How to select components for temporary support brackets

Abstract

To provide a temporary receiving bracket for a steel girder capable of reducing a cost by reusing the same without discarding after the completion of construction.SOLUTION: A temporary receiving bracket installed on a bridge pier of a bridge to be constructed to temporarily receive a load of a steel girder, comprises: a widening bracket having a predetermined strength and an inverted L shape in a side view, the widening bracket being fixed to a side surface of the bridge pier below the steel girder with an anchor bolt; a height adjusting member installed between the lower surface of the steel girder and the upper flange of the widening bracket; one overhang bracket among a number of overhang brackets of different sizes and strengths which are joined to a side surface of a main steel plate in the vertical direction constituting the steel girder; one connecting auxiliary steel member among a number of connecting auxiliary steel members of different sizes that are interposed between the main steel plate of the steel girder and the overhang bracket and that connect the overhang bracket to the main steel plate; and one splice plate among a number of splice plates for connecting the overhang bracket and the connecting auxiliary steel members.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a temporary support bracket and bracket selection method for steel girders used in construction such as earthquake-resistant reinforcement and repair of steel bridges, and in particular to a temporary support bracket and bracket selection method for a combination of an expansion bracket and an overhang bracket. [Background technology]

[0002] During earthquake-resistance reinforcement or repair work on steel bridges, if the bridge is significantly deformed or the repair involves replacing the shoe seat (replacement of bearings), the load of the steel girder (bridge girder) must be supported by height adjustment materials or jacks. In such cases, if there is insufficient installation area for the height adjustment materials or jacks on the top surface of the pier, or if the girder support length is insufficient, a steel temporary support bracket called an expansion bracket is installed on the side of the pier directly below the girder in order to widen the edge. However, since the steel bridges that are the subject of construction each have different dimensions and also differ in conditions such as the height of the steel girders, dead load (static load), and live load, in the past, temporary support brackets were designed for each steel bridge. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2002-212916 A Summary of the Invention [Problem to be solved by the invention]

[0004] Conventional temporary support brackets were designed for each steel bridge, so preparation work before construction began took time, and they were removed and discarded after construction was completed, resulting in unnecessary costs. In addition, conventional temporary support brackets were one piece, so they were difficult to handle manually, and there was an issue that heavy machinery was required for large-scale construction. It should be noted that there is an invention relating to widening brackets, such as that in Patent Document 1, in which the bolts in the top row that secure the bracket to the side of the concrete pier are anchor bolts, and the bolts in the second row and below are shorter, drive-in anchor bolts. However, this invention is designed to reduce interference with reinforcing bars when drilling bolt holes, and has a different problem from the present invention.

[0005] The present invention has been made with attention to the above-mentioned problems in mind, and its purpose is to provide a temporary support bracket for steel girders that does not require redesigning from scratch for each steel bridge that is the subject of construction, and that can reduce costs by being reused rather than discarded after construction is completed. Another object of the present invention is to provide a temporary support bracket for a steel girder that can be handled by human strength and allows construction work to be carried out without using heavy machinery. It is still another object of the present invention to provide a bracket selection method capable of shortening the preparation period before the start of construction work. [Means for solving the problem]

[0006] In order to solve the above problems, the present invention provides A temporary support bracket that is installed on the pier of the bridge under construction to temporarily support the load of the steel girder. An inverted L-shaped widening bracket having a predetermined strength fixed to a side surface of the pier below the steel girder with an anchor bolt; A height adjustment member installed between the lower surface of the steel girder and the upper flange of the widening bracket; One of a plurality of protruding brackets having different sizes and strengths that are connected to a side surface of the vertical main steel plate constituting the steel girder; One connecting reinforcing steel member among a plurality of connecting reinforcing steel members having different sizes, which is interposed between the main steel plate and the overhang bracket of the steel girder and connects the overhang bracket to the main steel plate; The connecting bracket is configured to include one splice plate among a plurality of splice plates that connect the protruding bracket and the connecting reinforcement steel material.

