JP2015151768A5 - - Google Patents

Description

Replacement method of concrete floor slab for elevated road and replacement PC floor slab by the same method

  The present invention relates to a method for replacing a concrete floor slab for an elevated road in a steel girder bridge mainly composed of a steel girder and a concrete floor slab, and a replacement PC floor slab by the method.

  In general, a concrete slab in a steel girder bridge is a structural member that directly supports a vehicle, and is directly affected by an increase in vehicle traffic and an increase in the size of the vehicle, and there are many cases of damage requiring replacement. In addition, there are many cases of salt damage deterioration due to corrosion of steel in concrete due to the application of antifreezing agents in cold regions and the influence of incoming salt from the ocean.

Conventional, repair method as a countermeasure to the damage of the concrete slab, such as described above is widely developed, as fundamental measures, there is a Ru method sort take a concrete floor slab.

As take sort method of the concrete slab, after removing the existing floor slab, mold, assemble the rebar, and Da設the concrete and how to build a new reinforced concrete floor slab, after removing the existing floor slab There are methods (for example, Patent Documents 1 and 2) in which precast prestressed concrete slabs (hereinafter referred to as PC slabs) are installed side by side and new PC floor slabs are installed. However, these construction methods simultaneously replace the entire width of the road. Therefore, the road becomes unusable in all widths, and the road must be closed during the construction period, which worsens the traffic situation of the road.

As a method for solving this problem, the replacement takes a concrete slab, road divided width direction and the primary construction unit and the secondary construction unit, while being continued sharing of secondary construction section, of the primary construction unit There is a method of constructing a replacement work, and after completing the replacement of the primary construction part, sharing this as a road, and then performing the replacement of the remaining secondary construction part.

  More specifically, as shown in FIG. 6A, in the state where the entire width of the road on the concrete slab 1 is shared, it is temporarily supported on the lower surface of the cutting position 2 for dividing into two in the width direction. Girder 3 is installed. The temporary support beam 3 is supported by horizontal beams 5 and 5 supported by adjacent main steel beams 4 and 4.

  Next, as shown in FIG. 6 (b), the existing floor slab of the primary construction part 6 is removed in a state where the secondary construction part 7 at the cutting position 2 is shared, as shown in FIG. 6 (c). The precast PC plate 8 in which the floor slab 1 is halved is installed on the removed part.

It was then shared on a floor plate made of precast PC Version 8 newly laid as shown in FIG. 7 (d), to remove the existing deck of the remaining secondary construction part 7 of the non-taken replacement, accordingly As shown in FIG. 7E, the remaining half-split precast PC plate 9 is installed on the removed portion, and the floor plate 10 is formed by connecting the two floor plates 8 and 9 together. Thus, there is a method of completing the replacement and sharing the entire width as shown in FIG.

JP 2007-239365 A JP 2009-264040 A

  In the conventional method described above, the floor slab 10 in which a plurality of precast PC plates 8 and 9 are connected and integrated in the width direction is configured, but simply by joining the precast PC plates 8 and 9 together. As shown in FIG. 8, the prestress distribution is such that no prestress is introduced into the joint side end portions of the precast PC plates 8 and 9, and the desired prestress is 100% effective at the end portions. This is from a position retracted by a certain length from.

  For this reason, conventionally, as shown in FIG. 9, a method of welding the reinforcing bars 11, 11 of each precast PC plate 8, 9, or a PC steel rod 12 straddling both precast PC plates 8, 9 as shown in FIG. 10. 11 and 12, as shown in FIG. 11 and FIG. 12, the arc-shaped PC tension material insertion hole 13 is formed so as to straddle both the precast PC plates 8 and 9 and both ends are opened on the lower surface of each precast PC plate. There is a method in which the PC strand 14 for connection is passed through this, and the connection is made by tensioning the PC strand 14.

  Among these conventional methods, in the methods shown in FIGS. 9 and 10, since prestress is not introduced into the precast PC plate joining portion, it is essential to leave the temporary holding beam 3 as it is, as shown in FIGS. Even when tension is applied by the PC strand, if the PC strand 14 is short as shown in FIG. 11, there is a problem that the elongation allowance at the time of tension is insufficient and it is difficult to introduce sufficient prestress.

As shown in FIG. 12, if the length of the PC strand 14 is a length necessary for introducing prestress, the prestress due to the PC tension material for the full width of each precast PC plate is provided at the end of each pretension precast PC plate 8.9. In other words, a portion where prestress due to the PC strand for connection is introduced is generated, which is uneconomical.

