A 3D-printed concrete composite beam

Abstract

This invention discloses a 3D-printed concrete composite beam, belonging to the field of 3D printing technology. It includes: a plurality of 3D-printed concrete units, each printed from 3D concrete material, arranged longitudinally at intervals, with a keyway formed transversely on the tensile side of each unit; a connector located at the end of each 3D-printed concrete unit for fixing adjacent units together; a shear key that engages with the keyway; and a tensile connecting plate located on the tensile side of each 3D-printed concrete unit, with the shear key fixedly connected to it. Compared to traditional 3D-printed concrete, this composite beam can improve the strength of the component, enabling it to meet load-bearing performance requirements.

Description

Technical Field

[0001] This invention belongs to the field of 3D printing technology, and specifically relates to a 3D printed concrete composite beam. Background Technology

[0002] 3D-printed concrete technology is a new type of construction technology with a high degree of digitalization, mechanization, and intelligence. Compared with traditional construction methods, it has advantages such as formwork-free construction, labor saving, and high construction efficiency. In recent years, the application of 3D-printed concrete technology in the construction field has gradually developed and has also attracted widespread attention from scholars at home and abroad. With the continuous advancement of social modernization, traditional civil engineering construction methods will face problems such as serious environmental pollution, insufficient effective labor force, complex sites, and shortage of construction materials. Therefore, applying 3D printing technology to transportation infrastructure construction can promote the transformation and upgrading of the transportation industry, achieving rapid and efficient construction and more aesthetically pleasing structural forms. However, 3D printing construction technology still faces a series of challenges worldwide. At present, 3D printing is mostly used in landscape and non-load-bearing maintenance structures, and there is relatively little research on its application in structural engineering. Currently proposed reinforcement methods for 3D-printed concrete components, such as synchronous printing reinforcement, pre-reserved duct reinforcement, steel mesh reinforcement, and steel wire reinforcement, cannot smoothly install vertical steel bars as smoothly as traditional reinforced concrete structures due to equipment interference problems. Printed structures lack effective reinforcement methods and cannot meet structural performance requirements. Summary of the Invention

[0003] In view of this, the purpose of the present invention is to provide a 3D printed concrete composite beam that, compared with traditional 3D printed concrete, can improve the strength of the component and enable it to meet the load-bearing performance requirements.

[0004] To achieve the above objectives, the present invention provides the following technical solution:

[0005] This invention discloses a 3D-printed concrete composite beam, comprising:

[0006] A plurality of 3D printed concrete units, wherein the 3D printed concrete units are printed from 3D concrete material, and the plurality of 3D printed concrete units are arranged in sequence at intervals along the longitudinal direction, and a keyway is provided on the tensile side of the 3D printed concrete unit along its transverse direction.

[0007] A connector, located at the end of a 3D printed concrete unit, is used to fix two adjacent 3D printed concrete units together.

[0008] A shear key, which mates with a keyway;

[0009] A tensile connecting plate is located on the tensile side of the 3D printed concrete unit, and the shear key is fixedly connected to the tensile connecting plate.

[0010] Furthermore, the connector includes adhesive, which is used to bond adjacent 3D printed concrete units together.

[0011] Furthermore, the 3D printed concrete unit has through holes extending through both ends of it, and energy-dissipating steel bars are inserted into the through holes. There is a certain gap between the energy-dissipating steel bars and the inner wall of the through holes. The energy-dissipating steel bars are located at the gap between two adjacent 3D printed concrete units and are bonded together by the adhesive.

[0012] Furthermore, several elastic steel bars are tightly arranged around the energy-dissipating steel bar, and the outer side of the elastic steel bars abuts against both the energy-dissipating steel bar and the inner wall of the through hole. A positioning piece for longitudinal positioning of the elastic steel bar is provided in the through hole.

[0013] Furthermore, a pressure plate is also sleeved on the outer side of the energy-consuming steel bar, and the pressure plate is in frictional engagement with the inner wall of the through hole. The pressure plate is used to press the elastic steel bar axially against the positioning plate.

