Methods for cutting deck slabs, deck slab replacement methods, and shear reinforcement structures

Abstract

To further reduce a construction traffic regulation time to be accompanied in floor slab renewal construction by detaching an existing floor slab and a main girder while opening traffic.SOLUTION: A cutting method of a floor slab for cutting and detaching a concrete floor slab and a main girder of a bridge at their junction comprises: a reinforcement step of providing a shear reinforcement structure adjacent to a cutting section located at the junction in a bridge axial direction; and a cutting surface formation step of forming a cutting surface approximately parallel to the main girder at the cutting section.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a method for cutting a floor slab that cuts and separates the joint between a concrete floor slab and a main girder, a floor slab replacement method using the floor slab cutting method, and a shear reinforcement structure for the joint used in the floor slab cutting method.

Background Art

[0002] The work of renewing the floor slab of a bridge is an operation of replacing a deteriorated existing floor slab with a new floor slab having high durability. During this operation, traffic must be blocked. Therefore, although it involves construction traffic regulations such as stopping the passage of general vehicles and various traffic restrictions, it is necessary to minimize the time of the construction traffic regulations so as to have as little impact on the existing traffic as possible.

[0003] However, in the work of replacing with a new floor slab, the existing floor slab must be removed from the existing girder, and the removal work requires a great deal of working time. In particular, the removal of the concrete around the displacement prevention of the composite girder, which was rationalized by integrating the behavior of the floor slab and the steel girder, took more time than the non-composite structure.

[0004] Therefore, in order to minimize the construction traffic regulation time, the inventors proposed a method (Patent Document 1) in which all cutting devices are arranged under the floor slab so that the cutting of the existing floor slab for removal can be started simultaneously with the start of the construction traffic regulation, and a method (Patent Document 2) in which the cut floor slab can be recombined with the original steel girder to open the traffic, and filed a patent application.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] According to Patent Documents 1 and 2, it is possible to carry out bridge deck replacement work while shortening the period of traffic restrictions during construction. However, when bridge deck replacement work is carried out in areas such as urban areas with heavy traffic or mountainous areas sandwiched between long tunnels, the impact on the traffic environment of the surrounding area is enormous. For this reason, there is a strong desire to realize bridge deck replacement work that takes into account the period of traffic restrictions during construction even more.

[0007] This invention has been made in view of the above problems, and its main purpose is to further shorten the time of traffic restrictions during deck replacement work by cutting and separating the concrete deck slab and the main girder while keeping general vehicle traffic open. [Means for solving the problem]

[0008] To achieve this objective, the present invention provides a method for cutting a bridge deck, which involves cutting and separating the concrete deck and main girder of a bridge at a joint, and is characterized by comprising: a reinforcement step of providing a shear reinforcement structure adjacent to the cutting section set at the joint and in the bridge axis direction; and a cutting surface forming step of forming a cutting surface substantially parallel to the main girder in the cutting section.

[0009] According to the present invention's method for cutting a bridge deck, by installing a shear reinforcement structure at the joint adjacent to the cutting section, it is possible to provide reinforcement that is sufficient to compensate for the insufficient shear force in the substantially horizontal direction when performing the cutting surface formation process in the cutting section. As a result, the cutting surface formation process can be carried out while general vehicles are allowed to pass without restricting the load or restricting the traffic lane, thereby shortening the time of traffic restrictions associated with bridge deck replacement work and minimizing the impact on existing traffic.

[0010] The present invention provides a method for cutting a floor slab, comprising a planning step of setting a work area at the joint and dividing the work area into multiple cutting sections; formulating a work procedure for the cutting section, which includes a cutting surface formation step and a replacement step for replacing the cut and separated concrete floor slab, as a replacement work plan for the work area; and conducting a safety analysis that reflects the replacement work plan.

[0011] According to the present invention's method for cutting a deck slab, a safety analysis is performed during construction. This allows for verification of the necessity of safety measures during construction based on highly reliable analysis results that reflect the replacement work plan, regardless of the order in which work is initiated on multiple cutting sections within the construction area. Therefore, if it is determined that safety measures are unnecessary, the reinforcement process can be omitted, making it possible to perform the cut surface formation process safely and efficiently.

[0012] The present invention relates to a deck slab replacement method for replacing a concrete deck slab installed on the main girder of a bridge, and is characterized by comprising: a cutting step of cutting and separating the concrete deck slab and the main girder at the joint using the deck slab cutting method of the present invention; and a replacement step of removing the concrete deck slab and replacing it with a new deck slab. Furthermore, the cutting step and the replacement step are carried out based on the replacement work plan.

[0013] According to the deck slab replacement method of the present invention, since it is possible to ensure a period of general vehicle traffic opening during the cutting process, the only process in the deck slab replacement method that requires construction traffic restrictions is the concrete deck slab replacement process. This increases the flexibility of the work process and improves constructability.

[0014] The floor slab replacement method of the present invention comprises a recombination step in which the concrete floor slab and the main girder, which were cut and separated in the cutting step, are recombined using a detachable composite jig, and is characterized in that the composite jig is removed together with the concrete floor slab in the replacement step.

[0015] According to the deck replacement method of the present invention, since the cut and separated concrete deck and main girders are reassembled using a composite jig, general vehicle traffic can remain open even after the cutting process is completed. This makes it possible to adjust the timing of the commencement of the concrete deck replacement process to match the time when construction traffic restrictions can be implemented, thereby improving the overall work efficiency of the deck replacement project.

[0016] The shear reinforcement structure of the present invention is a shear reinforcement structure used in the method of cutting a floor slab of the present invention, characterized in that it comprises a reinforcing member installed at a position adjacent to the cutting section, spanning the concrete floor slab and the main girder.

