An FRP-UHPC concrete composite column and its construction method

Abstract

This invention provides an FRP-UHPC concrete composite column and its construction method, solving the problems of frequent damage at the interface of steel-concrete composite structures and the susceptibility of the outer steel pipe to corrosion and rust, leading to potential safety hazards in the building structure. The invention includes an inner UHPC pipe and an outer UHPC pipe, with the outer UHPC pipe sleeved over the inner UHPC pipe. A first open groove, penetrating vertically and internally, is formed on the wall of the inner UHPC pipe. Cast-in-place concrete is filled between the inner and outer UHPC pipes. An FRP fabric layer covers the outer circumference of the outer UHPC pipe. This invention uses layered UHPC pipes instead of steel pipes as a constraint during concrete pouring, combined with the outer FRP layer, ensuring that the thermal expansion coefficient of the formed beam and column remains consistent, thus avoiding the frequent damage at the interface caused by the different moduli and thermal expansion coefficients of concrete and steel in steel-concrete composite structures.

Description

Technical Field

[0001] This invention relates to the field of building structural engineering, and in particular to an FRP-UHPC concrete composite column and its construction method. Background Technology

[0002] With the continuous development of construction technology, steel-concrete composite structures are now frequently used for beam and column construction in buildings. A steel-concrete composite structure uses precast hollow beams and columns made of prefabricated steel plates on the outside. During construction, after the precast hollow beams and columns are joined together, concrete is poured into them, allowing the beam and column structure to form quickly and accelerating the construction speed.

[0003] However, this type of steel-concrete composite structure also has the following problems: (1) Concrete and steel have different moduli and coefficients of thermal expansion, which leads to inconsistent deformation between concrete and steel pipes, resulting in frequent damage at the interface of the steel-concrete composite structure. Moreover, since these defects are hidden inside the steel pipe, they are difficult to measure and monitor, making it difficult to detect and deal with safety hazards in the building structure in a timely manner; (2) Steel pipes are easily corroded and rusted, especially in corrosive environments (such as chemical plants, offshore platforms, and nuclear power plants), which greatly reduces their service life and makes the building structure prone to safety hazards. Summary of the Invention

[0004] To address the problems in the prior art where damage frequently occurs at the interface of steel-concrete composite structures, and the outer steel pipe is prone to corrosion and rust, leading to potential safety hazards in the building structure, this invention proposes an FRP-UHPC concrete composite column and its construction method.

[0005] The technical solution of the present invention is: an FRP-UHPC concrete composite column, comprising an inner UHPC tube and an outer UHPC tube, wherein the inner diameter of the outer UHPC tube is larger than the outer diameter of the inner UHPC tube, the outer UHPC tube is sleeved on the outside of the inner UHPC tube, and the outer UHPC tube and the inner UHPC tube are concentric circles.

[0006] The inner UHPC tube has a first opening groove that runs vertically through the tube and is open to both the inside and outside.

[0007] The inner layer of UHPC pipe and the space between the outer layer of UHPC pipe and the inner layer of UHPC pipe are filled with cast-in-place concrete;

[0008] The outer circumferential surface of the outer UHPC tube is covered with an FRP cloth layer.

[0009] Preferably, a middle UHPC tube is provided between the inner UHPC tube and the outer UHPC tube, and the middle UHPC tube, the outer UHPC tube, and the inner UHPC tube are all concentric circle structures.

[0010] The inner diameter of the middle layer UHPC tube is larger than the outer diameter of the inner layer UHPC tube, and the outer diameter of the middle layer UHPC tube is smaller than the inner diameter of the outer layer UHPC tube.

[0011] The middle layer UHPC tube has a second opening groove that runs vertically through the tube and is open to both the inside and outside.

[0012] The interior of the inner UHPC pipe, the space between the middle UHPC pipe and the inner UHPC pipe, and the space between the outer UHPC pipe and the middle UHPC pipe are all filled with cast-in-place concrete.

