JP2022156474A - Reinforcing structure for cylindrical structure and reinforced cylindrical structure having the same - Google Patents

Abstract

To provide reinforcing structure of a cylindrical structure capable of extremely rationally reinforcing a hollow cylindrical structure with a lower end part fixed and an upper end part opened against wind force acting on the cylindrical structure, and a reinforced cylindrical structure provided with the same.SOLUTION: In reinforcing structure of a cylindrical structure for reinforcing a hollow cylindrical structure with a lower end part fixed and an upper end part opened against wind force acting on the cylindrical structure, a reinforcing member for applying horizontal force Fn toward the outside in the radial direction of the cylindrical structure is attached to at least one place of the upper end part; the horizontal force Fn applied by the reinforcing member is set to satisfy the relation of Fn≥√ 3*HR(W-pcr) concerning a buckling resistance pcr of the cylindrical structure and a design wind force W. Where H is the height of the cylindrical structure, and R is the radius of the cylindrical structure.SELECTED DRAWING: Figure 1

Description

The present invention provides a reinforcing structure for a cylindrical structure that reinforces a hollow cylindrical structure having a fixed lower end and an open upper end against wind force acting on the cylindrical structure, and the same. It relates to reinforced cylindrical structures.

Conventionally, when constructing a cylindrical structure such as a floating roof type cylindrical oil tank or a dome type flat bottom cylindrical tank, the walls of the cylindrical structure are raised in order from the bottom in order, and construction such as welding and inspection is performed. proceed. A cylindrical structure that is in the process of being constructed does not yet have a roof on its upper end, and the rigidity of the cylindrical structure wall in the out-of-plane direction is low. The walls of cylindrical structures may buckle and collapse when subjected to wind pressure perpendicular to the vertical direction.

In addition, steel plate cells, which are cylindrical shells made of steel plates, are also used in embedded steel plate cell construction methods applied to quay walls of harbors and the like. The steel plate cells are manufactured in advance at a location different from the construction site, and are sequentially transported to the construction site according to the construction process. The conveyed steel plate cell is temporarily placed at the construction site for a certain period of time. At this time, the steel plate cell becomes a cylindrical structure with only the lower end fixed and the upper end opened. When the temporarily placed steel plate cell receives wind pressure perpendicular to the wall surface during strong winds, the wall surface of the steel plate cell may buckle and collapse.

Figures 5(a) to 5(c) show examples of the results obtained by time history response analysis of the buckling phenomenon that occurs when wind force acts on a hollow cylindrical structure with an open upper end. ). In such a cylindrical structure, since the out-of-plane rigidity of the wall surface is low, as shown in FIG. As shown in c), the deformation mode is such that the windward portion of the wall surface of the cylindrical structure collapses as a whole.

In order to prevent such a buckling phenomenon, a cylindrical structure with an open top needs to be reinforced against strong winds.

In a conventional reinforcement structure for a cylindrical structure, for example, as shown in the longitudinal sectional view of FIG. 6(a) and the plan view of FIG. A plurality of wires 81 are stretched radially in plan view between jigs and anchors 82 such as dikes to reinforce the cylindrical structure to withstand the surface load acting on the wall surface of the cylindrical structure during strong winds. Structure 8. Each wire 81 has one end connected to the upper end 5U of the cylindrical structure 5 and the other end fixed to the anchor 82, and stretched between the upper end 5U of the cylindrical structure 5 and the anchor 82. be done. Scaffolding for constructing the cylindrical structure 5 is often installed inside the cylindrical structure 5, so the wires 81 are generally stretched outside the cylindrical structure 5 instead of inside. is.

As another example of a conventional reinforcement structure for a cylindrical structure, Patent Document 1 discloses a cylindrical structure as shown in the longitudinal sectional view of FIG. 7(a) and the plan view of FIG. 7(b). A temporary scaffolding 91 is installed in a ring shape on the inner peripheral surface of the upper end part of the cylindrical structure 5 during construction to function as a reinforcing ring, and an outer corridor and tension ring 92 is temporarily installed on the outer wall surface of the cylindrical structure 5 that has been constructed. A stiffening structure 9 for a cylindrical structure is disclosed for assembly.

