KR101070043B1 - Column-type damper for improving earthquake-proof efficiency - Google Patents

Abstract

The present invention relates to a damper in the form of a column for improving the seismic performance of a building, and the slab of the building by reinforcing the strain hardening cement composite material in which 1.5 to 3.5 vol. Of fiber is added to 100 vol. Of cement paste or cement mortar. Column structure installed in the form of a column between; Reinforcing part connecting the column structure and the slab; And a plurality of bolts fixing the reinforcement parts to the column structures and the slabs, respectively. According to the present invention, it is possible to resist the compressive lateral force greater than the design value applied to the building in the event of an earthquake, and to absorb damage and impact energy according to the advantage to exhibit a significantly improved seismic performance for the building There is this.

Seismic resistance, column, damper, strain hardening cement composite, fiber

Description

COLUMN-TYPE DAMPER FOR IMPROVING EARTHQUAKE-PROOF EFFICIENCY}

The present invention relates to a damper in the form of a column for improving the seismic performance of a building, and more particularly, to the seismic performance of a building that can improve the seismic performance of a building by adding micro and macro fibers to a cement paste or cement mortar. A damper in the form of a column for improvement.

Currently, passive concept structural systems are designed to perform their intended functions under external influences (load and environmental impacts) considered during the design phase. Therefore, if a large safety factor is not taken into account to reflect the uncertainty of external factors, there is a limit that it cannot function under an unexpected load at the design stage and may cause social loss.

In addition, the seismic elements designed according to the current seismic design concept must be dissipated in the structure as plastic deformation after the yielding of the flexural reinforcement, even under the seismic load of the size reflected in the design stage. Therefore, even after the earthquake within the design load damage to the structure is inevitable, there was a problem that requires a lot of restoration cost for the reuse of the structure after the earthquake.

In particular, the current seismic design regulations have been revised based on lessons learned from past earthquake damage. Therefore, the fact that structures designed according to the previous seismic regulations are generally less safe for earthquakes than structures designed according to the current seismic regulations. The same has been proven in many past earthquakes.

On the other hand, an intelligent, active, or smart system in a structure, by itself, heals the damage of the structure caused by the constant load to increase the life span and usability of the structure, and also unexpected It is defined as a structural system that allows structures to behave safely without collapsing even under the influence of strong loads. In order to be applied to such a structural system, research on the development of intelligent structural materials that can reduce damage and control the damage even under earthquake loads within or above the design load and the development of utilization technology that can be applied to the structure are required. It is becoming.

However, due to the low tensile deformation capacity of concrete currently used in the construction field, damage such as cracking occurs before the action of the load or under a low load, and repair is required, and brittleness of the cement composite due to the low tensile deformation capacity is required. In recent earthquake cases, many of the structures have caused rapid collapse of many buildings and bridges, resulting in many economic losses.

And one of the major challenges facing the national and construction industry today is the deterioration of construction structures, and the cost of building infrastructure maintenance has risen from 8% of new construction costs in 2000 to 27.3% by 2007. As such, the maintenance cost of infrastructure takes up a large part of the national economic cost and is gradually increasing, so the development of new long-life, low-cost construction materials and structural systems will play an important part in the economic well-being of the next generation in Korea. Judging.

Therefore, the present invention has been developed as a part of the research to solve the conventional problems as described above, the object of the present invention is to improve the seismic performance of the building that can suppress or delay the occurrence of cracking under design load or unexpected additional load To provide a damper in the form of a pillar.

