CN1061407C - Stiffness decoupler for base insolation of structures - Google Patents

Abstract

A stiffness isolation device for protecting a building or other architectural structure (20) subject to earthquakes from collapse or catastrophic failure of such a structure (20). A preferred isolator (22) comprises long, relatively flexible, concrete-filled pipes (28) secured to the structure (20) and extending downwardly toward the underlying foundation (26), at least some of which are in contact with The foundations are connected to prevent the structure (20) from tipping over. The main bearing column (46) is supported on the foundation (26) and accommodates a group of pipe fittings, and a support device (32) is installed between the upper end of the column and the structure, which can make limited lateral movement therebetween.

Description

Rigidity isolation device separating base of building structure

In general terms, the present invention relates to stiffness isolation or shock absorbing devices for use in the construction of earthquake resistant structures such as multistory buildings or bridges. This arrangement effectively isolates the lateral stiffness of the structure involved from the load-bearing strength of the structure's supporting column system, or eliminates the interaction between lateral stiffness and load-bearing strength. In this way, the dynamic characteristics or changes of the structure under the seismic state can be effectively controlled, while maintaining the necessary bearing strength, vibration damping strength and natural period of the structure. The isolation device of the present invention preferably comprises several long, concrete-filled pipes fixed to the structure, and a main load-bearing column surrounding the pipes, which is located between the underlying foundation and the structure and holds the pipe fittings. A low-friction support is provided between the column and the structure to allow relative lateral movement therebetween.

Architects and structural engineers have long struggled with the design of buildings, bridges or other structures in areas prone to earthquakes. The recent earthquake in San Francisco is one example of the potentially catastrophic consequences of poorly designed buildings in such an area.

Numerous proposals have been made in the past aimed at increasing the seismic safety of various structures. In general, most contemporary proposals or solutions attempt to combine the qualities of strength (ie the ability to withstand large forces while maintaining elasticity), deformability and energy absorption. For example, it is known to support an extendable reinforced concrete frame structure using large elastic bearings to isolate the structure from the underlying foundation. But such mounts are expensive and some are subject to environmental damage.

Flexible steel energy absorbing devices have also been proposed in the past, which are rigid under operational loads but bend to absorb energy under large seismic loads. This solution depends on the hysteretic energy absorption capacity of the steel rods used as base isolation means.

Although those skilled in the art have been conducting intensive research in this area, a truly effective base isolation system that is economical, easy to install, long-lived and able to absorb potentially damaging seismic forces has not yet been found. At the same time prevent the collapse of the supported structure.

The present invention overcomes the above-mentioned problems and provides a novel rigidity isolation device which improves the anti-seismic protection of buildings and bridges. The isolation device of the present invention is used to isolate lateral stiffness from the load-bearing strength of the column system supporting the structure, thereby reducing the transmission rate of ground accelerations to the isolated structure.

In a preferred form, the invention contemplates the use of several long, relatively flexible, hollow pipes, with the upper ends partially secured to the structure to be protected and the other ends directed downward toward the foundation (or feet) extend. At least a portion (preferably all) of the pipe is filled with a material that dampens or damps induced movement of the pipe, preferably concrete. In addition, the entire isolation device includes means for connecting at least a portion of the pipes to the foundation, this connection being used to prevent the structure from tipping over. It is advantageous to connect the pipes to the foundation, but allow limited upward movement of the pipes against an increased biasing force.

The main carrier also forms part of the overall isolator. They are arranged at intervals relative to several pipe pieces. Typically for this purpose a hollow, integral concrete reinforcement column of square or circular cross-section is used, through which pipes extend downwardly. The supporting part is supported on the foundation and extends upward toward the structure to form an upper end. Bearings are interposed between the carrier and the structure so that they engage with each other and allow relative lateral movement therebetween.

In practice, a given building structure will be provided with such isolators, provided at all conventional load-bearing column locations, but provided with the support structures and internal pipework previously described.

