JP5512868B1 - PC girder bridge structure - Google Patents

Abstract

A PC girder bridge that prestresses concrete in a main girder by placing PC steel in a curved shape at the lower section of the central section of the span spanned from both sides and projecting in a cantilevered state, and fixing the tension. Provide structure.
SOLUTION: A bridge girder constructed by an overhanging concrete block made of cast-in-place concrete for each section by means of an overhanging construction method between bridge piers, and a main girder of a central section serving as a confinement section 10 between spans. Except for the main girder cross section, PC steel is continuously arranged, and at the lower section of the central section, through the section, at least one adjacent section, the upper surface side or the lower surface side of the extended bridge body block of the next section PC steel material 8 is arranged in a curved shape over the main body, and the PC steel material of the main girder cross section and the PC steel material 8 arranged at the lower part of the main girder cross section of the central section are tension-fixed, thereby prestressing the concrete of the main girder. By giving, the closing part 10 of a center division is integrally connected with an overhang bridge body block.
[Selection] Figure 1

Description

  The present invention relates to a PC girder bridge structure.

  When building bridges related to railways, roads, etc. on steep valleys, rivers, or oceans, if a support work cannot be performed due to the location under the bridge, one bridge girder cantilevered right and left from the pier. The so-called cantilever erection method, which is constructed sequentially, is adopted. In this method, a movable rail is temporarily fixed on an existing bridge block, and a mobile work vehicle (wagen) is installed on the rail so that it can move forward and backward. A formwork support member and scaffolding are extended and supported forward, and the formwork, rebar, PC steel, etc. are assembled on this support member, concrete is placed, and prestress is introduced into the block. It is well known to construct a girder bridge built on site.

  As a first prior art related to the public knowledge, in constructing an on-site stretched girder bridge using a corrugated steel sheet as a web, a corrugated steel sheet web having a length corresponding to a plurality of blocks of the bridge body is projected from the existing bridge body block. The new bridge body concrete is a construction method in which the corrugated steel sheet web is sequentially overhanged for each block (see Patent Document 1).

  According to this construction method, when a corrugated steel sheet is used to construct an on-site stretched girder bridge, the corrugated steel sheet web having a length corresponding to a plurality of blocks of the bridge body is connected to the existing bridge body block. By laying the upper and lower floor slab concrete in multiple times for each block length, constructing a new bridge block, and then repeating the process of connecting the corrugated steel web of the next multiple block length, The processing and connecting man-hours of the connecting portion of the steel plate web can be reduced, and the effect of contributing to the reduction of the overall cost is great.

  In addition, as a second related art which is publicly known, in the bridge erection method by the cantilever method in which one end is supported on the bridge support base, the cast-in-place concrete is placed for each section and is sequentially extended in the longitudinal direction, For each section, the steel frame is cantilevered in the longitudinal direction, PC steel is stretched along the steel frame, both ends are supported by the steel frame, and tension is applied to the steel frame, Bridge construction that casts in-situ concrete supported by the steel frame to form a single-section steel-concrete structure, and then applies prestress in the longitudinal direction continuously after the solidification of the concrete. It is a method (refer patent document 2).

  According to this cantilever construction method, the steel frame constituting the steel-concrete structure is first stretched, prestressed, and the formwork is supported. The load becomes large and the length of one section can be made larger than before, the work efficiency is improved, the work period is shortened, and prestress is applied to the steel frame itself, and the concrete In addition, because it is a steel-concrete structure with pre-stress applied, the strength of the steel frame can be used as a target for strength calculation such as load resistance, and it can be made a lightweight and long-span bridge. Is.

  Furthermore, although it is not a publicly known technology, a prior invention related to the same applicant as the present invention has been filed as Japanese Patent Application No. 2012-230592. This invention of the prior application is a bridge girder constructed with a stretched bridge body block, and a steel frame and concrete, which are arranged in addition to each section, are integrally formed and constructed continuously in the length direction. The PC steel material is continuously arranged at the upper part of the cross section of the main girder except for the main girder of the central section that becomes the closing portion between the sections, and the bridge bridge block of the adjacent section penetrates the section at the lower section of the central section. PC steel is arranged in a curved shape over the upper surface, and the PC steel at the upper part of the main girder cross section and the PC steel material arranged at the lower part of the main girder cross section of the central section are tensioned and fixed to the concrete of the main girder. This is an SPC girder bridge structure to which stress is applied (see Patent Document 3).

