JPS58206910A - Method for measuring deformation of reinforced concrete or concrete structure and average strain gage used in said method - Google Patents

Abstract

PURPOSE:To measure deformation with high accuracy by enabling the measurement of data as lines enclosing the range of a measuring object with substantially no discontinuity. CONSTITUTION:A section 71 to be measured is segmented by 1- several prescribed lengths 72, 73-, and average strain gages 74, 75- each having the instrument length equal to a prescribed length by each of said segments. Both end parts of said gages 74, 75- are connected in a longitudinal array by using connecting fittings 76 to the length conforming to the above-described section to be measured. Concrete sticking pieces 77 are mounted to both end parts in the section to be measured. A series of the gages 74, 75- which are connected of plural pieces in the above-mentioned way are provided respectively in combination with a pair of strain measuring lines L1, L2. If such measurement constitution is adopted, the specific data which is the data of an extremely local place is leveled off in each segment and has the virtually negligible values; therefore, the processing as the data extremely useful in data analysis is made possible.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for measuring deformation of reinforced concrete (including steel-framed concrete) or concrete structures (hereinafter referred to as "deformation") and an average strain meter that is used directly in implementing the measuring method.

Conventionally, when measuring deformation of concrete structures, etc.,
Depending on the item to be measured, reinforcing bar gauges, strain gauges, fixed inclinometers, etc. may be buried inside the concrete structure, etc.
A method is used in which a guide tube with an open top end is buried in advance, and an insertion type inclinometer is inserted afterwards, and deformation is measured using these instruments. Among them, the reinforcing bar meter detects the stress applied to the reinforcing bars. However, it is considered to be a very useful buried design tool because it can calculate the axial force and bending moment acting on the concrete structure, etc. from the reinforcing steel stress, as well as calculate the approximate angle of inclination and displacement in the direction perpendicular to the axial direction. Ta.

However, with the exception of the insertion type inclinometer, the measurement data obtained from these buried design devices do not seamlessly cover the measurement target range, but can be considered to be point data for each buried location. Even if there is a unique situation in the vicinity, such as minute voids, cracks, or uneven material that does not affect the strength of the concrete structure mentioned above, measurement data can be obtained from the buried design equipment at that location. becomes anomalous data.

In other words, the d strain that occurs in reinforcing bars, etc. is closely related to cracks in concrete, etc., and while large strains occur at the location of cracks, etc., they occur in reinforcing bars, etc. a little further away from the location of cracks, etc. Strain is generally small, and measuring the behavior of a member under such conditions in the form of a so-called point cannot ignore the risk of obtaining anomalous data. In order to determine whether or not the obtained data contained unique data and to obtain the truly necessary data, it was necessary to bury instruments with far more measurement points than necessary for data analysis. . This means that
This not only increases the cost of procuring a large number of instruments, but also increases the cost of burying, measuring, and analyzing, leading to a significant increase in the total cost required for measurements.

The present invention was made in view of the above-mentioned shortcomings in the conventional method for measuring deformation of concrete structures, etc., and the instruments used in the method, and its objects are as follows.

The first object of the present invention is to provide deformation of concrete structures, etc., which has a slight effect on measurement data due to minute voids, cracks, or uneven parts of the material that do not affect the strength of the concrete structures, etc. The objective is to provide a measurement method.

A second object of the present invention is to provide a method for measuring deformation of concrete structures, etc., which can obtain measurement data that covers the measurement target range almost seamlessly.

A third object of the present invention is to provide a method for measuring deformation of concrete structures, etc., which can reduce the total cost required for measurement. .

The fourth object of the present invention is to make the length of the measurement instrument a predetermined length necessary for analysis, and by using this, an average strain meter that can achieve the first object of the present invention. It is about providing.

A fifth object of the present invention is to connect both ends to other mean generating strain gauges of the same type, to connect a plurality of them in tandem, and to have a length that covers the measurement target section. A second object of the present invention is to provide an average strain meter that can achieve the object.

