Truss beam support column structure

Abstract

To provide a simple and inexpensive support column structure of a truss beam which can reduce thrusts generated in a column base part of a support column as much as possible, even if a support column length of the truss beam is short, in a roof frame composed of the truss beam.SOLUTION: A support column 3 and a truss beam 2 are connected to each other by only an upper chord part of the truss beam 2, in a case in which a flexible part 3a is provided on only a column head of the support column 3, when the truss beam 2 is bent and the support column 3 is inclined inward, the flexible part 3a composed of a flexible plate whose plate thickness direction coincides with a span direction of the truss beam 2 is also inclined and rotated, and accordingly little bending moment is generated in the column head of the support column 3, which can greatly reduce thrusts generated in a column base part of the support column 3.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a support column structure of steel columns that support truss beams, which are used in the roof frame of a large-beam building such as an arena building. [Background technology]

[0002] In the past, truss beams were often used in roof structures spanning large beams, such as those found in indoor sports facilities such as arenas. When the gable ends and girder faces of the roof structure made of truss beams were supported by support columns, vertical braces were sometimes installed within the structural surface (wall surface) that included the eaves beams of the roof structure and the support columns, creating a structural form that could resist seismic forces in the span and girder directions (see Figure 1).

[0003] As shown in Figure 1, in the case of a roof frame 1 consisting of truss beams 2, 2, ... and roof braces V2, V2, ..., in which support columns 3, 3, ... for the truss beams 2, 2, ... and vertical braces V1, V1, ... are installed on the wall surfaces in both the span and girder directions (hereinafter referred to as a bidirectional braced frame), for example, the horizontal seismic force acting in the span direction of the roof frame 1 can be transmitted via the roof braces V2, V2, ... to the vertical braces V1, V1, ... on both end faces, so the frame in the span direction does not necessarily have to be a rigid frame structure.

[0004] On the other hand, if the frame in the span direction is a rigid frame structure, a thrust (a force that causes the column bases to expand outward) occurs at the column bases of the support columns 3, 3, ... that support the truss beams 2, 2, ... when a vertical load is applied, as shown by the arrows in Figure 2. Therefore, for the lower body columns 4, 4 that support the column bases of the support columns 3, 3 in the span direction, it is necessary to design the members taking into account the bending moment and shear force caused by this thrust.

[0005] Furthermore, when the truss beam 2 in the span direction of the rigid frame structure is deflected by a vertical load (as shown by the dashed line in Figure 2), the column heads P1, P1 of the support columns 3, 3 that connect with the lower chord of the truss beam 2 are displaced outward, and the upper chord nodes P2, P2 of the truss beam 2 directly above the column heads of the support columns 3, 3 are displaced inward, so that, particularly when the height of the support columns 3, 3 that support the truss beam 2 is low, the thrust in the direction of the arrow shown in Figure 2 becomes larger. In other words, this leads to a larger horizontal force (thrust) being applied to the lower frame columns 4, 4, ...

[0006] For the above reasons, in the case of a two-way braced frame consisting of a truss beam with supporting columns 3, 3, it is preferable not to use a rigid frame structure for the span direction frame, as this reduces the burden on the lower body columns 4, 4, .... Also, in the case of a truss beam 2 with supporting columns 3, 3 spanning the girder direction, it is preferable not to use a rigid frame structure for the same reason.

[0007] One way to reduce the thrust of the legs of the support columns 3, 3 as described above is, for example, to omit the lower chord members at the ends of the truss beam 2 that are connected to the support columns 3, 3, and connect the column heads of the support columns 3, 3 only to the upper chord nodes P2, P2 of the truss beam 2, as shown in Figure 3.

[0008] In other words, even if the column heads of the support columns 3, 3 and the upper chord part of the truss beam 2 (upper chord nodes P2, P2) are rigidly connected, the column length can be secured, and the bending rigidity of the support columns 3, 3 is reduced, so the thrust becomes smaller.

