KR102174923B1 - Structure for preventing non shrinkage mortar crack of bridge bearing - Google Patents

Abstract

The present invention relates to a structure for preventing non-shrinkage mortar cracks of a bridge seat device, which can control the cracks caused by stress concentration at each corner of a lower plate of the bridge seat device mounted on a bridge seat part made of a non-shrinkage mortar mat. To this end, the structure for preventing non-shrinkage mortar cracks of a bridge seat device includes a crack preventing device having a binding part helping fastening with anchors arranged on lower surfaces of each corner of the lower plate and a crack preventing part coupled to the binding part to be movable forward and/or backward and helping stress dispersion, wherein the crack preventing device has the arc-shaped crack preventing plate arranged to be embedded in the non-shrinkage mortar mat so as to surround surroundings of each corner of the lower plate.

Description

Structure for preventing non shrinkage mortar crack of bridge bearing}

The present invention relates to a non-shrink mortar crack prevention structure of an abutment device, and in particular, to prevent a crack that may occur in a cement mortar (or concrete) that is hardened to fix the position of the abutment device installed between a support object and an installation object, and/or It relates to a structure for restraining abutment device.

In general, in structures such as bridges, a bridge seating device is employed in order to increase the durability life of the structure while securing the stability of the structure.

For example, the bridge seating device is interposed at the junction of the upper structure of the bridge and the pier supporting its load, and can accommodate the vertical load acting on the upper structure and the displacement due to impact such as temperature change, wind power, and earthquake. In addition, the upper structure can be supported on the basis of the lower structure, thereby providing the function of promoting the safety of the structure.

As widely known to those skilled in the art, the bridge seating device for a bridge is mounted on a bridge seat made of a concrete mat that is hardened by placing a base plate on the upper part of the pier, installing a form around the bridge seating device, and pouring a non-shrink mortar. For example, in such a structure, the volume of concrete changes due to exposure to environments such as temperature change and drying shrinkage, and stress is generated in response to the changed volume. The stress is concentrated at the boundary edge 120a between the base plate 120 and the concrete mat 21, and causes a fracture pattern of the concrete due to the stress concentration (see FIG. 8). Concrete cracking (or breakage) continuously expands the extent of the crack and has a great influence on the stability of the concrete structure.

When cracks and breakages of the bridge seat made of a concrete mat occur, the concrete of the bridge seat must be demolished and a new bridge seat must be constructed or the cracked area must be repaired as disclosed in Patent Document 1.

Korean Patent Publication No. 10-0403158

The present invention has been created in order to solve the above-described problems, and an object of the present invention is to provide a structure for preventing concrete cracking at each corner portion of the lower plate in contact with the non-shrink mortar mat.

In order to achieve the above object, the present invention,

In the abutment device for attaching the lower plate to the top of the installation object, including a lower plate with an anchor on the lower surface of each corner, and the anchor of the lower plate is embedded and installed in the non-shrink mortar mat,

A coupling portion having a coupling ring fastened to the outer circumferential surface of the anchor, and a coupling extension pipe extending in the outer direction from the coupling ring; It may include a crack prevention device consisting of; a crack prevention plate curved in an arc shape for stress distribution, and a crack prevention part having a fastening protrusion extending in length from the inner circumferential surface of the crack prevention plate and inserted into the fastening extension pipe. Here, the crack prevention tool may control cracks occurring in the cured non-shrink mortar mat around each corner of the lower plate by arranging the crack prevention plate to be embedded in the non-shrink mortar mat so as to surround each corner of the lower plate. .

Preferably, the crack prevention tool of the present invention may be configured to enable reciprocating movement of the crack prevention part in the fastening extension pipe of the binding part.

Specifically, the fastening extension pipe may have a female thread formed on the inner circumferential surface of the inner hollow, and the fastening protrusion may be formed with a male thread on the outer circumferential surface so as to be screwed with the fastening extension tube.

The crack prevention part of the present invention arranges the outer circumferential surface of the crack prevention plate to be inclined upward at the end of the fastening protrusion, and the crack prevention plate is 0° to 60°, preferably 45°, based on a virtual vertical line at the end of the fastening projection. Can be placed in an upward slope.

Optionally, the crack prevention plate may further include a protrusion for inducing stress concentration in a triangular cross-sectional shape extending in a vertical direction from the center of the outer peripheral surface.

