JP4628736B2 - Torsion prevention mechanism for base-isolated buildings - Google Patents

Description

  The present invention relates to a twist prevention mechanism for a base-isolated building.

  The seismic isolation bearing and arm-rotating friction damper are placed between the foundation of the building and the upper structure, and the upper structure is isolated in the horizontal two-dimensional direction by the seismic isolation, and the arm rotates. 2. Description of the Related Art Base-isolated buildings in which vibrations during base isolation are attenuated by a type friction damper are conventionally known.

  However, in such a base-isolated building, it is necessary to satisfy strict eccentricity regulations in order to prevent the upper structure from twisting in the horizontal direction with respect to the foundation due to the base-isolating operation. There is a problem that various restrictions are imposed and the degree of freedom in designing the building and the seismic isolation layer is narrowed.

  Therefore, it is conceivable to incorporate a mechanism for preventing torsion into each seismic isolation bearing, but each seismic isolation bearing has a plane size that is considerably smaller than the plane size of the building. There is a limit to increasing the lever length of the moment, and there is a problem that it is difficult to obtain a large torsional resistance even if a torsion prevention mechanism is incorporated in the seismic isolation bearing unit alone.

  The torsion prevention mechanism part inevitably has mechanical backlash in the torsion prevention direction. However, if the structure is incorporated in each seismic isolation bearing part that is small in size, the small backlash will not occur. There is also a problem that the upper structure portion of the building is amplified as a large backlash in the twisting direction, and the upper structure portion of the building is greatly twisted and moved by the amplified backlash.

  In view of the problems as described above, the present invention can obtain a large torsion resistance, and can reduce the movement of the upper structure portion in the torsional direction due to mechanical backlash. It is an object of the present invention to provide a torsion prevention mechanism in a base-isolated building that can be realized by the mechanism.

  In the above problems, the present inventor, in the course of repeated investigation and research, under the specific conditions, the arm of a plurality of arm-rotating friction dampers provided in a distributed arrangement state in a horizontal two-dimensional direction The fact that the torsional stiffening resistance moment can be generated by connecting them with a connecting material has been found, and the present invention has been completed.

That is, according to the present invention, the seismic isolation bearing part and the arm-rotating friction damper are arranged between the lower structure part and the upper structure part, and the upper structure part is seismically isolated in the horizontal two-dimensional direction by the seismic isolation support part. And a torsion prevention mechanism in a base-isolated building in which vibration at the time of base isolation is attenuated by an arm rotation type friction damper,
At least two arm-rotating friction dampers are provided so as to be dispersedly arranged in a horizontal two-dimensional direction, and the arms of both arm-rotating friction dampers are connected by a connecting material. The content of the present invention is a torsion prevention mechanism for a seismic isolation building (first invention) characterized in that the relative torsional motion between the lower structure portion and the upper structure portion during an earthquake is restricted.

  In this mechanism, the relative twisting motion between the lower structure part and the upper structure part is regulated by connecting the arm-rotating friction dampers that are arranged in a distributed state in the two-dimensional horizontal direction with a connecting material. Therefore, it is possible to increase the lever length of the torsional stiffening resistance moment when the superstructure tries to twist, and thereby torsion that far exceeds the expectation so far Strength can be obtained, and the degree of freedom in designing buildings and seismic isolation layers can be increased.

  Moreover, since it is a mechanism that connects the arm-rotating friction dampers distributed in the horizontal two-dimensional direction with a connecting material, the torsion prevention mechanism part is large in size and inevitably exists in the torsion prevention mechanism part. The torsional backlash of the superstructure of the building, which is amplified by the small mechanical backlash of the torsion, can be kept small, and the torsional movement of the superstructure by such backlash is extremely small be able to.

  In addition, two of the arm-rotating friction dampers provided in the base-isolated building are used, and the arms of these dampers are simply connected by a connecting material, so that they can be realized with a simple mechanism. Can do.

  In the mechanism of the first invention, the connecting member may be connected to the arm at a position away from the friction rotation center region of the arm rotation type friction damper (second invention). In that case, the connecting material can be connected without changing the structure of the frictional rotation center region, and the design and manufacture of the twist prevention mechanism can be facilitated.

  Since the present invention is as described above, it is possible to obtain a large torsion resistance, and to reduce the movement of the upper structure portion in the torsional direction due to mechanical backlash. It can be realized with a mechanism.