[0009] However, even if the lower chord of the truss beam 2 connected to the support columns 3, 3 is omitted as shown in Figure 3, if the length of the support columns 3, 3 is short, for example, approximately the same length as the height of the truss beam 2, as shown in Figure 4(a), the bending rigidity will be high if the column heads of the support columns 3, 3 and the upper chord of the truss beam 2 (upper chord nodes P2, P2) are rigidly connected.

[0010] Furthermore, the anchor bolts 5, 5, ... (see Figure 5) that secure the bases of the support columns 3, 3 have a certain bending resistance, which increases the bending rigidity of the support columns 3, 3. Therefore, if the length of the support columns 3, 3 is short, it is difficult to obtain a sufficient thrust reduction effect.

[0011] When the length of the support columns 3, 3 is short as described above, the following method can be considered to reduce the rotational rigidity of the upper or lower ends of the support columns 3, 3 in order to reduce the thrust. Figures 4(b) and (c) are enlarged views of part A in Figure 4(a), with Figure 4(b) being a case where only the column capital is pin-jointed (indicated by ●), and Figure 4(c) being a schematic diagram where the column capital and base are pin-jointed (indicated by ●). In particular, in the case of Figure 4(c), since both the upper and lower ends of the column are pin-jointed, no bending moment acts on the support columns 3, 3, and only axial force (vertical force) is transmitted to the lower body columns 4, 4, ..., so the thrust does not occur.

[0012] The ideal pin joint structure as described above would be a single-pin joint like a clevis joint, but when a vertical brace is attached to the column head or base, the fit becomes more complicated. In addition, this is more expensive than the fit of a typical steel column joint. Therefore, a simple structure that can be considered a pin joint was needed for the support columns of truss beams.

[0013] Prior art relating to the joint structure between a truss beam and the column head or column base of a column supporting the truss beam includes, for example, the invention described in Patent Document 1.

[0014] The invention described in Patent Document 1 discloses a sliding construction method for a portal frame structure, in which the joint between the top of the columns of the portal frame partial frame and the roof section is made by connecting only either the upper or lower chord at both ends of the roof girder (truss beam), leaving the joint in a state (pin joint) that allows a certain degree of rotation in the vertical plane at both ends of the roof section, and while both ends of the roof girder are left in the pin joint state, the jacks of the jack-equipped shoring that supports the roof section of the portal frame partial frame are loosened to release the temporary support of the roof section by the shoring, and then the unconnected parts (lower chord or upper chord) at both ends of the roof girder are connected to the columns, thereby rigidly joining the top of the columns of the portal frame partial frame and the roof section and completing the portal frame structure.

[0015] Therefore, while both ends of the roof girder remain in a pin-jointed state, the temporary support provided by the shoring supporting the roof of the portal-shaped partial frame is released, and then the unconnected parts (lower chord or upper chord) at both ends of the roof girder are connected to the columns, rigidly connecting the top of the columns and the roof, so that no bending moment due to the vertical load of the roof is generated in the columns of the portal-shaped partial frame; in other words, no thrust is generated in the column bases of the portal-shaped partial frame.

[0016] However, the invention described in Patent Document 1 does not explicitly state or suggest the specific fit (structure) of the pin joint portions at both ends of the roof girder. [Prior art documents] [Patent documents]

[0017] [Patent Document 1] Patent No. 6636091 Summary of the Invention [Problem to be solved by the invention]

[0018] The present invention provides a simple and inexpensive truss beam support column structure that can minimize the thrust generated at the base of the support column due to the vertical load of the roof portion in a roof frame consisting of truss beams, even when the support column length of the truss beam is short. [Means for solving the problem]

[0019] The means of the present invention to solve the above problem is a support column structure for a truss beam, characterized in that in a roof frame consisting of a truss beam, a flexible section made of a flexible plate whose thickness direction coincides with the span direction of the truss beam is formed at the column head or column base of the support column supporting the truss beam, and the flexible section is formed to a predetermined length in the material axis direction of the support column.