Further, as still another example of a conventional reinforcement structure for a cylindrical structure, Patent Document 2 discloses that a wire is attached only to a range that does not cover the entire circumference of the side plate of a cylindrical structure and faces prevailing winds. is disclosed.

JP-A-2000-120276 JP 2018-76112 A

However, none of the above-mentioned conventional reinforcement structures for cylindrical structures take into consideration the wind force generation mechanism during strong winds. Also, it is not clear how much strength should be given to reinforcing members such as tension rings. In other words, in the conventional reinforcement structure for cylindrical structures, detailed studies have not been conducted on how to set the yield strength (strength, size, number) of the reinforcing members attached to the cylindrical structure. The yield strength of members is designed with an excessive safety factor, which increases construction costs and reduces the efficiency of construction work.

In view of the above problems, the present invention provides a hollow cylindrical structure having a fixed lower end and an open upper end, which is very rationally reinforced against the wind force acting on the cylindrical structure. It is an object of the present invention to provide a reinforcing structure for a cylindrical structure that is capable of

In order to solve the above problems, a reinforcing structure for a cylindrical structure and a reinforcing cylindrical structure including the same according to the present invention have the following features.

[1] A reinforcing structure for a cylindrical structure that reinforces a hollow cylindrical structure having a fixed lower end and an open upper end against wind force acting on the cylindrical structure, A reinforcing member is attached to at least one part of the upper end to apply a horizontal force toward the radially outer side of the cylindrical structure, and the horizontal strength _Fn of the reinforcing member is applied to the buckling of the cylindrical structure. A reinforcing structure for a cylindrical structure characterized by satisfying the relationship of the following formula (1) with respect to proof stress _pcr and design wind power W.

F _n ≧√3·HR(W−p _cr ) (1)
where H is the height of the cylindrical structure and R is the radius of the cylindrical structure.

[2] The reinforcing structure for a cylindrical structure according to [1], wherein the buckling strength p _cr is calculated by the following equation (2).

p _cr =0.82α(H/D) ⁻¹ (R/t) ^−2.5 (2)
however,
α=π ² E/{24(1−ν ² ) ^0.75 } (3)
where D is the diameter of the cylindrical structure, t is the thickness of the cylindrical structure, E is the Young's modulus of the cylindrical structure, and ν is the Poisson's ratio of the cylindrical structure.

[3] The reinforcing structure for a cylindrical structure according to [1] or [2], wherein the design wind power W is calculated by the following formula (4).

W=C _f0 ×G _f ×(1/2)ρV ² (4)
where C _f0 is the wind force coefficient at the stagnation point, G _f is the gust influence coefficient, ρ is the air density, and V is the design wind speed.

[4] The reinforcing structure for a cylindrical structure according to any one of [1] to [3], wherein the reinforcing members are attached to the upper end portion at six points in the circumferential direction.

[5] The reinforcing member according to [4], wherein the reinforcing member is arranged at an interval of 55° or more and 65° or less in the circumferential direction of the upper end portion with respect to the central axis of the cylindrical structure. Reinforcement structure for cylindrical structures.

[6] A cylindrical structure that reinforces a hollow cylindrical structure with a fixed lower end and an open upper end against wind forces acting on the cylindrical structure; A reinforced cylindrical structure characterized by comprising a reinforcing structure for a cylindrical structure according to any one of [1] to [5], which is reinforced.

