CN112663682B - Square earthquake metasoma structure with cross-shaped cavity - Google Patents

Abstract

The invention discloses a square seismic metastructure with a cross-shaped cavity, which is formed by extending seismic metastructure unit cells in two mutually vertical directions in a horizontal plane and is designed on the periphery of a building foundation; the seismic metasoma unit cell comprises a concrete pile with a cross-shaped cavity, a rubber layer, a steel pipe layer and a soil layer. The concrete pile has a circular cross section, and a through-long cross-shaped cavity is arranged in the middle of the cross section. The rubber layer and the steel pipe layer are both round in cross section, the soil is square in cross section, and a round through hole is formed in the middle of the soil. The periodic structure is arranged along the circumferential direction of the building in a segmented mode within a certain range, and the band gap characteristic of the periodic structure is utilized to attenuate the seismic surface wave within the range of 6-17Hz, so that the building is protected from being damaged by the surface vibration caused by the seismic surface wave and other reasons.

Description

A Square Seismic Metastructure with a Cross-shaped Cavity

technical field

The invention relates to a square seismic metastructure with a cross-shaped cavity, which is a new structure with good control and attenuation for seismic surface waves.

Background technique

There are millions of earthquakes every year around the world, the vast majority of which are below magnitude 3.9, but more than 1,000 earthquakes with magnitudes above 5.0. Ground vibrations caused by even minor earthquakes can have an impact on the structural integrity of a building. Furthermore, for structures such as nuclear power plants and oil refineries, even a small amount of damage can have catastrophic consequences. Seismic waves mainly include surface waves and body waves, among which the seismic surface waves cause the most damage and travel the farthest. Therefore, it is of great interest to design a defensive structure to prevent seismic surface waves from harming buildings, especially for long waves with frequencies in the 0.1-20 Hz range, as this includes the fundamental resonance frequency of many buildings and structures. At present, it is still very difficult to formulate corresponding protection measures for such long-wavelength and low-frequency seismic surface waves. At the same time, the development of corresponding protection devices is still an open issue.

Among passive control measures, frequency modulated mass damper TMD is an effective structural vibration control device. The tuned mass damper is to make the TMD system and the structure resonate by adjusting the frequency ratio and damping ratio of the TMD system. According to the conservation of energy, the vibration of the TMD system will dissipate part of the energy, reducing the response of the main structure. However, TMD can only control the vibration in a certain mode, has narrow-band characteristics, and is very sensitive to the fluctuation of the natural frequency of the structure. Therefore, to invent a shock absorbing structure or device with simple structure and strong adaptability, which can effectively control and attenuate low-frequency seismic surface waves, it will be useful for protecting urban buildings and other vibration-sensitive structures, such as precision laboratories, nuclear power plants, and ancient buildings. of great significance! Recently, the emergence of seismic metastructures provides a new idea for seismic protection. Seismic metastructures are periodic structures based on phononic crystal theory with band gap properties. In the bandgap frequency range, seismic waves cannot pass through seismic metastructures. The present invention draws on the principle of phononic crystal to control mechanical waves, adopts concrete, steel pipe and rubber to form a shock absorbing structure to realize the control and attenuation of seismic waves.

SUMMARY OF THE INVENTION

The square seismic metastructure with cross-shaped cavity designed by the present invention relates to a seismic metastructure for attenuating seismic surface waves. The purpose is to provide a square seismic metastructure with a cross-shaped cavity, which can attenuate seismic surface waves in all directions and multiple angles, protect buildings, use simple materials, effectively reduce earthquake disasters, and reduce building post-disaster repair and maintenance costs.

The invention relates to a square seismic meta-structure with a cross-shaped cavity. The seismic meta-structure is composed of seismic meta-structure unit cells extending along two mutually perpendicular directions in a horizontal plane, and is designed on the foundation of a building. Periphery; the seismic metastructure unit cell includes a concrete pile 1 with a cross-shaped cavity, a rubber layer 2, a steel pipe layer 3 and a soil layer 4. The section of the concrete pile 1 is circular, and there is a long cross-shaped cavity in the middle of the section. The rubber layer 2 and the steel pipe layer 3 have circular cross-sections, and the soil 4 has a square cross-section with a circular through hole in the middle.

Concrete pile 1 with a cross-shaped cavity has a circular section radius of 0.68m and a height of 18m. There is a cross-shaped cavity in the middle composed of two rectangular through holes, each of which is 1.2m long, 0.2m wide and 18m high, and C20-C30 plain concrete is selected. The outer diameter of the rubber layer 2 is 0.7m, the inner diameter is 0.68m, and the height is 18m, and industrial rubber is selected. The steel pipe layer 3 has a radius of 0.8m on the outer side, a length of 0.7m on the inner side and a height of 18m. Hot-rolled seamless steel pipes are selected. Soil layer 4 has a square section with a side length of 2m, an inner circular hole with a radius of 0.8m and a height of 18m. The material is ordinary sandy soil.