A sixth object of the present invention is to provide an average strain meter suitable as an on-site buried design device that has a simple structure, is hard to break, and is easy to bury.

The seventh object of the present invention is to obtain calibration data easily at low cost.
The object of the present invention is to provide an average strain meter suitable for supplying in large quantities.

That is, according to the method for measuring concrete structures, etc. according to the present invention, one or more pairs of strain measurement lines are set within a reinforced concrete or concrete structure at a certain distance apart in the bending direction, and Divide the measurement target section into one or several predetermined lengths, calculate the average strain for each of the sections and for each strain measurement line, and calculate the strain corresponding to each of the sections thus obtained. The first to third objectives can be achieved by measuring the deformation of reinforced concrete or concrete structures based on the average strain of .

Further, the average strain meter according to the present invention is an average strain meter used for measuring deformation of reinforced concrete or concrete structures, and has a bar shape with a predetermined length as a whole, and has connecting parts at both ends. By providing a concrete adhering part which doubles as a concrete adhering part, providing a concrete non-adhering part treated to prevent concrete from adhering to the part outside this concrete adhering part μ, and providing a strain detector inside the central part, the above-mentioned Able to achieve objectives 4 to 7.

Hereinafter, the present invention will be explained in detail using the drawings.

FIG. 1 is a front view showing the external configuration of an embodiment of the average strain meter according to the present invention. In the figure, the average strain meter has a predetermined length l! which is necessary for analysis. (instrument length) (in this embodiment, a processed steel pipe is used), and there are concrete attachment parts 3 and 4 that also serve as connections at both ends, and strain detection inside the central part 5. vessel(
A strain gauge) 6 is provided, and the concrete attachment part 3,
Concrete non-adhesive parts 7 are provided in areas other than 4, which are treated to prevent concrete from adhering, and the strain detection output of the strain detector 6 is configured so that it can be led out to the outside through an output cable 8. . Although this embodiment shows an example in which a heat shrink tube 9 is attached to the concrete non-adhesive portion 7, a concrete mold release agent may be applied thereto. In addition, concrete adhesion parts 3 and 4
For example, since the concrete adhesion force is weak if it is a pipe, it is desirable to knurl the surface or wrap a thin wire in a spiral and fix it by welding or brazing. The connecting parts 1 and 2 are threaded.

FIGS. 2(a) and 2(b) are a front view and a side view showing an example of the connecting fitting for connecting the average strain gauges of the above-mentioned embodiment. 11 is knurled to improve concrete adhesion, is provided with a fixing screw 12 that can protrude inward from the outer periphery, and is provided with a connecting screw portion 13 on the inner periphery. Screw the threaded connection part 1 or 2 of the average strain meter from one side to the middle part into the connection thread part 13 of this connection fitting, and then screw the connection part 1 or 2 of the other average strain meter to the other side. Connect the average strain gauges by screwing from the sides to the middle. After that, tighten the fixing screw 12. The average strain gauges are reliably connected to each other via this connecting fitting. Similarly, by connecting other average strain gauges in series one after another, a length suitable for the measurement target section can be obtained.

FIG. 3 is a front view showing an example of a concrete-attached piece, and the concrete-attached parts 1 to 4 on the surface thereof are similar to the concrete-attached parts 1 to 4 which also serve as connection parts in the embodiment of FIG.
6 and a connecting threaded portion 17 are formed.

The purpose of using this concrete-attached piece is that since the concrete-attached parts 3 and 4 in the example shown in Fig. 1 are half the length required in the design, the adhesion length is insufficient at both ends of the measurement target section. By attaching this concrete adhesion piece to the concrete via the above-mentioned connecting fitting, a predetermined adhesion flame is ensured.

FIGS. 4(a) and 4(b) are an enlarged cross-sectional view of the central part of the embodiment shown in FIG. 1 and a sectional view taken along the line A-A in FIG. is marked with the same number.

