Concrete column with plastic hinge area coated with SMAF-ECC shell and construction method of concrete column
By using SMAF-ECC shell cladding technology on the plastic hinge area of the concrete column, and using high-performance SMAF-ECC materials, the problems of insufficient seismic performance and poor self-restoration of the concrete column are solved, and the effect of significantly improving seismic performance and self-restoration of the damage is achieved.
Patent Information
- Application Number
- CN202510029704.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-08
- Publication Date
- 2025-04-25
AI Technical Summary
The existing concrete columns have insufficient seismic resistance under the action of earthquakes and have poor self-restoration of damage, making it difficult to effectively exert the material properties of shape memory alloy fibers (SMAFs) and engineered cement-based composite materials (ECCs).
The plastic hinge area of the concrete column is covered with an SMAF-ECC shell. By adding the superelastic shape memory alloy fiber SMAF with a volume ratio between 0.5% and 1% to the ECC, a high-performance composite material SMAF-ECC is formed to cover the plastic hinge area of the concrete column.
It significantly improves the seismic performance and damage self-restoration ability of concrete columns, provides better damage tolerance, higher shear bearing capacity and energy consumption, reduces post-seismic repair costs, and optimizes the formation mechanism of plastic hinges.
Smart Images
Figure CN119877780A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of reinforced concrete component reinforcement, and in particular to a concrete column with a plastic hinge zone covered by a SMAF-ECC shell and a construction method thereof. Background Art
[0002] In the seismic design of engineering structures, ductility can be understood as the ability of a structure or component to produce nonlinear deformation without a significant reduction in bearing capacity. The damage concentration area of a ductile component is often called a plastic hinge. Through the rotational deformation of the plastic hinge, the ductile component can effectively dissipate seismic energy. Therefore, the formation and development of the plastic hinge is a key factor in determining the seismic performance of the structure. Based on the principle of capacity protection design, the location of the plastic hinge in the engineering structure can be clearly identified, so that the ductility of the component can be directly linked to the overall ductility of the engineering structure. At the same time, the ductile components at the preset plastic hinge position can be specially designed, and materials with high ductility, high energy dissipation and self-recovery properties can be selected to make the failure mode of the structure under earthquake action predictable and recoverable.
[0003] At present, shifting the improvement of concrete column design criteria towards the use of new materials with high ductility, high energy absorption and self-recovery properties has become one of the important ways to improve the seismic performance of plastic hinge zones. This method can fundamentally change the mechanical behavior and failure mode of concrete columns under earthquakes, thereby comprehensively improving the seismic performance and damage self-recovery performance of concrete columns.
[0004] Shape memory alloy fiber (SMAF) reinforced engineering cement-based composite (ECC) is a new high-performance composite material SMAF-ECC obtained by combining high-ductility ECC with superelastic SMAF. This new composite material can effectively exert the material properties of ECC and SMAF, and has the high ductility, high energy dissipation and multi-crack cracking characteristics of ECC; it can also use the superelasticity of SMAF to effectively restore the fine cracks generated in the ECC matrix and reduce residual deformation; and SMAF is evenly dispersed in the matrix material, which can constrain and repair the fine cracks of the matrix in different directions and different parts, and is very suitable for ECC materials with large-scale cracking. Using SMAF-ECC to cover the plastic hinge area of concrete columns can provide better damage tolerance, higher shear bearing capacity and energy dissipation capacity; it can also replace part of the stirrups to play a lateral constraint role, effectively enhancing the rotation deformation capacity of the plastic hinge area at the column end. Summary of the invention
[0005] One of the purposes of the present invention is to provide a concrete column with a plastic hinge area covered by a SMAF-ECC shell, which has high tensile strength, good ductility, strong energy dissipation capacity, good deformation self-recovery, crack self-closing ability, etc., and is used to cover the plastic hinge area of the concrete column to significantly improve the seismic performance of the concrete column and provide the concrete with significant self-recovery ability.
[0006] The second object of the present invention is to provide a construction method for a concrete column with a SMAF-ECC shell covering a plastic hinge zone, which is simple in construction and easy to implement and promote.
