# Patent

## Title
Damping intermediate pillar and damping structure using the same

## Abstract

A damping intermediate pillar, which can exhibit a sufficient resistance against the horizontal force of a strong earthquake by reinforcing the joins between the damping intermediate pillar and the upper and lower beams, is disclosed. A damping intermediate pillar 14, used for a building or a structure configured of pillars 1 and beams 3, is divided into upper and lower damping intermediate pillar portions 14a, 14b of H shape steel, and includes a plurality of inner steel plates 7b fixed on the damping intermediate pillar portion 14b and a plurality of outer steel plates 7a fixed on the other damping intermediate pillar portion 14a. The inner and outer steel plates are arranged alternately in a single or a plurality of layers, between which a viscoelastic member 15 is held to make up a viscoelastic damper 17. The coupling end surfaces of the intermediate pillar portions 14a, 14b directed vertically are fixed on the upper and lower floor beams 3a, 3b. Further, one or both sides of each of the damping intermediate pillar portions 14a, 14b (i.e. the coupling members 13a, 13b) and the upper and lower floor beams 3a, 3b are coupled to each other by knee braces 19.

## Background
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a damping intermediate pillar and a damping structure using such a damping pillar intended to absorb an input vibration energy or, especially, a horizontal force in framed structures and various other structures of buildings.
2. Description of the Related Art
The conventional techniques in this category include the following (1) to (7):
(1) Japanese Unexamined Patent Publication No. 2000-274108 relating to a structure of a viscoelastic damper coupled directly to the beams of upper and lower floors, (2) Japanese Unexamined Patent Publication No. 2000-54680 relating to a detailed structure for installing a viscoelastic damper on the beams of upper and lower floors, (3) Japanese Unexamined Patent Publication No. 2000-73605 relating to the surface shape of a laminated steel plate for a viscoelastic damper, (4) Japanese Unexamined Patent Publication No. 2000-73608 relating to a technique for coupling a viscoelastic damper, (5) Japanese Unexamined Patent Publication No. 2000-73609 relating to a technique for coupling a viscoelastic damper, (6) Japanese Unexamined Patent Publication No. 2000-73610 relating to a technique for coupling a viscoelastic damper, and (7) Japanese Unexamined Patent Publication No. 2000-73611 relating to the reinforcement around a viscoelastic damper.
Of the conventional techniques described above, an explanation will be given of a case in which the horizontal vibrations acting on the beams of the upper and lower floors are attenuated by being transmitted to a viscoelastic damper through an intermediate pillar, with reference to FIGS. 23A and 23B. In FIGS. 23A and 23B, beams 3a, 3b of the upper and lower floors and pillars 1 are coupled to each other by pillar-beam joins 2, and the beams 3a, 3b of the upper and lower floors are coupled to each other by a damping intermediate pillar 4 having a viscoelastic damper 6 at an intermediate portion thereof, thereby making up a structural frame of a building.
Specifically, the damping intermediate pillar 4 is divided into upper and lower portions, i.e. an upper damping intermediate pillar portion 4a with the upper end thereof fixed to the beam 3a of the upper floor and a lower damping intermediate pillar portion 4b with the lower end thereof fixed to the beam 3b of the lower floor. Also, the upper and lower damping intermediate pillars portion 4a, 4b are fixed with inner and outer steel plates 5a, 5b, respectively, which are superposed one on the other in spaced parallel relation to each other. A tabular viscoelastic member 5 of a predetermined thickness is arranged in the space between the superposed parallel steel plates 5a, 5b for holding the upper and lower damping intermediate pillars 4a, 4b. The tabular viscoelastic member 5 is held and fixed by adhesive thereby to make up a viscoelastic damper 6.
Assume that the structural frame of a building having the damping intermediate pillar 4 described above vibrates in an earthquake and a horizontal force is applied to the beams 3a, 3b in the direction of arrow in FIG. 23B. The particular horizontal force is transmitted to the viscoelastic member 5 from the beams 3 through the upper and lower damping intermediate pillar portions 4a, 4b. The horizontal force is attenuated by the viscoelastic member 5, while the pillars 1, the upper and lower beams 3a, 3b and the damping intermediate pillar 4 are deformed as indicated by dotted lines in FIG. 23B. In this way, the vibration is attenuated gradually.