Figure 1 is a partial view of a structural frame of a multi-storey building, with some parts broken for clarity, with an isolating device of the present invention mounted between the structural frame base and an underlying foot,

Fig. 2 is a partial view, in which some parts are broken, and some parts are partially cut away, showing the important parts of the isolating device,

Figure 3a is a sectional view along the line 3a-3a in Figure 2, with some components removed, showing the structure of an isolator, which uses a hollow square cross-section reinforced concrete column, and the corners of the column are respectively equipped with low-friction resistance stand,

Fig. 3b is a view similar to Fig. 3a, but wherein the isolation device adopts a hollow circular cross-section column and alternately arranged low-friction bearings,

Figure 4 is an exploded view of the components of a preferred support used in the present invention,

Figure 5 is an enlarged vertical sectional view of a preferred spring biased connector for securing the lowermost end of the pipe to the underlying building footing,

Figure 6 is a view similar to Figure 5 but for another type of spring-biased tubing connector,

Fig. 7 is a sectional view showing the components of an isolating device according to the present invention, which adopts several tube bundles and installs them in a hollow column,

Fig. 8 is an enlarged partial view showing the arrangement and orientation of pipe fittings in the embodiment shown in Fig. 7,

Figure 9 is a fragmentary view showing the fixing of one of the secondary reinforcing cables to the base of the building frame,

Fig. 10 is a cross-sectional view along line 10-10 in Fig. 5 . Further demonstrate the situation of pipe connection arrangement.

Referring now to the drawings, and in particular to Figure 1, there is shown a frame 20 of a multi-storey building with rigidity isolation means 22 between a base 24 of the frame 20 and an underlying concrete reinforced footing 26 , generally speaking, each spacer 22 comprises some long relatively flexible hollow pipes 28, a hollow, integral, upright bearing column 30 and the bearing column 30 surrounds the pipes 28, some of which are generally labeled with Supports indicated at 32 are placed between the lower end face of the frame 20 and the upper ends of the columns 30 .

In more detail, the frame 20 is a completely conventional piece comprising, in addition to the base 24, the usual uprights 34 and the various floor plates 36,38. Typically, frame 20 may be constructed of any desired construction material, such as reinforced concrete, providing conventional bearing surfaces 40 at strategic locations, which are part of base 24 . In the example shown, each support surface 40 is a pair of transverse horizontal beams 40a, 40b.

Likewise, the foundation 26 is also of conventional type (except for the changes associated here with the pipe 28 ), having footings 42 . The foundation 26 is also made of reinforced concrete.

Referring now to Figures 2 and 3a which show in detail one of the isolating means 22, it can be seen here that a plurality of tubes 28 are spaced apart from one another to form an array of peripheral tubes 28a and central tubes 28b. These fittings are conventional thin-walled metal structural tubing, typically in the diameter range of about 3/4 inch to 3 inches (inches). Each tube 28a, 28b is filled with a suitable damping material, here concrete 44 . The uppermost ends of the pipes 28 protrude into and are embedded in the reinforced concrete of the support surface 40 . As can be seen in FIG. 1 , the tubing extends upwardly through the base 24 into an associated post 34 . To enhance the rigid connection of the tube 28 to the frame 20, transversely extending flanges or snap rings may be used on the tube. More broadly, tubes 28 may be secured to a structural object such as frame 20 by any convenient and suitable means so long as a rigid and secure connection is formed between the structural object and the respective tubes. In the illustrated embodiment, the pipes 28 project into and are embedded in footings 42 of the underlying foundation 26 . Here too, suitable means can be used to connect the pipe fitting 28 and the foundation 26 in a manner that satisfies the operational requirements. Two preferred methods are described in detail below.

Each assembly 22 further includes an upright hollow integral main load bearing column 46 . In the embodiment shown in Figures 1-3a, the columns 46 are of square cross-section with vertical stiffeners 48 under each support. As shown in FIG. 2 , a metal reinforcement 50 passes through each spar 48 into the underlying foundation 26 for increasing the rigidity and lateral stability of the column 46 . In this regard it can be seen that posts 46 are supported on the top ends of feet 42 and extend upwardly towards frame 20 , with a standoff at the upper end of each post 46 .