  According to the SPC girder bridge structure of the invention of the prior application, PC steel is continuously arranged on the steel frame and the upper part of the main girder cross section, which are continuously arranged for each section, and the tension is fixed. PC steel material is placed in a curved shape across the adjacent compartments through the compartments, and the tension is fixed, so that the closed part of the central compartment is rigidly connected to the overhanging bridge block and is integrally connected. The structural form of can be a rational structure, the girder height at the pier end can be greatly reduced, and the SPC girder bridge can be obtained that is excellent in strength and stability even if the span length is long. That's it.

JP 2001-200510 A Japanese Patent Laid-Open No. 02-243809 Japanese Patent Application No. 2012-230592

  In the first prior art, a corrugated steel sheet web having a length corresponding to a plurality of blocks of a bridge body is connected to an existing bridge body block, and upper and lower floor slab concrete is placed in a plurality of times for each block length. A bridge that is erected from both sides (left and right) by constructing a new bridge block, introducing prestress into the block, and then repeating the process of connecting corrugated steel webs of the length of the next multiple blocks It is said that a girder bridge will be constructed with a body block, but the bridge blocks that are erected from both sides must be joined together at the central part and connected at the closed part. There is no mention at all about the connection at the section, it is also unclear what the central section leading to the closure is, and it is closed by the bridge block that is erected from both sides substantially. There is a problem that can not be.

  Also, in the second prior art, a steel frame is added to each block and overhangs in a cantilever state, and a cast-in-place concrete is placed on the steel frame to support a formwork, and a section of the steel concrete structure is sequentially formed. It is a method to form a bridge by molding, but also in this method, a steel concrete structure is sequentially molded for each section from both sides, and the bridge is constructed, but it is connected at the closed part at the center Is not mentioned, and has the problem that the steel-concrete structure constructed sequentially from both sides cannot be closed in the central compartment.

  Therefore, in the prior art, since the central section (closed portion) between the spans that are overhanged and constructed in a cantilever state is in a hinge state and remains in the cantilever form, the span length is long. The center section of the span length is not applicable to the vehicle, and vibrations caused by vehicles and winds that are constantly received are not uniform left and right, so it is not only easily deformed and easily damaged, but also requires frequent maintenance and high running costs. Furthermore, after the completion of construction, the concrete is subject to drying shrinkage and clique deformation due to the prestressing force in the longitudinal direction of the bridge girder. Cause trouble. In any case, there is a problem to be solved in that the closed portion that is erected from both sides and butts at the central portion is made into a solid section.

  In the third technology of the prior invention, the problem of the prior art is solved by arranging a PC cable in the closing portion and rigidly coupling it. By the way, in the case of the invention of the prior application, since the steel frame is built in, it works effectively when the span is a long span, but it is not a general girder bridge with a long span or a main trunk road. When the load is relatively small as an ordinary road, the use of an expensive steel frame is unnecessary and the cost is high, and a normal PC girder bridge is sufficient. Moreover, since the built-in steel frame is to be connected for each section, the problem that it cannot be applied to the segment block method has not been solved.

  The present invention provides a bridge girder constructed as a concrete bridge or a block of an overhang bridge body made of cast-in-place concrete or a segment block by means of an overhanging construction method between bridge piers as a concrete means for solving the problems of the conventional example described above. In addition, concrete blocks formed by adding up each section are continuously constructed in the length direction, and PC steel is continuously arranged on the main girder cross section except for the main girder of the central section that becomes the closing part of the span. In addition, the PC steel material is arranged in a curved shape over the upper surface side or the lower surface side of the overhanging bridge block of the next section through the section and at least one adjacent section at the lower section of the central section, The PC girder is prestressed by tension fixing between the PC steel material of the main girder cross section and the PC steel material arranged at the lower part of the main girder cross section of the central section. It is intended to provide a structure.

