Main beam adjustment jig and main beam construction method using the same

Abstract

To provide a jig for adjusting steel joists that can be easily and accurately installed on a foundation. [Solution] The main beam adjustment jig 1 is used to adjust the level of a steel main beam 110 installed on a foundation 100 to a horizontal level. It includes a support plate 10 that is placed over the upper surface of the steel main beam 110 temporarily placed on the foundation 100. A magnet 20 is provided on the lower surface of the support plate 10 to fix the steel main beam 110 by magnetic force. The support plate 10 has protrusions 11 formed on both ends of the support plate 10 in a direction perpendicular to the material axis direction of the steel main beam 110, and each protrusion 11 is provided with a feed screw mechanism 30A, 30B that raises and lowers the support plate 10.

Description

Technical Field

[0001] The present invention relates to a stay adjustment tool for horizontally adjusting the level of a steel stay installed on a foundation, and a stay construction method using the same.

Background Art

[0002] In residential construction, when installing a stay on the rising part of a foundation, a fixing fitting (metal fitting) is attached to the foundation, and the stay is fixed to the foundation through this fixing fitting. As such a stay, a steel stay with excellent light weight is often used. Further, when fixing the stay to the foundation, wedges are used from both sides of the stay to adjust the height and the horizontal level of the top edge of the stay.

[0003] However, when constructing a steel stay on a foundation, there were the following problems. Due to the light weight of the steel stay, during the screw driving operation for fixing the steel stay and the fixing fitting, the wedge is likely to move due to vibration or the like, and there was a concern that high-precision construction would be difficult. In particular, it has become difficult to perform the screw driving operation stably in places such as entrances, and the skill level of workers has been required.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The present invention has been made in consideration of the above-described circumstances, and an object thereof is to provide a stay adjustment tool that can easily and accurately perform the construction of a steel stay on a foundation, and a stay construction method using the same.

Means for Solving the Problems

[0006] The present invention provides the following means for solving the above-mentioned problems. Specifically, the present invention is a beam adjustment jig for adjusting the level of a steel beam installed on a foundation to be horizontal, comprising a support plate that is placed over the upper surface of the steel beam temporarily placed on the foundation, a fixing means for fixing the steel beam by magnetic force provided on the lower surface of the support plate, and the support plate having protrusions that project outward from both ends of the support plate in a direction perpendicular to the material axis direction of the steel beam, and each protrusion is provided with a lifting mechanism for raising and lowering the support plate up and down.

[0007] By using the main beam adjustment jig with the above configuration, the steel main beams can be installed on the foundation easily and with high precision. Specifically, when installing the steel main beams on the foundation, fixing the steel main beams to the support plates with the fixing means suppresses displacement of the steel main beams due to vibrations during the screw-driving work to fix the steel main beams to the fixing brackets, enabling highly precise installation. Moreover, since the screw-driving work is performed with the steel main beams fixed to the support plates with the fixing means, there is no need to use wedges or the like, making installation easy and quick. At that time, both of the worker's hands are free, so they can firmly hold the material with both hands while driving screws, enabling stable installation. In the above configuration, it is preferable that the upper surface of the support plate or the upper surface of the protrusion is provided with first and second spirit levels arranged along two mutually orthogonal directions.

[0008] With this configuration, it is easy to check whether the steel beams are level or not by using the first and second spirit levels.

[0009] In the above configuration, each lifting mechanism is a feed screw mechanism, having a screw shaft screwed into a nut member integrally provided on the support plate, and the support plate is raised and lowered by rotating the screw shaft, and it is preferable that the screw shafts of each lifting mechanism are arranged on both sides in a direction perpendicular to the material axis direction with respect to the steel beam.

[0010] With this configuration, for example, by rotating the screw shaft using an impact driver, the height position of the support plate can be quickly adjusted, and even large position adjustments can be made quickly. Therefore, the steel beams can be installed on the foundation quickly. In addition, by providing a wing nut on the screw shaft and rotating the wing nut manually, the height position of the support plate can be finely adjusted, allowing for the precise installation of the steel beams on the foundation.

[0011] In the above configuration, it is preferable that the head of the screw shaft has a recess that can be fitted with a driver, and that a wing nut is integrally provided thereon.

