JP7711021B2 - Vibration control structure of building frame - Google Patents

Description

The present invention relates to a vibration control structure for a building frame that can efficiently control the vibration of the building frame against vibration input and effectively suppress torsion that occurs in the building frame.

There are various technologies for improving the vibration control effect of buildings, for example, Patent Documents 1 and 2 are known.

The "flexural deformation control type vibration control frame" in Patent Document 1 is composed of wall columns consisting of multi-story earthquake-resistant elements connected to wall beams that protrude horizontally at the top, connecting columns that rise from the tip of the wall beams on a plane and are insulated from the wall beams, and a vibration control device that is installed between the tip of the wall beam and the top of the connecting column and generates a damping force when there is relative displacement between the tip of the wall beam and the top of the connecting column, or a pair of wall columns whose wall beams face each other, and a vibration control device that is installed between the tips of the wall beams of both wall columns, and is configured by aggregating the columns inside the building into the wall columns and the beams into the wall beams.

In the "vibration control structure" of Patent Document 2, the structure is a steel-reinforced concrete building with three underground floors supported by foundations and a rigid frame structure made up of columns and beams, and the lower ends of the wall-like members are firmly fixed, suppressing deformation of the wall-like members due to the reaction force of the damper, thereby suppressing a decrease in the amount of expansion and contraction (deformation) of the damper due to deformation of the wall-like members, and improving the vibration control effect.

Japanese Patent Application Publication No. 8-60895 JP 2015-94076 A

When a horizontal vibration external force such as an earthquake is input to a building frame, the building frame not only sways laterally in the main direction of the vibration input, but it is known that the building frame also twists around its center of rigidity in a plane that crosses the building frame horizontally. There was a need for a measure to efficiently dampen the building frame against vibration input while at the same time effectively suppressing twisting of the building frame.

The present invention was devised in consideration of the above-mentioned problems with the conventional structure, and aims to provide a vibration control structure for a building frame that can efficiently control the vibration of the building frame against vibration input and effectively suppress torsion that occurs in the building frame.

The vibration control structure for a building frame according to the present invention is a vibration control structure for controlling vibration input of a building frame constructed with its lower part fixed to the ground, and is characterized in that it comprises a pair of sub-frames arranged on both sides of the building frame along the height direction of the building frame, with their tops rigidly connected to the top of the building frame and their bottoms spaced above the ground to form an integrated vibration system with the building frame, each of which is suspended and supported from the top of the building frame, with the rigidity of the top of the building frame set to be higher than that of the other parts of the building frame, and in each gap between the lower part of each of these sub-frames and the lower part of the building frame, a vibration damping device is provided, with one end connected to the building frame and the other end connected to the sub-frame, arranged in a direction along the rigidity center of the building frame in a plane along the ground surface.

The stiffness centers of the pair of sub-frames in a plane along the ground surface are all arranged on a straight line passing through the stiffness center of the building frame, and the vibration damping devices are arranged in pairs on either side of the straight line passing through the stiffness center of the building frame, and the arrangement of these vibration damping devices is characterized in that at least a tangent to a circle centered on the stiffness center of the building frame is oriented so that a vibration damping effect occurs in a direction passing through the stiffness centers of the pair of sub-frames.

When the distance from the rigidity center of one of the sub-frames to the rigidity center of the building frame is La, and the distance from the rigidity center of the other sub-frame to the rigidity center of the building frame is Lb, the damping performance Fa of the vibration damping device connected to one of the sub-frames and the damping performance Fb of the vibration damping device connected to the other sub-frame are set to have a relationship of La x Fb = Lb x Fa.

The vibration control structure for a building frame of the present invention can efficiently control the vibration of the building frame against vibration input, and can effectively suppress torsion that occurs in the building frame.

1 is a front view showing a preferred embodiment of a vibration control structure for a building frame according to the present invention. FIG. 2 is a side view of the vibration control structure for the building frame shown in FIG. 1 . This is a view taken along line AA in FIG. This is a view taken along line BB in FIG. FIG. 2 is an explanatory diagram illustrating a vibration system of the vibration control structure of the building frame shown in FIG. 1 . 2 is a schematic plan view illustrating an arrangement of a vibration damping device provided in the vibration damping structure for the building frame shown in FIG. 1. FIG. 7 is a schematic plan view illustrating an example of the arrangement of the vibration damping device in the attachment region, with respect to the arrangement mode of the vibration damping device shown in FIG. 6 . FIG. 2 is an explanatory diagram illustrating an example of the vibration control structure for the building frame shown in FIG. 1 in which the center of rigidity of the building frame is offset from the centroid of the building frame. FIG. 2 is an explanatory diagram illustrating another example of the vibration control structure for the building frame shown in FIG. 1, in which the center of rigidity of the building frame is shifted from the centroid of the building frame.