The overall stand assembly 32 is made up of a number of comparable stand assemblies 54, each of which fits beneath a respective beam 40a, 40b. Each assembly 54 includes a base 56 of truncated triangular configuration that supports an upstanding support pad 58 made of a material with a relatively low coefficient of friction such as a bearing alloy composed of bronze, steel lead, or powdered sintered metal. , with or without lubrication). Near each corner of the base 56 is provided a hole 60 (see FIG. 4 ) for connecting the support plate 52 of the base 56 . In addition, stacked below each corner of the base 56 are a pair of opposite tapered mating wedge washers 62 , 64 with slotted holes aligned with the holes 60 . Three approximately J-shaped threaded connectors 66 are embedded in the posts 46 for each standoff assembly 54 and extend upwardly through the spacer slots and holes 60 . Secure the standoff assembly to the post with nuts 68. When the pads 62 and 64 of paired assembly are arranged, the height and position of each support assembly 54 should be adjustable, so as to avoid uneven load on the support, and the required position should be established on the support. Expected normal load.

Each stand-off pad 58 is engageable with the lower end surface of support surface 40 and is movable laterally relative to load column 46 and frame 20 . In order to facilitate this action, a metal slide 70 is secured to the lower end of each bearing surface 40 where the spacer 58 comes into contact with the bearing surface 40 . Each slide 70 is held in place by a number of bolts 72 embedded in the concrete, which may also be attached to a support surface constructed of conventional building materials.

Figure 36 shows a similar spacer 22 in which a hollow cylinder 72 is used. Column 72 is also provided with vertical stiffeners 74, spaced 90° from each other, as in the case of square column 46, in which interconnected stiffeners 50 are embedded. The isolator 22 of this embodiment also includes concrete filled pipes 28 and four standoff assemblies 54 above the stiffeners 74 . Four individual slides 78 are fastened to the lower end face of the respective bearing surface 40 to cooperate with the respective bearing pad 58 of each bearing assembly 54 .

In the preferred embodiment of the present invention, at least the peripheral tubes 28a of each tube arrangement in each column 46 or 72 are connected to ground or 20 such that the peripheral tubes are able to move upward relative to an increased biasing force. Make limited movement. Referring initially to Figures 5 and 10, one such connection arrangement is shown. Specifically, a pipe connection device 80 is provided, which includes a base fixed to the foot 42 for mounting pipes, has a lowermost support plate 82 and retaining rings 84 spaced apart from each other above the support plate 82 . In this embodiment, the support plate 82 and ring 84 are embedded in the concrete of the footing 42 . In addition, the retaining ring 84 is further secured against extraction by a nut and bolt assembly 86 also embedded in the foot 42 . The lowermost end of the tube 28a mounted in the device 80 is provided with a support plate 88 which is secured by welding or other suitable means. The support plate 88 is shaped and arranged to effectively retain the lowermost end of the tube 28a between the support plate 82 and the retaining ring 84 . A coil spring 90 is located between the support plate 88 and the ring 84 , disposed above the lowermost end portion of the tube 28 a installed in the device 80 . It can be understood from the figure. Tube 28a is movable upwardly against the bias of coil spring 90.

Fig. 6 shows another similar pipe connection device 92, this device 92 comprises a base 94 secured on the foot 42, it has an upwardly extending pin 96, and this pin 96 has a support plate 98 fixed on the upper end . Base 98 is fixed with embedded stud nut assembly 100 to prevent pulling out.

In this embodiment, the lowermost end of the tube 28a is hollow, and a mounting plate 102 and a retaining ring 104 are provided. As can be seen in Figure 6, the plate 102 is spaced upwardly from the lowermost end of the tube 28a but is located within the tube. On the other hand, retaining ring 104 is located below plate 102 but also within tube 28a. Ring 104 is circular and is slidably mounted on pin 96 . In this orientation, the support plate 98 and the ring 104 and the ring 104 cooperate to retain the upper end of the pin 96 between the mounting plate 102 and the ring 104 . Coil spring 106 is located between retaining ring 104 and mounting plate 102 , disposed above the upper end of pin 96 . It can also be seen here that the tube 28 can be moved upwards against the force of the spring 106 .

