JPS5914394B2 - Tankers made of reinforced concrete, especially for transporting liquefied gases - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a one-piece hull made of reinforced concrete, especially for the transportation of liquefied gas, which is divided into at least two parts, which are arranged side by side in the cross section of the hull, and which extend in the longitudinal direction. ,
It relates to a tanker having a tank space separated by a transverse watertight bulkhead and connected to each other by a deck and a bottom plate.

Tankers for the transport of liquefied gases, if they are made of steel, must be equipped with special storage tanks for liquefied gases for safety reasons, which are made from low-temperature toughness steel and are mostly It is formed as a spherical tank.

Such tankers are particularly expensive to build and maintain, apart from the fact that the free tank space is not fully utilized.

Additionally, it is already known that reinforced concrete tankers are easier and cheaper to manufacture than steel tankers.

In the case of the known tanker, the hull consists of two cylindrical bodies, which are joined in the region of the longitudinal axis, so that in cross section there are three spaces, the outer two spaces being used as tank spaces. , the central space formed by the combination (
・Well, it will be used as a driving space.

The tank space is reinforced by a flat transverse waterproof bulkhead.

The deck, bottom plate, and outer wall side plates of the hull are reinforced both vertically and horizontally with steel bars.

When using reinforced concrete for the outer shell of a tanker for transporting liquefied gas, there is no need for safety equipment if a special storage tank is provided in the case of a steel tanker.

When concrete as a structural material comes into contact with a low-temperature liquid in an abnormal situation, the strength will not decrease due to total heat, but will warp and increase in strength.

The main challenge in the case of reinforced concrete or prestressed concrete hulls is how to cope with the fact that, compared to structures on the ground, the hull cross-section is subjected to significant alternating stresses in service due to external loads such as waves. That's the point.

The object of the invention is to create a possibility for constructing tankers, in particular for the transport of liquefied gases, simply, economically and with efficient use of materials.

The present invention solves the problem by adopting the following configuration in this type of tanker.

(a) In the cross-sectional shape of the outer shell plates of the hull 1 consisting of the deck 4, the bottom plate 3, and the outer wall side plates 2, 20 outer wall plates are continuous to the deck 4 and the bottom plate 3 at the corners.

The outer shell plates of the hull 1 are formed in such a way that the bending moment of the outer shell plates, which is applied from the lateral direction of the hull due to wave motion and cargo, is as small as possible during use. (b) The shell plate is also reinforced in the longitudinal direction with reinforcing bars and prestressing tension material, and in this case, the prestress in the longitudinal direction is due to wave motion. , be designed so that the maximum positive and negative bending moments received from the load are approximately equal when in use.

In the tanker to which the present invention is applied, the load-bearing shell plate of the hull consists of two three-dimensional half-frames symmetrical with respect to the longitudinal axis, consisting of the deck, the outer wall side plates, and the bottom plate in the transverse direction,
It is subjected to significant alternating stresses due to the pressure of the load acting from the inside to the outside, and the pressure due to the waves acting from the outside to the inside.

In the longitudinal direction, the hull has the effect of a box girder, the length of which corresponds to the total hull length.

Fundamental to the invention is the cross-sectional configuration of the hull, which is selected in such a way that the transverse bending moments caused by the water pressure on the one hand and by the cargo on the other hand are very small.

Furthermore, in addition to regular reinforcing steel, it is important to install PC tendons to introduce prestress.

In this case, the longitudinal prestress is reinforced in such a way that the maximum positive and negative bending moments in the longitudinal direction are approximately of the same magnitude.

In other words, the reinforcement is applied so that the bending moment is the same when the hull is subjected to wave motion from the center in the longitudinal direction and when it is subjected to wave motion from both the front and rear sides.

Also in this case, the reinforcing steel is susceptible to repeated compression and tension, and the structural material, reinforced concrete, along with prestressing, is utilized to its fullest in the three-dimensional stress state at any location, minimizing the required amount and associated weight. This brings about the advantage that it is possible to design the thickness of the board to be precise.

In the cross-sectional shape of the outer shell plate, the 20 outer wall plates continuously transition to the deck 4 and the bottom plate 3 in a gentle curve with no protrusions, so that the so-called ``corner portion'' is removed. There is no ring on the shell plate.

Therefore, reinforcing reinforcing bars and P are incorporated into this outer shell plate.

C6 tendons do not require bending and have the advantage of being elastically curved.

Furthermore, when reinforcing reinforcing bars are joined, the joined portion is subject to significant fatigue strength if there is a corner portion, but such fatigue strength does not occur in the present invention.

For the same reason, longitudinal reinforcement can basically be installed without joints along the entire length of the hull.

In the tanker according to the invention, the plates constituting the deck can be widened laterally beyond the point where they tangentially join the outer wall side plates.