[0014] Furthermore, the tensile connecting plate is made of glued laminated timber.

[0015] Furthermore, the 3D printed concrete unit includes a concrete base plate, concrete side plates formed on both sides of the base plate, a first cylinder and a second cylinder formed between the two concrete side plates. The base plate has the keyway. A plurality of first cylinders are located on the side closer to the base plate and are arranged in parallel along the transverse direction. A plurality of second cylinders are located on the side away from the base plate and are arranged in parallel along the transverse direction.

[0016] The beneficial effects of this invention are as follows:

[0017] This invention discloses a 3D-printed concrete composite beam. The bending member adopts a structural form combining 3D-printed concrete and glued laminated timber. The glued laminated timber is placed in the tensile zone of the member and together with the 3D-printed concrete unit forms the bending member. Compared with traditional 3D-printed concrete, the combination with glued laminated timber can improve the strength of the member and make it meet the load-bearing (structural) performance requirements. The direct connection through transverse shear keys can improve the installation efficiency of the concrete composite beam and facilitate its use during on-site construction.

[0018] Other advantages, objectives, and features of the invention will be set forth in the following description and will be apparent to those skilled in the art in some respects, or may be learned by practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0019] To make the objectives, technical solutions, and beneficial effects of this invention clearer, the following figures are provided for illustration:

[0020] Figure 1 This is a schematic diagram of the composite beam in Example 1;

[0021] Figure 2 This is a schematic diagram of the arrangement of energy-consuming steel bars in Example 1;

[0022] Figure 3 This is a schematic diagram showing the position of the positioning piece in Example 1;

[0023] Figure 4 This is a schematic diagram of the arrangement of energy-consuming steel bars in Example 1;

[0024] Figure 5 This is a schematic diagram of the connection method for composite beams;

[0025] Figure 6 This is a schematic diagram of the shear key arrangement in Example 2;

[0026] Figure 7 Experimental diagram of the glued laminated timber-UHPC interface;

[0027] Figure 8 Finite element simulation diagram of the glued laminated timber-UHPC interface;

[0028] Figure 9 Force-displacement experimental curves for the glued laminated timber-UHPC interface;

[0029] Figure 10 Experimental diagram of 3D printed concrete-UHPC interface;

[0030] Figure 11 Experimental stress bar chart for 3D printed concrete-UHPC interface.

[0031] The following are labeled in the attached diagram: 3D printed concrete unit 1, concrete base plate 1a, concrete side plate 1b, first cylinder 1c, second cylinder 1d, keyway 2, connector 3, shear key 4, tensile connecting plate 5, through hole 6, energy dissipation steel bar 7, elastic steel bar 8, positioning plate 9, pressure plate 10. Detailed Implementation

[0032] Example 1, as Figures 1-4As shown, this invention discloses a 3D-printed concrete composite beam, comprising: a plurality of 3D-printed concrete units 1, connectors 3, shear keys 4, and tensile connecting plates 5. The 3D-printed concrete units 1 are printed from 3D concrete material. The plurality of 3D-printed concrete units 1 are arranged longitudinally at intervals, where longitudinal refers to the length direction of the concrete component. A keyway 2 is provided transversely on the tensile side of each 3D-printed concrete unit 1. The shear keys 4 mate with the keyway 2, and the direction of the shear keys 4 is perpendicular to the extension direction of the 3D-printed concrete unit 1. The shear keys 4 are fixedly connected to the tensile connecting plates 5 by self-tapping screws. The tensile side is located at the bottom of the concrete. The connectors 3 are located at the ends of the 3D-printed concrete units 1 and are used to fix two adjacent 3D-printed concrete units 1 together. The tensile connecting plates 5 are located on the tensile side of the 3D-printed concrete units 1, and the shear keys 4 are fixedly connected to the tensile connecting plates 5. The tensile connecting plates 5 enhance the performance of the concrete in the tension zone. The tensile connecting plate 5 is made of glued laminated timber, whose high strength makes it resistant to deformation and bending, and it also has good tensile strength in its cross-section. Grooves need to be cut into the glued laminated timber and 3D-printed concrete, and then UHPC is poured into the holes to improve the connection strength. Using the composite beam of this invention, the strength of the 3D-printed concrete can be increased without considering reinforcement, making it suitable for application in building engineering. Figure 5 This diagram illustrates the connection methods of self-tapping screws under six different combinations of shear grooves and glued laminated timber.