  Furthermore, when the precast PC plates 8 and 9 are connected and used, the PC tension material for introducing the prestress must be fixed at both ends of each precast PC plate, and thus requires a large amount of hardware for fixing. Since this hardware is an important part for the introduction and maintenance of prestress, it must be expensive because of its high quality in terms of material, dimensional accuracy, etc. There was a problem of greatly affecting replacement costs.

  In view of such a conventional problem, the present invention divides an existing floor slab into a plurality of road width directions and leaves the common part, and replaces the other part with a concrete construction for elevated road by split construction. In this replacement method, pre-stress is introduced between the divided parts of the new concrete floor slab after completion of the replacement work in a continuous state, and the floor slab is connected with the conventional pre-tension precast PC plate. The purpose of the present invention is to provide a method for replacing a concrete floor slab for an elevated road and a replacement floor slab that can be constructed at a low cost as compared with the case where it is configured.

  The feature of the invention described in claim 1 for achieving the above object is that the road width direction of the existing concrete floor slab for a plurality of lanes supported by a plurality of bridge girders installed in the road length direction is the primary construction section. Set up the replacement section divided into the secondary construction section, leave the secondary construction section in a state that can be shared as a road, replace the primary construction section adjacent to this, and replace the primary construction section after the replacement In the method of replacing a concrete floor slab for an elevated road that is shared with the primary construction section and shared as a road after the secondary construction section is replaced after being shared as a road, For replacement, the existing concrete floor slab of the primary construction section is removed, and a pre-tensioned precast PC slab pre-stressed in the width direction is installed on the removed primary construction section, and a new copy is added to the primary construction section. After building a cleat slab and sharing the new concrete floor slab of the primary construction section as a road, the existing concrete floor slab of the secondary construction section is removed, and the concrete floor slab is removed to the removed secondary construction section. Is inserted into the concrete floor slab and the end of the pre-tensioned precast PC plate installed in advance, and a PC tendon is inserted into the concrete floor slab by tensioning the PC tendon. In addition to providing a PC floor slab by applying stress, a PC floor slab in which the PC floor slab and the pretension precast PC plate are integrated is used.

  The feature of the invention described in claim 2 is that, in addition to the configuration of claim 1, prior to the removal of the existing concrete floor slab of the primary construction part, a temporary support material is installed under the edge of the secondary construction part. .

  The invention according to claim 3 is characterized in that, in addition to the structure of claim 1 or 2, the temporary support material is provided below the edge of the new pretension precast PC plate installed in the primary construction part on the secondary construction part side. Is to install.

  According to a fourth aspect of the present invention, in addition to the configuration of the second or third aspect, the temporary support member is provided both below the edge of the existing concrete floor slab and below the edge of the pretension precast PC plate adjacent thereto. The purpose is to use a common steel girder for temporary support.

  The feature of the invention described in claim 5 is that prestress is introduced in the entire width direction of the concrete floor slab for the elevated road, and is composed of a primary construction part and a secondary construction part that divide the width direction into two parts, The primary construction part is constituted by arranging and supporting a number of pretensioned precast PC plates prestressed by a pretension method in the length direction of the steel beam, and the secondary construction part of the pretensioned precast PC plate A tension supporting portion is provided on the back surface of the side end portion, and the secondary construction portion is constituted by a post tension PC post tension PC plate, and the pre-tension precast PC plate includes a post tension PC plate side. A PC tension material insertion hole that is open to communicate with the end face and the tension bearing portion is formed, and the post tension PC Includes a PC tension material insertion hole that is open to the end surface on the side of the pretension precast PC plate and the opposite end surface thereof, and the PC tension for post tension that is continuously inserted through both the PC tension material insertion holes. By tensioning the material, the pre-stress PC plate prestress is introduced, and the pre-tension precast PC plate and the post-tension PC plate are integrated into an elevated road replacement PC floor slab.

  In the present invention, as described in claim 1, the replacement of the primary construction part is performed by removing the existing concrete floor slab of the primary construction part and prestressing the removed primary construction part in the width direction. The pre-tensioned precast PC slab provided is constructed, a new concrete floor slab is constructed in the primary construction section, the new concrete floor slab of the primary construction section is shared as a road, and then the existing concrete floor of the secondary construction section The plate is removed, a concrete floor slab is installed in the removed secondary construction part, and the PC flooring material is inserted through the concrete floor slab and the end of the pretension precast PC plate installed in advance. The PC floor slab and the pre-tension precast PC plate are obtained by applying prestress to the concrete floor slab by tensioning the PC tension material. By adopting an integrated replacement PC floor slab, prestress similar to other parts can be introduced at the boundary between the primary replacement part and the secondary replacement part. And the overlapping part of the PC tendon material in the junction part of a primary construction part and a secondary construction part as shown in the prior art example decreases, and economical efficiency is high.

