JP7847776B2 - Force testing device - Google Patents

Description

Article 30, Paragraph 2 of the Patent Law applies. Meeting name: Briefing session "Briefing session on full-scale seismic isolation testing facilities", Organizer: Japan Seismic Isolation Research Promotion Foundation, Date: April 11, 2022. Publisher: Japan Seismic Isolation Research Promotion Foundation, Publication name: Pamphlet "Regarding the establishment of full-scale seismic isolation testing facilities for the further development of seismic isolation and vibration control technologies", Publication date: April 11, 2022. Website access location: Japan Seismic Isolation Research Promotion Foundation, Address: http://jsil.or.jp/, http://jsil.or.jp/facility.html, Website posting date: July 12, 2022. Meeting name: Seminar "Challenges inherent in existing full-scale testing machines and their solutions", Organizer: Japan Seismic Isolation Research Promotion Foundation, Date: August 20, 2022.

This invention relates to a load testing device that simultaneously applies vertical and horizontal forces to a test specimen simulating a structure or its constituent members, and measures the response of the test specimen. It also represents a technology that prevents frictional and inertial forces from being mixed into the horizontal force measurements of a three-way or two-way dynamic load testing machine for seismic isolation devices.

When constructing a building, full-scale experiments are conducted to demonstrate the reliability of structural components by applying forces to test specimens related to those components and measuring their response.

For example, Patent Document 1 discloses a test apparatus comprising a vertical swivel joint additional vibrator, a horizontal swivel joint additional vibrator, a slide bearing that transmits the excitation force and guides the table vertically with minute friction to restrain rotational motion, and a slide bearing shaft support device, which applies vertical motion alone, horizontal motion alone, or simultaneous vertical and horizontal coupled excitation force to the object under test.
Furthermore, Patent Document 2 discloses a test apparatus comprising: a first force-applying part that can reciprocate vertically with respect to a first holding part that holds one end of a flexible member; a second force-applying part that reciprocates in a first horizontal direction with respect to a second holding part that holds the other end of the flexible member; and a third force-applying part that reciprocates in a second horizontal direction different from the first horizontal direction with respect to the second holding part.
In the configurations described in Patent Documents 1 and 2, there is a possibility that the response of the test specimen cannot be accurately measured. For example, in the configuration of Patent Document 2, a load cell is provided on a joint that is rotatably mounted horizontally to hold the other end of the flexible member, and the horizontal force acting on the flexible member is measured using this load cell. In this case, the horizontal force measured by the load cell includes the inertial force acting on the second holding part when it is moved from a stationary position or when the direction of movement of the second holding part is changed. In addition, the frictional force generated between the second support part and the support base that rotatably supports the second support part is also included in the horizontal force measured by the load cell.
Thus, in the configurations of Patent Documents 1 and 2, even when attempting to measure the horizontal force acting on the test specimen, the measured horizontal force includes inertial force and frictional force.

In contrast, Patent Document 3 discloses a testing apparatus comprising: a lower reaction beam fixed to a reaction floor; a movable table positioned horizontally on the lower reaction beam to fix a test specimen; a retaining grid that presses down on the movable table from above; a retaining grid link fixed at one end to a reaction wall or reaction floor and the other end to the retaining grid; an upper reaction beam that fixes the upper end of the test specimen; and an upper reaction beam link fixed at one end to a reaction wall and the other end to the upper reaction beam.
The upper reaction beam is constrained from horizontal movement by upper reaction beam links. Load cells are attached to the upper reaction beam links.
A through-rod is provided so as to penetrate the lower reaction beam and the retaining grid. The through-rod is fixed to the upper reaction beam and supports the upper reaction beam. The through-rod includes an upper ram cylinder fixed between the retaining grid and an upper block located above the retaining grid, and a lower ram cylinder fixed between the lower reaction beam and a lower block located below the lower reaction beam. A horizontal actuator is attached to the movable table, with one end attached to the reaction wall.
The through-rod is fixed to the reaction beam via a spherical washer. This spherical washer suppresses the generation of horizontal forces due to bending and shearing of the through-rod, making the horizontal force transmitted from the through-rod to the reaction beam negligible.

In the test apparatus described above, for example, when performing a shear test, a horizontal actuator is activated to move the movable table horizontally, thereby applying a horizontal force to the test specimen. The load cell of the upper reaction beam link measures the horizontal force acting on the test specimen.
In this way, the horizontal force measured is not the horizontal force acting on the movable table which is moved horizontally by the horizontal actuator, but rather the horizontal force acting from the movable table through the test specimen to the upper reaction beam that fixes the upper end of the test specimen on either side of the movable table. Since the horizontal force measured in this way does not include the inertial force when moving the movable table or the frictional force acting between the movable table and other members that support it, the force acting on the test specimen can be clearly determined.

However, in the configuration of Patent Document 3, a through rod is provided to support the upper reaction beam, extending from the lower reaction beam to the upper reaction beam. In such a configuration, the structure is complex, requiring the provision of spherical washers at the joint between the through rod and the upper reaction beam to prevent the generation of horizontal forces due to bending and shearing of the through rod. Therefore, implementing the configuration of Patent Document 3 would be costly.
Furthermore, although a large vertical load acts on the test specimen placed on the movable table described in Patent Document 3, the movable table is sandwiched between ram jacks and a retaining grid, and a large frictional force acts on the upper and lower surfaces of the movable table. For this reason, it was necessary to increase the capacity of the horizontal jacks.
Furthermore, friction does occur even in the spherical washer portion, and this frictional force can affect the measured horizontal force, sometimes making it impossible to accurately detect the horizontal force.
There is a need for a load testing device that can accurately and in real time detect the horizontal force acting on a test specimen, with a simple configuration.

