JPH0126953B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a prestressed concrete tank for storing liquids such as water, petroleum, or low-temperature liquefied gas.

Generally, this type of tank has a dome roof 1 and side walls 2.
It has a flat-bottom cylindrical shape consisting of a bottom plate 3 and a bottom plate 3, and the connecting portion between the side wall 2 and the bottom plate 3 has a structure such as a sliding type, a hinge type, a fixed type, etc. depending on the purpose and scale.

In the sliding type structure, as shown in Fig. 2, the side wall 2 and the bottom plate 3 are completely insulated, and the side wall 2 can be freely displaced toward the center in response to prestress and water pressure in the circumferential direction. It has the advantage of being able to apply complete prestress in the circumferential direction and not creating a bending moment in the vertical direction, but it is extremely difficult to maintain liquid tightness over a long period of time. .

In the hinge type structure, as shown in FIG. 3, the side wall 2 and the bottom plate 3 are hinged,
Although no vertical bending moment occurs at the bottom end of the side wall, a larger bending moment than other methods occurs at the middle part of the side wall, and a large amount of prestressing steel is required in the vertical direction. In addition, since the displacement of the lower end of the side wall toward the center is restricted, it is not possible to introduce compressive force due to prestress in the same circumferential direction to the lower part of the side wall as in the upper part, and cracks may occur due to drying shrinkage or temperature changes. Easy to do. Furthermore, it is also difficult to ensure liquid tightness with this method.

In addition, in the fixed type structure, as shown in Fig. 4, the side wall 2 and the bottom plate 3 are rigidly connected, and the liquid tightness is the best, but due to circumferential prestress and hydraulic pressure, the lower end of the side wall A large vertical bending moment occurs. Therefore, a large amount of prestressing steel is required in the vertical direction. Further, since the displacement of the lower end of the side wall toward the center is restricted, it is not possible to introduce compressive force due to prestress in the circumferential direction to the lower part of the side wall, as in the case of the hinge method.

The present invention was proposed in order to solve these problems, and the corner portion that connects the tank side wall and the bottom plate is made into a continuous curved shell structure, and the corner part that connects the tank side wall and the bottom plate is made into a continuous curved shell structure, and the corner part that connects the tank side wall and the bottom plate is made to have a continuous curved shell structure, and the corner part that connects the tank side wall and the bottom plate is made to have a continuous curved shell structure. The present invention relates to a prestressed concrete tank characterized by having a horizontally movable sliding layer provided therebetween.

In the prestressed concrete tank according to the present invention, as described above, the corner portion that connects the tank side wall and the bottom plate is changed from the orthogonal structure as in the conventional system to a continuous curved shell structure for smooth stress transmission, and By providing a horizontally movable sliding layer between the side wall and the bottom surface of the bottom plate located between the corner part and the foundation plate, the horizontal displacement of the corner part is not restricted, and the surface The generation of outward secondary stress can be suppressed to a small level.

In addition, by creating a curved shell structure at the lower corner of the side wall to facilitate deformation in the radial direction, sufficient compressive force can be introduced in the circumferential direction by prestressing. This can prevent cracks from occurring due to shrinkage or temperature changes.

Furthermore, if necessary, the axial prestressing steel materials that were placed separately on the side walls and bottom plate can be made into continuous and identical pieces, thereby saving on the prestressing steel material fixing devices.

As described above, according to the present invention, an economical prestressed tank with excellent liquid tightness, thin member thickness, and a small amount of prestressed steel material is provided.

The present invention will be described below with reference to the illustrated embodiments.

In FIGS. 5 and 6, 11 is the dome roof of the prestressed concrete tank, 12 is the side wall, and 13 is the bottom plate. The corner part 14 connecting the side wall 12 and the bottom plate 13 is constructed in a continuous curved shell structure. 14, the bottom plate 13, and the lower surface of the side wall 12 are installed on the base plate 15.
In addition, a PC steel material 16 is disposed in the circumferential direction on the side wall 12 and the corner portion 14 in order to cancel out the circumferential axial tensile force due to the tank internal liquid pressure, gas pressure, etc. has been introduced.
Further, if necessary, an axial prestressing steel member 16' is arranged to resist bending moments in the out-of-plane direction.

