KR102115909B1 - Strengthening and Deformation Recovery Method using Characteristics of Recovery Stress of Iron based Shape Memory Alloly for Deteriorated Reinforced Concrete Structures in Use - Google Patents

Abstract

The present invention relates to a construction method for recovering cracks and deformation and reinforcing the load carrying capacity of an existing reinforced concrete structure using the recovery capability of an iron-based shape memory alloy. According to the present invention, the construction method for recovering cracks and deformation and reinforcing the load carrying capacity of an existing reinforced concrete structure using the recovery capability of an iron-based shape memory alloy comprises: an iron-based shape alloy reinforcement material preparing step; an existing concrete structure ground plane arranging step; and a construction completion step. According to the present invention, cracks or deformation of a concrete structure can be easily recovered.

Description

Strengthening and Deformation Recovery Method using Characteristics of Recovery Stress of Iron based Shape Memory Alloly for Deteriorated Reinforced Concrete Structures in Use}

In the present invention, the existing concrete structure is reinforced with an iron-based reinforcing alloy reinforcement when cracks and deformations occur during use and the load capacity decreases due to changes and necessity of environmental conditions, load conditions, use conditions, etc., and recovers stress by contact or non-contact heating method. It is related to a reinforcing method capable of recovering cracks, deformations, and load carrying capacity in an existing concrete structure to a desired degree.

The most widely used materials in civil engineering and architecture are steel and concrete. Steel is a high-strength material that can be obtained at low cost, and concrete is not only a low-cost high-compression material, but they also have good adhesion and similar thermal expansion coefficients, so they use steel and concrete to construct a durable, low-cost concrete structure. can do. The concrete structure may be deformed due to overload or environmental conditions during use.

There are various methods to reinforce the concrete structure when it is deformed.

First, as a method of reinforcing a concrete structure, a method of attaching a reinforcing material is most common. That is, it is a method to prevent the expected tensile or shear failure by attaching and reinforcing the reinforcement by attaching the reinforcement to the area where the flexural tensile force of the concrete structure is concentrated.

Reinforcing methods for attaching these reinforcing materials have various types of reinforcing materials and are applied in the field because the effect of reinforcing varies depending on the characteristics of the reinforcing materials. Typical examples include reinforcing methods by attaching steel sheets and special fiber materials. And a method of reinforcing.

Looking at each of the above examples, first, the method of attaching and reinforcing the steel sheet is the most commonly used method because the material cost is relatively inexpensive, but the weight of the steel sheet itself is heavy, so it is difficult to work in a narrow place such as the need to mobilize heavy equipment. There is a problem of corrosion of the steel sheet itself, which is a reinforcing material, crack generation at the steel sheet attachment site, deformation of the welding site, and crack fracture, so the reinforcing effect is temporary and the construction cost is high for each process.

Next, looking at a method of attaching and reinforcing a special fiber material, as a method of attaching and reinforcing a specially manufactured material to solve the problems caused by the above-mentioned steel sheet itself, it can be seen that the properties of the material enhance the effect of reinforcement. , Carbon fibers are the most representative of those used in construction sites in Korea.

The method of attaching and reinforcing the carbon fiber is a method of impregnating and attaching a carbon fiber sheet arranged in one direction to a portion to be reinforced using a primer and an epoxy adhesive, and a carbon fiber composite. It can be divided into a method of attaching with an epoxy adhesive.

First, in the method of attaching and reinforcing the carbon fiber sheet, the surface to be reinforced of the existing structure is treated, and the height of the construction surface is adjusted to apply the primer on the surface, and then the carbon fiber sheet is used using an epoxy adhesive. It is a method of bonding and impregnating the surface of the carbon fiber sheet with a top coat again. As a method that can be performed manually without mobilizing additional heavy equipment, the material has advantages such as no corrosion and excellent durability, reliable adhesion to the concrete surface, and reinforcement by wrapping the area to be reinforced and reinforced.

However, the reinforcing method using the carbon fiber sheet has to go through a cumbersome and complicated manual process as described above, and if the number of laminated sheets is increased to increase the reinforcing effect, the reinforcing effect according to the number of laminated sheets is not proportional, and the process time is long and uniform. There is a problem in dimensional safety because it is difficult to construct with a lamination width.

In addition, the effect of reinforcing is that the effect is exhibited only when the above-described carbon fiber sheet is attached over a wide range. In this case, there is a problem in that there is no breathability, and the construction cost increases according to the amount of material to be provided.

Next, there is a method of producing prestressed concrete by prestressing the concrete structure during construction.

Here, as a method for prestressing the concrete structure, when the PS steel wire is tensioned and installed before pouring concrete, it is called a pretension method, and the method of tensioning the PS steel wire after the concrete is cured is called a post tension method.