[0007] With the above-mentioned configuration, temporary support brackets suitable for steel bridges of different sizes can be constructed during construction such as the repair of steel bridges, and since there is no need to redesign the temporary support brackets from scratch for each steel bridge that is the subject of construction, the preparation period before construction can be shortened, and costs can be reduced by reusing the brackets after construction is completed rather than discarding them. Also, since the temporary support brackets are composed of widening brackets and overhanging brackets, they can be handled by hand, and construction can be carried out without using heavy machinery. Furthermore, since the temporary support bracket is composed of an expansion bracket and an overhang bracket, the reaction force from the expansion bracket, which receives the load of the steel girder instead of the support part (shoe seat), can be distributed by the overhang bracket and transmitted to the main steel plate of the steel girder in the vertical direction, thereby preventing the steel girder from being subjected to forces or moments different from normal times, causing deformation.

[0008] Here, preferably, the connecting steel member is made of an L-shaped angle bar, One side of the L-shaped angle material is connected to the main steel plate of the steel girder by a bolt and a nut, The other side of the L-shaped angle bar is configured to be connected by a bolt and a nut to the splice plate which is connected by a bolt and a nut to the vertical plate portion of the projection bracket. According to this configuration, the overhang bracket can be connected to the main steel plate of the steel girder by bolts and nuts via the connecting steel member and the splice plate, which makes it possible to flexibly respond to cases where the height of the steel girders that make up the bridge to be constructed is different.

[0009] Furthermore, preferably, when the load received by the temporary support bracket is greater than a specified value or when the girder length of the bridge to be constructed is longer than a specified value, two expansion brackets of the same type are fixed side by side to the side of the pier below the steel girder. With this configuration, it is possible to accommodate cases where the temporary support bracket is subjected to a large load, and it is also possible to reduce the number of types of widening brackets that need to be prepared in advance, making it easier to manage the parts that make up the temporary support bracket and reducing the space required to store the parts.

[0010] Other aspects of the present application Akira teeth, The device comprises: an expansion bracket having a predetermined strength and a main body part having an inverted L shape in a side view, which is fixed to the side of a pier below a steel girder with an anchor bolt; a height adjustment member installed between the lower surface of the steel girder and the upper flange of the expansion bracket; an extension bracket connected to the side of a main steel plate in the vertical direction constituting the steel girder; a connecting reinforcement member interposed between the main steel plate of the steel girder and the extension bracket and connecting the extension bracket to the main steel plate; and a splice plate connecting the extension bracket and the connecting reinforcement member; and the device is used for temporarily supporting the load of a steel girder by being installed on a pier of a bridge to be constructed. Used to construct a temporary support bracket Components In advance, For each component Prepared A group of parts that are different in size and strength From among each Select Temporary support Bracket Components Selection method Yes hand, The plurality of part groups include at least a part group of an overhang bracket, a connecting reinforcing steel member, and a splice plate, A first step of determining whether or not the girder height of a bridge to be constructed is greater than a predetermined value; A second step of determining whether the temporary support bracket to be installed needs to temporarily support a live load; A third step is to determine whether or not there is a girder drawing of the bridge to be constructed and the drawing number is known; A fourth step of determining whether the bridge to be constructed is a diagonal girder; a fifth step of calculating a temporary support reaction force to be supported by the temporary support bracket using a predetermined reaction force calculation formula when the first step determines that the girder height is greater than a predetermined value, the second step determines that temporary support of a live load is necessary, the third step determines that the drawing number is known, and the fourth step determines that the girder is not an oblique girder; Using a bracket selection sheet that was created in advance based on the temporary support reaction force calculated in the fifth step and the girder length of the bridge to be constructed, Parts From among 、 The extension brackets, connecting steel members, and splice plates to be used One of each A sixth step of selecting; Including, The bracket selection sheet has a type classification value related to the load of the temporary support reaction force and a type classification value related to the girder length, with the temporary support reaction force and the girder length as factors. A two-dimensional pattern diagram showing the selection area of ​​the target part on an orthogonal coordinate system with the two factors as the X and Y coordinates. and At least one that corresponds to the overhang bracket is prepared in advance.This is designed to allow this.

[0011] According to the above-mentioned method, it is possible to select a part having an appropriate strength and size from among a plurality of components of the temporary support bracket prepared in advance, thereby shortening the preparation period before the start of construction. Part The overhang bracket is prefabricated A selection sheet consisting of a two-dimensional pattern diagram showing the selection area of ​​the target part on a Cartesian coordinate system Since the brackets are selected using the same method, it is easy to select the brackets with the appropriate strength and size. Once the brackets to be used are decided, the connecting steel members and splice plates to be used with the brackets can also be selected. Selection It is possible.

