JPS5853626B2 - How to build synthetic marine structures - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a construction method for constructing composite marine structures using a combination of steel and concrete.

For example, the Purge, which is known as a floating offshore structure that houses various plant facilities such as chemical plants and power generation plants, has concrete outer panels on the sides and bottom, and a steel deck on the top. In addition, a steel internal frame for reinforcement is appropriately placed in the internal space, making it a so-called composite structure of steel and concrete.

Therefore, when constructing such a composite marine structure, the steel inner frame is assembled and arranged in the desired condition, and then concrete is successively poured around it to form a concrete outer panel. However, in this case, because the size of this type of structure itself is considerable, the concrete shell is usually constructed using the cast-in-place method at a dock or ship's slipway. For this reason, the construction work is troublesome and the construction period is long, which increases the construction cost.Moreover, it is difficult to obtain the necessary strength and watertightness for the outer panel of this type of structure. There was a problem that it was difficult to

That is, when forming the bottom concrete that constitutes the concrete outer panel, the large-scale steel internal frame described above is suspended on the forming form using some construction support jig. It is necessary to lower the inner frame and secure a space for concrete pouring under the inner frame, which is not only troublesome, but also has poor construction efficiency, and the weight of the inner frame requires a considerable amount of work to support the jig. Furthermore, there were problems in that it was complicated to put on and take off, and the construction costs were high.

In addition, with the method of using such a support jig, as the marine structure becomes larger, the overall size of the internal frame,
It was almost impossible to construct due to weight and other issues.

Furthermore, when constructing the aforementioned concrete exterior panels using the cast-in-place method, it is difficult to make the concrete homogeneous over the entire surface due to issues such as the pouring area. This is particularly noticeable when casting, since the pouring height is sufficiently high compared to the pouring area.Furthermore, when forming the bottom concrete, the internal frame and supporting jig get in the way. In terms of workability, the finished surface accuracy was poor and it was difficult to obtain homogeneous concrete.

Furthermore, the above-mentioned cast-in-place exterior panel forming work takes a long time depending on the size of the structure, and this is especially noticeable when forming the side concrete. fully occupy the
Not only did the construction cost increase, but there were also problems such as interfering with other construction work.

Furthermore, the concrete exterior panels mentioned above are generally made of prestressed concrete due to their strength issues, and with the conventional construction methods mentioned above, when prestressing is introduced, the entire structure is It is connected and resists loads as a composite structure of steel and concrete,
A considerable amount of prestress also acts on the steel members installed as the internal frame, and this introduces particularly harmful compressive stress as extra stress into the steel members installed as the internal frame. In addition, with PC steel materials for introducing the minimum necessary prestress to the concrete outer panel, it is difficult to apply the desired prestress to the concrete outer panel due to the presence of the inner frame. The drawback was that it couldn't be done.

In order to solve this problem, it is necessary to add a large amount of prestressing steel material in consideration of the presence of the internal frame, which is a steel member mentioned above, resulting in a large loss.

In addition, there are few examples of such synthetic marine structures,
Furthermore, since there are almost no full-scale large-scale structures, it is impossible to apply conventional construction methods as they are, and there is a need for a new construction method for this type of synthetic marine structure.

The present invention has been made in view of the above-mentioned circumstances, and includes a structure in which only the lower part of the steel internal frame of a synthetic marine structure is supported at regular intervals on the formwork for forming the bottom concrete, and the lower part thereof is While pouring concrete and forming the bottom concrete, the side concrete is pre-formed separately as multiple precast members, and these are integrated with the bottom concrete, and the outer part of the internal frame incorporated in this precast member is by connecting the inner frame to the lower part of the inner frame, introducing prestress into the side and bottom concrete, and then assembling the remaining inner frame to the outer and lower parts thereof. , the forming operations of the side and bottom concrete are simple, and most of the internal frames do not introduce prestressing, making it easy to obtain the desired strength and also the construction of the entire structure. To provide a method for constructing a synthetic marine structure that can shorten the construction period and reduce the construction cost.Hereinafter, the first invention will be explained in detail using embodiments shown in the drawings.

FIG. 1 shows an embodiment of a synthetic marine structure to which the construction method according to the present invention is applied. It has a steel deck 2 on its upper surface.
However, a side concrete 4 and a bottom concrete 5 each consisting of four sides are provided as a concrete outer plate 3 on the side and bottom parts, and these deck 2
In the internal space covered by the above-mentioned deck 2 and the outer panel 3, a reinforcing internal frame 6 consisting of a steel bulkhead, ribs, etc., which acts in combination with the above-mentioned deck 2, outer panel 3 and external force, is installed as appropriate. It is located.