[0012] This configuration allows for adjustment of the support plate's height according to the conditions during the construction of the steel beams. Specifically, when it is necessary to raise or lower the support plate significantly, such as immediately after setting up the beam adjustment jig during the construction of the steel beams, the height of the support plate can be quickly adjusted by, for example, fitting an impact driver into the recess and rotating the screw shaft. Furthermore, when it is necessary to raise or lower the support plate only slightly, such as after adjustment with an impact driver or when readjusting the height of the support plate, the height of the support plate can be finely adjusted by manually rotating the wing nut to rotate the screw shaft.

[0013] Furthermore, the present invention relates to a method for constructing a main beam using the main beam adjustment jig with the above configuration, characterized in that the steel main beam is temporarily placed on the foundation, the main beam adjustment jig is positioned at two locations spaced apart in the axial direction of the steel main beam so as to cover the upper surface of the steel main beam with the support plates, the steel main beam is fixed to the support plates by the fixing means, and the level of the steel main beam is adjusted by raising and lowering the support plates up and down using each lifting mechanism.

[0014] This method of constructing main beams yields the same effects as those achieved with the main beam adjustment jig described above. In other words, by using the main beam adjustment jig described above, steel main beams can be easily and accurately installed on the foundation. [Effects of the Invention]

[0015] The main beam adjustment jig and the main beam construction method using the present invention enable the rapid and accurate construction of steel main beams on the foundation. [Brief explanation of the drawing]

[0016] [Figure 1] This is a perspective view showing the schematic configuration of a beam adjustment jig according to an embodiment of the present invention. [Figure 2] This is a perspective view of the support plate of the main beam adjustment jig, seen from the underside. [Figure 3] This is a cross-sectional view taken along line A1-A1 in Figure 1. [Figure 4] This is a plan view illustrating the general procedure for installing steel beams on a foundation using a beam adjustment jig according to an embodiment of the present invention. [Figure 5] This is also a cross-sectional view showing an outline of the construction procedure, specifically the A2-A2 cross-section in Figure 4. [Figure 6] This is a cross-sectional view showing an overview of the construction procedure. [Figure 7] This is a cross-sectional view showing an overview of the construction procedure. [Figure 8] This is a cross-sectional view showing an overview of the construction procedure. [Figure 9] It is a cross-sectional view showing an outline of the construction procedure as well.

Embodiments for Carrying Out the Invention

[0017] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0018] As shown in FIGS. 1 to 9, the large draw adjusting jig 1 according to this embodiment is a jig for horizontally adjusting the level of the steel large draw 110 installed on the foundation 100. It includes a support plate 10 that is placed on the upper surface side of the steel large draw 110 temporarily placed on the foundation 100. On the lower surface of the support plate 10, fixing means for fixing the steel large draw 110 by magnetic force is provided. On the support plate 10, protruding portions 11 that protrude outward from both ends in the direction orthogonal to the material axis direction of the steel large draw 110 of the support plate 10 are respectively formed. On each protruding portion 11, a lifting mechanism for lifting and lowering the support plate 10 is respectively provided. For the sake of convenience, as shown in FIGS. 1 to 3, the three axial directions orthogonal to each other will be described as the vertical direction (the vertical direction in FIGS. 1 to 3), the front-rear direction, and the left-right direction. The left-right direction is the material axis direction (longitudinal direction) of the steel large draw 110, and the front-rear direction is the direction orthogonal to the material axis direction of the steel large draw 110.

[0019] The specific configuration of the large draw adjusting jig 1 will be described with reference to FIGS. 1 to 3. The large draw adjusting jig 1 includes a support plate 10 formed in a flat plate shape. On the support plate 10, a protruding portion 11 and a vertical piece 12 are integrally provided. The support plate 10, the protruding portion 11, and the vertical piece 12 are formed, for example, by punching a substantially rectangular steel plate by pressing and then bending the punched plate.

[0020] The support plate 10 is a roughly rectangular portion that is placed over the upper surface of the steel beam 110. The width W1 of the support plate 10 in the front-rear direction is formed to be approximately the same as the width of the steel beam 110 that is to be constructed in the direction perpendicular to the material axis direction. The upper surface of the support plate 10 is provided parallel to the upper surface of the steel beam 110, which is fixed to the lower surface of the support plate 10 by the magnetic force of the magnet 20. In the left-right central part of the support plate 10, a pair of protrusions 11 are formed that protrude outward from both ends of the support plate 10 in the front-rear direction. The upper surfaces of the protrusions 11 are provided on the same plane as the upper surface of the support plate 10.