[0033] In this embodiment, the connector 3 includes adhesive. Adhesive is used to bond two adjacent 3D printed concrete units 1 together, which makes it easy to connect the two adjacent 3D printed concrete units 1. Of course, the connection between the two can also be made by physical connection methods such as riveting, but this method is easy to damage the surface of the 3D printed concrete unit 1.

[0034] In this embodiment, the 3D-printed concrete unit 1 has through holes 6 extending through both ends of it. Energy-dissipating reinforcing bars 7 are inserted into the through holes 6. The inner diameter of the through holes 6 is larger than the outer diameter of the energy-dissipating reinforcing bars 7, thus creating a certain gap between the energy-dissipating reinforcing bars 7 and the inner wall of the through holes 6. The energy-dissipating reinforcing bars 7 are bonded to adjacent 3D-printed concrete units 1 at the gap position using adhesive. By setting the energy-dissipating reinforcing bars 7, the tensile performance of the beam can be increased. When two adjacent 3D-printed concrete units 1 are under tension, the energy-dissipating reinforcing bars 7 can be pulled simultaneously, causing them to deform and thus dissipating energy. Furthermore, even if two adjacent 3D-printed concrete units 1 are subjected to shear force, the force can still be applied to the energy-dissipating reinforcing bars 7, which dissipate energy after deformation.

[0035] In this embodiment, several elastic steel bars 8 are tightly arranged around the energy-dissipating steel bar 7. The elastic steel bars 8 are hollow elastic steel cylinders made of elastic steel, which can dissipate energy through compression. The outer side of the elastic steel bars 8 also abuts against both the energy-dissipating steel bar 7 and the inner wall of the through hole 6. A positioning piece 9 for longitudinal positioning of the elastic steel bars 8 is provided inside the through hole 6. A pressure piece 10 is also sleeved on the outer side of the energy-dissipating steel bar 7. The pressure piece 10 frictionally engages with the inner wall of the through hole 6, and is used to press the elastic steel bars 8 axially against the positioning piece 9, facilitating the positioning and installation of the elastic steel bars 8. The tensile connecting plate 5 is made of glued laminated timber.

[0036] In this embodiment, the 3D printed concrete unit 1 includes a concrete base plate 1a, concrete side plates 1b formed on both sides of the base plate, a first cylinder 1c and a second cylinder 1d formed between the two concrete side plates 1b. The base plate has a keyway 2. A plurality of first cylinders 1c are located on the side closer to the base plate and are arranged in parallel along the transverse direction. A plurality of second cylinders 1d are located on the side farther from the base plate and are arranged in parallel along the transverse direction. By adopting this 3D printed concrete unit 1 structure, the amount of 3D printed concrete unit 1 used is reduced while ensuring the strength of the concrete, making it more economical to use.

[0037] Example 2 differs from Example 1 in that the direction of the shear key 4 is parallel to the extension direction of the 3D printed concrete unit 1. The shear key 4 is along the longitudinal direction of the tensile connecting plate 5, and corresponding keyways 2 are provided on both the tensile connecting plate 5 and the concrete base plate 1a.

[0038] This 3D-printed concrete composite beam connects the tensile members (glulam / steel beams) and the compressive members (3D-printed concrete) by filling the tensile members with UHPC. To clarify the reliability and feasibility of this connection method, we conducted experiments on the mechanical properties of the connectors. In this composite beam, there are two main interfaces for shear connection: the UHPC-glulam connection interface and the 3D-printed concrete-UHPC connection interface. Therefore, the performance study of the connectors was first conducted based on these two interface connections.