Japanese Unexamined Patent Publication No. 1-178844 Japanese Patent Publication No. 2002-333392 Patent No. 6842721

The problem that this invention aims to solve is to provide a load testing device that can accurately and in real time detect the horizontal force acting on a test specimen and can be implemented with a simple structure.

The inventors have invented a technique for a dynamic load testing device for seismic isolation devices (for example, a three-way or two-way dynamic load testing device) that prevents frictional and inertial forces from being mixed into the horizontal force measurement of a test specimen placed on a vibration table. This technique involves measuring the horizontal force on the specimen placed on the vibration table on the side of the reaction beam, where the inertial force when moving the vibration table and the frictional force acting between the vibration table and the supporting members are not mixed in. The measurement is taken directly as the sum of a first horizontal force measured by a reaction force detector installed between the reaction wall and the reaction beam via the reaction beam that fixes the specimen, and a second horizontal force transmitted by the deformation of a rubber support material joined to the reaction beam.
To solve the above problems, the present invention employs the following means.
In other words, the present invention relates to a load-bearing test apparatus (for example, a three-axis load-bearing test apparatus or a two-axis load-bearing test apparatus) that applies forces simultaneously from the vertical and horizontal directions to a test specimen relating to a structure or a component of said structure and measures the response of said test specimen, and is an invention of a technique for preventing frictional force and inertial force from being mixed into the horizontal force measurement value, comprising: a plurality of vertical dynamic jacks provided above a reaction floor; an excitation table installed above the vertical dynamic jacks and on which the test specimen is fixed to the upper surface; a reaction beam that fixes the upper end of the test specimen; and a plurality of horizontal dynamic jacks, one end of which is fixed to the reaction wall and the other end of which is fixed to the excitation table. This invention provides a technology to prevent frictional and inertial forces from being mixed into the horizontal force measurement values of a three-way or two-way dynamic loading test machine for seismic isolation devices, characterized in that the horizontal force acting on the test specimen is the sum of a first horizontal force measured by the reaction force detector and a second horizontal force transmitted by the deformation of the rubber support material, comprising a jack, a reaction force detector with one end fixed to the reaction beam and the other end fixed to the reaction wall, a rubber support material with its lower end provided so as to be immovable relative to the reaction floor and its upper end joined to the reaction beam to support the reaction beam, and a tensioning member with one end fixed to the reaction beam and the other end fixed to the reaction floor, wherein the horizontal force acting on the test specimen is the sum of a first horizontal force measured by the reaction force detector and a second horizontal force transmitted by the deformation of the rubber support material.
In this configuration, the test specimen is placed on an excitation table. The upper end of the test specimen is fixed by a reaction beam. When the excitation table is moved by vertical and horizontal dynamic jacks, the test specimen is subjected to a horizontal force in addition to a vertical force. The horizontal force acting on the test specimen is transmitted as a compressive or tensile force to a reaction force detector installed between the reaction wall and the reaction beam via the reaction beam. Here, the reaction beam is supported from below by a rubber support whose lower end is fixed relative to the reaction floor, and the reaction beam is movable relative to the reaction floor, so the transmission of this horizontal force is not hindered by the rubber support. The horizontal force transmitted to the reaction force detector in this manner is measured as the first horizontal force.
When the reaction force detector detects the first horizontal force in the manner described above, the reaction force detector undergoes a slight compressive or elongative deformation due to the influence of the horizontal force transmitted to it, and the reaction beam moves horizontally by the amount of this compression or elongation. Of the horizontal force transmitted to the test specimen, the horizontal force consumed for the deformation of the reaction force detector and the movement of the reaction beam cannot be measured as the first horizontal force by the reaction force detector. Here, the amount of compression and elongation of the reaction force detector is minute, and the amount of movement of the reaction beam and the deformation of the rubber support material that accompany it are also minute. The relationship between the deformation of the rubber support material and the horizontal force acting on the rubber support material is basically proportional in the initial deformation stage when the deformation is minute. Therefore, if this relationship is understood in advance, the portion of the horizontal force transmitted to the reaction beam that is not measured as the first horizontal force by the reaction force detector can be identified as the second horizontal force, i.e., the component transmitted by the deformation of the rubber support material, based on the deformation of the rubber support material.
By adding together the first horizontal force detected by the reaction force detector and the second horizontal force transmitted by the deformation of the rubber support material, the horizontal force acting on the test specimen can be accurately detected.
Here, the first and second horizontal forces are not measured with respect to the excitation table that is directly moved by the horizontal dynamic jack. Therefore, the first and second horizontal forces do not include the inertial force when moving the excitation table or the frictional force acting between the excitation table and the member supporting it.
Furthermore, because the reaction beam is connected to the reaction floor by tensioning members, the vertical displacement of the reaction beam is suppressed, while it is not rigidly constrained in the horizontal direction. Therefore, the horizontal force acting on the rubber support is less likely to be transmitted vertically through the tensioning members. This improves the accuracy of horizontal force measurement.
The combined effect of these factors allows for the accurate detection of horizontal forces acting on the test specimen.
Furthermore, in the above configuration, since the reaction beam only requires rubber support members and tensioning members, the structure becomes simple.
Furthermore, in the configuration described above, since it is not affected by frictional and inertial forces, it is possible to detect horizontal forces in real time.
As a result, it becomes possible to provide a load testing device that can accurately and in real time detect the horizontal force acting on the test specimen and can be realized with a simple structure.