[0012] In addition, it is preferable to provide a seventh step of judging whether or not there is a space to install a jack on the top surface of the pier of the bridge to be constructed when it is determined in the fourth step that the pier is not an oblique girder, and when it is determined in the seventh step that there is a space to install a jack, it is determined not to use a widening bracket, and There is no If it is determined that the width-enlarging bracket is to be used, the sixth step is executed. According to this method, if there is room to install a jack on the top surface of the pier of the bridge being worked on, a temporary support bracket is constructed without using an expansion bracket, and if there is not enough room to install a jack on the bridge being worked on, a temporary support bracket is constructed using an expansion bracket, so that a temporary support bracket that has sufficient strength and is efficient according to the conditions of the bridge being worked on can be constructed.

[0013] Furthermore, it is preferable that a plurality of widening brackets differing in size and strength are prepared as the widening brackets, and if it is decided in the seventh step to use the widening bracket, in the sixth step, one widening bracket to be used is selected from the plurality of widening brackets based on the temporary support reaction force calculated in the fifth step and the girder length of the bridge to be constructed. According to this method, it is possible to select an expansion bracket that constitutes an optimal temporary support bracket for the bridge being constructed. Effect of the Invention

[0014] The steel girder temporary support bracket of the present invention eliminates the need to redesign from scratch for each steel bridge that is the subject of construction, and can be reused after construction is completed instead of being discarded, thereby reducing costs. It can also be handled manually, so construction can be carried out without using heavy machinery. Furthermore, the bracket selection method of the present invention has the effect of shortening the preparation period before construction begins. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1 is a front view showing a state in which a temporary support bracket (type 1) for a steel girder according to one embodiment of the present invention is attached to a bridge. [Diagram 2] FIG. 11 is a front view showing the state in which a type 2 extension bracket of the temporary support bracket according to the embodiment is attached to a bridge. [Diagram 3] FIG. 11 is a front view showing the state in which a type 3 extension bracket of the temporary support bracket according to the embodiment is attached to a bridge. [Figure 4] 1A is a side view showing the shape of an overhang bracket that constitutes a temporary support bracket of an embodiment, and FIG. 1B is a side view showing the shape of an expansion bracket. [Diagram 5] 1A and 1B are a front view and a side view showing the shape of a connecting reinforcing steel member that constitutes a temporary support bracket of an embodiment. [Figure 6] 1A and 1B are a front view and a side view showing the shape of a splice plate that constitutes a temporary support bracket of the embodiment. [Figure 7] 13 is a diagram showing an example of a bracket selection sheet (monogram) used in the process of selecting a temporary bracket in the embodiment. FIG. [Figure 8] 10 is a flowchart showing the steps of a specific method for selecting the expansion bracket and the overhang bracket of the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, with reference to the drawings, an embodiment of a temporary support bracket for a steel girder and a bracket selection method according to the present invention will be described. FIG. 1 is a front view showing a state in which a temporary support bracket according to an embodiment is attached to a bridge.

[0017] The temporary support bracket of this embodiment is composed of a pair of widening brackets 21A, 21B fixed to the side walls of a reinforced concrete pier to widen the apparent area of ​​the upper surface of the pier, a pair of overhang brackets 22A, 22B fixed to both sides of a vertical main steel plate 11 constituting a steel girder (bridge girder) 10, and connecting reinforcement steel members 23A, 23B and splice plates 24A, 24B interposed between the main steel plate 11 and the overhang brackets 22A, 22B. The overhang brackets 22A, 22B and the connecting reinforcement steel members 23A, 23B, and the connecting reinforcement steel members 23A, 23B and the splice plates 24A, 24B are respectively connected by bolts and nuts (31, 32), and the widening brackets 21A, 21B are fixed to the side walls of the pier by anchor bolts and nuts (33, 34).

[0018] A pair of height adjustment members 25A, 25B are placed on the upper flanges 21a, 21b of the widening brackets 21A, 21B fixed to the side walls of the pier, and a pair of height adjustment members 25A, 25B are placed between the height adjustment members 25A, 25B and the lower horizontal flanges 22a, 22b of the overhang brackets 22A, 22B. plate is inserted to adjust the height. A temporary support device for the steel girder 10 is formed by the widening brackets 21A, 21B, the overhanging brackets 22A, 22B, the connecting reinforcing steel members 23A, 23B, the splice plates 24A, 24B, and the height adjustment members 25A, 25B. With regard to live loads, the configuration described above is the basis, but if dead loads and live loads are also considered separately, a temporary support device for the steel girder 10 may be configured with hydraulic jacks 26A, 26B inserted between the lower horizontal flanges 22a, 22b and the height adjustment members 25A, 25B. One or more height adjustment plates may be inserted between the lower horizontal flanges 22a, 22b of the overhang brackets 22A, 22B and the height adjustment members 25A, 25B.