Below, a preferred embodiment of the vibration control structure for a building frame according to the present invention will be described in detail with reference to the attached drawings.

Figure 1 is a front view showing a preferred embodiment of a vibration-damping structure for a building frame according to the present invention, Figure 2 is a side view of the vibration-damping structure for a building frame shown in Figure 1, Figure 3 is a view taken along line A-A in Figure 1, and Figure 4 is a view taken along line B-B in Figure 1.

The building frame 1, which is the target of vibration control, is constructed using a well-known column-and-beam structure such as steel frame, reinforced concrete, steel-reinforced concrete, or steel-concrete.

The building frame 1 may be a new building or an existing building. In the illustrated example, the building frame 1 is shown as a rectangular parallelepiped.

The building frame 1 is constructed such that the lower part 1a in the height direction of the building frame 1 is rigidly fixed to the ground G, and horizontal external vibration forces such as earthquake motion are input to the building frame 1 through the lower part 1a.

In such a building frame 1, horizontal vibration occurs, with the building swaying sideways in the main direction of the vibration input.

The vibration control structure of the building frame according to this embodiment is configured to efficiently control the horizontal vibrations that occur in the building frame 1 by using the sub-frame 2 described below, and furthermore, by providing the sub-frame 2, when the vibration control action is in operation, the torsion D of the building frame 1 that occurs around the center of rigidity R1 of the building frame 1 in a plane that horizontally crosses the building frame 1, i.e., in a plane along the ground surface E, can also be effectively suppressed.

A pair of sub-frames 2, 2 of the same dimensions and weight are provided on both sides of the building frame 1. Both sides of the building frame 1 may mean both sides in the length direction, both sides in the width direction, or both sides in both the width direction and length direction on the plane of the building frame 1. In the illustrated example, the sub-frames 2, 2 are provided on both sides in the length direction of the building frame.

When the pair of sub-frames 2, 2 are provided on both sides of the building frame 1, it is desirable to install them so that the center of rigidity R1 of the building frame 1 itself is not displaced by the sub-frames 2, 2.

In other words, it is preferable that the pair of sub-frames 2, 2 are evenly positioned around the rigidity center R1 of the building frame 1.

However, by providing a pair of sub-frames 2, 2 to the building frame 1, the center of rigidity R1 of the building frame 1 may be moved, in which case the position after the movement is regarded as the center of rigidity R1 of the building frame 1.

In other words, in this specification, the center of rigidity R1 of the building frame 1 refers to the center of rigidity after the pair of sub-frames 2, 2 are attached to the building frame 1.

The secondary structure 2 is constructed using well-known column and beam structures such as steel frame, reinforced concrete, steel reinforced concrete, and steel concrete.

The sub-structure 2 is formed along the height direction of the building structure 1, from the top 1b to the bottom 1a of the building structure 1, with a length shorter than the height of the building structure 1.

Specifically, the sub-frame 2 is constructed so that the top 2a, which is the highest part of the sub-frame 2, is located at approximately the same height as the top 1b, which is the highest part of the building frame 1, and the lower part 2b of the sub-frame 2 is spaced upward from the ground G, so that the lower end of the sub-frame 2 is higher than the lower end of the building frame 1 fixed to the ground G. In the illustrated example, each sub-frame 2, 2 is shown as a rectangular parallelepiped that is elongated in the height direction of the building frame 1.

The sub-frame 2 is rigidly connected at its top 2a to the top 1b of the building frame 1 so as to form an integrated vibration system with the building frame 1.

When the top 2a of the sub-frame 2 and the top 1b of the building frame 1 are rigidly connected, the horizontal vibration of the building frame 1 is transmitted directly to the sub-frame 2 without being damped.

In other words, rigid connection means forming a vibration system in which a sub-frame 2 is connected to the top 1b of a building frame 1, as shown in Figure 5.

In the vibration control structure of the building frame of this embodiment, the tops 1b and 2a of the building frame 1 and the sub-frame 2 are rigidly joined together, so that the sub-frame 2 is placed in a folded position relative to the building frame 1 in a parallel relationship with the building frame 1.