  Moreover, there is no need to leave a permanent temporary steel girder after completion of replacement, and the used temporary support material can be removed and reused, which is highly economical.

  Moreover, by replacing the primary construction part which is half using the pretension precast PC plate, the number of use of the tension fixing metal fittings of the PC tension material to be used can be reduced, and the cost can be reduced.

  According to the present invention, as described in claim 2, prior to the removal of the existing concrete floor slab of the primary construction section, a temporary support material is installed under the edge of the secondary construction section, so that the piece is cut by cutting the floor slab. The part that becomes the holding structure is reinforced, and the safety of the existing concrete slab of the secondary construction part can be secured.

  In the present invention, as described in claim 3, by installing a temporary support material under the edge on the secondary construction part side of the new pretension precast PC plate installed in the primary construction part, The part which becomes a cantilever structure before the replacement of the next construction part is reinforced, and can be shared as a road at an early stage.

  In the present invention, as described in claim 4, the temporary support member is a common construction steel that temporarily supports both the lower part of the existing concrete floor slab and the lower part of the pretension precast PC plate adjacent thereto. By using a girder, the temporary support material can be left as a structural material permanently, and the floor slab after replacement can be made high-strength.

  In the present invention, as described in claim 5, prestress is introduced into the entire width direction of the elevated concrete floor slab for the elevated road replacement PC floor slab after the replacement. It consists of a primary construction part and a secondary construction part that are divided into two parts, and the primary construction part supports a number of pretensioned precast PC plates prestressed by a pretensioning system in the length direction of the steel beam. A tension support section is provided on the back surface of the secondary construction part side end of the pretension precast PC plate, and the secondary construction part is configured with a post tension PC post tension PC plate, Pre-tensioned precast PC plate has a PC tension material inserted through the end surface of the post-tension PC plate and the tension bearing part. Are formed on the post-tension PC plate, and the PC tension material insertion hole is provided with a PC tension material insertion hole open to the end surface on the pretension precast PC plate side and the end surface on the opposite side. The pre-stress PC plate and the post-tension PC plate were integrated with each other by introducing the pre-stress PC plate pre-stress by tensioning the post-tension PC tension member inserted continuously in the post-tension PC plate. Thus, it is possible to avoid the complete closure of the road and to perform construction in a short time at a lower cost.

It is a cross-sectional view which shows an example of implementation of the replacement PC floor slab for elevated roads concerning this invention. It is a bottom view which shows the pretension precast PC plate used for the primary transfer part of the same PC floor slab. The construction process of an example of this invention method is shown, (a)-(c) is explanatory drawing of a first-half process. The construction process of an example of this invention method is shown, (d)-(f) is explanatory drawing of a latter half process. (A)-(c) It is stress explanatory drawing by the prestress of the replacement PC floor slab for elevated roads concerning this invention. The construction process of a conventional method is shown, (a)-(c) is explanatory drawing of a first-half process. The construction process of a conventional method is shown, (d)-(f) is explanatory drawing of a latter half process. It is stress explanatory drawing by the prestress of the replacement PC floor slab for elevated roads by the conventional method. It is sectional drawing which shows an example of the connection state of the primary construction part by a conventional method, and a secondary construction part. It is sectional drawing which shows the other example of the connection state of the primary construction part by a conventional method, and a secondary construction part. It is sectional drawing which shows the further another example of the connection state of the primary construction part by a conventional method, and a secondary construction part. It is sectional drawing which shows the further another example of the connection state of the primary construction part by a conventional method, and a secondary construction part.

  Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a replacement PC floor slab for an elevated road according to the present invention. This replacement PC floor slab 20 after replacement is divided into two parts of the existing concrete floor slab, and the primary construction part 20a, which is one section constructed in front of it, is constructed after the construction of the primary construction part 20a. It is comprised from the secondary construction part 20b which is other 1 division which was made, and the whole is supported by the some steel girder 21. As shown in FIG.

The primary construction part 20 a is configured by supporting a number of pretensioned precast PC plates 23 to which prestress is applied by the pretensioning system in the length direction of the steel beam 21.