Now, according to the present invention, when constructing the above-mentioned synthetic marine structure 1, the bottom concrete 5 is constructed by a cast-in-place method at a dock or the like, but the steel internal frame 6 is pre-constructed like the steel deck 2. The side concrete 4 is suitably made into blocks at another location, further transported and prepared in the dock, and the side concrete 4 is formed in large numbers with the same shape, size, etc. in advance as side precast members at another location called a block yard. , which are also transported to the dock and prepared.

Then, the bottom concrete 5 is formed by sequentially combining the deck 2, internal frame 6, and side concrete 4 that have been made into blocks as described above.The construction method is described below using Figures 2 to 6. Explain in detail.

Fig. 2 and Fig. 6 [I] show the case where a pouring space 7 for bottom concrete molding is secured under the internal frame 6. What should be noted here is not the entire internal frame 6, but the underside of the internal frame 6. Only the portions 8 are supported on the molding frame 9 at regular intervals.

That is, the lattice blocks 8a constituting the lower part 8 of the internal frame 6 are sequentially arranged on the support stands 10 arranged on the formwork 9 starting from the center one, and the respective joints are welded and connected. Meanwhile, as shown in FIGS. 3 and 6 (ID), concrete is successively poured into the pouring space 7 on the lower side, and the corresponding bottom concrete 5 is formed.

At this time, the support stand 10 may have a simple structure since the weight of the lattice block 8a to be supported is sufficiently small, and may also be provided with a height adjustment function.

Further, the support stand 10 is sequentially removed after the poured concrete hardens and obtains the desired strength.

Note that the work of pouring concrete below the lower part 8 of the internal frame 6 described above can be easily performed without causing any obstruction due to the shape, height, etc. of the lower part 8. On the other hand, compaction can be easily performed, and the surface accuracy of the finished product can be greatly improved.

FIGS. 4a and 4b show a side precast member 11 formed by dividing and molding this into a plurality of parts in order to form the side concrete 4.
A bending part 11a, which constitutes a part of the bottom concrete 5, is integrally formed on the lower side of the side precast material 11 so that it can stand on its own. The outer portion 2a of the deck 2 is connected to the upper end portion of the portion 12 in advance.

The side precast member 11 has better homogeneity than cast-in-place side concrete, and can be expected to have sufficient strength.

In addition, since the outer part 12 of the inner frame 6 and the outer part 2a of the deck 2 are joined to the inside of the side precast member 11 in advance, when the remaining inner frame 6 and deck 2 are welded and assembled, Concrete is not affected by heat and its quality can be improved.

In this case, the construction period can be shortened by performing the forming and assembling work of the side precast member 11 at the same time as the forming work of the lower part 8 of the internal frame 6 and the bottom concrete 5 below it. .

Side precast part 1 prepared as described above
1 is integrated with the lower part 8 of the internal frame 6 and the bottom concrete 5 in the following manner.

That is, the lattice block 8b disposed on the side of the lower part 8 of the internal frame 6 is supported on the support stand 10 (see FIG. 6 CI), and the side precast member is further placed on the side thereof. 11 are erected one after another at predetermined intervals, the joints between the lattice blocks 8b and the outer part 12 of the internal frame on the side precast member 11 side are welded together, and the support base 10 on the lower side is removed. See Figure 6 (IV)].

Then, in that state, each side precast member 11
Concrete is cast in the gaps between the blocks to form side concrete 4, and concrete is cast in the casting spaces 13 below the lattice blocks 8b to form bottom concrete corresponding to the central lattice blocks 8a. 5 and the bent portions 11a of the side precast members 11 are successively integrated.

This state is shown in FIGS. 5 and 6 [■].

Then, in the present invention, the side and bottom concrete 45 is formed over the entire structure by the method described above, and when the concrete has hardened and achieved the desired strength, prestress is introduced into the side and bottom concrete 45. There is.

At this time, only the lower part 8 and the outer part 12, which constitute the inner frame 6, are joined to the side and bottom concrete 4, 5, and the prestress is introduced into the concrete very effectively. Therefore, it is possible to obtain the desired degree of prestressing stress without using an unnecessarily large amount of prestressing steel, and unnecessary stress is not applied to the majority of the internal frame 6. .

Here, as a specific means for introducing prestress to the side and bottom concrete 4.5 mentioned above, a well-known method called the post-tensioning method, which has been conventionally adopted in bridges, etc. It is recommended to use the prestress introduction method.