(Patent Document 1) KR10-0537407 B1 Reinforcing material Reinforcement method of vertically inserted structure

(Patent Document 2) KR10-1255471 B1 Prestressed tension material with free orientation and tension member fixing structure of atypical concrete structure using the same

However, in the method using the above-mentioned reinforcing material, the use of reinforcing material having a material characteristic similar to that of the most commonly used reinforcing material is most advantageous in terms of design properties, but fiber reinforcement materials such as carbon fiber have very strong reinforcing bars and their mechanical properties. Because it is different, it has difficulties in reinforcement design and is not economical. The method of simply attaching a steel plate with similar material properties to reinforcing bars using an anchor increases the weight of the steel plate as well as the damage to the matrix, so the reinforcement performance against weight is very inefficient. The method of manufacturing the prestressed concrete structure to solve this problem could solve the problem of increasing the reinforcement efficiency compared to the weight of the reinforcement material, but a separate mechanical device is required for attaching to the concrete or combining with the entire structure. And, there was a problem that the production process was complicated and the production time was long.

In addition, many of the existing structures are underground structures, and most of them take the form of indeterminate structures. Reinforcement in such structures may be difficult to reinforce with existing reinforcement methods, or may result in economic loss by remodeling the structure altogether.

In order to solve the above problems, the cracking, deformation recovery and load bearing reinforcing method of the existing reinforcing concrete structure using the recoverability characteristics of the iron-based reinforcing alloy according to the present invention is a reinforcing material that has the most used reinforcing bars and mechanical properties. Similar to Fe-Mn-Si-based shape memory alloys, Ti and excessively dispersed C are precipitated through a precipitation hardening heat treatment to precipitate fine Ti-C precipitation phases. The phosphorus yield strength is increased, but the Fe-Mn-Si-based shape memory alloy contains Ti and excessively dispersed C at the same time, and the content of C is relatively increased while the content of Cr is lowered, but the weight ratio of Ti and C is adjusted. By forming the Ti-C precipitation phase smoothly, chromium carbide (Cr23C6) precipitates are not formed, and the iron-based memory alloy with improved mechanical properties is manufactured to increase work efficiency and to reduce productivity and cost. The purpose is to provide a method of reinforcing the cracking, deformation recovery, and load carrying capacity of existing reinforced concrete structures using the recoverability characteristics of the iron-based memory alloy.

Another object of the present invention is to reinforce the existing concrete structure by using an iron-based reinforcing material reinforced with an iron-based reinforcing alloy pre-deformed, and then partially or modified by heating the iron-based reinforcing material with a contact or non-contact electric induction coil. It is intended to improve the cracking, deformation recovery and load carrying capacity of existing concrete structures by controlling the cracks and deformations occurring in the existing concrete structures by restoring the whole and adding the prestressing force.

Another object of the present invention is to improve the axial force, shear force, bending moment, torsional moment resistance, increase ductility, and seismic performance of concrete by introducing an iron-based memory alloy reinforcement, thereby reducing the cross-sectional area during reinforcement design, reducing cost and reducing work time , In order to induce space utilization and weight reduction of structures.

Another object of the present invention is to improve the existing concrete structure without using a complicated mechanical device using a contact type or non-contact type electric induction coil to provide a recovery stress to the iron-based suppository reinforcement material, thus shortening the working time and reducing transportation problems and It is intended to reduce economic losses by preventing discontinuation.

Another object of the present invention is to re-tension by activating the recovery stress of the iron-based reinforcing alloy reinforcement by heating with a contact or non-contact electric induction coil when deformation occurs during use after reinforcement by reviewing the degree of recovery stress in advance in the existing concrete structure. It is to help you get the effect.

Another object of the present invention is to enable reinforcement even in situations in which reinforcement is difficult with existing reinforcement methods such as underground structures or irregular structures.

The present invention is a Fe-Mn-Si-based shape memory alloy having similar mechanical properties to rebars most frequently used in concrete structures as reinforcing materials, and precipitates fine Ti-C precipitates through precipitation hardening heat treatment of C and Ti dispersed in excess. The recovery stress is improved and the yield strength, which is the mechanical strength, is increased without separate training of the shape memory alloy, but Ti and excessively dispersed C are simultaneously included in the Fe-Mn-Si type shape memory alloy, and the content of Cr is lowered. While the content of C is relatively high, Ti-C precipitation phase is smoothly formed by adjusting the weight ratio of Ti and C to prevent the formation of chromium carbide (Cr23C6) precipitates, and the work is made by manufacturing an iron-type memory alloy with improved mechanical properties. In addition to increasing efficiency, productivity and cost reduction effects can be obtained.

In addition, after reinforcing the existing concrete structure using the iron-based reinforcing material reinforced with the iron-based reinforcing alloy pre-deformed, the iron-based reinforcing material is heated with a contact-type or non-contact electric induction coil to recover some or all of the deformed material, and prestressing. By applying a force, it is possible to control the cracks and deformations occurring in the existing concrete structures to improve the cracks, deformation recovery and load carrying capacity of the existing concrete structures.