  In this invention, the PC steel material continuously arranged in the main girder cross section excluding the main girder of the central section that becomes the closed portion between the diameters is arranged on the upper surface side or the upper surface side and the lower surface side of the main girder cross section. And the PC steel material is tension-fixed every predetermined section and prestress is introduced into the main girder; and adjacent sections passing through the section in the upper section of the main girder of the central section serving as the closing portion As an additional requirement, the PC steel material is disposed over the upper surface of the overhang bridge body block and is tension-fixed on the upper surface of the adjacent section.

According to the PC girder bridge structure according to the present invention, a concrete block formed by adding up each section is continuously constructed in the length direction, and the main girder is excluded except for the main section of the central section that becomes a closed portion between spans. PC steel is continuously arranged in the cross section, and at the bottom of the cross section of the central section, through the section and at least one adjacent section, over the upper surface side or the lower surface side of the overhang bridge body block of the next section PC steel is arranged in a curved shape, and pre-stress is applied to the concrete of the main girder by the tension fixing of the PC steel of the main girder cross section and the PC steel arranged at the lower part of the main girder cross section of the central section. As a result, the closed section of the central section is rigidly connected to the overhanging bridge block and is integrally connected, and the structural form of the completed system becomes a rational structure by tension fixation of the PC steel material without using steel frames, Significantly increased the girder height at the pier end It can be reduced, and the concrete drying shrinkage and creep deformation in the longitudinal direction of the bridge girder prevents cracks in the concrete in the closed part and the use trouble due to the opening of the mouth, and a strong and stable PC girder bridge can be obtained. At the same time, by eliminating the need for the built-in steel frame, the construction cost can be greatly reduced.
Furthermore, by placing PC steel on the upper and lower sides of the main girder cross section including the central closing part, prestress is applied to the entire cross section of the bridge including the central closing part. Even if tensile stress is generated at the upper and lower ends of the cross section due to vibration loads such as the above, they are canceled out and cracks are not generated in the closed portion, so that the safety and durability of the entire bridge can be ensured.

1 shows a PC girder bridge structure according to a first embodiment of the present invention, in which an overhanging bridge body block is sequentially constructed with cast-in-place concrete from a bridge support base that is built in advance in a region to be installed. It is explanatory drawing which showed the side surface schematically. In the PC girder bridge structure according to the embodiment, it is a side sectional view schematically showing a bridge support base. In the PC girder bridge structure according to the embodiment, it is a side cross-sectional view schematically showing a state in which a first-stage overhanging bridge block is constructed on a bridge support base serving as a reference. It is a schematic expanded sectional view which follows the II line | wire of FIG. In the PC girder bridge structure according to the embodiment, it is a side cross-sectional view schematically shown to explain the situation of sequentially constructing the second and subsequent overhanging bridge blocks based on the bridge support base. . It is a schematic expanded sectional view which follows the II-II line of FIG. FIG. 7 shows a PC girder bridge structure according to a second embodiment, in which a bridge side surface in which an overhanging bridge block is sequentially constructed by cast-in-place concrete from a bridge support base that is built in advance in an area to be installed is roughly shown. It is explanatory drawing shown illustratively. It is a schematic expanded sectional view which follows the III-III line of FIG. FIG. 9 shows a PC girder bridge structure according to a third embodiment, in which a side surface of a bridge body constructed of cast-in-place concrete blocks in order from a bridge support base constructed in advance in a region to be installed. It is explanatory drawing shown schematically. FIG. 10 is a schematic enlarged sectional view taken along line IV-IV in FIG. 9. FIG. 9 shows a PC girder bridge structure according to a fourth embodiment, in which a side surface of a bridge body constructed from cast bridge concrete blocks in order from a bridge support base constructed in advance in a region to be installed is cast in place. It is explanatory drawing shown schematically. FIG. 7 shows a PC girder bridge structure according to a fifth embodiment, wherein a bridge body side surface constructed by a cast-in-place concrete is sequentially constructed from a bridge support base constructed in advance in a region to be installed. It is explanatory drawing shown schematically. In the PC girder bridge structure according to the embodiment, it is a side sectional view schematically showing a bridge support base. In the PC girder bridge structure according to the embodiment, it is a side cross-sectional view schematically showing a state in which a first-stage overhanging bridge block is constructed on a bridge support base serving as a reference. It is a schematic expanded sectional view which follows the VV line of FIG. It is a schematic expanded sectional view which follows the VI-VI line of FIG. FIG. 10 shows a PC girder bridge structure according to a sixth embodiment, in which a bridge body side surface constructed by cast-in-place concrete is sequentially constructed from an overhanging bridge body block from a bridge support base constructed in advance in an area to be installed. It is explanatory drawing shown schematically. It is a schematic expanded sectional view which follows the VII-VII line of FIG. FIG. 9 shows a PC girder bridge structure according to a seventh embodiment, in which a bridge body side surface in which an overhanging bridge body block is sequentially constructed with cast-in-place concrete from a bridge support base that is constructed in advance in an area to be installed. It is explanatory drawing shown schematically. It is a schematic expanded sectional view which follows the VIII-VIII line of FIG. FIG. 9 shows a PC girder bridge structure according to an eighth embodiment, in which a bridge body side surface in which an overhanging bridge body block is sequentially constructed by cast-in-place concrete from a bridge support base that is constructed in advance in an area to be installed; It is explanatory drawing shown schematically.