[0019] Depending on the bridge to be constructed, only the widening brackets 21A, 21B may be used, and the overhang brackets 22A, 22B, the connecting steel members 23A, 23B, and the height adjustment members 25A, 25B may not be used. As will be described later, three types of overhang brackets 22A, 22B with different sizes and strengths are prepared according to the weight of the steel girder 10, i.e., the temporary load to be supported. Also, three types of splice plates 24A, 24B with different heights according to the height of the steel girder 10 are prepared. Furthermore, two types of widening brackets 21A, 21B with different sizes and strengths are prepared.

[0020] The three types of overhang brackets 22A and 22B are prepared as type 1, which is designed to support a load of up to 200 kN x a (safety factor), type 2, which is designed to support a load of up to 400 kN x a, and type 3, which is designed to support a load of up to 800 kN x a. Specifically, the outer dimensions are designed to increase in the order of type 1, type 2, and type 3. The thickness of the steel plate constituting the bracket may be changed depending on the type. FIG. 1 shows a state in which a temporary support device is constituted using type 1 widening brackets 21A and 21B and overhang brackets 22A and 22B.

[0021] Meanwhile, Figure 2 shows a temporary support bracket with a type 2 overhang bracket attached to a bridge, and Figure 3 shows a temporary support bracket with a type 3 overhang bracket attached to a bridge. In addition, Fig. 3 shows a case where hydraulic jacks 26A, 25B are not used, and in actual bridge repair work, height adjustment is performed by inserting height adjustment members 25A, 25B or height adjustment plates between the overhang brackets 22A, 22B and the widening brackets 21A, 21B, as in Fig. 1. Also, if there is space on the top surface of the pier to place the height adjustment members 25A, 25B, the widening brackets 21A, 21B are not used, and the height adjustment members 25A, 25B are inserted between the overhang brackets 22A, 22B and the pier. Depending on the expected load, hydraulic jacks 26A, 26B may be inserted between the height adjustment members 25A, 25B and the lower horizontal flanges 22a, 22b, as in Fig. 2.

[0022] The widening bracket 21A (21B) is placed on a horizontal Department It is composed of a main body having a flange 21a (21b) and a vertical plate 21c, which has an inverted L-shape in side view, and two reinforcing pieces 21d fixed to the main body so as to form a right angle with the upper inclined flange 21a (21b) and the vertical plate 21c. The reinforcing pieces 21d are formed so that the lower end is cut obliquely in order to reduce the weight of the bracket while maintaining the necessary strength. The vertical plate portion 21c is formed with a plurality of through holes 21e for the anchor bolts, and the width-widening brackets 21A and 21B are Department The flange 21a (21b) is fixed to the pier by an anchor bolt that has been embedded in advance in the side wall of the pier and a nut that is screwed onto the anchor bolt so that the flange 21a (21b) is horizontal.

[0023] Of the two types of widening brackets 21A, 21B, one is Type 1, which is designed to support a load of up to 200 kN×a (safety factor), and the other is Type 2, which is designed to support a load of up to 400 kN×a, and Type 2 has a greater height and a greater number of anchor bolt insertion holes 21e than Type 1. When the load exceeds 400 kN×a, two Type 2 brackets are used side by side. In this specification, for convenience, the case where two brackets are used side by side is referred to as Type 3.

[0024] As shown in Figure 4(A), the extension bracket 22A (22B) is composed of a main body having a lower horizontal flange portion 22a (22b) parallel to the underside of the steel girder 12, a vertical plate portion 22c perpendicular to the steel girder 12, and an upper inclined flange portion 22d inclined at approximately 45 degrees, and vertical reinforcing piece portions 22e fixed to the front and back of the vertical plate portion 22c so as to form a right angle with the vertical plate portion 22c and the lower horizontal flange portion 22a (22b). In this embodiment, in order to reduce weight, the upper end of the vertical plate portion 22c is cut obliquely, and the upper inclined flange portion 22d is provided along the edge. Also, the vertical plate portion 21c has a plurality of insertion holes for bolts for connecting the overhang bracket to the steel girder 12.

