JP4304882B2 - Hull structure - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a hull structure, and more particularly, to a structure of a frame of a portion where longages of a hull are not parallel.
[0002]
[Prior art]
3 is a partial plan view of the hull structure at the bottom of the ship, FIG. 4 is a view taken along the line AA in FIG. 3, and FIG. 5 is a view taken along the arrow B in FIG. In these drawings, 1 is a ship bottom plate, 2 is a transformer frame, and 3 is a longi. The transformer frame 2 extends in the width direction of the hull and is welded to the ship bottom plate 1 at a required interval in the longitudinal direction. Longi 3 has a T-shape with a face plate 3a at the upper end. The transformer frame 2 has a height three to four times that of the longi 3, and a T-shaped groove through which the longe 3 passes is provided below the transformer frame 2. The longi 3 extends under the transformer frame 2 in the longitudinal direction of the hull, and is welded to the ship bottom plate 1 at a predetermined interval in the width direction. The transframe 2 and the long 3 form a grid-like frame.
[0003]
As shown in FIG. 3, the hull is bent inwardly at the portion where the width of the bottom of the hull narrows in the direction of the bow or stern. The longi 3b is thinned out. The thinned out long 3b is joined to the header 4 at an intermediate position between the transformer frames 2 and stopped. The header 4 is provided in order to share the load applied to the longage 3b stopped at the middle by the longages 3c and 3c on both sides joined to both ends of the header 4. The header 4 is a flat bar having a uniform height or its play. A reinforcing face material is provided on the side (upper side). Reference numeral 5 denotes curling. In the portion of the thinned out long side 3b on the other side of the transformer frame 2, the distance between the longes 3c and 3c is widened.
[0004]
[Problems to be solved by the invention]
The height of the uniform header 4 shown in FIGS. 4 and 5 is determined based on the following factors.
(1) Required height of the joint 8 required from the shear strength of the joint (welded part) 8 between the header 4 and the longe 3b,
(2) Required height for obtaining the section modulus necessary to counter the bending moment that the header 4 itself receives,
(3) The required height to obtain the cross-sectional area necessary to counter the shearing force received by the header 4 itself,
The height of the header 4 needs the maximum value of these required heights.
(1) is necessary only for the joint 8 between the header 4 and the longi 3b, and (2) is the maximum at the joint 8 between the header 4 and the longi 3b, and decreases toward both ends. ) Requires the header 4 to be uniform over the entire length.
[0005]
In general, (1) and (2) are large and (3) is small. In the case of the conventional uniform-height header 4, the overall height is increased to satisfy (1) or (2). For example, the height of the long 3b is 450 mm and the height of the header 4 is 350 mm. Moreover, in order not to buckle with respect to the height, the plate thickness must be increased. For example, the thickness of a header having a height of 350 mm needs to be 17.5 mm. Furthermore, in order to satisfy (1), it is necessary to take sufficient welding strength per unit length, which takes time for designing. In order to lower the header 4, as shown in FIG. 5, it is necessary to provide a notch 3 d at the front end of the longe 3 b. Since it becomes an acute angle α, it becomes difficult to weld the upper surface of the distal end of the longe 3b and the joint surface 8 of the header 4, and the shear stress of that part is also marginal, so that from that part to the distal end of the longe 3b as shown in FIG. Damage such as a crack c is likely to occur.
[0006]
The present invention has been devised in view of such problems of the prior art. By devising the shape of the header, (1) the notch of the longi tip is eliminated and the trouble is eliminated, and (2) the header and the longi (3) The thickness required for buckling of the header can be reduced, and (4) the shear stress of the joint is required. It is an object of the present invention to provide a hull structure having the shape of a header that can save the effort of calculating the height of the header.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the hull structure of the present invention includes a transformer frame that extends in the width direction of the hull and is welded to the bottom plate at a predetermined interval in the longitudinal direction, and penetrates below the transformer frame. In a hull structure that extends in the longitudinal direction of the hull and has a longe welded to the bottom plate at a required interval in the width direction, the portion where the width of the hull narrows in the direction of the bow or stern In addition to narrowing the interval between each longe, and when thinning out the number of longes, it has a header that is joined to the end of the longe to be thinned out and provided almost in parallel with the transformer frame. At the part to be joined, it is almost the same height as the longe, and gradually decreases toward both ends to be joined to the longe on both sides.