In the case where a structural frame of a building is designed with a viscoelastic damper built in an intermediate pillar, the horizontal force due to an earthquake of an assumed predetermined magnitude and the damping capacity of the building are determined by calculations. In a manner to meet this condition, a viscoelastic damper having an attenuation capacity of a predetermined value determined by the material, size and thickness (sectional area) of the viscoelastic member is fabricated and built in the intermediate pillar. The conventional join structure between the upper and lower end portions of the damping intermediate pillar and the upper and lower floor beams, however, poses the following problem as it lacks the strength of endurance of the join between the damping intermediate pillar 4 and the upper and lower floor beams 3a, 3b against the horizontal force which may be exerted by an earthquake.
Specifically, in FIG. 23B, the damping action of the viscoelastic damper 6 is transmitted from the damping intermediate pillar 4 via the beams 3a, 3b to the pillar-beam joins 2 to damp the vibration of the building. In view of the fact that the upper and lower end portions of the damping intermediate pillar 4 are fixedly coupled simply by bolts or welding to the beams 3a, 3b of the upper and lower floors, however, the join strength is not sufficient against an earthquake of a comparatively large magnitude. As a result, the joins 9a between the damping intermediate pillar 4 and the beams 3 are inconveniently liable be broken before the damping function is exhibited.
The object of the present invention is to provide a novel damping intermediate pillar and a damping structure employing such a damping intermediate pillar which solve the problem of the prior art described above.
SUMMARY OF THE INVENTION
The invention has been developed to solve the problem described above, and the gist thereof is as follows:
(1) A damping intermediate pillar for a structure having pillars and beams, comprising upper and lower damping intermediate pillar portions of H shape steel directed upward and downward, respectively, a plurality of inner steel plates fixed on one of the damping intermediate pillar portions, a plurality of outer steel plates fixed on the other damping intermediate pillar portion, the inner steel plates and the outer steel plates being arranged alternately with each other in a single layer or a plurality of layers, a viscoelastic member held between the inner and outer steel plates thereby to make up a vibration energy absorbing unit, a plurality of coupling members of H shape steel coupled to each of the upper and lower damping intermediate pillar portions directed upward and downward, respectively, the coupling members being fixed on the beams of the upper and lower floors, respectively, and a plurality of knee braces, wherein one or both sides of the upper and lower damping intermediate pillar portions or the coupling members of H shape steel are coupled to the upper and lower floor beams, respectively, by the knee braces.
(2) A damping intermediate pillar for a structure having pillars and beams, comprising upper and lower damping intermediate pillar portions of H shape steel directed upward and downward, respectively, the lower damping intermediate pillar portion making up a damping box containing a viscous material and having an upper opening, the upper damping intermediate pillar portion being formed of a steel member inserted into the viscous material of the damping box thereby to make up a vibration energy absorbing unit, a plurality of coupling members of H shape steel coupled to the upper and lower damping intermediate pillar portions directed upward and downward, respectively, the coupling members being fixed on the beams of the upper and lower floors, respectively, and a plurality of knee braces, wherein one or both sides of the upper and lower damping intermediate pillar portions or the coupling members of H shape steel are coupled to the upper and lower floor beams, respectively, by the knee braces.
(3) A damping intermediate pillar, wherein the knee braces described in (1) or (2) are replaced by a plurality of reinforcing ribs, one or both sides of the intermediate pillar and one side of each of the reinforcing ribs are fixed to each other, and the other side of each of the reinforcing ribs and the beams of the upper and lower floors are fixed to each other.
(4) A damping intermediate pillar as described in (1) or (2), wherein the knee braces are replaced by a plurality of reinforcing ribs, one side of each of the reinforcing ribs and the flange of the corresponding one of the coupling members of H shape steel are fixed to each other, and the other side of each of the reinforcing ribs and the corresponding beam flange of the upper and lower floors are fixed to each other.
(5) A damping structure, comprising a plurality of damping intermediate pillars between adjacent pillars according to any one of (1) to (4).