  The present invention will be described in detail based on the illustrated embodiment. First, in the PC girder bridge according to the first embodiment shown in FIGS. 1 to 6, FIG. 1 schematically shows the structure of a PC girder bridge that is bridged in a region to be constructed such as a river or a harbor. It is explanatory drawing of the bridge body side shown schematically, Comprising: First, the bridge support base 1 is constructed | assembled with a required space | interval in the field. The bridge support base 1 includes a pier 2 and a head 3 integrally formed at a bridge level position designed on the upper portion of the pier 2.

  At both ends of the head 3 of the bridge support base 1, for example, although not shown, a plurality of overhanging bridge bodies serving as main girders are used using an appropriate mobile work vehicle (wagen) as in the conventional example. The blocks A1 to An are made of cast-in-place concrete, and the blocks are built in a cantilevered state by assembling the formwork one block at a time, and the bridge is constructed. The blocks defined between the piers are preferably odd in design. In addition, each overhang bridge body block that constitutes the main girder of the bridge is called a box girder, and it is natural that the reinforcing bars are arranged in an appropriate state, so The illustration and explanation are omitted.

  As shown in FIG. 2, a plurality of (for example, nine) sheaths 4 are preliminarily arranged near the upper portion of the head 3 of the bridge support base 1 at a predetermined interval in the width direction. The extended bridge body block A1 constructed on both sides is also arranged in the state where the same sheath 4 is continuously and communicated at the same level position, and is constructed with cast-in-place concrete.

  Then, as shown in FIG. 3, after the concrete of the overhang bridge block A1 constructed on both sides of the head 3 is hardened, the PC steel material 5 is inserted into the sheath 4, and both ends of the PC steel material 5 are The fixing member 6 that also serves as a connection fixes the tension at the end of the both-extending bridge body block A1, and applies prestress to the head 3 and the both-extending bridge body block A1 to integrate them. As shown in FIG. 4, the overhang bridge body block A <b> 1 constructed integrally by being connected in this way has a plurality of PC steel materials 5 on at least the upper surface side of the head 3 and the overhang bridge body block A <b> 1. Since the tension is fixed, bending as a bridge body is suppressed.

  Next, as shown in FIG. 5, an overhang bridge body block A2 is constructed for the overhang bridge body block A1, and in the construction of the overhang bridge body block A2, the same sheath as described above is used. The PC steel material 5a is disposed at the same level by being inserted into 4a, and the end portion of the PC steel material 5a is connected to the fixing member 6 to which the PC steel material 5 is tension-fixed via a connecting tool 7 such as a joint coupler. Connect and construct the overhang bridge block A2 with cast-in-place concrete. After the concrete of the overhanging bridge body block A2 is hardened, the end of the PC steel material 5a is tension-fixed by the fixing member 6a that also serves as a connection at the end of the overhanging bridge body block A2 in the same manner as described above. Is introduced.

  Further, as shown in FIG. 1, the subsequent construction of the overhang bridge body block is carried out by sequentially constructing the overhang bridge body blocks A2 to An from the opposite sides in the same manner as described above. Necessary design space portions are provided between the bridge body blocks An, and the space portions serve as main girders (center closing portions) of the central section. In this case, with respect to each overhanging bridge block constructed from both sides except the main girder of the central section, that is, the central closing portion, the arrangement of the sheaths 4a to 4n and the PC steel materials 5a to 5n to be added is as follows. Prestress is introduced into each of the stretched bridge body blocks A2 to An to fix the tension.