  Although the pretension precast PC plate 23 is not shown in the drawing, the pretension PC tension member 24 is placed in a tensioned state with a desired tension in the mold and embedded in the mold so as to be embedded. After placing concrete and reaching a predetermined strength, the pretension PC tension member 24 is cut, and prestress is introduced into the precast concrete plate by the return force of the pretension PC tension member 24 at that time. is there.

  As shown in FIGS. 1 and 2, the pretension precast PC plate 23 is formed with a tension bearing part 25 protruding from the back surface, and communicates with the tension bearing part 25 from the end surface on the secondary construction part 20b side. An open PC tension material insertion hole 26 is formed, and a PC tension material end fixing tool 27 is embedded in the tension bearing section 25.

The secondary construction portion 20b is configured with a post tension PC floor slab 30 of the post tension system, and the post tension PC floor slab 30 communicates with the PC tension material insertion hole 26 of the adjacent pre tension precast PC plate 23. The PC tendon insertion holes 31 formed in the arrangement are opened through both ends toward the road width direction. A PC tendon end fixing tool 28 is embedded in the end surface of the PC tendon insertion hole 31 opposite to the pretension precast PC plate 23.

In addition, post-tensioned PC slab 30, precast reinforced concrete version of the bridged side-by-side (RC version), may be obtained by applying a pre-stress caused by post-tensioning for PC tendon 33, which will be described later after the erection, also cast-in-place The RC plate may be constructed on the steel beam 21 and prestressed by the post tension PC tension member 33.

The pre-tension precast PC plate 23 and the post-tension PC floor slab 30 are fixed to the above-mentioned PC tension material end portion by attaching the PC tension material 33 for post tension inserted through the respective PC tension material insertion holes 26 and 31 continuously. The members 27 and 28 are integrated with each other by being tensioned, and prestress is applied to the end portion of the pretension precast PC plate 23 and the entire area of the post tension PC floor plate 30.

  Next, an example of a method for replacing a concrete floor slab for an elevated road according to the present invention will be described.

In this method, one side of the two sections with the center in the road width direction of the existing concrete floor slab 40 shown in FIGS. 3 and 4 as a boundary is a primary construction part 20a, and the other side is a secondary construction part 20b. In the state where the part is shared as a road, the primary construction part 20a is replaced, and after the replacement of the primary construction part 20a is completed, the secondary construction part 20b is replaced and double-attached in a state where this is shared as a road The floor slabs of the replacement parts 20a and 20b are integrated to complete the replacement work.
Next, the replacement process of this example will be described in order.
a. Installation of temporary support material on the lower surface of the existing concrete floor slab cutting part

  As shown in FIG. 3 (a), in a state where the existing concrete slab 40 to be replaced is shared, this is divided into two, and the primary construction section 20a of one section to be constructed first, The temporary support material 41 is installed on the lower surface of the boundary part with the secondary construction part 20b of one section constructed after the replacement of the primary construction part 20a.

  This temporary support member 41 is in a state where a portion protruding from the steel girder 21 closest to the cut portion of the floor slab is supported in a cantilevered manner when the boundary between the preceding and succeeding rearrangement portions described later is cut. The lower surface of the tip of the cantilever is supported from the lower side to receive a downward load from the road surface.

  In this example, the temporary support member 41 is constituted by a diagonal member attached between the floor slab lower surface and the steel beam 21. As the temporary support material, in addition to the diagonal material, the temporary steel girder shown in the above-described conventional example may be used.

  b. Cutting of existing concrete floor slab, removal of primary construction section of existing concrete floor slab

  As shown in FIG.3 (b), the card rail 42 is installed in the edge upper surface of the secondary construction part 20b, and only the side of the secondary construction part 20b is shared as a road from this card rail 42, and the primary construction part 20a In the state where the upper passage is cut off, the boundary portion between the primary construction portion 20a and the secondary construction portion 20b of the existing concrete floor slab 40, in this example, the center portion in the road width direction of the existing concrete floor slab 40 is cut, and the existing concrete floor The primary construction part 20a of the plate 40 is removed.