Optionally, the crack prevention plate may further arrange an uneven shape plate at the center of the crack prevention plate.

In an embodiment of the present invention, the seating device is installed between the support object and the installation object, an upper plate installed under the support object, a lower plate fixed to an upper portion of the installation object so as to face the upper plate, and an upper plate. It is installed between the lower plates and may be composed of a support member for receiving the displacement of the upper plate while supporting the upper plate.

Features and advantages of the present invention will become more apparent from the following detailed description based on the accompanying drawings.

Prior to this, terms or words used in the present specification and claims should not be interpreted in a conventional and dictionary meaning, and the inventor may appropriately define the concept of the term in order to describe his or her invention in the best way. It should be interpreted as a meaning and concept consistent with the technical idea of the present invention based on the principle that there is.

According to the above description of the present invention, the present invention is provided to prevent cracks that may occur around the edge of the lower plate of the seating device, specifically at the boundary between the edge of the lower plate and the non-shrink mortar mat.

The present invention is concentrated in the corner by embedding and installing a simple structured crack prevention hole in the non-shrinkable mortar that is supplied and placed between the lower plate and the top of the installation object (pier) to form the abutment on the bottom of the lower plate of the abutment device. Dispersing the stress can control the spread or growth of the shrinkage mortar crack. Through this, the present invention can improve the durability of the bridge by preventing cracks in the non-shrinkable mortar mat that is ultimately hardened by pouring the non-shrinkable mortar.

In addition, the present invention is configured to be easily fastened to the anchor of the bridge seating device, as well as to adjust the separation distance between the crack prevention plate and the coupling ring according to the construction site.

1 is an exploded perspective view as viewed from above of an embodiment of a non-shrink mortar crack prevention structure of a seating device according to the present invention.
2 is a perspective view of an embodiment of the non-shrinkable mortar crack prevention structure of the seating device according to the present invention as viewed from below.
3 is a partial cutaway view of the crack prevention tool shown in FIG. 1.
Figure 4 is a state diagram of the use of the shrinkage mortar crack prevention structure of the seating device according to the present invention.
5 is a distribution diagram of a crack ratio with respect to the mounting angle of the crack prevention plate in an experimental example for confirming the crack prevention performance according to an embodiment of the present invention.
6 is a diagram schematically showing another example of a crack prevention device to be employed in the non-shrink mortar crack prevention structure of the abutment device according to the present invention.
7 is a view schematically showing another example of a crack prevention tool to be employed in the non-shrink mortar crack prevention structure of the seating device according to the present invention.
Fig. 8 is a plan view schematically showing a state in which a bridge seating device excluding a crack prevention device is installed and installed on a pier, and illustrates a crack pattern occurring in a concrete mat hardened around the edge of a base plate (or lower plate) .

Objects, specific advantages and novel features of the present invention will become more apparent from the following detailed description and embodiments in connection with the accompanying drawings. In adding reference numerals to elements of each drawing in the present specification, it should be noted that, even though they are indicated on different drawings, only the same elements are to have the same number as possible. In addition, in describing the present invention, when it is determined that a detailed description of related known technologies may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted. In this specification, terms such as first and second are used to distinguish one component from other components, and the component is not limited by the terms. In the accompanying drawings, some components are exaggerated, omitted, or schematically illustrated, and the size of each component does not entirely reflect the actual size.

The present invention relates to a non-shrink mortar crack prevention structure of the abutment device, through a non-shrink mortar mat supplied and poured between the lower plate of the abutment device and the upper part of the pier to maintain a reliable coupling state between the abutment device and the pier. It is characterized in that it is designed to control cracks starting around the edge of the plate, particularly at the edge of the lower plate.

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

The present invention includes a seating device 100 connecting the support object 10 and the installation object 20 as shown in FIGS. 1 to 4, which is widely known to those skilled in the art. As shown, between the upper plate 110 installed under the object to be supported, the lower plate 120 fixed to the upper portion of the object to face the upper plate 110, and the upper plate 110 and the lower plate 120 It consists of a support member 130 to be installed. Here, the support object 10 may be an upper structure (top plate) of a bridge, and may optionally be equipment or equipment such as a rail, a computer server, a communication device, a laboratory device, and a medical device. Correspondingly, the installation object 20 may be a bridge pier (alternate), and may optionally be a sleeper, a ground, a building, or a production line.

