertical rod 72 is connected to the guide beam 73. The guide beam 73 can slide up and down on the vertical rod 72, driven by a motor, gears, and chains. A movable robotic arm 74 with a concrete extrusion head and a movable robotic arm 75 with a rebar gripper are mounted on the guide beam 73, respectively realizing concrete printing and rebar feeding and installation. A sliding track is set between the movable robotic arm 74 with the concrete extrusion head and the movable robotic arm 75 with the rebar gripper and the guide beam 73, which can move upward on the longitudinal bridge, driven by a motor. The movable robotic arm 74 with the concrete extrusion head and the movable robotic arm 75 with the rebar gripper move laterally on the guide beam 73 via the roller 71, and move vertically via the vertical rod 72.

[0063] In summary, the printing process using this construction device is as follows: Figures 6 to 8 As shown:

[0064] S1. The frame system 5 is fixed in position. Pier 1 is printed. The mobile robotic arm 74 with a concrete extrusion head prints pier unit 11 in layers. Pier unit 11 is printed by 10 3D printed concrete single layers with a thickness of 1cm. After each layer of pier unit 11 is printed, the mobile robotic arm 75 with a steel bar gripper grabs the longitudinal and transverse steel bars and embeds them on the top of pier unit 11 to toughen it. After printing five layers of pier unit 11, the mobile robotic arm 75 with a steel bar gripper grabs the vertical steel bars and inserts them into the interior of the five layers of pier unit 11 to enhance the bending resistance of pier 1.

[0065] S2. The moving positioning beam 61 fixes the position of the stepped suspended formwork, and the lifting rod 62 fixes the height of the stepped suspended formwork. The height of the four lifting rods 62 is adjusted to ensure that the stepped suspended formwork is horizontal.

[0066] S3. The mobile robotic arm 75 with a steel bar gripper grabs the connected steel mesh and places it on the already installed pier 1 and stepped formwork. The mobile robotic arm 74 with a concrete extrusion head moves longitudinally on the guide beam 73 and laterally on the frame beam 52 to print concrete for the supporting beam 21. When the height is not sufficient, the guide beam 73 slides upward along the vertical bar 72 to change the operating height.

[0067] S4. The three-layer support beam unit 21 is a section. After each section is printed, the stepped formwork moves 30cm to each side along the longitudinal direction of the bridge. At the same time, the height of the stepped formwork is raised by 30cm to print the next section of concrete.

[0068] After printing S5 and variable cross-section beam 2, replace the flat plate formwork and print the concrete of bridge deck 3, thus completing the printing of the entire bridge.

[0069] In another optional embodiment of the present invention, bridge deck structures such as bridge deck railings can continue to be printed.

[0070] In another alternative embodiment of the invention, the number of piers 1 and variable cross-section beams 2 can be increased.

[0071] In another optional embodiment of the present invention, the cross-section of the pier 1 can be circular.

[0072] In another optional embodiment of the present invention, vertical reinforcing bars can be inserted into the layered construction variable cross-section beam 2 to enhance the shear resistance of the cross-section and improve the interlayer shear resistance.

[0073] In another optional embodiment of the present invention, the longitudinal length of the hanging mold 63 may not be uniform, that is, it may vary within a safe range, so that the lower edge of the printed bridge is an arc.

[0074] In another optional embodiment of the present invention, the longitudinal reinforcing bars and the transverse reinforcing bars can be fixed by welding, and the welding method can be a welding robotic arm, that is, adding a welding robotic arm.

[0075] The reinforced concrete bridge and suspended printing construction device suitable for 3D printing proposed in this application have the following advantages:

[0076] (1) The structure is novel. It is no longer a common arch bridge or prestressed beam bridge. It does not require printing the cross section and then flipping it. Instead, it is directly 3D printed.

[0077] (2) The structure is novel. It is no longer a masonry structure without steel reinforcement, nor a prestressed structure, but a composite additive manufacturing of steel reinforcement and concrete directly 3D printed, and does not require flipping during construction.

[0078] (3) It can be printed on-site in mid-air, and 3D printed bridges can be printed in mid-air with fewer supports.

[0079] The present invention has been described above with reference to the accompanying drawings. Obviously, the specific implementation of the present invention is not limited to the above-described manner. Any improvements made using the inventive concept and technical solution of the present invention, or direct application to other situations without modification, are all within the protection scope of the present invention.

Claims

1. A suspended, printed reinforced concrete bridge, characterized in that, It includes two piers (1) set along the length of the bridge. Each pier (1) includes several layers of pier units (11) connected from top to bottom. Each layer of pier unit (11) is composed of several 3D printed concrete single layers. The top of each layer of pier unit (11) is embedded with longitudinal and transverse steel bars. Vertical steel bars are inserted inside the pier (1). The bridge pier (1) is provided with a variable cross-section beam (2) at the top. The variable cross-section beam (2) includes several layers of support beam units (21) arranged from top to bottom. The length of the several layers of support beam units (21) from bottom to top extends to both sides. Each layer of support beam unit (21) is composed of several 3D printed concrete single layers. The top of each layer of support beam unit (21) is covered with a steel mesh. The steel mesh is welded and fixed by the transverse steel bars and longitudinal steel bars of the support beam. The bridge deck (3) is supported on the top of the two variable cross-section beams (2). The bridge deck (3) is composed of several 3D printed concrete single layers and has several longitudinal steel bars arranged along the length of the bridge.