[0008]
It is preferable that the header has a high flat portion at an intermediate portion joined to the longe, has an inclined portion that descends outward on both sides thereof, and further has a low flat portion on both sides thereof.
[0009]
The angle of the inclined portion with respect to the horizontal is preferably approximately 30 °.
[0010]
Next, the operation of the present invention will be described in bullets.
(1) Since the height of the header and the longe is substantially equal at the portion where the header is joined to the longe, it is not necessary to cut out the tip of the longe, and the labor of notching can be saved.
(2) The header is high only where necessary, and the height at both ends may be high enough to resist the shearing force applied to the header itself. Therefore, the overall height is lowered, and the height of the easily buckling portion between the header / longi junction and the header end is lowered, so that the wall thickness required for buckling is reduced. be able to. For this reason, the amount of material is reduced and the weld length at both ends is shortened, resulting in cost reduction.
(3) Since the angle formed between the upper side of the long end and the joint surface of the header is a right angle, welding is easy. In addition, since the weld length is sufficient, the shear stress of the welded portion can be reduced, the strength can be increased, and damage can be reduced. Therefore, it is not necessary to calculate the required header height from the shearing force of the welded portion, and the labor can be saved.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 3 is a partial plan view of the hull structure of the present invention, and is the same as that already described as the conventional example. 1 is an AA arrow view of FIG. 3, and FIG. 2 is an arrow B view of FIG. In these drawings, parts common to those shown in FIGS. 3 to 5 used for explaining the conventional example are denoted by the same reference numerals, and redundant description is omitted. In these drawings, 7 is a header used in the hull structure of the present invention. The header 7 is the highest at the part where it is joined to the longi 3b, and its height is substantially the same as that of the longi 3b. And it becomes low gradually toward the both ends joined to the longi 3c on both sides. If the shape of the upper side of the header 7 is a curve corresponding to the calculated stress, it will be difficult to manufacture. Therefore, as a practical shape, as shown in FIG. Inclined portions 7b and 7b descending outward and lower flat portions 7c and 7c on both sides thereof. Further, an R of about 150 mm is provided between the inclined portion 7b and the low flat portion in order to avoid stress concentration. The joining of the longines 3b and 3c and the header 7 is a normal fillet weld. The width of the high flat portion is preferably about 100 mm, and the angle between the inclined portion and the horizontal line is preferably about 30 °.
[0012]
The effect | action of this embodiment is demonstrated with a bullet.
(1) In the portion 8 where the header 7 is joined to the longe 3b, the height of the header 7 and the longe 3b is substantially equal, so there is no need for the notch 3d at the tip of the longe 3b as shown in FIG. Saves time and effort.
(2) The header 7 is high only where necessary, and the low flat portion 7c may have a height that opposes the shearing force received by the header 7 itself. Accordingly, the overall height is reduced, and an intermediate buckling portion between the joint portion 8 of the header 7 and the longe 3b and the end portion 7d of the header 7, for example, the boundary between the inclined portion 7b and the low flat portion 7c. Since the height of the vicinity becomes low, the wall thickness required for buckling can be reduced. For this reason, the amount of material is reduced, and the weld length of both end portions 7d is shortened, resulting in cost reduction.
(3) Since the angle formed by the upper edge of the longe 3b and the joint 8 of the header 7 is a right angle, welding is easy. In addition, since the weld length is sufficient, the shear stress of the welded portion can be reduced, the strength can be increased, and damage can be reduced. Therefore, it is not necessary to calculate the required height of the header 7 from the shearing force of the welded portion, and it is possible to save time and effort.
[0013]
【Example】
Hereinafter, the specific shape of the header 7 of the hull structure of the present invention will be described using calculation formulas. A header as shown in FIG. 6 is considered with a header length of l. FIG. 6 is a view taken in the direction of arrows AA in FIG. For simplicity, the load point is at the center of span l.
The bending moment M is
M = Px / 2 (1)
Shear force F is
F = P / 2 (2)
If the thickness of the header is t (a constant value) and the height is d (x) (a function of x), the section modulus Z (x) (a function of x) is
Z (x) = td ² (x) / 3
The section coefficient Z (x) is given as an empirical value as an approximate value on the upper side of the section coefficient of an inverted T-shaped section formed by cutting out and combining appropriate widths of the header 7 and the ship bottom plate 1.
Therefore, the tensile (compression) stress σ is
σ = M / Z (x) = 3Px / 2td ² (x)
Therefore,
d (x) = √ (3Px / 2tδ) (3)
On the other hand, the shear stress τ is
τ = F / td (x) = P / 2td (x)
Therefore,
d (x) = P / 2tτ (4)
The optimum shape is obtained by connecting the larger ones of Equations (3) and (4), and the shape is as shown by the solid line in FIG. 8, as will be described later.
[0014]
As a typical example, the size of the header 7 is estimated for the hull structure of the bottom of the ship shown in the plan view of FIG. Consider a case where 200 KN / m ² pressure is applied to the bottom plate 1. Since this load is equally received by the longe 3b and the longes 3c and 3c on both sides thereof, the load applied to the longe 3b is 200 × (1.6 + 1.2) /2×2=200×0.7KN per unit length. / M. Since it is considered that the longe 3b is supported by the fixed support on the transformer frame 2 side and the rotary support on the header 7 side, 5/8 of the total load applied to the longe 3b is borne by the transformer frame 2 side. Is loaded on the header 7 side.
Therefore,
P = 200 × 0.7m × 4m × 3/8 = 210KN
The thickness of the header 7 is 16 mm, the allowable tensile (compression) stress σ and the allowable shear stress τ, and δ = 120 N / mm ² respectively.
Z = 70 N / mm ²
Calculate as follows.
If this is applied to equation (3),
d (x) = √ (3 × 210 × 10 ³ x / 2 × 16 × 120) = 12.8√x (mm), when applied to (4),
^{d (x) = 210 × 10} 3/2 × 16 × 70 = 94 (mm),
The above is shown in the graph as shown by the solid line in FIG. That is, for x = 0 to x = 54 mm, d (x) = 94 mm, for x = 54 mm to x = 600 mm, d (x) = 12.8√x, and for x = 600 mm to x = 1200 mm, x = 0 to x = 600 mm.
[0015]
However, since the shape shown by the solid line is difficult to manufacture and is not practical, the shape shown by the one-dot chain line in FIG. That is, the height of the flat portion 7a at the center is 350 mm which is the same as the height of the longitudinal 3b, the width is 100 mm, the inclined portions 7b descending outward on both sides thereof, and the low flat portions 7c on both sides thereof. have. The height of the low flat part is 250 mm. An R of about 150 mm is added between the inclined portion 7b and the low flat portion 7c to avoid stress concentration. The inclination angle of the inclined portion 7b is 30 °.
[0016]
Next, the slope of the slope is calculated.
Differentiating because d (x) = √ (3Px / 2tσ),
d ′ (x) = √ (3P / 8tσx) (5)
It becomes. Therefore, when P is large and t · σ · x is small, the slope becomes steep.
The maximum value Pmax of P which can be considered is calculated | required.
The pressure applied to the ship bottom plate 1 is 300 KN / m ² , and the distance between the transformer frames 2 is 6000 mm. Maximum moment when is under uniform distributed load on a beam may, when both ends of the beams of the fixed support is M = wl ^2/12, if one end of the beams at the other end is rotated supported by the fixed support M = wl ^2/8 So interval to equal the maximum moment header 7 and the transformer frame 2 may be any √ (2/3) of the distance between the transformer frame 2. When the width of the bottom plate for calculating the load per unit length applied to the longe 3b (1/2 of the average width between the longes 3c and 3c) is 950 mm,
Pmax = 300 × √ (2/3) × 6.0 × 0.95 × (3/8) = 524KN The minimum value of the thickness t of the header is tmin,
tmin = 12mm
The minimum value σmin (mild steel) of allowable tensile (compression) stress is σmin = 120 N / mm ² . Since the minimum distance between the longi 3b and the longi 3c is 450 mm in terms of welding workability, the inclination at the joint between the longi 3b and the header 7 becomes a maximum value when xmin = 450 mm. Substituting these numbers into equation (5) gives the maximum slope:
√ (3 × 524 × 10 ³ /8×12×120×450)=0.551
tan ⁻¹ (0.551) = 28.8
Therefore, if the inclination angle is selected to be 30 ° and the bending stress is satisfied at the foot of the inclined portion 7b, the one-dot chain line in FIG. 8 does not bite below the solid line, and the header is satisfactory in strength. It can be seen that it is.