In the following detailed description of the present invention, a description will be made on the basis of the abutment device 100 interposed at a contact point between the upper structure of the bridge and the pier supporting its load.

The upper plate 110 is installed and fixed under the upper structure of the bridge, and may be fixed by an anchor. The lower plate 120 may be seated on a bridge seat made of a non-shrink mortar mat 21 on an upper pier corresponding to the installation object 20. Specifically, the lower plate 120 is a non-shrinkable mortar mat 21 (or concrete mat) that is hardened by placing a non-shrinkable mortar on a bed block (or bed concrete; see Fig. 4) on the upper part of the bridge pier as a means of the lower part. A plurality of anchors 121 provided on the lower surface of the plate may be embedded and fixed. A number of anchors 121 are installed adjacent to each corner 120a of the lower plate as shown. The support member 130 is a constituent member that receives the vertical load of the support object 10 from the upper plate 110 and transmits it to the installation object 20 through the lower plate 120, and if necessary, the horizontal and / Or it is possible to add a seismic isolation function by allowing rotational displacement.

Incidentally, the present invention may be any type of abutment device that can be bonded to the upper portion of the installation object 20 by means of a non-shrink mortar mat 21 with a lower plate 120 equipped with an anchor at the bottom of each corner. And, it is not limited to the shape as described above.

As described above, the seating device 100 adheres the lower plate 120 to the installation object 20, that is, to the top of the pier by means of the non-shrink mortar mat 21 formed on the bed block. To this end, the seating device is mounted on the bed block above the pier, and after installing the formwork around the lower plate 120 of the seating device, a non-shrinkable mortar is poured and cured to make contact with the bottom surface of the lower plate 120. It is possible to form a cross seat made of a shrink mortar mat (21). In addition, the non-shrinkable mortar mat 21 is to be supplied through a gap between the lower plate and the groove of the non-shrinkable mortar mat 21 by arranging the abutting device on a groove (not shown) formed concave in the upper surface of the bed block above the pier. It may be formed by pouring and curing non-shrink mortar.

In general, a crack pattern is caused at right angles to the direction of stress acting on the protrusion of a concrete structure, for example, a right angle part, while the resulting crack is continuously or repeatedly caused by external factors such as drying shrinkage and temperature change of the shrinkage mortar. As they are exposed, they grow more. The generated cracks are difficult to repair, cost a lot of maintenance and repair, and have a significant adverse effect on the durability of the structure.

In the abutment part made of the non-shrink mortar mat 21 to which the non-shrink mortar crack prevention structure of the abutment device according to the present invention is not applied, as shown in FIG. 8, an oblique line at each corner 120a of the lower plate 120 ( It can be seen that the concrete crack progresses in the direction of about 45°).

Accordingly, the present invention is characterized in that it is possible to block the spread and progress of cracks occurring at each corner by arranging the crack prevention hole 200 in a preferably diagonal direction around each corner of the lower plate 120 where stress is concentrated. do. The crack prevention device 200 includes a binding portion 210 that helps binding with the anchor 121 and a crack prevention portion 220 that is coupled to the binding portion 210.

Specifically, the binding portion 210 is fastened to the outer peripheral surface of the anchor 121 that extends downward from the lower surface of the lower plate 120 and maintains a fixed state with the installation object 20, for example, the bridge pier 220 It is a component that helps fix the position of ). As shown, the binding portion 210 is formed in an O-ring shape formed in a size and shape capable of accommodating the anchor 121 and the length from the outer peripheral surface of the coupling ring 211 to the outside. It has an extended fastening extension pipe 212. Of course, the coupling ring 211 is not limited thereto, and the coupling ring 211 is sufficient as various types of binding members such as band clamps, ties, etc. that can wrap around the outer circumferential surface of the anchor 121 and help fix the position of the crack prevention tool. Replaceable.

Preferably, the fastening extension pipe 212 may have a female thread (no reference numeral) formed on the inner circumferential surface of the inner hollow.

The crack prevention part 220 includes a crack prevention plate 221 and a fastening protrusion 222 extending in length from the inner peripheral surface of the crack prevention plate 221. Preferably, the crack prevention plate 221 is curved in an arc shape in order to wrap around each corner 120a of the lower plate and cross the longitudinal direction and the transverse direction of the corner so that orthogonal stresses can be collided and dispersed. Has been. In addition, the crack prevention part 220 is formed in the center of the inner circumferential surface of the crack prevention plate 221 formed in an arc shape so as to surround both sides of the crack prevention plate in the same range, centering on the edge 120a of the lower plate 120 It has a fastening protrusion 222 that extends long in the horizontal direction. The crack prevention plate 221 may form a plurality of through holes 221a that allow penetration of the non-shrinkable mortar to be poured and supplied in the inner region thereof.

