JP4413765B2 - Pre-tension hollow girder horizontal fastening PC steel temporary fixing device and fixing method - Google Patents

Description

  The present invention relates to a temporarily fixing fixing device and fixing method for a PC steel material that is laterally tightened for a preten hollow beam.

  In highway viaducts constructed on relatively flat sites, a pre-tensioned precast concrete bridge manufactured as a factory product is transported to the site and built by a truck crane or the like. The advantages of this precast method are that a product with stable quality can be obtained, and economic advantages such as shortening the construction period and saving labor.

  On the other hand, regarding the cross-sectional structure of a precast concrete bridge girder, there are a T-shaped cross-section preten girder (hereinafter referred to as T girder) and a hollow cross-section (hollow) girder (hereinafter referred to as hollow girder). The T-girder has a high center of gravity due to its cross-sectional shape and is slightly less stable during transportation and erection, while the hollow girder has a stable cross-sectional shape without fear of rollover. There is a lot to be done.

  When building bridges with hollow girders, joint gaps are formed between the girders, so it is necessary to place non-shrink mortar, cast-in-place concrete, etc. (hereinafter abbreviated as concrete) in the joint gaps. When placing concrete, the lateral pressure exerts a force that pushes the gap between adjacent hollow girders and displaces the girders. In order to prevent the above-mentioned side pressure, the concrete between the girders is placed in a state in which tension is applied to the laterally tightened PC steel material that is disposed through the hollow girders in the direction perpendicular to the bridge axis.

  That is, the hollow girder has a hollow cross section except that solid cross-section portions (horizontal girder) are arranged at predetermined intervals at the longitudinal end portion and the intermediate portion. PC steel materials for lateral fastening are placed through the bridge axis at right angles, and both ends of the PC steel materials are fixed to the hollow girders on both sides to integrate the adjacent girders. By introducing tension to the steel material, it is prevented that the adjacent hollow beams are expanded by the side pressure of the filler placed in the gap between the beams.

  3 and 4, FIG. 4 is a plan view of a partial cross section of a hollow girder bridge, and FIGS. 3A and 3B are cross-sectional views taken along lines AA and BB in FIG. 4. . As shown in each figure, the bridge 1 of the hollow girder bridge has a girder structure in which a plurality of hollow girders 2 are arranged in a direction perpendicular to the bridge axis (the width direction of the road). The hollow girder 2 has a solid cross-sectional portion (horizontal girder) 3 arranged at predetermined intervals at the end and intermediate portion in the longitudinal direction, and the other is a cross-sectional structure of the hollow portion 4. In order to integrate each hollow girder 2, the cross-section PC steel material 7 is passed in the upper and lower sections of the cross section (horizontal girder) 3 and in the direction perpendicular to the bridge axis, and then between the girder in the joint gap 5 between the hollow girders. Before the concrete 6 is placed in order to prevent the hollow beam 2 from being displaced and displaced due to the lateral pressure caused by the concrete 6 being cast, the space between adjacent hollow beams spreads. Furthermore, the tension force of the strength that the hollow girder 2 is not displaced by the lateral pressure of the inter-girder concrete 6 is introduced into the laterally tightened PC steel material 7.

  More specifically, when a plurality of hollow girders 2 are arranged side by side by preliminarily forming a sheath 8 by penetrating the solid cross-sectional portion 3 of the hollow girder 2 in a direction perpendicular to the bridge axis, Since the bridges communicate in the direction perpendicular to the bridge axis, the PC steel material 7 is inserted into the sheath 8 to fix the end. That is, the laterally tightened PC steel material 7 is pulled out from the side of the hollow beam 2 arranged on both sides through the hole 11 of the anchor plate 10, and further passed through the female cone 12 of the fixing grip 14 to be wedged in the female cone 12. By tightening the laterally tightened PC steel material 7 with the member 13, both end portions of the laterally tightened PC steel material 7 are fixed to both side portions of the hollow girder 2.