According to this invention, in addition to the joins for fixing a damping intermediate pillar by welding or bolting to the beams of the upper and lower floors, knee braces or reinforcing ribs are used to couple one or both sides of the damping intermediate pillar or the coupling members to the beams of the upper and lower floors, thereby improving the strength of the joins, as a whole, between the damping intermediate pillar and the beams. Therefore, a sufficient resistance can be exhibited, with comparative ease, against a large horizontal force acting on a building at the time of an earthquake of a large magnitude. Also, the use of the knee braces or the reinforcing ribs for coupling increases the shearing deformation of the viscoelastic material, thereby making it possible to absorb a larger amount of vibration energy.



BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1A is a schematic diagram showing a structural arrangement of a damping intermediate pillar according to an embodiment of the invention.
FIG. 1B is a diagram for explaining the attenuation effect of the structural frame of a building having a damping intermediate pillar according to a first embodiment at the time of an earthquake.
FIG. 2 is an enlarged front view of the damping intermediate pillar shown in FIG. 1.
FIG. 3 is a sectional view taken in line A—A in FIG. 2.
FIG. 4 is an enlarged sectional view of a viscoelastic damper shown in FIG. 3.
FIG. 5A is a sectional view showing an example of the sectional shape of a knee brace.
FIG. 5B is a sectional view showing another example of the sectional shape of a knee brace.
FIG. 5C is a sectional view showing still another example of the sectional shape of a knee brace.
FIG. 5D is a sectional view showing yet another example of the sectional shape of a knee brace.
FIG. 5E is a sectional view showing a further example of the sectional shape of a knee brace.
FIG. 6 is a diagram showing in detailed a structural arrangement of a damping intermediate pillar according to a second embodiment of the invention.
FIG. 7 is a sectional view taken in line B—B in FIG. 6.
FIG. 8 is a diagram showing in detail a structural arrangement of a damping intermediate pillar according to a third embodiment of the invention.
FIG. 9 is a diagram showing in detail a structural arrangement of a damping intermediate pillar according to a fourth embodiment of the invention.
FIG. 10 is a diagram showing in detail a structural arrangement of a damping intermediate pillar according to a fifth embodiment of the invention.
FIG. 11 is a diagram showing in detail a structural arrangement of a damping intermediate pillar according to a sixth embodiment of the invention.
FIG. 12 is a diagram showing in detail a structural arrangement of a damping intermediate pillar according to a seventh embodiment of the invention.
FIG. 13 is a diagram showing in detail a structural arrangement of a damping intermediate pillar according to an eighth embodiment of the invention.
FIG. 14 is a sectional view taken in line C—C in FIG. 13.
FIG. 15 is a diagram showing in detail a structural arrangement of a damping intermediate pillar according to a ninth embodiment of the invention.
FIG. 16 is a sectional view taken in line D—D in FIG. 15.
FIG. 17 is a diagram showing in detail a structural arrangement of a damping intermediate pillar according to a tenth embodiment of the invention.
FIG. 18 is a sectional view taken in line E—E in FIG. 17.
FIG. 19A is a front view showing a structural arrangement of a damping intermediate pillar according to an 11th embodiment of the invention.
FIG. 19B is a side view showing a structural arrangement of a damping intermediate pillar according to the 11th embodiment of the invention.
FIG. 19C is a partially enlarged view of FIG. 19B.
FIG. 19D is a partially enlarged view of FIG. 19B.
FIG. 20 is a diagram for explaining the relation between the shearing force and the temperature of a damping intermediate pillar according to the invention.
FIG. 21 is a diagram for explaining the relation between the ratio of the rigidity (Kc) to the rigidity (Kd) of the viscoelastic damper and the temperature according to the invention.
FIG. 22 is a diagram for explaining the relation between the attenuation coefficient of a damping intermediate pillar and the temperature according to the invention.
FIG. 23A is a schematic diagram showing a structural arrangement of a damping intermediate pillar with a viscoelastic damper built therein according to the prior art.
FIG. 23B is a diagram for explaining the attenuation effect of the structural frame of a building having a conventional damping intermediate pillar with a viscoelastic damper built therein at the time of an earthquake.



DESCRIPTION OF THE PREFERRED EMBODIMENTS
Embodiments of the invention will be explained in detail below with reference to the accompanying drawings.