In this vibration system consisting of a building frame 1 and a sub-frame 2, the lower part 1a of the building frame 1, which is fixed to the ground G, is the fixed end, and the assumed uppermost part 2b of the sub-frame 2, which is rigidly connected to the top part 1b of the building frame 1 (the lower part of the sub-frame 2 in the folded-back position in this embodiment), is the free end.

When horizontal vibration is input to the building frame 1, the maximum displacement (maximum amplitude) of the horizontal vibration occurs at the assumed top 2b of the sub-frame 2, which is the free end (the lower part of the sub-frame 2 in the folded-back position in this embodiment).

Regarding the rigid joint connecting the top 2a of the sub-frame 2 and the top 1b of the building frame 1, since there are no components or materials with "zero" damping, it means that it is sufficient to transmit vibrations between the building frame 1 and the sub-frame 2 with as little damping as possible.

The sub-frame 2 also functions as a weight connected to the vibration damping device 3 (described later) for the building frame 1, which is the target of vibration damping, in a vibration system integrated with the building frame 1. The weight of the sub-frame 2 is preferably 3.5 to 50% of the weight of the main frame 1.

A gap S is provided between the lower part 2b, 2b of each of the sub-frames 2, 2, which form an integral vibration system with the building frame 1 and whose lower part 2b is the free end of the vibration system, and the lower part 1a of the building frame 1 that faces the lower part 2b, 2b of the sub-frames 2, 2.

In these gaps S, as shown by the symbol F in Figures 1, 2, and 4, an attachment area is set for attaching a vibration damping device 3 that is connected at one end to the sub-frame 2 and at the other end to the building frame 1, and that damps horizontal vibrations that are transmitted from the building frame 1 to the sub-frame 2 via a rigid joint and occur in the sub-frame 2.

In other words, by providing the building frame 1 with the sub-frame 2 and vibration damping device 3, the building frame 1 is configured to dampen vibrations against horizontal vibration input, with the sub-frame 2 acting as a mass element and the vibration damping device 3 acting as a damping element for the building frame 1, which is a spring system.

The vibration damping device 3 damps the vibrations that occur at the lower part 2b of the sub-frame 2, which is the free end where the maximum displacement occurs in the integrated vibration system, while being supported by the building frame 1.

The vibrations that are damped by the vibration damping device 3 can, of course, be any vibrations that occur in the sub-frame 2 relative to the building frame 1.

The vibration damping device 3 may be any of a variety of well-known devices, such as an oil damper that expands and contracts between the building frame 1 and the sub-frame 2 to damp vibrations.

The vibration damping device 3 is also arranged around the center of rigidity R1 of the building frame 1 and is provided between the building frame 1 and the sub-frame 2.

By providing the building frame 1 with a pair of sub-frames 2, as described above, horizontal vibration input may cause twisting D in the building frame 1 around its center of rigidity R1.

When a torsion D occurs in the building frame 1, the vibration damping device 3, while supported by the lower part 1a of the building frame 1, suppresses the movement of the lower part 2b of the sub-frame 2, which is displaced by the torsion transmitted from the building frame 1, thereby effectively suppressing the torsion D of the building frame 1.

The arrangement of the vibration damping device 3 in the above-mentioned mounting area F is described below with reference to Figures 6 to 9.

Figure 6 is a schematic plan view illustrating the arrangement of a vibration damping device in a vibration control structure for a building frame according to this embodiment, and Figure 7 is a schematic plan view illustrating an example of the arrangement of a vibration damping device in an attachment area.

At the height position where the mounting area F of the vibration damping device 3 is set, the center of rigidity R1 in a plane along the ground surface E of the building frame 1 and the centers of rigidity R2, R2 of the pair of sub-frames 2, 2 in a plane along the same ground surface E as the ground G on which the building frame 1 is constructed are both arranged on a straight line L.

In other words, the rigidity centers R2, R2 of the pair of sub-frames 2, 2 are both arranged on a straight line L that passes through the rigidity center R1 of the building frame 1.

For this reason, a pair of sub-frames 2, 2 are constructed on both sides of the building frame 1 so that their rigidity centers R2, R2 are positioned side by side on a straight line L passing through the rigidity center R1 of the building frame 1.

In the mounting area F of the vibration damping device 3 set in the gap S, the vibration damping devices 3 are first arranged in pairs on both sides of the straight line L that passes through the center of rigidity R1 of the building frame 1 and the centers of rigidity R2, R2 of a pair of sub-frames 2, 2 (see Figure 7).