[0017] The shear reinforcement structure of the present invention is characterized in that the reinforcing member is a sheet material fixed to the side surface of the joint.

[0018] The shear reinforcement structure of the present invention is characterized in that the reinforcing member is a bolt material enclosed within the joint.

[0019] The shear reinforcement structure of the present invention is characterized by comprising a composite jig installed on the side surface of the joint, which is capable of recombining the cut and separated concrete floor slab and the main girder.

[0020] The shear reinforcement structure of the present invention is characterized in that the reinforcing member comprises a steel plate for mechanical joining installed on the main girder and a bolt material that penetrates the steel plate for mechanical joining and is contained within the joint.

[0021] The shear reinforcement structure of the present invention is characterized in that the reinforcing member comprises a steel plate for adhesion that is attached to the side surface of the joint.

[0022] According to the shear reinforcement structure of the present invention, with a simple structure in which a reinforcing member is installed across the concrete floor slab and the main girder at a position adjacent to the cutting section, by performing the cutting surface forming process in the cutting section, reinforcement corresponding to the insufficient substantially horizontal shear force can be achieved. Further, if general materials such as sheet materials and bolt materials are adopted for the reinforcing member, it becomes possible to omit the labor of separately manufacturing dedicated members.

[0023] Furthermore, if a synthetic jig is adopted for the reinforcing member, the used synthetic jig can be reused in the recombining process of recombining the cut-off concrete floor slab and the main girder after the cutting process of the connection part is completed. Thereby, the number of members used in the floor slab replacement method can be reduced, and it becomes possible to contribute to cost reduction of the construction cost.

Effect of the Invention

[0024] According to the present invention, by providing a shear reinforcement structure at the joint between the concrete floor slab and the main girder, the concrete floor slab and the main girder can be cut and separated while opening the traffic of general vehicles, so that it is possible to further shorten the construction traffic regulation time associated with the floor slab renewal work and minimize the impact on the existing traffic.

Brief Description of the Drawings

[0025] [Figure 1] It is a diagram showing the procedure of a floor slab replacement method including a floor slab cutting method in an embodiment of the present invention (in the direction orthogonal to the bridge axis). [Figure 2] It is a diagram showing the procedure of a floor slab replacement method including a floor slab cutting method in an embodiment of the present invention (in the bridge axis direction). [Figure 3] It is a diagram showing the flow of a floor slab replacement method including a floor slab cutting method in an embodiment of the present invention. [Figure 4] It is a diagram showing a shear reinforcement structure in an embodiment of the present invention. [Figure 5] It is a diagram showing another example of a shear reinforcement structure in an embodiment of the present invention. [Figure 6]This figure shows the construction steps to be carried out in the floor slab replacement method according to an embodiment of the present invention (example of Case 1). [Figure 7] This figure shows the construction steps to be carried out in the floor slab replacement method according to an embodiment of the present invention (another example of Case 1). [Figure 8] This figure shows the construction steps to be carried out in the floor slab replacement method according to an embodiment of the present invention (example of Case 2-1). [Figure 9] This figure shows the construction steps to be carried out in the floor slab replacement method according to an embodiment of the present invention (Case 2-2 example). [Figure 10] This figure shows the construction steps to be carried out in the floor slab replacement method according to an embodiment of the present invention (example of Case 3). [Figure 11] This is a diagram illustrating a schematic replacement work plan in an embodiment of the present invention. [Figure 12] This figure shows another example of a shear reinforcement structure in an embodiment of the present invention (a post-installed anchor using steel plates for mechanical joining). [Figure 13] This figure shows another example of the shear reinforcement structure (adhesive steel plate) in an embodiment of the present invention. [Modes for carrying out the invention]

[0026] This invention aims to shorten the time of traffic restrictions during bridge deck replacement work by performing the cutting and separating of the concrete deck and main girders, which is one of the work processes in bridge deck replacement work, while keeping the bridge open to traffic.

[0027] The following describes in detail the deck cutting method, deck replacement method, and shear reinforcement structure of the present invention, using a composite I-girder bridge, a simple girder type in which main girders are independently placed in multiple spans and which has three main girders made of I-beams, with reference to Figures 1 to 11.

[0028] As shown in Figure 1(a), the bridge 200 has steel main girders 201 and concrete deck slabs 202 installed on the main girders 201, with haunch sections 204 formed on the underside of the concrete deck slabs 202 to serve as joints with the main girders 201. In addition, multiple bracing girders 203 and transverse girders 205 are provided between adjacent main girders 201 in the direction perpendicular to the bridge axis, spaced apart in the direction of the bridge axis, as shown in Figure 2(a).

[0029] In a bridge 200 with a composite structure in which the concrete deck slab 202 and steel main girders 201 are integrated, the general procedure for deck slab replacement work using the deck slab replacement method is as follows:

[0030] <> As shown in the flowchart in Figure 3, the deck slab replacement method comprises a cutting process, a reassembly process, and a replacement process, with the cutting process employing a deck slab cutting method.

[0031] ≪≪Cutting process≫≫ ≪Method for cutting the deck slab: Planned process≫ First, a construction area A for replacing the concrete deck slab 202 is set, and this construction area A is divided into sections to set multiple cutting sections B. In this embodiment, as shown in Figures 1(a) and 2(a), the construction area A is set to the leftmost part of the three divisions in the direction perpendicular to the bridge axis, and a part of the section between the support points 207 is set in the direction of the bridge axis.

[0032] Furthermore, the construction area A was divided along the bridge axis direction at the positions of the bracing 203 and the transverse girder 205, and four cutting sections B were established. After this, a replacement work plan, as described later, was formulated and a safety analysis was conducted. In this embodiment, an example is given of a case where the four cutting sections B are set as one replacement group, and a replacement work plan is formulated in which the replacement process is carried out simultaneously within this group.