[0007] The scheme adopted by the present invention to achieve one of the purposes is: a concrete column with a SMAF-ECC shell covering a plastic hinge area, comprising a foundation and a column body fixed to the foundation, the column body comprising a steel skeleton, concrete and a shell wall, the column body is divided into a column body upper column and a column body lower column, the core area of the plastic hinge area of the column body lower column is cast with cast-in-place concrete, the shell wall of the plastic hinge area of the column body lower column is cast and formed by SMAF-ECC cement matrix, and the SMAF-ECC cement-based material is a composite fiber cement-based material made by adding superelastic shape memory alloy fiber SMAF with a volume ratio between 0.5% and 1% to ECC cement-based material.
[0008] Preferably, the steel skeleton includes a plurality of longitudinal bars arranged at intervals, each longitudinal bar is bound together by stirrups, the stirrups at both ends of the longitudinal bars are densely arranged, and the longitudinal bars are L-shaped, and the L-shaped longitudinal bars are bound to the steel bars in the foundation.
[0009] Preferably, the stirrups at the plastic hinge area of the lower column of the column shaft are densely arranged, and the upper column of the column shaft includes a non-densified arrangement area in the middle and a densely arranged area at the top.
[0010] Preferably, the shell wall of the column on the column shaft is cast by the concrete.
[0011] Preferably, the superelastic shape memory alloy fiber includes at least one of nickel-titanium-based SMAF and copper-based SMAF.
[0012] Preferably, the SMAF terminal is of N type.
[0013] Preferably, the thickness of the SMAF-ECC shell wall is not less than twice the distance from the center of the longitudinal reinforcement to the outer surface of the column.
[0014] Preferably, the SMAF-ECC cement-based material includes water, fine sand, gel material, water reducing agent, SMAF and auxiliary fibers, the SMAF and auxiliary fibers are randomly distributed in the cement-based material according to the designed volume ratio, and the auxiliary fibers are any one or both of polyvinyl alcohol fibers or polypropylene fibers.
[0015] The present invention proposes a new type of concrete column: a SMAF-ECC shell-wrapped plastic hinge area concrete column, which uses high-performance SMAF-ECC to replace part of the concrete to wrap the plastic hinge area of the concrete column. This new type of concrete column can not only significantly improve the seismic performance, but also has good self-recovery ability, providing a new method for achieving "tough" structures.
[0016] SMAF applied to concrete structures can significantly improve the structural energy dissipation and self-reset ability. However, due to the inherent brittleness of concrete and the incompatibility with SMAF deformation, the SMAF energy dissipation and deformation recovery performance cannot be effectively exerted. Using ECC instead of concrete as the matrix material of SMAF can make the deformation of the two materials more coordinated, which is more conducive to the full play of the performance of SMAF materials, provide deformation recovery ability for ECC, and solve the problem of residual deformation of ECC after earthquake. Studies on the use of SMAF-ECC in columns, bridge piers, beams, frame nodes and shear walls have shown that the combination of SMAF and ECC can form complementary material advantages and effectively realize the seismic energy dissipation, self-reset ability and damage repair function of the structure.
[0017] Due to its excellent tensile strain hardening characteristics and multiple tensile fine cracking behavior, ECC has been used by many scholars in concrete structures and its seismic performance has been analyzed. So far, there have been a large number of studies on the seismic performance of concrete structural components using ECC, and it has been shown that the seismic performance has been significantly improved, mainly in terms of ductility, damage tolerance and energy dissipation. SMAF, as a superelastic alloy material, has been studied and applied by many scholars to bridge columns, foundation columns, frame node columns, steel-concrete columns, etc. Through research, it is found that the concrete columns with SMAF-ECC added in the plastic hinge area are better than traditional reinforced concrete columns, ultra-high performance concrete and pure ECC concrete columns. This new composite material can effectively exert the material properties of ECC and SMAF, and has the high ductility, high energy dissipation and multi-crack cracking characteristics of ECC; it can also use the superelasticity of SMAF to effectively restore the fine cracks generated in the ECC matrix and reduce residual deformation; and SMAF is evenly dispersed in the matrix material, which can constrain and repair the fine cracks of the matrix in different directions and different parts, and is very suitable for ECC materials with large-scale cracking. Using SMAF-ECC to wrap the plastic hinge area of concrete columns can provide better damage tolerance, higher shear bearing capacity and energy dissipation capacity; it can also replace part of the stirrups to play a lateral restraint role, effectively enhancing the rotational deformation capacity of the plastic hinge area at the column end.