As long as there is a pair of vibration damping devices 3 in relation to the above-mentioned straight line L, there is no limit to the number of devices that can be installed.

Therefore, a pair of vibration damping devices 3 are arranged for each of the sub-frames 2, 2, on one side and the other side of each of the centers of rigidity R2, R2, which are separated by the straight line L.

Secondly, the arrangement of these vibration damping devices 3 is set by a tangent Tn (n is a natural number) that is drawn from the center of rigidity R2, R2 of each sub-frame 2, 2 toward a circle Cn (n is a natural number) that is drawn with the center of rigidity R1 (center of torsion D) of the building frame 1 as its center.

A pair of tangents Tn from the center of rigidity R2 of the secondary frame 2 is drawn on both sides separated by the straight line L.

Multiple circles Cn can be drawn with different radii centered on the rigidity center R1 of the building frame 1, and multiple tangents Tn are taken from the rigidity center R2 of the sub-frame 2 so as to be tangent to each of these multiple circles Cn.

A pair of vibration damping devices 3, 3 arranged on both sides of the straight line L are oriented so that the vibration damping effect occurs in the direction of the tangent line Tn that touches the circle Cn.

It does not matter which tangent Tn of which circle Cn it is, it is placed in the direction of any tangent Tn of any circle Cn.

Of the multiple circles Cn around the center of rigidity R1 of the building frame 1, the displacement of the torsion D of the top 1b of the building frame 1 is maximum along the outermost circle with the largest radius (hereinafter also referred to as the maximum circle) Cn. Therefore, it is desirable that the vibration damping device 3 connected to the lower part 2b of the sub-frame 2 to which the torsion D is directly transmitted from the top 1b of the building frame 1 is oriented so that the vibration damping effect (torsion suppression effect) occurs toward the tangent Tn from the center of rigidity R2 of the sub-frame 2 that is tangent to this maximum circle Cn, as far as the vibration damping device 3 can be installed in the mounting area F, so that the torsion D can be effectively suppressed.

In the case of an oil damper that performs the above-mentioned expansion and contraction motion to damp vibrations, the direction of the expansion and contraction motion is directed in the tangent direction Tn from the center of rigidity R2 of the secondary structure 2 to the maximum circle Cn.

As shown in FIG. 7, in terms of the arrangement, the vibration damping device 3 is horizontal with respect to the ground surface E as long as one end 3a can be connected to the building frame 1 and the other end 3b can be connected to the sub-frame 2 within the mounting area F of the vibration damping device 3 set in the gap S, and is in a diagonal relationship with respect to the line L, with the distance from the line L being short at the other end 2b on the sub-frame 2 side and long at the one end 3a on the building frame 1 side. It is desirable that the pair of vibration damping devices 3, 3 on each sub-frame 2 are arranged in a V-shape in plan view, with the one ends 3a spaced apart from each other on the building frame 1 side and the other ends 3b approaching each other on the sub-frame 2 side.

The vibration damping device 3 arranged in this manner will of course produce a vibration damping effect and provide vibration control when a component force of the vibration force is input, regardless of the type of vibration that occurs between the building frame 1 and the sub-frame 2.

In short, the vibration damping device 3 provided between each sub-frame 2 and the building frame 1 is arranged so that at least one of the tangents Tn to one of the circles Cn centered on the rigidity center R1 of the building frame 1 generates a vibration damping effect in a direction passing through the rigidity center R2 of the sub-frame 2. As a result, the vibration damping device 3 efficiently damps the vibration of the building frame 1 caused by horizontal vibration input through the integrated vibration system described above, while at the same time effectively suppressing the twist D that occurs in the building frame 1.

The action of the vibration control structure of the building frame according to this embodiment will be explained. When a horizontal vibration external force such as an earthquake motion is generated on the ground G and this vibration external force is input to the building frame 1, the top 1b of the building frame 1 and the top 2a of the sub-frame 2 are rigidly connected, so that the lower part 1a of the building frame 1 fixed to the ground G is the fixed end, and the lower parts 2b of the pair of sub-frames 2 provided on both sides of the building frame 1 are the free ends, and vibration is generated in the integrated vibration system shown in FIG. 5. In addition, when a vibration control effect is acting on the building frame 1, a twist D is generated around the rigid center R1 of the building frame 1.