[0021] Vertical pieces 12 extending downward are integrally formed at both ends of the support plate 10 in the left-right direction. The vertical pieces 12 are formed by bending portions extending outward from both ends of the support plate 10 in the front-rear direction at approximately vertical angles. Two vertical pieces 12 are provided at each end of the support plate 10 in the left-right direction. The vertical pieces 12 are positioned along the side surface of the steel beam 110 in the front-rear direction, thereby restricting the front-rear movement of the steel beam 110.

[0022] Multiple circular magnets 20 (three in Figure 2) are provided on the underside of the support plate 10 as fixing means for securing the steel beam 110. The magnets 20 are fixed to the underside of the support plate 10 by means of adhesive tape, for example. By fixing the steel beam 110 to the underside of the support plate 10 with the magnetic force of the magnets 20, the position of the steel beam 110 in the front-to-back and left-to-right directions is fixed, preventing the steel beam 110 from shifting position.

[0023] Each protrusion 11 is provided with a feed screw mechanism 30A, 30B, which serves as a lifting mechanism for raising and lowering the support plate 10. The feed screw mechanisms 30A and 30B have the same configuration. The feed screw mechanism 30A is provided on the protrusion 11 located on the front end side of the support plate 10. The feed screw mechanism 30A is configured to raise and lower the front end portion of the support plate 10 by rotating the screw shaft 31 in forward and reverse directions. The feed screw mechanism 30B is provided on the protrusion 11 located on the rear end side of the support plate 10. The feed screw mechanism 30B is configured to raise and lower the rear end portion of the support plate 10 by rotating the screw shaft 31 in forward and reverse directions.

[0024] The feed screw mechanisms 30A and 30B have a wing nut 32 integrally attached to the head of the screw shaft 31, and by manually rotating the wing nut 32, the screw shaft 31 rotates in the same direction. In addition, a Phillips head recess (cross hole) 33 is formed on the head of the screw shaft 31, making it possible to rotate the screw shaft 31 using a Phillips screwdriver. The screw shaft 31 is inserted through a through hole 13 formed in the protruding portion 11, and the lower end of the screw shaft 31 protrudes below the support plate 10. The screw shaft 31 is screwed into a nut 34 fixed to the lower surface of the protruding portion 11 by welding or the like. A leg portion 35 is integrally provided at the lower end of the screw shaft 31 so as to be able to contact the upper surface of the foundation 100 when the steel beam 110 is installed on the foundation 100. When the screw shaft 31 is rotated, the leg portion 35 rotates together with the screw shaft 31, but the nut 34 screwed onto the middle portion of the screw shaft 31 does not rotate, so the nut 34 moves up and down along the screw shaft 31. Consequently, the protruding portion 11 to which the nut 34 is fixed moves up and down, and the front or rear end of the support plate 10 also moves up and down.

[0025] The upper surface of the support plate 10 is provided with first and second spirit levels 40A and 40B, which are arranged along two mutually orthogonal directions. In this embodiment, the first spirit level 40A is arranged along the front-to-back direction, and the second spirit level 40B is arranged along the left-to-right direction. The first and second spirit levels 40A and 40B may be fixed to the upper surface of the support plate 10, or they may be provided on the upper surface of the support plate 10 in a manner that allows them to be detached.

[0026] Next, the procedure for constructing steel beams 110 on the foundation 100 using the beam adjustment jig 1 with the above configuration will be explained with reference to Figures 4 to 9.

[0027] First, as shown in Figures 4 and 5, the steel beam 110 is temporarily placed on the foundation 100, and the beam adjustment jig 1 is positioned at two locations spaced apart in the material axis direction of the steel beam 110, with the support plate 10 covering the upper surface of the steel beam 110. Then, the steel beam 110 is fixed to the support plate 10 by magnets 20. For example, the beam adjustment jig 1 is positioned at two locations near both ends in the material axis direction of the temporarily placed steel beam 110. In this case, fixing brackets (metal fittings) 120 are attached to predetermined positions on the foundation 100 in advance, and the steel beam 110 is temporarily placed on the fixing brackets 120. In this case, it is preferable to position the beam adjustment jig 1 closer to the center in the material axis direction than the fixing brackets 120 attached near both ends in the material axis direction of the steel beam 110. If the leg portion 35 is not in contact with the upper surface of the foundation 100, or if there is a gap between the magnet 20 and the steel beam 110, the height of the support plate 10 can be adjusted by rotating the wing nut 32 to bring the leg portion 35 into contact with the upper surface of the foundation 100 or to fix the steel beam 110 to the magnet 20.