[0013] Preferably, multiple nested intermediate UHPC pipes are provided between the inner and outer UHPC pipes, with the diameter of the nested intermediate UHPC pipes increasing sequentially from the inside to the outside, and gaps for filling with cast-in-place concrete existing between adjacent inner and outer intermediate UHPC pipes.

[0014] Preferably, the gap thickness between the inner UHPC tube and the middle UHPC tube, between adjacent middle UHPC tubes, and between the middle UHPC tube and the outer UHPC tube is 10cm to 15cm.

[0015] Preferably, the middle layer UHPC pipe is embedded with multiple layers of pre-embedded pipes spaced apart vertically, with at least three pre-embedded pipes in each layer. The pre-embedded pipes in each layer are evenly arranged along the circumference of the middle layer UHPC pipe. The pre-embedded pipes have an inner tube through structure and extend radially along the middle layer UHPC pipe.

[0016] The embedded pipe is equipped with a horizontal bracing steel bar, which extends radially along the middle layer UHPC pipe. One end of the horizontal bracing steel bar abuts against the outer wall of the inner layer UHPC pipe, and the other end of the horizontal bracing steel bar abuts against the inner wall of the outer layer UHPC pipe.

[0017] Preferably, the outer wall of the inner UHPC tube is provided with a slot, which is a semi-open groove structure; one end of the cross bracing steel bar is inserted into the slot, and the end of the cross bracing steel bar abuts against the bottom of the slot.

[0018] A construction method for an FRP-UHPC concrete composite column includes the following steps: S1~ Before construction, according to the design drawings, UHPC prefabricates inner layer UHPC pipe, middle layer UHPC pipe, outer layer UHPC pipe and cross bracing steel bars in the factory. During prefabrication, the embedded pipe is pre-installed in the side wall of the middle layer UHPC pipe for the cross bracing steel bars to pass through.

[0019] S2~ During construction, draw the installation positions of the inner layer UHPC pipe, middle layer UHPC pipe and outer layer UHPC pipe at the construction site according to the design drawings;

[0020] S3~ The inner layer UHPC tube and the middle layer UHPC tube are hoisted to their installation positions in sequence, so that the middle layer UHPC tube is sleeved on the outside of the inner layer UHPC tube, and the pre-embedded tubes correspond one by one with the slots;

[0021] S4~ Insert the cross bracing steel bar into the pre-embedded pipe on the middle layer UHPC pipe, and make one end of the cross bracing steel bar abut against the slot on the inner layer UHPC pipe;

[0022] S5~ Hoist the outer UHPC pipe to its installation position, so that the outer UHPC pipe is sleeved on the outside of the end of the cross brace steel bar away from the UHPC pipe;

[0023] S6~ From top to bottom, pour cast-in-place concrete into the inner layer UHPC pipe and vibrate it so that the cast-in-place concrete fills the gaps in the inner layer UHPC pipe, between the middle layer UHPC pipes, between adjacent middle layer UHPC pipes, and between the middle layer UHPC pipe and the outer layer UHPC pipe.

[0024] S7~After the cast-in-place concrete has solidified, an FRP fabric layer is applied to the outer circumferential surface of the outer UHPC pipe.

[0025] Advantages of this invention: In this invention, the thermal expansion coefficient of FRP composite material is similar to that of concrete. When the ambient temperature changes, the FRP material and concrete work in coordination, and no large temperature stress is generated between them. At the same time, the use of UHPC pipe instead of steel pipe as a constraint during concrete pouring ensures that the thermal expansion coefficient of the formed beams and columns remains consistent. This avoids the problem of inconsistent deformation between concrete and steel pipes in steel-concrete composite structures due to their different moduli and thermal expansion coefficients, which often leads to damage at the interface of the steel-concrete composite structure.