[0018] The solution adopted by the present invention to achieve the second purpose is: a construction method of a concrete column with a SMAF-ECC shell covering a plastic hinge area, comprising the following steps:
[0019] Step 1: Tie the steel bars, locate the hollow position in the core area of the steel cage, and pour the foundation first;
[0020] Step 2: After the foundation is poured, place a smooth hollow partition at the hollow position, and then formwork the plastic hinge area of the column under the column shaft;
[0021] Step 3: pour concrete into the hollow diaphragm and pour SMAF-ECC composite material into the column formwork at the same time;
[0022] Step 4: After the plastic hinge area is poured, slowly pull out the hollow partition, align and position the upper column and the lower column on the column body, support the column on the column body, and fix it with the template of the lower column on the column body;
[0023] Step 5: Pour concrete on the remaining column body to form a concrete column with a SMAF-ECC shell enclosing the plastic hinge area.
[0024] Preferably, in step 4, the joint shape of the templates of the upper column and the lower column of the column shaft can be any one of a concave-convex shape, a zigzag shape, and a V-shape.
[0025] The present invention has the following advantages and beneficial effects:
[0026] The concrete column of the present invention replaces the concrete outside the plastic hinge area with a SMAF-ECC shell wall of a certain thickness, and the plastic hinge core area and other parts of the column body still use cast-in-place ordinary concrete. This structure can greatly reduce the amount of SMAF-ECC materials used, and the cost is controllable. Compared with replacing the plastic hinge area of the concrete column with SMAF-ECC materials as a whole, by using these materials only in the plastic hinge area, the overall cost can be reduced while ensuring the seismic performance.
[0027] When the SMAF in the SMAF-ECC shell wall of the present invention is effectively anchored in the ECC matrix, the SMAF can exert its self-recovery performance and provide restoring force for the ECC, which can significantly improve the seismic performance of the concrete column, provide significant self-recovery ability for the concrete, and reduce the post-earthquake repair cost.
[0028] The SMAF-ECC shell-coated concrete column of the present invention can optimize the formation mechanism of the plastic hinge, so that the plastic hinge develops more stably under the action of an earthquake and avoids brittle failure.
[0029] The SMAF-ECC shell of the present invention has high tensile strength, good ductility, strong energy dissipation capacity, good deformation self-recovery, crack self-closing ability, etc., and can be used to cover the plastic hinge area of the concrete column to significantly improve the seismic performance of the concrete column, and provide the concrete column with significant self-recovery ability, thereby realizing the "tough" structural design concept.
[0030] The construction method of the invention is simple and easy to implement and popularize. BRIEF DESCRIPTION OF THE DRAWINGS
[0031] Figure 1 A detailed diagram of the concrete column structure according to an embodiment of the present invention;
[0032] Figure 2 Schematic diagram of the N-type terminal SMAF used in the embodiment of the present invention;
[0033] Figure 3 It is a longitudinal section view of the lower column of the column shaft during the construction of the concrete column in an embodiment of the present invention.
[0034] Figure 4 is a schematic structural diagram of a joint in an embodiment of the present invention;
[0035] Figure 5 SMAF bonding-slip curves of different end types in the embodiments of the present invention and the comparative examples;
[0036] Figure 6 Schematic diagram of the drawing stress of SMAF with different end types in the embodiments of the present invention and the comparative examples.
[0037] In the figure: 1—concrete column; 2—column shell wall on the column body; 3—column shell wall below the column body; 4—longitudinal reinforcement; 5—stirrups; 6—foundation; 7—joint; 8—formwork of the column below the column body; 9—hollow partition. DETAILED DESCRIPTION
[0038] For a better understanding of the present invention, the following examples are provided to further illustrate the present invention, but the present invention is not limited to the following examples.