  Therefore, for the central closing part, when building the overhang bridge body block sequentially, from the upper surface of both overhang bridge body blocks An-1 immediately before the most advanced overhang bridge body block An on both sides, A plurality of sheaths 9 in which a PC steel material 8 is inserted in advance to the upper surface of the other overhanging bridge body block An-1 that penetrates the lower surface (bottom face) of the overhanging bridge body block An, respectively, are U-shaped. (Curved) placed and placed, the necessary rebars are placed in the spacing section, the formwork is assembled, and the cast-in-place concrete is cast to form the main girder of the central section, that is, the central closing part 10 To do. It should be noted that the PC steel material 8 is preferably inserted and disposed so as to be wrapped with the PC steel material 5 of the overhanging bridge body block over two sections, but if necessary, a plurality of overhanging bridges of one section or more. It can also be inserted through the body block.

  After the concrete of the central closing portion 10 is hardened, the PC steel material 8 is tension-fixed via the fixing member 6 similar to the above on the upper surface of one or the other overhanging bridge block An-1, thereby closing the central portion. Prestress is also introduced into the portion 10 (see FIG. 6), and a main girder connected in series with the extended bridge body block An between both side diameters is formed, and in particular, the front extended bridge block PC steel 8 is placed in a U-shape (curved shape) from the upper surface of An-1 to the overhang bridge block An and the bottom side (lower cross-section) of the central closure 10 to give tension and prestress. By doing so, the central closing part 10 which becomes a part of the main girder is supported from the lower surface side and is stabilized. Each of the overhang bridge body blocks A1 to An configured in this way is called a box girder having an internal space 11 at the center, and the upper portion 12 serving as a bridge surface is formed with a predetermined spread in the width direction. In addition, each of the overhang bridge body blocks A1 to An constructed by the PC steel material 5 which is a plurality of tension materials that apply prestress to the concrete is formed so that the entire thickness thereof is sequentially reduced.

  Next, a second embodiment shown in FIGS. 7 to 8 will be described. In this embodiment, only the means for introducing prestress into the central closing portion is different from that of the first embodiment, and the other configurations are the same. Is omitted. That is, the fixing part 13 of the closing part lower end PC steel material 8 is provided in the internal space 11 of the extension bridge body block An-1 on both sides immediately before the most advanced extension bridge body block An on both sides, respectively. A plurality of sheaths 9 through which the PC steel material 8 is inserted are provided between the portions 13 so as to penetrate the bottom surface of the overhanging bridge block An, and the end portions of the PC steel material 8 are placed with tension fixed by the fixing member 6. In addition, the necessary rebars are arranged in the space portion, the formwork is assembled, the cast-in-place concrete is cast to form the central closing portion 10 and connected to the overhanging bridge block An between the both side diameters in series. A connected main girder is formed. In addition, the cross section of the center closing part 10 is the same as FIG. 6 which concerns on the said 1st Embodiment.

  In the first and second embodiments, a plurality of overhanging bridge blocks A1 to An are sequentially connected to both ends of the head portion 3 of the bridge support base 1 one by one using cast-in-place concrete. It is constructed in a holding state, bridges are erected, PC steel materials 5, 5 a... 5 n provided on the upper surface side are tension-fixed at the end surfaces of the overhanging bridge body blocks A 1 to An, and both ends are stretched at the central closing portion 10. Pre-stress is also applied to the central closing part 10 by connecting the outgoing bridge body block An and fixing the PC steel material 8 disposed on the lower surface side of the central closing part 10 between the extended bridge body blocks An-1 on both sides. Therefore, the entire bridge including the overhanging bridge blocks A1 to An that become the main girder is in a strong and stable state.