[0028] Next, as shown in Figures 6 and 7, the screw shafts 31 of the feed screw mechanisms 30A and 30B of the beam adjustment jig 1, which are located at one end of the steel beam 110 in the material axis direction (for example, the left end in Figure 4), are rotated to adjust the inclination of the steel beam 110 in the direction perpendicular to the material axis direction (front-back direction). In addition, the screw shafts 31 of the feed screw mechanisms 30A and 30B of the beam adjustment jig 1, which are located at the other end of the steel beam 110 in the material axis direction (for example, the right end in Figure 4), are rotated to adjust the inclination of the steel beam 110 in the direction perpendicular to the material axis direction (front-back direction) and the inclination of the steel beam 110 in the material axis direction (left-right direction).

[0029] Specifically, as shown in Figure 6, with the steel beam 110 fixed to the support plate 10 by the magnet 20, the height of the support plate 10 is adjusted by raising and lowering the support plate 10 by rotating the screw shaft 31 of the beam adjustment jig 1 using an impact driver 130. Alternatively, as shown in Figure 7, the height of the support plate 10 is adjusted by manually rotating the screw shaft 31 by rotating the wing nut 32 fixed to the screw shaft 31 of the beam adjustment jig 1, thereby raising and lowering the support plate 10. At this time, while checking the first spirit level 40A provided on the upper surface of the support plate 10, the level is adjusted so that the upper surface of the steel beam 110 is horizontal along the direction perpendicular to the material axis (front-to-back direction). Also, while checking the second spirit level 40B provided on the upper surface of the support plate 10, the level is adjusted so that the upper surface of the steel beam 110 is horizontal along the material axis (left-to-right direction).

[0030] Then, as shown in Figure 8, the steel beam 110 is fixed to the fixing bracket 120 by driving screws using an impact driver 130, thereby fixing the steel beam 110 on the foundation 100. At this time, the position of the steel beam 110 is fixed by the magnetic force of the magnet 20, so it is possible to perform the screw driving work stably. Alternatively, the level adjustment may be performed at both ends of the steel beam 110 in the direction of the material axis, and then the screw driving may be performed at both ends of the steel beam 110 in the direction of the material axis. Or, the level adjustment may be performed at one end of the steel beam 110 in the direction of the material axis (for example, the left end in Figure 4), then the screw driving may be performed at the other end of the steel beam 110 in the direction of the material axis, and then the level adjustment may be performed at the other end of the steel beam 110 in the direction of the material axis (for example, the right end in Figure 4), and then the screw driving may be performed at the other end of the steel beam 110 in the direction of the material axis. Alternatively, the steel beam 110 may be leveled at both ends in the axial direction, screwed in on one end (for example, the lower side in Figure 4), then leveled again, and screwed in on the other end (for example, the upper side in Figure 4).

[0031] Next, as shown in Figure 9, the main beam adjustment jig 1 is lifted upward, separating the steel main beam 110 from the support plate 10, and the main beam adjustment jig 1 is removed to complete the construction work. At this time, since the steel main beam 110 is fixed on the foundation 100 by the fixing bracket 120, the main beam adjustment jig 1 can be easily removed.

[0032] In this embodiment, the main beam adjustment jig 1 includes a support plate 10 that is placed over the upper surface of a steel main beam 110 temporarily placed on the foundation 100. A magnet 20 is provided on the lower surface of the support plate 10 to fix the steel main beam 110 by magnetic force. The support plate 10 has protrusions 11 that protrude outward from both ends of the support plate 10 in a direction perpendicular to the material axis direction of the steel main beam 110, and each protrusion 11 is provided with a feed screw mechanism 30A, 30B that raises and lowers the support plate 10.

[0033] By using the main beam adjustment jig 1 with the above configuration, the steel main beam 110 can be installed on the foundation 100 easily and with high precision. Specifically, when installing the steel main beam 110 on the foundation 100, fixing the steel main beam 110 to the support plate 10 with the magnet 20 suppresses displacement of the steel main beam 110 due to vibrations during the screw-driving work to fix the steel main beam 110 to the fixing bracket 120, enabling highly accurate installation. Moreover, by performing the screw-driving work with the steel main beam 110 fixed to the support plate 10 by the magnet 20, the need to use wedges or the like is eliminated, making installation easy and quick. At that time, both of the worker's hands are free, so they can firmly hold the material with both hands while driving screws, enabling stable installation.