[0025] Fig. 5 shows an embodiment of the connecting reinforcement steel members 23A and 23B, in which (A) is a front view and (B) is a side view. In this embodiment, the connecting reinforcement steel materials 23A, 23B are L-shaped angle materials made of rolled steel plate (SS400) with a thickness of 12 mm, formed to form an L shape when viewed from above, with one side 23a provided with a bolt insertion hole 23c for fixing to both side surfaces of the main steel plate 11 constituting the steel girder 12, and the other side 23b provided with a bolt insertion hole 23d for connecting the splice plates 24A, 24B. The length of the connecting reinforcement steel materials 23A, 23B is set so as to correspond to the height (between the upper and lower flanges) of the bridge girder to be joined.

[0026] Fig. 6 shows examples of splice plates 24A and 24B. In Fig. 6, (A) is a front view of a splice plate used in correspondence with small overhang brackets (types 1 and 2), and (B) is a front view of a splice plate used in correspondence with a large overhang bracket (type 3). The attachment plates 24A, 24B are made of flat rolled steel plates (SS400) having a thickness of 12 mm, and as shown in Figures 6(A) and (B), are provided with bolt insertion holes 24a for fixing them to the vertical plate portions 22c of the extension brackets 22A, 22B, and bolt insertion holes 24b for connecting them to the connecting reinforcement steel materials 23A, 23B. Two types of splice plates 24A, 24B corresponding to the small overhang brackets (types 1 and 2) in Fig. 6(A) are prepared, differing in length and number of bolt insertion holes 24a, 24b. The length of the splice plates 24A, 24B is set so as to correspond to the height of the overhang bracket 22A (22B) to be joined.

[0027] As mentioned above, by having three types of extension brackets and two types of widening brackets available for each type, temporary support brackets, which previously had to be designed and manufactured for each bridge being worked on, can now be constructed by selecting from the pre-prepared items. This shortens the time it takes to install temporary support brackets and also reduces costs by reusing them rather than disposing of them after construction is completed. In addition, because the temporary support bracket is composed of multiple parts and the weight of each part is not heavy, it can be easily transported, attached, and removed by hand, which has the advantage of eliminating the need for heavy machinery. The connecting reinforcement steel members 23A, 23B and the splice plates 24A, 24B can be formed by simply drilling holes using inexpensive commercially available products. In addition, they may be left in place after construction is completed without being removed from the bridge girder.

[0028] Next, a specific procedure for selecting the above types 1 to 3 of widening brackets and overhang brackets in construction work such as earthquake-resistant reinforcement and repair of bridges will be described with reference to the flowchart of FIG. Before starting bracket selection according to the flowchart in Fig. 8, please select the horizontal axis as shown in Fig. 7. (X axis) The girder length of the bridge is (Y axis) A temporary reaction force was applied to A component design consisting of a two-dimensional pattern diagram showing the selected area of ​​the target part on a Cartesian coordinate system. Selection sheet (This is referred to as a monogram in this specification.)In the monogram in Fig. 7, KS-18 is used as a model case, and the horizontal axis is the bridge girder length, because bracket selection is highly dependent on the support reaction force at the time of design and the girder length, and by sorting based on these two factors, it is possible to avoid situations where the strength is insufficient due to, for example, Type 1 or Type 2 being selected as a temporary support bracket for a steel girder with a temporary support load of 200kN or less but a length of over 10m.

[0029] 7, the white area A indicates the selection range of brackets of type 1, the hatched area B indicates the selection range of brackets of type 2, and the meshed area C indicates the selection range of brackets of type 3. Note that the numerical values ​​of the boundaries of each area are merely examples and are not limiting. It is advisable to create the monogram in Figure 7 for each design load of the bridge, such as KS-18, KS-16, KS-12, E-33, etc. At the time of design, the bridge was designed to enable safe operation without slowing down when the heaviest freight trains pass through, and the applicable support reaction force and applicable girder length differ slightly depending on the design load, so they must be considered separately.

[0030] In selecting brackets, as shown in Figure 8, first it is determined whether the height of the steel girders (girder height) of the bridge to be constructed is equal to or greater than a specified height (e.g., 460 mm) (Step S1). If it is determined that the girder height is less than 460 mm (Step S1: No), the process moves to Step S11, an on-site survey is carried out, and brackets are individually designed to deal with the problem. This is because for small bridges with girder heights of less than 460 mm, girder replacement is more economical than repair, and even if it is decided that repairs are necessary, simple widening brackets can often be used to address the problem, as the weight of the steel girders is not large, so the problem is dealt with individually.

