JP2004270168A - Earthquake-proof reinforcement structure and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To heighten the yield strength of a foundation structure without the re-construction of an underground beam. <P>SOLUTION: In a lower structure 11 of an elevated bridge as this earthquake-proof reinforcement structure, a rigid frame 3 of reinforced concrete formed of columns 1, 1 and a beam 2 stretched between column capitals thereof is supported by piles 12, 12, and the columns 1, 1 are erected on footings 13, 13 installed on pile heads of existing piles. In the lower structure 11 of the elevated bridge, a new pile is provided as a pile 14 for reinforcing in a position separate from the existing piles 12, 12, and a footing 15 provided on the pile head of the pile for reinforcing and vicinities of both ends of the beam 2 are connected to each other through braces 16, 16. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a seismic reinforcement structure and a method mainly used in the field of civil engineering.
[0002]
[Prior art]
As bridges on which transportation vehicles such as railroads and automobiles travel, there are so-called viaducts that are continuously constructed in urban areas, in addition to narrow bridges that cross rivers and straits. From the viewpoint of efficient land use, such viaducts are constructed continuously on the road, on the railroad or in the space on the river. It also contributes to eliminating traffic jams.
[0003]
By the way, such a substructure of the viaduct is usually often constructed as a reinforced concrete rigid frame, but when designing and constructing it, the seismic resistance of the viaduct during an earthquake must be sufficiently studied.
[0004]
[Patent Document 1]
JP-A-2001-020228 [0005]
[Problems to be solved by the invention]
Under such circumstances, as shown in FIG. 6, the present applicant has constructed a lower part of a viaduct in which a damper 4 and a damper brace 6 composed of braces 5 and 5 are arranged in a reinforced concrete frame frame 3 composed of columns 1, 1 and beams 2. The structure 7 is proposed, and according to such a configuration, it is possible to greatly improve the earthquake resistance.
[0006]
However, when the above-described viaduct lower structure 7 is applied to an already constructed viaduct lower structure to perform seismic reinforcement, the following problems occur.
[0007]
That is, by arranging the damper brace 6 including the damper 4 and the braces 5 and 5 in the ramen frame 3, the strength of the ramen frame is certainly improved. Unless it is made larger, it does not mean that the lower structure 7 of the viaduct has been seismically reinforced as a whole.
[0008]
Therefore, in the case of a new construction, the strength of the foundation structure can be improved from the beginning by increasing the diameter of the pile, etc., but in the case of the existing construction, a new pile is provided and the pile is increased. The additional piles must be integrated with the existing piles by taking measures such as rebuilding the center beam.
[0009]
However, rebuilding of underground beams requires a lot of cost and time, and there is room for improvement from the viewpoint of economy.
[0010]
The present invention has been made in consideration of the above-described circumstances, and has as its object to provide an earthquake-resistant reinforcement structure and a method capable of increasing the strength of a foundation structure without reconstructing an underground beam or the like. I do.
[0011]
[Means for Solving the Problems]
In order to achieve the above object, the seismic retrofit structure according to the present invention, as described in claim 1, provides a new pile as an additional pile at a position separated from an existing pile supporting the rigid frame, and And the vicinity of both ends of the beam or the vicinity of the head of the column constituting the ramen frame are interconnected via a brace.
[0012]
Further, the seismic retrofit structure according to the present invention is characterized in that the ramen frame is composed of four pillars erected at the corners of the rectangular ground area and four beams connecting the heads of the pillars in a Lonno shape. And the additional pile is provided in the rectangular ground area.
[0013]
Further, in the seismic retrofit structure according to the present invention, the brace is connected to the vicinity of both ends of the beam via a mounting steel material fixed along the lower surface of the beam.
[0014]
Further, in the earthquake-resistant reinforcement structure according to the present invention, a damper is interposed between the pile head of the additional pile and the brace.
[0015]
Further, according to the seismic retrofitting method according to the present invention, a new pile is provided as an additional pile at a position separated from the existing pile supporting the frame, and a pile head of the additional pile and the ramen are provided. The vicinity of both ends of the beam constituting the frame or the vicinity of the head of the column is interconnected via a brace.