In the embodiment shown in Figures 1-3a and 36 the tubes 28 are spaced apart from each other, but the invention is not limited to this arrangement. For example, several tubes 108 (each filled with concrete) may be arranged in contact with each other to form a tube bundle arrangement. These pipes are also mainly filled with concrete 110 or similar damping material. The specific type of arrangement of the tubes is not critical, it is important that the tubes be positioned with sufficient spacing from the surrounding walls of the surrounding columns or other support members to prevent significant contact between the tubes and the support members in the event of an earthquake . Finally, integral hollow support columns are used in the preferred embodiment, but in practice the invention may also be used with spaced upstanding plates or the like, which are arranged above an array of tubes.

In order to provide the most effective protection against earthquakes, the isolation device of the present invention may be used with other devices for increasing the seismic resistance of a given structure (building). For example, referring to FIG. 1 , it can be seen that transverse flex cables 112 , 114 extend between base 24 and foundation 26 of frame 20 and are embedded therein. When installed, these cables are relatively loose. It is held in a suspended state (eg over a doorway 116 ) by retaining springs 118 . Those skilled in the art will appreciate that the cables 112, 114 may be used to prevent excessive lateral movement of the frame 20 relative to the foundation 16 under additional severe seismic conditions. The cables 112 , 114 may be connected by any suitable means, such as a cross pin 120 embedded in the base 24 , the ends of the cables being looped around the cross pin and secured by connectors 122 .

as an auxiliary measure. A concrete reinforced load bearing wall 24 is preferably provided between the foundation 26 and the base 24 . In particular, the upper bearing surface of the wall 124 is arranged slightly lower than the joint surface between the stand device 32 and the base 24 . This way in the event of total failure the building structure can rest on the load-bearing walls preventing total collapse of the entire structure.

During normal use of the isolator 22 , the primary structural loads are generated by the upstanding columns 46 or 72 through the intermediary of the respective stand assembly 54 . Pipes filled with concrete are only subjected to minimal pressure loads. As depicted, the main column 46 or 72 has no shear or moment connections to the supported structural item.

During earthquakes, the concrete-filled pipes and associated support columns are used to greatly reduce the transmission of ground accelerations to the isolated structure (building) and consequently reduce slippage (detachment) between floors . The concrete filled in each tube acts as a local stiffener and a shock absorber or attenuator during movement. In particular, the concrete filling helps to break down and dampen the movement in the direction of the shock absorber. The pipe also acts as a tension rod to prevent the protected structure from falling apart and tipping over in the event of an earthquake. In this regard, the use of a spring-biased pipe connection of the type described in Figures 5 and 6 is particularly advantageous as tipping moments increase. The pull to prevent tipping is also increased. Finally, the concrete-filled pipes control the natural cycles (phases) of the protected structure and provide restoring forces to return the earthquake-affected structure to its neutral position.

The bearing assemblies support the structure and transfer eccentric loads to the support columns to keep the structure in balance while maintaining its stability during forced vibratory motion. Thus, the bearing functions much like a roller bearing with little resistance to relative lateral movement between the structure and the support column.

The cross cables 112, 114 act as non-linear springs. Prevent excessive lateral movement, ie increase the lateral resistance of the structure when required. As long as the deformation is not large, the load-bearing wall 124 remains separated from the structure to be protected. When the magnitude of the earthquake is too great, that is, when the vertical displacement caused by the lateral deformation of the structure is large enough to bring the protected structure into contact with the load-bearing walls, these walls come into play, and they are deformed structures. Provides additional support strength and provides friction to absorb kinetic energy and reduce vibration amplitude.

The present invention thus provides several advantages not found in the prior art. For example, the isolators of the present invention are passive devices that absorb compressive and tensile loads. These devices have a long lifespan with little loss of strength and function over long periods of time. This is in contrast to the damaging aging process that occurs in the elastic rubber bearing pads used in the prior art. But more importantly, the isolation device of the present invention remains stable even under excessive lateral displacement caused by earthquakes, thereby keeping the protected structure in equilibrium during and between severe earthquakes. At the same time the isolation also provides high tensile strength to withstand tipping moments.

Although the application of the invention has been described primarily in the area of seismic resistance, the invention can be used in other areas as well. Examples can describe the present invention in this way. That is, isolating the lateral stiffness from the support strength of the columns can reduce temperature variations due to stresses in long span rigid frame bridges.