[0031] On the other hand, if it is determined in step S1 that the girder height is 460 mm or more (Yes), the process proceeds to step S2, where it is determined whether or not the bridge requires temporary support including live loads. Whether or not temporary support including live loads is necessary can be determined based on the repair method and the work hours for the line section. Specifically, if the work can be carried out during the night when there are no trains, it is determined that only dead loads will be handled, meaning that temporary support including live loads is not necessary, but if the repairs cannot be completed in one night, work will be carried out while trains are running, so it is determined that temporary support including live loads is necessary. If it is determined in step S2 above that live loads do not need to be considered (step S2: No), proceed to step S15 and consider temporary supports taking into account only dead loads. Note that whether or not to use brackets (type 1) is determined depending on the site conditions.

[0032] Furthermore, if it is determined in step S2 that a temporary support including live loads is necessary (Yes), the process proceeds to step S3, where it is determined whether or not the design documents contain girder drawings for the bridge to be constructed and the drawing number is known. If it is determined here that the drawing number is unknown (step S3: No), the process proceeds to step S4, where a site survey is conducted and it is determined whether or not the drawing number can be determined from the information acquired. If it is determined in step S4 that the drawing number cannot be determined (No), the process proceeds to step S11, where a site survey is conducted and brackets are individually designed to deal with the problem.

[0033] On the other hand, if it is determined in step S4 that the drawing number can be determined (Yes) and if it is determined in step S3 that the drawing number is known (Yes), the process proceeds to step S5, where it is determined whether the steel girder of the bridge to be worked on is an oblique girder, that is, a steel girder that is hung at an angle to the river. This is because in an oblique girder, the angle of the abutment to which the connecting steel members (L-shaped angles) 23A, 23B and the widening brackets 21A, 21B are attached differs from that of a normal steel girder, and the splice plates 24A, 24B that connect the L-shaped angles and the overhang brackets must be processed according to the abutment angle of the bridge to be worked on.

[0034] If it is determined in step S5 that the girder is an oblique girder (Yes), the process proceeds to step S12, where an on-site survey is carried out to confirm the obstructing structure and measure the dimensions of the bridge such as length, span distance, and girder height. A specified reaction force calculation formula is used to calculate the temporary support reaction force and to determine the component dimensions of the temporary support device. If the drawing number is known, the design load can be known by referencing the database from the drawing number, and the sheet to be used (Fig. 7) is selected from the multiple bracket selection sheets previously created for each design load based on the design load. Then, using that bracket selection sheet, the bracket to be used is selected from brackets of types 1 to 3 based on the temporary support reaction force calculated by the reaction force calculation formula and the length of the bridge to be constructed. Note that, since a spreadsheet software (program) called a reaction force calculation sheet is provided for the calculation of the temporary support reaction force in step S12, the calculation can be performed using a computer with such a program installed.

[0035] If it is determined in step S5 that the girder is not an oblique girder (No), the process proceeds to step S6, where the information on the girder drawing in the database is used to examine the temporary support, including the live load, and then a determination is made as to whether or not there is enough room to install a jack on the girder seat (upper surface of the pier) (step S7). If there is enough room to install a jack on the girder seat (Yes), : No need for widening brackets ), proceed to step S13, input the dimensions read from the girder drawing into the reaction force calculation sheet to determine the dimensions of the temporary support device, and use the bracket selection sheet to select types 1 to 3. Overhang Select the bracket to be used from among the brackets.

[0036] On the other hand, if it is determined in step S7 that there is not enough space to install the jack on the girder base (No), proceed to step S14, enter the dimensions read from the girder drawing into the reaction force calculation sheet to determine the component dimensions of the temporary support device, and select the bracket to use from the extension brackets and widening brackets of types 1 to 3. According to the bracket selection method following the above procedure, it is possible to easily select the widening bracket and the extension bracket suitable for forming the temporary support bracket to be used in the construction work.