[0016]
In the seismic retrofit structure and method according to the present invention, a new pile is provided as an additional pile at a position separated from the existing pile supporting the rigid frame, and a pile head of the extra pile and a beam forming the rigid frame are provided. The vicinity of both ends or the vicinity of the head of the column are interconnected via a brace.
[0017]
In this case, in normal times when only a vertical load acts, the own weight of the ramen frame and the load on the ramen frame are mainly supported by the existing piles, and the flow of force is almost the same as before the seismic reinforcement. .
[0018]
On the other hand, when the horizontal force at the time of the earthquake acts on the frame, the horizontal force at the time of the earthquake does not flow to the existing piles as in the conventional case, but is partially transmitted to the piles via the braces.
[0019]
In other words, by installing braces, the horizontal strength of the ramen frame increases, but the horizontal strength of the pile, which is the foundation structure, also increases in the form of an increase in the horizontal resistance due to the additional piles, thus meeting the increase in the strength of the ramen frame. The proof stress of the foundation structure can be increased accordingly.
[0020]
The rate at which the horizontal force during an earthquake is transmitted to the existing pile and the additional pile is determined by the horizontal rigidity of the rigid frame and the rigidity of the existing pile and the horizontal rigidity of the brace and the additional pile. If the horizontal rigidity of the brace and the additional pile is increased depending on the ratio, it is possible to increase most of the horizontal force during the earthquake and transmit it to the pile.
[0021]
The additional pile does not necessarily have to be a vertical pile, but may be an inclined pile.
[0022]
The ramen frame is mainly intended for the ramen frame that constitutes the lower structure of the viaduct, but the present invention can be applied to structures for any use if seismic reinforcement is necessary. It does not matter whether it is in the civil engineering field.
[0023]
In addition, the ramen frame may be, for example, a structure whose cross-section is orthogonal to the bridge axis direction or parallel to the bridge axis direction, if a viaduct lower structure is described as an example. Furthermore, the ramen frame is not limited to a pair of pillars and a beam connecting the heads of the pillars, but may be applied to a three-dimensional frame frame.
[0024]
That is, the ramen frame is composed of four pillars erected at the corners of the rectangular ground region and four beams connecting the heads of the pillars in a rono shape, and the additional pile is A configuration provided in a rectangular ground area is conceivable.
[0025]
In such a three-dimensional frame structure, even if the horizontal force at the time of the earthquake acts from any of the X and Y directions, the additional force is reliably transmitted to the pile, so that an extremely stable earthquake-resistant reinforcing structure can be realized.
[0026]
When the pile head of the additional pile and the vicinity of both ends of the beam constituting the ramen frame are connected to each other via braces, the tip of the brace may be directly connected to the vicinity of both ends of the beam. Alternatively, it may be connected to the vicinity of both ends of the beam via a mounting steel material fixed along the lower surface of the beam.
[0027]
In such an indirect connection, the tensile force acting on the brace is distributed to the mounting steel and transmitted to the entire lower surface of the beam. In other words, the direct connection results in a concentrated tensile force, so a fixing structure that can withstand a large tensile force is required on the side of the rigid frame, whereas the indirect connection results in a dispersive tensile force. Then, a simple fixing structure is sufficient.
[0028]
The connection between the brace and the pile head of the additional pile may be made directly, or may be made indirectly via footing.
[0029]
Further, a damper may be interposed between the brace and the pile head of the additional pile.
[0030]
According to such a configuration, the vibration energy of the rigid frame is absorbed by the damping action of the damper, and the vibration of the rigid frame can be quickly converged.
[0031]
The damper may be of any type as long as it can absorb the energy of the relative horizontal vibration generated between the pile head of the extra pile and the brace. For example, an elastic-plastic damper such as a shear history type damper may be used. , Viscous material dampers, oil dampers, friction dampers and the like can be employed.
[0032]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of a seismic retrofit structure and method according to the present invention will be described with reference to the accompanying drawings. In addition, the same reference numerals are given to components and the like that are substantially the same as those in the related art, and description thereof is omitted.
[0033]
FIG. 1 shows a lower structure of a viaduct as an earthquake-resistant reinforcement structure according to the present embodiment. As shown in the figure, the viaduct lower structure 11 according to the present embodiment supports the reinforced concrete frame structure 3 composed of the columns 1 and 1 and the beams 2 bridged over the column capitals by the existing piles 12 and 12. The pillars 1, 1 are erected on footings 13, 13 installed on the pile head of the existing pile.