[0020] The present invention also provides A flexible section made of a flexible plate whose thickness direction coincides with the span direction of the truss beam is formed at the column head or column base of the support column supporting the truss beam, with a predetermined length in the material axis direction of the support column; The flexible portion formed at the column head or column base of the support column that supports the truss beam of , consisting of one or more flexible plates death and a deformation suppressing portion that suppresses deformation of the flexible plate. of The flexible plate is provided on one or both sides. hair , a gap dimension between the flexible plate and the deformation suppression portion of , The vertical or horizontal load on the roof structure The support pillar is assumed R Set according to the amount of tilt or rotation of the truss beam end do The truss beam support column structure is characterized by the Design method is.

[0021] The present invention also provides a support column structure for a truss beam, characterized in that the support column of the truss beam has the flexible portion at the column head or column base when the support column is short, for example, approximately the same as the truss beam depth, and the connection between the support column and the truss beam is only at the upper chord portion of the truss beam.

[0022] The flexible plate described above must have a thickness and width sufficient to support the axial force of the support column and a length that will not buckle, but since the equivalent moment of inertia of the flexible section is significantly smaller than the moment of inertia of the support column shaft, the rotational rigidity of the flexible section when bent is small, and it can be designed to be regarded as a pin joint in practice. The rotational rigidity of the flexible section can be calculated from the cross-sectional dimensions and length (height) of the flexible plate.

[0023] Therefore, even if the support columns of the truss beam are short, when the truss beam bends due to a vertical load such as its own weight, the flexible plates of the flexible parts formed at the head or base of the support column support the axial force of the support column transmitted from the truss beam, and at the same time, they bend in response to the tilt of the support column or the rotation of the end of the truss beam, and the flexible parts rotate just like a pin joint, allowing the support column to tilt, thereby significantly reducing the bending moment generated in the support column. Therefore, the thrust generated at the base of the support column is extremely small. [Effects of the Invention]

[0024] The present invention, which is based on the above means, has the following effects. (1) When a truss beam is deflected by a vertical load, if the connection between the support column supporting the truss beam and the truss beam is rigid, a large thrust will be generated in the leg of the support column. However, according to the present invention, this is significantly reduced by the rotation of the flexible part formed in the support column. (2) Furthermore, according to the present invention, even if the support column is short, for example, to the length of the truss beam, by connecting the support column to the truss beam only at the upper chord of the truss beam, the rotation of the flexible part can reduce the thrust of the support column base to a level that is almost negligible. (3) The thrust on the lower structural columns that support the roof structure is significantly reduced, reducing the load on the lower structural columns in the span direction. (4) From the above, the flexible portion, which can be regarded as a pin joint in practice, provides a simple and inexpensive support column structure for the truss beam and also contributes to suppressing the cost increase of the lower structural column. [Brief explanation of the drawings]