The vibration damping device 3 provided in each gap S between the lower part 1a of the building frame 1 and the lower parts 2b of the pair of sub-frames 2 can dampen the building frame 1 against vibration input, with the sub-frames 2 acting as mass elements and the vibration damping device 3 acting as damping elements, while the building frame 1 acts as a spring element. Furthermore, by arranging the vibration damping device 3 around the rigidity center R1 of the building frame 1, the vibration damping device 3 can also suppress the twisting D of the building frame 1.

Regarding the suppression of torsion D, in more detail, when torsion D occurring at the top 1b of the building frame 1 is transmitted to the sub-frame 2 via a rigid joint, and the lower part 2b of the sub-frame 2 is displaced relative to the lower part 1a of the building frame 1, a torsional force from the building frame 1 acts on each of the pair of vibration damping devices 3 of each sub-frame 2 along the tangent Tn of the circle Cn around the rigid center R1 of the building frame 1, and a compressive force is input to one of the pair of vibration damping devices 3, 3, and a tensile force is input to the other, thereby damping the torsional force.

In this way, force can be applied to the vibration damping device 3 in the direction of the twist D (tangential direction), effectively suppressing the twist D that occurs in the building frame 1.

The torsional deformation occurring in the building frame 1 is most pronounced in the lower part 2b of the sub-frame 2, which is the free end. Therefore, by connecting the lower part 2b of the sub-frame 2, where deformation is most pronounced, to the lower part 1a of the building frame 1 via a vibration damping device 3, the torsion D occurring in the building frame 1 can be efficiently and effectively suppressed.

In particular, if the vibration damping device 3 is positioned so that the vibration damping action occurs along the tangent line Tn from the center of rigidity R2 of the sub-frame 2, which is tangent to the above-mentioned maximum circle Cn where the displacement of the torsion D of the building frame 1 is maximum, the torsion D occurring in the building frame 1 can be suppressed most effectively and efficiently.

Furthermore, when the torsional phase between the lower part 1a of the building frame 1, which is the fixed end of the integrated vibration system, and the lower part 2b of the sub-frame 2, which is the free end, is in opposite phase, the maximum relative torsional displacement is input to the vibration damping device 3 arranged along the tangent Tn of the maximum circle Cn, and the maximum torsional suppression effect can be achieved.

The vibration damping device 3 arranged in this manner can suppress torsion D, and also damp the vibration of the building frame 1 by damping the component forces of the horizontal vibration input that vibrates the building frame 1 as described above.

Figures 8 and 9 are explanatory diagrams that explain the case where the center of rigidity R1 of the building frame 1 is offset from the centroid X in a plane along the ground surface E of the building frame 1.

In Figure 6, the center of rigidity R1 of the building frame 1 coincides with the centroid, but there are cases where these are misaligned.

Figure 8 shows a case where, on the straight line L along the longitudinal direction of the building frame 1, the distance (La) from the center of rigidity R2 of one sub-frame 2 to the center of rigidity R1 of the building frame 1 is close, and the distance (Lb) from the center of rigidity R2 of the other sub-frame 2 to the center of rigidity R1 of the building frame 1 is far.

In each sub-frame 2, 2, the pair of vibration damping devices 3, 3 are arranged in a V-shape, as described above, at an angle to the straight line L, and the relationship between the damping performance Fa of the vibration damping device 3 connected to one sub-frame 2 and the damping performance Fb of the vibration damping device 3 connected to the other sub-frame 2 is set to La x Fb = Lb x Fa.

Figure 9 shows the case of an anisotropic building in which the center of rigidity R1 of the building frame 1 is shifted in the width direction and length direction from the center of rigidity R0 due to an overhanging portion 1c (center of rigidity Rc) or the like.

Even in this case, the sub-frames 2, 2 are arranged relative to the building frame 1 so that, with respect to the rigidity center R1 of the anisotropic building frame 1, the rigidity centers R2, R2 of the pair of sub-frames 2, 2 in a plane along the ground surface E are both arranged on a straight line L passing through the rigidity center R1 of the building frame 1, and based on the distance (La) from the rigidity center R2 of one sub-frame 2 to the rigidity center R1 of the building frame 1 on the straight line L and the distance (Lb) from the rigidity center R2 of the other sub-frame 2 to the rigidity center R1 of the building frame 1, the relationship between the damping performance Fa of the vibration damping device 3 connected to one sub-frame 2 and the damping performance Fb of the vibration damping device 3 connected to the other sub-frame 2 is set to La x Fb = Lb x Fa.