[0039] Embodiment 1:
[0040] like Figure 1 As shown, a concrete column 1 with a SMAF-ECC shell covering a plastic hinge zone comprises a foundation 6 and a column body fixed on the foundation 6, wherein the column body comprises a steel skeleton, concrete and a shell wall, and the column body is divided into an upper column of the column body and a lower column of the column body. The core area of the plastic hinge zone of the lower column of the column body is cast with cast-in-place concrete, and the shell wall of the plastic hinge zone of the lower column of the column body is cast and formed by a SMAF-ECC cement matrix to form a shell wall 3 of the lower column of the column body. The SMAF-ECC cement-based material is a composite fiber cement-based material made by adding superelastic shape memory alloy fiber SMAF with a volume ratio of 0.5% to the ECC cement-based material.
[0041] The steel skeleton includes a plurality of longitudinal bars 4 arranged at intervals, each of which is bound together by stirrups 5 , the stirrups 5 at both ends of the longitudinal bars 4 are densely arranged, and the longitudinal bars 4 are L-shaped, and the L-shaped longitudinal bars 4 are bound to the steel bars in the foundation 6 .
[0042] The stirrups 5 at the plastic hinge area of the lower column of the column body are densely arranged, and the upper column of the column body includes a middle stirrup 5 non-densified arrangement area and a densely arranged area at the top of the stirrup 5.
[0043] Before binding, the oil stains, rust stains and other contaminants on the surface of the steel bars should be cleaned to ensure the bonding strength between the steel bars and concrete.
[0044] Before binding, the base steel bars should be accurately positioned and fixed to ensure that they are accurately connected to the L-shaped longitudinal bars. During the binding process, the verticality and spacing between the longitudinal bars and the base steel bars should be strictly controlled to meet the design requirements.
[0045] The shell wall 2 of the column on the column shaft is formed by pouring the concrete.
[0046] The superelastic shape memory alloy fiber is a nickel-titanium-based SMAF.
[0047] like Figure 2 As shown, the SMAF terminal is of N type.
[0048] The thickness of the SMAF-ECC shell wall shall not be less than twice the distance from the center of the longitudinal reinforcement to the outer surface of the column.
[0049] The SMAF-ECC cement-based material comprises water, fine sand, gel material, water reducing agent, SMAF and auxiliary fibers. The SMAF and the auxiliary fibers are randomly distributed in the cement-based material according to a designed volume ratio, and the auxiliary fibers are polyvinyl alcohol fibers.
[0050] like Figure 3 As shown, the construction method of the concrete column of the SMAF-ECC shell covering the plastic hinge area of the embodiment includes the following steps:
[0051] Step 1: Tie the steel bars, locate the hollow position in the core area of the steel cage, and pour the foundation 6 first;
[0052] Step 2: After the foundation 6 is poured, a hollow partition 9 with a smooth surface is placed at the positioned hollow position, and then the plastic hinge area of the lower column of the column body is supported by formwork;
[0053] Step 3: pouring concrete into the hollow partition 9 and pouring SMAF-ECC composite material into the column formwork 8 at the same time;
[0054] Step 4: After the plastic hinge area is poured, the hollow partition 9 is slowly pulled out, the upper column and the lower column of the column are aligned and positioned, the column of the column is supported by formwork, and fixed with the template 8 of the lower column of the column;
[0055] Step 5: Pour concrete on the remaining column body to form a concrete column with a SMAF-ECC shell enclosing the plastic hinge area.
[0056] In step 4, the joint shape of the template of the upper column of the column body and the lower column of the column body can be any one of a concave-convex shape, a sawtooth shape, and a V shape. In this embodiment, the shape of the joint 7 is a sawtooth shape (such as Figure 4 shown).
[0057] In this embodiment, the hollow partition is a PVC hollow partition. During construction, a layer of oil is applied to the outer surface of the PVC hollow partition to ensure that the surface of the PVC hollow partition is smooth enough so that there is less friction between the PVC hollow partition and the concrete.