  A third embodiment shown in FIGS. 9 to 10 will be described. In this embodiment, the first embodiment is used as it is, and a means for introducing prestress is further added to the central closing portion 10, and the other components are the same. A detailed description thereof will be omitted. That is, a plurality of sheaths 9a through which the PC steel material 8a is inserted in advance are disposed at substantially the same level position as the PC steel material 5 on the upper surface side of the most advanced overhang bridge body block An on both sides, and the overhang bridge is formed. Necessary reinforcing bars are arranged in the space between the body blocks An and a frame is assembled, and cast-in-place concrete is cast to form the central closing portion 10. After the concrete is hardened, the first embodiment is performed. As explained in the embodiment, the PC steel material 8 is tension-fixed on the upper surface of the both overhanging bridge body block An-1, and the end of the PC steel material 8a is fixed to the same fixing member 6 on the upper surface of the both overhanging bridge body block An. The tension is fixed, and prestress is introduced into the upper surface side and the lower surface side of the central closing portion 10, and the overhanging bridge block An between the both side diameters is firmly connected to form a main girder connected in series. It is. In this case, the PC steel material 8a disposed on the upper surface side of the central closing portion 10 is inserted and disposed in at least one overhanging bridge block, and is inserted through a plurality of overhanging bridge blocks. It can also be arranged.

  A fourth embodiment shown in FIG. 11 will be described. In this embodiment, the second embodiment is used as it is, and a means for introducing a prestress is further added to the central closing part 10, and the other components are the same. A detailed description thereof will be omitted. In short, in this embodiment, similarly to the second embodiment, the PC steel material 8a is preliminarily placed at the same level as the PC steel material 5 on the upper surface side of the most advanced overhanging bridge block An on both sides. As described in the second embodiment, after the plurality of inserted sheaths 9a are disposed and the concrete placed in the space between the overhang bridge body blocks An is hardened, both overhang bridges are used. In the internal space 11 of the body block An-1, the PC steel material 8 is tension-fixed, and the end of the PC steel material 8a is tension-fixed by the same fixing member 6 on the upper surface of the both overhanging bridge body block An, and the central closing is performed. Prestress is introduced into the upper surface side and the lower surface side of the portion 10, and the overhanging bridge block An between both side diameters is firmly connected to form a main girder connected in series. In addition, the cross section of the center closing part 10 is the same as the said FIG.

  In these 3rd and 4th embodiment, PC steel material 8a is arranged also on the upper surface side of central closure part 10 with respect to the 1st and 2nd embodiment, and it is a both overhang bridge body. This is common in that the connection with the block An is strengthened. As a result, the entire bridge, including the overhanging bridge blocks A1 to An that become the main girder, becomes strong and stable.

  A fifth embodiment shown in FIGS. 12 to 16 will be described. This embodiment is based on the segment construction method. That is, using the first embodiment as it is, the PC steel material is also applied to the lower surface side (bottom portion) of each of the extended bridge body blocks A1 to An constructed on both sides of the head 3 in the same manner as the upper surface side. Since they are disposed, the same parts as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted because it is duplicated. 12 to 15, similarly to the PC girder bridge according to the first embodiment, the head 3 and the overhanging bridge body block A1 constructed on both sides of the head 3 are covered with the sheath 4 on the upper surface side. And the PC steel material 5 are disposed, and a plurality of the same sheaths 14 are also disposed on the lower surface side, and the overhanging bridge block A1 allows the same PC steel material 15 to be inserted into the sheath 14 as a segment block, Both ends of the PC steel material 15 are fixed by tension at the end portions of the both overhanging bridge body blocks A1 in the same manner as the PC steel material 5 on the upper surface side by the fixing member 16 that also serves as a connection, and the head 3 and the overhanging bridge The body block A1 is integrated with prestress.

  In this way, the PC steel materials 5, 5a ... 5n, 15, 15a ... 5n are arranged on the upper surface side and the lower surface side, and the PC steel materials 5, 5a ... 5n, 15, 15a ... 15n are provided for each bridge block. Are connected via connecting tools 7 and 17 and are constructed by sequentially fixing the tension from the overhanging bridge block A2 to the most advanced overhanging bridge block An. 15 and can be constructed more quickly than the on-site concrete method, and the construction period is greatly shortened.