[0033] ≪Method for cutting floor slabs: Reinforcement process and cut surface formation process≫ The necessity of safety measures for the arbitrarily selected cutting section B will be verified, and if deemed necessary, a reinforcement area D will be set in the haunch section 204 adjacent to cutting section B, as shown in Figure 4(a). The work of installing the shear reinforcement structure 300 in reinforcement area D will be carried out while general vehicle traffic remains open.

[0034] Subsequently, as shown in Figure 2(b), a cut surface 204a parallel to the main girder 201 is formed along the upper surface of the main girder 201 in the haunch section 204 of the selected cutting section B, thereby cutting and separating the concrete slab 202 and the main girder 201. If it is determined that safety measures are unnecessary, the step of installing the shear reinforcement structure 300 is omitted, and the cut surface 204a is formed in the haunch section 204.

[0035] ≪≪Resynthesis process≫≫ Next, while keeping the road open, the composite structure 100 is formed in the cut section B after the cut surface formation process is carried out, as shown in Figures 1(c) and 2(c). The composite structure 100 formed in the haunch section 204 of the cut section B recombines the concrete deck slab 202 and the main girder 201, allowing general vehicle traffic to remain open.

[0036] Subsequently, while maintaining the road open to traffic, the reinforcement process, cut surface formation process, and resynthesis process are sequentially carried out for each of the four cut sections B shown in Figure 2(a) according to the procedure described above. As a result, the replacement group consisting of the four cut sections B becomes ready for the replacement process.

[0037] <<<Replacement Process>>> Therefore, traffic restrictions are put in place to limit the passage of general vehicles, and the composite structure 100 and the cut and separated concrete deck slab 202 are removed as shown in Figure 1(d). A new deck slab is installed on the main girder 201 after removal, but as shown in Figure 2(d), if the new deck slab 206 is to be installed as the new deck slab, the necessary surface preparation is carried out on the upper surface of the main girder 201 after the concrete deck slab 202 has been removed. Note that the new deck slab may be, for example, a temporary deck slab.

[0038] As described above, when a recombination process is carried out in the deck slab replacement method, the concrete deck slab 202 and main girder 201 can be cut and separated sequentially for each of the four cut sections B set in the construction area A, and then the replacement process of the concrete deck slab 202, which requires construction traffic restrictions, can be carried out simultaneously for all four cut sections B, thereby improving the overall work efficiency of the deck slab replacement work.

[0039] Furthermore, if there are restrictions on the time periods during which construction traffic restrictions can be implemented, as shown in Figure 2(c), it is possible to continue allowing general vehicle traffic to remain open with the composite structure 100 in place and adjust the timing of commencing the concrete deck slab 202 replacement process.

[0040] Incidentally, the process of forming a cut surface 204a in the haunch portion 204 involves cutting the headed stud 2011, as shown in Figures 1(b) and 2(b). The headed stud 2011 is provided on the upper flange of the main girder 201 and embedded in the haunch portion 204, and functions as a shearing restraint for the concrete deck slab 202 in the substantially horizontal direction (mainly in the bridge axis direction). Other shearing restraints include horseshoe-shaped dowels (not shown), and this method can also be applied to them.

[0041] Cutting such headed studs 2011 would result in insufficient shear force, potentially causing a nearly horizontal displacement between the concrete deck slab 202 and the main girder 201 during general vehicle traffic, thus compromising safety. For this reason, prior to the cut surface formation process, a reinforcement process is carried out to install a shear reinforcement structure 300, as shown in Figure 2(b). The compressive force from the concrete deck slab 202 to the main girder 201 is borne by the bearing pressure between the lower surface of the concrete deck slab 202 and the upper surface of the main girder 201, as they are in contact.

[0042] Shear reinforcement structure As shown in Figure 4(a), the shear reinforcement structure 300 is installed in a reinforcement area D adjacent to the cutting section B before the cutting and separation process is carried out, and as shown in Figures 4(b) and 4(c), it comprises at least a reinforcing member 301. The reinforcing member 301 is positioned to straddle the concrete slab 202 and the main girder 201 with respect to the haunch section 204.

[0043] Any material can be used as the reinforcing member 301, as long as it can provide sufficient reinforcement to compensate for the substantially horizontal shear force that is lost when the headed stud 2011 located at cutting section B is cut. Generally, in composite girders, the shear force increases closer to the support 207, and many shear supports are placed there. Therefore, cutting closer to the end increases the amount of shear reinforcement. Also, the amount of shear reinforcement increases as the distance of the horizontal cut increases. Generally, the amount of shear reinforcement is greater at locations adjacent to the cutting section B to be cut.

[0044] The shear reinforcement structure 300 having the above configuration eliminates the problem of approximately horizontal displacement between the concrete deck slab 202 and the main girder 201, even when the existing headed studs 2011 in the cutting section B are cut while general vehicles are passing through. Therefore, the cutting surface formation process can be carried out while general vehicles are passing through without restricting the driving load or restricting the driving lane, thereby shortening the time of construction traffic restrictions associated with deck slab replacement work and minimizing the impact on existing traffic.

[0045] As a reinforcing member 301 constituting the shear reinforcement structure 300, for example, in Figures 4(b) and 4(c), a carbon fiber sheet 302 is used and fixed to both sides of the haunch portion 204, sandwiching the web of the main girder 201. The method of fixing may be any; it may be fixed uniformly to the reinforcement range D, or it may be fixed intermittently. The carbon fiber sheet 302 may be removed after the cut surface formation process is completed in the adjacent cut section B, or it may be left as is. If it is left as is, as shown in Figure 2(b), when the cut surface formation process is performed on the cut section B where the carbon fiber sheet 302 was left, it can be cut together with the haunch portion 204.