[0034]
Here, the lower structure 11 of the viaduct is provided with a new pile as a pile 14 at a position separated from the existing piles 12, 12, and near both ends of the footing 15 and the beam 2 provided at the pile head of the pile. Are interconnected via braces 16, 16. Note that the beam 2 referred to here means only the beam 2 constituting the ramen frame 3, and the projecting portions 17, 17 extending horizontally from the beam 2 to the sides of the columns 1, 1. Is not included in the beam 2.
[0035]
It is desirable that the additional pile 14 be disposed at an intermediate point between the existing piles 12, 12, and the braces 16, 16 be disposed within the plane of the ramen frame 3.
[0036]
The brace 16 can be made of, for example, H steel.
[0037]
In order to construct the earthquake-resistant reinforcement structure according to the present embodiment, first, an additional pile 14 is provided at an intermediate point between the existing piles 12, 12. The additional pile 14 may be a driven pile such as a steel pipe pile or a concrete pile, or may be a cast-in-place concrete pile.
[0038]
Next, a footing 15 is provided on the pile head of the additional pile 14, and then the lower ends of the braces 16, 16 are connected to the footing 15, and the upper ends thereof are connected to the lower surfaces near both ends of the beam 2, respectively.
[0039]
When connecting the braces 16, 16, the anchor bolts or concrete anchors buried in advance are used so that sufficient tensile strength against the assumed earthquake motion is secured on the bottom surfaces of both ends of the footing 15 and the beam 2. connect.
[0040]
In this way, in the normal state where only the vertical load P acts, as shown in FIG. 2A, the weight of the rigid frame 3 and the load on the rigid frame mainly depend on the existing piles 12,12. / 2 each, and the flow of force is almost the same as before seismic reinforcement.
[0041]
On the other hand, when the horizontal force H at the time of the earthquake acts on the frame 3, the horizontal force at the time of the earthquake is increased through the braces 16 and 16 and transmitted to the pile 14 as shown in FIG. with _b increases occur pile head pile 14, the remainder of the horizontal force is transmitted to the existing pile 12, 12 through the posts 1,1, respectively generating a horizontal reaction force H _f to the existing pile 12 and 12 I do.
[0042]
The ratio at which the horizontal force at the time of the earthquake is transmitted to the existing piles 12, 12 and the additional piles 14, respectively, is the horizontal rigidity of the ramen frame 3 and the rigidity of the existing piles 12, 12, the braces 16, 16 and the additional. If the brace section and the pile diameter of the additional pile 14 are set so that the brace horizontal rigidity is sufficiently larger than the rigid frame frame horizontal rigidity depending on the ratio of the brace horizontal rigidity to the combined rigidity of the pile 14, the horizontal force during an earthquake can be obtained. Most of the H can be transmitted to the pile 14.
[0043]
As described above, according to the seismic retrofit structure 11 and the method according to the present embodiment, by installing the braces 16, 16, the horizontal strength of the rigid frame 3 is increased, and the braces are newly provided. Since the horizontal strength of the entire pile, which is the basic structure, is increased by connecting to the additional pile 14, the underground beam is reconstructed or newly constructed as in the past, and the existing underground beam is connected through the underground beam. Even if the pile and the additional pile are not integrated, the strength of the foundation structure can be increased by the amount corresponding to the increase in the strength of the ramen frame 3.
[0044]
Therefore, it is possible to reinforce the ramen frame 3 in a shorter construction period than before, because there is no need to rebuild or newly construct the underground beam and integrate the piles via the underground beam.
[0045]
According to the seismic retrofit structure and method according to the present embodiment, by setting the cross-section of the braces 16 and the pile diameter of the additional pile 14 so that the horizontal rigidity of the brace is sufficiently larger than the horizontal rigidity of the rigid frame. Most of the horizontal force H during an earthquake can be increased and transmitted to the pile 14.
[0046]
Therefore, in addition to the above-described effects, the seismic strengthening of the columns 1 and 1 of the ramen frame 3 and the existing piles 12 and 12 is not required, and thus the construction period of the seismic strengthening work can be further shortened.