According to a feature of the present invention for achieving the above object, the first invention relates to a damper in the form of a column for improving the seismic performance of the building, 1.5 to 3.5 parts by volume with respect to 100 parts by volume of cement paste or cement mortar Column structure is installed in the form of a column between the beam or slab of the building by reinforcing the strain-hardening cement composite material added with fiber; Reinforcing portion connecting the column structure and the beam or slab; And a plurality of bolts for fixing the reinforcing part to the column structure and the beam or the slab, respectively, wherein the cement paste or cement mortar is water of 45 to 80 with respect to 100 parts by weight of ordinary portland cement or crude portland cement and admixture. Part by weight, 0.001 to 1.0 parts by weight of a high performance water reducing agent, the admixture is composed of 0.001 to 20 parts by weight of silica fume, 0.001 to 50 parts by weight of fly ash and 0.001 to 50 parts by weight of blast furnace slag powder, based on 100 parts by weight of the cement. The methyl cellulose thickener is mixed in an amount of 0.001 to 1.5 parts by weight based on 100 parts by weight of the cement, admixture, water, and a high-performance reducing agent, and the deformation-hardening cement composite material is contained in an amount of 5 to 100 parts by weight of the cement paste or cement mortar. It is characterized in that the 15 aggregates of fine aggregates are further mixed.

According to a second aspect of the present invention, in the first invention, the columnar structure includes: a base portion installed at an upper end of a beam or slab in a lower layer, at least one pillar portion installed vertically in the base portion, Characterized in that it consists of an upper end coupled to the bottom of the upper beam or slab.

The third invention, in the second invention, the fiber is a microfiber having a diameter of 10 ~ 15 ㎛ range and a length of 10 ~ 20mm range, and a diameter of 390 ~ 420 ㎛ and a length of 25 ~ 40 mm range Croissant fiber is characterized in that it is mixed in a ratio of 1.0: 0.1 to 1.0.

In a fourth invention, in the third invention, the microfiber is made of polyethylene, and the macrofiber is made of steel cord.

The fifth invention, in any one of the first to fourth invention, the steel is characterized in that the PS steel wire, shape memory alloy or reinforcing bar.

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The damper in the form of a column for improving the seismic performance of the building according to the present invention can suppress or delay the occurrence of cracking even under design loads or unexpected additional loads, thereby greatly improving permeability and durability, and dissipating energy and Damage control ability is greatly improved compared to the existing cement composite.

Therefore, according to the present invention, it is possible to heal the damage of the building caused by the constant load by itself, to increase the lifespan and usability of the building, and to resist the external influence even under the action of unexpected strong load, the building does not collapse and behaves safely. can do.

Due to these characteristics, the present invention can resist the compressive lateral force greater than the design value applied to the building during an earthquake, and can absorb damage and impact energy accordingly, thereby exhibiting a significantly improved seismic performance for the building. There is an advantage.

Hereinafter, with reference to the accompanying drawings with respect to the damper in the form of a column for improving the seismic performance of the building according to the present invention will be described.

1 is a side cross-sectional view showing a schematic configuration of a column-type damper for improving the seismic performance of the building according to the invention, Figure 2 is a view showing the reinforcement shape of the columnar structure shown in Figure 1, Figure 3 2 is a cross-sectional view taken along line AA ′ of FIG. 2, and FIG. 4 is a cross-sectional view taken along line B-B ′ of FIG. 2. In addition, Figure 5 is a block diagram illustrating a state in which a column-type damper is installed in the building to improve the seismic performance of the building according to the invention.

As shown here, the present invention is largely composed of a columnar structure 10, the reinforcing portion 20 and the bolt (30).

The columnar structure 10 is installed in the form of a column between the slabs (41, 43). The column structure 10 may be configured in various forms, in this embodiment, the base portion 11 is installed on the top of the slab 41 of the lower layer, and is installed in the vertical direction to the base portion 11 One or more pillar portions 13 and the pillar structure 10 is formed of the upper end portion 15 is installed on the upper end of the pillar portion 13 is coupled to the lower end of the slab 43 of the upper layer.

The columnar structure 10 functions as a vibration damping structure that prevents collapse of a building against lateral loads caused by earthquakes, and the total cross-sectional area is determined according to the design value of the lateral loads that can be tolerated. Accordingly, in consideration of the design value of the lateral load, the columnar structure 10 including the pillar portion 13 may be manufactured as shown in FIGS. 5A to 5C.