[0026] Meanwhile, the layered arrangement of inner and outer UHPC pipes ensures that the finished composite column possesses the excellent properties of UHPC material, such as wear resistance, impact resistance, and corrosion resistance. Furthermore, depending on the application scenario, different types of cast-in-place concrete, such as ordinary concrete (NSC), high-performance concrete (HPC), and ultra-high-performance concrete (UHPC), can be poured between the inner and outer UHPC pipes. This allows the finished composite column to meet application requirements while minimizing costs. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is a schematic diagram of the main structure from a top view in Example 1;

[0029] Figure 2 for Figure 1 A schematic diagram of the multilayer UHPC tube structure in the diagram;

[0030] Figure 3 for Figure 1 A schematic diagram of the inner UHPC tube structure;

[0031] Figure 4 for Figure 1 A schematic diagram of the middle layer UHPC tube in the diagram;

[0032] Figure 5 for Figure 1 A schematic diagram of the outer UHPC tube structure;

[0033] In the diagram, 1 is the inner UHPC pipe, 101 is the first opening groove, 102 is the slot, 2 is the middle UHPC pipe, 201 is the second opening groove, 202 is the embedded pipe, 3 is the outer UHPC pipe, 4 is the FRP layer, 5 is the cross bracing reinforcement, and 6 is the cast-in-place concrete. Detailed Implementation

[0034] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] Example 1: An FRP-UHPC concrete composite column, such as Figure 1 and Figure 2 As shown, it includes an inner UHPC tube 1 and an outer UHPC tube 3. The inner diameter of the outer UHPC tube 3 is larger than the outer diameter of the inner UHPC tube 1, and the outer UHPC tube 3 is sleeved on the outside of the inner UHPC tube 1.

[0036] like Figure 3 As shown, the inner UHPC tube 1 has a first opening groove 101 that runs vertically through the tube and is transparent to both the inside and outside.

[0037] Between the inner UHPC pipe 1 and the outer UHPC pipe 3, there are two nested middle UHPC pipes 2. The diameter of the nested middle UHPC pipes 2 increases from the inside to the outside, and there are gaps between the inner and outer adjacent middle UHPC pipes 2 for the cast-in-place concrete 6 to fill.

[0038] The gap thickness between the inner UHPC tube 1 and the middle UHPC tube 2, between adjacent middle UHPC tubes 2, and between the middle UHPC tube 2 and the outer UHPC tube 3 should be 10cm to 15cm.

[0039] The middle layer UHPC tube 2, the outer layer UHPC tube 3, and the inner layer UHPC tube 1 are all concentric circle structures.

[0040] The innermost middle layer UHPC tube 2 has a larger inner diameter than the outer diameter of the inner layer UHPC tube 1, and the outermost middle layer UHPC tube 2 has a smaller outer diameter than the inner diameter of the outer layer UHPC tube 3.

[0041] like Figure 4 As shown, a second opening groove 201 is provided on the wall of the middle layer UHPC pipe 2, which is open from top to bottom and transparent from inside to outside.

[0042] The inner layer UHPC pipe 1, the middle layer UHPC pipe 2 and the inner layer UHPC pipe 1, and the outer layer UHPC pipe 3 and the middle layer UHPC pipe 2 are all filled with cast-in-place concrete 6. All the cast-in-place concrete 6 are connected together by the first opening groove 101 and the second opening groove 201, and the inner layer UHPC pipe 1, the middle layer UHPC pipe 2 and the outer layer UHPC pipe 3 are connected together.

[0043] To improve the overall bond strength between the inner UHPC pipe 1, the middle UHPC pipe 2, the outer UHPC pipe 3, and the cast-in-place concrete 6, such as Figure 1 , Figure 2 , Figure 3 and Figure 4 As shown, multiple layers of pre-embedded pipes 201 are embedded in the wall of the middle layer UHPC pipe 2 at intervals. There are three pre-embedded pipes 201 in each layer. The pre-embedded pipes 201 in each layer are evenly arranged along the circumference of the middle layer UHPC pipe 2. The pre-embedded pipes 201 have an inner tube through structure and extend radially along the middle layer UHPC pipe 2.