FIGS. 1 to 4 show a first embodiment of the invention, in which FIGS. 1A and 1B, corresponding to FIGS. 23A and 23B for explaining the prior art, are diagrams schematically showing the structural arrangement of a damping intermediate pillar having a viscoelastic damper built therein for explaining the attenuation effect of the structural frame of a building.
In FIG. 1, the structural frame of the building includes a pillar 1 of a rectangular steel pipe filled with concrete and beams 3 of H shape steel coupled to each other by pillar-beam joins 2. The structure also includes a damping intermediate pillar 14 having a viscoelastic damper 17 arranged between the beams 3a and 3b of the upper and lower floors. The structure for fixing the damping intermediate pillar 14 and the beams 3 is different from that of the prior art.
FIGS. 2 to 4 show a detailed structure of the first embodiment, in which FIG. 2 is an enlarged front view showing the manner in which the viscoelastic damper is mounted, FIG. 3 a sectional view taken in line A—A in FIG. 2, and FIG. 4 an enlarged view of the mounting portion of the viscoelastic damper.
In each of the drawings, the damping intermediate pillar 14 of H steel is segmented into an upper damping intermediate pillar portion 14a and a lower damping intermediate pillar portion 14b. Coupling plates 27 are fixed to the outer ends (the end portions in opposed relation to coupling members 13) of the upper damping intermediate pillar 14a and the lower damping intermediate pillar 14b, respectively. Coupling plates 27 fixed to the inner ends (the end portions in opposed relation to the damping intermediate pillar) of the upper and lower coupling members 13a, 13b are fixed to each other by fixing bolts 28, respectively. The coupling members 13a, 13b are formed of H shape steel and welded at a welding point 9 directly to the beams 3a, 3b of the upper and lower floors (the coupled portion is called the join 9a). As an alternative, an end coupling plate 11 is welded to the outer end (the end portions in opposed relation to the beam) of each of the coupling members 13a, 13b, and fixed by fixing bolts to the inner flanges 21 of the beams 3a, 3b of the upper and lower floors (not shown). On the longitudinal extension of the damping intermediate pillar 14, a reinforcing plate 8 is welded between the inner and outer flanges 21, 21a of the beams 3a, 3b of the upper and lower floors, respectively.
The configuration of the viscoelastic damper 17 is shown in the sectional view of FIG. 4. The forward ends 16 of the upper damping intermediate pillar portion 14a and the lower damping intermediate pillar portion 14b into which the damping intermediate pillar 14 is segmented are arranged in a closely spaced relationship with each other at the shown position. Inner and outer steel plates 7a, 7b are arranged in parallel to the web 22 of the damping intermediate pillar 14 and fixed by fixing bolts 18 in such a manner as to project from the forward ends on both sides of the web of the upper damping intermediate pillar portion 14a and the lower damping intermediate pillar portion 14b, respectively. The inner and outer steel plates 7a, 7b vertically arranged in opposite directions have the comb teeth thereof in mesh with each other through a plurality of gaps. A plurality of rectangular viscoelastic members 15 of a solid material 2.0 m2 in area and 5 mm thick, for example, are held in a plurality of the gaps formed between the inner and outer steel plates 7a, 7b, and have the side surfaces fixed on the side surfaces of the inner and outer steel plates 7a, 7b. The inner and outer steel plates 7a, 7b located at upper and lower positions, respectively, are arranged in alternate layers through the gaps. Thus, the inner steel plates 7b on the lower side are fixed through spacers 26a to both sides of the web of the lower damping intermediate pillar portion 14b, while the outer steel plates 7a on the upper side are fixed through spacers 26 to both sides of the web of the upper damping intermediate pillar portion 14a. 
The width of the rectangular viscoelastic members 15 and the inner and outer steel plates 7a, 7b is smaller than the distance between the flanges 10 on the two sides of the upper damping intermediate pillar portion 14a of H steel and, therefore, they can be accommodated between the flanges 10. The rectangular viscoelastic members 15 located inside are covered and protected by the outer steel plates 7a located on the outside. The outer steel plates 7a may be provided with stiffening plates 20.