[0034] In this embodiment, the upper surface of the support plate 10 is provided with first and second spirit levels 40A and 40B arranged along two mutually orthogonal directions. Therefore, it is easy to check whether the steel beam 110 is level or not by using the first and second spirit levels 40A and 40B.

[0035] In this embodiment, the feed screw mechanisms 30A and 30B each have a screw shaft 31 screwed into a nut 34 integrally provided on the support plate 10, and the support plate 10 is raised and lowered by rotating the screw shaft 31. The screw shafts 31 of the feed screw mechanisms 30A and 30B are positioned on both sides of the steel beam 110 in a direction perpendicular to the material axis direction. This allows the height position of the support plate 10 to be quickly adjusted by rotating the screw shaft 31, for example, using an impact driver 130, and large position adjustments can also be made quickly. Therefore, the steel beam 110 can be installed on the foundation 100 quickly. In addition, a wing nut 32 is provided on the screw shaft 31, and the height position of the support plate 10 can be finely adjusted by manually rotating the wing nut 32, allowing for accurate installation of the steel beam 110 on the foundation 100.

[0036] Each of the feed screw mechanisms 30A and 30B has a recess 33 formed on the head of the screw shaft 31 that can be fitted with a driver, and a wing nut 32 is integrally provided. This makes it possible to adjust the height position of the support plate 10 according to the conditions during the construction of the steel beam 110. Specifically, when it is necessary to raise or lower the support plate 10 significantly, such as immediately after setting the beam adjustment jig 1 during the construction of the steel beam 110 (see Figures 4 and 5), the height position of the support plate 10 can be quickly adjusted by fitting an impact driver 130 into the recess 33 and rotating the screw shaft 31. Also, when it is necessary to raise or lower the support plate 10 only slightly, such as after adjustment with the impact driver 130 (see Figure 6) or when it is necessary to readjust the height position of the support plate 10, the height position of the support plate 10 can be finely adjusted by manually rotating the wing nut 32 and then rotating the screw shaft 31.

[0037] Furthermore, in the main beam construction method described above, the steel main beam 110 is temporarily placed on the foundation 100, and the main beam adjustment jig 1 is positioned at two locations spaced apart in the axial direction of the steel main beam 110, with the support plates 10 placed over the upper surface of the steel main beam 110. With the steel main beam 110 fixed to the support plates 10 by magnets 20, the level of the steel main beam 110 is adjusted by raising and lowering the support plates 10 using feed screw mechanisms 30A and 30B. With this main beam construction method, the same effects as those of the main beam adjustment jig 1 described above can be obtained. In other words, by using the main beam adjustment jig 1, the steel main beam 110 can be constructed on the foundation 100 easily and with high precision.

[0038] The present invention can be implemented in various other forms without departing from its spirit, purpose, or main features. Therefore, the embodiments described above are merely illustrative in all respects and should not be constrained. The scope of the invention is defined by the claims, and the text of the specification is not restrictive. Furthermore, any modifications or changes within the equivalent scope of the claims are all within the scope of the invention.

[0039] In the above embodiment, a circular magnet 20 was used as the fixing means, but the fixing means is not particularly limited as long as it has magnetic force capable of fixing the steel beam 110 to the lower surface of the support plate 10. For example, permanent magnets such as ferrite magnets, neodymium magnets, and samarium-cobalt magnets can be used as the magnet 20, or electromagnets can be used. Furthermore, the number, shape, and size of the magnets 20 are not particularly limited. Also, the method of fixing the magnets 20 to the support plate 10 is not particularly limited, and for example, the magnets 20 may be fixed using adhesive.

[0040] In the above embodiment, feed screw mechanisms 30A and 30B were used as the lifting mechanism, but the system is not limited to these, and other mechanisms may be used. For example, a ball screw mechanism may be used as the lifting mechanism. Also, in the above embodiment, the support plate 10 was raised and lowered by an impact driver 130, but the system is not limited to this, and the operator may raise and lower the support plate 10 using a screwdriver. Also, in the above embodiment, the screw shaft 31 was screwed into a nut 34 integrally provided on the protrusion 11 of the support plate 10, but the system is not limited to this, and a screw groove may be formed in the through hole 13 of the protrusion 11, and the screw shaft 31 may be screwed into this screw groove, in which case the nut 34 can be omitted.