In addition, by introducing the iron-based reinforcing material reinforcement material, the axial force, shear force, bending moment, torsional moment resistance, and increase in ductility and seismic performance of concrete can be reduced to reduce the cross-sectional area during reinforcement design, thereby reducing cost, reducing work time, reducing space utilization, and structure It can induce lighter weight.

In addition, when reinforcing the existing concrete structure, the working time is shortened and traffic problems and stoppage are prevented because the recovery stress is applied to the iron-based stiffener alloy reinforcement by heating with a contact or non-contact electric induction coil without using a complicated mechanical device. By doing so, economic losses can be reduced.

In addition, if the deformation occurs during use after reinforcement by reviewing the degree of recovery stress in the existing concrete structure in advance, it is possible to obtain a retension effect by activating the recovery stress of the iron-based reinforcing alloy reinforcement by heating with a contact or non-contact electric induction coil.

In addition, it is a useful invention that can be reinforced even in situations where reinforcement is difficult with existing reinforcement methods, such as underground structures or irregular structures.

1 is a block diagram showing a method of manufacturing an iron-based memory alloy in the present invention.
Figure 2 is a photograph showing a tester for the U-bending test of the iron-based memory alloy.
Figure 3 is a photograph showing the state of measuring the vertical displacement of the sample after the U-bending test.
Figure 4 is a photograph showing the results of the U-bending test before and after the heating of the iron-based memory alloy.
Figure 5 is a diagram showing the results of the shape recovery test of the iron-based memory alloy.
Figure 6 (a) is a front view showing the bending reinforcement state of the beam or slab is not good adhesion strength using the iron-based memory alloy reinforcement in the present invention, Figure 6 (b) is a side view.
Figure 7 (a) is a front view showing the bending reinforcement state of the beam or slab with good adhesion strength using the iron-based memory alloy reinforcement in the present invention, Figure 7 (b) is a side view.
Figure 8 (a) is a front view showing the shear reinforcement state of the beam or slab using the iron-based reinforcing material reinforcement in the present invention, Figure 8 (b) is a side view.
Figure 9 is a front view showing the reinforcement state of the pillar using the iron-based reinforcing material reinforcement in the present invention.
Figure 10 is a front view showing the shear reinforcement state of the culvert using the iron-based stiffener alloy reinforcement in the present invention.
11 is a plan view showing a reinforcement state of a structure in which an opening is formed using the iron-based memory alloy reinforcement of the present invention.
12 is a plan view showing a reinforcement state of a crack-formed structure using a staple-type iron-based reinforcing alloy reinforcement in the form of a stapler in the present invention.
13 is a state diagram showing a state of applying heat to the iron-based reinforcing material reinforcement in the present invention.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

end. Steel-type memory alloy reinforcement manufacturing step

This step is a process for manufacturing a reinforcing material 20 made of an iron-based memory alloy.

Here, the iron-based spheroidal alloy in this step is Mn 14 ~ 19wt%, Si 3 ~ 7wt%, Cr 4.5 ~ 5.5wt%, Ti 0.1 ~ 2wt%, C 0.05 ~ 0.3wt%, Ni 3.5 ~ 4.5wt% and The balance includes Fe, but is formed by depositing a Ti-C precipitated phase through a precipitation hardening heat treatment. At this time, Ti and C constituting the Ti-C precipitated phase have a weight ratio of 3.8 to 4.2: 1.

To this end, in the present invention, an iron-based memory alloy is manufactured.

The iron-based memory alloy includes Mn 14 ∼ 19 wt%, Si 3 ∼ 7 wt%, Cr 4.5 ∼ 5.5 wt%, Ti 0.1 ∼ 2 wt%, C 0.05 ∼ 0.3 wt%, Ni 3.5 ∼ 4.5 wt% and the balance Fe. , It is formed by depositing a Ti-C precipitated phase through a precipitation hardening heat treatment. At this time, Ti and C constituting the Ti-C precipitated phase have a weight ratio of 3.8 to 4.2: 1.

This, iron-based storage alloy includes Mn 14 to 19wt%, Si 3 to 7wt%, Cr 4.5 to 5.5wt%, Ti 0.1 to 2wt%, C 0.05 to 0.3wt%, Ni 3.5 to 4.5wt% and balance Fe After preparing the ingot, and hot rolling the ingot to prepare a primary iron-based memory alloy, the primary iron-based memory alloy is subjected to precipitation hardening heat treatment at a temperature of 700 to 1,000 ° C to precipitate Ti-C. Precipitation of the phase makes it possible to manufacture.