To briefly explain this method, a thin steel pipe called a sheath is embedded in concrete in advance, and after the concrete hardens, a prestressing steel material is inserted into the steel pipe, and tension is applied to the prestressed steel material, which acts as a reaction force on the concrete through a bearing plate. This method applies compressive force to the

Then, after introducing the prestress mentioned above, the CVI in Figure 6
), the remaining internal frame 6a is assembled by sequentially welding the remaining internal frame 6a to its lower part 8 and external part 12 block by block, and the remaining deck 2 is further fixed, as shown in FIG. The synthetic marine structure 1 is completed.

In the method for constructing a synthetic marine structure according to the present invention as described above, since only the lower part 8 of the internal frame 6 is supported on the formwork 9 when forming the bottom concrete 5, the construction is difficult. This is extremely easy to carry out, and this ensures that when introducing prestress into the side and bottom concrete 4, 5, no unnecessary stress is applied to the majority of the internal frame 6, and the desired strength is maintained in the side and bottom concrete. It has an excellent effect in that it can be applied to concrete 45.

In addition, in the above-mentioned embodiment, the construction method according to the present invention is
For example, we have explained the case where it is applied to a rectangular parallelepiped-shaped synthetic marine structure such as a purge, but it is not limited to this, and can be applied to structures with various shapes, and it can be applied to structures according to the shape. It can be changed as appropriate.

As explained above, in the method for constructing a synthetic marine structure according to the present invention, when forming the bottom concrete, only the lower part of the internal frame to be joined to this is supported by supports arranged on the formwork. Since the internal frame is supported at regular intervals and concrete is poured in sequence in that state, there is no need for large-scale support jigs that were conventionally used to support the entire internal frame, and a simple support stand can be used instead. Moreover, not only the forming operation is simple, but also the compaction of concrete is easy, and the homogeneity of the bottom concrete can be expected.

Further, according to the present invention, the side concrete is constituted by a plurality of side precast members, and the outer part of the internal frame and a part of the bottom concrete are integrally provided on the side precast members. It is easy to integrate the bottom concrete and the bottom concrete, which simplifies the construction of the entire structure.
It has the advantage of shortening the construction period for docks, etc., and significantly reducing construction costs.

Furthermore, in the construction method according to the present invention, prestress is introduced with only the outer and lower parts of the internal frame joined to the side and bottom concrete, so prestress is applied to the internal frame side as in the conventional method. There are no problems such as adverse effects caused by the introduction into the concrete, and there are effects such as the fact that it is introduced into the concrete very effectively and it becomes easy to obtain the desired strength.

According to the present invention, compared to the conventional case where prestress is introduced in a state where the entire internal frame including the steel deck, steel bulkhead, etc. is assembled and joined to the side and bottom concrete, Even if the cross-sectional configuration and external force conditions of this composite structure are the same, the prestress does not need to act over the entire internal frame, but can be efficiently introduced into the concrete skin, allowing only the necessary prestress to be applied. There is an advantage that only the amount of PC steel material for introducing stress is required, and as a result, the amount of PC steel material can be reduced.

[Brief explanation of drawings]

The figures show an embodiment of the method for constructing a synthetic marine structure according to the present invention, and FIG. 1 is a perspective view schematically showing a synthetic marine structure for carrying out the method, and FIGS. 2, 3, and 5. 4 is a schematic perspective view for explaining the construction order, FIGS. 4a and 4b are perspective views for explaining the side precast members used for this, and FIG. be. 1...Synthetic marine structure, 2...Steel deck, 3...Concrete outer plate, 4...
・Side concrete, 5...Bottom concrete, 6...Steel internal frame, 7...Pouring space, 8...Lower side part, 9・・・・・・Formwork,
10...Support stand, 11...Side precast member, 12...Outside part, 13...
・Pouring space.

Claims (1)

[Claims] 1. A method of constructing a composite marine structure having a concrete outer panel and a steel inner frame appropriately arranged inside the structure, wherein only the lower part constituting the inner frame is The bottom concrete is formed by sequentially assembling and arranging them on support stands supported at regular intervals on the formwork for forming the bottom concrete that constitutes the outer panel, and pouring concrete in the pouring space below the bottom concrete. A side precast member formed by integrally combining a part of the side concrete constituting the outer panel and a corresponding part of the outer part and bottom concrete of the inner frame is formed by forming the inner frame. It is erected on the side of the lower part of the frame with a predetermined gap, and concrete is poured into the gap between these side precast members to integrate the side concrete, and the inside of each side precast member is a step of integrating the outer part of the frame and a part of the bottom concrete into the lower part of the inner frame and the bottom concrete below the inner frame, respectively; and the step of joining only the outer part and the lower part of the inner frame. a step of introducing prestress into the side and bottom concrete, and a step of sequentially assembling and connecting the remaining inner frame to the outer and lower parts of the inner frame joined to the side and bottom concrete; A method of constructing a synthetic marine structure characterized by comprising: