JP2007321354A - Reinforcing structure for square pier stud, reinforcing structure for base of the square pier stud, and method of constructing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To dispense with field welding of a square pier stud filled with concrete, and to improve the strength of the square pier stud without widening a width in a direction in which widening is constricted under conditions such as construction limitation etc. <P>SOLUTION: There is provided a reinforcing structure for an existing square pier stud having a square or rectangular cross section and obtained by filling concrete 12 in a steel shell pier stud. According to the reinforcing structure, a new square steel shell 30 is arranged so as to enclose the entire body of the existing square steel shell 10, and two surfaces of the new square steel shell 30 make intimate and rigid contact with two surface of the existing square steel shell 10 in the same direction. Further, concrete 40 is filled in expanded cross sectional space defined by the new square steel shell 30 and the existing square steel shell 10, as needed. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a reinforcing structure for a square pedestal, a reinforcing structure for the base of the rectangular pedestal, and a construction method thereof, and in particular, a steel shell suitable for use in a rectangular pedestal in an elevated part of an urban highway. The present invention relates to a reinforcing structure for an existing rectangular pedestal having a square or rectangular cross-section, in which the interior space of the pedestal is filled with concrete, a reinforcing structure for a rectangular pedestal base having the reinforcing structure, and a method for constructing them.

  It has been reported that many steel piers collapsed in the Great Hanshin Earthquake, and many of them were caused by buckling of the steel shell surface of the pier base in the out-of-plane direction.

  Therefore, as a measure for improving the proof stress of the existing steel pedestal, Patent Document 1 discloses, as shown in FIG. 1, filling the hollow interior of the square steel shell 10 constituting the steel pedestal 10 with concrete, As shown in FIG. 2, a steel inner cylinder 14 is erected in the hollow interior, and concrete space 12 is filled into the annular space between the inner cylinder 14 and the square steel shell 10 which is an existing pedestal. Are listed. In the figure, 16 is a cross beam portion, 22 is a footing, and 24 is a foundation.

  Here, the concrete 12 is filled into the rectangular steel shell 10 by preventing the buckling of the steel shell by filling the concrete into the steel shell, and the strength of the leg itself against the compressive force acting on the cross section of the steel shell. It is for improving.

Japanese Patent Laid-Open No. 8-326014 (FIGS. 1 and 7)

  However, rectangular steel piers that support elevated sections of urban expressways have been installed on existing piers due to increased dead loads due to widening of elevated roads, etc., or increased seismic loads and increased live loads due to revised design standards. The static proof stress of may be insufficient. Furthermore, the dynamic yield strength at the time of an earthquake becomes inadequate, and it becomes necessary to attach a reinforcing structure to compensate for these.

  For example, the specifications for road bridges have recently been changed to a system of live loads in line with the actual situation, and piers designed according to the old specifications may be insufficient in proof strength based on current standards. If you continue to use the current old piers, you may have to leave this state, but if the road on the road is widened or new members are added to reinforce, At the same time, the strength of the pier itself is required to be improved so as to conform to the latest specifications.

  However, when trying to cope with the normal reinforcement technique, the following problems occur.

  (1) When a reinforcing structure such as an additional steel shell is attached by on-site welding, the old steel legs are often of poor quality and cannot withstand welding due to fatigue damage or delamination. In addition, it is difficult to ensure the quality of welding because there is heavy traffic on the viaduct and vibrations.

  (2) When giving up welding and considering mounting with high strength bolts (HTB), if the concrete is already filled in the existing square steel shell by the strength improvement measures as described in Patent Document 1, The reinforcement structure cannot be attached with high strength bolts. A method of drilling holes from the outer shell into the filled concrete and attaching it with one-side bolts is also possible, but not only is there any doubt about the anti-corrosion and durability of the one-side bolts, but also after checking the looseness of the one-side bolts Maintenance needs to be continued forever.