[0025] [Figure 1] This is an example of a roof structure made of truss beams, with support columns and vertical braces installed on both the span and girder wall surfaces. (a) is the plan, (b) is the I-I cross section of (a), (c) is the R-R cross section of (a), and (d) is the H-H cross section of (a). [Figure 2] This is an example of a truss beam with support columns in a rigid frame structure, and the dashed line shows the state where deflection occurs due to vertical load. [Figure 3] This is an example of the truss beam with support columns in Figure 2, where the lower chord at the end of the truss beam that connects to the support column is omitted, and the dashed line shows the state in which the truss beam is deflected by a vertical load. [Figure 4] This is an example of a truss beam with support columns in Figure 3, where the support columns are as short as the truss beam depth. (a) is a diagram showing, with broken lines, the state in which the truss beam has deflected due to a vertical load. (b) is an enlarged view of part A in (a), showing the state in which only the column head of the support column is pin-jointed, and (c) is a schematic diagram showing the state in which the column head and column base of the support column are pin-jointed. [Figure 5] This is a first embodiment of the present invention, showing a case where a flexible portion is provided only at the column head of the support column of the truss beam. [Figure 6] This is a second embodiment of the present invention, showing a case where flexible portions are provided at the column head and column base of the support column of the truss beam. [Figure 7] 6A and 6B are detailed views illustrating the flexible portion of the support column of the truss beam, where (a) is an enlarged view of part B in FIGS. 5 and 6A, (b) is an enlarged view of part C in FIG. 6, and (c) is a view showing the state in which the flexible portion of part B has rotated. [Figure 8] This is an example of the second embodiment in which a vertical brace is joined to the base of a support column of a truss beam, and is a cross-sectional view taken along line 2-2 in FIG. 7(b). [Figure 9]This is a third embodiment of the present invention, in which (a) shows a case where flexible sections are provided at the column head and column base of the support column of a truss beam, (b) shows a state in which the flexible section 3a of the column head is inclined, and (c) is an example of a case in which a vertical brace is joined to the column base of the support column of a truss beam. [Figure 10] The flexible part of the support column head of the truss beam of the present invention is located at a position other than the upper chord, where (a) shows a truss beam with support columns when it is located at the lower chord, and (b) shows a truss beam with support columns when it is located at the middle of the truss beam depth (the lattice material attachment part) (corresponding to Figure 1(d)). [Figure 11] This is an example of calculating the end rotation angle θ of a simply supported truss beam. DETAILED DESCRIPTION OF THE INVENTION

[0026] A first embodiment of the present invention is shown in Figure 5. Figure 5 shows a case in which the support column 3 of the truss beam 2 and the truss beam 2 are connected only at the upper chord of the truss beam 2, and flexible portions 3a are provided only at the column heads of the support columns 3. In this embodiment, when the truss beam 2 is deflected by a vertical load, causing the end of the truss beam 2 to rotate and the support columns 3 to tilt inward (see Figure 4(b)), the flexible portions 3a at the column heads of the support columns 3 also tilt and rotate as shown in Figure 7(c) (see Figure 7(c)), and therefore the bending moment generated at the column heads of the support columns 3 is quite small.

[0027] However, when the base plate of the support column 3 is fixed to the lower structural column 4 with multiple anchor bolts 5, 5, ... or when it is rigidly connected to the steel lower structural column (not shown), it is able to resist bending to a certain extent. Therefore, when horizontal loads such as those caused by an earthquake act on the roof in addition to vertical loads, the tilt of the support column 3 causes bending moments and shear forces to act on the lower structural column 4 in addition to axial force.

[0028] Figure 6 shows a second embodiment of the present invention, in which flexible portions 3a are provided at the column head and column base of the support column 3. If flexible portions 3a are also provided at the column base, when the truss beam 2 bends, the end of the truss beam 2 rotates, and the support column 3 tilts, the flexible portions 3a at the column head and column base can rotate together. Therefore, the bending resistance of the anchor bolts 5, 5, ... is reduced, and the bending moment acting on the lower frame column 4 is smaller than in the first embodiment.

[0029] Figure 7 is a detailed view of the flexible section 3a, with Figure 7(a) showing the flexible section 3a installed at the head of the support column 3 and Figure 7(b) showing the flexible section 3a installed at the base of the support column 3. The support column 3 uses an H-shaped cross section member, and no web is installed in a certain range (flexible section 3a) at the end of this member, but instead a single flexible plate 3b is attached in line with the axis of the H-shaped cross section member. In addition, the flange portion of the flexible section 3a in the range where no web is installed is also used as the flexible plates 3b, 3b.

[0030] Deformation suppression portions 3c, 3c are provided in the range of the flexible portion 3a where no web is provided, and vertical slits are set between the flexible plates 3b, 3b, ... and the deformation suppression portions 3c, 3c with gap dimensions that correspond to the expected amount of tilt of the support column 3 and the amount of rotation θ of the end of the truss beam 2. In addition, horizontal slits are also provided between the tips (upper or lower ends) of the deformation suppression portions 3c, 3c and the web toe stiffening plates 3f, 3f of the support column 3, such that the tips of the deformation suppression portions 3c, 3c do not come into contact with the web toe stiffening plates 3f, 3f.