[0044] The inner UHPC tube 1 has a slot 102 on its outer side wall. The slot 102 is a semi-open groove structure.

[0045] A cross bracing steel bar 5 is inserted inside the pre-embedded pipe 201. The cross bracing steel bar 5 extends radially along the middle layer UHPC pipe 2. One end of the cross bracing steel bar 5 is inserted into the slot 102, and the end of the cross bracing steel bar 5 abuts against the bottom of the slot 102. The other end of the cross bracing steel bar 5 abuts against the inner wall of the outer layer UHPC pipe 3.

[0046] like Figure 1 and Figure 2 As shown, in this embodiment, an FRP cloth layer 4 is wrapped and attached to the outer circumferential surface of the outer UHPC pipe 3 to improve the structural strength and corrosion resistance of the formed beam and column.

[0047] A construction method for an FRP-UHPC concrete composite column includes the following steps: S1~ Before construction, according to the design drawings, UHPC prefabricates an inner layer UHPC pipe 1, a middle layer UHPC pipe 2, an outer layer UHPC pipe 3, and cross bracing steel bars 5 in the factory. During prefabrication, a pre-embedded pipe 201 is pre-installed in the side wall of the middle layer UHPC pipe 2 for the cross bracing steel bars 5 to pass through.

[0048] S2~ During construction, draw the installation positions of the inner UHPC pipe 1, the middle UHPC pipe 2, and the outer UHPC pipe 3 at the construction site according to the design drawings.

[0049] S3~ The inner layer UHPC tube 1 and the middle layer UHPC tube 2 are hoisted to their respective installation positions in sequence, so that the middle layer UHPC tube 2 is sleeved on the outside of the inner layer UHPC tube 1, and the pre-embedded tube 201 corresponds one-to-one with the slot 102.

[0050] S4~ Insert the cross bracing steel bar 5 into the pre-embedded pipe 201 on the middle layer UHPC pipe 2, and make one end of the cross bracing steel bar 5 abut against the slot 102 on the inner layer UHPC pipe 1.

[0051] S5~ Hoist the outer UHPC pipe 3 to its installation position, so that the outer UHPC pipe 3 is sleeved on the outside of the cross brace 5 away from the end of the UHPC pipe 1.

[0052] S6~ From top to bottom, pour cast-in-place concrete 6 into the inner UHPC pipe 1 and vibrate it so that the cast-in-place concrete 6 fills the gaps in the inner UHPC pipe 1, between the middle UHPC pipe 2 and the inner UHPC pipe 1, between adjacent middle UHPC pipes 2, and between the middle UHPC pipe 2 and the outer UHPC pipe 3.

[0053] S7~After the cast-in-place concrete 6 has solidified, an FRP cloth layer 4 is applied to the outer circumferential surface of the outer UHPC pipe 3.

[0054] In this invention, the thermal expansion coefficient of FRP composite material is similar to that of concrete. When the ambient temperature changes, the FRP material and concrete work in harmony, and no large temperature stress is generated between them. At the same time, the use of UHPC pipe instead of steel pipe as a constraint during concrete pouring ensures that the thermal expansion coefficient of the formed beams and columns remains consistent. This avoids the problem of inconsistent deformation between concrete and steel pipes in steel-concrete composite structures due to their different moduli and thermal expansion coefficients, which often leads to damage at the interface of the steel-concrete composite structure.

[0055] Meanwhile, the layered arrangement of inner UHPC pipe 1, middle UHPC pipe 2, and outer UHPC pipe 3 ensures that the formed composite column possesses the excellent properties of UHPC material, such as wear resistance, impact resistance, and corrosion resistance. Furthermore, depending on the application scenario, different types of cast-in-place concrete 6, such as ordinary concrete (NSC), high-performance concrete (HPC), and ultra-high-performance concrete (UHPC), can be poured between the inner UHPC pipe 1, middle UHPC pipe 2, and outer UHPC pipe 3. This allows the formed composite column to meet application requirements while minimizing costs.