  (3) Although stud bolts are planted on the outer shell and a reinforcing structure is attached, it is conceivable to constrain local buckling of the steel sheet with these methods, including attachment with the above-mentioned high-strength bolts or one-side bolts. Since the structure is only the vertical rib inside the existing leg, the stiffening rigidity is insufficient.

  (4) Existing square steel shells are usually formed into squares using square welding, but there are many cases where they are constructed according to the conventional practice. In addition, there is a shortage in the transmission of shear stress due to the design, and if there is no additional welding repair of this part, this part may have insufficient proof stress.

  (5) The viaduct with such pedestals is often a general road parallel to the elevated road, and due to the limitations of building limits, the pedestal is widened in a direction perpendicular to the direction of the road. Is often impossible.

  The present invention has been made to solve the above-mentioned conventional problems, and even a square pedestal already filled with concrete does not need to be welded on site, and widening is restricted by conditions such as building limits. It is an object to reinforce the pedestal without widening in the direction.

  The present invention is a reinforcing structure for an existing square pedestal with a square or rectangular cross section filled with concrete inside the steel shell pedestal so that the new square steel wrap encloses the entire existing square steel sphere. And the two steel shell surfaces of the new square steel shell are fixed in close contact with the two surfaces of the existing square steel shell in the same direction. Is a solution. Furthermore, if necessary, the expanded cross-sectional space formed between the new square steel shell and the existing square steel shell is filled with concrete and synthesized to enhance the effect of reinforcement and economy. Can do.

  Here, the reason why the new square steel shell is arranged so as to wrap the entire existing square steel shell is as follows. In other words, such reinforcement of the legs is generally in service, that is, it is necessary to be constructed without blocking the traffic on the road, and when temporarily building a temporary pier that replaces the existing legs Except for, there is no way to completely replace the new structure with the existing legs. On the other hand, it is often impossible to install an alternative temporary pier in an urban area with many restrictions. Therefore, the reinforcement is inevitably in a structure that surrounds the existing legs. By adopting such a structural form, it is possible to design based on a policy of adding and reinforcing a new structure while utilizing an existing steel shell.

  In addition, it is desirable that the new steel shell surface be square from the viewpoint of improving the performance of the uniform cross section, but in order to guarantee the strength against buckling of the steel shell, it is necessary to attach ribs that stiffen the steel shell. Become. For directions that are not subject to area restrictions such as building limits, the cross section can be enlarged, and ribs can be inserted into the enlarged parts, but the cross section cannot be enlarged in the directions subject to restrictions, and rib mounting is not possible. Is possible. In this direction, the new steel shell is brought into close contact with the existing steel shell, thereby minimizing expansion and preventing the buckling by fixing the new steel shell to the filled concrete in the existing steel shell.

  The base of steel piers is often filled with concrete for the purpose of improving earthquake resistance and preventing damage and collapse of piers caused by collisions with large vehicles. The same situation. In addition, if the concrete and steel shell to be filled are made into a composite structure, the structure of the reinforcing cross section can be made compact, and the anticorrosion work inside the steel shell becomes unnecessary, so that cost reduction during reinforcement and easy maintenance can be achieved. .

  The new square steel shell two shells and the existing square steel shell two surfaces are closely fixed by a post-installed anchor such as a chemical anchor or a hole-in anchor, and the ribs are omitted. Also, a structure capable of ensuring the strength against buckling can be obtained.

  In addition, on the inner surface on the enlarged cross section side of the new square steel shell and on the outer surface on the enlarged cross section side of the existing square steel shell, a stagger (synthetic mechanism) such as a stud diver or a perforated steel plate gibel (PBL) is provided. It can be arranged. Here, all members such as stud gibber and PBL are manufactured in advance in the factory, and can be easily attached at the site simply by drilling the existing steel shell and filled concrete in order to install the post-construction anchor.

  According to the present invention, a stopper is disposed at a portion below the ground surface of the square steel shell having the above-described reinforcing structure, and an anchor bar is installed and fixed after drilling in the footing, and the anchor bar and the stopper are sheared. It is connected by a reinforcing bar, and concrete is cast around a portion below the ground surface of the rectangular steel shell, a detent, an anchor bar and a shear bar, and these are made into an integral structure. A reinforcing structure for a rectangular pedestal base is provided.