[0047]
In the present embodiment, the upper end of the brace is connected to the lower surface of both ends of the beam 2, but may be connected to the side surface of the column 1 instead of this.
[0048]
Further, in the present embodiment, the brace 16 is provided in the plane of the ramen frame 3. However, it is not always necessary to provide the brace 16 in the plane of the frame.
[0049]
As a specific configuration in this case, for example, a brace attachment member is fixed to the side surface near both ends of the beam 2, and is shifted from a virtual line connecting the existing piles 12, for example, by a column diameter in a direction orthogonal to the virtual line. In this case, the additional pile 14 may be provided at the position.
[0050]
Further, in this embodiment, the footing 15 is provided at the pile head of the additional pile 14 and the lower ends of the braces 16, 16 are connected to the footing. However, instead of this, the footing 15 is omitted and the brace is increased. It may be connected directly to the pile head of the pile 14.
[0051]
Further, in the present embodiment, the braces 16, 16 are directly connected to the footing 15 provided on the pile head of the additional pile 14, but instead, the braces 16, 16 and the footing 15 are provided between the braces 16, 16 and the footing 15. A shear history type damper as a damper may be interposed.
[0052]
FIG. 3 shows an earthquake-resistant reinforcing structure 31 showing such a modified example. In the earthquake-resistant reinforcing structure, the ramen frame 3 is supported by the existing piles 12, 12, similarly to the above-described embodiment. Is installed on the footings 13, 13 installed at the pile head of the existing pile, and a new pile is provided as an additional pile 14 at a position separated from the existing piles 12, 12. Although the footing 15 provided on the pile head of the pile and the vicinity of both ends of the beam 2 are interconnected via the braces 16, 16, in this modified example, the shearing is provided between the braces 16, 16 and the footing 15. The history type damper 32 is interposed.
[0053]
According to such a configuration, when the ramen frame 3 is horizontally vibrated by receiving a horizontal force during an earthquake, the horizontal vibration of the ramen frame 3 is repeatedly applied to the shear history type damper 32 through the braces 16 as forced deformation. The vibration energy of the rigid frame 3 is absorbed by the hysteresis damping of the shear history damper 32, and the horizontal vibration of the rigid frame rapidly converges. Of course, also in this case, the transmission of the horizontal force at the time of the earthquake to the existing piles 12, 12, and the additional pile 14 is as described in the above-described embodiment.
[0054]
Further, in the present embodiment, the ends of the braces 16, 16 are directly connected to the vicinity of both ends of the beam 2, but instead of this, the beam is attached via a mounting steel material fixed along the lower surface of the beam 2. 2 may be connected near both ends.
[0055]
FIG. 4 shows an earthquake-resistant reinforcing structure 41 showing such a modified example. In the earthquake-resistant reinforcing structure, the ramen frame 3 is supported by the existing piles 12, 12, similarly to the above-described embodiment. Is installed on the footings 13, 13 installed at the pile head of the existing pile, and a new pile is provided as an additional pile 14 at a position separated from the existing piles 12, 12. The footing 15 provided on the pile head of the pile and the vicinity of both ends of the beam 2 are connected to each other via braces 16, 16. In this modification, the footing 15 is attached between the braces 16, 16 and the beam 2. Steel material 42 is interposed.
[0056]
In such a configuration, a mounting steel material 42 having substantially the same length as the length of the beam 2 (the inner dimension between the columns 1 and 1) is fixed to the lower surface of the beam 2 using a concrete anchor or the like, and then the brace is used. The upper ends of 16 and 16 are joined to both ends of the mounting steel material 42 by bolts or welding, respectively.
[0057]
In such an indirect connection, the tensile force acting on the braces 16, 16 during an earthquake is distributed to the mounting steel 42 and transmitted to the entire lower surface of the beam 2. That is, since the direct connection results in a concentrated tensile force, a fixing structure that can withstand a large tensile force is required on the side of the rigid frame 3, whereas the indirect connection according to the present modification has a dispersive tensile force. Therefore, a simple fixing structure is sufficient on the ramen frame 3 side.
[0058]
In this modified example, it is of course possible to use the above-mentioned shear history type damper 32 together.