That is, as shown in Fig. 5 (a), it is possible to resist against the compressive lateral force in the event of an earthquake at both ends of the beam 45 of each layer, or as shown in Fig. 5 (b), the whole pillar Installed in the center of the beam 45 to serve as may be configured to simultaneously increase the compression performance and the resistance to the lateral force. Alternatively, as shown in (c) of FIG. 5, it may be provided to absorb damage and impact energy in the columnar structure 10 itself against shear force generated in the ground during a lateral load action such as an earthquake by installing at the lowest floor of the building. .

The base portion 11, the pillar portion 13 and the upper end portion 15 of the columnar structure 10 is preferably manufactured integrally, the material is made of cement paste or cement mortar, fibers and steel.

The cement paste or cement mortar is mixed with 45 to 80 parts by weight of water and 0.001 to 1.0 parts by weight of a high performance water reducing agent with respect to 100 parts by weight of ordinary portland cement or crude steel portland cement. And the admixture is composed of 0.001 to 20 parts by weight of silica fume, 0.001 to 50 parts by weight of fly ash and 0.001 to 50 parts by weight of blast furnace slag powder, based on 100 parts by weight of the cement, 100 parts by weight of the cement, admixture, water and high performance water reducing agent The methylcellulose thickener is added in an amount of 0.001 to 1.5 parts by weight based on the parts.

In more detail, in order to improve the strength properties and workability of the matrix, silica fume, fly ash and blast furnace slag powder, which are industrial by-products, are 0.001 to 20 parts by weight, 0.001 to 50 parts by weight and 0.001 to 100 parts by weight of cement, respectively. Mix 50 parts by weight. In addition, water is used in 45 to 80 parts by weight, and preferably 50 to 60 parts by weight based on 100 parts by weight of cement and admixture. In addition, the high performance water reducing agent is used in an amount of 0.001 to 1.0 parts by weight based on 100 parts by weight of the cement and the admixture in order to improve the fluidity of the strain hardening cement composite material. In addition, the methyl cellulose thickener for uniform dispersion of the fibers and to ensure the viscosity of the matrix is mixed in an amount of 0.001 to 1.5 parts by weight based on 100 parts by weight of the cement, admixture, water and high-performance reducing agent.

On the other hand, the fine aggregate is generally used No. 7 and No. 8 silica sand, it is preferable to use 1 to 30 parts by volume, preferably 5 to 15 parts by volume with respect to 100 parts by volume of cement mortar. In addition, as fine aggregates, steel sand or sea sand of 2.5 mm or less of the KS standard may be used, and in this case, 1 to 20 parts by volume, preferably 5 to 10 parts by volume, is used with respect to 100 parts by volume of cement mortar.

In addition, as short fibers, polyethylene fibers (PE), which are micro fibers, and steel cord fibers (SC), which are macro fibers, are mixed and used. The fiber is a cross-linking of the short fibers when the tensile force is applied to the cement composite to redistribute the stress to complement the brittle characteristics of the cement composite and suppress the sudden occurrence of damage. The reason why the microfibers and the macrofibers are mixed is used because the microfibers alone do not crosslink with each other when the macrocrack occurs.

As such, for short crosslinking of the matrix cracks, the short fibers are used in an amount of 1.5 to 3.5 parts by volume, preferably 2.5 to 3.5 parts by volume, based on 100 parts by volume of cement paste or cement mortar. At this time, the polyethylene fiber, which is a microfiber, has a diameter in the range of 10 to 15 µm and preferably has a length of 10 to 20 mm. In addition, the steel cord fibers, which are macro fibers, preferably have a diameter in the range of 390 to 420 μm and a length in the range of 25 to 40 mm. In addition, the mixing ratio of the polyethylene fiber and steel cord fiber is preferably in the ratio of 1.0: 0.1 ~ 1.0 in consideration of ease of pouring.

The above-mentioned hardening cement composite material is reinforced with steel materials. Steel may be selected in consideration of the lateral load received by the columnar structure 10, in general, PS steel wire, shape memory alloy or reinforcing bar may be used. In this embodiment, the case where the reinforcing bar 17 is used is illustrated.