According to the first embodiment of the invention, the coupling members 13a, 13b and the upper and lower floor beams 3a, 3b are coupled (at the joins 9a) directly to each other at the welding points 9 as described above or are fixed to each other by fixing bolts through the flanges not shown. In addition, the two sides of the coupling members 13a, 13b and the upper and lower floor beams 3a, 3b are coupled to each other by knee braces 19. As a result, the strength of the joins 9a between the damping intermediate pillar portions 14a, 14b and the upper and lower floor beams 3a, 3b is reinforced.
For the knee braces 19, any material can be employed such as a steel plate or a H shape steel member of a predetermined thickness having a buckling strength with a sectional structure shown in FIG. 5. Specifically, FIG. 5A shows a knee brace 19c of H shape steel, FIG. 5B a knee brace 19d of channel-shaped steel members coupled back to back, FIG. 5C a knee brace 19e of a rectangular steel member, FIG. 5D a knee brace 19f in the form of a steel pipe, and FIG. 5E a knee brace 19g of four angle-shaped steel members coupled back to back. The knee braces 19 shown in FIG. 2 have the same section as the knee brace 9d shown in FIG. 5B, and have the ends thereof fixed by fixing bolts 31 to the gusset plates 19a, 19b fixed on the flange 30 of the H shape steel coupling members 13a, 13b and the inner flanges 21 of the beams 3a, 3b. 
The operation of the first embodiment will be explained. According to the first embodiment, at the time of an earthquake, the horizontal force acting on the beams 3a, 3b at the upper and lower parts of the structural body is transmitted as a shearing force to and deforms the viscoelastic members 15 through the upper and lower damping intermediate pillar portions 14a, 14b. The vibration of the building is attenuated as the attenuation effect is transmitted from the viscoelastic members 15 via the upper and lower damping intermediate pillar portions 14a, 14b and the end portions of the beams 3a, 3b to the pillar-beam joins 2.
In the case where an excessive horizontal force of a strong earthquake is exerted on the building of the conventional structure, the attenuation effect is not exhibited by the viscoelastic member 15 because an excessive local shearing force acts on the joins 9a with the fixing bolts 12 (which may alternatively be a weld zone) between the damping intermediate pillar portions 14a, 14b (i.e. the coupling members 13a, 13b) and the beams 3a, 3b, thereby often shearing off the fixing bolts 12 (or breaking the weld zone, as the case may be) of the joins 9a. According to the first embodiment, in contrast, the stress acting on the joins between the coupling members 13a, 13b and the beams 3a, 3b is received by the knee braces 19 having a large buckling resistance, and therefore, the stress is not concentrated on the joins 9a with the fixing bolts 12 (or the weld zone), so that the attenuation effect is positively exhibited by the damping intermediate pillar portions 14a, 14b even when an earthquake of large magnitude occurs. In addition, the larger shearing deformation of the viscoelastic member 15 can absorb more vibration energy.
In the first embodiment, the knee braces 19 are arranged on both sides of the coupling members 13a, 13b, as shown. In the second embodiment, however, as shown in FIGS. 6 and 7, the knee braces 19 may be arranged only on the side of the coupling members 13a, 13b. As another alternative, as shown in FIG. 8 of the third embodiment, the knee braces 19 may be arranged only on the right side of the coupling members 13a, 13b. Further, as shown in FIG. 9 of the fourth embodiment, the left and right knee braces 19 may be arranged only for the upper coupling member 13a. As still another alternative, as shown in FIG. 10 of the fifth embodiment, the left and right knee braces 19 may be arranged only for the lower coupling member 13b. Also, as shown in FIG. 11 of the sixth embodiment, the left and right knee braces 19 may be arranged at a steeper angle than in the first embodiment shown in FIG. 2. Further, as shown in FIG. 12 as the seventh embodiment, the ends of the knee braces 19 may be fixed by welding 9 to the flanges 30 on both sides of the coupling members 13a, 13b, and the inner flanges 21 of the beams 3a, 3b of the upper and lower floors.
The knee braces 19 may alternatively be fixed, though not shown, to the flanges 10 of the damping intermediate pillar portions 14a, 14b instead of to the flanges 30 of the coupling members 13a, 13b. In this case, the length of each knee brace 19 increases with the change in the inclination angle of the knee braces 19. The coupling members 13a, 13b may be done without, in which case, the damping intermediate pillar portions 14a, 14b are lengthened with the end portions thereof fixed directly to the inner flanges 21 of the beams 3a, 3b of the upper and lower floors. Also in this case, the knee braces 19 are fixedly bolted to the flanges 10 of the upper and lower damping intermediate pillar portions 14a, 14b. 