According to the reinforcing structure for a cylindrical structure of the present invention and the reinforcing cylindrical structure provided with the same, the horizontal strength Fn of the reinforcing member that applies a horizontal force toward the radially outer side of the cylindrical structure is _equal to that of the cylindrical structure. The horizontal strength of the reinforcing members is efficiently exerted by setting the buckling strength _pcr of the structure and the design wind force W so as to satisfy the relationship of formula (1), making the reinforcement structure extremely rational. becomes. Therefore, it becomes possible to design the yield strength (strength, size, number) of the reinforcing members with a reasonable safety factor, thereby suppressing the construction cost and improving the efficiency of the construction work.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows an example of the reinforcement structure of the cylindrical structure which concerns on this invention, and a reinforcement cylindrical structure provided with the same, (a) is an elevation view, (b) is a top view. 4 _is a graph showing the relationship between the range of surface load _pn considered in calculating the horizontal strength Fn of a reinforcing member and the horizontal strength _Fn calculated based thereon. It is a figure which shows another example of the reinforcement structure of the cylindrical structure which concerns on this invention, and a reinforcement cylindrical structure provided with the same, (a) is an elevation view, (b) is a top view. It is a figure which shows another example of the reinforcement structure of the cylindrical structure which concerns on this invention, and the reinforcement cylindrical structure provided with the same, (a) is an elevation view, (b) is a top view. It is a figure which shows the example of the buckling which wind force acts on a cylindrical structure, and generate|occur|produces. It is a figure which shows an example of the reinforcement structure of the conventional cylindrical structure, (a) is an elevation view, (b) is a top view. It is a figure which shows another example of the reinforcement structure of the conventional cylindrical structure, (a) is an elevation view, (b) is a top view.

Embodiments of a reinforcing structure for a cylindrical structure according to the present invention and a reinforcing cylindrical structure including the same will be described below with reference to the drawings.

As shown in the longitudinal sectional view of FIG. 1(a) and the plan view of FIG. 1(b), the reinforcing structure 1 for a cylindrical structure according to the present embodiment has a lower end portion 5L fixed to the ground and an upper end portion is to reinforce the open hollow cylindrical structure 5 against the wind force acting on this cylindrical structure.

Further, the reinforced cylindrical structure 10 of the present embodiment comprises a cylindrical structure 5 and the reinforcing structure 1 for reinforcing the cylindrical structure 5. be.

As shown in FIGS. 1(a) and 1(b), a wire (reinforcing member) for applying a horizontal force radially outward of the cylindrical structure 5 is provided on the upper end portion 5U of the cylindrical structure 5. 11 is attached. Specifically, as shown in FIG. 1(a), six wires 11 are stretched between the upper end portion 5U of the cylindrical structure 5 and anchors 12 installed on the ground for ensuring reaction force. is suspended. As shown in FIG. 1(b), the six wires 11 are arranged in the circumferential direction of the upper end portion 5U of the cylindrical structure 5 so as to be arranged radially with respect to the central axis 5C of the cylindrical structure 5 in plan view. They are arranged at intervals of 60°.

The horizontal strength F _n of each wire 11 that applies a horizontal force toward the radially outer side of the cylindrical structure 5 is obtained by the following formula (1) with respect to the buckling strength p _cr of the cylindrical structure 5 and the design wind power W is set to satisfy the relationship of

F _n ≧√3·HR(W−p _cr ) (1)
However, H is the height of the cylindrical structure 5 and R is the radius of the cylindrical structure 5 .

(1) The relationship of the formula will be explained below.

In order to prevent buckling of the cylindrical structure 5 due to the buckling strength _pcr of the cylindrical structure 5 falling below the design wind force W, the surface load p _n that the reinforcing member (wire) 11 should bear is
p _n =W−p _cr (5)
is. Here, in the present invention, the characteristic of the wind force distribution acting on the cylindrical structure 5 is used to convert the surface load p _n to be borne by the reinforcing member (wire) 11 into the horizontal strength F _n to be provided by the reinforcing member. , and the relationship of the formula (1) is obtained.