[0039] like Figures 7-9 As shown, experimental and finite element simulations of the UHPC-glulam joint interface performance investigated the shear resistance, stress mechanism, and failure mode of different connection types (screw only, slotted only, and screw + slotted). The comprehensive experimental results show that all three connection types have significant load-bearing capacity, with the tenon-screw type exhibiting the highest stiffness and load-bearing capacity.

[0040] like Figure 10 and 11The image shows an experiment demonstrating the interface formation between 3D-printed concrete (3DPC) and UHPC. Since 3D-printed concrete exhibits different interface forms compared to traditional concrete, such as inter-strip and inter-layer interfaces, this experiment primarily explores the connection between 3D-printed concrete and UHPC by controlling various interface parameters (e.g., inter-layer, inter-strip, and inter-layer / strip interfaces), considering whether the outer surface is cut, and different loading directions (i.e., loading parallel to and perpendicular to the inter-layer / strip interface).

[0041] Shear test results of the interface bonding between 3D-printed concrete and UHPC show that the 3DPC interface with a normal outer surface exhibits excellent ductility and high load-bearing capacity, while the interlayer-to-strip interface bonding performance is superior to the interlayer interface and even superior to the strip interface. Therefore, in practical design, the interlayer-to-strip interface bonding method with a normal outer surface will be recommended. In other words, the results analysis demonstrates that 3D-printed concrete-UHPC exhibits good bonding performance.

[0042] In summary, through experiments and finite element simulation analysis, the novel 3D-printed concrete composite beam, which connects 3D-printed concrete and tensile members (glulam) via UHPC, exhibits excellent connection performance. The connectors are rationally designed, have high strength, and can fully utilize their connection characteristics. This novel composite beam demonstrates good feasibility and practicality.

[0043] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made to it in form and detail without departing from the scope defined by the claims of the present invention.

Claims

1. A 3D-printed concrete composite beam, characterized in that, include: A plurality of 3D printed concrete units, wherein the 3D printed concrete units are printed from 3D concrete material, and the plurality of 3D printed concrete units are arranged in sequence at intervals along the longitudinal direction, and a keyway is provided on the tensile side of the 3D printed concrete unit along its transverse direction. A connector, located at the end of a 3D printed concrete unit, is used to fix two adjacent 3D printed concrete units together. A shear key, which mates with a keyway; A tensile connecting plate is located on the tensile side of the 3D printed concrete unit, and the shear key is fixedly connected to the tensile connecting plate; The 3D printed concrete unit has through holes extending through both ends. Energy-dissipating steel bars are inserted into the through holes, with a certain gap between the energy-dissipating steel bars and the inner wall of the through holes. Several elastic steel bars are also tightly arranged around the energy-dissipating steel bars. The outer side of the elastic steel bars abuts against both the energy-dissipating steel bars and the inner wall of the through holes. A positioning piece for longitudinal positioning of the elastic steel bars is provided in the through holes. A pressure piece is also sleeved on the outer side of the energy-dissipating steel bars, and the pressure piece is in frictional engagement with the inner wall of the through holes. The pressure piece is used to press the elastic steel bars axially against the positioning piece. The 3D printed concrete unit includes a concrete base plate, concrete side plates formed on both sides of the base plate, a first cylinder and a second cylinder formed between the two concrete side plates. The base plate has the keyway. A plurality of first cylinders are located on the side closer to the base plate and are arranged in parallel along the transverse direction. A plurality of second cylinders are located on the side away from the base plate and are arranged in parallel along the transverse direction.

2. The 3D-printed concrete composite beam according to claim 1, characterized in that, The connector includes adhesive, which is used to bond two adjacent 3D printed concrete units together.

3. The 3D-printed concrete composite beam according to claim 1, characterized in that, The energy-consuming steel bars are bonded together with adhesive at the interval between two adjacent 3D printed concrete units.

4. The 3D-printed concrete composite beam according to claim 1, characterized in that, The tensile connecting plate is glued laminated wood.

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