[0046] Figure 5(a) also shows an example where post-installed anchors are used as reinforcing members 301. Specifically, anchor bolts 303 are inserted through pilot holes 204b extending from the haunch section 204 to the concrete deck slab 202 and through holes (not shown) provided in the upper flange of the main girder 201, and these anchor bolts 303 are embedded and fixed in adhesive 304 filled into the pilot holes 204b. The anchor bolts 303 are provided in pairs on both sides of the web of the main girder 201, and multiple bolts are installed with spacing between them in the bridge axis direction relative to the reinforcement area D.

[0047] Any type of post-installed anchor available on the market can be used, but those that can be removed after use are preferred. The ability to remove the anchor can be achieved, for example, by applying a special coating 305 to the embedded portion of the anchor bolt 303 in the pilot hole 204b, as shown in Figure 5(b), and by using acrylic resin for the adhesive 304.

[0048] This allows the anchor bolts 303 to be quickly removed after the cut surface formation process is completed in cut section B. Furthermore, the pilot holes 204b after removal can be used when installing the composite jig 306 used to create the composite structure 100 in the recombination process, thereby saving labor.

[0049] Furthermore, Figure 5(c) shows an example where a composite jig 306 is used as the reinforcing member 301. The composite jig 306 is a member used when forming the composite structure 100 as shown in Figures 1(c) and 2(c). Details are left to Japanese Patent Application Publication No. 2021-25288, but it is installed after the lower surfaces of the haunch portions 204 on both sides of the web of the main girder 201 have been shaped, and the composite jig 306 has a plane that contacts this shaped surface and the lower surface of the upper flange of the main girder 201.

[0050] The composite jig 306 with this configuration can be fastened with fasteners 307 such as bolts after being brought into contact with both the shaping surface provided on the haunch portion 204 and the lower surface of the upper flange of the main girder 201. The composite jigs 306 are installed in pairs on both sides of the web of the main girder 201, thereby forming the shear reinforcement structure 300. These composite jigs 306 may be installed in one location within the reinforcement range D, or multiple jigs may be arranged with spacing in the bridge axis direction. Furthermore, any shape of the structure can be adopted as long as it is usable for the composite structure 100.

[0051] This allows the composite jig 306 to be removed after the cut surface formation process is completed in cut section B and reused in the recombination process. This significantly reduces the number of components required for the deck slab replacement method, contributing to cost reduction.

[0052] The shear reinforcement structure 300 described above may be installed adjacent to each of the cut sections B before the cut surface formation process is carried out, without conducting a safety analysis of the bridge 200. However, depending on the construction conditions, such as the location of the cut sections B on the main girder 201, it may not always be necessary to install it. For this reason, it is advisable to verify the necessity of the shear reinforcement structure 300 for each cut section B based on the results of the safety analysis.

[0053] ≪≪Safety analysis≫≫ Safety analysis is a structural analysis (e.g., 3D FEM analysis) conducted to confirm safety at each construction stage during the bridge deck replacement work. Therefore, it reflects various construction conditions such as the structure and type of bridge 200, as well as the replacement work plan formulated when implementing the bridge deck replacement method in construction area A.

[0054] <<<Replacement Work Plan>>> The replacement work plan, as mentioned above, is a step-by-step process that outlines the tasks to be performed from the time the construction area A and cutting section B are defined until the replacement process of the concrete slab 202 is completed in all cutting sections B within construction area A.

[0055] For example, Figure 6 shows steps 1-16, Figure 7 shows steps 1-13, Figure 8 shows steps 1-19, Figure 9 shows steps 1-12, and Figure 10 shows steps 1-26, illustrating a plan to complete the concrete slab replacement process for all cut sections B and replace the slab within construction area A with a new slab 206. As can be seen from these, the location and distance of the cut surface formation process, the remaining state of the concrete slab 202, and the update status of the new slab 206 differ at each step.

[0056] Therefore, after formulating a replacement work plan for construction area A, a safety analysis will be conducted for each construction step. This will make it possible to provide construction personnel with highly accurate analysis results that reflect the replacement work plan, regardless of which replacement work plan is used to carry out the deck replacement work. Consequently, the necessity of safety measures can be examined based on the analysis results, and if it is determined that safety measures are unnecessary, the reinforcement process can be omitted.

[0057] The above replacement work plan can be broadly classified into three cases depending on the timing of the replacement process for the concrete slab 202, which requires construction traffic restrictions, for the multiple cut sections B within the construction area A. As shown in Figure 11, the three cases will be explained using the example of dividing the construction area A into six cut sections B and two end sections BE.

[0058] In Figure 11, an example is given where the construction area A includes the vicinity of the support point 207 of the main girder 201, and a predetermined area adjacent to this support point 207 is set as the end section BE. Generally, in the composite girder bridge given as an example of bridge 200, the shear force increases closer to the support point 207, so headed studs 2011 are often added in this area compared to the middle section of the main girder 201. For this reason, the area where these headed studs 2011 are added is separately set as the end section BE.

[0059] Case 1 involves designating all cut sections B within construction area A as a single replacement group C, and planning to simultaneously replace the concrete slab 202 in all cut sections B. Figures 6 and 7 are examples of Case 1.

[0060] Case 2 involves dividing multiple consecutive cutting sections B within construction area A into multiple replacement groups C1, C2, C3, etc., and planning to carry out the replacement process for each of these replacement groups C1, C2, C3, etc. For example, in Case 2-1, the cutting sections B within construction area A are divided into two groups, and the plan is to carry out the replacement process once for each replacement group C1 and C2, for a total of two times. Figure 8 is an example of this plan.