[0031] In the second embodiment, when the vertical brace V1 is attached to the base of the support column 3, as shown in FIG. 8, it is desirable that the gusset plate 3d of the vertical brace V1 be attached to the extension of the flexible plate 3b at the axis of the support column 3, avoiding the flexible portion 3a, in order not to restrict the bending deformation of the flexible plate 3b.

[0032] Since the flexible section 3a according to the first and second embodiments of the present invention is configured as described above, the column head of the support column 3 will be described. As shown in FIG. 7(c), when the support column 3 tilts and the end of the truss beam 2 rotates, the flexible plates 3b also tilt (strictly speaking, gently curve), causing the flexible section 3a to rotate θ. The gap dimensions between the flexible plates 3b and the deformation suppressing sections 3c are set according to the expected tilt amount of the support column 3 and the expected rotation amount of the end of the truss beam 2. Therefore, when the tilt amount of the flexible plates 3b reaches a set value, they come into contact with the deformation suppressing sections 3c, thereby suppressing further tilt of the flexible plates 3b. If the tilt amount of the flexible plates 3b becomes too large, the flexible plates 3b may buckle due to eccentric compression. Therefore, the gaps between the flexible plates and the deformation suppressing sections 3c must be kept to a minimum.

[0033] Figure 9 shows a third embodiment of the present invention. Figure 9(a) shows a case where flexible portions 3a are provided at the column head and column base of a support column 3 of a truss beam 2, Figure 9(b) shows a state where the flexible portion 3a at the column head is inclined, and Figure 9(c) shows a state where a vertical brace V1 is joined to the column base of the support column 3. Note that in the third embodiment, the flexible portion 3a may be provided only at the column head of the support column 3, as in the first embodiment shown in Figure 5.

[0034] In the third embodiment, there is only one flexible plate 3b aligned with the axis of the support column 3, and deformation suppression portions 3c, 3c are provided on both sides of the flexible plate 3b. The vertical slit between the flexible plate 3b and the deformation suppression portions 3c, 3c has a dimension that widens according to the inclination allowed for the flexible plate 3b within the range of the flexible portion 3a.

[0035] In addition, the horizontal slits provided between the tip plates 3e, 3e at the tips (upper or lower ends) of the deformation suppression sections 3c, 3c and the web toe stiffening plates 3f, 3f of the support column 3 also have the same shape and dimensions as the vertical slits toward the outside (the flange side of the support column 3) so that the inclination of the flexible plate 3b is not restricted.

[0036] In the third embodiment, when a vertical brace V1 is attached to the base of the support column 3, as shown in Figure 9(c), it is desirable that the gusset plate 3d of the vertical brace V1 be attached to the extension of the flexible plate 3b, avoiding the flexible portion 3a, so as not to restrict the bending deformation of the flexible plate 3b.

[0037] Since the flexible portion 3a according to the third embodiment of the present invention is configured as described above, when the support column 3 tilts and the end of the truss beam 2 rotates, as shown in Figure 9(b), the flexible plate 3b also tilts (strictly speaking, it curves gently), and the flexible portion 3a rotates θ.

[0038] The width of the vertical slit between the flexible plate 3b and the deformation suppression portions 3c, 3c, and the horizontal slit provided between the tip plates 3e, 3e at the ends (upper or lower ends) of the deformation suppression portions 3c, 3c and the web toe stiffening plates 3f, 3f of the support column 3 are set according to the expected inclination of the support column 3 and the amount of rotation of the end of the truss beam 2, so that when the inclination of the flexible plate 3b reaches the set value, it comes into contact with the deformation suppression portions 3c, 3c, and further inclination of the flexible plate 3b is suppressed. If the inclination of the flexible plate 3b becomes too large, the flexible plate 3b is more likely to buckle due to eccentric compression, so the width of the vertical slit between the deformation suppression portions 3c, 3c must be kept to the minimum necessary dimension.