  And about the center closure part 10 between the most advanced overhanging bridge body blocks An of both sides, as demonstrated in the said 1st Embodiment, from the upper surface of the overhanging bridge body block An-1 of the one front side. The PC girder 8 is arranged in a U shape on the overhanging bridge block An and the bottom side of the central closing portion 10, and the main girder as shown in FIG. It is possible to firmly connect the central closing portion 10 which is a part of the.

  A sixth embodiment shown in FIGS. 17 to 18 will be described. This embodiment is based on the segment construction method. That is, using the second embodiment as it is, the PC steel material is also applied to the lower surface side (bottom portion) of each of the overhanging bridge blocks A1 to An constructed on both sides of the head 3 in the same manner as the upper surface side. Since they are arranged, the same parts as those in the second embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted because it is duplicated. In FIG. 17, as with the PC girder bridge according to the fifth embodiment, up to the overhanging bridge blocks A1 to An constructed on both sides including the head 3, the lower surface is the same as the upper surface. A plurality of sheaths 14, 14 a... 14 n and PC steel materials 15, 15 a... 15 n are disposed, and the end portions of the PC steel materials 15, 15 a. The tension is fixed by 16 and the head 3 and the bifurcated bridge body blocks A1 to An are prestressed and integrated. As shown in FIG. 18, the PC steel material 8 for applying prestress to the central closing portion 10 is one side before the overhanging bridge body block An as described in the second embodiment. The fixing member 13 is used to fix the tension to the fixing portion 13 provided in the internal space 11 of the overhang bridge body block An-1. In addition, the cross section of the center closing part 10 is the same as FIG. 16 which concerns on the said 5th Embodiment.

  In the fifth and sixth embodiments, the PC steel materials 5, 5a... 5n are provided on the upper surface side and the lower surface side of each of the overhanging bridge blocks A1 to An constructed on both sides of the head 3 using the segment method. , 15, 15a... 15n, and is common in that the tension is fixed on the end face of each overhang bridge block A1 to An, and each overhang bridge block A1 to An is constructed in a cantilever state. However, since strong prestress is applied to the entire cross section of each overhang bridge body block, the strength of the entire bridge is improved, and tensile stress is generated at the upper and lower ends of the cross section due to vibration loads such as large vehicles and wind. Even if it is canceled out, the entire bridge becomes strong and stable, and a great improvement in durability can be secured.

  A seventh embodiment shown in FIGS. 19 to 20 will be described. This embodiment is also based on the segment construction method. That is, using the third embodiment as it is, the PC steel material is also applied to the lower surface side (bottom portion) of each of the overhanging bridge body blocks A1 to An constructed on both sides of the head 3 in the same manner as the upper surface side. Since they are disposed, the same parts as those in the third embodiment are denoted by the same reference numerals, and detailed description thereof is omitted because it is duplicated. In FIG. 19, as with the PC girder bridge according to the fifth embodiment, up to the overhanging bridge block blocks A1 to An constructed on both sides including the head 3, the lower surface side is the same as the upper surface side. A plurality of sheaths 14, 14 a... 14 n and PC steel materials 15, 15 a... 15 n are disposed, and the end portions of the PC steel materials 15, 15 a. The tension is fixed by 16 and the head 3 and the bifurcated bridge body blocks A1 to An are prestressed and integrated. And, as described in the third embodiment, as shown in FIG. 20, the PC steel materials 8 and 8a for applying prestress to the central closing portion 10 are arranged on both the upper and lower surface sides. The tension is fixed.

  The eighth embodiment shown in FIG. 21 will be described. This embodiment is also based on the segment construction method. In other words, using the fourth embodiment as it is, the PC steel material is also applied to the lower surface side (bottom portion) of each of the overhanging bridge body blocks A1 to An constructed on both sides of the head 3 in the same manner as the upper surface side. Since they are arranged, the same parts as those in the fourth embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted because it is duplicated. In each of the overhang bridge blocks A1 to An constructed at both ends of the head 3, a plurality of sheaths 14, 14a... 14n and PC steel materials 15, 15a. The end portions of the PC steel materials 15, 15a ... 15n are tension-fixed by the fixing members 16 at the end surfaces of the overhanging bridge body blocks A1 to An, and the head 3 and the overhanging bridge body blocks A1 to A1. It is integrated by applying pre-stress up to An. And the PC steel materials 8 and 8a which give prestress to the center closing part 10 are arrange | positioned on both the up-and-down surface side, and are tension-fixed as demonstrated in the said 4th Embodiment.