In other words, although the position of the center of rigidity R1 of the building frame 1 varies, if the dimensions and weight of a pair of sub-frames 2, 2 are the same, and the centers of rigidity R2, R2 of these sub-frames 2 in a plane along the ground surface E are both arranged on a straight line L passing through the center of rigidity R1 of the building frame 1, the damping performance of the vibration damping device 3 of one sub-frame 2 can be set in a well-balanced manner by multiplying the damping performance of the vibration damping device 3 of the other sub-frame 2 by the ratio of the distance between the center of rigidity R1 of the building frame 1 and the center of rigidity R2 of each sub-frame 2, and twisting caused by imbalances in the frame arrangement, etc. can be effectively suppressed.

In the vibration control structure of the building frame of this embodiment, a pair of sub-frames 2, 2 are rigidly connected to the top 1b of the building frame 1 at only the top 2a of the sub-frame 2, as shown in Figure 1, so that each of the sub-frames 2 is suspended and supported from the top 1b of the building frame 1.

The top 1b of the building frame 1, which is rigidly connected to the top 2a of the sub-frame 2, is set to have a higher rigidity than the other parts of the building frame 1 other than the top 1a, as shown by the hatched area J in Figure 1, as necessary, so that it can withstand the suspension support of the sub-frame 2.

The rigidity of the top 1b of the building frame 1, which can suspend and support the sub-frame 2, can be increased by using well-known rigidity-enhancing measures, such as increasing the amount of steel in the column-beam frame that constitutes the top 1b, or, if the building frame 1 is made of reinforced concrete, making only the top 1b out of steel reinforced concrete.

In addition, rather than uniformly increasing the rigidity of the entire top 1b of the building frame 1, it is of course also possible to set the rigidity high only around the area where the rigid joint is performed, as shown by the hatched area K in Figure 3.

1 Building frame 1a Lower part of building frame 1b Top part of building frame 2 Sub-frame 2a Top part of sub-frame 2b Lower part of sub-frame 3 Vibration damping device 3a One end of vibration damping device 3b Other end of vibration damping device Cn Circle centered on the rigidity center of building frame D Torsion E Ground surface Fa Damping performance of vibration damping device connected to one sub-frame Fb Damping performance of vibration damping device connected to the other sub-frame G Ground J, K Area where the rigidity of the building frame is set high L Straight line passing through each rigidity center of a pair of sub-frames and the rigidity center of the building frame La Distance from the rigidity center of one sub-frame to the rigidity center of the building frame Lb Distance from the rigidity center of the other sub-frame to the rigidity center of the building frame R1 Rigidity center of building frame R2 Rigidity center of sub-frame S Gap Tn Tangent to a circle that passes through the center of rigidity of the secondary frame

Claims (3)

A vibration control structure for controlling vibration input of a building frame constructed with its lower part fixed to the ground,
a pair of sub-frames are provided on both sides of the building frame along the height direction of the building frame, the tops of the sub-frames are rigidly connected to the top of the building frame, and the bottoms of the sub-frames are spaced apart above the ground to form an integrated vibration system with the building frame;
Each of these sub-frames is suspended from the top of the building frame,
The rigidity of the top of the building frame is set to be higher than that of other parts of the building frame,
A vibration damping device is provided in each gap between the lower part of each of these sub-frames and the lower part of the building frame, the vibration damping device being arranged in a direction along the rigid center of the building frame in a plane along the ground surface, with one end connected to the building frame and the other end connected to the sub-frame ,
A vibration control structure for a building frame, characterized in that the area around the top of the building frame where the sub-frame is rigidly connected is set to have higher rigidity than other areas . The rigidity centers of the pair of sub-frames in a plane along the ground surface are both arranged on a straight line passing through the rigidity center of the building frame,
The vibration damping device is arranged in a pair on both sides of the straight line passing through the rigidity center of the building frame, and the arrangement of these vibration damping devices is oriented so that a vibration damping effect occurs in at least a direction in which a tangent to a circle centered on the rigidity center of the building frame passes through the rigidity centers of a pair of sub-frames. The vibration damping structure described in claim 2, characterized in that when the distance from the rigidity center of one of the sub-frames to the rigidity center of the building frame is La and the distance from the rigidity center of the other sub-frame to the rigidity center of the building frame is Lb, the damping performance Fa of the vibration damping device connected to one of the sub-frames and the damping performance Fb of the vibration damping device connected to the other sub-frame are set to a relationship of La x Fb = Lb x Fa.