JP2018009371A - Deck slab replacement method for steel composite girder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a deck slab replacement method for the steel composite girder, which enables minimizing the dimensions of reinforcement members that are added for non-composition process during deck slab replacement of a steel composite girder and causes no drawback in crane installation works during deck slab removal.SOLUTION: A deck slab replacement method for the steel composite girder, which replaces an existing concrete deck slab CS of a steel composite girder that is a composition of a steel girder G1 and a concrete deck slab CS with a precast deck slab CS' in this invention comprises: a process of reinforcement member installation which installs to the steel girder G1 a reinforcement member L1 that is added meant for non-composition state before removing the existing concrete deck slab CS; a deck slab removal process which dismantles and removes the existing concrete deck slab CS; a fastener-relaxation process which loosens or temporarily removes all or part of joint members such as bolts tightening the reinforcement member L1 upon removing the deck slab; and a process of placing a precast deck slab CS' onto the steel girder G1 after re-tightening the aforesaid joint members that were loosened or removed once.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a steel composite girder floor slab replacement method, and more particularly to a steel composite girder floor slab replacement method in which a steel composite girder floor slab is replaced with a precast PC floor slab.

  Conventionally, in such a steel composite girder floor slab replacement method, a steel composite girder floor slab is replaced with a precast PC floor slab or the like. For example, in Patent Document 1, when replacing a composite slab floor slab with a precast floor slab, remove the existing composite girder floor slab and synthesize the precast floor slab before synthesizing the precast floor slab. The main girder is placed with the box opening formed on the precast floor slab positioned on the upper flange of the main girder in order to prevent the main girder from falling down and to eliminate the disadvantages of existing prevention measures. Set the distance between the boxed parts in the direction to the distance between the fixed points, temporarily fix the precast floor slab and main girder at the boxed part, and release the fixation after the precast floor slab is installed and place concrete in the boxed part The main girder lateral buckling prevention construction method is disclosed (see claim 1 of Patent Document 1, paragraphs [0008] to [0010] of the specification, FIG. 1 of FIG. 1, FIG. 9 and the like).

  However, when the steel composite girder floor slab is replaced with the precast PC floor slab in the steel composite girder floor slab replacement method, as in the main girder lateral buckling prevention method described in Patent Document 1, the steel girder And a precast PC floor slab need to be integrated and synthesized, so a large number of stud gibels (hereinafter simply referred to as studs) connecting the steel girder and the PC floor slab are required. For this reason, as a result, the hole of the PC floor slab for the stud increases, and as shown in FIG. 10, there is a problem that it is difficult to arrange the PC steel material to which prestress is applied.

  Therefore, by adding a reinforcing member (steel member) to the steel girder, the steel girder and the PC slab are not synthesized to reduce the number of studs and solve the above problem. However, if non-synthesizing is performed before the floor slab is removed, the steel girder will be returned to the reinforcing member added to the steel girder for non-synthesizing. Stress acts on the girders (see FIG. 6). This stress is inherently advantageous when the replacement work is completed, but if a reinforcing member is added before the floor slab is removed, this stress acts on the additional reinforcing member and is not only obstructed, but the stress is also reduced. However, there is a problem that the size of the reinforcing member becomes larger than necessary in order to be able to compete.

JP-A-8-218327

  Therefore, the present invention has been devised in view of the above-mentioned problems, and the object of the present invention is to measure the size of a reinforcing member to be added for non-synthesis when replacing a steel slab floor slab. It is an object of the present invention to provide a method of replacing a steel slab floor slab that can be made as small as possible and that does not interfere with the lifting work when the slab is removed.

  The steel composite girder floor slab replacement method according to the first aspect of the present invention is a steel composite girder floor slab replacement in which an existing concrete floor slab of a steel composite girder integrated with a steel girder and a concrete floor slab is replaced with a precast floor slab. Before removing the existing concrete slab, it is a construction method, a reinforcing member attaching step for attaching a reinforcing member to be added and reinforced for non-synthesis to the steel girder, and dismantling and removing the existing concrete slab A floor slab removing step, and after the floor slab removing step, all or a part of a joining member such as a bolt for tightening the reinforcing member is loosened or once loosened, and once loosened or removed. After the joint member is tightened again, the precast slab is placed on the steel beam.

  In the floor slab replacement method according to the second invention, in the first invention, in the floor slab removal step, a lifting machine such as a crane is placed on the steel girder to which the reinforcing member is attached in the reinforcing member attaching step. And removing the existing concrete slab.