After fixing the end of the PC steel material 7 that was tightened and tightened so that the hollow beam 2 would not move due to the lateral pressure of the inter-girder concrete 6, the inter-girder concrete 6 was placed in the joint gap 5 between the hollow beams. To cast. Then, after the concrete is hardened, the fixing grip 14 of the laterally tightened PC steel material 7 is once removed, and then the original prestress is introduced into the laterally tightened PC steel material 7 using a tensioning device. For example, Japanese Patent Laid-Open No. 10-12148 discloses a related art related to a hollow girder.
Japanese Patent Laid-Open No. 10-12148

  In a pre-tension hollow girder bridge, before tightening the laterally tightened PC steel material that has been inserted in the direction perpendicular to the bridge axis, cast concrete between the girder gaps and confirm the predetermined strength, and then tighten the side The original prestress is introduced into the PC steel and integrated with the hollow girder. In other words, the PC steel is not strained at the time of placing the interstitial concrete, and therefore, the lateral pressure is applied to the hollow girder by the pressing force of the interstitial concrete, causing the girder to move and cause unnecessary displacement (deformation). The reason why the PC steel material is not tensioned at the time of placing the interstitial concrete is mainly because it takes time to remove the fixing grip once in order to introduce the original prestress of the PC steel material which is laterally tightened in the subsequent process.

  In other words, before placing concrete between girders, if a tension force that does not cause unnecessary deformation (displacement) to the girders due to the side pressure of the concrete is applied to the laterally tightened PC steel, Because the force that pushes between the girders acts, the PC steel is applied with a force that exceeds the initial tension, and the wedge member is tightly tightened in the female cone of the fixing grip. To remove it from the steel material, a large device such as a jack is required. For this reason, there has been a problem that it takes a long time and wasteful labor to remove the fixing grip.

  In order to avoid the above-mentioned problem, in consideration of the ease of removing the fixing grip, before placing the inter-girder concrete, the laterally tightened PC steel material is stretched as straight as possible so that there is no slack. In addition, it is often the case that the interstitial concrete is placed by placing a fixing grip on the end of the PC steel as usual without applying too much tension to the PC steel. However, in this case, even if the PC steel is straightened, there is still a lot of slack in reality, and because the slack is extended by the lateral pressure due to the placement of concrete between the girders, the deformation (displacement) of the hollow girder cannot be prevented. There was a problem that the digit shifted from the correct position.

In the present invention, by installing a temporary fixing fixture that can be expanded and contracted in the length direction in front of the fixing grip at the end of the laterally tightened PC steel material, Even when sufficient tension is applied, the fixing grip can be smoothly removed after the concrete between the girders is hardened.

  In order to achieve the above object, the present invention is configured as follows.

The first invention is a hollow girder bridge, in which a transversely tightened PC steel material is inserted through a solid cross section of the hollow girder in a direction perpendicular to the bridge axis, and the anchor plate and the fixing grip in the laterally tightened PC steel material pulled out from the hollow girder, It features a pre-fixed hollow girder PC fastening temporarily fixing fixing device that is fitted with a temporary fixing fixing jig that is formed by screwing a sleeve with an external thread with a nut and a sleeve with an internal thread. .

According to a second aspect of the present invention, in the hollow girder bridge, there is provided a laterally tightened PC steel material that allows the solid cross-section portion of the girder to be inserted in a direction perpendicular to the bridge axis. A temporary fixing fixing jig configured by screwing a sleeve with an outer thread with a nut and a sleeve with an inner thread cut into between is fitted, and the length of the temporary fixing jig is turned by turning the sleeve. After setting the fixing grip on both ends of the PC steel material with the shortest setting, rotate the sleeve in the opposite direction to extend the length of the temporary fixing jig to remove the slack of the PC steel material After the concrete between the girders is placed and the concrete is hardened, turn the sleeve in the opposite direction to shorten the length of the temporary fixing jig and remove the fixing grip. It features a wearing method.