In addition, the fastening protrusion 222 may form a male thread (no reference numeral) on the outer circumferential surface to be screwed with the fastening extension pipe 212 of the binding portion 210.

As described above, the crack prevention device 200 may be fixed in a mutual screw fastening method by inserting and rotating the fastening protrusion 222 of the crack prevention part 220 into the fastening extension pipe 212 of the binding part 210. . Through this screw fastening method, the crack prevention device 200 is configured to reciprocate the crack prevention part 220 in the longitudinal direction of the fastening extension pipe 212, that is, to move forward and/or backward, so that the crack prevention plate 221 ) And the edge 120a of the lower plate 120 can be adjusted.

The crack prevention device 200 may be changed by rotating the position of the crack prevention part 220 along a circular movement trajectory with the anchor 121 as the center through the coupling ring 211 of the binding part 210. In other words, since the crack prevention part 220 can be disposed to be opposite to the direction in which the crack occurs at each corner 120a of the lower plate, the edge 120a of the lower plate 120 where stress is concentrated The cracks generated in the part are blocked by the crack prevention plate 221 of the crack prevention part 220 to disperse the stress so that the non-shrink mortar mat 21 does not spread further.

In addition, the crack prevention device 200 may be disposed so that the outer peripheral surface of the crack prevention plate 221 is inclined upward. As shown in FIG. 4, by arranging the crack prevention plate 221 at an angle corresponding to the chamfer shape formed along the upper edge of the non-shrink mortar mat 21, between the edge of the non-shrink mortar mat 21 and the crack prevention plate. It is possible to reduce the contraction force of the non-shrink mortar mat by reducing the contraction distance.

At the beginning of curing of the non-shrink mortar mat 21, the moisture evaporates on the upper surface layer of the non-shrink mortar mat, causing a shrinkage effect by drying, whereas the inner layer of the non-shrink mortar mat contains moisture, so the inner layer is The contraction action of the surface layer is restrained, and a tensile force is generated in the surface layer of the non-shrink mortar mat, thereby forming surface cracks. The non-shrink mortar crack prevention structure according to the present invention allows the crack prevention tool 200 to be buried adjacent to the surface layer of the non-shrink mortar mat 21 in order to solve this problem. That is, the upper end of the crack prevention plate 221 may be disposed at the same height (or the same level) as the surface layer of the non-shrink mortar mat 21 (see FIG. 4 ), and the upper end of the crack prevention plate is non-shrinkable. It may be positioned to protrude above the surface layer of the mortar mat to expose the upper end of the crack prevention plate to the outside. Alternatively, the crack prevention device may be buried inside the non-shrinkable mortar mat 21 to avoid exposing the upper end of the crack prevention plate.

When the crack prevention part 220 is buried adjacent to the surface layer of the non-shrinkable mortar mat 21 as described above, the crack prevention plate is deformed or damaged due to unnecessary collisions between the edges of the crack prevention plate 221 and the lower plate. The length (l) of the fastening protrusion 222 can be extended to a length equal to or longer than the distance (d) between the outer circumferential surface of the anchor 121 and the edge 120a so as to prevent the like.

5 is a crack ratio distribution diagram according to varying the mounting angle of the crack prevention plate 221 (see FIG. 1) in an experimental example for confirming the concrete crack prevention performance according to an embodiment of the present invention.

This experiment confirms the crack prevention performance according to the presence or absence of a crack prevention plate on the non-shrink mortar mat 21 that is hardened by pouring the non-shrink mortar, and the non-shrink mortar mat was cured at room temperature.

Here, the crack ratio is a ratio between the tensile strength of the concrete and the temperature stress generated during contraction, which means that the greater the crack ratio, the higher the stabilization of drying shrinkage. In other words, when drying shrinkage is stabilized, the crack prevention effect is expected to improve. For reference, the maximum value of the crack ratio is 20.

5(a) is a distribution diagram illustrating the crack ratio on the non-shrinkable mortar mat 21 without a crack prevention plate, and the average value of the crack ratio measured in the entire area of the non-shrink mortar mat specimen is 9.87.