In one embodiment of the present invention, the rubber support material is a single-layer rubber bearing or a laminated rubber bearing consisting of multiple layers.
With this configuration, the rubber support material, whether a single-layer or laminated rubber bearing, has high vertical rigidity, and vertical deformation is suppressed. Therefore, when a horizontal force acts on the rubber support material, vertical deformation of the rubber support material is suppressed, and the rubber support material can deform smoothly in the horizontal direction by the amount of the applied horizontal force. Thus, the second horizontal force can be accurately detected.

In one embodiment of the present invention, a plurality of rubber support members are installed, and each of the rubber support members is constrained under a predetermined compressive stress by a prestressing force from a tensioning member provided at an adjacent position.
With this configuration, the prestressing force of the tensioning member restrains the rubber support material, which has high vertical rigidity, under compressive stress. This suppresses the vertical displacement of the rubber support material while minimizing its dependence on surface pressure. As a result, the second horizontal force caused by the horizontal deformation of the rubber support material can be measured stably.

In one embodiment of the present invention, a plurality of reaction force detectors are arranged between the reaction beam and the reaction wall, each reaction force detector has a built-in load cell, and joints for reducing bending moment are provided at both ends.
With this configuration, a load cell capable of accurately measuring axial force is built into the reaction force detector, and joints that reduce bending moment are provided at both ends of the reaction force detector, thereby suppressing the generation of bending moment on the load cell due to the displacement of the reaction beam.

According to the present invention, it is possible to provide a load testing device that can accurately and in real time detect the horizontal force acting on a test specimen and can be realized with a simple structure.

This is a perspective view showing the configuration of a force testing apparatus according to an embodiment of the present invention. Figure 1 is a schematic plan view showing the configuration of the load testing apparatus. Figure 2 shows the configuration of the load testing apparatus as viewed from a second direction. Figure 2 shows the configuration of the load testing apparatus as viewed from the first direction. This is a cross-sectional view taken along the line I-I in Figure 2. This is a cross-sectional view of the area indicated by arrow A in Figure 3, showing the anchoring structure at the top of the tensioning member of the load testing device. This is a cross-sectional view of the area indicated by arrow B in Figure 3, showing the anchoring structure at the lower part of the tensioning material. This figure shows the state when a horizontal force is applied to the test specimen in the above-mentioned load-bearing test apparatus. This figure shows an example of the relationship between the amount of deformation of the rubber support material and the second horizontal force generated by the deformation of the rubber support material.

The present invention relates to a load testing device (for example, a three-axis load testing device or a two-axis load testing device) that simultaneously applies vertical and horizontal forces to a test specimen simulating a structure and measures the response of the test specimen. The present invention embodies a technology that prevents frictional and inertial forces from being mixed into the horizontal force measurement values of a three-way or two-way dynamic load testing machine for seismic isolation devices, as a load testing device. Specifically, the load testing apparatus of the present invention comprises an excitation table installed on top of a vertical dynamic jack provided above a reaction floor, a reaction beam that fixes the upper end of the test specimen, a horizontal dynamic jack with one end fixed to a reaction wall and the other end fixed to the excitation table, a reaction force detector with one end fixed to the reaction beam and the other end fixed to the reaction wall, and a rubber support material whose lower end is provided so as not to move relative to it and whose upper end is joined to the reaction beam to support the reaction beam, characterized in that the horizontal force acting on the test specimen is the sum of a first horizontal force measured by the reaction force detector and a second horizontal force transmitted by the deformation of the rubber support material.
Hereinafter, with reference to the attached drawings, an embodiment for implementing the load testing apparatus according to the present invention will be described based on the drawings.
Figure 1 is a perspective view showing the configuration of a load testing apparatus according to an embodiment of the present invention. Figure 2 is a schematic plan view showing the configuration of the load testing apparatus of Figure 1. Figure 3 is a view of the load testing apparatus of Figure 2 from a second direction. Figure 4 is a view of the load testing apparatus of Figure 2 from a first direction. Figure 5 is a cross-sectional view taken along the line I-I in Figure 2.
The loading test apparatus 10 shown in Figures 1 to 5 applies forces to the test specimen T simultaneously from the vertical and horizontal directions and measures the response of the test specimen T. Here, the test specimen T in the loading test apparatus 10 refers to a structure or a component of a structure. In this embodiment, the test specimen T is exemplified as a seismic isolation device incorporated into a structure, more specifically, a laminated rubber bearing. Other types of seismic isolation and vibration control devices other than laminated rubber bearings, such as sliding bearings, can be applied as the test specimen T. In addition to seismic isolation devices, other examples of test specimens T include column test specimens, wall test specimens, and scaled-down structural frame test specimens that simulate a structure or a part thereof.
The load testing apparatus 10 is installed in the test pit 1. The test pit 1 has a reaction floor 2 and a pair of reaction walls 3. The reaction floor 2 is formed on the ground with a predetermined thickness in the vertical direction, for example, on the foundation of a building. The reaction floor 2 is formed in a rectangular shape in plan view. The pair of reaction walls 3 are spaced apart in a first direction D1 along the floor surface of the reaction floor 2. The pair of reaction walls 3 are formed rising vertically upward from both ends of the reaction floor 2 in the first direction D1. The pair of reaction walls 3 are provided to extend in a vertical plane that includes a second direction D2 perpendicular to the first direction D1 in the horizontal plane. The pair of reaction walls 3 are provided so as to be immovable relative to the reaction floor 2. The reaction floor 2 and the reaction walls 3 are formed to be sufficiently strong so as to be able to receive the reaction forces input from the vertical dynamic jacks 21, horizontal dynamic jacks 22, reaction force detectors 30, etc., which will be described later, during the test.