  Next, the best mode for carrying out the present invention will be described with reference to the drawings.

  The torsion prevention mechanism 1 according to the first embodiment shown in FIGS. 1 and 2 includes a base isolation structure and an arm-rotating friction damper disposed between a foundation as a lower structure section and an upper structure section. The upper structure is seismically isolated in the horizontal two-dimensional direction at the bearing, and the arm rotation type friction damper is provided in a seismically isolated building that is designed to attenuate vibration during isolation. The rotary friction dampers 2 and 2 and the connecting material 3 are included.

  As shown in FIG. 1, each arm-rotating friction damper 2 is a so-called pantograph type in which the arms 4 are assembled in a rhombus shape in a horizontal plane, and the ends of the adjacent arms 4, 4 are arranged as needed. In a state where a friction ring or the like is interposed, the bolts 5 are fastened together and are rotatably connected, and one of the diagonal portions of one pair is connected to the base 7 side by the bracket 6. The other of the diagonal portions is connected to the upper structure portion 8 side by the bracket 6, and when the base 7 and the upper structure portion 8 are moved relative to each other in the horizontal direction by seismic isolation, the bolts 5 are tightened together. Further, each joint portion of the arms 4 is rotated against the tightening force by the bolts 5 and the horizontal vibration due to the seismic isolation is attenuated by the friction force at that time. The damper may be one in which the arms are assembled in a rhombus shape in the vertical direction.

  The two arm-rotating friction dampers 2 and 2 are set to have the same arm length between the joint portions, and the arm opening angles at the joint portions are also set to be the same, and in the horizontal plane. If the upper structure 8 does not move in the torsional direction during the relative movement in the horizontal direction by seismic isolation between the foundation 7 and the upper structure 8, the same direction can be applied. Arms 4a, 4a are arranged so as to move in the same manner.

  The connecting member 3 connects a pair of corresponding arms 4a and 4a of the two arm-rotating friction dampers 2 and 2 to keep the distance between them constant. In the present embodiment, the connecting member 3 is linear. For example, a metal material such as a steel bar that can withstand both compression and tension is used as the connection material.

  As shown in FIG. 2 (b), the end portion 3a of the connecting member 3 is bent into a bowl shape, and the arm 4a has a joint portion which is a friction rotation center region of the damper 2. The insertion hole 9 is opened at a position away from the connecting member 3, and the connecting member 3 and the arm 4a are installed in a state in which the connecting member 3 is inserted into the inserting hole 9 of the arm 4a with the end flange part 3a from above. It is connected.

  According to the torsion prevention mechanism 1 described above, during the seismic isolation operation due to the earthquake, the upper structure portion tends to twist relative to the foundation, and the corresponding arms 4a and 4a provided in the two dampers 2 and 2 are provided. Try to move differently from each other, the connecting material 3 works to prevent it by compression or tension to generate a torsional stiffening moment, which prevents the upper structure 8 from moving in the torsional direction. Is done.

  As described above, in the torsion prevention mechanism 1 described above, the base 7 and the upper structure portion 8 are obtained by connecting the two arm-rotating friction dampers 2 provided so as to be dispersedly arranged in the horizontal direction by the connecting material 3. Therefore, the lever length of the torsional stiffening resistance moment when the upper structure portion 8 tries to perform the torsional operation can be increased. Can provide a large torsional strength that far exceeds expectations, and can also increase the degree of freedom in designing buildings and seismic isolation layers, as well as the degree of freedom in arranging furniture, etc. in buildings. .

  In addition, since it is a mechanism for connecting the arm-rotating friction dampers 2 and 2 that are arranged in a distributed manner in the horizontal direction with the connecting material 3, the torsion prevention mechanism is large in size, and the torsion prevention mechanism The backlash in the torsional direction of the upper structure part 8 of the building, which is amplified by the mechanical backlash that is unavoidably present in the part, can be reduced, and the torsional direction of the upper structure part 8 due to such backlash Can be made extremely small.

  And since two of the arm rotation type friction dampers provided in the seismic isolation building are used and the arms 4a and 4a of these dampers 2 and 2 are simply connected by the connecting material 3, a simple mechanism Can realize them.