When the reinforcing bar 17 is used as in the present embodiment, the reinforcing bar 17 may be reinforced as shown in FIGS. 2 to 4. That is, the main root 17a of 22 mm in diameter is arrange | positioned at the base part 11 and the upper end part 15, and the root 17b of diameter 16mm is arrange | positioned at 65 mm intervals around the said main root 17a. The pillar 13 has a 19 mm main root 17c extending to the base 11 and the upper end 15 and arranged around the main root 17c with a rib 10d having a diameter of 10 mm. 13 is arranged at intervals of 150 mm and the base 11 and the upper end 15 at intervals of 75 mm.

Meanwhile, as shown in FIG. 1, the reinforcing part 20 connects the columnar structure 10 and the slabs 41 and 43. More precisely, the reinforcement part 20 is connected to the base 11 of the columnar structure 10 and the bottom surface of the lower slab 41, and the upper end 15 and the upper layer slab of the columnar structure 10. Connect to the ceiling of (43). At this time, the upper end portion 15 is preferably connected to the upper slab 43 through the beam 45 which is a structure connecting the pillar and the pillar, in this case, the reinforcement portion 20 of the beam 45 The top surface 15 of the columnar structure 10 and the ceiling surface of the slab 43 is connected via the side surface.

The reinforcement part 20 is made of an iron plate having a predetermined thickness, the thickness of the reinforcement part 20 is greater than the tensile force and shear force necessary to integrally move the column structure 10 with the building in the event of a lateral load such as an earthquake. Designed to work. However, in the absence of accurate statistics or calculated values of tensile and shear forces generated, it is generally desirable to design the reinforcement 20 to have a thickness of 30 to 50 mm.

In addition, the reinforcing portion 20 is mounted to the columnar structure 10 and the slabs (41, 43) by bolts (30). At this time, the strength and number of bolts 30 for mounting the reinforcement part 20 to the columnar structure 10 and the slabs 41 and 43 are calculated by calculating the tensile force and the shear force that the bolt 30 must bear. The strength and number of 30 are determined. At this time, the design separation strength for the tensile force of one bolt 30, the design sliding strength for the shear force is calculated by the following equation.

First, the design separation strength φS _t for the tensile force in one bolt 30 is calculated as shown in [Equation 1].

Where A _b is the nominal cross-sectional area (mm 2) of the high-strength bolt and F _st is the spacing strength (N / mm 2) of the high-strength bolt.

In addition, the design sliding strength (φS _t ) for the shear force in one bolt 30 is calculated as shown in [Equation 2].

Where n is the shear surface number, A _b is the nominal cross-sectional area of the high-strength bolt (mm 2), and F _ss is the sliding strength (N / mm 2) of the high-strength bolt.

On the other hand, the separation strength and sliding strength of the high-strength bolt 30 by steel type can be taken from the values shown in [Table 1].

F8T F10T F13T Separation Strength (F _st ) 370 455 590 Slip strength (F _ss ) 175 220 285

Next, when the tensile force and the shear force are simultaneously received, the design sliding strength (φS _t ) for one shear force of the high-strength bolt is calculated as shown in [Equation 3].

Where P _t is the tensile force kN acting on the bolt (but Pt <φ F _st A _b ), and T ₀ is the design bolt tension (kN).

Next, the characteristics of the columnar structure according to the present invention will be described.

6 is a side view showing a configuration for testing the characteristics of the columnar structure according to the present invention.

As shown, the base portion 11 of the columnar structure 10 was tightly connected using a steel bar 51 to the reaction slab 47 so as to be in a completely fixed state, and the buckling preventing beam and ball jig were formed on the lateral load line. A beam & ball jig) 53 was provided to prevent out-of-plane buckling while lateral loads were applied. Lateral load was controlled by the member angle (lateral displacement / height of the column structure) by using an actuator 55 of 1000kN capacity installed on the reaction wall. It was.

