JPH10311029A - Base isolation structure for concrete rod type body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To protect a body structure against a breakage due to a load at a level 2 as far as practicable by providing a part of a concrete rod type body with a brittle part made of a laminated ring. SOLUTION: A laminated ring 1 secured to the periphery of a part of a concrete rod type body 13 is positioned so as to have a lamination center axis approximately matched with the lengthwise center axis of the rod type body 13, and the fitting position of the laminated ring 1 forms a brittle part 14 having a thin wall of concrete in relation to the rod type body 12. The material of an annular plate 2 forming the laminated ring 1 is steel, aluminum alloy or the like, and the shape thereof may be polygonal annular type. As a result, even when an excessive shearing load at a level 2 acts, the laminated ring 1 of the brittle part 14 is dislocated to absorb the load and prevent the breakage of the rod type body 12, or the extent of the breakage, if any, can be lessened.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a concrete rod-shaped structure such as a pile, a pole, a tower or a chimney which is installed vertically or substantially vertically in the ground or on the ground, and a building or the like mounted on the pile, which is subjected to an earthquake. And concrete seismic isolation structures to protect against natural disasters.

[0002]

2. Description of the Related Art Conventionally, piles installed underground or on the ground,
Concrete rods such as poles, towers, chimneys, etc., except for special cases such as nuclear facilities, are generally subject to vibrating external forces (e.g., earthquake or wind) that can occur stochastically once or twice within the service period of the structure. Hereinafter, it is designed to withstand the “level 1 load”. However, as in the case of the recent Great Hanshin-Awaji Earthquake, the probability of occurrence during the service period is extremely low, but a vibrating external force having a large strength far exceeding the level 1 load (hereinafter referred to as “level 2 load”) The above-mentioned concrete rod-shaped structure is becoming a social situation that cannot be overlooked.

However, in view of such a social situation, in many structures, the design load of Level 1 is increased by using a high-strength material or a member having a large cross section in order to enhance the seismic strength. The design philosophy is moving towards paying a costly price in case of the very small event that can happen.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has the advantage of utilizing the characteristics of a rod-shaped structure without paying a costly cost.
It is an object of the present invention to provide a seismic isolation structure of a concrete rod-like body capable of protecting a main body structure portion (including a building above a pile in the case of a pile) from destruction as much as possible against a level 2 load.

[0005]

The seismic isolation structure for a concrete rod according to the present invention is conventionally designed to have a seismic strength against a level 1 load, and moreover, a part of the concrete rod is provided. , By providing a weak portion as a discontinuous portion, when an excessive shear load of level 2 is applied in a direction perpendicular to the longitudinal axis of the rod, the weak portion is caused before linear bending of level 1 to failure. Absorbs Level 2 loads and protects the concrete rod body as much as possible from destruction, and in the case of piles installed underground, greatly reduces the propagation of Level 2 loads to overlying buildings, etc. It is characterized by reduction.

The fragile portion is formed by stacking a plurality of annular plates around a part of the body of the rod body and binding them with a binding material to such an extent that they do not fall apart during handling. It is disposed so as to substantially coincide with the longitudinal center axis of the body. This causes a shift between the layers in the laminated ring with respect to the level 2 excess shear load, and serves to absorb unexpected loads and energy. Also,
The laminated ring may be formed by binding spiral plates in the direction of the central axis of the spiral.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be specifically described below with reference to FIGS. FIG. 1A shows a laminated ring 1 serving as a seismic isolation device according to the present invention. The laminated ring 1 has a circular annular plate 2 of the same shape (a contact surface of the annular plate 2 has Listing and Level 2
And several tens of them are stacked on top of each other by applying various lubricants to maintain the friction coefficient determined by design based on the relationship between the load of the concrete and the shear strength of the concrete rod. In the stacking and laminating direction of the laminating ring 1, several parts are bound at substantially equal intervals by a binding member 3. The binding member 3 includes a bolt, a nut, and an iron wire. When an iron wire is used, the upper and lower ends of the iron wire are crimped to bind the laminated rings 1 to such an extent that they are not separated.

Next, an outline of a manufacturing process showing an example in which the above-mentioned laminated ring 1 is disposed on a concrete rod so as to have a seismic isolation function will be described with reference to FIGS. First, a straight steel wire for wiring a cylindrical cage 4 serving as a reinforcing core material of a concrete rod-shaped body so as to surround it in a direction corresponding to the length of the concrete rod-shaped body, and a circular shape of the steel wire And a spiral steel wire that is wired so as to surround the wire (see FIG. 2). The outer diameter of the cylindrical cage body 4 thus braided is formed smaller than the inner diameter of the lamination ring 1 described above. Next, the mold 5 for molding the concrete rod-shaped body is a set of half molds 6 and 7 each having a semicircular cross-sectional shape and divided into half in the longitudinal direction. The cylindrical cage 4 is inserted into one of the half mold frames 6. At this time, the outer periphery of the cylindrical cage 4 of a concrete rod-like body to be provided with a seismic isolation function is provided. The above-described lamination ring 1 is attached to the site in advance (see FIG. 3). After that, the other half mold frame 7 is covered, and the flanges of both mold frames 6 and 7 are fixed by bolting to form the cylindrical mold 5 and the braided steel wire of the cage 4 is subjected to a tension treatment. Then, concrete is injected into the mold 5 from one end by the pump 8 (see FIG. 5).