  In these seventh and eighth embodiments, the PC steel material is arranged on the upper surface side and the lower surface side over the entire bridge including the central closing portion, and the tension is fixed for each overhanging block and prestressed. Therefore, the overall strength as a bridge can be greatly improved without using a steel frame, and the segment construction method can be applied.

  As described above, with the configuration described in each example, the overhang bridge body blocks A1 to An are tension-fixed by the PC steel material 5 for each block, and at the center closing portion 10, the PC steel material 8 is at least on the lower surface side. Since it is arranged and tension-fixed and prestress is applied to the cross section of the central closing portion 10, even if a tensile stress occurs in the cross section due to vibration load such as a large vehicle or wind, it is canceled out and the head of the bridge support base 1 The entire bridge including the overhang bridge body blocks A1 to An that become the main girder between the portions 3 is in a strong and stable state, and the improvement in durability can be ensured. In any of the above-described embodiments, the box girder-structured bridge has been described. However, the present invention is not limited to this and can be applied to any cross-sectional bridge girder. In addition, the extension bridge body blocks A1 to An can be constructed by tension fixation with PC steel materials 5, 15, 8, 8a, etc. without using steel frames. Can be reduced in weight, and is economical. Furthermore, in the invention according to the embodiment, a continuous girder bridge is illustrated, but it goes without saying that the invention can also be applied to a simple girder bridge.

  The PC girder bridge according to the present invention is a bridge girder constructed by a stretched bridge body block made of cast-in-place concrete by one section by an overhang construction method between bridge piers using a mobile work vehicle, For each section, the stretched bridge block is tensioned and fixed with the PC steel 5 to give prestress, and the stretched bridge block and the PC steel 5 are sequentially added so that the bridge is integrated continuously in the length direction. Constructed, PC steel material is also arranged in the central section that becomes the closing part of the span, prestress is applied, and the prestress is applied to the concrete of the entire main girder, so that it is excellent in strength A stable PC girder bridge can be obtained at low cost, and can be widely used for this kind of bridge.

DESCRIPTION OF SYMBOLS 1 Bridge support base 2 Bridge pier 3 Head 4, 4a-4n Sheath for PC steel materials on the upper surface side 5, 5a-5n PC steel materials on the upper surface side 6, 16 Fixing member 7, 17 Connector 8, 8a PC for central closing portion Steel 9, 9a PC steel sheath for central closure
10 Main section main girder (center closure)
DESCRIPTION OF SYMBOLS 11 Internal space 12 The upper surface used as a bridge surface 13 Fixing | fixed part 14, 14a-14n Sheath for PC steel materials 15 and 15a-15n on the lower surface side PC steel materials on the lower surface side A1-An Overhang bridge body block (main girder)
An-1 Overhang bridge block in front of the most advanced one

Claims (3)

A bridge girder constructed of overcast bridge body blocks made of cast-in-place concrete or segment blocks for each section by overhang construction method across the piers,
A concrete block formed by adding to each section is continuously constructed in the length direction,
The PC steel material is continuously arranged in the main girder cross section excluding the main girder of the central section that becomes the closing portion of the span, and the next section through the section and at least one adjacent section is penetrated at the lower section of the central section. PC steel material is arranged in a curved shape over the upper surface side or lower surface side of the overhang bridge body block of the section,
The PC girder bridge structure is characterized in that prestress is applied to the concrete of the main girder by tension-fixing the PC steel material of the main girder cross section and the PC steel material arranged at the lower part of the main girder cross section of the central section. . PC steel continuously arranged in the main girder cross section excluding the main girder of the central section that becomes the closed portion between the diameters is disposed on the upper surface side or the upper surface side and the lower surface side of the main girder cross section, and the PC The PC girder bridge structure according to claim 1, wherein the steel material is tension-fixed for each predetermined section and prestress is introduced into the main girder. PC steel material is arranged over the upper surface of the overhanging bridge body block of the adjacent section through the upper section of the main girder section of the central section serving as the closing portion, and the tension is fixed on the upper surface of the adjacent section. The PC girder bridge structure according to claim 1 or 2.

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