Here, when the C is mixed below the threshold, it is difficult to expect mechanical properties, and when it exceeds the threshold, mechanical strength is improved, but it is difficult to work in various shapes, and mass production is difficult, which limits restrictions on commercial applications. Will receive.

In addition, Ti has higher reactivity with C than Cr, so it reacts preferentially with C, so even if a large amount of C is added, coarse chromium carbide (Cr23C6) precipitates having a significant adverse effect on the strength of the material are not exhibited.

These Ti and C are made of a weight ratio of 3.8 to 4.2: 1, and when it is less than the threshold, it is difficult to expect high mechanical strength yield strength and shape recovery strength, and when it exceeds the threshold, the content ratio of other compositions is changed. There is no

The iron-based precipitating alloy containing the Ti-C precipitated phase as described above precipitates fine Ti-C precipitated phase through precipitation hardening heat treatment of Ti and excessively dispersed C in a Fe-Mn-Si-based shape memory alloy to recover the recovery stress. In addition to the improvement, it is possible to simultaneously improve the yield strength, which is the mechanical strength, and in particular, Ti and excessively dispersed C are simultaneously included in the Fe-Mn-Si-based shape memory alloy, and the content of C is relatively reduced while the content of Cr is lowered. By increasing the weight ratio of Ti and C, Ti-C precipitates are smoothly formed, thereby preventing the formation of chromium carbide (Cr23C6) precipitates, thereby improving mechanical properties.

Looking at the embodiment of the shape memory alloy as described above in more detail as follows.

[Example]

end. Stage 1

In order to carry out this step, as shown in Table 1 below, an ingot of an iron-based memory alloy made of various components was prepared.

Alloy composition table for each sample to be used in the experiment sample Furtherance Mother alloy (g)
(Fe-17Mn-5Si-5Cr) Additional elements sum
(g) Ni (g) C (g) Ti (g) One Fe-17Mn-5si-5Cr 250 250.0 2 Fe-17Mn-5si-5Cr-1Ni 250 2.5 252.5 3 Fe-17Mn-5si-5Cr-4Ni 250 10 260.0 4 Fe-17Mn-5si-5Cr-4Ni-0.05c 250 10 2.6 262.6 5 Fe-17Mn-5si-5Cr-4Ni-0.1C 250 10 5.2 265.2 6 Fe-17Mn-5si-5Cr-4Ni-0.3C-1Ti 250 10 15.6 2.5 278.1

(C used a partial alloy (Fe-4.8% C alloy)) As shown in Table 1 above, samples 1 to 6 were dissolved for each composition to prepare a bar-shaped incoat.

I. Stage 2

Each ingot in the first step was subjected to a homogenization heat treatment at 1,100 ° C. for 24 hours, followed by hot rolling at ingot for 1 hour at 1,000 ° C., and hot rolling at 1,000 ° C. for 5 minutes at a stepwise thickness of 6 mm. After the final hot rolling was completed, it was cooled by a water-cooling method to prepare a first iron-based memory alloy of Samples 1 to 6.

Everything . Stage 3

In order to precipitate the Ti-C precipitation phase from the first iron-based memory alloy produced in the second step, the temperature was performed for 2 hours at a temperature of 800 ° C., after which a flattening operation was performed to finally obtain the iron-based memory of Samples 1 to 6 Alloys were prepared.

[Experiment 1]: U-bending test

As shown in Fig. 2, samples 1 to 6 in the form of strips having a thickness of 0.7 mm and a width of 3 mm were prepared, and samples 6 to 6 were bent in a U-shape using a tool having a diameter of 20 mm in order to examine the shape restoration characteristics of a number of samples. At this time, samples 1 to 6 bent up to the maximum bending point (strain rate of 4%) were placed in an oven preheated to 100 ° C, 150 ° C, and 200 ° C for 2 hours, and then cooled, and then restored again. The results are as shown in FIG. 4.

Here, batches 1 to 6 in Fig. 4 mean samples 1 to 6.

As shown in FIG. 4, it can be seen that the shape restoration occurs from a temperature of 150 ° C., and in particular, it can be seen that the amount of shape restoration of the sample 5 containing the additional element C and the sample 6 containing the additional element C and Ti is significantly improved. .

[Experiment 2]: Uni-axial tensile test

In this test, samples 1 to 6 were measured using a uniaxial tensile tester.However, in the case of sample 1, the value of the yield strength, which is a mechanical property during the experiment, was too low to perform the experiment. As in, σy in Figure 5 means the yield strength.

As shown in FIG. 5, samples with the highest yield strength (σy) were samples 2 and 3, and samples with the highest yield strength (σy) were sample 6.

In general, in order to obtain a high recovery stress, it is ideal to show a shape recovery force of a certain level or higher while the yield strength of a material is high, but in general alloy design, the shape recovery force rapidly decreases when the yield strength increases, but the present invention is adjusted through heat treatment. When the Ti-C precipitation phase is dispersed, it is possible to form a considerable level of shape recovery while increasing the yield strength.