  The floor slab replacement method according to a third aspect of the present invention is characterized in that, in the first aspect or the second aspect, the precast floor slab is a pre-tensioned precast PC floor slab pre-stressed.

  According to the first to third inventions, since there is a tightening relaxation process in which all or a part of the joining member for tightening the reinforcing member is loosened or temporarily removed, the non-synthetic process is performed when the steel composite girder is replaced. Therefore, the size of the reinforcing member to be added for the purpose of reduction can be reduced as much as possible, and the replacement cost of the floor slab can be reduced. Moreover, since the reinforcement member attachment process which attaches a reinforcement member to a steel girder is performed before removing an existing concrete floor slab, there is no problem also in the lifting work at the time of removal of a floor slab.

  In particular, according to the second invention, it is possible to perform a floor slab removal step by installing a lifting machine on a steel beam to which a reinforcing member is attached. For this reason, it is possible to safely remove the slab in a short time and to reduce the size of the lifting machine used for the slab removal work, thereby reducing the cost of the slab removal work. it can. In addition, the floor slab can be removed even in an environment where a lifting machine cannot be installed under the bridge.

  In particular, according to the third invention, the new floor slab to be replaced can be made large, the replacement work of the floor slab can be performed in a short time, and the cost of the floor slab removal work can be reduced. Can do.

It is a flowchart which shows each process of the floor slab replacement construction method which concerns on embodiment of this invention. It is a vertical sectional view which shows the existing steel composite girder before performing replacement work by the same floor slab replacement method. It is process explanatory drawing which shows the reinforcement member attachment process of a floor slab replacement construction method same as the above. It is a vertical sectional view showing another embodiment of a reinforcing member. It is process explanatory drawing which shows the floor slab removal process of a floor slab replacement construction method same as the above. It is stress explanatory drawing which represented typically the stress which generate | occur | produces in a steel girder when an existing concrete floor slab is removed by the floor slab removal process same as the above. It is a figure which compares and shows the difference in the dimension of the reinforcement member at the time of reinforcing before and after floor slab removal same as the above. It is process explanatory drawing which shows the PC floor slab installation process of a floor slab replacement construction method same as the above. It is stress explanatory drawing which represented typically the stress which generate | occur | produces in a steel girder when installing a newly installed PC floor slab by the PC floor slab installation process same as the above. It is a top view which shows the problem of the conventional PC floor slab.

  Hereinafter, an embodiment for carrying out a floor slab replacement method according to the present invention will be described in detail with reference to the drawings.

  The floor slab replacement method according to the embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a flowchart showing each step of a floor slab replacement method according to an embodiment of the present invention. As shown in FIG. 1, the floor slab replacement method according to the present embodiment is an existing steel composite girder in which a steel girder and a concrete floor slab are integrated by performing the steps (1) to (6). This method replaces the concrete slab with a precast slab. Next, each process of the floor slab replacement method according to the embodiment will be described.

  First, an existing steel composite girder before replacement work will be briefly described. FIG. 2 is a vertical cross-sectional view showing a state in which an existing steel composite girder before being replaced by the floor slab replacement method according to the present embodiment is cut along a vertical cross section perpendicular to the bridge axis direction. The steel composite girder 1 shown in the figure is a stud (stud gibber) SJ mainly composed of a steel girder G1 which is a main girder and an existing concrete floor slab CS made of reinforced concrete, and is implanted on the upper surface of the steel girder G1. A steel composite girder in which a steel girder G1 and a concrete floor slab CS are integrated.

  This steel girder G1 is an I-shaped cross-section steel plate assembled by welding thick steel plates having predetermined dimensions, and includes an upper flange G10, a lower flange G11, and a web G12 connecting these. Since this upper flange G10 is calculated as an integral part of the existing concrete floor slab CS, it is generally smaller in width than the lower flange G11.

  Further, when the steel girder G1 and the existing concrete floor slab CS are not synthesized, the steel girder G1 is bent even if the upper flange G10 is calculated as a separate body from the existing concrete floor slab CS. Must be less than or equal to a predetermined value. For this reason, the below-mentioned reinforcement member L1 added and reinforced as a stiffener which raises rigidity is attached to the upper part of the steel beam G1.

(1) Reinforcing member attaching step FIG. 3 is a process explanatory view showing the (1) reinforcing member attaching step of the floor slab replacement method according to this embodiment, and shows a vertical section similar to FIG. As shown in FIG. 3, in the floor slab replacement method according to the present embodiment, first, a reinforcing member attaching step for attaching the reinforcing members L1 and L1 to be added and reinforced for non-synthesis to the steel beam G1 is performed.