As explained above, the knee braces are coupled to one or both sides of the upper and/or lower coupling members.
The knee braces may be coupled to one or both sides of the upper and/or lower intermediate pillar portions.
The knee braces are fixed to the corresponding beams of the upper and lower floors.
FIGS. 13 and 14 show an eighth embodiment. FIG. 13 is a front view showing the manner in which the damping intermediate pillar 14 is mounted, and FIG. 14 a sectional view taken in line C—C in FIG. 13. The eighth embodiment is different from the first to seventh embodiments in that the knee braces 19 are replaced by reinforcing ribs 23 in each of the embodiments described above. The reinforcing ribs 23 are each formed of a steel plate of a predetermined thickness in the shape of a right triangle, and include mounting plates 23a, 23b on the two sides forming the right angle. As shown in FIGS. 13, 14, the mounting plate 23a on one side of the reinforcing rib 23 is applied to the flange 30 of the coupling members 13a, 13b, and is coupled by fixing bolts 24. At the same time, the mounting plate 23b on the other side of each reinforcing rib 23 is applied to the inner flange 21 of the upper and lower beams 3a, 3b, and is fastened by fixing bolts 24. According to the eighth embodiment, the joins 9a between the upper and lower coupling members 13a, 13b and the inner flanges 21 of the upper and lower beams 3a, 3b are formed by welding as designated by 9. The remaining configuration is identical to that of the first embodiment and will not be explained.
FIGS. 15 and 16 show a ninth embodiment, in which FIG. 15 is a front view showing the manner in which the damping intermediate pillar 14 is mounted, and FIG. 16 is a sectional view taken in line D—D in FIG. 15. The ninth embodiment is different from the eighth embodiment in that an end coupling plate 11 is welded to the outer end of each of the coupling members 13a, 13b. This end coupling plate 11 is applied to the corresponding inner flange 21 of the upper and lower floor beams 3a, 3b of H shape steel. These members are coupled to each other by fixing bolts 12 inserted through nuts, thereby fixing the upper and lower damping intermediate pillar portions 14a, 14b to the upper and lower beams 3a, 3b, respectively. The other configuration is identical to that of the eighth embodiment and will not be explained.
Also in the eighth and ninth embodiments, the stress acting on the joins 9a between the coupling members 13a, 13b and the beams 3a, 3b is received by the reinforcing ribs 23 having a large buckling resistance. Therefore, the stress is not concentrated only on the joins 9a with the welding or the fixing bolts between the coupling member 13a, 13b and the beams 3a, 3b. In this way, the attenuation effect can be positively exhibited by the upper and lower damping intermediate pillar portions 14a, 14b even at the time of a strong earth quake. In addition, a greater amount of vibration energy can be absorbed.
FIGS. 17 and 18 show a tenth embodiment, in which FIG. 17 is a front view showing the manner in which damping intermediate pillars 14 are mounted, and FIG. 18 is a sectional view taken in line E—E in FIG. 17. The tenth embodiment is different from the first to ninth embodiments in that two damping intermediate pillars 14 are arranged at a small interval in the space formed by the upper and lower beams 3a, 3b and adjoining pillars 1. The reinforcing ribs 25 of a rectangular steel plate are arranged between the adjoining damping intermediate pillars 14, 14. The mounting plate 25a on one side of each of the reinforcing ribs 25 is coupled by a fixing bolt 29 to the flange 30 of the corresponding one of the coupling members 13a, 13b of the upper and lower damping intermediate pillar portions 14a, 14b, while the mounting plate 25b on the other side of the reinforcing rib 25 is coupled by a fixing bolt 29 to the inner flange 21 of the upper and lower beams 3a, 3b. As in the eighth and ninth embodiments, the outer flanges 30 (flanges closer to the adjoining pillar) of the coupling members 13a, 13b and the inner flanges 21 of the beams 3a, 3b are bolted to each other by the reinforcing ribs 23 in the shape of right angle, respectively.