In particular, as can be seen from the experimental results, in the case of the sample 6 containing Ti, the yield strength of the material of about 0.2% is higher than that of the sample 5 without Ti, and the result of not significantly decreasing with the sample 5 even in the shape recovery force. This is because Ti produced a Ti-C precipitated phase that reacts with C to improve mechanical strength while increasing shape recovery.

As confirmed through the above examples and experiments, the iron-based memory alloy in the present invention can obtain sufficient strength without a separate training process, and in particular, it can be restored to its original state by applying a heat source after tensile deformation.

Thereafter, an iron-based alloy reinforcement material 20 made of an iron-based shape-reducing alloy in which the length is forcibly deformed by applying an external force to the iron-type relieving alloy is manufactured.

Here, when manufacturing the iron-based alloy reinforcing material 20 using the iron-based memory alloy, the shape may be manufactured in any one of a circular shape, a release shape, a plate shape, a hollow shape, and a stapling shape.

I. Stage of rearranging the base surface of the existing concrete structure

This step is a step of arranging the surface of the existing concrete structure 10 that is deformed by overload during use and needs reinforcement.

In other words, the removal of foreign substances from the surface of the existing concrete structure 10 may be performed, and in some cases, a flat operation and a cleaning operation may be performed to clean up so that a healthy ground surface can be formed to complete this step.

All. Iron-based memory alloy reinforcement attachment step

This step is a step of attaching the iron-based spheroidal alloy reinforcement 20 to the cleaned surface of the existing concrete structure 10 through the rearranging step of the base surface of the existing concrete structure.

Here, the above-described existing concrete structure 10 may be in the form of a beam or a slab, a column, or a column, as shown in FIGS. 6 to 11, or may be in the form of a structure in which an opening 14 in a vertical direction is formed. In order to fix the iron-based memory alloy reinforcement 20, an anchor bolt 30 may be additionally used, or a fiber reinforced mortar 40 may be further applied to complete this step.

The present invention can be attached to the iron-based memory alloy reinforcement 20 in a variety of ways depending on the structure and condition of the existing concrete structure (10).

For example, as shown in FIG. 6, when the existing concrete structure 10 is a beam or a slab having poor adhesion, the anchor bolt 30 is used after placing the iron-based memory alloy reinforcement 20 on the ground surface. Both ends can be fixed.

At this time, the first support of the iron-based memory alloy reinforcement 20 supports the iron-based memory alloy reinforcement 10 by supporting a support (not shown in the drawing), and then uses the anchor bolt 30 to anchor the iron-based memory reinforcement. When the process of fixing both ends of (20) to the existing concrete structure (10) is completed, the iron-based memory alloy reinforcement (20) can be fixed by removing the support (not shown).

In addition, in the present invention, in the state in which the fixing of the iron-based memory alloy reinforcement 20 to the existing concrete structure 10 is completed as described above, the iron-based memory storage reinforcement 20 and the iron-based memory alloy reinforcement 20 are fixed. The fiber-reinforced mortar 40 may be applied to the attachment surface of the concrete structure 10 by hand or by using shotcrete.

Here, the above-described fiber-reinforced mortar 40 is coated on the surface of the iron-based reinforcing material reinforcement 20 to prevent corrosion of the iron-based reinforcing material reinforcement 20 while prestressing effect through adhesion with the iron-based reinforcing material reinforcement 20 It is included to help you get.

In addition, as shown in FIG. 7, when the existing concrete structure 10 is a beam or slab having good concrete adhesion strength, the concrete groove 13 is formed in the existing concrete structure 10 and then the concrete groove 13 ) Can be reinforced by combining the iron-based memory alloy reinforcing material 20, and by applying the grout material 60 to the attachment surface of the existing concrete structure 10 to which the iron-based memory alloy reinforcing material 20 is combined, the iron-based shape The memory alloy reinforcement 20 can be fixed to the existing concrete structure 10.

And when shear reinforcement in the case where the existing concrete structure 20 is a beam or a slab as shown in FIG. 8, the iron-type spheroidal alloy reinforcement 20 is manufactured in a U-shape as shown in FIG. 8, and then the existing concrete structure 10 After placing the side and both sides of the form in the form can be combined using the anchor bolt (30).

Here, when shear reinforcement of a beam or a slab, the U-shaped iron-based memory alloy reinforcing material 20 and the iron-based memory alloy reinforcing material 20 in the form of a plate can be used together, in particular, the existing concrete structure 10 In view of the fact that the crack of the diagonal occurs in the form of a plate-shaped iron-based memory alloy reinforcing material 20 may be attached to the existing concrete structure 10 at an angle perpendicular to the slope where the crack occurred.