The bottom plate 13 is formed in a disk shape or a ring shape, and a sliding layer 17 is interposed between it and the base plate 15,
It is supported on the base plate 15 in a state where horizontal displacement due to external force, temperature change, etc. is not restrained in any way.

The base plate 15 directly below the side wall 12 is formed into a trapezoidal shape, and the sliding layer 1 is provided between the top surface of the base plate 15 and the bottom surface of the side wall 12.
8 is interposed, and the weight of the dome roof 11 and side wall 12 is directly transmitted to the foundation plate 15.
Therefore, the structure is configured so that horizontal displacement due to prestress, external force, temperature change, etc. is not restrained in any way. Note that a cushioning material 19 is interposed between the corner portion 14 and the base plate 15, or a space is left open to allow free deformation.

Furthermore, an uneven load acting on the entire tank, such as a horizontal force during an earthquake, is resisted by a ring-shaped horizontal movement prevention protrusion 20 protruding from the outer periphery of the foundation plate 15. In addition, when the said unbalanced load is small, it is also possible to take charge by the base plate 15 via the corner part 14 and the buffer material 18, without providing the protrusion 20 for preventing horizontal movement.

In the illustrated embodiment, as described above, the corner portion 14 connecting the side wall 12 and the bottom plate 13 is changed from the conventional orthogonal structure to a curved shell structure with smooth stress transmission, and the sliding layer 1
7 and 18, the generation of secondary stress in the out-of-plane direction can be suppressed to a small level, and as described above, the corner portion 14 has a curved shell structure. This makes deformation in the radial direction easier, and sufficient compressive force can be introduced in the circumferential direction by prestressing.

7 to 9 show another embodiment of the present invention, in which a convex shape extending radially from the center to the outer periphery is provided on the lower surface of the bottom plate 13 as a means for resisting unbalanced loads such as earthquake horizontal force. A cross-sectional shearing key 21 is provided protrudingly, and a concave groove 22 is provided on the base plate 15 in which the shearing key 21 engages, thereby making it possible to maintain a uniform axis such as prestress, tank internal liquid pressure, gas pressure, and temperature changes. Although it can freely deform in the radial direction in response to a symmetrical load, the shearing force is transmitted to the base plate 15 via the shear key 21 in response to a non-axisymmetric horizontally biased load.

Although the present invention has been described above with reference to embodiments, the present invention is not limited to such embodiments, and can be modified in various ways without departing from the spirit of the present invention.

[Brief explanation of drawings]

Fig. 1 is a longitudinal sectional front view of the left half showing an outline of a prestressed concrete tank, Figs. 2 to 4 are longitudinal sectional views showing a conventional joint structure between a side wall and a bottom plate, and Fig. 5 is a longitudinal sectional view of a conventional prestressed concrete tank according to the present invention. Vertical sectional view showing an example of a prestressed concrete tank, No. 6
The figure is an enlarged view of the main parts, Figures 7 to 9 show other embodiments of the prestressed concrete tank according to the present invention, Figure 7 is a plan view of the tank bottom, and Figure 8 is a longitudinal section of the tank bottom. 9 is a view taken along the arrow in FIG. 8. 12...Side wall, 13...Bottom plate, 14...Corner part, 15...Foundation plate, 17...Sliding layer.

Claims (1)

[Claims] 1. A prestressed rest, characterized in that the corner part that connects the tank side wall and the bottom plate has a continuous curved shell structure, and a sliding layer that is movable in the horizontal direction is provided directly below the side wall and between the bottom surface of the bottom plate and the foundation plate. concrete tank.