[0041] In the above embodiment, the second spirit level 40B is placed on the upper surface of the support plate 10, but the invention is not limited to this, and the second spirit level 40B may be placed on the upper surface of the protrusion 11. Alternatively, the second spirit level 40B may be placed so as to straddle the upper surface of both the support plate 10 and the protrusion 11. Furthermore, the first and second spirit levels 40A and 40B may not be placed on the upper surface of the support plate 10 before and after using the beam adjustment jig 1, and the first and second spirit levels 40A and 40B may only be placed on the upper surface of the support plate 10 when performing level adjustment using the beam adjustment jig 1.

[0042] (Note 1) A jig for adjusting the level of steel beams installed on a foundation to make them horizontal, The system includes a support plate that is placed over the upper surface of the steel beam temporarily placed on the foundation, The lower surface of the support plate is provided with fixing means for fixing the steel beam by magnetic force. The support plate has protrusions formed on both ends of the support plate in a direction perpendicular to the axial direction of the steel beam, which protrude outward. A beam adjustment jig characterized in that each protruding portion is provided with a lifting mechanism for raising and lowering the support plate.

[0043] (Note 2) In the main beam adjustment jig described in Appendix 1, A beam adjustment jig characterized in that a first and second spirit level are provided on the upper surface of the support plate or the upper surface of the protrusion, arranged along two mutually orthogonal directions.

[0044] (Note 3) In the main beam adjustment jig described in Appendix 1 or 2, Each lifting mechanism is a feed screw mechanism, having a screw shaft screwed into a nut member integrally provided on the support plate, and is configured to raise and lower the support plate by rotating the screw shaft. A beam adjustment jig characterized in that the screw shafts of each lifting mechanism are arranged on both sides of the steel beam in a direction perpendicular to the material axis direction.

[0045] (Note 4) In the main beam adjustment jig described in Appendix 3, A beam adjustment jig characterized in that the head of the screw shaft has a recess formed therein that can be fitted with a screwdriver, and a wing nut is integrally provided thereon.

[0046] (Note 5) A method for constructing a main beam using a main beam adjustment jig described in any one of the appendices 1 to 4, The steel beams are temporarily placed on the aforementioned foundation, At two locations spaced apart in the axial direction of the steel beam, the beam adjustment jig is positioned such that the support plate is placed over the upper surface of the steel beam. A method for constructing a main beam, characterized in that the main steel beam is fixed to the support plate by the fixing means, and the level of the main steel beam is adjusted by raising and lowering the support plate up and down using each lifting mechanism. [Explanation of Symbols]

[0047] 1. Main beam adjustment jig 10 Support plate 11 Protrusion 20 Magnets (fixing means) 30A, 30B Feed screw mechanism (lifting mechanism) 31 Screw shaft 32 Wing nuts 40A, 40B First and second spirit levels 100 Basics 110 Steel drawer

Claims

1. A jig for adjusting the level of steel beams installed on a foundation to make them horizontal, The system includes a support plate that is placed over the upper surface of the steel beam temporarily placed on the foundation, The lower surface of the support plate is provided with fixing means for fixing the steel beam by magnetic force. The support plate has protrusions formed on both ends of the support plate in a direction perpendicular to the axial direction of the steel beam, which protrude outward. A beam adjustment jig characterized in that each protruding portion is provided with a lifting mechanism for raising and lowering the support plate.

2. In the main beam adjustment jig according to claim 1, A beam adjustment jig characterized in that a first and second spirit level are provided on the upper surface of the support plate or the upper surface of the protrusion, arranged along two mutually orthogonal directions.

3. In the main beam adjustment jig according to claim 1, Each lifting mechanism is a feed screw mechanism, having a screw shaft screwed into a nut member integrally provided on the support plate, and is configured to raise and lower the support plate by rotating the screw shaft. A beam adjustment jig characterized in that the screw shafts of each lifting mechanism are arranged on both sides of the steel beam in a direction perpendicular to the material axis direction.

4. In the main beam adjustment jig according to claim 3, A beam adjustment jig characterized in that the head of the screw shaft has a recess formed therein that can be fitted with a screwdriver, and a wing nut is integrally provided thereon.

5. A method for constructing a main beam using the main beam adjustment jig described in any one of claims 1 to 4, The steel beams are temporarily placed on the aforementioned foundation, At two locations spaced apart in the axial direction of the steel beam, the beam adjustment jig is positioned such that the support plate is placed over the upper surface of the steel beam. A method for constructing a main beam, characterized in that the main steel beam is fixed to the support plate by the fixing means, and the level of the main steel beam is adjusted by raising and lowering the support plate up and down using each lifting mechanism.

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