As described above, according to the tenth embodiment, two (or a plurality of) damping intermediate pillars 14 are employed at the same time and summed up damping performance can be exhibited. As a result, the structural size of each damping intermediate pillar 14 can be reduced. This is more advantageous than a large damping intermediate pillar from the viewpoint of fabrication, transportation and construction. An especially great advantage is obtained in an application to a building having built therein a damping unit against an earthquake of large magnitude. Also in the tenth embodiment, the stress acting on the joins 9a between the coupling members 13a, 13b and the beams 3a, 3b is received by the reinforcing ribs 23, 25 having a large buckling resistance. Therefore, the stress is not concentrated only on the joins 9a with the melding or the fixing bolts between the coupling members 13a, 13b and the beams 3a, 3b. Thus, the damping intermediate pillar portions 14a, 14b can positively exhibit an attenuation effect even against a strong earthquake in the same manner as in the first to fourth embodiments.
FIG. 19 shows an 11th embodiment of the invention, in which FIG. 19A is a front view showing the manner in which a damping intermediate pillar is mounted, FIG. 19B a side view thereof, and FIGS. 19C and 19D partially enlarged views of FIG. 19B. According to the 11th embodiment, the viscoelastic damper 17 is formed of a semi-liquid viscous material 33 instead of the solid viscoelastic member 15 in the first to tenth embodiments. Specifically, in the 11th embodiment, the semi-liquid viscous material 33 is filled in a damping box 32 doubling as the lower damping intermediate pillar portion 14b. In the semi-liquid viscous material 33, a damping steel member 34 doubling as the upper damping intermediate pillar portion 14a is inserted from above in a way movable in horizontal direction, thereby making up the damping intermediate pillar 14.
The damping box 32 is flat and rectangular in shape and, at an open upper end, has a reinforcing flange 36 fixed thereto. A bottom plate 35 of the damping box 32 is fixed by fixing bolts 37 to the inner flange 21 of the lower beam 3b. The mounting plate 38 fixed at the upper end of the damping steel member 34, on the other hand, is fixed by fixing bolts 37 to the inner flange 21 of the upper beam 3a. Further, according to the 11th embodiment, the sides of the upper and lower damping intermediate pillar portions 14a, 14b and the upper and lower beams 3a, 3b are coupled to each other by reinforcing ribs 23 in the shape of right triangle, in the same way as in the fourth and eighth embodiments. In the 11th embodiment, the reinforcing ribs 23 may be replaced by knee braces 19 (not shown) as in the first and second embodiments. The other configuration is similar to that of the eighth and ninth embodiments.
Also in the configuration of the 11th embodiment, when a horizontal fore acts on the beams 3 at the time of an earthquake, the damping effect is exhibited by the horizontal movement of the damping steel member 34 against the resistance of the semi-liquid viscous material 33 in the damping box 32 at the ends of the beams 3.
According to the embodiments of the invention, if an external force of an earthquake or the like having a frequency f of 0.5 Hz has been applied, Kd is the rigidity of the viscoelastic damper (vibration energy absorber) 17, and Kc is the rigidity of the integrated member including the damping intermediate pillar portions 14a, 14b, the coupling members 13a, 13b, the beams 3a, 3b and the knee braces 19 (or the reinforcing ribs 23) coupled in series then FIG. 20 shows the maximum shearing force of the damping intermediate pillar 14 associated with the value Kc/Kd of 0.5 to 4 at the temperature of 20° C. as shown in FIG. 21. FIG. 22 shows the attenuation coefficient of the viscoelastic damper 17 taking into consideration the rigidity of the damping intermediate pillar portions 14a, 14b, the coupling members 13a, 13b, the beams 3a, 3b and the knee braces 19 (or the reinforcing ribs 23).