[0009] Next, the mold 5 into which the concrete has been injected.
Is placed on the roller turntable 9 while lying on its side (see FIG. 6). As a result, the mold 5 gradually rotates at a high speed due to the rotation of the rollers 10, 10 arranged so as to be sandwiched from both sides on the table. As a result, the concrete in the mold 5 is subjected to the action of centrifugal force and the inner wall of the form 5 To the inside and the hollow 11
Is formed. Finally, after the concrete is solidified by steam curing, it is released from the mold (see FIG. 7) to obtain the concrete rod 13 having the seismic isolation structure according to the present invention (FIG. 8A).
(B)).

The molding of the concrete rod-shaped body is not limited to the centrifugal molding method described above, and a method of producing concrete by injecting and filling concrete between the outer mold frame and the inner mold frame may be adopted. . The cylindrical cage formed by braiding the steel wires reinforces the concrete rod-shaped body 12 so as to correspond to the strength against the load of level 1, and the thickness and the number of the steel wires are set according to the purpose of the reinforcement.

The concrete rod 1 thus obtained
The laminated ring 1 fixed to a part of the periphery of the rod 3 is mounted so that the laminating central axis substantially coincides with the longitudinal central axis of the rod-shaped body. In relation to the main body 12, the fragile portion 14 is formed by thinning concrete. Therefore, level 2
When a shear load is applied, the fragile portion 14 undergoes shear deformation, for example, as shown in FIG. 9, the residual deformation amount after the load history becomes 0 to appear as a displacement from the time when the laminated ring is broken. However, the concrete rod body 12 is free from destruction.

The material of the annular plate 2 forming the laminated ring 1 is steel, aluminum alloy, or the like, and the shape may be a polygonal annular shape. Further, the fragile portions 14 may be provided at several places at intervals in the longitudinal direction of the concrete rod. Further, the lamination ring may be a lamination ring 21 formed by binding spiral plates 22 in the direction of the central axis 23 of the spiral as shown in FIG.

[0013]

According to the present invention, if a fragile portion composed of a laminated ring is provided on a part of a concrete rod-shaped body as described above, the laminated ring of the fragile portion is displaced even when a level 2 excess shear load is applied. By absorbing the load, the concrete rod-shaped body can be prevented from being destroyed beforehand, or even if it does, the degree of the damage can be reduced, and the secondary damage caused by the failure can be minimized. On the other hand, if the pile is limited, the acceleration of the seismic force transmitted to the above-mentioned building or the like is reduced, so that the cross section of each member of the building or the like can be reduced, and an economical design is expected.

When the pile is used as an underground pile, if the fragile portion is installed near a location where a moment such as a pile head is large, or at a geological change point where there is a possibility of liquefaction of the ground, lateral flow, and landslide, etc. However, a passive earth pressure greater than the working earth pressure can be expected as a reaction. Further, if a fragile portion is installed near the ground at a pole on the ground, the collision energy of an automobile or the like can be absorbed by being shifted. Furthermore, if a vulnerable part is installed near the ground in a tower or a chimney, unexpected energy such as an earthquake or wind transmitted from the ground can be effectively absorbed.

[Brief description of the drawings]

FIGS. 1A and 1B are a perspective view showing a laminated ring made of an annular plate as a representative example of a seismic isolation device of the present invention, and a perspective view showing a laminated ring made of a spiral plate as another example. It is.

FIG. 2 is a schematic perspective view showing one of the steps of producing the concrete rod-shaped body of the present invention, and showing a steel wire braiding step at the time of forming a cage.

FIG. 3 is a schematic perspective view showing a molding step.

FIG. 4 is a schematic perspective view showing a steel wire tensioning step.

FIG. 5 is a schematic perspective view showing a concrete pouring step.

FIG. 6 is a schematic perspective view showing a centrifugal compaction step.

FIG. 7 is a schematic perspective view showing a demolding step.

8 (a) and (b) are a perspective view and a sectional view taken along line AA of a concrete rod-shaped body according to the present invention.

FIG. 9 is an explanatory diagram showing an example of a state when a load of level 2 is applied.

[Explanation of symbols]

 1, 21 laminated ring 2 annular plate 12 rod-shaped body 14 fragile portion 22 helical plate 23 central axis of spiral

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI // B28B 23/00 B28B 23/18 23/18 F16F 15/06 E

Claims (3)

[Claims] 1. A laminating ring (1) in which a plurality of annular plates (2) are stacked and bound in a stacking direction on a part of a peripheral portion of a rod-shaped main body (12). A seismic isolation structure for a concrete rod-shaped body, comprising a fragile portion (14) disposed so as to substantially coincide with the longitudinal center axis of (12). 2. A laminated ring (21) in which a helical plate (22) is bound in the direction of a central axis (23) of a spiral is provided at a part of the periphery of the rod-shaped body (12). A seismic isolation structure for a concrete rod-shaped body, comprising a fragile portion (14) disposed so as to substantially coincide with the longitudinal center axis of the body (12). 3. The bar-shaped body (1) wherein the fragile portion (14) is
3. The seismic isolation structure for a concrete rod-shaped body according to claim 1, wherein a plurality of places are provided while keeping an interval in the longitudinal direction of 2).