JPH0784724B2 - Mounting method of anchor bar for continuous girder structure - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to a method of attaching an anchor bar to a continuous girder structure such as a continuous girder bridge having a large number of continuous lower structures and having a prestressed concrete upper structure. It is a thing.

[Prior art]

In many girders, such as continuous girder bridges of prestressed concrete, that is, in continuous girder structures with substructures,
When the horizontal force during an earthquake in the bridge axis direction is received by only one substructure as a fixed fulcrum, a large horizontal force concentrates only there, making design difficult, and if multiple points are fixed, The rigidity of the substructure causes internal stress due to displacement such as temperature, drying shrinkage, and creep, so not only in the design of the pier, that is, the substructure, but also in the design of the bridge girder, that is, the superstructure. This will cause problems.

Therefore, as a means to solve this type of problem in the past, by softly connecting the upper structure and the lower structure in the bridge axial direction, the above internal stress is relieved and the horizontal force during an earthquake in the bridge axial direction is reduced. As for the above, a method of supporting each substructure in a dispersed manner is adopted.

As this method, there is a method using a natural rubber bearing and utilizing shear deformation due to prestress, but this is to burn steel material on the upper and lower surfaces of natural rubber and fix it to the upper structure and the lower structure respectively, Not only is the construction cost high, but because the horizontal reaction force is distributed using a rubber shear spring, the amount of movement during an earthquake is large, so a large expansion joint is required. Since the structure is also deformable with respect to, there is a problem that the bearing is twisted.

Another method using a viscous stopper is to form the soft bond by the effect of a viscous material, but since the viscous mechanism is provided in the lower structure, elastic deformation due to prestress of the upper structure The amount of deformation, the amount of deformation due to temperature, creep, drying shrinkage, and the amount of deformation due to earthquake must all be taken into consideration when setting, so that the amount of deformation becomes a large value, and thus a large mechanism is required.

[Object of the Invention]

The present invention solves the above-mentioned conventional problems, and can disregard the horizontal movement amount due to prestress in a continuous girder structure of prestressed concrete having a large number of continuous lower structures. It is an object of the present invention to provide a method of attaching an anchor bar of a continuous girder structure that can evenly distribute force to each substructure.

[Structure of Invention]

The method for attaching the anchor bar of the continuous girder structure of the present invention for achieving the above object is such that the upper structure of the prestressed concrete is pre-stressed, and the upper part of the anchor bar is fixed to the lower structure. It is characterized by positioning in the superstructure and then placing concrete on the upper part of the anchor bar, and positioning in the superstructure with prestressed concrete prestressed concrete. The upper part of the anchor bar to be performed is set in the cap with an elastic body interposed in the bridge axis direction.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.
The figure is a side view of a cross section of a main part showing a continuous portion between an upper structure and a lower structure of a continuous girder bridge of prestressed concrete to which the method for attaching an anchor bar of a continuous girder structure of the present invention is applied,
2 is an enlarged front sectional view of FIG. 1, and FIG. 3 is A- of FIG.
Main part enlarged plan sectional view of the anchor bar in the A direction, FIG. 4 is an overall side view of the prestressed concrete continuous girder bridge of FIG. 1, FIG. 5 is an explanatory view of the construction order of the continuous girder bridge of FIG. 4, 6, 7 and 8 are explanatory views for removing the box of the upper structure at the time of setting the anchor bar of FIG. 1, FIG. 6 is its front sectional view, and FIG. 7 is the side of FIG. FIG. 8 is a sectional view and FIG. 8 is a plan view of an essential part of FIG.

First, in this embodiment, as a continuous girder structure, as shown in FIG. 4, a continuous girder bridge having a plurality of lower structures 2 continuous with an upper structure 1 of prestressed concrete is shown. The upper structure 1 and the lower structure 2 thereof are shown. As shown in FIG. 2, a slide bearing 3 which is freely movable in the bridge axis direction of the bridge is interposed between the slide bearing 3 and the bridge structure. The slide bearing 3 is compressed from the superstructure 1 against the vertical reaction force. It has a structure in which only a plurality of anchor bars 4 fixed to the lower structure 2 are used to restrain and fix only the force that acts on the bridge structure.

Next, in the lower structure 2, as shown in FIGS.
The lower part of each anchor bar 4 is fixed, and the upper part of the anchor bar 4 is set in a rectangular cap 6 with an elastic body 5 such as neoprene interposed in the bridge axis direction as shown in FIG. Therefore, with respect to the deformation of the bridge in the axial direction of the bridge, such as creep, and dry shrinkage, the compression spring force of the elastic body 5 interposed between the anchor bar 4 and the cap 6 is utilized. The horizontal reaction force acting on the lower structure 2 can be alleviated, and by further limiting the space such as the gap 7 in the cap 6 provided for each lower structure 2 at each fulcrum, the horizontal level at the time of earthquake The force can be distributed to each substructure 2.

Further, the cap 6 is provided in the upper structure 1, and a box removing box 8 as shown in FIGS. 6, 7 and 8 is provided around the installation position of the cap 6 in the upper structure 1,
The amount of deformation due to pre-stress during construction can be ignored by adopting the method of preserving the elastic deformation of pre-stressed concrete during pre-stress construction. Can be small.

As the above-mentioned construction order, the dimensions are determined in consideration of the amount of deformation due to creep and drying shrinkage, that is, the amount of horizontal movement, for each fulcrum position of each substructure 2, and as shown in FIG. An elastic body 5 having a gap 7 consisting of a hole is set at the front and rear of the anchor bar 4 in the bridge axis direction, and the anchor bar 4 is set at a mounting position by a fixing bolt (not shown). After fixing to the lower structure 2, concrete is poured up to the upper edge of the cap 6.