The load-bearing test device 10 (three-axis load-bearing test device) comprises an excitation table 11, a reaction beam 13, a rubber support member 15, a tension member 17, a plurality of vertical dynamic jacks 21, a plurality of horizontal dynamic jacks 22, and a reaction force detector 30.
As shown in Figures 3 to 5, the excitation table 11 is positioned above the reaction floor 2 at intervals. The excitation table 11 is installed above a plurality of vertical dynamic jacks 21. The excitation table 11 is supported from below by the plurality of vertical dynamic jacks 21. The excitation table 11 comprises a base 11a, an excitation table body 11b, and a bearing 11c. The base 11a is, for example, rectangular in plan view and has a table shape formed along the horizontal plane. The base 11a is supported on a plurality of vertical dynamic jacks 21. The excitation table body 11b is positioned above the base 11a at intervals. The excitation table body 11b is, like the base 11a, for example, rectangular in plan view and has a table shape formed along the horizontal plane. The bearing 11c is positioned between the upper surface of the base 11a and the lower surface of the excitation table body 11b. The bearing 11c is, for example, a plurality of ball bearings, and supports the vibration table body 11b on the base 11a so that it can move freely in the horizontal plane. The lower end of the test specimen T is fixed to the upper surface of the vibration table body 11b.

The reaction beam 13 is installed above the excitation table 11 at intervals. As shown in Figures 2 to 5, the reaction beam 13 integrally comprises a reaction beam body 13a, a first beam member 13b, and a second beam member 13c. The reaction beam body 13a is formed to cover the excitation table 11 from above. The upper end of the test specimen T is fixed to the lower surface of the reaction beam body 13a.
The first beam member 13b and the second beam member 13c are spaced apart in the second direction D2. The first beam member 13b and the second beam member 13c are joined to both ends of the reaction beam body 13a in the second direction D2. In a plan view, the first beam member 13b and the second beam member 13c each extend outwards from the reaction beam body 13a in the first direction D1. The first beam member 13b and the second beam member 13c are arranged parallel to each other.
The reaction beam 13 is spaced apart from the reaction floor 2, the reaction wall 3, and the support wall 14, which will be described next, and is movable relative to them in the horizontal direction.

Support walls 14 are provided below the first beam member 13b and the second beam member 13c, respectively. The support walls 14 are formed so as to overlap the first beam member 13b and the second beam member 13c in a plan view. The lower end of the support wall 14 is fixed to the reaction floor 2. The support wall 14 extends vertically upward from the reaction floor 2. The upper end of the support wall 14 is formed with a vertical gap between it and the lower surfaces of the first beam member 13b and the second beam member 13c.
The support wall 14, like the pair of reaction walls 3, is fixed to the reaction floor 2 in an immovable manner.
In this embodiment, the support wall 14 is shown to be provided independently of the reaction wall 3, but it is not limited to this. For example, in Figure 2, another reaction wall 3 may be provided so as to be perpendicular to the reaction wall 3 provided so as to be provided so as to be provided so as to be provided in a vertical plane including the first direction D1, and so as to be perpendicular to the reaction wall 3 provided so as to be provided so as to be provided so as to be provided so as to be positioned with a vertical gap between its upper end and the lower surfaces of the first beam member 13b and the second beam member 13c.

The rubber support members 15 are provided between the upper end of the support wall 14 and the lower surfaces of the first beam member 13b and the second beam member 13c. Multiple rubber support members 15 are provided at intervals in the horizontal plane. In this embodiment, the rubber support members 15 are provided at three locations below each of the first beam member 13b and the second beam member 13c, at intervals in the first direction D1.
The rubber support material 15 is either a single-layer rubber bearing or a laminated rubber bearing consisting of multiple layers. In this embodiment, the rubber support material 15 is a laminated rubber bearing comprising multiple laminated rubber layers 15c between an upper flange 15a and a lower flange 15b. A rubber support material 15 consisting of such a laminated rubber bearing has high vertical rigidity.
The lower end 15e of each rubber support member 15, i.e., the lower surface of the lower flange 15b, is fixed to the upper end of the support wall 14. This ensures that the lower end of each rubber support member 15 is immovable relative to the reaction floor 2. The upper end 15d of each rubber support member 15, i.e., the upper surface of the upper flange 15a, is joined to the lower surfaces of the first beam member 13b and the second beam member 13c of the reaction beam 13. In this way, the multiple rubber support members 15 support the reaction beam 13 from below.