5(b) is a distribution diagram illustrating the crack ratio on the non-shrink mortar mat 21 equipped with a crack prevention plate, and the mounting angle of the crack prevention plate embedded in the non-shrink mortar mat is set to 0° so that the crack prevention plate is It is installed vertically. The average value of the crack ratio measured in the entire area of the non-shrink mortar mat specimen is 13.5, and a crack prevention effect of 37% can be expected compared to the average crack ratio of the non-shrink mortar mat specimen without a crack prevention plate.

For reference, the mounting angle refers to an angle θ between the end of the fastening protrusion 222 and the virtual vertical line and the crack prevention plate arranged as shown in FIG. 4, and the virtual vertical line forms a right angle with the fastening protrusion. .

5(c) is a distribution diagram illustrating the crack ratio on the non-shrink mortar mat 21 equipped with a crack prevention plate, and the mounting angle of the crack prevention plate embedded in the non-shrink mortar mat is set to 45°. The outer circumferential surface of is placed in an upward slope. The average value of the crack ratio measured in the entire area of the non-shrink mortar mat specimen is 16.5, and a crack prevention effect of 67% can be expected compared to the average crack ratio of the non-shrink mortar mat specimen without a crack prevention plate.

5(d) is a distribution diagram illustrating the crack ratio on the non-shrink mortar mat 21 equipped with a crack prevention plate, and the mounting angle of the crack prevention plate embedded in the non-shrink mortar mat is set to 60° The outer circumferential surface of is placed in an upward slope. The average value of the crack ratio measured in the entire area of the non-shrink mortar mat specimen is 16.9, and a crack prevention effect of 71% can be expected compared to the average crack ratio of the non-shrink mortar mat specimen without a crack prevention plate.

Crack prevention plate
Not equipped Install crack prevention plate (mounting angle, θ) θ= 0° θ= 20° θ= 45° θ= 60° Average crack ratio 9.87 13.5 13.8 16.5 16.9 Rate of increase - 37% 40% 67% 71%

As can be seen from Table 1, the present invention can expect concrete crack prevention performance in the non-shrink mortar mat through the crack prevention plate surrounding each corner of the lower plate of the abutment device, and the mounting angle of the crack prevention plate is virtual Concrete cracks can be more effectively prevented by arranging inclined upward at 0° to 60°, preferably at 45° based on the vertical line.

When the mounting angle (θ) of the crack prevention plate exceeds 60°, the crack prevention plate 221 is disposed substantially the same as the fastening protrusion 222 on the inner circumference of the crack prevention plate in the process of pouring the non-shrink mortar. The accumulated air may not escape and voids may occur, and it will affect the positioning of the crack prevention plate due to the non-shrinkable mortar that rises from the bottom during supply placement.

6 is an exploded perspective view of another example of a crack prevention device 200 to be employed in the non-shrink mortar crack prevention structure of the abutment device according to the present invention as viewed from above and below. The crack prevention tool illustrated in FIG. 6 is another modified example of the crack prevention tool shown in FIGS. 1 to 4, and has a very similar structure except for the shape of the crack prevention plate, so as to help a clear understanding of the present invention Descriptions of similar or identical configurations will be excluded here.

The crack prevention device 200 is screwed to the fastening extension pipe 212 of the fastening part together with the fastening part 210 and consists of a crack preventing part 220 capable of moving forward and/or backward through rotation, wherein the crack preventing part 220 includes a fastening protrusion 222 screwed to the fastening extension pipe 212 and an arc-shaped crack prevention plate 221 (see FIG. 3).

The arc-shaped crack prevention plate 221 includes a protrusion 223 for inducing stress concentration in a triangular cross-sectional shape extending in a vertical direction to the center of the outer peripheral surface thereof. The stress concentration induction protrusion 223 forms a triangular cross-sectional groove in a portion of the non-shrink mortar mat 21 in contact with the outer circumferential surface of the crack prevention plate 221. As is known to those skilled in the art, the load acting on the hardened concrete is concentrated in the areas of weak resistance. Based on this fact, the load acting on the concrete is concentrated in the triangular cross-sectional groove artificially formed in the non-shrink mortar mat 21, so that cracks generated in the non-shrink mortar mat 21 can be minimized. Since the stress concentration induction protrusion 223 is buried in the non-shrink mortar mat 21, it is a soft synthetic resin material that does not have affinity with concrete so that it can respond to internal expansion or contraction deformation after curing of the non-shrink mortar mat. May be made of a stretchable silicone material.