In FIGS. 4(a) and 4(b), pipe 21 and pipe n
are connected by screws, and their abutting portions 24 are integrated by welding. The inner diameter of the part of the central part 5 to which the strain detector 6 is bonded is thicker than the inner diameter of other parts.
In this embodiment, the strain detector 6 is ground so that the thickness of the bonded portion is half the thickness of the other portions. The output cable 8 is made by drilling a hole in a part of the pipe B, inserting it into the pipe N through the hole, and connecting it to the strain detector 6 in a predetermined manner. Filled into the pipe. The heat shrink tube 9 is attached to the surface of the pipe as described above. The strain detector 6 is normally used as shown in Fig. 4 (
As shown in a), it is constructed with two strain gauges, one of which is an axial gauge (active gauge) and the other axis is a circumferential gauge (dummy gauge). As shown in FIG. 4(b), a pair of strain detectors 6, each made up of two strain gauges, are placed on the inner wall surface of the central part of the pipe, facing each other with an angular interval of 180°. (Group) Attached by means such as gluing.

FIG. 5 is a front view showing the external configuration of another embodiment of the average strain meter according to the present invention. In this example, the first
This embodiment differs from the first illustrated embodiment in that the illustrated embodiment does not have a concrete attachment section 3.4, and a reinforcing bar attached thereto is used as the concrete attachment section.

That is, the connection parts 31, 32, in the embodiment shown in FIG.
Center part A, strain detector (strain gauge) 36. Concrete non-adhesive area 37. The output cable A and the heat-shrinkable tube 39 are numbered 1 and 2 in the embodiment shown in the first figure, respectively.
, 5, 6, 7, 8.9.

Figures 6 and (b) are a front view and a side view showing other examples of the connecting fittings for connecting the average strain gauges of the embodiment shown in Figure 5, and what is the connecting fitting shown in Figure 2? , knurled surface 41. Fixing screw 42. The connection threaded portion 43 has legs 44 on the outer peripheral surface.
is provided protrudingly, and the tip end 45 of the leg is an arc-shaped attachment part 4 to the attached reinforcing bar with a radius of curvature approximately corresponding to the radius of the attached reinforcing bar.
The difference is that 5 is formed. Through this connection fitting, the fifth
After the average strain gauges shown in the figure are connected one after another in a column, the mounting portions 45 of the legs 44 of the respective connecting fittings and the attached reinforcing bars are fixed by welding.

FIG. 7 is a circuit diagram showing an example of the electrical configuration of the strain detector 6 of the embodiment shown in FIG. 1 (the same applies to FIG. 4).

As shown in Fig. 4, the strain detector 6 usually consists of a set of two strain gauges with two axes, one of which is an axial gauge (active gauge) and the other axis is a circumferential gauge. It consists of a direction gauge (dummy gauge). In this embodiment, the active gauges are A, , A, and the dummy gauge D.

D shows an example in which a Wheatstone bridge is configured. In the figure, when a bridge power supply voltage is applied between the input terminals (11 and 131), a strain output (voltage change, hereinafter the same) proportional to the average strain is obtained between the output terminals +2+ - (41).Now, the axial strain is εa9 If the strain in the circumferential direction is εd, the resulting strain output 6 is ε-2(εa-εd) (1).Here, if the Poisson's ratio of the pipe material is -03, then εd- -0.3ε8 ・・
(2), so equation (1) becomes ε-26εa (3). Furthermore, in the case of the embodiment shown in Figure 4, the pipe wall thickness of the part 5 to which the strain gauge 6 is bonded is half the pipe wall thickness of the other parts, so if the average strain is εA, then ga force 2CA...・・・・・・(
4), so the strain output ε is ε−52ε
A, and a strain output approximately five times the average strain can be obtained.

By the way, the two biaxial gauges A, D of the strain detector 6
, and A, , D, respectively, are considered as single strain detectors 51, 52, in pairs in the bending direction, i.e.
If they are arranged on the inner wall surface of the central part 5 of the cylindrical pipe so as to face each other at an angular interval of 180° and have an electrical configuration as shown in FIG. Since a strain output proportional to the bending moment occurring in the average strain meter can be obtained, an average strain meter with such a configuration is effective when buried in a concrete structure with a relatively large bending moment.