And in order to contrast with the columnar structure 10 according to the present invention, the same rebar reinforcement with the columnar structure 10 shown in Figures 2 to 4 and made a comparative example using a general concrete experiment in the same manner as described above It was.

Experiment results for this are as shown in FIGS. 7 to 10.

In more detail, Figure 7 is a graph showing the load-displacement relationship curve of the Examples and Comparative Examples. In the drawing, the left vertical coordinate represents Load in kN units, and the lower horizontal coordinate represents Displacement in mm units.

As shown in (a) of FIG. 7, in the comparative example, the maximum load was 551.01 kN (R = 1.61%), where R represents a rotation angle, and then 80% of the maximum strength. It has a ductility ratio of 1.267 up to 440.81 kN (R = 2.04%).

On the other hand, as shown in Figure 7 (b), the maximum load of this embodiment is 773.74 kN (R = 2.77%) it can be seen that the 40.42% yield strength compared to the comparative example. In addition, in the Example, the ductility ratio was 1.292 up to 637.73 kN (R = 3.58%), which is 80% of the maximum strength, and increased by 1.97% compared with the comparative example.

This is due to the crosslinking effect of the fiber, it is judged that there is an effect of improving the ductility of the member according to the fiber reinforcement.

In addition, the damage stages evaluated on the basis of the external damage such as the crack of the specimen in the load-displacement relationship curve are shown as Romans I, II, III, IV, and V. According to the EERI damage level definition, In the examples, it is evaluated to the extent that repair is possible within the degree of damage.

Next, Figure 8 is a graph showing a comparison of the load and shear strain and shear strain applied to the comparative example and the embodiment.

In the comparative example of FIG. 8 (a), the positive (+) and negative (-) shear strains were almost symmetrical. In the example of FIG. 8 (b), the positive (+) shear strains were relatively Appeared small. This is determined by the fact that the end part is locally broken during positive (+) pressing force.

In addition, the maximum shear strains of Comparative Examples and Examples were 0.38% and 0.71%, respectively. This is because the embodiment has a softer behavior than the comparative example, and it is determined that the shear deformation is suppressed due to the crosslinking action of the reinforcing fibers in the cement composite.

Next, Figure 9 is a graph showing the residual energy, Figure 9 (a) is shown by comparing the crack width increase and the residual energy in the Comparative Example and Example according to the cycle progress, Figure 9 (b) is a cycle Residual energy in the comparative example and the example according to the progress is compared.

As shown in (a) of FIG. 9, the residual energy in the comparative example was somewhat larger within the crack width of 1 mm, but the fracture energy was shown to decrease rapidly after the crack width of 1 mm. On the other hand, in the case of Example, it was found to be stable while preserving 20% or more of residual energy up to 3 mm in crack width.

In addition, the seismic performance reduction coefficient (ŋ) was calculated based on the final cumulative energy dissipation capacity of Comparative Examples and Examples. As shown in (b) of FIG. 9, after 10 cycles, the seismic performance was greatly increased. In the case of Example, it was found that even after 20 cycles, more than 70% of the total seismic performance was secured. Therefore, in the case of experiencing the same earthquake damage, it is determined that the residual energy capacity of the member can be preserved by exhibiting a breakthrough energy absorption capacity in the embodiment.

Next, FIG. 10 is a graph comparing the relationship between the damage stage and the crack width in the comparative example and the example.

As shown, cracks of 0.4 mm or more classified as structural cracks occurred at 0.4% of the member angles in the comparative example, but reached 2.0% of the member angles in the examples reinforced with hybrid fibers (PE + SC). In addition, the crack width at the final failure of the comparative example (R = 2.0%) was 3.0 mm, and the crack width at the same member angle (R = 2.0%) of the example was 0.4 mm, indicating about 13.3% of the comparative example. In the final failure of the example, the crack width of 3.6 mm was found at 3.4% of the member angle. This is believed to be because the reinforcing fibers hybridized in the examples inhibited micro and macro cracks, respectively.