[0056] Compared to structures that only have one layer of UHPC pipe on the outside of the composite column, this invention uses an inner layer of UHPC pipe 1, a middle layer of UHPC pipe 2, and an outer layer of UHPC pipe 3 arranged in layers. A first opening groove 101 is formed on the wall of the inner layer UHPC pipe 1, and a second opening groove 201 is formed on the wall of the middle layer UHPC pipe 2. This results in better connection strength between the cast-in-place concrete 6 and the UHPC pipes, and reduces the likelihood of detachment at the interlayer interface. Combined with the horizontal bracing steel bars 5 arranged in the upper and lower layers, the structural strength of the composite column formed by the combination of the inner layer UHPC pipe 1, the middle layer UHPC pipe 2, and the cast-in-place concrete 6 is even more superior.

[0057] Moreover, during construction, the cross bracing steel bars 5 can "support" the gaps between the middle layer UHPC pipe 2 and the inner layer UHPC pipe 1, between adjacent middle layer UHPC pipes 2, and between the middle layer UHPC pipe 2 and the outer layer UHPC pipe 3. This prevents the inner layer UHPC pipe 1, the middle layer UHPC pipe 2, and the outer layer UHPC pipe 3 from becoming eccentric under the impact of concrete during pouring. This ensures that the thickness of the cast-in-place concrete 6 between each layer is consistent after the composite column is formed, resulting in a better forming effect for the composite column.

[0058] Example 2: An FRP-UHPC concrete composite column. The difference between this example and Example 1 is that three nested intermediate UHPC pipes 2 are provided between the inner UHPC pipe 1 and the outer UHPC pipe 3. The other structures are the same as in Example 1.

[0059] Example 3: An FRP-UHPC concrete composite column. The difference between this example and Example 1 is that a middle UHPC pipe 2 is provided between the inner UHPC pipe 1 and the outer UHPC pipe 3. The other structures are the same as in Example 1.

[0060] Example 4: An FRP-UHPC concrete composite column. The difference between this example and Example 1 is that multiple layers of pre-embedded pipes 201 are embedded in the wall of the middle layer UHPC pipe 2, arranged at intervals between each other, with at least five pre-embedded pipes 201 in each layer. The other structures are the same as in Example 1.

[0061] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims and not by the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. An FRP-UHPC concrete composite column, characterized in that: It includes an inner UHPC tube (1) and an outer UHPC tube (3). The inner diameter of the outer UHPC tube (3) is larger than the outer diameter of the inner UHPC tube (1). The outer UHPC tube (3) is sleeved on the outside of the inner UHPC tube (1). The outer UHPC tube (3) and the inner UHPC tube (1) are concentric circles. The inner UHPC tube (1) has a first opening groove (101) that is vertically connected and transparent to both the inside and outside. The inner layer UHPC pipe (1) and the space between the inner layer UHPC pipe (3) and the inner layer UHPC pipe (1) are filled with cast-in-place concrete (6). An FRP cloth layer (4) is provided on the outer circumferential surface of the outer UHPC tube (3); A middle UHPC tube (2) is provided between the inner UHPC tube (1) and the outer UHPC tube (3). The middle UHPC tube (2), the outer UHPC tube (3), and the inner UHPC tube (1) are all concentric circle structures. The inner diameter of the middle layer UHPC tube (2) is larger than the outer diameter of the inner layer UHPC tube (1), and the outer diameter of the middle layer UHPC tube (2) is smaller than the inner diameter of the outer layer UHPC tube (3). The middle layer UHPC pipe (2) has a second opening groove (201) that is vertically connected and internally and externally permeable. The interior of the inner UHPC pipe (1), the space between the middle UHPC pipe (2) and the inner UHPC pipe (1), and the space between the outer UHPC pipe (3) and the middle UHPC pipe (2) are all filled with cast-in-place concrete (6). The middle layer UHPC pipe (2) is embedded with multiple layers of pre-embedded pipes (202) spaced apart vertically. Each layer has at least three pre-embedded pipes (202). The pre-embedded pipes (202) in each layer are evenly arranged along the circumference of the middle layer UHPC pipe (2). The pre-embedded pipes (202) have an inner tube through structure and extend radially along the middle layer UHPC pipe (2). The embedded pipe (202) is provided with a cross bracing steel bar (5). The cross bracing steel bar (5) extends radially along the middle layer UHPC pipe (2). One end of the cross bracing steel bar (5) abuts against the outer side wall of the inner layer UHPC pipe (1), and the other end of the cross bracing steel bar (5) abuts against the inner side wall of the outer layer UHPC pipe (3). The first opening groove (101) and the second opening groove (201) are staggered in the circumferential direction of the concrete composite column.