[0061] Case 2-2 involves dividing the cutting sections B within the construction area A into three groups and performing the replacement process once for each replacement group C1, C2, and C3, for a total of three times. Figure 9 shows an example of this plan. Case 3 involves not setting replacement groups and performing the replacement process for each cutting section B within the construction area A. Figure 10 shows an example of this plan.

[0062] Specifically, in Figure 6, which is an example of Case 1, the reinforcement process, cut surface formation process, and recombination process are carried out sequentially starting from the leftmost cut section B of the main girder 201 (steps 2-13), and then the cut surface formation process is carried out for the end sections BE on both sides (step 14). After that, the concrete deck slab 202 replacement process is carried out simultaneously (steps 15-16).

[0063] In Figure 7, another example of Case 1, the cutting section B located in the center of the main girder 201 is first subjected to a cutting surface formation process and a recombination process (steps 2-4). Next, the cutting sections B located on the left and right sides of the main girder 201 are sequentially subjected to a reinforcement process, a cutting surface formation process, and a recombination process (steps 4-10). After the cutting surface formation process is performed on the end sections BE on both sides (step 11), the concrete slab 202 is replaced simultaneously (steps 12-13).

[0064] Furthermore, in Figure 8, which is an example of Case 2-1, the reinforcement process and replacement process are carried out first in replacement group C1 located to the left of main girder 201 (steps 2-11), and then the reinforcement process and replacement process are carried out in replacement group C2 located to the right of main girder 201 (steps 11-19).

[0065] In Figure 9, which is an example of Case 2-2, the replacement group C1 located in the center of the main girder 201 is carried out first, from the cut surface formation process to the replacement process (steps 2-6). Then, in parallel, the replacement groups C2 and C3 located on the left and right sides of the main girder 201 are carried out, from the reinforcement process to the replacement process (steps 6-12).

[0066] Then, in Figure 10, which is an example of Case 3, after performing the reinforcement process, the cut surface formation process and the recombination process at the leftmost cut section B of the main girder 201, the replacement process is carried out together with the end section (steps 2-6). After that, the reinforcement process, the cut surface formation process and the recombination process are repeated sequentially for the remaining cut sections B (steps 6-22). Then, after performing the cut surface formation process and the recombination process at the rightmost cut section B of the main girder 201, the replacement process is carried out together with the end section BE (steps 23-26).

[0067] Furthermore, as shown in steps 2-3 of Figure 7 and steps 2-3 of Figure 9, when the cut surface formation process is carried out first in the central cut section B of the main girder 201, a shear reinforcement structure is not provided. This is because, generally, the shear force of a composite girder is greater closer to the support points 207. In other words, since the shear force is small in the intermediate section between the support points 207, the reinforcement process is not included in the construction steps. Also, as shown in step 12 of Figure 6 and step 8 of Figure 7, when the cut surface formation process is carried out in the cut section B adjacent to the end section BE of the main girder 201, a shear reinforcement structure is not provided. This is because, as mentioned above, the end section BE has more headed studs 2011 compared to the cut section B. However, if it is determined that safety measures are necessary after conducting a safety analysis, a reinforcement process can be added.

[0068] ≪≪Detailed flow of the floor slab replacement method incorporating a floor slab cutting method≫≫ After conducting the safety analysis described above and examining the necessity of safety measures (installation of shear reinforcement structure 300) at each construction step, the procedure for implementing the deck slab replacement method will be explained using Figure 8, which corresponds to Case 2-1 of the replacement work plan, as an example, following the flow chart in Figure 3.

[0069] ≪≪Cutting process≫≫ ≪Method for cutting the deck slab: Planned process≫ As shown in step 1 of Figure 8, the construction area A is set to encompass the entire area between the support points 207, and the construction area A is further divided at the positions of the opposing brace 203 and the crossbeam 205, creating a total of six cutting sections B1 to B6. In addition, since both ends of the construction area A are adjacent to the support points 207, these areas are set as end sections BE1 and BE2. Based on this, a replacement construction plan is formulated.

[0070] The details of the replacement construction plan are as follows: Cut sections B1 to B6 and end sections BE1 and BE2 will be divided into two replacement groups C1 and C2, separated by the 205 beam. Work will begin with replacement group C1 first and the replacement process will be completed, after which work will begin with replacement group C2. In other words, the replacement process, which will involve construction traffic restrictions, will be carried out twice within construction area A.

[0071] Within replacement group C1, as shown in steps 2 to 11, the reinforcement process, cut surface formation process, and recombination process are completed sequentially starting from the leftmost cut section B1 of the main girder 201, after which the cut surface formation process for end section BE1 is carried out. After this, the replacement process is carried out simultaneously from end section BE1 to cut section B3.

[0072] Within replacement group C2, as shown in steps 11-19, the reinforcement process, cut surface formation process, and recombination process are completed sequentially starting from the cut section B4 located in the center of the main girder 201, after which the cut surface formation process for the end section BE2 is carried out. After this, the replacement process is carried out simultaneously from cut section B4 to end section BE2.

[0073] A safety analysis reflecting the above replacement construction plan will be conducted for each construction step, and the necessity of safety measures will be verified based on the analysis results. In this embodiment, it was determined that no safety measures were necessary in Step 15, when the cut surface formation process is carried out in the cut section B6.

[0074] <<<Replacement Group C1>>> ≪Cutting process: Reinforcement process and cut surface formation process≫ First, with general vehicle traffic open, a shear reinforcement structure 300 is installed adjacent to the cut section B1 within replacement group C1 (step 2). The shear reinforcement structure 300 may employ any of the reinforcing members 301 exemplified in Figures 4 and 5.

