JPS605968A - Prestress introduction of pc slab in existing structure - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention When constructing a new structure under an existing structure, the present invention supports the existing structure with a PC slab, supports the same or C slab with cast-in-place piles, etc., and then builds a new structure. constructing a structure,
This relates to a method for introducing prestress into a PC slab, which is applied to the underbinning method using a PC slab.

Figures 1 and 2 show a conventional method of this kind, in which the PC cable (1) has to be placed, for example in the longitudinal direction, of a PC slab (3) covering the footing (2) of a conventional structure. Moreover, since the tensioning work can only be done at the ends of the PC slab (3), the following problems arise.

α) Considering the spread of prestress p, it is unlikely that sufficient prestress will be introduced into the membrane structure.
It is impossible to impart sufficient extrusion shearing resistance to the existing footing located at the end, but in order to introduce a sufficient amount, a large line end distance l is required, and the PC
The slab must be dog-tokked.

h) On the outside from the edge of the slab, the tensioning space of the PC bracket is
Step 9 is required.

C) Therefore, when constructing adjacent slabs - the other slab cannot be constructed until the tensioning force of one slab is completed.

In order to eliminate the drawbacks of ``Yariki b) C)'', PC slab (
3) Do not place the tensioned end of the PC cable (1) at the end;
As shown in the figure, the tensioned end of the PC cable (1) may be placed in a notch (4) provided on the upper surface of the middle of the KPC slab (3). However, since the PC cable (1) is wrapped and placed 7, not only does the amount of PC cable (1) increase, but also the cutout (4) creates a cutout in the cross section. The disadvantage was that the arrangement was complicated.

Note that (5) in each of the above figures is a cast-in-place pile for underbinning.

The present invention has been devised to eliminate the above-mentioned drawbacks, and involves introducing prestress into a slab surrounding the footing of an existing structure to integrate the existing structure and the slab, and then forming a PC slab. In the method of supporting the existing structure with cast-in-place piles, etc., the existing structure is characterized in that PCfJ materials are arranged in a loop so as to surround the existing structure, and the same PC steel materials are tension anchored in the middle of the slab. This relates to a method of introducing prestress into a rolled-up PC slap.

In the present invention, as described above, the prestressing steel material is arranged in a loop so as to surround the existing structure, and the prestressing steel material is tension anchored in the middle of the slab. A prestress is introduced, which increases the punching shear strength and bending resistance, which is advantageous in terms of structure.

In addition, as mentioned above, since the PC steel material is arranged in a loop shape, there is no need to tension the PC steel material at the end of the slab, and there is no need for a tensioning somise on the outside of the slab. The present invention has many advantages, such as the fact that the tensioning and anchoring of the PC steel material is carried out individually for each slab, so slabs can be constructed as desired, which is advantageous in terms of process.

The illustrated embodiments of the present invention will be described below.

Excavate the slurry section shown in O2 to the lower end of the footing of the existing structure. (See Figure 4) PC copper material α3) and reinforcing bars are arranged in the excavated area, concrete is poured, and a PC slab u4) is constructed.

At this time, the PC steel material (13) is arranged in a loop shape so as to wrap around the footinda circle, and no tension end is provided at the end of the slab. In addition, in the part located at the head of the cast-in-place pile in the slab 04), a steel pipe or the like is buried to provide an opening 0, and an intermediate movable anchor for tensioning the prestressed steel material αm is installed in the same opening (1). (See Figures 5 and 7) Next, in the opening +151, the PC steel material (13) is tensioned through the intermediate movable anchoring tool (161 12) and anchored to the slab (14). By introducing pre-stress into the existing structure, we integrated the footing (old) of the existing structure with the said Suraka 1 side [7 and cast-in-place pile 07;
4) - After taking a break from cultivation, excavation and construction of the lower part a of the same PC slab 0 a) will be carried out. (See Fig. 6) Figs. 8 to 12 show tension anchoring of a PC Confucian wood round using an intermediate movable anchoring tool fllit, and a curved anchor ( 18),
Center hole jack (2
0), connect one end of the loop-shaped PC steel material (131) to the anchoring tool (1 (9) with l'J!0211,
The other end is inserted into the same anchoring shell 0θ and each of the chairs (181 (11) and tensioned with the jack (20), and the anchoring tool (
1 (9) via a wedge (221), and ridge concrete C (is placed in the notch αm).

c in the figure! → is a sheath, (251 & 251) The tension of the PC steel material is filled with grout after anchoring.

Although the present invention has been described above with reference to embodiments, the present invention is, of course, 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]

Figure 1 is a plan view showing the construction situation using the conventional construction method, Figure 2 is a view taken along arrows -■ in Figure 1, Figure 3 is a vertical sectional view showing the construction situation using another example of the conventional construction method, and Figure 4 6 are longitudinal cross-sectional views showing steps of an embodiment of the method for introducing prestress into a slab involving an existing structure according to the present invention, FIG. 7 is a view taken along arrows ■-■ in FIG. 5, Fig. 8 is a plan view showing the tension anchoring part of the loop-shaped PC@ material, Fig. 9 is a longitudinal sectional view showing the state when the PC steel material is tension anchored by the intermediate movable anchoring device, and Fig. 10 is its plan view. , FIG. 11 is a longitudinal sectional view showing the completed state of the prestressed steel tension anchoring portion, and FIG. 12 is a plan view thereof. tI...Footing, 0th floor...PC steel, 04
)...PC slab, a...opening, (15'
)... Notch, +161... Intermediate movable anchor anchorage agent Patent attorney Okamoto Shigemon 3 persons Fig. 3 Fig. 4 Fig. 5 Fig. 6

Claims (1)

[Claims] In a construction method in which prestress is introduced into the slab surrounding the footing of the existing structure to integrate the existing remains and the slab, and then the PC slab is supported with cast-in-place piles, etc., the PC slab is placed so as to surround the existing structure. A method for introducing prestress into a PC slab involving an existing structure, characterized by distributing steel material in a loop shape and anchoring the same PC steel material tensionally in the middle of the slab.