As shown in Figures 3 and 4, the tensioning member 17 is fixed at one end to the reaction beam 13, is installed so as to penetrate the support wall 14 vertically, and the other end is fixed to the reaction floor 2. As shown in Figure 2, in a plan view, multiple tensioning members 17 are provided adjacent to each rubber support member 15.
Figure 6 is a cross-sectional view taken along the line A in Figure 3, showing the anchoring structure of the upper part of the tensioning member of the load-bearing test apparatus. Figure 7 is a cross-sectional view taken along the line B in Figure 3, showing the anchoring structure of the lower part of the tensioning member.
As shown in Figures 3, 4, 6, and 7, the tensioning member 17 is made of PC steel strands (or PC steel bars) and is provided penetrating the first beam member 13b, the second beam member 13c, and the support wall 14.

As shown in Figure 6, one end 17a of the tensioning member 17 is fixed to the upper surfaces of the first beam member 13b and the second beam member 13c using an upper fixing part 19. The upper fixing part 19 has a base plate 19a, a chair tube 19b, an anchor plate 19c, a ring nut 19d, and an anchor head 19e. The base plate 19a is provided along the upper surfaces of the first beam member 13b and the second beam member 13c. The chair tube 19b is cylindrical and is provided above the base plate 19a. In this embodiment, a PC steel strand, formed by twisting together multiple steel wires, is used as the tensioning member 17. At one end 17a, this PC steel strand is separated into multiple PC steel strands, and each of these PC steel strands is fixed individually. More specifically, each PC steel strand constituting the tensioning member 17 is inserted inside the chair tube 19b. The anchor plate 19c is provided to cover the upper end of the chair tube 19b. The ring nut 19d is seated on the upper surface of the anchor plate 19c. The anchor head 19e is provided inside the ring nut 19d and is designed to displace vertically as the ring nut 19d rotates. One end 17a of the tensioning member 17 is restrained from downward movement by a tapered fastener 17d attached to the anchor head 19e. The end 17a of the tensioning member 17, the ring nut 19d, and the anchor head 19e are covered by a cap 19f. Specifically, the PC steel strands appear to be a single steel wire, but are actually made by twisting together thinner steel wires. These strands are bundled and transported from the factory, and they are installed in a straight line without being twisted.

As shown in Figure 7, the other end 17b of the tensioning member 17 is fixed at a lower position, at a predetermined distance or more from the reaction beam 13. The other end 17b of the tensioning member 17 is anchored to the reaction floor 2 using a lower anchoring part 18. The lower anchoring part 18 has a base plate 18a, a chair tube 18b, an anchor plate 18c, a ring nut 18d, and an anchor head 18e. The base plate 18a is provided so as to be embedded in the lower surface of the reaction floor 2. The chair tube 18b is cylindrical and is provided below the base plate 18a. The PC steel strands are separated into multiple PC steel strands at the other end 17b, just as at the one end 17a, and each of these PC steel strands is anchored individually. More specifically, each PC steel strand constituting the tensioning member 17 is inserted inside the chair tube 18b. The anchor plate 18c is provided to cover the lower end of the chair tube 18b. The ring nut 18d is seated on the lower surface of the anchor plate 18c. The anchor head 18e is provided inside the ring nut 18d and is designed to displace vertically as the ring nut 18d rotates. The other end 17b of the tensioning member 17 is restrained from upward movement by a tapered fastener 17c attached to the anchor head 18e. The other end 17b of the tensioning member 17, the ring nut 18d, and the anchor head 18e are covered by a cap 18f.

A pipe 17p made of a sheath pipe is embedded in the portion of the support wall 14 through which the tension member 17 is installed. The space between one end 17a and the other end 17b of the tension member 17 is inserted through this pipe 17p. A sheath pipe 17q, which has a smaller diameter than pipe 17p, is inserted into the lower end of pipe 17p. A spiral reinforcement 16 is embedded in the support wall 14 on the outside of the sheath pipe 17q.
A pre-set prestressing force (tensile force) is introduced into the tensioning member 17 by tightening the ring nuts 18d and 19d. Each of the rubber support members 15 is restrained under a predetermined compressive stress due to the prestressing force from the tensioning members 17 installed at adjacent positions.

In this manner, the reaction beam 13 is pressed against the support wall 14 via the rubber support member 15 by the tensioning member 17 into which a prestressing force is introduced, thereby being positioned so as to be unable to be displaced vertically relative to the support wall 14 and the reaction floor 2.
Here, the tension member 17, to which the prestress force has been introduced, is subjected to a geometric horizontal stiffness obtained by dividing the introduced prestress force by the length of the member. That is, when tension is applied to the tension member 17, the stiffness in the horizontal direction perpendicular to the tension member 17 should, in principle, increase. However, in this embodiment, as will be explained later, the reaction beam 13 is provided to be displaceable in the horizontal direction, and the excitation table 11 is excited. The horizontal force acting on the reaction beam 13 from the excitation table 11 via the test specimen T is then measured by the load cell 35 of the reaction force detector 30, which is installed horizontally between the reaction wall 3 and the reaction beam 13. For this reason, if the horizontal constraint on the reaction beam 13 by the tension member 17 is made too strong, it may become impossible to accurately measure the horizontal force acting on the reaction beam 13.
Therefore, in order to prevent the horizontal restraint of the reaction beam 13 from becoming too strong, it is desirable to make the tensioning member 17 as long as possible to lower the geometric horizontal stiffness.
Furthermore, it is desirable that the diameter D of the pipe 17p through which the tensioning member 17 is inserted be set to be sufficiently large throughout the entire height of the support wall 14 that supports the rubber support member 15, so that when the tensioning member 17 deforms by tilting due to the horizontal displacement of the reaction beam 13, it does not come into contact with the inner wall of the pipe 17p and suppress this deformation.