Optionally, the arc-shaped crack prevention plate 221 is further provided with an inner stress concentration induction protrusion (without reference numeral) extending in a vertical direction from the center of the inner circumferential surface to be oriented with the stress concentration induction protrusion 223 You may.

7 is a view showing another example of a crack prevention device to be employed in the non-shrink mortar crack prevention structure of the abutment device according to the present invention, the crack prevention device 200 is a binding portion 210 and a crack prevention portion 220 It consists of (see Fig. 3).

The crack prevention device 200 may form a central portion of the crack prevention plate as an uneven plate 221b in order to relieve stress acting on the crack prevention plate 221. That is, the concave-convex plate (221b) of the crack prevention plate is arranged in a horizontal direction with the fastening protrusion 222 at the center of the inner circumferential surface, so that excessive deformation of the concave-convex plate due to the load acting on the concrete through the fastening protrusion can be prevented. have.

The present invention has been described in detail through examples, but this is for explaining the present invention in detail, and the non-shrink mortar crack prevention structure of the abutment device according to the present invention is not limited thereto, and is within the technical scope of the present invention. It will be clear that the transformation or improvement is possible by those with ordinary knowledge in the field.

All simple modifications or changes of the present invention belong to the scope of the present invention, and the specific scope of protection of the present invention will be made clear by the appended claims.

10 ----- support object,
20 ----- object to be installed,
21 ----- non-shrink mortar mat,
100 ----- seating system,
110 ----- top plate,
120 ----- lower plate,
130 ----- support member,
200 ----- crack prevention hole,
210 ----- Binding,
220 ----- Crack prevention part.

Claims (7)

Each corner 120a includes a lower plate 120 having an anchor 121 on a lower surface thereof, and the anchor 121 of the lower plate 120 is embedded in the non-shrink mortar mat 21 while the lower plate ( In the seating device 100 for adhering 120) to the upper portion of the installation object 20,
A binding portion having a coupling ring 211 fastened to the outer circumferential surface of the anchor 121, and a coupling extension pipe 212 extending in the outer direction from the coupling ring 211 and having a female thread formed on the inner circumferential surface of the inner hollow ( 210) and;
A crack prevention plate 221 curved in an arc shape for stress distribution, and a length extending from the inner circumferential surface of the crack prevention plate 221 and inserted into the inner hollow of the fastening extension pipe 212 to the outer circumferential surface to be screwed. It includes a crack prevention device 200 consisting of; a crack prevention part 220 having a fastening protrusion 222 formed with a male thread,
The crack prevention part 220 is coupled to be movable forward or backward along the longitudinal direction of the fastening extension pipe 212 of the binding part 210 by screw rotation,
The crack prevention device 200 is disposed to be embedded in the non-shrink mortar mat 21 so as to surround each corner 120a of the lower plate 120, A non-shrink mortar crack prevention structure of a seating device, characterized in that it controls cracks occurring in the non-shrink mortar mat hardened around each corner.
delete delete The method according to claim 1,
The crack prevention part 220 is characterized in that the crack prevention plate 221 is arranged to be inclined upward at 0° to 60°, preferably 45° based on a virtual vertical line at the end of the fastening protrusion 222 Non-shrink mortar crack prevention structure of the seating device.
The method according to claim 1,
The crack prevention plate 221 is a non-shrink mortar crack prevention structure of a seating device, characterized in that it further comprises a protrusion 223 for inducing stress concentration in a triangular cross-sectional shape extending in a vertical direction from the center of the outer peripheral surface.
The method according to claim 1,
The crack prevention plate 221 is a non-shrink mortar crack prevention structure of a seating device, characterized in that an uneven shape plate (221b) is additionally disposed at the center of the crack prevention plate.
The method according to claim 1,
The seating device 100 is installed between the support object 10 and the installation object 20, and faces the upper plate 110 installed under the support object 10 and the upper plate 110 And a lower plate 120 fixed to an upper portion of the installation object to be installed, and a support member 130 installed between the upper plate and the lower plate to support the upper plate and accommodate the displacement of the upper plate. Non-shrink mortar crack prevention structure of the seating device, characterized by.

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