In addition, as shown in FIG. 9, in the case of reinforcement in the case of a pillar that is the existing concrete structure 10, the iron-based spheroidal alloy reinforcement 20 may be reinforced by combining it with the existing concrete structure 10 in the form of a spiral rebar.

Particularly, when the iron-based memory alloy reinforcing material 20 is spirally coupled when reinforcing the existing concrete structure 10 in the form of a column as described above, epoxy (not shown in the drawings) is attached to the attachment surface to which the iron-based memory alloy reinforcing material 20 is attached. ) Is applied to temporarily attach the iron-based memory alloy reinforcing material 20 and then the anchor bolts 30 are coupled to both ends of the iron-based memory alloy reinforcing material 20 to complete fixing.

And as shown in Figure 10, when the existing concrete structure 10 is sheared reinforcement in the case of a culvert form, it is not shown in the drawing, but after forming the concrete groove 13 as in Figure 2, the iron groove shape in the concrete groove 13 Reinforcement can be carried out by inserting the memory alloy reinforcement 20, in which case the iron-based memory alloy reinforcement 20 takes into account that the vertical, horizontal direction and cracks of the existing concrete structure 10 occur diagonally. The iron-based reinforcing alloy reinforcement 20 in the form of a plate may be attached to the existing concrete structure 10 at an angle perpendicular to the slope where the crack occurred.

Moreover, although not shown in FIG. 10, the fiber-reinforced mortar may be applied after the iron-based reinforcing material reinforcement 20 is attached.

In addition, when the existing concrete structure 10 is a structure in the form of forming the opening 14 in the vertical direction, when reinforcing the concrete as shown in FIG. 7 around the opening 14 for the reinforcement of the opening 14 The groove 13 is formed in a direction perpendicular to the line connecting the corners of the opening in a diagonal direction, and the iron-based memory alloy reinforcement 20 can be coupled to the concrete groove 13, and at this time, the iron-based memory alloy In order to prevent the reinforcing material 20 from falling off, the fiber-reinforced mortar 40 may be further applied by hand or by using shotcrete to be constructed.

In addition, the reinforcement in the case of the existing concrete structure 10 in which the crack 15 has occurred is an angle at a right angle to the slope in which the crack 15 has occurred, in the stapling-type iron-based memory alloy reinforcement 20 as shown in FIG. 13. It can be attached to the existing concrete structure (10).

la. Construction completion stage

This step is a step for completing the construction by applying the prestressing force to the existing concrete structure 10 by heating the iron-based memory alloy reinforcement 20 attached to the existing concrete structure 10.

For this step, in the present invention, a contact-type or non-contact type electric induction coil 50 may be used as a means for heating the iron-based memory alloy reinforcement 20.

The contact-type or non-contact type electric induction coil 50 is a portable and convenient to move, and a heat source is applied without directly contacting the iron-based reinforcing material 20, and the fiber-reinforced mortar 40 is applied as shown in FIG. It can transfer heat source even in the state of being.

At this time, in the present invention, it is possible to control the recovery stress by changing heating conditions such as heating time or heating temperature.

Particularly, a hollow iron-based memory alloy reinforcement 20 is used for the existing concrete structure 10 in which the thickness of the fiber-reinforced mortar 40 is thick or the contact or non-contact electric induction coil 50 is insufficient to transfer heat sources.

Thereafter, although not shown in detail in the drawings, the nichrome wire is inserted into the hollow shape of the iron-based suppository alloy reinforcement 20 in a U-shape to construct both ends to be exposed to the outside, and then contact or non-contact electric induction coil 50 After the heat source transfer operation through), this step can be completed by additionally generating a heat source by electrical resistance by applying power to the nichrome wire at a position where heat transfer is insufficient with only the contact or non-contact electric induction coil 50.

Deformation recovery method of the existing concrete structure 10 through the above-described method is the iron-based precipitating alloy containing a Ti-C precipitation phase, precipitation hardening of Ti and excessively dispersed C in a Fe-Mn-Si-based shape memory alloy Through the precipitation of fine Ti-C precipitates, the recovery stress can be improved and the yield strength, which is mechanical strength, can be simultaneously improved. In particular, Ti and excessively dispersed C are simultaneously included in the Fe-Mn-Si-based shape memory alloy. In addition, while lowering the Cr content, the C content is relatively high, but the Ti-C precipitation phase is smoothly formed by adjusting the weight ratio of Ti and C to prevent the formation of chromium carbide (Cr23C6) precipitates, thereby improving mechanical properties. Thereby, the manufacturing process is simplified to increase the work efficiency, and of course, the productivity is increased, thereby reducing the cost.