2. The FRP-UHPC concrete composite column as described in claim 1, characterized in that: Multiple nested middle-layer UHPC pipes (2) are provided between the inner layer UHPC pipe (1) and the outer layer UHPC pipe (3). The diameter of the nested middle-layer UHPC pipes (2) increases from the inside to the outside, and there are gaps between the inner and outer adjacent middle-layer UHPC pipes (2) for filling with cast-in-place concrete (6).

3. The FRP-UHPC concrete composite column as described in claim 2, characterized in that: The gap thickness between the inner UHPC tube (1) and the middle UHPC tube (2), between adjacent middle UHPC tubes (2), and between the middle UHPC tube (2) and the outer UHPC tube (3) is 10cm~15cm.

4. The FRP-UHPC concrete composite column as described in claim 1, characterized in that: The inner UHPC tube (1) has a slot (102) on its outer side wall. The slot (102) is a semi-open groove structure. One end of the cross bracing steel bar (5) is inserted into the slot (102), and the end of the cross bracing steel bar (5) abuts against the bottom of the slot (102).

5. The construction method of an FRP-UHPC concrete composite column as described in claim 4, characterized in that, The following steps are involved: S1. Before construction, according to the design drawings, the inner layer UHPC pipe (1), the middle layer UHPC pipe (2), the outer layer UHPC pipe (3) and the cross bracing steel bars (5) are prefabricated in the factory. During the prefabrication, the embedded pipe (201) is left in the side wall of the middle layer UHPC pipe (2) so that the cross bracing steel bars (5) can pass through. S2. During construction, draw the installation positions of the inner UHPC pipe (1), middle UHPC pipe (2), and outer UHPC pipe (3) at the construction site according to the design drawings. S3. Hoist the inner UHPC tube (1) and the middle UHPC tube (2) to their installation positions one after another, so that the middle UHPC tube (2) is sleeved on the outside of the inner UHPC tube (1), and the pre-embedded tube (201) corresponds to the slot (102) one by one; S4. Insert the cross bracing steel bar (5) into the pre-embedded pipe (201) on the middle layer UHPC pipe (2), and make one end of the cross bracing steel bar (5) abut against the slot (102) on the inner layer UHPC pipe (1); S5. Hoist the outer UHPC pipe (3) to its installation position so that the outer UHPC pipe (3) is sleeved on the outside of the end of the cross bracing steel bar (5) away from the inner UHPC pipe (1); S6. From top to bottom, pour cast-in-place concrete (6) into the inner UHPC pipe (1) and vibrate it so that the cast-in-place concrete (6) fills the gaps between the inner UHPC pipe (1), the middle UHPC pipe (2) and the inner UHPC pipe (1), the adjacent middle UHPC pipe (2), and the middle UHPC pipe (2) and the outer UHPC pipe (3); S7. After the cast-in-place concrete (6) has solidified, an FRP cloth layer (4) is applied to the outer circumference of the outer UHPC pipe (3).

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