[0039] In the third embodiment, the only bending resistance element in the flexible portion 3a is a single flexible plate 3b, and therefore the rotational (bending) rigidity of the flexible portion 3a is significantly smaller than in the first and second embodiments, so it can be said that the effect of reducing the thrust of the base of the support column 3 is greater.

[0040] In the first to third embodiments, the support column 3 is connected to the upper chord of the truss beam 2, but it goes without saying that the present invention can also be applied when the flexible portion 3a of the column head of the support column 3 is located at the lower chord of the truss beam 2, as shown in Figure 10(a), or at the middle of the height of the truss beam 2 (at the lattice material attachment portion), as shown in Figure 10(b).

[0041] Figure 11 shows an example of calculating the rotation angle θ that occurs when truss beam 2 is deflected by a uniformly distributed vertical load w at the end of truss beam 2. Assuming that the span L = 30 m, the effective depth of truss beam 2 (dimension between the axes of the upper and lower chord members) = 2 m, the size of the upper and lower chord members is H-200 × 200 × 8 × 12, and the uniformly distributed vertical load w = 1.0 t / m, the rotation angle θ is approximately 1 / 239 radian.

[0042] At this time, the rotation angle of the deformation suppression portions 3c, 3c at the head of the support column 3 is also approximately θ, so if the length of the flexible portion 3a is 20cm, the horizontal displacement of the tip (the corner at the bottom end in Figure 7(c)) due to the rotation of the deformation suppression portion 3c is approximately 20cm / 239 = 0.084cm. In addition to the vertical load, the rotation of the deformation suppression portions 3c, 3c caused by earthquakes, etc. must also be taken into account, so in this calculation example, it is thought that the gap dimension between the deformation suppression portion 3c and the flexible plate 3b should be approximately 0.2 to 0.3cm to allow for some leeway. [Industrial Applicability]

[0043] The present invention provides a simple and inexpensive truss beam support column structure that can minimize the thrust generated at the base of the support column in a roof frame consisting of truss beams, even when the support column length of the truss beam is as short as the length of the truss beam, and also contributes to suppressing cost increases for the lower structural columns because the load burden on the lower structural columns that support the roof frame is reduced. [Explanation of symbols]

[0044] 1: Roof frame 2: Truss beam 3: Support pillar 3a: Flexible part 3b: Flexible plate 3c: Deformation suppression section 3d: Gusset plate 3e: Tip plate 3f: Web toe stiffening plate 4: Lower structure column 5: Anchor bolt V1: Vertical brace V2: Roof brace θ: rotation angle

Claims

1. A truss beam support column structure, characterized in that in a roof frame consisting of a truss beam, a flexible section made of a flexible plate whose thickness direction coincides with the span direction of the truss beam is formed at the column head or column base of the support column supporting the truss beam, with a predetermined length in the material axis direction of the support column.

2. 2. The support column structure of a truss beam according to claim 1, wherein when the joint position between the support column and the truss beam is only at the upper chord portion of the truss beam, the flexible portion is provided at the column head or column base of the support column.

3. In the support column structure of a truss beam described in claim 1, when the joint position between the support column and the truss beam is only at the lower chord portion of the truss beam or only at the lattice material attachment portion in the middle of the truss beam height, the flexible portion is provided at the column head or column base of the support column.

4. 2. A design method for a support column structure of a truss beam according to claim 1, characterized in that the flexible portion formed at the column head or column base of the support column supporting the truss beam is composed of one or more flexible plates, and a deformation suppression portion that suppresses deformation of the flexible plate is provided on one or both sides of the flexible plate, and the gap dimension between the flexible plate and the deformation suppression portion is set according to the amount of inclination or amount of rotation of the truss beam end expected in the support column due to a vertical load or horizontal load applied to the roof frame.

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