  In particular, the connecting member 3 is connected to the arm 4a at a position away from the joint portion which is the friction rotation center region of the arm rotation type friction damper 2, so that the structure of the friction rotation center region is changed. It is possible to connect the connecting members without any trouble, and to facilitate the design and manufacture of the twist prevention mechanism. Specifically, for example, as described above, the twist prevention mechanism described above can be obtained simply by opening the insertion hole 9 in the corresponding arm 4a of each arm-rotating friction damper 2 and inserting the hook-shaped end portion 3a of the connecting member 3. 1 can be configured.

  The twist preventing mechanism 1 of the second embodiment shown in FIG. 3 (a) is provided with two connecting members 3, and two sets of arms 4a, 4a; 4b, 4b corresponding to the arm rotating friction dampers 2, 2. These are connected by these connecting materials 3 and 3.

  In addition, the twist preventing mechanism 1 of the third embodiment shown in FIG. 3 (b) is configured such that the arm-rotating friction damper 2 is a V-shaped damper in which the arms 4 and 4 are assembled in a V-shape in a horizontal plane. A corresponding pair of arms 4 a and 4 a are connected by a connecting material 3.

  Although the embodiment of the present invention has been described above, the present invention is not limited to this, and various modifications can be made without departing from the spirit of the invention. For example, in the above-described embodiment, the case where the arm-rotating friction damper 2 is configured to generate a frictional force by tightening the joint portion, which is the center portion of the friction rotation, with the bolts 5. However, you may consist of what was tightened by the spring force by a spring.

  In the above-described embodiment, the connecting member 3 and the arm 4a are connected by the insertion hole 9 and the hook-shaped end portion. However, the present invention is not limited to this, and may be connected by various connecting means. .

  Further, in the above-described embodiment, the case where the connecting member 3 is connected to the arm 4a at a position away from the joint portion that is the frictional rotation center portion is shown. You may connect in the joint part which is a dynamic center part, In that case, it does not ask | require whether the connection material 3 is directly connected with the arm, or is connected artically. That is, in the first invention, the phrase “the arms are connected by a connecting material” should be interpreted in such a meaning.

  In the above embodiment, the corresponding arms 4a and 4a of the two arm-rotating friction dampers 2 and 2 are connected to each other by the connecting material 3, but three or more arm-rotating friction dampers are used. Corresponding arms may be connected by a connecting material.

  Further, in a group of a plurality of arm-rotating friction dampers that perform a damping action in one horizontal direction, the arms of the two arm-rotating friction dampers are connected by a connecting material, and a horizontal direction orthogonal to the above direction In the group of a plurality of arm-rotating friction dampers that perform a damping action, the arms of two arm-rotating friction dampers may be connected by a connecting material.

  Moreover, in the above embodiment, the case where the arms are connected with a tie material that can withstand both tension and compression has been shown, but by combining a plurality of tie materials that can withstand tension but cannot withstand compression, twisting in both directions can be achieved. You may be able to respond.

  Furthermore, the torsion prevention mechanism of the present invention may be incorporated in a building together with an arm-rotating friction damper in building construction, or in addition, for example, provided in an existing seismic isolation building. It may be constituted by connecting the arm-rotating friction dampers connected by a connecting material.

It is a partial cross section top view which shows the twist prevention mechanism of 1st Embodiment. It is the same section sectional front view. FIG. 1A is a partial cross-sectional plan view showing the twist prevention mechanism of the second embodiment, and FIG. 2B is a partial cross-sectional plan view showing the twist prevention mechanism of the third embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Torsion prevention mechanism 2 ... Arm rotation type friction damper 3 ... Connecting material 4a ... Corresponding arm 7 ... Foundation (lower structure part)
8 ... Upper structure

Claims (1)

A seismic isolation bearing and an arm-rotating friction damper are placed between the lower structure and the upper structure, and the upper structure is isolated in the horizontal two-dimensional direction by the seismic isolation, and the arm rotates. A torsion prevention mechanism for base-isolated buildings that is designed to attenuate vibrations during base isolation with a friction damper,
The arm-rotating friction damper is provided with at least two in a distributed arrangement state in a horizontal two-dimensional direction,
The arm of each arm rotation type friction damper has a joint hole that opens upward at a position away from the joint, which is the friction rotation center region of the damper, and the end is bent into a hook shape. The end flange of the material is installed in a state where it is inserted from above into the insertion hole of the arm of each arm rotation type friction damper, and the arms are connected to each other. A torsion-preventing mechanism for a base-isolated building, characterized in that the relative torsional motion with the upper structure is restricted.

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