[0017]
The present invention is not limited to the embodiments and examples described above, and various modifications can be made without departing from the gist of the present invention. For example, in the embodiment, an example in which the ship bottom plate is applied has been described. However, the present invention is not limited to the ship bottom plate but can be applied to an upper deck, an inner bottom plate, a longitudinal partition wall, and the like. Furthermore, when applied to a horizontal partition, it can be read as the longitudinal direction.
[0018]
【The invention's effect】
As described above, the hull structure of the present invention has a header having a shape in which the joining portion between the header and the longe is substantially the same height as the longe and gradually decreases toward both ends joining the longe on both sides. Therefore, it has the following excellent effects.
(1) Since the height of the header and the longe is substantially equal at the portion where the header is joined to the longe, it is not necessary to cut out the tip of the longe, and the labor of notching can be saved.
(2) The header is high only where necessary, and the height at both ends may be high enough to resist the shearing force applied to the header itself. Therefore, the overall height is lowered, and the height of the easily buckling portion between the header / longi junction and the header end is lowered, so that the wall thickness required for buckling is reduced. be able to. For this reason, the amount of material is reduced and the weld length at both ends is shortened, resulting in cost reduction.
(3) Since the angle formed between the upper side of the long end and the joint surface of the header is a right angle, welding is easy. In addition, since the weld length is sufficient, the shear stress of the welded portion can be reduced, the strength can be increased, and damage can be reduced. Therefore, it is not necessary to calculate the required header height from the shearing force of the welded portion, and the labor can be saved.
[Brief description of the drawings]
FIG. 1 is a front view of a header of a hull structure according to the present invention.
FIG. 2 is a side view of a header and a longage of the hull structure of the present invention.
FIG. 3 is a partial plan view of a hull structure of a ship bottom portion.
FIG. 4 is a front view of a conventional hull structure header.
FIG. 5 is a side view of a conventional hull structure header and longage.
FIG. 6 is a front view of a hull structure header according to the present invention, and is a drawing for calculating the dimensions of the header.
FIG. 7 is a partial plan view of the hull structure of the ship bottom portion, and is a drawing for calculating the dimensions of the header.
FIG. 8 is a drawing of an exemplary shape of a header.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Ship bottom board 2 Transformer frame 3 Longi 7 Header 7a High flat part 7b Inclined part 7c Low flat part 8 Joint part

Claims (3)

A transformer frame that extends in the width direction of the hull and provided at a required interval in the longitudinal direction, and extends below the transformer frame in the longitudinal direction of the hull and is provided at a required interval in the width direction. In the hull structure with longes, the longes close to the outside are folded inward at the narrowed part in the bow or stern direction to narrow the distance between the longes, and the number of longes is thinned out to prevent interference when going, substantially the same height as the transformer frame by joining the end of the longitudinals would have a header that is provided substantially in parallel, the header of the shape in the portion to be joined with longitudinals to be thinned out above and its longitudinals to be thinned out The hull structure is characterized by being gradually lowered toward both ends joined to the longes on both sides. The header has a high flat portion at an intermediate portion joined to the thinned out longe, an inclined portion that descends outward on both sides thereof, and a low flat portion on both sides thereof. Item 1. The hull structure according to item 1.   The hull structure according to claim 2, wherein an angle of the inclined portion with respect to the horizontal is approximately 30 °.

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