This is to prevent the set position of the cap 6 from shifting due to concrete pouring, and to remove the bolt for fixing the cap 6 provided for positioning on the upper portion of the anchor bar 4.

Next, after the concrete has hardened, remove the bolts and return the superstructure 1 to a state where it can move freely in the bridge axis direction, and then place concrete in the remaining part of the box opener 8 to set the prestress. To finish.

At the position where the anchor bar 4 is in contact with the inside of the cap 6 and the anchor bar 4, in order to improve the sliding, a sliding process such as Teflon (registered trademark) 9 is performed as shown in FIG.

Furthermore, the thickness and pre-deformation amount of the elastic body 5 provided at the fulcrum position of each substructure 2 should be determined by calculation in consideration of the deformation amount due to the creep and drying shrinkage of the concrete to be placed, that is, the movement amount. Thereby, the amount of deformation of the elastic body 5 at each fulcrum position can be made equal when the construction is completed.

Therefore, when a horizontal force is applied during an earthquake, the amount of deformation of the elastic body 5 becomes the same amount, so that the horizontal force is evenly distributed to each fulcrum of each substructure 2.

It should be noted that FIGS. 6, 7, and 8 show a box opener 8 of the superstructure 1 provided for positioning the upper portion of the anchor bar 4 in the superstructure 1, and the box opener 8 is the superstructure. It is carried out to the digit of 1 and after the prestressing of all the diameters is introduced, the 8 parts of the box are filled with concrete.

Further, FIG. 5 shows a construction sequence from the primary construction to the completion of the sixth construction when the superstructure 1 is divided into a plurality of substructures 2 of the continuous girder bridge and is indicated by P ₁ . In the lower structure 2, a temporary bearing 10 is provided, and in the sixth construction, pre-stress is tensioned and then concrete is placed in each box punch 8 portion.

Next, the operation of the method for attaching the anchor bar of the continuous girder structure of prestressed concrete of the present invention described above will be described. Generally, the horizontal reaction force acting on the lower structure 2 is prestress, creep, dry shrinkage, and Although it occurs due to inertial force during an earthquake, in the method of the present invention, the horizontal movement amount of the substructure 2 caused by prestress is considered from the beginning at the time of construction, so that there is no effect of prestress after construction. Regarding the horizontal reaction force due to the horizontal movement caused by the creep and the dry shrinkage that occur after the construction, the cap 6 in which the elastic body 5 is interposed in the front and rear of the anchor bar 4 in the bridge axial direction is provided in the upper structure 1. By being provided, the amount of movement associated with the horizontal reaction force in each lower structure 2 is reduced.

Further, in this case, a box opener 8 for locating the cap 6 is provided on the upper structure 1 side, and the upper portion of the anchor bar 4 fixed to the lower structure 2 is projected into the cap 6 via an elastic body 5. Therefore, since the prestress is applied to the superstructure 1, the movement amount due to the prestress in the horizontal reaction force generated by the movement of the superstructure 1, that is, the elastic deformation amount is taken into consideration in this continuous girder bridge. It has already been done at the time of construction.

Therefore, the amount of horizontal movement due to the remaining creep and drying shrinkage is absorbed by the action of the elastic body 5 which is interposed in the cap 6 from which the anchor bar 4 is projected so as to have a predetermined gap in the cap 6. .

〔The invention's effect〕

As described above, if the method of attaching the anchor bar of the present invention is applied to the continuous girder structure of prestressed concrete, the horizontal movement amount due to prestress during construction can be ignored, and creep and superstructure in the superstructure after construction and There is an effect that the horizontal reaction force generated by the drying shrinkage can be relaxed.

Further, if the method of the present invention is adopted, the construction cost of the substructure will be low, the amount of movement to each fulcrum at the time of an earthquake will be small, the design of the substructure will be easy, and the safety will be high. effective.

[Brief description of drawings]

FIG. 1 is a side view of a cross section of a main part showing a connecting portion between an upper structure and a lower structure in an embodiment of a continuous girder bridge of prestressed concrete to which the anchor bar attaching method for a continuous girder structure of the present invention is applied, The figure is an enlarged front sectional view of Fig. 1, Fig. 3 is an enlarged plan sectional view of the main part of the anchor bar in the AA direction of Fig. 1, and Fig. 4 is the entire continuous girder bridge of prestressed concrete of Fig. 1. FIG. 5 is a side view, FIG. 5 is an explanatory view of the construction order of the continuous girder bridge of FIG. 4, FIG. 6, FIG. 7, and FIG.
FIG. 6 is an explanatory view for removing the box of the upper structure when the anchor bar is set, FIG. 6 is a plan sectional view thereof, FIG. 7 is a side sectional view of FIG. 6, and FIG. 8 is a main part of FIG. It is a top view. 1 ... Upper structure, 2 ... Lower structure, 4 ... Anchor bar, 5 ... Elastic body, 6 ... Cap, 8 ... Unboxed.

Claims (2)

[Claims] 1. An upper part of an anchor bar having a lower part fixed to a lower structure is positioned in the upper structure while prestressing is introduced into the upper structure of the prestressed concrete,
Then, a method of attaching the anchor bar of the continuous girder structure, in which concrete is placed on the upper part of the anchor bar. 2. A continuous method of setting the upper part of an anchor bar for positioning in the superstructure of prestressed concrete in a state in which prestress is introduced into the cap with an elastic body interposed in the bridge axial direction. How to attach the anchor bar of the girder structure.