JP2004271289A - Uniaxial tensile tester for concrete - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a uniaxial tensile tester for directly and simply finding uniaxial tensile strength of concrete. <P>SOLUTION: This uniaxial tensile tester is equipped with upper and lower guide members 12, 14; 12, 16 firmly attached respectively to upper and lower end side faces of a concrete test piece to be tested, a hold portion 18 for holding the upper guide members with space left between a lower face of the test piece and a lower face of the lower guide member, and a loading portion 20 for applying downward force to the lower guide members. The tester is characterized in that tensile force is applied to the test piece by applying downward force to the loading portion. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention generally relates to a uniaxial tensile test apparatus for concrete. More specifically, the present invention relates to a uniaxial tensile test device capable of easily obtaining a uniaxial tensile strength of concrete.
[0002]
[Prior art]
As a test method for obtaining the tensile strength of concrete, various methods have been proposed in addition to a tensile test (JIS A 1113) specified in Japanese Industrial Standards.
[0003]
[Problems to be solved by the invention]
However, the tensile test stipulated in Japanese Industrial Standards is not a method of directly measuring the tensile strength, but a method of indirectly measuring the tensile strength, so the obtained tensile strength accurately represents the tensile strength of the concrete. It is hard to say that it is. In addition, concrete shows brittle fracture properties under the action of tensile force, and some of the currently proposed methods can easily obtain satisfactory test results due to the bias in the location where cracks occur. At present, there is nothing that can be done.
[0004]
Therefore, an object of the present invention is to provide a uniaxial tensile test apparatus that can directly and easily determine the uniaxial tensile strength of concrete.
[0005]
[Means for Solving the Problems]
The uniaxial tensile test apparatus for concrete according to claim 1 of the present application comprises upper and lower guide members firmly attached to upper and lower side surfaces of a concrete specimen to be tested, and a lower surface and a lower surface of the concrete specimen, respectively. A holding portion for holding the upper guide member at a distance from the lower surface of the lower guide member, and a loading portion for applying a downward force to the lower guide member; The method is characterized in that a tensile force is applied to the concrete specimen by applying a downward force to the portion.
[0006]
The uniaxial tensile test device for concrete according to claim 2 of the present application is the device according to claim 1, wherein the lower guide member is provided with three or four through holes extending in the axial direction at an equal angle from each other. Provided, wherein the holding portion has a bottom plate, and the bottom plate passes through each of the through holes with a gap, and has three or four struts whose upper end is fixed to the upper guide member, It is characterized by being fixed so as to be orthogonal to the bottom plate.
[0007]
The uniaxial tensile test apparatus for concrete according to claim 3 of the present application is the apparatus according to claim 2, wherein the upper guide member is provided with three or four through holes extending in the axial direction at an equal angle from each other. Wherein the load portion has a bottom plate, and the bottom plate passes through each of the through holes of the upper guide member with a gap, and a lower end of the bottom plate contacts the lower guide member. The loading column is fixed so as to be orthogonal to the bottom plate of the loading portion, and a downward force applied to the bottom plate of the loading portion is transmitted to the lower guide member via the loading column. It is characterized by being constituted so that it may be performed.
[0008]
The uniaxial tensile test device for concrete according to claim 3 of the present application is the device according to any one of claims 1 to 3, wherein each of the guide members is attached to a side surface at both ends of the concrete specimen. A taper ring having at least a portion of an outer surface formed in a tapered shape, and a guide ring having an inner surface formed in a tapered shape so as to complement the outer surface of the tapered ring, respectively. is there.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, a concrete uniaxial tensile test apparatus according to a preferred embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is an exploded perspective view of a uniaxial tensile test device for concrete according to a preferred embodiment of the present invention. A uniaxial tensile tester for concrete according to a preferred embodiment of the present invention, which is generally indicated by reference numeral 10 in FIG. 1, includes a pair of tapered rings 12 attached to both side surfaces of a cylindrical concrete specimen to be tested. It has.