In addition, since the iron-based reinforcing material reinforcement 20 manufactured by pre-deforming the iron-based reinforcing alloy as described above activates a recovery stress by a heat source of the electric induction coil 50, it forms a prestressing force itself. When reinforcing the existing concrete structure 10, after including the iron-based memory alloy reinforcement 20, after heating the iron-based memory alloy reinforcement 20 with an electric induction coil 50 to activate the recovery stress, the concrete 11 is actively activated Applying compressive force to the axial force, shearing force, bending moment, torsional moment of the concrete 11 to improve resistance, improve ductility and seismic performance, and control cracks or deformations occurring in the existing concrete structure 10 to control cracks and deformations. It can be prevented.

Moreover, by improving the axial force, shear force, and torsional moment of the concrete 11 as described above, and improving the ductility and seismic performance, it is possible to form sufficient strength even if the design is reduced by reducing the cross-sectional area during the reinforcement design of the existing concrete structure 10 Accordingly, it is possible to obtain an effect capable of inducing weight reduction of the existing concrete structure 10 due to cost reduction, space utilization due to reduction in cross-section, and reduction in cross-section.

In particular, the temperature and time of the contact or non-contact electric induction coil 50 depending on the importance of the structure when activating the recovery stress by applying heat to the existing concrete structure 10 with the above-described contact or non-contact electric induction coil 50 By changing the heating conditions as described above, the magnitude of the recovery stress can be controlled to adjust the prestressing force acting on the structure.

In addition, the recovery method according to the present invention is a contact or non-contact electric induction coil (50) even if the deformation of the existing concrete structure 10 occurs again due to an overload during use after the existing concrete structure 10 is recovered by the recovery method. ) Can be used to restore the existing concrete structure (10).

In addition, since the present invention activates the recovery stress on the iron-based reinforcing material reinforcement 20 using an electric induction coil 50 without a complicated mechanical device, the working time is shortened to prevent traffic problems and stoppages, thereby reducing economic loss. Can be reduced.

Moreover, when deformation occurs during use after construction of the existing concrete structure 10, it is heated with a contact type or non-contact type electric induction coil 50, thereby activating a recovery stress on the iron-based stiffener alloy reinforcement 50, thereby preventing the irregularities of FIGS. 5 to 6 It is also possible to obtain an effect that can be reinforced even in situations where reinforcement is difficult, such as a regular structure.

Although the above-described embodiment is described for the most preferred example of the present invention, it is not limited to the above-described embodiment, and various modifications are possible without departing from the technical spirit of the present invention. It is obvious to the engineers.

10: existing concrete structure
DESCRIPTION OF SYMBOLS 11 Concrete 12 Reinforcing material 13 Concrete groove 14 Opening 15 Crack
20: iron-based memory alloy reinforcement
30: anchor bolt
40: fiber reinforced mortar
50: electric induction coil
60: grout material

Claims (8)