  Specifically, a bolt hole (for example, a diameter of 24 mm) for inserting a bolt is drilled in the upper part of the web G12 of the existing steel girder G1. Thereafter, the reinforcing member L1 is applied to the mounting position of the upper portion of the web G12, and a high-strength bolt (not shown) which is a joining member (for example, torcia) in a state where the lower surface of the upper flange G10 and the upper surface of the reinforcing member L1 are separated by a predetermined distance The reinforcing member L1 is bolted (friction bonded) to the web G12 with a high-strength bolt TCB M22 (S10T).

  The reason why the lower surface of the upper flange G10 and the upper surface of the reinforcing member L1 are separated from each other by a predetermined distance is to apply rust prevention coating or the like. For this reason, when it is not necessary to keep a space | interval on rust prevention processing, such as creating a reinforcement member from a corrosion-resistant steel plate, even if it installs by making the lower surface of upper flange G10 and the upper surface of the reinforcement member L1 contact, No problem.

  In addition, the dimensions and the like of the reinforcing member L1 to be reinforced are calculated and determined by structural calculation. In the illustrated embodiment, two L-250 × 250 × 25 equilateral angle steels are provided on the left and right sides of the web G12. The case where it attaches is illustrated.

  Depending on the result of the structural calculation, in addition to the reinforcing members L1 provided on the left and right sides of the upper portion of the web G12, the reinforcing members may be provided on both sides of the lower portion of the web G12 of the steel girder G1 as shown in FIG. L2 may be provided.

(2) Floor slab removal process Next, in the floor slab replacement method according to this embodiment, a floor slab removal process for dismantling and removing an existing concrete floor slab is performed. FIG. 5 is a process explanatory view showing the (2) floor slab removal process of the floor slab replacement method according to the present embodiment, and shows a vertical section similar to FIG.

  Specifically, the steel girder G1 and the existing concrete floor slab CS are removed by scraping the concrete around the stud SJ with a drilling machine such as a call pick hammer or a hydraulic breaker, or by cutting the stud SJ from the root. And disconnect. Then, the existing concrete floor slab CS is cut / divided into a size capable of being lifted using a diamond cutter, a punching machine, or the like, and removed.

  At this time, in the floor slab replacement method according to the present embodiment, the reinforcing member attaching step is executed before this step, and the steel girder G1 separated from the existing concrete floor slab CS has already been reinforced. The existing concrete slab CS can be lifted and removed by a lifting device capable of self-propelling on the existing concrete slab CS. For this reason, the lifting work at the time of removal of the existing concrete slab CS is easy and can be performed in a short time.

  On the other hand, when the existing concrete floor slab CS is removed without reinforcing the steel girder G1, when a heavy machine such as a crane runs on the existing concrete floor slab CS, the steel is separated from the floor slab and made unsynthetic. There is a problem that the bending of the girder G1 becomes too dangerous. Moreover, it is not only dangerous, but it is necessary to manage the bending of the steel girder G1, such as by installing a support under the steel girder G1, and it takes time to dismantle and remove the floor slab. This also raises the problem of increased costs.

  FIG. 6 is a stress explanatory diagram showing the stress generated when the existing concrete floor slab CS is removed by this process in the vertical cross section along the bridge axis direction of the steel girder G1. As shown in FIG. 6, when the existing concrete slab CS is removed by this process, the steel girder G1 bent downward by the load of the existing concrete slab CS tends to return to the original state. At this time, a tensile force acts on the upper flange G10 of the steel girder G1, and a compressive force acts on the lower flange G11.

  In the floor slab replacement method according to this embodiment, the above-described reinforcing member attaching step is performed before the floor slab removing step. For this reason, the stress shown in FIG. 6 also acts on the reinforcing member L1. These stresses are inherently advantageous in supporting the floor slab when it is replaced with a new floor slab. However, when the reinforcing member attaching step is performed before the floor slab removing step, this advantageous stress is not only hindered by the reinforcing member L1, but the reinforcing member L1 must be designed to resist this stress. Don't be.

  Therefore, the reinforcing member L1 to be attached before the floor slab removing process has a problem that it must have a size considerably larger than the design when the reinforcing member is attached after the floor slab removing process. FIG. 7 is a diagram showing a comparison of the difference in dimensions of the reinforcing members when the reinforcement is performed before and after the floor slab removal. Of course, the reinforcing member is appropriately determined depending on the size and conditions of the bridge, and cannot simply be compared. However, as an example, as shown in FIG. 7 a), when reinforcement is performed before the floor slab removal step, the reinforcing member needs to be a 500 × 50 assembled steel plate, In the case of reinforcement, there is a calculation result that, as shown in b), an L-250 × 250 × 25 equilateral mountain steel is sufficient.