[0010]
At least a part of the outer surface of the tapered ring 12 (in the illustrated example, the upper tapered ring 12 is the lower half of the outer surface, and the lower tapered ring 12 is the upper half of the outer surface) is formed in a tapered shape. It is a metal ring-shaped member provided with irregularities 12a on the inner surface. The inner diameter of the tapered ring 12 is formed to be slightly larger than the diameter of the concrete specimen. The taper ring 12 is attached with an adhesive to an end of a concrete specimen to which a reinforcing sheet such as a two-way aramid fiber sheet is adhered.
The unevenness 12a on the inner surface of the tapered ring 12 strengthens the adhesion between the tapered ring 12 and the concrete specimen and helps to smoothly transmit the force from the tapered ring 12 to the concrete specimen. Note that the height of the tapered ring 12 is typically 50 mm.
[0011]
The uniaxial tensile tester 10 for concrete also includes a first guide ring 14 disposed outside the upper taper ring 12. The first guide ring 14 is a metal ring-shaped member having substantially the same height as the tapered ring 12 and having an inner surface formed in a tapered shape so as to complement the outer surface of the tapered ring 12. The first guide ring 14 is provided with three through holes 14a extending in the axial direction at an angle of 120 ° from each other. On the lower surface of the first guide ring 14, concave portions 14b are provided between adjacent through holes 14a at an angle of 120 ° from each other.
[0012]
The uniaxial tensile tester 10 for concrete also includes a second guide ring 16 disposed outside the lower taper ring 12. The second guide ring 16 is a metal ring-shaped member having substantially the same height as the tapered ring 12 and having an inner surface formed in a tapered shape so as to complement the outer surface of the tapered ring 12. The second guide ring 16 is provided with three through holes 16a extending in the axial direction at an angle of 120 ° from each other. On the upper surface of the second guide ring 16, concave portions 16b are provided between adjacent through holes 16a at an angle of 120 ° from each other.
[0013]
The tapered ring 12 and the guide ring 14 and the tapered ring 12 and the guide ring 16 each constitute a guide member.
[0014]
The uniaxial tensile tester 10 for concrete also includes a retaining portion 18. The holding part 18 has a circular bottom plate 18a having a diameter substantially the same as the outer diameter of the guide rings 14, 16. Three columnar columns 18b are attached to the bottom plate 18a at an angle of 120 ° so as to be orthogonal to the bottom plate 18a. The column 18b is firmly fixed to the bottom plate 18a with screws 22 or the like. The length of each support 18b is longer than the height H of the concrete specimen, and the diameter of each support 18b is smaller than the diameter of the through hole 16a of the guide ring 16. In addition, the bottom plate 18a and the support 18b are formed of metal.
[0015]
The uniaxial tensile test apparatus 10 for concrete further includes a loading portion 20. The loading portion 20 has a circular loading plate 20a having substantially the same diameter as the outer diameter of the guide rings 14, 16. Three cylindrical loading columns 20b are attached to the loading plate 20a at an angle of 120 ° so as to be orthogonal to the loading plate 20a. The fixing of the loading column 20b to the loading plate 20a is performed firmly with screws 22 or the like. The length of each loading column 20b is longer than the height H of the concrete specimen, and the diameter of each loading column 20b is smaller than the diameter of the through hole 14a of the guide ring 14. In addition, the loading plate 20a and the loading column 20b are formed of metal.
[0016]
Next, how to use the uniaxial tensile test apparatus 10 configured as described above will be described mainly with reference to FIG. First, reinforcing sheets are bonded to both ends of a concrete specimen to be tested (see FIG. 5A). Next, an upper taper ring 12 is attached to the upper end of the concrete specimen to which the reinforcing sheet is adhered so that the taper of the outer surface converges downward with an adhesive. The guide rings 14 and 16 are passed through the concrete specimen, and the lower taper ring 12 is attached to the lower end of the concrete specimen with an adhesive so that the taper of the outer surface converges upward (see FIG. 5B). The guide ring 14 is fitted into the tapered ring 12 of the above, and the guide ring 16 is fitted into the lower tapered ring 12. Next, the respective pillars 18b of the holding part 18 are passed through the respective through holes 16a of the guide ring 16 from below, and the ends thereof are housed in the recesses 14b of the guide ring 14, and the tips of the respective pillars 18b and the guide ring 14 are screwed together. Fix (see FIG. 5 (c)). Next, the loading struts 20b of the loading portion 20 pass through the through holes 14a of the guide ring 14 from above (see FIG. 5D), and the tips of the loading struts 20b are accommodated in the recesses 16b of the guide ring 16. In such a state, when a downward force (see arrows in FIGS. 2 and 4) is applied to the loading plate 20a, the lower guide ring 14 is supported even though the upper guide ring 14 is supported by the column 18b. Because a downward force is applied to 16, an axial tensile force is applied to the tapering 12 (and thus the concrete specimen).
[0017]
In the tensile test by the uniaxial tensile tester 10 performed by the present inventors, the fracture surface of the concrete test piece was substantially perpendicular to the direction in which the load was applied. This shows that the use of the uniaxial tensile test apparatus 10 of the present invention makes it possible to apply a tensile force almost uniformly in the axial direction of the concrete specimen.
[0018]
The present invention is not limited to the above embodiments of the invention, and various modifications can be made within the scope of the invention described in the claims, which are also included in the scope of the invention. Needless to say, it is.
[0019]
For example, in the above embodiment, only the half of the outer surface of the tapered ring 12 is formed in a tapered shape, but the entire outer surface of the tapered ring may be formed in a tapered shape. In the above embodiment, the number of the through holes 14a and 16a of the guide rings 14 and 16 is three, but four through holes may be provided. In the above-described embodiment, the guide rings 14 and 16 are ring-shaped members. However, the guide rings 14 and 16 may have a rectangular outer shape as long as an opening that fits the tapered ring 12 is provided. Further, the bottom plate 18a of the holding portion 18 and the loading plate 20a of the loading portion 20 need not be circular.
[0020]
【The invention's effect】
According to the present invention, it is possible to easily obtain the uniaxial tensile strength of concrete with a device having a relatively simple structure. In the present invention, it is possible to apply a load using a general-purpose Amsler, so that the cost of the apparatus can be reduced. In addition, the specimen of the present invention can apply a stable tensile force to the specimen without eccentricity and inclination.
[Brief description of the drawings]
FIG. 1 is an exploded perspective view of a uniaxial tensile test device according to a preferred embodiment of the present invention.
FIG. 2 is a front view of the uniaxial tensile test apparatus of FIG.
FIG. 3 is a plan view of the uniaxial tensile test apparatus of FIG. 1;
FIG. 4 is a sectional view taken along lines 4-4 of FIG. 3;
FIG. 5 is a series of diagrams showing a procedure of a tensile test by a uniaxial tensile test device of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Uniaxial tensile test apparatus 12 Taper ring 14, 16 Guide ring 18 Holding part 20 Loading part

Claims (4)

A uniaxial tensile tester for concrete,
Upper and lower guide members rigidly attached to the upper and lower sides of the concrete specimen to be tested, respectively;
A holding portion that holds the upper guide member in a state where a space is provided between the lower surface of the concrete specimen and the lower surface of the lower guide member,
A loading portion for applying a downward force to the lower guide member,
The apparatus of any preceding claim, wherein the apparatus is configured to apply a downward force to the load portion to apply a tensile force to the concrete specimen. The lower guide member is provided with three or four through holes extending in the axial direction at an equal angle to each other,
The holding portion has a bottom plate, and the bottom plate passes through each of the through holes with a gap, and three or four struts whose upper end is fixed to the upper guide member are orthogonal to the bottom plate. 2. The device according to claim 1, wherein the device is fixed to the device. The upper guide member is provided with three or four through holes extending in the axial direction at an equal angle to each other,
The load portion has a bottom plate, and the bottom plate has three or four loading columns that pass through each of the through holes of the upper guide member with a gap and a lower end contacts the lower guide member, It is fixed so as to be orthogonal to the bottom plate of the load part,
The apparatus according to claim 2, wherein a downward force applied to the bottom plate of the load portion is configured to be transmitted to the lower guide member via the load support column. . Each of the guide members is attached to a side surface of both ends of the concrete specimen, and at least a part of the outer surface is formed in a tapered shape having a tapered shape. 4. A device according to claim 1, further comprising a guide ring having a curved inner surface.

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