Furthermore, although not shown in the figure, strain detectors 51 and 52 are placed on the same circumference as the strain detectors 51 and 52 at an angular interval of 90°.
If two strain detectors equivalent to 51 are attached and the electrical configuration is similar to that shown in FIG. 8, the strain detectors 51,
The strain output obtained from 52 is a strain proportional to the bending moment in the perpendicular direction, and by combining these two outputs, the average magnitude and direction of the bending moment occurring in the strain meter can be determined.

FIG. 9 is a circuit diagram in which the strain detectors 51 and 52 are separated in terms of circuit and their wiring can be selected. For example, the input terminal (11-(]+', +3l-(3γ By short-circuiting, the circuit configuration shown in Fig. 7 is obtained, and by short-circuiting the input terminals it) - (3Y, (31-(+)'), the circuit configuration shown in Fig. 8 is obtained. is inserted, and the average strain output and bending moment output can be obtained by switching them.

Figure 1O (a) is an explanatory diagram showing the inside of a reinforced concrete structure, where 61 is a reinforcing bar and 62 is a concrete structure, in particular a state in which a void 63 is formed in a part of the concrete attached to the reinforcing bar. It shows.

Figure 10 (bl) shows a stress distribution diagram of the buried reinforcing bars 61 when a tensile force is applied to the reinforced concrete structure shown in Figure 10 (a).
3 is not present, the reinforcing bar stress is almost uniform, but the reinforcing bar stress is slightly lower near the gap 63, and a very large reinforcing bar stress 66 occurs at the gap 63. Generally, when setting a location for installing a buried instrument, the purpose is not to obtain specific data, but to give the instrument a certain range of application represented by the data obtained from that instrument.

However, if there is a possibility that an instrument for detecting reinforcing steel stress (for example, the stress detection part of a reinforcing bar needle) is buried in this gap 63, the output of that instrument will exceed the applicable range of the instrument. Is it normal as representative data?
It is necessary to determine whether the data is unique due to voids, etc. Therefore, in the past, it was necessary to bury more instruments than are necessary for analysis and overlap the applicable range of data obtained from each instrument in order to eliminate abnormal or unusual data. It was accompanied by various drawbacks.

Therefore, the method for measuring deformation of concrete structures, etc. according to the present invention will be described in detail below.

Figures 11 and 12 are the first and fifth illustrations, respectively.
An example of implementing the deformation measuring method using the illustrated average strain meter will be described.

To conceptually explain the measuring method of the present invention with reference to FIG. 11, one or more pairs (one pair in the illustrated case) are placed inside a concrete structure, etc. (not shown) at a certain distance apart in the planned bending direction. Strain measurement line L, , L,...
... is set over the measurement target section 71, and
The measurement target section 71 has one or more predetermined lengths 72, 7.
3..., and the average strain is determined for each of the sections and for each of the measurement lines L, L, L,.... From the series of average strains thus obtained, first, the average axial stress and average axial force are determined by calculation (or by arithmetic processing by an arithmetic circuit). Furthermore, one or more pairs of strain measurement lines L, , L2, etc. are provided in the bending direction, and the average strain of the pair in the bending direction for each section is determined. By calculating the average bending moment (or bending stress) for each section from the average strain, it is possible to determine the deformation of the structure, which is important in deformation measurement, such as the inclination angle and displacement in the direction perpendicular to the axis (strain measurement line).

Next, the implementation procedure of the method for measuring deformation of concrete structures, etc. of the present invention when the above-described average strain meter according to the present invention is directly used will be explained with reference to FIGS. 7 and 8.

The measurement target sections 71 and 81 are set to one or more predetermined lengths (corresponding to the instrument length l in Figs. 1 and 5) 72°73...
...; 82, 83, . . ., and one average strain meter for each of these sections, each having an instrument length equal to the predetermined length, 74, 75, . . .; 84, 85, .・
. . , and the average strain gauges 74, 75.
...; Both ends of 84, 85... are connected in tandem using the connecting fittings 76 shown in FIG. 2 and the connecting fittings 86 shown in FIG. The length shall be commensurate with the area to be measured. Furthermore, concrete adhesion pieces 77 and 87 are attached to both ends of the section to be measured.