The widening can be supported against the outer wall side panel and can also form an additional tank space in the area of this widening.

On the one hand, this widening of the deck surface provides advantages for the operation of the ship, since the usable deck surface becomes larger.

In addition, the presence of this widened portion makes the effective cross-sectional areas of the deck and bottom plate approximately equal in size, and their resistance to bending is also equal.

This also contributes to the maximum utilization of the structural material reinforced concrete.

If a transverse watertight bulkhead is required for reasons of safety against sinking in the tanker object of the invention, it is advantageous to form it as a double-curved arched shell.

In the case of the tanker object of the invention, the transverse watertight bulkhead has only a secondary significance with respect to the mechanical configuration of the ship.

It limits the uneven deflection of the outer and inner walls, which are already slight, from averaging out over the length of the hull.

Furthermore, it aids in the safety of the ship in case of emergency situations such as grounding, collision or war damage.

Forming the transverse waterproof bulkhead as a doubly curved arched shell or spherical surface makes it possible to save weight.

In other words, the original wall portion of the outer tank space and the transverse waterproof bulkhead as the arched shell work together to maintain the strength of the tank wall, and even if some tanks are flooded, Other compartments of the tank space will not be flooded.

This transverse waterproof bulkhead also serves to transmit the wave pressure applied in the longitudinal direction of the hull to both side walls of the tank, thereby preventing the tank space from being destroyed.

The formation of the transverse watertight bulkhead as an arched shell is also a prerequisite for being able to advantageously use such tankers for the transport of liquefied gases transported at temperatures of -162°C.

The walls delimiting the tank space for the transport of liquefied gas are provided with insulation against the penetration of cold air on their insides, and the transverse waterproof bulkheads on both sides.

In the outer wall side panels, the temperature drop from the outside temperature to the cold inner space occurs almost entirely in the insulation, but it is inevitable that the waterproof partition wall will be cooled despite the presence of the insulation.

This temperature gradient occurs continuously from the shell plate to the lowest point in the center of each waterproof bulkhead.

A flat structure will be subjected to unbearable temperature stress.

However, the arched shell elastically absorbs such stress by reducing its arch height.

The invention will be explained in more detail on the basis of embodiments shown in the drawings.

In the embodiment shown in the drawings, a tanker suitable for the transport of liquefied gas is shown, in which the outer wall side panels 2, the bottom panel 3 and the deck 4 of the hull 1 are made of solid plates made of reinforced concrete. ing.

In addition to regular reinforcing bars in the vertical and horizontal directions, these plates have
PC tension material is arranged to create prestress.

Reinforcements are not shown for better overall perspective.

The shell plate of the hull 1 encloses two main tank spaces 5 and 6.

In the central part of the hull 1, between tank spaces 5 and 6, in its upper part there is provided a storage space 7 which can be used for storing ballast water, and in its lower part a tank space 8 for fuel. provided.

The separating walls 9 for the tank space 7 in the central part are likewise constructed as reinforced concrete plates, but the interior of the hull is supplemented with transverse waterproof bulkheads 10 and auxiliary materials 11 provided at small intervals. Since the force is basically carried by the outer shell plates, these separating wall plates can be made thinner than the outer wall side plates 2.

All reinforcing bars are high strength steel, e.g. 5T135/150
, with a diameter of 16my++, and is supplied rolled up onto a drum in lengths of 250m or more, so it can be arranged in large lengths without seams, and can be used at low temperatures down to -200℃. In addition, it has toughness.

This steel material is characterized by its strength and its surface shape, which has rib-shaped protrusions on its surface that form threads, so that a suitable anchorage or coupling body can be fitted.

), it is used not only for ordinary reinforcing bars but also as PC tension material.

In addition, this steel material is used, for example, as a single tension steel rod for horizontal tension members, and as a single component of a bundle of several tension members, for example, for longitudinal tension members. .

This steel material has a stress fluctuation of 0 to 30 icy/mrit.
(kg weight), 30 ky/
It shows the fatigue strength of min (weight kq).

On the other hand, if the standard stress induced by P, C, and tendons reaches 70 kg/H1j (weight kq), the fatigue strength is 24 kq/rnijt (weight ky).
becomes.

Regarding this difference in amplitude, ordinary reinforcing bars are placed in the outer part of the reinforced concrete plate where the maximum stress vibration occurs, whereas PC tension members are placed in the inner part of the plate where the stress vibration is relatively reduced. You can deal with it by being exposed to it.

The transverse watertight bulkhead 12 in the region of the tank spaces 5 and 6 on both sides is designed as a double arched or spherical shell.

It is connected at its outer edge to the enclosure of the respective tank space.

In the drawing a tanker suitable for transporting liquefied gases is shown.