According to the present invention, before placing the inter-girder concrete in the hollow girder, fixing is performed with the length dimension of the temporarily fixing fixing jig fitted to the laterally tightened PC steel material between the anchor plate and the fixing grip set to the shortest. Set the grip. After that, by extending the length of the temporary fixing jig to the maximum, it is possible to remove the slack of the laterally tightened PC steel, and the hollow girder can be tightened with an appropriate tension. When placing concrete between hollows, the hollow girders do not move and can be placed smoothly. When the fixing grip is removed once in order to introduce the original pre-stress to the laterally tightened PC steel after hardening the interstitial concrete, the length of the temporary fixing fixing jig is shortened so that the female cone is a wedge member. It is possible to move in the direction away from (i.e., the anchor plate direction). Accordingly, the wedge member can be easily detached from the female cone by moving the female cone in this direction, and the work of removing the fixing grip from the laterally tightened PC steel is facilitated.

  Embodiments of the present invention will be described below with reference to the drawings. In addition, the same code | symbol is attached | subjected and demonstrated to the same element as the prior art example shown in FIG. 3, FIG.

  1 (a) and 1 (b) are an exploded sectional view and an assembled side view of a temporarily fixed fixing jig installed on a horizontal steel PC material of a hollow frame in a preten hollow girder bridge, and FIG. A sectional view showing a state in which the length is expanded and contracted is shown, in which (a) shows a state in which the temporarily fixing fixing jig is extended, and (b) shows a shortened state.

  In each drawing, a temporary fixing fixing jig 15 is a sleeve (hereinafter referred to as an outer screw sleeve) having a predetermined length dimension in which a nut 16 is joined to a sleeve end portion by welding 17 and an outer screw 18 is cut on an outer periphery. ) 19 and a sleeve 21 (hereinafter referred to as an internal screw sleeve) 21 in which an internal screw 20 is screwed so as to be able to advance and retract freely. Both sleeves 19 and 21 are arranged between the anchor plate 10 and the fixing grip 14 provided on the laterally tightened PC steel material 7 so that the nut 16 contacts the side surface of the anchor plate 10 and fits into the laterally tightened PC steel material 7. Are combined. By rotating these outer screw sleeve 19 and inner screw sleeve 21 to advance or retract the threaded portion, the axial length of both sleeves 19, 21, that is, the length dimension (L) of the temporary fixing fixing jig 15. Can be stretched or shortened. The fixing grip 14 includes a female cone 12 and a wedge member 13.

  The use form of the temporary fixing fixing jig 15 will be described with reference to FIG. A bridge 1 is constructed with a plurality of hollow girders 2 arranged, and before the concrete 6 between the girders is placed in the joint gap 5 between the hollow girders 2, the PC steel 7 is laterally tightened through the sheath 8 in the direction perpendicular to the bridge axis. It is the same as in the prior art that it is installed and pulled out from both sides of the hollow beam 2 (see FIGS. 3 and 4). In this embodiment, as shown in FIGS. 2 (a) and 2 (b), the holes of the anchor plate 10 are drawn out from the both sides of the hollow beam 2 and the anchor plate 10 is applied to the side surface of the hollow beam 2 as shown in FIGS. 11, and a temporary fixing fixing tool 15 including an outer screw sleeve 19 and an inner screw sleeve 21 is fitted to the laterally tightened PC steel material 7, and further, the laterally tightened PC steel material 7 is fixed to the female cone 12 of the fixing grip 14. And shows a state in which the outer periphery of the PC steel material is tightened by the wedge member 13 installed in the female cone 12. In the above arrangement mode, the nut 16 welded to the end of the outer screw sleeve 19 is arranged so as to contact the outer surface of the anchor plate 10, and the inner end of the female cone 12 and the inner screw sleeve 21 are arranged. Set so that the outer edge abuts.

  In FIG. 2A, a tool is fitted to the nut 17 to stop the rotation of the outer screw sleeve 19, and the inner screw sleeve 21 is fully turned and screwed. The length (L) of the temporary fixing fixing jig 15 is the shortest. The mode set so that it may become length is shown. Since the inner screw sleeve 21 is provided with a tool insertion hole 22, the tool can be easily inserted into the hole 22 and rotated. After setting the length of the temporary fixing jig 15 to the shortest length (L), the fixing grip 14 is set to the end of the laterally tightened PC steel material 17.

  After the temporary fixing fixing jig 15 and the fixing grip 14 are laterally tightened and set on the PC steel material 7, the inner screw sleeve 21 is turned in the opposite direction so that the length (L) of the temporary fixing fixing jig 15 is maximized. Operate to As a result, the side fastening PC steel material 7 can be tensioned to remove sagging, and the hollow girder 2 can be tightened with an appropriate tension force while the side fastening PC steel material 7 is straight.

  Next, interstitial concrete 6 is placed in the joint gap 5. At this time, the joint gap 5 is widened by the side pressure of the inter-girder concrete 6 and the hollow girder 2 tends to shift. However, by extending the temporary fixing fixing jig 15, the side-tightened PC steel material 7 is removed to the extent that sagging is removed. Since the hollow girder 2 is moderately tensioned, the hollow girder 2 does not move and does not have a problem that the inter-girder concrete 6 leaks from the joint gap, and can be placed smoothly and quickly. Note that when placing the interstitial concrete 6, care is taken so that the concrete does not enter the sheath in the joint gap.

  In order to remove the fixing grip 14 from the PC steel material 7 after the interstitial concrete 6 has hardened, the inner screw sleeve 21 is turned in the opposite direction to shorten the length dimension (L) of the temporary fixing jig 15. . As a result, the female cone 12 can be moved in a direction away from the wedge member 13 (that is, the direction of the anchor plate 10). Therefore, the female cone 12 is moved in this direction, and the wedge member is moved from the inside of the female cone 12. 13 can be easily detached, and thus the fixing grip 14 can be easily removed from the laterally tightened PC steel material 7.

Note that the nut 16 provided in the outer screw sleeve 19 and the tool insertion hole 22 provided in the inner screw sleeve 21 are means for facilitating the efficient rotation of the sleeves 19 and 21, and other tool engagements. Means may be provided.

(A) and (b) are an exploded cross-sectional view and an assembled side view of a temporary fixing fixing jig installed on a PC steel material of a laterally tightened hollow girder in a preten hollow girder bridge. Sectional drawing which shows the state which expands / contracts the length dimension of a temporary fixing fixing jig is shown, (a) shows the state which the temporary fixing fixing jig extended, (b) shows the shortened state. (A) and (b) are AA sectional drawing and BB sectional drawing of FIG. It is a top view of a partial cross section of a hollow girder bridge.

Explanation of symbols

1 Hollow girder bridge
2 Hollow girder 3 Solid section (horizontal girder)
4 Hollow part 5 Joint gap 6 Girder concrete 7 Horizontally tightened PC steel 8 Sheath 10 Anchor plate 11 Hole 12 Female cone 13 Wedge member 14 Fixing grip 15 Temporary fixing jig 16 Nut 17 Welding 18 External screw 19 External screw sleeve 20 Internal Screw 21 Internal thread sleeve 22 Tool insertion hole

Claims (2)

  For hollow girder bridges, laterally tightened PC steel material that passes through the solid cross section of the hollow girder in the direction perpendicular to the bridge axis is provided, and a nut is provided between the anchor plate and anchoring grip in the laterally tightened PC steel material drawn from the hollow girder A pre-fixed hollow girder PC temporarily fixed fixing device characterized in that it is fitted with a temporary fixing fixing jig formed by screwing a sleeve with an external thread and a sleeve with an internal thread.   For hollow girder bridges, a laterally tightened PC steel material is inserted through the cross section of the girder in the direction perpendicular to the bridge axis, and a nut is attached between the anchor plate and the fixing grip in the laterally tightened PC steel material pulled out from the hollow girder. A temporary fixing fixing jig constituted by screwing a threaded sleeve and an inner threaded sleeve is fitted, and the length of the temporary fixing jig is set to the shortest by turning the sleeve, and After setting the fixing grips on both ends of the PC steel material for side fastening, turn the sleeve in the opposite direction to extend the length of the temporary fixing jig to remove the slack of the side fastening PC steel material, and then cast concrete between the girders. After the concrete has hardened, the sleeve is turned in the opposite direction to shorten the length of the temporary fixing jig, and the fixing grip is removed. Fixing method.

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