[0058] Example 2
[0059] The difference between this embodiment and embodiment 1 is that the SMAF-ECC cement-based material is obtained by adding 0.75% of SMAF by volume into the ECC cement-based material.
[0060] Comparative Example 1
[0061] The difference between this comparative example and Example 1 is that the plastic hinge area is cast with pure concrete without adding SMAF-ECC material.
[0062] Comparative Example 2
[0063] The difference between this comparative example and Example 1 is that the shell wall in the plastic hinge zone is cast with pure ECC without adding SMAF.
[0064] Comparative Example 3
[0065] The difference between this comparative example and Example 1 is that the SMAF terminal is a straight terminal.
[0066] Comparative Example 4
[0067] The difference between this comparative example and Example 1 is that the SMAF terminal is a curved terminal.
[0068] Comparative Example 5
[0069] The difference between this comparative example and Example 1 is that the auxiliary fibers in the ECC concrete are polypropylene fibers.
[0070] The data in Table 1 are the energy dissipation, residual deformation, ductility coefficient and bearing capacity of the concrete columns obtained in Example 1, Example 2 and Comparative Examples 1-5 as shown in Table 1:
[0071] Table 1
[0072] project Energy consumption (kN·mm) Residual deformation(mm) Ductility coefficient Bearing capacity(kN) Example 1 1672.97 34.28 4.21 20.98 Example 2 1580.46 31.71 4.96 19.75 Comparative Example 1 1113.54 49.12 2.96 18.36 Comparative Example 2 1230.03 44.25 3.49 19.12 Comparative Example 3 1433.32 37.07 4.29 19.96 Comparative Example 4 1568.56 35.56 4.50 20.04 Comparative Example 5 1559.29 36.19 4.32 20.07
[0073] The data in Table 2 are the tensile strength, ultimate strain and compressive strength of the matrix in Example 1, Example 2 and Comparative Examples 1-5 as shown in Table 2 below:
[0074] Table 2
[0075] project Tensile strength(MPa) Ultimate strain (%) Compressive strength(MPa) Example 1 4.51～4.86 5.26～5.34 43.49～48.33 Example 2 4.43～4.77 5.18～5.30 43.27～47.93 Comparative Example 1 1.97～2.01 / 19.7～20.1 Comparative Example 2 4.25～4.50 5.12～5.23 41.65～46.36 Comparative Example 3 4.31～4.57 5.16～5.28 43.88～47.54 Comparative Example 4 4.27～4.64 5.02～5.31 44.18～46.64 Comparative Example 5 3.96～4.10 4.92～5.09 40.69～43.97
[0076] The data in Table 3 are the elastic modulus, ultimate tensile strength, ultimate tensile strain and deformation recovery rate of SMAF in the present invention:
[0077] Table 3
[0078]
[0079]
[0080] Figure 5 SMAF bonding-slip curves of different end types in the embodiments of the present invention and the comparative examples; Figure 6 Schematic diagram of the drawing stress of SMAF with different end types in the embodiments of the present invention and the comparative examples.
[0081] From the data in Table 1, Table 2 and Table 3 and Figure 5 and Figure 6 It can be seen that:
[0082] Compared with SMAF and auxiliary fibers with other end forms, N-type end SMAF and polyvinyl alcohol fiber ECC have better energy dissipation capacity, lower residual deformation, larger ductility coefficient and higher bearing capacity; in terms of basic mechanical properties, they also have higher tensile strength, compressive strength and ultimate strain.
[0083] Since the SMAF-ECC shell wall has self-repairing capabilities, the columns can recover their mechanical properties more quickly after extreme disaster events such as earthquakes, reducing maintenance workload and costs.
[0084] SMAF-ECC cement-based materials have high tensile strength, good ductility, strong energy dissipation capacity, good deformation self-recovery and crack self-closing capabilities. They can be used to cover the plastic hinge area of concrete columns to significantly improve the seismic performance of concrete columns and provide them with significant self-recovery capabilities. They can also replace part of the stirrups to play a lateral restraint role and effectively enhance the rotational deformation capacity of the plastic hinge area at the column end.