FIG. 20 shows the shearing force of the damping intermediate pillar 14 with the change in the serial spring rigidity Kc of the serially-connected members. The ratio Kc/Kd for five different serial spring rigidities Kc are shown. They include Kc=Rigid (Kc/Kd=∞), Kc=145 KN/mm (Kc/Kd=3.73), Kc=108 KN/mm (Kc/Kd=2.72), Kc=73 KN/mm (Kc/Kd=1.76) and Kc=36 KN/mm (Kc/Kd=0.8). Kc=Rigid (Kc/Kd=∞) indicates the case in which the serial spring rigidity Kc is very high, and represents the case in which the viscoelastic damper 17 is coupled directly to the pillar-beam joins 2 of the structure. The portions subjected to the inter-layer displacement in FIG. 20 are as shown in FIG. 1. Also, the ratio Kc/Kd is associated with the temperature of 20° C. of the viscoelastic material. FIG. 20 indicates that an increased value of the serial spring rigidity Kc increases the shearing force, i.e. the attenuation effect of the damping intermediate pillar 14. As described above, the attenuation performance of the damping intermediate pillar 14 is considerably affected by the serial spring rigidity Kc. By mounting the knee braces 19 or the reinforcing ribs 23, the serial spring rigidity Kc can be easily improved, thereby effectively producing a higher attenuation performance. Also, since the knee braces 19 or the reinforcing ribs 23 can be mounted very easily, the working procedure is very simple and results in a lower cost.
FIG. 22 shows the attenuation coefficient of the damping intermediate pillar 14 with the change in the serial spring rigidity Kc. It can be seen that an even more effective attenuation performance can be achieved by increasing the serial spring rigidity Kc, as in the case of the shearing force. This can be realized with comparative ease by the provision of the knee braces 19 or the reinforcing ribs 23.
The damping intermediate pillar 14 according to the embodiments of the invention can easily produce a higher attenuation performance in combination with the knee braces 19 or the reinforcing ribs 23. At the same time, the joins between the damping intermediate pillar 14 and the beams 13 are reinforced, thereby realizing an economical damping intermediate pillar 14 which is low in cost.
It will thus be understood from the foregoing description that, according to the invention, the coupling end portions of the damping intermediate pillar are fixed to the beams of the upper and lower floors on the one hand and one or both sides of the damping intermediate pillar are coupled with the upper and lower floor beams using knee braces or reinforcing ribs. As a result, the coupling strength of the joins between the damping intermediate pillar and the beams is improved. Thus, a sufficient strength is exhibited against the horizontal force of a strong earthquake, thereby obviating the problem of the conventional structure in which the joins between the damping intermediate pillar and the beams is broken before the damping function is fully exhibited. Also, the improved serial spring rigidity can produce a larger vibration attenuation ability.

## Claims

1. A structural frame for a building comprising:
an upper horizontal floor beam and a lower horizontal floor beam located below said upper horizontal floor beam;
a first vertical pillar coupled to said upper horizontal floor beam and said lower horizontal floor beam;
a second vertical pillar horizontally spaced from said first vertical pillar, with said second vertical pillar coupled to said upper horizontal floor beam and said lower horizontal floor beam;
a damping intermediate pillar located between said first vertical pillar and said second vertical pillar, said damping intermediate pillar comprising:
an upper damping intermediate pillar portion of H shape steel directed upward toward said upper horizontal floor beam and a lower damping intermediate pillar portion of H shape steel directed downward toward said lower horizontal floor beam;
a plurality of inner steel plates fixed on one of the damping intermediate pillar portions;
a plurality of outer steel plates fixed on the other damping intermediate pillar portion;
said inner steel plates and said outer steel plates being arranged alternately with each other in a single layer or a plurality of layers, with said inner steel plates and said outer steel plates being parallel to one another;
a viscoelastic member held between the inner and outer steel plates thereby to make up a vibration energy absorbing unit;
a coupling member of H shape steel coupled to each of said upper and lower damping intermediate pillar portions directed upward and downward, respectively, said coupling members being fixed on the upper and lower horizontal floor beams, respectively; and
a plurality of knee braces, wherein one or both sides of the coupling members of H shape steel are coupled to the upper and lower horizontal floor beams, respectively, by said knee braces.

2. A structural frame according to claim 1, wherein said knee braces are reinforcing ribs, one side of each of said reinforcing ribs is fixed to a flange of a corresponding one of said coupling members of H shape steel, and the other side of each of said reinforcing ribs is fixed to a corresponding beam flange of the upper and lower horizontal floor beams.

3. A structural frame comprising a plurality of damping intermediate pillars according to claim 1 located between said first vertical pillar and said second vertical pillar.