[0075] Next, with general vehicle traffic still permitted, the cut surface formation process is carried out on the cut section B1 (step 3). During the work, as shown in Figure 2(b), fillers 401 (e.g., cambers, etc.) may be installed as needed to transmit the compressive force from the concrete slab 202 to the main girder 201.

[0076] ≪≪Resynthesis process≫≫ After this, the recombination process is carried out in the cut section B1 while general vehicle traffic remains open (step 4). For the composite structure 100, it is preferable to use a composite jig 306 that can be used as a reinforcing member 301 that constitutes the shear reinforcement structure 300 shown in Figure 5(c). Details of the composite structure 100 including these composite jigs 306 and the procedure thereof are referred to Japanese Patent Application Publication No. 2021-25288.

[0077] While maintaining the opening of the road to general traffic, the reinforcement process, cut surface formation process, and resynthesis process described above are sequentially and repeatedly carried out in each of the cut sections B2 and B3 included in replacement group C1 (steps 5-8). As a result, cut sections B1, B2, and B3 become ready for the replacement process to be carried out as well.

[0078] <<<Replacement Process>>> Since replacement group C1 includes the end section BE1, traffic restrictions for general vehicles are implemented, and the cut surface formation process is carried out on the end section BE1 (step 9). After this, the replacement process is carried out simultaneously within replacement group C1 (steps 10-11). At this time, as shown in Figure 2(d), it is advisable to install a load transfer jig 402 between the newly installed deck slab 206 and the remaining concrete deck slab 202.

[0079] Any load transmission jig 402 capable of transmitting compressive force (shear force may or may not be transmitted) between the remaining concrete slab 202 and the newly constructed slab 206 may be used. If a mechanism for transmitting shear force or axial force is required, these should be provided separately.

[0080] After the replacement process within replacement group C1 is completed using the procedure described above, general vehicle traffic will be reopened. As shown in step 9, the end section BE1 is carried out in conjunction with the replacement process which involves restricting general vehicle traffic, thus limiting the construction traffic restrictions within replacement group C1 to just one instance.

[0081] <<<Replacement Group C2>>> <<Cutting process: Reinforcement process and cut surface formation process>> After the work in replacement group C1 is completed, the reinforcement process, cut surface formation process, and re-synthesis process are repeatedly carried out sequentially on cut sections B4 and B5 using the same procedure as above, while keeping the road open to general traffic (steps 11-15). Next, the reinforcement process is omitted for cut section B6, which is deemed not to require safety measures, and the cut surface formation process and re-synthesis process are carried out (steps 15-16). As a result, cut sections B4, B5, and B6 are ready for the replacement process to be carried out as well.

[0082] <<<Replacement Process>>> Since replacement group C2 includes end section BE2, traffic restrictions for general vehicles are implemented, and the cut surface formation process is carried out on end section BE2 (step 17). After this, the replacement process is carried out simultaneously within replacement group C2 (steps 18-19).

[0083] Following the above procedure, the deck replacement work within construction area A will be completed, and general vehicle traffic will be reopened. As shown in step 17, the end section BE2 will be carried out in conjunction with the replacement process which will restrict general vehicle traffic, thus limiting the construction traffic restrictions within replacement group C2 to just one instance.

[0084] According to the deck replacement method described above, by employing a deck cutting method in the cutting process, it is possible to ensure a period of general vehicle traffic access during the cutting process. Therefore, in the deck replacement method, the only process that requires construction traffic restrictions is the replacement of the concrete deck slab 202. This increases the flexibility of the work process and improves constructability.

[0085] The method for cutting a deck slab, the method for replacing a deck slab, and the shear reinforcement structure of the present invention are not limited to the above embodiments, and various modifications are possible without departing from the spirit of the present invention.

[0086] For example, in this embodiment, a composite I-girder bridge as shown in Figures 1(a) and 2(a) is given as an example of bridge 200. However, it is not limited to this, and any structure and type of bridge 200 in which a concrete deck slab 202 and a steel main girder 201 are joined via joints can be adopted, such as a box girder, a non-composite type bridge, or a continuous girder bridge.

[0087] Furthermore, as shown in Figure 1(a), the construction area A is defined as an area that includes only one main girder 201 in the direction perpendicular to the bridge axis, but it is not limited to this, and may include multiple main girders 201. In this case, the reinforcement process, the cut surface formation process, and the recombination process may be carried out sequentially for each main girder 201, or they may be carried out in parallel for multiple main girders 201.

[0088] Furthermore, the safety analysis performed during the deck cutting process is conducted to confirm safety during construction, as mentioned above. Therefore, a separate safety analysis will be conducted after the completion of the deck replacement work. If the analysis determines that safety measures are necessary, reinforcing structures will be installed at the necessary locations on the main girder 201 as a pre-treatment step before the deck cutting process is carried out.

[0089] Furthermore, the reinforcing structure to be installed for the main girder 201 should be selected and adopted from among the reinforcing structures that have been conventionally used in deck slab replacement work, etc., as appropriate. In addition, the method used for safety analysis after the completion of construction should be a structural analysis method that is commonly used (for example, 3D FEM analysis, etc.) as appropriate.

[0090] Furthermore, in this embodiment, the case in which a recombination process is performed on the cut section B is given as an example. However, if the concrete slab 202 replacement process is performed individually for each cut section B within the construction area A, as shown in Figure 10, the recombination process may be omitted.