Claims (20)

1. A rigid isolation device usable between a building structure and an underlying foundation, said device being characterized in that it comprises a number of long, relatively flexible hollow tubes (28), the upper ends of which are connected to the structure Things (20) are connected. Extending downwards towards the foundation (26), at least some of the pipes are filled with material for damping the movement of the pipes, at least some of the pipes are connected to the foundation to prevent the structure from tipping over, and one is connected to the pipes (28) The supporting parts (46) arranged alternately are supported on the foundation (26) and extend upwards towards the structure. The seat device (32) is used for connecting the upper end and the structure, and can relatively move laterally therebetween. 2. Device according to claim 1, characterized in that the pipe elements (28) are arranged alternately. 3. 2. The device according to claim 1, characterized in that the tube elements (28) are arranged in a tube bundle in contact with one another. 4. 2. Device according to claim 1, characterized in that the pipe elements (28) are arranged in a pipe array. The tube array is made up of perimeter tubes (28a) and at least one inner tube (28b), said connection means securing the perimeter tubes to the foundation (26). 5. 2. The device of claim 1, wherein the damping material comprises concrete. 6. Device according to claim 1. It is characterized in that all pipes (28) are substantially filled with said damping material. 7. Device according to claim 1, characterized in that the main carrier (46) comprises an integral hollow column in which said tubular element (28) is housed. 8. 7. Device according to claim 7, characterized in that the cross-section of the column (46) is substantially square. 9. 7. Device according to claim 7, characterized in that the column (46) is substantially circular in cross-section. 10. According to the device of claim 1, it is characterized in that the support device comprises a base (56), which is fixedly connected with the upper end of the carrier (46), a support pad ( 58), the pad is made of a material with a relatively low coefficient of friction. 11. Apparatus according to claim 10, characterized in that the seat pad is made of a material selected from the group consisting of bearing alloys consisting of bronze, steel, lead, or powdered sintered metal with or Consists of no lubricants, etc. materials. 12. 2. Device according to claim 1, characterized in that the base (56) comprises adjustable spacer structures (62, 64) for the effective height of the stand device. 13. 10. Arrangement according to claim 1, characterized in that the structure (20) is at least partially made of concrete, and said pipes (28) are buried in concrete. 14. According to the device of claim 1, it is characterized in that several spaced support devices are respectively installed between the upper end of the carrier (46) and the structure (20), and jointly support the structure. 15. Device according to claim 1, characterized in that the load-bearing wall (70) is arranged slightly below the junction between the support device (32) and the structure (20). 16. According to the device of claim 1, it is characterized in that the connecting part comprises a base for installing the pipe, which is fixed on the foundation and has a lowermost support plate (82) and a circular retaining ring (84), the ring (84) Located above the support plate (82), it can be slidably installed on the lowermost end of the pipe fitting (28), a support plate (88) fixed on the lowermost end of the slidable installation pipe fitting, the shape of the plate (88) and The arrangement can effectively keep the lowermost end of the pipe between the support plate and the retaining ring, and a coil spring (90) is located between the support plate (88) and the retaining ring (84), and is arranged at a part of the lowermost end of the pipe (28) above. 17. Apparatus according to claim 1, characterized in that the connecting part comprises a base, which is fastened to the foundation, has an upwardly extending pin (96) and a support plate (104), which is connected to the pin ( 96), an assembly plate (98) and a retaining ring (104) connected to the lowermost end of the pipe fittings (28) to be connected, the assembly plate (98) is intersected with the lowermost end of the pipe fittings in the upward direction and is located in the pipe, The retaining ring (104) intersects the mounting plate in a downward direction, the retaining ring is circular and accommodates the pin (96), the mounting plate and retaining ring cooperate to retain the upper end of the pin between the mounting plate and retaining ring, a helical A spring (106) is positioned between the retaining ring (104) and the mounting plate (98) and is positioned over a portion of the pin (96) mounted within the tube. 18. According to the device of claim 1, it is characterized in that, cable member (112,114) extends between structure and foundation, and is fixed on structure and foundation, is used to prevent excessive relative movement between structure and foundation . 19. 2. Arrangement according to claim 1, characterized in that the structure (20) comprises a multi-storey building. 20. 10. Apparatus according to claim 1, wherein the connecting member includes a structural portion which permits limited movement of at least part of the tubular member in an upward direction against the increased biasing force.

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