JPH0545627Y2 - - Google Patents

Description

[Detailed explanation of the idea]

[Industrial Application Field] The present invention relates to a centrifugally formed prestressed concrete column used for foundation piles, bridge supports, building columns, etc. [Conventional technology] Columns used for foundation piles, bridge supports, etc. are steel pipe concrete columns (SC columns) made by pouring expandable concrete into steel pipes and forming them by centrifugal force.
, high-strength prestressed concrete columns (PHC columns) in which PC steel wires are buried in high-strength concrete and formed by centrifugal force, and prestressed concrete columns in which PC steel bars and deformed steel bars are buried in concrete and formed by centrifugal force. There is a concrete column (PRC column). When manufacturing SC columns, the thickness of the steel pipe can be selected as desired, and since it is made of composite material, it can be made strong, but it takes more than a month from ordering the steel pipe to delivery, making it an emergency. Not suitable for production. or,
Since the allowable stress of the steel pipe is low (2400 kg/cm ² ) and corrosion allowance must be taken into account, it is expensive and uneconomical. PHC columns have an N-M curve almost similar to SC columns, and are made mainly of PC steel wire and high-strength concrete, so they are relatively inexpensive, but they require a lot of bending when used. You cannot expect durability. In addition, PRC columns have slightly greater strength and toughness than PHC columns even though they use both PC steel bars and deformed steel bars, but since the PC steel bars break due to stress concentration, it is difficult to use deformed steel bars. However, the toughness against repeated bending stress is not sufficient. [Problems that the invention aims to solve] This invention uses commercially available steel materials that are significantly superior in toughness to conventional PHC columns and PRC columns, and
The aim is to provide prestressed concrete columns that can be used in place of SC columns, which are cheaper than columns and can be produced immediately. [Means for Solving the Problems] In order to achieve the above-mentioned purpose, the present invention is designed so that the ratio of the PC steel wire to the cross-sectional area of the concrete body is 0.6 to 0.9.
%, the ratio of the deformed steel rod is 1.0 to 6.0%, and the vertical cross-sectional area ratio in the concrete body is 0.6 to 0.9 over almost the entire length of the outer circumference of the PC steel wire and deformed steel rod arranged along the entire length in the axial direction. A reinforcing bar cage consisting of a spiral bar of ^ordinary iron wire tightly wound so as to have a strength of The outer diameter is 300~
It is made up of 1000mm high-toughness concrete columns. [Function] This proposal has the effect of changing the PC steel bar to a PC steel wire and tightly winding the helical reinforcement to obtain greater toughness than ever before. Regarding the characteristics of the PC steel bar and the PC steel wire, After making short length marks on the PC steel rod and PC steel wire at equal intervals and pulling them until they broke, the elongation of each section was examined, and the results shown in Figure 3 were obtained. As shown in Figure 3, the elongation of the section adjacent to the fracture point is small for the PC steel bar and large for the PC steel wire. This is because in the case of a PC steel bar, the elongation at the fracture point is large and protrusive, while the elongation in the adjacent areas is small, making it a concentrated type.On the other hand, in the case of a PC steel wire, the elongation in the adjacent areas is also large and has a gentle shape, so it is not a concentrated type. PC steel bars tend to undergo local elongation, and because plastic deformation does not occur until near fracture, they are susceptible to stress concentration, and it can be said that they have the disadvantage that they are weaker than PC steel wires with respect to bending and tension in concrete cracks. Next, a test specimen with a length of 8 m and an outer diameter of 400 mm was made, and a progressively increasing displacement positive/negative alternating cyclic bending test was conducted under the load span shown in Fig. 4. The result is the fifth
As shown in the figure. The test specimens shown in Table 1 were used.

〔Example〕

Table 2 shows a configuration example when the present invention is applied to a column with an outer diameter of 300 to 800 mm.
Figure 2 shows a vertical cross-sectional view and a cross-sectional view of a column with an outer diameter of 400 mm. PC steel wire 1 and deformed steel bar 2
are arranged alternately along the cylindrical surface and welded with the spiral reinforcement 3 wrapped around the outer circumference to form a reinforcing bar cage, which is centrifugally formed and cured with high temperature and high pressure steam to form a concrete body with a compressive strength of 850 kg/cm ^2. It is buried in 4. The concrete body 4 is prestressed in the axial direction by the PC steel wire 1. The deformed steel bar 2 does not necessarily extend to both ends, and both ends may be located slightly inside from the end surface of the column.

【table】

[Effect of idea]

Figure 6 shows a comparison of the N-M curves of columns with an outer diameter of 600 mm, and SC9, SC6, and SC4.5 are SC columns with steel pipe thicknesses of 9 mm, 6 mm, and 4.5 mm, respectively.
-1 and -4 are seeds according to the present invention, seeds (second
D13, D22 as deformed steel bars in the column of outer diameter 600 mm in the table
equivalent), H indicates a general PHC pillar. In both cases, the compressive strength of concrete is 850
Kg/ ^cm2 . As can be seen from this figure, compared to SC and PHC columns, the top of the mountain is flat, so when setting the short-term bending moment per column, it is possible to Since this is determined, the proposed column can be designed economically. According to the present invention, it is possible to provide a prestressed concrete column that can be used in place of a steel tube concrete column, which is cheaper than a steel tube concrete column and can be readily produced.

[Brief explanation of the drawing]

Figure 1 is a vertical cross-sectional view of a high-toughness concrete column according to the present invention, Figure 2 is a cross-sectional view of Figure 1, and Figure 3 is a cross-sectional view of a prestressed steel wire and a prestressed steel bar when they are stretched until they break. Figure 4 shows the elongation strain for each section in the length direction, Figure 4 shows the test conditions for the specimen, Figure 5
The figure shows the test results of the specimen, and Figure 6 shows the N-M curves of the proposed column, SC column, and PHC column. 1...PC steel wire, 2...deformed steel bar, 3...spiral bar, 4...concrete body.

Claims (1)

[Scope of utility model registration request] The ratio of the PC steel wire to the cross-sectional area of the concrete body is 0.6 to 0.9%, and the ratio of the deformed steel bar is 1.0 to 6.0.
%, PC steel wire and deformed steel rod arranged along the entire length in the axial direction, and ordinary iron wire tightly wound around almost the entire length of the outer circumference so that the vertical cross-sectional area ratio in the concrete body is 0.6 to 0.9%. A reinforcing bar cage consisting of spiral bars is buried in a concrete body with a compressive strength of 800 kg/cm ² or more, and the above-mentioned
High-toughness concrete columns with an outer diameter of 300 to 1000 mm prestressed by PC steel wire.