The wind force acting on the wall surface of the cylindrical structure 5 varies spatially and temporally in the height direction and the circumferential direction, and the characteristics of the wind force distribution acting on the cylindrical structure 5 vary greatly depending on the properties of the inflowing airflow. Change. Here, as a result of extensive research, the inventors of the present invention have found that the buckling phenomenon caused by the wind force acting on the cylindrical structure 5 is predominantly affected by the positive wind force on the windward side. When the windward front is θ=0° with respect to the central axis 5C of the object 5, the positive wind force acting in the circumferential direction of the cylindrical structure 5 in the range of −60°≦θ≦+60° It was found to have a dominant effect on the buckling phenomenon of the structure 5.

From this, assuming that the wind force distribution is uniform in the height direction, the horizontal strength Fn that the reinforcing member (wire) 11 should have _is the surface load _pn that the reinforcing member should bear. The θ = 0° direction component of the wind force acting in the circumferential direction of the object 5 in the range of -60° ≤ θ ≤ +60° is integrated and calculated as shown in the following formula (1'). Formula relations are derived.

FIG. 2 shows the case _{where the range of the surface load p n to} be considered in the calculation of the horizontal strength Fn of the above equation (1′) is changed from −60° ≤ θ ≤ +60°, the reinforcing member (wire) 11 It is shown graphically how the horizontal yield strength F _n that should be provided by . However, in FIG. 2, the horizontal strength F _n on the vertical axis is normalized by HR/(W−p _cr ).

As shown in FIG. 2, when the range of the surface load _pn to be considered is wider than ±60°, the horizontal strength _Fn that the reinforcing member (wire) 11 should have exceeds the required horizontal force, resulting in inefficient Reinforcement structure. On the other hand, if the range of the surface load _pn to be considered is narrower than ±60°, the horizontal strength _Fn that the reinforcing member (wire) 11 should have falls below the required horizontal force, resulting in insufficient reinforcement. Therefore, in the present invention, as shown in formulas (1) and (1'), of the surface load _pn to be borne by the reinforcing member, -60° ≤ θ ≤ +60° in the circumferential direction of the cylindrical structure 5 The horizontal strength _Fn that the reinforcing member (wire) 11 should have is calculated in consideration of the wind force acting in the range of .

In the above equation (1), the buckling strength p _cr of the cylindrical structure 5 is determined by the inventors'"Dynamic Buckling Characteristics of Cylindrical Storage Tank Subjected to Fluctuating Wind Forces" (Proceedings of the Japan Wind Engineering Society, 2018 April 2004, Vol. 43, No. 2, pp. _1-10 ), the following ( 2) Calculated as shown in the formula.

p _cr =0.82α(H/D) ⁻¹ (R/t) ^−2.5 (2)
however,
α=π ² E/{24(1−ν ² ) ^0.75 } (3)
where D is the diameter of the cylindrical structure 5, t is the thickness of the cylindrical structure 5, E is the Young's modulus of the cylindrical structure 5, and ν is the Poisson's ratio of the cylindrical structure 5.

Further, the wind force W acting on the cylindrical structure is represented by the following formula (4).

W=C _f0 ×G _f ×(1/2)ρV ² (4)
where C _f0 is the wind force coefficient at the stagnation point, G _f is the gust influence coefficient, ρ is the air density, and V is the design wind speed.

According to the reinforcing structure 1 for a cylindrical structure of the present embodiment and the reinforcing cylindrical structure 10 including the same, the wire (reinforcing member) 11 for applying a horizontal force toward the radially outer side of the cylindrical structure 5 is set so as to satisfy the relationship of formula (1) with _{respect to the buckling strength p cr of} the cylindrical structure 5 and the design wind force W, so that the horizontal strength of the wire 11 is efficient , and it becomes an extremely rational reinforcement structure. Therefore, it is possible to design the yield strength (strength, size, number) of the wires 11 with a reasonable safety factor, reduce the construction cost, and improve the efficiency of the construction work. Further, since the cylindrical structure 5 has a fixed lower end and an open upper end, by attaching a wire (reinforcing member) 11 to the upper end 5U of the cylindrical structure 5, the cylindrical structure 5 can be wind resistance can be significantly improved.