As shown in Figures 3 to 5, multiple vertical dynamic jacks 21 are provided above the reaction floor 2 and each extends vertically. The multiple vertical dynamic jacks 21 are provided, for example, below the four corners of the excitation table 11. The lower end of each vertical dynamic jack 21 is fixed to the reaction floor 2. The upper end of each vertical dynamic jack 21 is fixed to the lower surface of the excitation table 11. Each vertical dynamic jack 21 is driven to extend and retract vertically by hydraulic pressure supplied from an external source.
As shown in Figures 2 to 5, multiple horizontal dynamic jacks 22 are arranged on both sides of the excitation table 11 in the first direction D1. In this embodiment, two horizontal dynamic jacks 22 are provided on each side of the excitation table 11 in the first direction D1, with a gap in the second direction D2. Each horizontal dynamic jack 22 has one end 22a fixed to the reaction wall 3 and the other end 22b fixed to the table body 11b of the excitation table 11. In particular, as shown in Figure 5, both ends 22a and 22b of each horizontal dynamic jack 22 are connected to the reaction wall 3 and the excitation table 11, respectively, via joint members 22j, so that the horizontal dynamic jack 22 can rotate around the joint member 22j.
Two horizontal dynamic jacks 22 located on one side of the excitation table 11 in the first direction D1 are positioned at an angle of approximately 10° with respect to the first direction D1, such that the distance between them gradually increases as they move away from the excitation table 11 when viewed from above, as shown in Figure 2. The same applies to the two horizontal dynamic jacks 22 located on the other side of the excitation table 11 in the first direction D1.
As these multiple vertical dynamic jacks 21 and multiple horizontal dynamic jacks 22 operate, forces are simultaneously applied from both the vertical and horizontal directions to the test specimen T, whose lower end is fixed to the excitation table 11 and whose upper end is fixed to the reaction beam 13. The response of the test specimen T to the forces applied to it in this manner is measured.

The reaction force detector 30 measures the response of the test specimen T when a force is applied to the test specimen T by multiple vertical dynamic jacks 21 and multiple horizontal dynamic jacks 22. One end 30a of the reaction force detector 30 is fixed to the reaction beam 13, and the other end 30b is fixed to the reaction wall 3. The reaction force detector 30 is equipped with a load cell 35, and the load in the detection axis direction of the reaction force detector 30 connecting the one end and the other end is detected by the load cell 35.
As shown in Figures 2 to 5, in this embodiment, the reaction force detector 30 is provided as a first reaction force detector 30A and a second reaction force detector 30B, and a third reaction force detector 30C and a fourth reaction force detector 30D.

The first reaction force detector 30A and the second reaction force detector 30B are provided between the reaction beam body 13a of the reaction beam 13 and the reaction wall 3. The first reaction force detector 30A and the second reaction force detector 30B are positioned on one side of the reaction beam 13 in the first direction D1. When viewed from above, the first reaction force detector 30A and the second reaction force detector 30B are provided so as to extend at a predetermined angle from the center of one side 13s (see Figure 2) of the reaction beam 13 that extends in the second direction D2, where the first reaction force detector 30A and the second reaction force detector 30B are not provided, toward the reaction wall 3. One end 30a of the first reaction force detector 30A and the second reaction force detector 30B are fixed to one side 13s of the reaction beam body 13a of the reaction beam 13, and the other end 30b is fixed to the reaction wall 3. In particular, as shown in Figure 5, one end 30a of the first reaction force detector 30A and the second reaction force detector 30B are connected to the reaction beam body 13a via a joint 30j, so that each of the first reaction force detector 30A and the second reaction force detector 30B can rotate freely around the horizontal axis about the joint 30j. The other end 30b of the first reaction force detector 30A and the second reaction force detector 30B are connected to the reaction wall 3 via a joint 30k, so that each of the first reaction force detector 30A and the second reaction force detector 30B can rotate freely around the horizontal axis about the joint 30k. As a result, the bending moment acting on the first reaction force detector 30A and the second reaction force detector 30B is reduced.
Furthermore, by arranging multiple reaction force detectors 30 radially from the center of the reaction beam 13 at a certain angle, the reaction force of the test specimen T can be measured directly without involving the deformation of the reaction beam 13, and the reaction force in the orthogonal direction can also be measured simultaneously. In addition, by installing multiple reaction force detectors 30 at both ends of the reaction beam 13, the rotational behavior of the reaction beam 13 in the planar direction can be constrained, and the couple can be measured.