[0085] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any ordinary technician in the industry can smoothly implement the present invention as shown in the drawings and described above. However, any equivalent changes, modifications and evolutions made by technicians familiar with the profession without departing from the scope of the technical solution of the present invention using the technical content disclosed above are all equivalent embodiments of the present invention. At the same time, any equivalent changes, modifications and evolutions made to the above embodiments based on the essential technology of the present invention are still within the protection scope of the technical solution of the present invention.
Claims
1. A concrete column with a SMAF-ECC shell covering a plastic hinge zone, characterized in that: The invention comprises a column body fixed on a foundation, wherein the column body comprises a steel frame, concrete and a shell wall, and the column body is divided into a column upper column and a column body. The core area of the plastic hinge area of the column lower column is cast with cast-in-place concrete, and the shell wall of the plastic hinge area of the column lower column is cast and formed by SMAF-ECC cement matrix. The SMAF-ECC cement-based material is a composite fiber cement-based material made by adding superelastic shape memory alloy fiber SMAF with a volume ratio between 0.5% and 1% to the ECC cement-based material.
2. The SMAF-ECC shell-coated concrete column of the plastic hinge zone according to claim 1, characterized in that: The steel skeleton includes a plurality of longitudinal bars arranged at intervals, each of which is bound together by stirrups, the stirrups at both ends of the longitudinal bars are densely arranged, and the longitudinal bars are in an L-shape, and the L-shaped longitudinal bars are bound to the steel bars in the foundation.
3. The SMAF-ECC shell-coated concrete column of the plastic hinge zone according to claim 2, characterized in that: The stirrups at the plastic hinge area of the lower column of the column body are densely arranged, and the upper column of the column body includes a middle stirrup non-densified arrangement area and a top stirrup dense arrangement area.
4. The SMAF-ECC shell-coated concrete column of the plastic hinge zone according to claim 1, characterized in that: The shell wall of the column on the column shaft is formed by pouring the concrete.
5. The SMAF-ECC shell-coated concrete column of the plastic hinge zone according to claim 1, characterized in that: The superelastic shape memory alloy fiber includes at least one of a nickel-titanium-based SMAF and a copper-based SMAF.
6. The SMAF-ECC shell-coated concrete column of the plastic hinge zone according to claim 1, characterized in that: The SMAF terminal is of N type.
7. The SMAF-ECC shell-coated concrete column of the plastic hinge zone according to claim 1, characterized in that: The thickness of the SMAF-ECC shell wall shall not be less than twice the distance from the center of the longitudinal reinforcement to the outer surface of the column.
8. The SMAF-ECC shell-wrapped concrete column of the plastic hinge zone according to claim 1, characterized in that: The SMAF-ECC cement-based material includes water, fine sand, gel material, water reducing agent, SMAF and auxiliary fibers. The SMAF and auxiliary fibers are randomly distributed in the cement-based material according to the designed volume ratio. The auxiliary fibers are any one or two of polyvinyl alcohol fibers or polypropylene fibers.
9. A construction method for a concrete column with a SMAF-ECC shell covering a plastic hinge zone according to any one of claims 1 to 8, characterized in that: The following steps are involved: Step 1: Tie the steel bars, locate the hollow position in the core area of the steel cage, and pour the foundation first; Step 2: After the foundation is poured, place a smooth hollow partition at the hollow position, and then formwork the plastic hinge area of the column under the column shaft; Step 3: pour concrete into the hollow diaphragm and pour SMAF-ECC composite material into the column formwork at the same time; Step 4: After the plastic hinge area is poured, slowly pull out the hollow partition, align and position the upper column and the lower column on the column body, support the column on the column body, and fix it with the template of the lower column on the column body; Step 5: Pour concrete on the remaining column body to form a concrete column with a SMAF-ECC shell enclosing the plastic hinge area.
10. The construction method of a concrete column with a SMAF-ECC shell covering a plastic hinge zone according to claim 9, characterized in that: In step 4, the joint shape of the templates of the upper column on the column body and the lower column on the column body can be any one of a concave-convex shape, a zigzag shape, and a V shape.