[0037] Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications and changes are possible. For example, in the above embodiment, the types of the overhang brackets 22A, 22B are set to three types, but the types of the overhang brackets are not limited to three types, and may be four or more types. Furthermore, if there were four or more types of extension brackets, management would become more complicated and more space would be required for storage, but by limiting it to three types, it would be possible to accommodate the construction of almost all existing bridges, and it would have the advantages of being easier to manage and requiring less space for storage.

[0038] In the above embodiment, two types of widening brackets 21A, 21B with different sizes and strengths are prepared in advance and can be used as types 1 to 3, but it is also possible to prepare only one type of widening bracket, which is type 2 in the above embodiment, and when type 1 is used as an overhang bracket, the widening bracket may be substituted with type 2. In this way, the number of types of widening brackets can be reduced while avoiding insufficient strength, making management easier and reducing the space required for storage. [Explanation of symbols]

[0039] 10 steel girders 11 Main steel plate 21A, 21B Widening bracket 22A, 22B Extension bracket 23A,23B Connected reinforcing steel material 24A,24B attachment plate 25A, 25B Height adjustment member 26A, 26B Hydraulic jack

Claims

1. A method for selecting components for a temporary support bracket comprising: an expansion bracket having a main body part shaped like an inverted L in side view and having a prescribed strength which is fixed with anchor bolts to the side of a pier below a steel girder; a height adjustment member installed between the underside of the steel girder and the upper flange of the expansion bracket; an overhang bracket which is connected to the side of a main steel plate in the vertical direction which constitutes the steel girder; a connecting steel member which is interposed between the main steel plate of the steel girder and the overhang bracket and connects the overhang bracket to the main steel plate; and a splice plate which connects the overhang bracket to the connecting steel member, the method comprising the steps of: selecting components to be used to construct a temporary support bracket which is to be installed on the pier of a bridge to be constructed and which will temporarily support the load of a steel girder from among a plurality of groups of components which are different in size and strength and which are prepared in advance for each component; The plurality of part groups include at least a part group of an overhang bracket, a connecting reinforcing steel member, and a splice plate, A first step of determining whether or not a girder height of a bridge to be constructed is greater than a predetermined value; A second step of determining whether the temporary support bracket to be installed needs to temporarily support a live load; A third step is to determine whether or not there is a girder drawing of the bridge to be constructed and the drawing number is known; A fourth step of determining whether the bridge to be constructed is a diagonal girder; a fifth step of calculating a temporary support reaction force to be supported by the temporary support bracket using a predetermined reaction force calculation formula when the first step determines that the girder height is greater than a predetermined value, the second step determines that temporary support of a live load is necessary, the third step determines that the drawing number is known, and the fourth step determines that the girder is not an oblique girder; A sixth step of selecting one each of the overhang brackets, connecting reinforcement steel members, and splice plates to be used from the plurality of component groups using a bracket selection sheet that has been created in advance based on the temporary support reaction force calculated in the fifth step and the girder length of the bridge to be constructed; Including, The bracket selection sheet is a two-dimensional pattern diagram which has factors of temporary support reaction force and bridge girder length, a type classification value related to the load of the temporary support reaction force and a type classification value related to the girder length, and which shows the selection area of ​​the target parts on an orthogonal coordinate system with the two factors as the X-coordinate and the Y-coordinate, and at least one corresponding to the overhang bracket is prepared in advance.

2. A method for selecting components of a temporary support bracket as described in claim 1, characterized in that if it is determined in the fourth step that the bridge pier is not an oblique beam, the method further comprises a seventh step of determining whether there is enough space to install a jack on the top surface of the pier of the bridge to be constructed, and if it is determined in the seventh step that there is enough space to install a jack, it is decided not to use an expansion bracket, and if it is determined that there is not enough space to install a jack, it is decided to use an expansion bracket, and then the sixth step is executed.

3. A method for selecting components of a temporary support bracket as described in claim 2, characterized in that a plurality of expansion brackets different in size and strength are prepared as the expansion brackets, and if it is decided in the seventh step to use an expansion bracket, in the sixth step, one expansion bracket to be used is selected from the plurality of expansion brackets based on the temporary support reaction force calculated in the fifth step and the girder length of the bridge to be constructed.

4. A method for selecting components of a temporary support bracket as described in claim 2 or 3, characterized in that in selecting the expansion bracket, when the load received by the temporary support bracket to be selected is greater than a predetermined value or when the girder length of the bridge to be constructed is longer than a predetermined value, it is decided that two expansion brackets of the same type should be fixed side by side to the side of the pier below the steel girder.

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