[0059]
Further, in the present embodiment, the ramen frame 3 is a flat ramen frame, but a three-dimensional ramen frame may be employed instead.
[0060]
FIG. 5 shows a viaduct lower structure 51 as an earthquake-resistant reinforcement structure showing such a modification. As can be seen from FIG. 5, the viaduct lower structure 51 is erected at a corner of a rectangular ground area 52. A ramen frame 55 composed of the four pillars 53 and four beams 54 whose heads are connected in a Lono-shape is supported by the four existing piles 12. Are erected on the footing 13 installed on the pile head of the existing pile.
[0061]
Here, the lower structure 51 of the viaduct is provided at the position apart from the existing piles 12 and 12 as a new pile in the rectangular ground area 52 as an additional pile 56, and is provided at the pile head of the additional pile. The footing 57 and the vicinity of both ends of the four beams 54 are interconnected via four braces 58.
[0062]
Here, with respect to the upper ends of the four braces 58, four brace mounting members 59 are respectively fixed to the inner side surfaces of the ends of the beams 54, 54 joined to the capitals of the four columns 53, respectively. The two brace mounting members 59 are connected to each other.
[0063]
According to such a three-dimensional frame structure, even if a horizontal force during an earthquake acts in any of the X and Y directions, the seismic force is reliably transmitted to the additional pile 56, thereby realizing an extremely stable seismic reinforcement structure. It becomes possible.
[0064]
In this modified example, the brace attachment member 59 may be omitted, and instead, the four braces 58 may be directly connected to the vicinity of both ends of the beam 54 or the vicinity of the capital of the column 53. Also in such a modified example, it is of course possible to use the above-mentioned shear history type damper 32 together.
[0065]
【The invention's effect】
As described above, according to the seismic retrofit structure and method according to the present invention, the underground beam is reconstructed or newly constructed as in the related art, and the existing pile and the additional pile are connected via the underground beam. Without the integration of the above, it is possible to increase the strength of the foundation structure by an amount corresponding to the increase in the strength of the rigid frame.
[0066]
Therefore, since it is not necessary to reconstruct or newly construct the underground beam and integrate the piles via the underground beam, it becomes possible to reinforce the ramen frame in a shorter construction period than before.
[0067]
[Brief description of the drawings]
FIG. 1 is a front view of an earthquake-resistant reinforcement structure according to an embodiment.
FIG. 2 is a view showing the operation of the earthquake-resistant reinforcement structure and the method according to the embodiment.
FIG. 3 is a front view of a seismic retrofit structure according to a modification.
FIG. 4 is a front view of an earthquake-resistant reinforcement structure according to a modification.
5 (a) is a perspective view and FIG. 5 (b) is a horizontal sectional view of the seismic retrofit structure according to the modification.
FIG. 6 shows a viaduct undercarriage according to the prior art.
[Explanation of symbols]
1,53 pillar 2,54 beam 3,55 ramen frame 11,31,41,51 Underpass structure (seismic reinforcement structure)
12 Existing piles 14,56 Additional piles 16,58 Brace 32 Shear history type damper (damper)
42 Steel for mounting

Claims (5)

A new pile is provided as an additional pile at a position separated from the existing pile supporting the ramen frame, and a brace is attached between the pile head of the extra pile and the vicinity of both ends of the beam or the column head near the ramen frame. A seismic retrofit structure characterized by being interconnected via The ramen frame is composed of four pillars erected at the corners of the rectangular ground area and four beams connecting the heads of the pillars in a rono shape, and the additional pile is formed in the rectangular shape. The seismic retrofit structure according to claim 1 provided in a ground area. The seismic retrofit structure according to claim 1 or 2, wherein the brace is connected to the vicinity of both ends of the beam via a mounting steel material fixed along a lower surface of the beam. The seismic reinforcement structure according to any one of claims 1 to 3, wherein a damper is interposed between the pile head of the additional pile and the brace. A new pile is provided as an additional pile at a position separated from the existing pile that supports the ramen frame, and the pile head of the extra pile and the vicinity of both ends of the beam constituting the ramen frame or the vicinity of the column head are interposed through braces. A seismic retrofitting method characterized in that they are connected to each other.

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