The structure of the present invention is arranged below the ground surface around the building foundation, the top surface of the structure is flush with the ground surface, and is arranged along the circumferential direction of the building, with a horizontal distance of 6m from the building. The peripheral dimension of the periodic structure formed by the extension of the unit cell structure of the present invention is not less than the dimension of the foundation of the building.

The technical scheme of the present invention is:

A square seismic metastructure with a cross-shaped cavity is formed by the continuous extension of the designed seismic metastructure unit cell along two mutually perpendicular directions in the horizontal plane. It is arranged below the ground surface around the building foundation. At the same time, the top surface of the structure is flush with the ground. It is arranged in sections along the building ring within a certain range, using the band gap characteristics of the periodic structure to attenuate the seismic surface wave in the range of 6-17 Hz, and protect the building from the damage of the surface vibration caused by the seismic surface wave and other reasons.

When a seismic wave strikes, there will be a cross-shaped cavity between concrete, rubber and steel pipe in the seismic metastructure unit cell; vibration will occur between the unit cell and the unit cell, and the combined seismic metastructure will generate a band gap. , so as to effectively control and attenuate seismic surface waves and protect buildings.

The seismic metastructure unit cell with a cross-shaped cavity designed by the present invention is composed of a concrete pile 1 with a cross-shaped cavity, a rubber layer 2 , a steel pipe layer 3 and a soil layer 4 . On the outside of the concrete pile 1 , the rubber layer 2 is first covered. Then, the outside of the rubber layer 2 is covered with the steel pipe 3 , and finally the outside of the steel pipe 3 is filled with a soil layer 4 .

The cross-section of the concrete pile 1, the rubber layer 2 and the steel pipe layer 3 with the cross-shaped cavity is circular, and the cross-section of the soil layer 4 is square.

The three parts of the concrete pile 1, the rubber layer 2 and the steel pipe layer 3 with the cross-shaped cavity coincide with each other.

The concrete pile 1, the rubber layer 2 and the steel pipe layer 3 with the cross-shaped cavity have the same height and the upper and lower surfaces are on the same level.

The square seismic metastructure with cross-shaped cavity designed by the present invention is prepared by using different materials.

The materials of the square seismic metastructure with cross-shaped cavity designed by the present invention include concrete, rubber, steel and soil. Please refer to Fig. 2 and Fig. 3, wherein the density of the concrete pile ρ ₁ =2500 kg/m ³ ; Young's modulus E ₁ =4×10 ¹⁰ Pa; Poisson's ratio γ ₁ =0.2; the density of the rubber layer ρ ₂ =1300 kg/m ³ ; Young's modulus E ₂ =1.02×10 ⁵ Pa; Poisson's ratio γ ₂ =0.47; density of steel tube layer ρ ₃ =7850 kg/m ³ ; Young's modulus E ₃ =2.1× 10 ¹¹ Pa; Poisson's ratio γ ₃ =0.3; density of soil layer ρ ₄ =1800 kg/m ³ ; Young's modulus E ₄ =2×10 ⁷ Pa; Poisson's ratio γ ₄ =0.3. Made of four materials.

Compared with the TMD passive structure vibration reduction control method, the present invention has the following advantages:

1) Effectively control seismic surface waves in a wide frequency range. A square seismic meta-structure with a cross-shaped cavity designed by the present invention can effectively control and attenuate seismic surface waves in the range of 6-17 Hz, and can effectively protect various buildings whose resonance fundamental frequency is in this range.

2) Remote control and attenuation of seismic surface waves. The seismic metastructure designed by the invention is a periodic arrangement structure with band gap characteristics. It is arranged below the ground surface around the building foundation and is not connected to the building. Thus, seismic surface waves can be remotely controlled and attenuated before they reach the building.

3) Surface waves born from different reasons can be controlled. The seismic metastructure designed by the present invention can control the seismic surface wave in the full band gap range. It has an effective attenuation effect on all surface wave vibrations that appear in the full bandgap frequency range, such as human-induced vibration, piling, ground transportation and mechanical use on construction sites.

4) Simple structure. The seismic meta-structure designed by the present invention mainly consists of a concrete pile with a cross-shaped cavity, a rubber layer, a steel pipe layer and a soil layer, which form a unit cell, and then the unit cell is arranged in two mutually perpendicular directions in the same horizontal plane. Constructed by extension. The structure is simple.