This removal uses a crane as an example, lifts each section of the existing concrete slab 40 on the road traveling direction side by side, drops it to the ground, crushes it to the required size on the ground, and separates steel and concrete. Alternatively, it may be crushed in a state of being erected on the steel beam 21 to separate the concrete and the steel material.
c. Construction of pretension precast PC version in the primary construction department

As shown in FIG. 3 (c), a predetermined number of pretensioned precast PC plates 23 previously produced in a pre-concrete structure production yard on the steel beam 21 of the primary construction section 20a from which the existing concrete floor slab 40 has been removed. Are arranged side by side in the length direction of the steel girder 21 and the secondary construction portion 20b side edge portion of the new pretension precast PC plate 23 is supported by the temporary support material 41 to pretension precast the primary construction portion 20a. The PC plate 23 is made strong enough to withstand road use.
d. Removal of existing concrete slabs in the secondary construction department

The pre-tensioned precast PC plate 23 of the primary construction part 20a is made to have a sharable strength and the necessary surface is paved, and a temporary card on the edge of the secondary construction part 20b previously installed on the edge. The rail 42 is moved, the new pretension precast PC plate 23 of the primary construction part 20a is shared as a road, and the secondary construction part 20b is stopped.

  In this state, as shown in FIG. 3 (d), the existing concrete slab 40 of the secondary construction part 20b is removed. The removal of the existing concrete slab 40 is performed in the same manner as in the case of the primary construction portion 20a described above.

e. Construction of concrete floor slab in secondary construction department, introduction of prestress

  After removing the existing concrete floor slab 40 of the secondary construction part 20b, the concrete of the secondary construction part is constructed by laying a plurality of post-tension RC plates 43 side by side on the steel beam 21 as shown in FIG. 4 (e). Make up the slab. The RC plate 43 for post tension is installed by arranging precast RC plates formed in a predetermined shape in the production yard on the steel beam 21 in advance.

  Note that the concrete floor slab of the secondary construction section may be formed by cast-in-place concrete by assembling a formwork at the construction site without using the RC plate 43 for post tension.

After the RC plate 43 for post tension is temporarily installed, the PC tension material insertion hole 31 constituted by the sheath embedded in the RC plate 43 and the PC tension material insertion hole 26 of the pretension precast PC plate 23 communicated with the PC tension material insertion hole 26 are provided. The post-tension PC tension member 33 is inserted continuously, one end thereof is fixed to the PC tension member end fixing tool 27 on the back surface of the pretension precast PC plate 23, and the other end is fixed to the end surface of the post-tension RC plate 43. After passing through the PC tendon end fixing tool 28 and using a tensioning jack, the end is fixed to the PC tendon end fixing tool 28 to introduce prestress.

This pre-stress is introduced between the PC tension member end fixing devices 27 and 28 , and the post-tension PC floor slab 30 is configured by introducing pre-stress in the road width direction of the post-tension RC plate 43. .
f. Removal of temporary card rail and temporary support material, start of sharing of all widths

  After the new replacement PC floor slab 20 is constructed in this way, the temporary card rail 42 and the temporary support material 41 are removed as shown in FIG. 4 (f), and the entire width of the replacement PC floor slab 20 is moved to the road. Complete the replacement.

  The prestress of the connecting portion between the primary construction portion 20a and the secondary construction portion 20b in the replacement PC floor slab 20 configured as described above is the stress caused by the pretensioning PC tension member 24 of the pretension precast PC plate 23. As shown in the stress diagram shown in FIG. 5A, the stress gradually decreases at a certain length reaching the end and becomes 0 at the end, but the stress due to the post-tension PC tension member 33 is as shown in FIG. As shown in the stress diagram shown in b), a predetermined stress can be generated at the end of the precast PC plate 23, and these stresses are combined into the stress diagram shown in FIG. There is no portion where the stress is reduced in the connection portion between the construction portion 20a and the secondary construction portion 20b, and necessary stress is introduced over the entire width.

  In addition, when the primary construction part 20a is replaced, the use of the pretension type pretension precast PC plate 23 makes the PC tension material more expensive than the case of the post tension type precast PC plate or PC floor slab. The number of use of the PC tension member end fixing tool for fixing the toner can be reduced, and the cost can be reduced.

  In the above-described example, the temporary support member 41 is removed after completion of the replacement. However, when the temporary steel girder is used, the temporary support member 41 may be left as it is without being removed.

20 Replacement PC floor slab
20a Primary construction part 20b Secondary construction part 21 Steel girder 23 Pre-tension precast PC plate 24 Pre-tension PC tension member 25 Tension support part 26 PC tension member insertion hole 27 PC tension member end fixing tool
28 PC tension material end fixing tool
30 Post-tension PC slab 31 PC tension material insertion hole 33 Post-tension PC tension material 40 Existing concrete floor slab 41 Temporary support material 42 Temporary card rail 43 Post-tension RC plate

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