The third reaction force detector 30C and the fourth reaction force detector 30D are positioned on the other side of the first direction D1 relative to the reaction beam 13, that is, on the side opposite to the side of the reaction beam 13 where the first reaction force detector 30A and the second reaction force detector 30B are provided. The third reaction force detector 30C is provided between the first beam member 13b of the reaction beam 13 and the reaction wall 3. The fourth reaction force detector 30D is provided between the second beam member 13c of the reaction beam 13 and the reaction wall 3. When viewed from above, the third reaction force detector 30C and the fourth reaction force detector 30D extend parallel to each other.
One end 30a of each of the third reaction force detector 30C and the fourth reaction force detector 30D is fixed to the same end on the first beam member 13b and the second beam member 13c in the first direction D1. In particular, as shown in Figure 5, one end 30a of each of the third reaction force detector 30C and the fourth reaction force detector 30D is connected to the first beam member 13b and the second beam member 13c via a joint 30m, so that each of the third reaction force detector 30C and the fourth reaction force detector 30D can rotate freely around a horizontal axis with respect to the joint 30m. The other end 30b of each of the third reaction force detector 30C and the fourth reaction force detector 30D is fixed to the reaction wall 3. The other ends 30b of the third reaction force detector 30C and the fourth reaction force detector 30D are connected to the reaction force wall 3 via a joint 30n, such that each of the third reaction force detector 30C and the fourth reaction force detector 30D can rotate freely around a horizontal axis with respect to the joint 30n. This reduces the bending moment acting on the third reaction force detector 30C and the fourth reaction force detector 30D.

Figure 8 shows the state in which a horizontal force is applied to the test specimen in the above-described load-bearing test apparatus.
In such a load-bearing test apparatus 10, the test specimen T is placed on the vibration table 11. The upper end of the test specimen T is fixed by a reaction beam 13. Forces are simultaneously applied to the vibration table 11 in the vertical and horizontal directions by vertical dynamic jacks 21 and horizontal dynamic jacks 22. For example, the vertical dynamic jacks 21 are applied to the vibration table 11 with a force equivalent to the building load that the test specimen T should support, and then the vertical dynamic jacks 21 and horizontal dynamic jacks 22 are operated to vibrate the vibration table 11 using the horizontal dynamic jacks 22. When a force is applied to the vibration table 11, a horizontal force Ft acts on the test specimen T, as shown in Figure 8. When a horizontal force Ft acts on the test specimen T, this horizontal force Ft is transmitted to the reaction beam 13 to which the upper end of the test specimen T is fixed.
The reaction beam 13 is supported from below by a rubber support member 15, the lower end 15e of which is provided so as not to move relative to the reaction floor 2. Furthermore, the reaction beam 13 is provided so as not to be displaced vertically relative to the support wall 14 and the reaction floor 2 by a tension member 17 into which a prestressing force has been introduced. For this reason, the reaction beam 13 will attempt to move horizontally due to the horizontal force transmitted to it.

Here, the first reaction force detector 30A and the second reaction force detector 30B are arranged such that, when viewed from above, one end 30a is fixed to the center of one side 13s of the reaction beam body 13a of the reaction beam 13, and they are positioned to spread out toward the reaction wall 3 at a predetermined angle, with the other end 30b fixed to the reaction wall 3. The third reaction force detector 30C and the fourth reaction force detector 30D are positioned on the side of the reaction beam 13 opposite to the side where the first reaction force detector 30A and the second reaction force detector 30B are located. One end 30a of the third reaction force detector 30C and the fourth reaction force detector 30D are fixed to the same end of the first beam member 13b and the second beam member 13c, respectively, with the other end 30b fixed to the reaction wall 3.
By providing the reaction force detectors 30 in this manner, rotation and translation of the reaction beam 13 are suppressed. For example, when the reaction beam 13 attempts to rotate, this is suppressed by a compressive force acting on either the first reaction force detector 30A or the second reaction force detector 30B, or by a compressive force acting on either the third reaction force detector 30C or the fourth reaction force detector 30D. Also, for example, when the reaction beam 13 attempts to move in the first direction D1, this is suppressed by a compressive force acting on either the first reaction force detector 30A and the second reaction force detector 30B, or the third reaction force detector 30C and the fourth reaction force detector 30D. Furthermore, for example, when the reaction beam 13 attempts to move in the second direction D2, this is suppressed by a compressive force acting on either the first reaction force detector 30A or the second reaction force detector 30B.
In this way, the movement of the reaction beam 13 is suppressed by the reaction force detector 30, and the horizontal force transmitted to the reaction beam 13 is transmitted to the reaction force detector 30 (first reaction force detector 30A, second reaction force detector 30B, third reaction force detector 30C, fourth reaction force detector 30D) as a compressive or tensile force. The majority of the horizontal force transmitted to the reaction beam 13 is detected as a first horizontal force F1 by a load cell 35 provided in the reaction force detector 30.
In practice, the first horizontal force F1 is detected by calculation based on the values detected by the load cells 35 of the first reaction force detector 30A, the second reaction force detector 30B, the third reaction force detector 30C, and the fourth reaction force detector 30D.