2. A suspended printed reinforced concrete bridge according to claim 1, characterized in that, Vertical reinforcing bars are inserted inside the variable cross-section beam (2).

3. A suspended printed reinforced concrete bridge according to claim 2, characterized in that, The length of the pier (1) is 1m, the width is 7m and the height is 2m; the height of the pier unit (11) is 10cm and the pier (1) is composed of 20 pier units (11); the thickness of the 3D printed concrete single layer is 1cm and the pier unit (11) is composed of 10 3D printed concrete single layers.

4. A suspended printed reinforced concrete bridge according to claim 3, characterized in that, The width of the variable cross-section beam (2) is 7m and the height is 3m; the height of the supporting beam unit (21) is 10cm. The variable cross-section beam (2) consists of 30 layers of supporting beam units (21). The length of the uppermost supporting beam unit (21) is 6m and the length of the lowermost supporting beam unit (21) is 20cm. The suspended length of each upper layer of supporting beam unit (21) is 20cm longer than that of the lower layer of supporting beam unit (21), and 10cm longer on each side.

5. A construction device for a suspended printed reinforced concrete bridge as described in claim 4, characterized in that, It includes a track system (4), a frame system (5), a template system (6), and a printing system (7); The track system (4) includes two parallel tracks (41), which are laid out on both sides of the bridge length direction; The frame system (5) is a support frame welded together from two frame longitudinal beams (51) and two frame transverse beams (52). Four frame columns (53) are provided at the four corners of the bottom of the support frame. The bottom of the frame columns (53) is equipped with moving wheels (54), which are rolled on the track (41). The template system (6) includes four positioning beams (61) installed between two frame longitudinal beams (51). The bottom of the positioning beams (61) is rolled on the frame longitudinal beams (51) by drive wheels. The drive wheels are driven by a motor. Each positioning beam (61) is provided with two hanging rods (62). The hanging rods (62) are connected to a winch. A hanging formwork (63) is hung between the four hanging rods (62) of every two positioning beams (61). The hanging formwork (63) includes stepped hanging formwork and flat hanging formwork. The stepped hanging formwork includes three layers of templates and the three layers of templates are set outward from bottom to top. The width of each layer of template is consistent with the width of the support beam unit (21), and the height of each layer of template is consistent with the height of the support beam unit (21). The printing system (7) includes rollers (71) mounted on the frame beam (52). The rollers (71) are driven by a motor. The rollers (71) are connected to vertical rods (72). A guide beam (73) that moves up and down is installed between the two vertical rods (72) via a motor, gears and chains. A movable robotic arm (74) with a concrete extrusion head and a movable robotic arm (75) with a rebar gripper are mounted on the guide beam (73). Both the movable robotic arm (74) with a concrete extrusion head and the movable robotic arm (75) with a rebar gripper are driven by a motor to move the rotating wheels.

6. The construction device for suspended printing of reinforced concrete bridges according to claim 5, characterized in that, The width of each layer of the hanging formwork (63) is 7m, the height is 10cm, and the length is 20cm.

7. A printing method for a construction device for suspended printing of reinforced concrete bridges as described in claim 6, characterized in that, The specific steps are as follows: S1. The frame system (5) is fixed in position and the bridge pier (1) is printed. The mobile robotic arm (74) with concrete extrusion head prints the bridge pier unit (11) in layers. The bridge pier unit (11) is printed by 10 1cm thick 3D printed concrete single layers. After each layer of bridge pier unit (11) is printed, the mobile robotic arm (75) with steel bar gripper grabs the longitudinal and transverse steel bars and embeds them on the top of the bridge pier unit (11) for toughening. After printing five layers of bridge pier unit (11), the mobile robotic arm (75) with steel bar gripper grabs the vertical steel bars and inserts them into the five layers of bridge pier unit (11) to enhance the bending resistance of the bridge pier (1). S2. The moving positioning beam (61) fixes the position of the stepped suspended formwork, and the lifting rod (62) fixes the height of the stepped suspended formwork. The height of the four lifting rods (62) is adjusted to ensure the level of the stepped suspended formwork. S3. The mobile robotic arm (75) with a steel bar gripper grabs the connected steel mesh and places it on the installed pier (1) and stepped formwork. The mobile robotic arm (74) with a concrete extrusion head moves longitudinally on the guide beam (73) and laterally on the frame beam (52) to print the concrete of the supporting beam unit (21). When the height is not sufficient, the guide beam (73) slides upward along the vertical bar (72) to change the operating height. S4. The three-layer support beam (21) is a single section. After each section is printed, the stepped formwork moves 30cm to each side along the longitudinal direction of the bridge. At the same time, the height of the stepped formwork is raised 30cm to print the next section of concrete. After printing the variable cross-section beam (2), replace the flat plate hanging mold and print the concrete of the bridge deck (3), thus completing the printing of the entire bridge.

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