An iron-based memory alloy reinforcing material fabrication step of producing a reinforcing material made of the iron-based memory alloy that is deformed by forcibly increasing the length of the iron-based memory alloy that is restored to its original state by a heat source after tensile deformation;
An existing concrete structure foundation cleanup step of arranging the surface of the existing concrete structure made of any one of a beam or slab to be reinforced, a column, and a structure in which vertical openings are formed;
Attaching an iron-based memory alloy reinforcing material to the existing concrete structure;
Construction completion step of completing the reinforcement by adjusting the size of the recovery stress by changing the heating conditions of the contact-type or non-contacting electric coil of the iron-based memory alloy reinforcing material attached to the existing concrete structure and applying the prestressing force to the existing concrete structure. Including, but,
In the manufacturing step of the iron-type alloy reinforcement, the iron-based memory alloy is Mn 14 ∼ 19 wt%, Si 3 ∼ 7 wt%, Cr 4.5 ∼ 5.5 wt%, Ti 0.1 ∼ 2 wt%, C 0.05 ∼ 0.3 wt%, Ni 3.5 ∼ 4.5 After preparing an ingot containing wt% and the balance Fe, and hot rolling the ingot to prepare a primary iron-based memory alloy, the primary iron-based memory alloy is precipitate hardened at a temperature of 700 to 1,000 ° C. Proceed to precipitate the Ti-C precipitation phase,
Ti and C constituting the Ti-C precipitation phase is made of a weight ratio of 3.8 to 4.2: 1, and prevents chromium carbide (Cr23C6) precipitates from appearing.
In the manufacturing step of the iron-based memory alloy reinforcing material, the iron-based memory alloy is made of any one selected from among circular, molded, plate-shaped, hollow, and stapled shapes,
In the case of shear reinforcement of a beam or slab in the step of attaching the iron-based reinforcing alloy reinforcement, the iron-based reinforcing alloy reinforcing material is manufactured in a U-shape, placed on both sides of the existing concrete structure, and then combined using anchor bolts. However, the U-shaped iron-based spheroidal alloy reinforcement is used together with the iron-based spheroidal alloy reinforcement in the form of a plate. Attached to, and after the adhesion of the reinforcing metal alloy reinforcing material, the method of cracking, deforming and reloading the existing reinforcing concrete structure using the recovery ability characteristics of the iron reinforcing metal alloy characterized by further applying a fiber-reinforced mortar.
delete delete delete delete An iron-based memory alloy reinforcing material fabrication step of producing a reinforcing material made of the iron-based memory alloy that is deformed by forcibly increasing the length of the iron-based memory alloy that is restored to its original state by a heat source after tensile deformation;
An existing concrete structure foundation cleanup step of arranging the surface of the existing concrete structure made of any one of a beam or slab to be reinforced, a column, and a structure in which vertical openings are formed;
Attaching an iron-based memory alloy reinforcing material to the existing concrete structure;
Construction completion step of completing the reinforcement by adjusting the size of the recovery stress by changing the heating conditions of the contact-type or non-contacting electric coil of the iron-based memory alloy reinforcing material attached to the existing concrete structure and applying the prestressing force to the existing concrete structure. Including, but,
In the manufacturing step of the iron-type alloy reinforcement, the iron-based memory alloy is Mn 14 ∼ 19 wt%, Si 3 ∼ 7 wt%, Cr 4.5 ∼ 5.5 wt%, Ti 0.1 ∼ 2 wt%, C 0.05 ∼ 0.3 wt%, Ni 3.5 ∼ 4.5 After preparing an ingot containing wt% and the balance Fe, and hot rolling the ingot to prepare a primary iron-based memory alloy, the primary iron-based memory alloy is precipitate hardened at a temperature of 700 to 1,000 ° C. Proceed to precipitate the Ti-C precipitation phase,
Ti and C constituting the Ti-C precipitation phase is made of a weight ratio of 3.8 to 4.2: 1, and prevents chromium carbide (Cr23C6) precipitates from appearing.
In the manufacturing step of the iron-based memory alloy reinforcing material, the iron-based memory alloy is made of any one selected from among circular, molded, plate-shaped, hollow, and stapled shapes,
When shear reinforcement when the existing concrete structure is in the form of a culvert in the step of attaching the iron-based reinforcing material to the reinforcing alloy, the steel-type reinforcing alloy reinforcing material is inserted into the concrete groove and reinforced. Iron-based shape characterized by attaching the iron-based reinforcing material reinforcement in the horizontal direction and plate form to the existing concrete structure at an angle perpendicular to the slope where the crack occurred, and further applying fiber-reinforced mortar after the iron-based reinforcing material reinforcement is attached. Cracking, deformation recovery and load-bearing reinforcement method of existing reinforced concrete structures using memory alloy's recovery ability characteristics.
An iron-based memory alloy reinforcing material fabrication step of producing a reinforcing material made of the iron-based memory alloy that is deformed by forcibly increasing the length of the iron-based memory alloy that is restored to its original state by a heat source after tensile deformation;
An existing concrete structure foundation cleanup step of arranging the surface of the existing concrete structure made of any one of a beam or slab to be reinforced, a column, and a structure in which vertical openings are formed;
Attaching an iron-based memory alloy reinforcing material to the existing concrete structure;
Construction completion step of completing the reinforcement by adjusting the size of the recovery stress by changing the heating conditions of the contact-type or non-contacting electric coil of the iron-based memory alloy reinforcing material attached to the existing concrete structure and applying the prestressing force to the existing concrete structure. Including, but,
In the manufacturing step of the iron-type alloy reinforcement, the iron-based memory alloy is Mn 14 ∼ 19 wt%, Si 3 ∼ 7 wt%, Cr 4.5 ∼ 5.5 wt%, Ti 0.1 ∼ 2 wt%, C 0.05 ∼ 0.3 wt%, Ni 3.5 ∼ 4.5 After preparing an ingot containing wt% and the balance Fe, and hot rolling the ingot to prepare a primary iron-based memory alloy, the primary iron-based memory alloy is precipitate hardened at a temperature of 700 to 1,000 ° C. Proceed to precipitate the Ti-C precipitation phase,
Ti and C constituting the Ti-C precipitation phase is made of a weight ratio of 3.8 to 4.2: 1, and prevents chromium carbide (Cr23C6) precipitates from appearing.
In the manufacturing step of the iron-based memory alloy reinforcing material, the iron-based memory alloy is made of any one selected from among circular, release, plate, hollow, and staple types.
When the existing concrete structure is forming an opening in the vertical direction in the step of attaching the iron-based memory alloy reinforcement, a concrete groove is formed in a direction perpendicular to a line connecting the edges of the opening diagonally around the opening, and the concrete groove To the iron-based reinforcing material reinforcement material, and after attaching the iron-based reinforcing material reinforcement material, the fiber-reinforced mortar is further applied to crack, deform and recover loads of the existing reinforcing concrete structure using the recoverability characteristics Reinforcement method.
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