5) It can be applied to different buildings with different site conditions. By considering factors such as site conditions in the region and the height of the protected buildings, and by adjusting and changing the geometric parameters and material parameters of each component of the seismic metastructure, it can be applied to various geological conditions and different buildings.

6) All building structures in the entire area can be protected. The seismic metastructure involved in the present invention can not only protect a single building, but also protect all buildings and other public facilities in the whole area, such as parks, squares and the like.

7) The materials are common. The square seismic metastructure with a cross-shaped cavity designed by the present invention uses four materials: steel, rubber, concrete and soil. These materials are commonly used in building construction and are readily available.

8) All-round and effective protection of buildings. The seismic metastructure designed by the present invention is arranged around the building foundation and along the building segmented circumferential direction, which can effectively protect the building in all directions against the seismic surface waves randomly appearing in different directions.

Description of drawings

FIG. 1 is a schematic diagram of the layout of the seismic metastructure provided by the present invention.

FIG. 2 is a schematic diagram of a square seismic metastructure unit cell with a cross-shaped cavity provided by the present invention.

FIG. 3 is a schematic top view of a square seismic metastructure unit cell with a cross-shaped cavity provided by the present invention.

FIG. 4 is an energy band structure diagram of a square seismic metastructure with a cross-shaped cavity provided by the present invention.

5 is the transmission spectrum of the seismic metastructure composed of ten rows of seismic metastructure unit cells with cross-shaped cavities when Rayleigh waves are excited along the ΓХ direction provided by the present invention.

Among them: 1. Concrete pile with cross-shaped cavity; 2. Rubber layer; 3. Steel pipe layer; 4. Soil layer.

Detailed ways

Detailed embodiments of the present invention are given below in conjunction with the accompanying drawings.

In FIG. 1 , the arrangement of a square seismic metastructure with a cross-shaped cavity designed by the present invention is shown. A segmented annular arrangement is adopted, and the specific arrangement is shown in Figure 1.

In Figures 2 and 3, a square seismic metastructure unit cell with a cross-shaped cavity is shown, and its components include a concrete pile 1 with a cross-shaped cavity, a rubber layer 2, a steel pipe layer 3 and a soil layer 4.

The cross-section of the concrete pile 1 with a cross-shaped cavity is a circle with a cross-shaped through hole in the center. The outside of the concrete pile 1 is covered with a rubber layer 2 of a certain thickness. The steel pipe layer 3 is coated on the outside of the rubber layer 2 .

The three parts of the concrete pile 1, the rubber layer 2 and the hollow steel pipe 3 coincide with each other, and the upper and lower surfaces are flush with each other and have the same height.

The sections of the rubber layer 2 and the steel pipe layer 3 are both circular rings. The inner diameter and outer diameter of the rubber layer 2 are respectively the same as the outer diameter of the concrete pile 1 and the inner diameter of the hollow steel pipe 3 . The inner wall and outer wall of the rubber layer 2 are tightly connected with the outer wall of the concrete pile 1 and the inner wall of the hollow steel pipe 3 respectively. The concrete pile 1 with a cross-shaped cavity, the rubber layer 2 and the steel pipe layer 3 constitute a composite round pile with a cross-shaped cavity.

After making a composite round pile with a cross-shaped cavity, repeat the above steps to make a plurality of composite round piles with the same cross-shaped cavity, the number of which can be at least arranged around the building in a segmented and annular direction as shown in Figure 1 .

Around the building, according to the position shown in Figure 1, the composite round piles with cross-shaped cavities are arranged in the circumferential direction below the ground surface around the building foundation, and the center spacing of the composite round piles is 2m. After the composite round piles are laid out, fill the soil between the composite round piles.

A square seismic metastructure with a cross-shaped cavity designed by the present invention, the radius of the concrete pile 1 is 0.68m, the longitudinal height is 18m, and the center has a cross-shaped cavity, and the cross-shaped cavity consists of two It is composed of through-holes perpendicular to each other. The size of each cuboid is 1.2m long, 0.2m wide and 18m high. C20-C30 plain concrete is selected. The outer diameter of the rubber layer 2 is 0.8m, the inner diameter is 0.68m, and the longitudinal height is 18m, and industrial rubber is selected. The outer diameter of the steel pipe layer 3 is 0.8m, the inner diameter is 0.7m, and the longitudinal height is 18m, and the hot-rolled seamless steel pipe is selected. Soil layer 4 has a square section with a side length of 2m, an inner cylindrical through hole with a radius of 0.8m and a height of 18m. The material is ordinary sandy soil. The above-mentioned concrete pile 1, rubber layer 2 and steel pipe layer 3, the composite round pile formed by the three and the outer soil layer 4 form a square seismic super-shape with a cross-shaped cavity with a size of 2m in length, 2m in width and 18m in height. Structural unit cell. The structure is arranged around the building foundation, and the top surface of the structure is flush with the ground surface.