  Thus, in order to perform a lifting device such as a crane, it is preferable to reinforce before the floor slab removal process, but the required size of the reinforcing member varies greatly depending on whether to reinforce before the floor slab removal process. There was a contradiction problem. However, the inventors of the present application solved this problem by performing the following tightening relaxation process.

(3) Tightening relaxation process Next, as shown in FIG. 1, in the floor slab replacement method according to the present embodiment, all or part of the joining member that tightens the reinforcing member L1 is loosened or temporarily removed. Perform the process. Specifically, all or a part of the joining members that fasten the reinforcing member L1 to the steel girder G1 in a state where the existing concrete floor slab CS is all removed and no load other than its own weight is applied to the steel girder G1. loosen.

  As described above, in the floor slab replacement method according to the present embodiment, the torcia-type high-strength bolt is used as the joining member, so that the loosened bolt cannot be reused and discarded, but in this step Then, the reinforcing member L1 is loosened so as not to be detached, or the reinforcing member L1 is temporarily removed. In addition, the range of the joining member to be loosened or removed may be appropriately determined according to the situation such as the range of floor slab removal and the length of the reinforcing member L1 or the steel beam G1.

  By performing this process, the bending of the steel girder G1 due to the load of the existing concrete floor slab CS is eliminated without hindering the action of the stress shown in FIG. 6 with the reinforcing member L1, and the steel girder G1 is loaded by loading the new floor slab. It works favorably during the stress distribution that occurs (see FIG. 9).

(4) Re-clamping step Next, as shown in FIG. 1, in the floor slab replacement method according to the present embodiment, a re-clamping step of re-tightening the joint member loosened in the previous step is performed. Of course, when the reinforcing member L1 is removed, or when it is not possible to retighten using the Torcia type high strength bolt as the joining member, the reinforcing member L1 is bolted to the web G12 with a new joining member. In short, the retightening means that the tightening force necessary to generate the predetermined frictional joining force necessary for bolting the reinforcing member L1 to the web G12 is generated again.

(5) PC floor slab installation process Next, as shown in FIG. 8 and FIG. 1, in the floor slab replacement method according to the present embodiment, a newly installed concrete floor slab CS ′ is placed on a steel girder G1 and predetermined. PC floor slab installation process to be installed at the position. FIG. 8 is a process explanatory view showing a PC floor slab installation process of the floor slab replacement method according to the present embodiment, and is shown by a vertical cross section similar to FIG. Specifically, a new concrete floor slab CS ′ is installed over a predetermined position of the steel beam G1 using a lifting device such as a rough terrain crane.

  The concrete floor slab CS 'installed in this step is a pre-tensioned precast PC floor slab pre-stressed. Therefore, the concrete floor slab CS 'can be a large-sized precast floor slab having a large span in the longitudinal direction along the PC steel material due to the action of prestress. For this reason, the working time of this process can be shortened by reducing the number of times the concrete floor slab CS 'placed in this process is lifted and suspended.

  Of course, the concrete floor slab to be newly installed may be a precast PC floor slab that uses pre-tension and post-tension, or a post-tension precast PC floor slab. In short, the concrete floor slab to be newly installed may be a precast PC floor slab that has been previously placed in a factory or the like and prestressed.

  However, the presence or absence of prestress is not essential, and it is possible to replace the newly installed concrete floor slab with a precast concrete PCa floor slab.

(6) Filler Filling Step Next, as shown in FIG. 1, in the floor slab replacement method according to this embodiment, a new cotter (not shown), which is a hole for a stud of the concrete floor slab CS ′, is newly added. A stud filling step is performed in which a stud SJ ′ is melt-planted and a filler such as concrete or non-shrink mortar is filled therearound.

  However, since the steel girder G1 and the concrete floor slab CS 'are non-synthetic designs, the number of cotters and studs is extremely small compared to the existing concrete floor slab CS.

  Thereafter, as shown in FIG. 1, a curing period until the filler is hardened is taken, and other necessary operations such as asphalt pavement are performed on the concrete floor slab CS ′ to perform the floor slab according to the present embodiment. The slab replacement work for the replacement method is completed.