In addition, a series of average strain gauges 74, 75, .
They are installed on the paired strain measurement lines L, , and L, respectively.

In the embodiment shown in FIG. 12, the average strain meter 8
The figure shows an example in which only one set of 4, 85, .・18 on the inner wall surface of the center part of 85
The average strain is obtained by attaching a plurality of pairs of strain detectors 6 (or 36, 51, 52) at different positions to each pair with an angular interval of 0°, and furthermore, to each of these pairs by adhesive or other means. A total of 84, 85, etc. shall be used. Then, such average strain gauges 84, 85
Each pair of strain detectors is disposed in correspondence with one or more pairs of strain measurement lines.

By arranging them in this way, the strain detectors are arranged in pairs at positions separated by a certain distance even if they are a series of average strain gauges, so the embodiment shown in FIG. can have similar functionality. Therefore,
As mentioned above, not only the average strain for each section, but also the average bending moment (or bending stress) for each section can be calculated (or calculated by a calculator), and furthermore, the inclination angle and axis Deformation of concrete structures, such as displacement in the right angle direction, can be measured.

When measuring the deformation of concrete structures, if the measurement method described above is used, the unique data, which is data from very localized areas, will be equalized within each category and become almost negligible values. It becomes possible to process the data as extremely effective data for data analysis.

Furthermore, by calculating this average strain data so that it is continuous over the measurement target section, it is possible to obtain data as an almost unbroken line that covers the entire measurement target section.Based on this data, concrete When analyzing the deformation of a structure, it is possible to obtain results closer to the true value than conventional analysis using point data.

It should be noted that the present invention is not limited to the embodiments described above and shown in the drawings, but can be implemented in various modifications.

For example, the concrete attachment part can be in the form of a flange or a deep groove.

In addition, the strain detector 5 can be used with the circuit configuration shown in FIGS. 8 and 9.
1 and 52 form a Wheatstone bridge (by increasing the number of strain gauges 6 shown in Figure 4), and by combining them, twice the strain output can be obtained. I can do it.

Furthermore, although an example has been shown in which the connecting fittings 76 and 86 are configured separately from the average strain gauge, they can also be integrated with the average strain gauge.

As detailed above, according to the method for measuring deformation of concrete structures, etc. of the present invention, peculiar data due to minute voids, cracks, etc. that do not affect the strength of concrete structures, etc. are excluded, and the measurement It is possible to measure linear data (average strain, bending moment, etc.) that covers the target area almost seamlessly, and based on this data, it is possible to measure the deformation of concrete structures with high accuracy, and the total cost required for this measurement. can be reduced compared to conventional methods.

Further, according to the average strain meter of the present invention, the length of the measuring instrument can be set to a predetermined length required for analysis, and both ends can be connected to other strain gauges of the same type, and a plurality of strain meters can be connected in tandem. They can be connected in a shape with a length that covers the measurement target section, and the average strain for each section can be accurately detected. Therefore, it can be used to implement the method for measuring deformation of concrete structures, etc. of the present invention, and thereby,
This makes it possible to eliminate singular data and measure data as an almost unbroken line. Moreover, the configuration is very simple,
It is possible to provide an average strain meter that is suitable as an on-site buried design device that is hard to break and easy to bury, and that is inexpensive, easy to obtain calibration data, and suitable for supplying in large quantities.