The specific material parameters are:

Concrete: density ρ ₁ =2500 kg/m ³ ; Young's modulus E ₁ =4×10 ¹⁰ Pa; Poisson’s ratio γ ₁ =0.2;

Rubber: density ρ ₂ =1300 kg/m ³ ; Young's modulus E ₂ =1.02×10 ⁵ Pa; Poisson’s ratio γ ₂ =0.47;

Hollow steel pipe: density ρ ₃ =7850 kg/m ³ ; Young's modulus E ₃ =2.1×10 ¹¹ Pa; Poisson’s ratio γ ₃ =0.3;

Soil: density ρ ₄ =1800kg/m ³ ; Young's modulus E ₄ =2×10 ⁷ Pa; Poisson’s ratio γ ₄ =0.3.

Please refer to Figure 4, where the light gray area is the full bandgap range of the band structure. The band structure calculation found that the structure has a full band gap in the range of 6-17 Hz. Two full band gaps are found in the controllable attenuation seismic surface wave region of the seismic metastructure designed by the present invention, which are respectively located at: the first one: 6.82-12.80Hz; the second one: 14.24Hz-16.48Hz.

Please refer to Figure 5, where the light gray area is the attenuation area of the transmission spectrum. When the Rayleigh wave is excited along the ΓХ direction, it is found by calculating the transmission spectrum of the ten rows of square seismic metastructure unit cells with cross-shaped cavities designed in the present invention that the attenuation region calculated by the transmission spectrum is the same as the full band of the energy band structure. The gaps are basically coincident. This shows that the seismic metastructure designed in the present invention can effectively control and attenuate the seismic surface waves located in the full band gap frequency range.

To sum up, a square seismic metastructure with a cross-shaped cavity designed in the present invention has the characteristics of low frequency band gap, so that it can effectively control and attenuate the seismic surface waves in the frequency range of the full band gap, and has good attenuation. seismic performance and protection of buildings.

Claims (3)

1. A square seismic metastructure with a cross-shaped cavity is characterized in that: the seismic metasoma structure is formed by extending seismic metasoma unit cells in two mutually perpendicular directions in a horizontal plane, and is designed below the ground surface at the periphery of a building foundation, and the top surface of the structure is flush with the ground surface; the seismic metasoma unit cell comprises a concrete pile (1) with a cross-shaped cavity, a rubber layer (2), a steel pipe layer (3) and a soil layer (4); the section of the concrete pile (1) is circular, and a through long cross-shaped cavity is arranged in the middle of the section; firstly coating a rubber layer (2) outside the concrete pile (1), then coating a steel pipe layer (3) outside the rubber layer (2), and finally filling a soil layer (4) outside the steel pipe layer (3); when earthquake waves come, the concrete pile with the cross-shaped cavity in the seismic metasoma unit cell, the space between the rubber layer and the steel pipe layer, the unit cell and the unit cell vibrate, and the combined seismic metasoma structure can generate band gaps, so that the seismic surface waves are effectively controlled and attenuated, and the building is protected;

the sections of the rubber layer (2) and the steel pipe layer (3) are circular, the section of the soil layer (4) is square, and a circular through hole is formed in the middle of the soil layer (4);

the radius of the circular section of the concrete pile (1) with the cross-shaped cavity is 0.68m, and the height is 18 m; the middle of the concrete pile (1) is provided with a cross-shaped cavity consisting of two cuboid through holes, each cuboid through hole is 1.2m long, 0.2m wide and 18m high, and the concrete pile (1) is made of C20-C30 plain concrete; the outer radius of the rubber layer (2) is 0.7m, the inner radius is 0.68m, the height is 18m, and industrial rubber is selected; the outer radius of the steel pipe layer (3) is 0.8m, the inner radius is 0.7m, the height is 18m, and a hot-rolled seamless steel pipe is selected; the side length of the square cross section of the soil layer (4) is 2m, the radius of the internal circular through hole is 0.8m, the height is 18m, and the soil layer is made of common sandy soil.

2. A square seismic metastructure having a cross-shaped cavity according to claim 1, wherein: the concrete pile comprises a concrete pile body (1) with a cross-shaped cavity, a rubber layer (2) and a steel pipe layer (3), and the axle centers of the three parts are overlapped.

3. The square seismic metastructure having the cross-shaped cavity according to claim 1, wherein: the concrete pile comprises a concrete pile body (1) with a cross-shaped cavity, a rubber layer (2) and a steel pipe layer (3), wherein the heights of the three parts are the same, and the upper surface and the lower surface of the three parts are on the same horizontal plane.

Images