  According to the floor slab replacement method according to the present embodiment described above, since the whole or part of the joining member for fastening the reinforcing member L1 is loosened or temporarily removed, the size of the reinforcing member L1 is reduced as much as possible. The manufacturing cost of the reinforcing member L1 can be reduced, and the replacement cost of the floor slab can be reduced.

  Moreover, according to the floor slab replacement method according to the present embodiment, the reinforcing member L1 is attached to the steel girder G1 before the existing concrete floor slab CS is removed, which hinders lifting work when the floor slab is removed. There is no. That is, according to the floor slab replacement method according to the present embodiment, the existing concrete floor slab CS can be removed with a lifting device such as a rough terrain crane that can self-propell on the existing concrete floor slab CS. For this reason, the lifting work at the time of removal of the existing concrete floor slab CS can be performed safely and easily in a short time, and in this respect also, the cost of replacing the floor slab can be reduced.

  Moreover, according to the floor slab replacement method according to the present embodiment, it is possible to approach the nearest distance of the floor slab to be removed by running on the existing concrete floor slab CS to be removed. The size can be reduced, and the cost for removing the slab can be reduced. In addition, the floor slab can be removed even in an environment where a lifting machine cannot be installed under the bridge.

  In addition, according to the floor slab replacement method according to this embodiment, by using a pre-tension type precast PC floor slab, the new floor slab to be replaced can be made large, and the floor slab replacement work Can be performed in a short time. Thereby, the cost reduction of the floor slab removal work can be further achieved.

  As mentioned above, although the floor slab replacement method according to the present embodiment has been described in detail, the above-described or illustrated embodiment is merely an embodiment embodied in carrying out the present invention, Therefore, the technical scope of the present invention should not be construed in a limited manner.

G1: Steel girders (main girders)
G10: Upper flange G11: Lower flange G12: Web CS: Existing concrete floor slab CS ': New concrete floor slab SJ, SJ': Stud L1, L2: Reinforcing member

Deck replacement method of steel synthetic girder according to the first invention, the steel synthetic replacing steel girder and concentrated rie preparative slab and has an existing Conc rie preparative slab of steel synthesis digits together in precast slab A slab replacement method for a girder, wherein before the existing concrete slab is removed, a reinforcing member attaching step for attaching a reinforcing member to be added to the steel girder for non-synthesis, and the existing concrete A floor slab removal step of dismantling and removing the floor slab, and a binding relaxation step of loosening or temporarily removing all or part of the joining member that tightens the reinforcing member after the floor slab removal step. Or after fastening the removed said joining member again, the said precast floor slab is mounted in the said steel beam.

The floor slab replacement method according to the embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a flowchart showing each step of a floor slab replacement method according to an embodiment of the present invention. As shown in FIG. 1, the floor plate replacement method according to the present embodiment, (1) performing the steps of - (6), steel synthesis and steel girder and concentrated rie preparative slab are integrated the existing Conch rie door floor version of the digit is a method to replace the precast slab. Next, each process of the floor slab replacement method according to the embodiment will be described.

First, an existing steel composite girder before replacement work will be briefly described. FIG. 2 is a vertical cross-sectional view showing a state in which an existing steel composite girder before being replaced by the floor slab replacement method according to the present embodiment is cut along a vertical cross section perpendicular to the bridge axis direction. The steel composite girder 1 shown in the figure is a stud (stud gibber) SJ mainly composed of a steel girder G1 which is a main girder and an existing concrete floor slab CS made of reinforced concrete, and is implanted on the upper surface of the steel girder G1. and a steel girder G1 and the Conch rie door deck CS is a steel synthetic digits together.

Claims (3)

A steel composite girder slab replacement method that replaces an existing concrete slab of a steel composite girder in which a steel girder and a concrete floor slab are integrated with a precast floor slab,
Before removing the existing concrete floor slab, a reinforcing member attaching step for attaching a reinforcing member to be added and reinforced for non-synthesis to the steel girder,
A floor slab removal step of dismantling and removing the existing concrete floor slab;
After the floor slab removal step, all or part of a joining member such as a bolt that tightens the reinforcing member is loosened or a binding relaxation step of temporarily removing the bonding member,
A steel composite girder slab replacement method, wherein the joint member once loosened or removed is tightened again, and then the precast slab is placed on the steel girder. 2. The floor slab removal step includes placing a lifting machine such as a crane on the steel girder to which the reinforcement member is attached in the reinforcement member attachment step, and removing the existing concrete floor slab. The steel composite girder floor slab replacement method described in 1. The method of replacing a steel composite girder slab according to claim 1 or 2, wherein the precast slab is a pre-tensioned precast PC slab pre-stressed.