In addition, in the calculation of the horizontal strength F _n of the above equation (1′), the range of the surface load p _n to be considered is set to 60°≦θ≦+60°. Like the form, it is necessary and sufficient if they are installed at intervals of 60° in the circumferential direction of the upper end portion 5U of the cylindrical structure 5 . If this arrangement interval is in the range of 55° or more and 65° or less, the rationality of the reinforcing structure 1 for the cylindrical structure is ensured.

It should be noted that the reinforcing structure for a cylindrical structure and the reinforcing cylindrical structure including the same according to the present invention are not limited to the above-described embodiments, and can be appropriately modified within the scope of the present invention. be. For example, as in the reinforcing structure 2 of the cylindrical structure shown in the vertical cross-sectional view of FIG. 3(a) and the plan view of FIG. A diagonal member 21 is installed between the upper end portion 5U of the structure 5 and the ground inside the cylindrical structure 5 to apply a horizontal force radially outward to the upper end portion 5U of the cylindrical structure 5. You may make it Alternatively, as in the reinforcing structure 3 of the cylindrical structure shown in the vertical cross-sectional view of FIG. 4(a) and the plan view of FIG. A horizontal truss member 31 may be installed horizontally inside the upper end portion 5U of the structure 5 to apply a horizontal force to the upper end portion 5U of the cylindrical structure 5 radially outward.

Reinforcement structure of cylindrical structure 1, 2, 3
Reinforced cylindrical structure 10, 20, 30
Reinforcing member (wire) 11
Reinforcement member (diagonal member) 21
Reinforcing member (horizontal truss member) 31
Cylindrical structure 5
Lower end 5L
Upper end 5U
central axis 5C

Claims (6)

A cylindrical structure reinforcing structure for reinforcing a hollow cylindrical structure having a fixed lower end and an open upper end against wind force acting on the cylindrical structure,
A reinforcing member is attached to at least one portion of the upper end portion to apply a horizontal force toward the radially outer side of the cylindrical structure,
A reinforcing structure for a cylindrical structure, wherein the horizontal strength F _n of the reinforcing member satisfies the relationship of the following formula (1) with respect to the buckling strength p _cr of the cylindrical structure and the design wind force W.
F _n ≧√3·HR(W−p _cr ) (1)
where H is the height of the cylindrical structure and R is the radius of the cylindrical structure. 2. The reinforcing structure of a cylindrical structure according to claim 1, wherein the buckling strength _pcr is calculated by the following formula (2).
p _cr =0.82α(H/D) ⁻¹ (R/t) ^−2.5 (2)
however,
α=π ² E/{24(1−ν ² ) ^0.75 } (3)
where D is the diameter of the cylindrical structure, t is the thickness of the cylindrical structure, E is the Young's modulus of the cylindrical structure, and ν is the Poisson's ratio of the cylindrical structure. The reinforcing structure for a cylindrical structure according to claim 1 or 2, wherein the design wind power W is calculated by the following formula (4).
W=C _f0 ×G _f ×(1/2)ρV ² (4)
where C _f0 is the wind force coefficient at the stagnation point, G _f is the gust influence coefficient, ρ is the air density, and V is the design wind speed. The reinforcing structure for a cylindrical structure according to any one of claims 1 to 3, wherein said reinforcing members are attached at six locations in the circumferential direction of said upper end portion. 5. The cylindrical structure according to claim 4, wherein the reinforcing members are arranged at intervals of 55° or more and 65° or less in the circumferential direction of the upper end with respect to the central axis of the cylindrical structure. Reinforcement structure of things. a cylindrical structure that reinforces a hollow cylindrical structure with a fixed lower end and an open upper end against wind forces acting on the cylindrical structure;
A reinforced cylindrical structure, comprising: a reinforcing structure for a cylindrical structure according to any one of claims 1 to 5, which reinforces the cylindrical structure.

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