[0091] In addition, in this embodiment, when safety measures are required, the reinforcement process is carried out immediately before the cut surface formation process is carried out in the cut section B, and the shear reinforcement structure 300 is installed. However, the reinforcement process may be carried out at any stage as long as the effects of installing the shear reinforcement structure 300 can be obtained. For example, the reinforcement process may be carried out in advance for all cut sections B within the construction area A where safety measures are required, and the shear reinforcement structure 300 may be installed.

[0092] Furthermore, the reinforcing members 301 constituting the shear reinforcement structure 300 can be made from various materials other than the carbon fiber sheets 302 and composite jigs 306 described with reference to Figures 4 and 5. Below, we will give examples of cases where post-installed anchors using steel plates 310 for mechanical joining are used as reinforcing members 301, and cases where adhesive steel plates 312 are used, and explain the details of each.

[0093] Figure 12(a) shows a case in which a post-installed anchor is used as the reinforcing member 301, which is provided to be enclosed within the haunch portion 204 using a steel plate for mechanical joining 310. As shown in Figure 12(b), the steel plate for mechanical joining 310 is a thick steel plate with a rectangular shape in plan view and multiple holes, through which an anchor bolt 309 is inserted 3101 and an insertion hole 3102 is inserted 308.

[0094] Any bolt material may be used for the stud bolt 308, preferably a bolt material that can be reused as a fastener to fix the composite jig 306, as described with reference to Figure 5(c), when it is used in the recombination process. The steel plate 310 for mechanical joining is provided via this stud bolt 308 on the lower surface side of the upper flange of the main girder 201, as shown in Figure 12(a), with a portion of it protruding from the upper flange. An insertion hole 3101 through which an anchor bolt 309 is inserted is located in this portion protruding from the upper flange.

[0095] As shown in Figure 12(a), the through hole 3101 is provided in a range that prevents the anchor bolt 309 from interfering with the upper flange edge surface (vertical surface) of the main girder 201 when the anchor bolt 309 is passed through, and also prevents interference with the pilot hole 204b extending from the haunch portion 204 to the concrete slab 202. The pilot hole 204b is a hole for fixing the anchor bolt used when installing the composite jig 306, which was explained with reference to Figure 5(c), during the recombination process.

[0096] As shown in Figure 12(c), the anchor bolt 309 inserted through the through hole 3101 is secured by inserting one end into a pilot hole 204c provided in the haunch portion 204. The pilot hole 204c extends to a depth corresponding to the concrete slab 202, and the anchor bolt 309 has a length that corresponds to this depth.

[0097] Furthermore, the other end of the anchor bolt 309 is fixed to the steel plate 310 for mechanical joining in a manner known as bolt joining. For this reason, a countersunk washer 311 is interposed to prevent any gap from forming between the anchor bolt 309 and the through hole 3101. This prevents any looseness in the approximately horizontal direction that could occur due to a gap between the two.

[0098] The combination of anchor bolts 309, stud bolts 308, and mechanical joining steel plates 310 described above is provided in pairs on both sides of the web of the main girder 201, as shown in Figure 12(a). In addition, multiple such combinations are installed at intervals in the bridge axis direction relative to the reinforcement area D, as shown in Figure 4(a). This forms a shear reinforcement structure 300 adjacent to the cut section B before the cutting and separation process is carried out.

[0099] In this embodiment, as shown in Figures 12(b) and (c), two anchor bolts 309 are provided for the steel plate 310 for mechanical joining. However, any number of bolts is acceptable as long as it is possible to provide sufficient reinforcement to compensate for the substantially horizontal shear force that is lacking when the headed stud 2011 located in the cutting section B, as shown in Figures 4(a) and (b), is cut. For example, increasing the number of anchor bolts 309 makes it possible to reduce the diameter of the anchor.

[0100] Furthermore, any type of anchor bolt 309 used for post-installed anchors can be used, and for example, those that have a function that allows them to be removed after use, as explained with reference to Figure 5(b), are preferred. In addition, the shape and size of the steel plate 310 for mechanical joining can be any, as long as it has a plate thickness that ensures the shear force between the anchor bolt 309 and the stud bolt 308.

[0101] Figure 13(a) shows a case where a steel plate 312 for attachment is used as the reinforcing member 301 and is attached to the side surface of the haunch portion 204. The steel plate 312 for attachment is made by bending a thin steel plate and is formed to continuously follow both the lower surface of the upper flange of the main girder 201 and the side surface of the haunch portion 204. As shown in Figure 13(b), it is formed in a rectangular shape in plan view and has multiple holes, forming through holes 3121 through which anchor bolts 314 are inserted and through holes 3122 through which stud bolts 308 are inserted.

[0102] Any bolt material may be used for the stud bolt 308, preferably a bolt material that can be reused as a fastener to fix the composite jig 306, as described with reference to Figure 5(c), when it is used in the recombination process. The adhesive steel plate 312 is installed on the lower surface of the upper flange of the main girder 201 via this stud bolt 308, as shown in Figure 13(a).

[0103] In the adhesive steel plate 312, adhesive 313 is applied to the area along the side surface of the haunch portion 204 that protrudes from the upper flange, and through holes 3121 through which anchor bolts 314 are inserted are provided. As a result, the adhesive steel plate 312 is fixed to the side surface of the haunch portion 204 via the adhesive 313 and anchor bolts 314.

[0104] The above-described combination of adhesive steel plate 312, adhesive 313, stud bolt 308, and anchor bolt 314 is provided in pairs on both sides of the web of the main girder 201. In addition, multiple combinations are installed with spacing in the bridge axis direction relative to the reinforcement area D, as shown in Figure 4(a). This forms a shear reinforcement structure 300 adjacent to the cut section B before the cutting and separation process is carried out.