  The present invention is also a method of constructing a reinforcing structure for an existing square pedestal having a square or rectangular cross section, in which concrete is filled in the steel shell pedestal, and the new square steel shell is replaced with the existing square steel. The reinforcing structure of the rectangular pedestal is characterized in that it is arranged so as to wrap the entire shell, and the two steel shells of the new square steel shell are fixed in close contact with the two sides of the existing square steel shell in the same direction. A construction method is provided. Furthermore, if necessary, a composite structure can be formed by filling concrete in an enlarged cross-sectional space formed between the new square steel shell and the existing square steel shell.

  In the present invention, a stopper is provided at a portion below the ground surface of the square steel shell having the above-described reinforcing structure, and after anchoring the anchor bar after drilling, the anchor bar and the stopper are sheared. A rectangular structure characterized by connecting concrete by reinforcing bars and placing concrete around a portion below the ground surface of the rectangular steel shell, a detent, an anchor bar and a shear reinforcing bar, thereby forming a unitary structure. The reinforcement structure of the pedestal base is provided.

  In the present invention, a new rectangular steel shell is disposed so as to cover the existing rectangular steel shell, so that it is a closed cross-sectional structure surrounding the existing leg, and the cross-sectional area and In addition to increasing the amount of cross-section such as the secondary rigidity of the cross-section, the problem can be avoided and the pier proof strength can be improved even when the welding amount of the existing steel shell is insufficient.

  In addition, since the two steel shells of the new square steel shell are tightly fixed to the two sides of the existing square steel shell in the same direction, the widening in the direction in which the widening is restricted by conditions such as the construction limit of the roadway is performed. There is no need.

  Usually, there are few place restrictions about a road axis direction, and a comparatively big reinforcement structure can be attached to this direction. However, in this case as well, on-site welding attachment and high-strength bolt attachment are often denied for the reasons described above. Therefore, in this direction, for example, studs such as studs are planted on the outer shells of the existing legs, studs such as studs and PBL are provided on the inner surface of the reinforcing structure, and the reinforcing structure is filled with concrete. Thus, it is possible to construct a synthetic cross section and reinforce it while utilizing the existing outer shell material.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  As shown in FIG. 3, the pedestal portion of the present embodiment is a reinforcing structure for an existing rectangular pedestal having a rectangular cross section in which the internal space of the existing steel shell pedestal is filled with concrete 12 as shown in FIG. 3. A new square steel shell 30 is arranged so as to wrap around the entire existing square steel shell 10, and two steel shell surfaces (left and right surfaces in the figure) of the new square steel shell 30 are the same as those of the existing square steel shell 10. Concrete space 40 is filled in an enlarged cross-sectional space formed between the new square steel shell 30 and the existing square steel shell 10, which are in close contact with two surfaces in the same direction.

  A stud 34 (synthetic mechanism) such as a stud 36 is provided on the outer surface of the existing square steel shell 10 on the enlarged sectional side (upper and lower sides in the figure), and an inner surface of the new rectangular steel shell 30 on the enlarged sectional side. Arranged.

  The steel shell 2 surface of the newly disposed square steel shell 30 and the steel shell 2 surface of the existing square steel shell 10 are closely fixed by a post-installed anchor 32 such as a chemical anchor or a hole-in anchor. .

  In addition, although the said reinforcement structure is about the structure above the ground, the structure which transmits the cross-sectional force which flowed to this part smoothly to foundation structures, such as an underground footing, is further required.

  FIG. 4 shows the vertical cross-sectional shape of the embodiment of the base having such a configuration, and FIG. 5 shows the horizontal cross-sectional shape. The anchor bolt 26 is embedded in the footing 22 as a structure that plays this role for the existing pier, but it is practically impossible to expand and reinforce the structure itself because the structure is embedded in the concrete. It is. Therefore, the reinforcement of the ground part is considered as a composite structure, and the anchor muscle 50 necessary for the base part is installed and fixed, and it is extended and fixed to the footing 22 so that the cross-sectional force flowing in the reinforcement structure can be reduced. Can be communicated to.