[Brief explanation of drawings]

FIG. 1 is a front view showing the external configuration of one embodiment of the average strain meter according to the present invention, and FIGS. 2 (a) and (b) show connections for connecting the average strain meters of the same embodiment. FIG. 3 is a front view showing an example of a concrete-attached piece; FIGS. 4(a) and (b) are an enlarged cross-sectional view of the central part of the embodiment shown in FIG. Same figure A
- A sectional view taken along the line A; FIG. 5 is a front view showing the external configuration of another embodiment of the average strain meter according to the present invention; FIGS. 6(a) and (b) are the embodiment shown in FIG. 5; FIG. 7 is a front view and side view showing an example of a connecting fitting for connecting the average strain gauges of FIG. The figure shows a circuit diagram for obtaining a bending moment output, Figure 9 is a circuit diagram that can be switched to either the circuit configuration shown in Figure 7 or Figure 8, and Figures 10 (a) and (b) are circuit diagrams of reinforced concrete. Explanatory diagram showing the inside and reinforcing bar stress diagram, Figure 11 and Figure 1
FIG. 2 is an arrangement diagram showing a state in which a plurality of average strain gauges shown in the first and fifth drawings are used and arranged so as to cover the entire measurement target section. 1, 2.13, 17, 3], 32.43...
・Connection part, connection thread part, 3.4, 16...Concrete attachment part, 5.35...Central part, 6
．． 36,51.52...Strain detector (strain gauge), 7,37...Concrete non-adhesive area, 8,38...Output cable, 9.
39...Heat shrink tube, 11.41...
...Knurled surface, 12.42...
...Fixing screw, 21.22 ...Pipe,
5...Screw, U...Welded part, 5.
...Strain gauge adhesive part, 26 ...Rubber filler, 61.88 ...Reinforcement bar, 62
・・・・・・Concrete structure, 63・・・・・・
Gap location, 71.81...Measurement target section,
72, 73, 82.83...Predetermined length (I), 74, 75.84, 85...Average strain meter, 76, 86...Connection fitting,
77, 87... Concrete adhesion piece, Ll
+Lt・・・Strain measurement line. Patent applicant: Pacific Consultants Co., Ltd. Figure 1 s2 (a) (b) Figure 4 jI5 Figure 186 (a) (b) Figure 7 Figure 8 Figure 9 Figure 10 (a) (b) Figure 11 Ll 2 Figure 12

Claims (6)

[Claims] (1) In a method for measuring deformation of reinforced concrete or concrete structures, one or more pairs of strain measurement lines are set within the reinforced concrete or concrete structure at a certain distance apart in the bending direction over the measurement target section, and the measurement is performed. Divide the target section into one or several types of predetermined lengths, calculate the average strain for each of the sections and each of the strain measurement lines, and based on the average strain of the pair corresponding to each of the sections thus calculated. 1. A method for measuring deformation of reinforced concrete or concrete structures, the method comprising measuring the deformation of reinforced concrete or concrete structures. (2) One average strain gauge is provided in each of the sections, and both ends of the average strain gauges are connected to each other to have a length suitable for the measurement target section, and these are connected in one pair or in multiple pairs. Deformation of reinforced concrete or a concrete structure according to claim 1, characterized in that the average strain is determined for each section and for each measurement line by each of the average strain gauges. Measuring method. (3) One average strain gauge is provided in each of the above sections, and one or two pairs are provided on the inner wall surface of each average strain gauge so as to face each other with an angular separation of 180°. Detectors are arranged on one or two pairs of the strain measurement lines in correspondence with each other, and both ends of the average strain gauges are connected to each other to have a length corresponding to the measurement section, and The method for measuring deformation of reinforced concrete or concrete structures according to claim 1, characterized in that the average strain is determined for each section and for each measurement line using a strain detector. (4) An average strain meter used to measure the deformation of reinforced concrete or concrete structures, which has a bar shape with a predetermined length as a whole, and has a concrete attachment part that also serves as a connection part at both ends, An average strain meter characterized in that a non-concrete part is provided which is treated to prevent concrete from adhering to the part other than the concrete adhering part, and a strain detector is provided inside the central part. (5) The whole consists of a cylindrical pipe of a predetermined length, with one pipe facing the inner wall of the central part at an angular interval of 180°.
5. The average strain meter according to claim 4, comprising a pair or two pairs of strain detectors. (6) The average strain gauge according to claim 5, wherein the inner diameter of the inner wall surface on which the strain detector is provided at the center of the cylindrical pipe is larger than the inner diameter of other parts.
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