[0105] The anchor bolts 314 are intended to temporarily fix the steel plate 312 to the haunch portion 204 until the adhesive 313 develops its adhesive effect, and to prevent the steel plate 312 from peeling off after the adhesive has hardened. For this reason, they may be omitted depending on the adhesive 313. When anchor bolts 314 are used, any type used for post-installed anchors can be used, but those that have a function that allows them to be removed after use, as explained with reference to Figure 5(b), are preferred.

[0106] Furthermore, the adhesive 313 is not limited in any way as long as it is a material that conforms well to both the side surface of the concrete haunch portion 204 and the steel plate 312 to which it is attached, and is capable of providing reinforcement that is sufficient to compensate for the substantially horizontal shear force that is lacking when the headed stud 2011 located in the cutting section B, as shown in Figures 4(a) and (b), is cut. Therefore, it may be applied to the steel plate 312 in advance, or a double-sided tape type may also be used.

[0107] Alternatively, the adhesive steel plate 312 can be fixed to the side of the haunch portion 204 using stud bolts 308 and anchor bolts 314, and then an injectable adhesive 313 can be injected between them. Furthermore, the area of ​​the adhesive steel plate 312 that runs along the side of the haunch portion 204 may be subjected to surface treatment such as blasting or painting, as well as cleaning. This makes it possible to adjust the adhesion strength in advance between the surface treatment and the adhesive 313.

[0108] The reinforcing member 301, which uses the adhesive steel plate 312 described above, may be left as is if its installation position does not interfere with the planned installation position of the synthesis jig 306 in the resynthesis process. If left as is, the adhesive steel plate 312 can be cut together with the haunch portion 204 when the cut surface forming process is performed on the cut section B where it was left. [Explanation of symbols]

[0109] 100 Synthetic Structure 200 bridges 201 Main girder 2011 Studs with Heads 202 Concrete slab 203 Opposite Inclination 204 Haunch part (joint part) 204a Cut surface 204b Pilot hole 204c pilot hole 205 Horizontal girder 206 Newly constructed deck (new deck) 207 Fulcrum (Support) 300 Shear reinforced structure 301 Reinforcement member 302 Carbon Fiber Sheet (Sheet Material) 303 Anchor bolt (bolt material) 304 Adhesive 305 Special Coating 306 Synthesis jig 307 Fasteners 308 Stud bolts 309 Anchor bolts 310 Steel plate for mechanical joining 3101 Through hole (for anchor bolts) 3102 Through hole (for stud bolts) 311 Dish-cut washer 312 Steel plate for pasting 3121 Through hole 3122 Through hole 313 Adhesive 314 Anchor bolts 401 Filling 402 Load transmission jig A. Scope of work B Cut section BE end section C Replacement Group D Reinforcement range

Claims

1. A method for cutting a bridge deck, which involves cutting and separating the concrete deck slab and the main girder at the joint, A reinforcement step involves providing a shear reinforcement structure adjacent to the cut section set at the joint in the bridge axis direction, A cutting surface forming step in which a cutting surface substantially parallel to the main girder is formed in the aforementioned cutting section, A method for cutting a floor slab, characterized by comprising the following:

2. In the method for cutting a floor slab according to claim 1, The steps include setting a construction area at the joint, dividing the construction area into sections to set multiple cutting sections, The process of formulating a work procedure, which includes the cutting surface formation process and the replacement process for replacing the cut and separated concrete slab, to be carried out for the aforementioned cutting section, as a replacement work plan within the construction area, A step of conducting a safety analysis that reflects the replacement work plan, A method for cutting a floor slab, characterized by comprising a planning process having the following:

3. A deck replacement method for replacing the concrete deck slab installed on the main girder of a bridge, A cutting step of cutting the concrete floor slab and the main girder at the joint portion, according to the floor slab cutting method described in claim 1, The replacement process involves removing the aforementioned concrete slab and replacing it with a new slab. A floor slab replacement method characterized by having the following features.

4. A deck replacement method for replacing the concrete deck slab installed on the main girder of a bridge, A cutting step of cutting the concrete floor slab and the main girder at the joint portion, according to the floor slab cutting method described in claim 2, The process includes removing the aforementioned concrete slab and replacing it with a new slab, A floor slab replacement method characterized by carrying out the cutting step and the replacement step based on the replacement work plan.

5. In the floor slab replacement method according to claim 3 or 4, The recombination step includes a recombination step in which the concrete floor slab and the main girder, which were cut and separated in the cutting step, are recombined using a detachable composite jig. A floor slab replacement method characterized by removing the composite jig together with the concrete floor slab in the replacement step.

6. A shear reinforcement structure used in the method for cutting a floor slab according to claim 1 or 2, A shear reinforcement structure characterized by comprising a reinforcing member installed across the concrete slab and the main girder at a position adjacent to the aforementioned cut section.

7. In the shear reinforcement structure according to claim 6, A shear reinforcement structure characterized in that the reinforcing member is a sheet material fixed to the side surface of the joint.

8. In the shear reinforcement structure according to claim 6, A shear reinforcement structure characterized in that the reinforcing member comprises a bolt material enclosed within the joint.

9. In the shear reinforcement structure according to claim 6, The shear reinforcement structure is characterized in that the reinforcing member is installed on the side of the joint and comprises a composite jig capable of recombining the cut and separated concrete floor slab and the main girder.

10. In the shear reinforcement structure according to claim 6, The reinforcing member is a steel plate for mechanical joining that is installed on the main girder, A bolt material that penetrates the steel plate for mechanical joining and is enclosed within the joint, A shear reinforcement structure characterized by having the following features.

11. In the shear reinforcement structure according to claim 6, A shear reinforcement structure characterized in that the reinforcing member comprises a steel plate for adhesion that is attached to the side surface of the joint.

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