As described above, the embodiment according to the present invention can be seen that the physical performance is significantly improved compared to the comparative example by the existing concrete. Therefore, if the embodiment is used as the seismic structure of the building, as illustrated in Figs. 5A to 5C, it is expected that the seismic performance of the building can be improved.

The rights of the present invention are not limited to the embodiments described above, but are defined by the claims, and those skilled in the art can make various modifications and adaptations within the scope of the claims. It is self-evident.

That is, the reinforcement part 20 and the bolt 30 in the present invention, the anchor is embedded in the base and the upper end of the column structure 10, and replaced with anchor bolts are buried in advance in the slab of the building and coupled with the anchor Can be. In this case, the size and number of anchors and anchor bolts may be determined and used in the same manner as the reinforcing steel plate and bolts described above.

1 is a side cross-sectional view showing a schematic configuration of a damper in the form of a column for improving the seismic performance of a building according to the present invention;

Figure 2 is a view showing the shape of the reinforcement of the columnar structure shown in Figure 1,

3 is a cross-sectional view taken along line AA ′ of FIG. 2;

4 is a cross-sectional view taken along line BB ′ of FIG. 2;

5 is a configuration diagram illustrating a state in which a damper of a pillar shape for improving the seismic performance of the building according to the present invention installed in the building,

Figure 6 is a side view showing a configuration for testing the characteristics of the columnar structure according to the present invention,

7 is a graph showing a load-displacement relationship curve of an example and a comparative example,

8 is a graph comparing loads and shear strains and shear strains applied to Comparative Examples and Examples;

9 is a graph showing residual energy,

10 is a graph comparing the relationship between the damage stage and the crack width in Comparative Examples and Examples.

<Code Description of Main Parts of Drawing>

10: pillar structure 11: foundation

13: pillar portion 15: upper portion

20: reinforcement part 30: bolt

Claims (6)

Column structure is installed in the form of a column between the beam or slab of the building by reinforcing the strain-hardening cement composite material added 1.5 ~ 3.5 volume of fiber to 100 parts by volume of cement paste or cement mortar with steel; Reinforcing portion connecting the column structure and the beam or slab; And And a plurality of bolts fixing the reinforcement to the column structure and the beam or the slab, respectively. The cement paste or cement mortar is mixed 45 to 80 parts by weight of water, 0.001 to 1.0 parts by weight of a high performance water reducing agent with respect to 100 parts by weight of ordinary Portland cement or crude steel portland cement, the admixture is 100 parts by weight of the cement It is composed of 0.001 to 20 parts by weight of silica fume, 0.001 to 50 parts by weight of fly ash and 0.001 to 50 parts by weight of blast furnace slag powder, and 0.001 to 1.5 parts by weight of methylcellulose thickener based on 100 parts by weight of the cement, admixture, water and high performance water reducing agent. Made by mixing The deformation-type cement composite material, the damper in the form of a pillar for improving the seismic performance of the building, characterized in that 5 to 15 parts by volume of the aggregate aggregate with respect to 100 parts by volume of the cement paste or cement mortar. The method of claim 1, The pillar structure may include a base installed at an upper end of a lower beam or slab, at least one pillar installed vertically in the base, and an upper end installed at an upper end of the pillar and coupled to a lower end of a beam or slab. A pillar-type damper for improving the seismic performance of the building, characterized in that consisting of. 3. The method of claim 2, The fibers are mixed with microfibers having a diameter in the range of 10 to 15 μm and lengths of 10 to 20 mm, and macrofibers having a diameter of 390 to 420 μm and a length of 25 to 40 mm in a ratio of 1.0: 0.1 to 1.0. A pillar-shaped damper for improving the seismic performance of the building, characterized in that consisting of. The method of claim 3, The microfiber is made of polyethylene, the macrofiber is made of a steel cord, characterized in that the pillar-shaped damper for improving the seismic performance of the building. The method according to any one of claims 1 to 4, The steel material is a PS steel wire, a shape memory alloy or a reinforcing bar-shaped damper for improving the seismic performance of the building, characterized in that the rebar. delete

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