For this purpose, the tank spaces 5 and 6 on both sides have a transverse waterproof bulkhead 12 formed as a spherical shell inside.
Insulating material 13 is provided on both sides.

(FIG. 3) The insulation material 13 is advantageously formed from layered polyurethane foam.

A layer made of, for example, epoxy resin that prevents vapor from penetrating is provided between the concrete surface of the partition wall 12 and the insulating material 130.

That is, the insulating material 13 functions as heat insulation, and the epoxy resin functions as insulation.

The hull 1 is formed into a streamlined shape.

The stern is provided with a space 14 for storing a propulsion machine 15 and a device for keeping it at a low temperature, as well as a propulsion screw 16 and a rudder 17.

A normal type upper deck structure 18 is provided on the deck 4,
This, like the supply and removal pipes for the tank space shown in FIG. 1, is not fundamentally relevant to the invention and therefore does not require a detailed explanation.

The plates forming the deck 4 are provided with widenings 4' directed to both sides, which are supported by the curved outer wall side plates 2 by oblique walls 13.

The lateral protrusion length of the widened portion 41 increases the effective cross-sectional area of the deck 4.

That is, the effective transverse cross-sectional area of the deck 4 is designed to be smaller than the effective transverse cross-sectional area of the bottom surface 3 in this type of hull for the sake of buoyancy stability.

Therefore, by making the effective transverse cross-sectional area of the deck 4 and the widened portion 4' equal to the effective cross-sectional area of the bottom surface 3, the resistance moment against bending on the deck 4 side and the bottom surface 3 side of the cross section shown in FIG. be equal.

The installation of this diagonal wall creates an additional approximately triangular tank space 20 in cross section, which can be used, for example, for ballast.

[Brief explanation of the drawing]

FIG. 1 shows a tanker according to the invention partially cut away and seen from above, FIG. 2 shows a longitudinal section of the tanker along its central longitudinal axis, and FIG. This is a horizontal section taken slightly above the line, and FIG. 4 shows the cross section on a larger scale. Codes in the diagram: 1...Hull, 2...Outer wall side plate, 3...Bottom plate, 4...Deck, 4'...
... widened part, 5, 6... outer tank space, ? ...Ballast water storage space, 8...
... Tank space for fuel, 9 ... Separation wall for storage space 7, 10 ... Transverse waterproof bulkhead (of space 7), 11 ... Auxiliary material, 12 ......Cross waterproof bulkhead (tank spaces 5 and 6), 13...
Insulating material, 14... Storage space for propulsion machine, 15.
... Propulsion machine, 16 ... Propulsion screw, 17 ... Rudder, 18 ... Upper deck structure,
19... Diagonal wall of widening section 4'.

Claims (1)

[Claims] 1. A one-piece hull made of reinforced concrete IJ, especially for transporting liquefied gas, with a space 7 in the center in the cross section of the hull.
It is divided into two spaces 5 and 6 which are arranged side by side on both sides, and extend in the longitudinal direction.
0.12, and the outer wall side plates 2, 2 of said two spaces 5, 6 are continuous with the deck 4 and the bottom plate 3, (a) the deck 4, the bottom plate 3 and the bottom plate of solid plates; The cross-sectional shape of the outer shell plate of the hull 1 consisting of the outer wall side plate 2 is such that the hoop of the outer wall side plate 2 continuously transitions to the deck 4 and the bottom plate 3 in a gentle curve with no corners, and it is difficult to avoid wave motion. The outer shell plate is formed so that the bending moment that it receives from the lateral direction of the hull due to cargo is as small as possible during use, and the outer shell plate of the hull 1 is reinforced in the lateral direction with reinforcing steel and prestressed tension material. is added, (b)
Furthermore, the outer shell plate is reinforced in the longitudinal direction with reinforcing bars and prestressed tension members, and the prestress in the longitudinal direction is designed so that the maximum positive and negative bending moments received from waves and loads are approximately equal in size during use. A tanker characterized by: 2. The tanker according to claim 1, wherein the plate constituting the deck 4 extends laterally as a widened portion 4' beyond a position where the plate constituting the deck 4 is substantially tangentially joined to the outer wall side plate 2. 3. The tanker according to claim 2, wherein the widened portion 4' is supported on the outer wall side plate 2, and an additional tank space 20 is formed on the lower surface of the widened portion 4'. 4. The tanker according to any one of claims 1 to 3, wherein the transverse waterproof bulkhead 12 is formed in the shape of an arch with a double curved spherical surface. 5. In order to transport a low-temperature liquid, for example a liquefied gas, an insulating material 13 against the permeation of cold air is provided on the inside of the walls 2 and 8 that partition the outer tanks 5 and 6, and on both sides of the transverse waterproof bulkhead 12. A tanker according to any one of claims 1 to 4.