  Specifically, a slip stopper 52 is provided in a portion below the ground surface of the rectangular steel shell 30 having the reinforcing structure shown in FIG. 3, and anchor bars 50 are installed and fixed in the footing 22 after drilling. The bar 50 and the stopper 52 are connected by the shear reinforcing bar 54, and the concrete 60 is placed around the part below the ground surface of the rectangular steel shell 30, the stopper 52, the anchor bar 50, and the shear reinforcing bar 54. Thus, these are integrated.

  In this way, by performing the reinforcement within a range that does not appear on the ground surface, the reinforcement can be performed without violating the building limit, and the reinforcement can be performed in each of the column axis direction and the direction perpendicular to the column axis.

  In the above embodiment, the present invention is applied to a road viaduct, but the application target of the present invention is not limited to this.

Perspective view showing an example of a conventional steel pedestal, with a part cut away A perspective view showing another example, with a part cut away 4 is a horizontal sectional view taken along the line AA of FIG. 4 showing an embodiment of a reinforcing structure for a rectangular pedestal according to the present invention. FIG. 5 is a vertical sectional view taken along line DD of FIG. 5, showing an embodiment of a reinforcing structure of a rectangular pedestal base. FIG. 4 is a horizontal sectional view taken along the line BB in FIG. 4 showing an embodiment of the reinforcing structure of the rectangular pedestal base.

Explanation of symbols

10 ... Rectangular steel shell (existing)
12, 40, 60 ... Concrete 22 ... Footing 26 ... Anchor bolt 30 ... Square steel shell (new)
32 ... Post-installed anchors 34, 36 ... Stud
50 ... Anchor reinforcement 52 ... Non-slip 54 ... Shear reinforcement

Claims (6)

A reinforcing structure for an existing square pedestal with a square or rectangular cross section filled with concrete inside the steel shell pedestal,
A new square steel shell is placed to wrap the entire existing square steel shell,
A reinforcing structure for a rectangular pedestal, wherein two surfaces of the new square steel shell are fixed in close contact with two surfaces of the existing rectangular steel shell in the same direction.   2. The reinforcing structure for a square pedestal according to claim 1, wherein the two steel shells of the new square steel shell and the two steel shells of the existing square steel shell are firmly fixed by a post-installed anchor. .   The square pedestal according to claim 1 or 2, wherein a stopper is disposed on the inner surface of the new square steel shell on the enlarged cross section side and on the outer surface of the existing square steel shell on the enlarged cross section side. Reinforcement structure. A slip stopper is disposed in a portion below the ground surface of the square steel shell having the reinforcing structure according to claim 1,
Anchor holes are installed and fixed after drilling in the footing,
The anchor bar and the stopper are connected by a shear reinforcement bar,
Reinforcement of the base of the square pedestal characterized in that concrete is cast around the part below the ground surface of the square steel shell, the stopper, the anchor reinforcement and the shear reinforcement, and these are integrated. Construction. A method of constructing a reinforcing structure for an existing square pedestal with a square or rectangular cross section, in which concrete is filled in the steel shell pedestal,
Place a new square steel shell so that it encloses the entire existing square steel shell,
A method for constructing a reinforcing structure for a square pedestal, characterized in that the two steel shells of the new square steel shell are fixed in close contact with the two surfaces of the existing square steel shell in the same direction. A stopper is provided in a portion below the ground surface of the square steel shell having the reinforcing structure according to claim 1,
Anchor holes are installed and fixed after drilling in the footing,
The anchor bar and the stopper are connected by a shear reinforcement bar,
Reinforcing structure of a rectangular pedestal base, wherein concrete is cast around a portion below the ground surface of the rectangular steel shell, a stopper, an anchor bar, and a shear reinforcement bar, so that they are integrated. Construction method.

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