In this way, when the reaction force detector 30 detects the first horizontal force Ft, the reaction force detector 30 undergoes a slight compressive or elongative deformation due to the force acting on it, and the reaction beam 13 moves horizontally by the amount of this compression or elongation. Of the horizontal force transmitted to the test specimen T, the horizontal force consumed for the deformation of the reaction force detector 30 and the movement of the reaction beam 13 cannot be detected by the reaction force detector 30. In other words, the first horizontal force F1 detected by the reaction force detector 30 does not perfectly match the horizontal force acting on the test specimen T and transmitted to the reaction beam 13.
Here, the reaction beam 13 is supported from below by a rubber support member 15. The lower end 15e of the rubber support member 15 is provided so as to be immovable relative to the support wall 14 and the reaction floor 2, the rubber support member 15 deforms horizontally as the reaction beam 13 moves horizontally. As described above, the amount of compression and extension of the reaction force detector 30 is minute, on the order of a few millimeters, so even if the reaction beam 13 tries to move horizontally, the amount of movement will also be minute. The loading test device 10 detects this minute deformation of the rubber support member 15, for example, with a laser displacement meter (not shown) provided near the rubber support member 15, and thereby obtains the second horizontal force F2 transmitted by the deformation of the rubber support member 15.

Figure 9 shows an example of the relationship between the amount of deformation of the rubber support material and the second horizontal force generated by the deformation of the rubber support material.
As shown in Figure 9, the relationship between the deformation of the rubber support member 15 and the second horizontal force F2 is basically proportional if the deformation of the rubber support member 15 is small. Therefore, the relationship between the deformation of the rubber support member 15 and the second horizontal force F2, as shown in Figure 9, is determined in advance through prior member experiments, etc., to determine the relative horizontal deformation of the upper flange 15a and lower flange 15b of the rubber support member 15 when a horizontal force is applied. Then, when a horizontal force Ft is actually applied to the test specimen T from the vibration table 11, the deformation occurring in the rubber support member 15 is detected by a laser displacement meter, and the second horizontal force F2 borne by the rubber support member 15 is obtained based on the detected deformation.
In this way, the portion of the horizontal force transmitted to the test specimen T that was not measured as the first horizontal force F1 is obtained as the second horizontal force F2.
In the load testing device 10, the first horizontal force F1 and the second horizontal force F2 obtained as described above are added together, and the sum of these values is defined as the horizontal force Ft acting on the test specimen T.

The above-described load testing apparatus 10 is a load testing apparatus 10 that simultaneously applies forces from the vertical and horizontal directions to a test specimen T relating to a structure or a component of said structure, and measures the response of the test specimen T, comprising: a plurality of vertical dynamic jacks 21 provided above the reaction floor 2; an excitation table 11 installed above the vertical dynamic jacks 21 and on which the test specimen T is fixed to the upper surface; a reaction beam 13 that fixes the upper end of the test specimen T; and a plurality of horizontal dynamic jacks, one end 22a fixed to the reaction wall 3 and the other end 22b fixed to the excitation table 11. The apparatus comprises a buckle 22, a reaction force detector 30 with one end 30a fixed to the reaction beam 13 and the other end 30b fixed to the reaction wall 3, a rubber support member 15 with its lower end 15e fixed so as not to move relative to the reaction floor 2 and its upper end 15d joined to the reaction beam 13 to support the reaction beam 13, and a tension member 17 with one end 17a fixed to the reaction beam 13 and the other end 17b fixed to the reaction floor 2. The horizontal force Ft acting on the test specimen T is the sum of a first horizontal force F1 measured by the reaction force detector 30 and a second horizontal force F2 transmitted by the deformation of the rubber support member 15.
In this configuration, the test specimen T is placed on the excitation table 11. The upper end of the test specimen T is fixed by the reaction beam 13. When the excitation table 11 is moved by the vertical dynamic jack 21 and the horizontal dynamic jack 22, a horizontal force acts on the test specimen T in addition to the vertical force. The horizontal force Ft acting on the test specimen T is transmitted as a compressive or tensile force to the reaction force detector 30, which is provided between the reaction wall 3 and the reaction beam 13, via the reaction beam 13. Here, the reaction beam 13 is supported from below by a rubber support member 15 whose lower end 15e is fixed so as to be immovable relative to the reaction floor 2, and the reaction beam 13 is movable relative to the reaction floor 2, so the transmission of this horizontal force is not hindered by the rubber support member 15. The horizontal force transmitted to the reaction force detector 30 in this way is measured as the first horizontal force F1.
When the reaction force detector 30 detects the first horizontal force F1 in the manner described above, the reaction force detector 30 undergoes a slight compressive or elongative deformation due to the influence of the horizontal force transmitted to it, and the reaction beam 13 moves horizontally by the amount of this compression or elongation. Of the horizontal force transmitted to the test specimen T, the horizontal force consumed for the deformation of the reaction force detector 30 and the movement of the reaction beam 13 cannot be measured as the first horizontal force F1 by the reaction force detector 30. Here, the amount of compression and elongation of the reaction force detector 30 is minute, and the amount of movement of the reaction beam 13 and the amount of deformation of the rubber support material 15 that accompany it are also minute. The relationship between the amount of deformation of the rubber support material 15 and the horizontal force acting on the rubber support material 15 is basically proportional in the initial deformation stage when the amount of deformation is minute. Therefore, by understanding this relationship in advance, it is possible to identify the portion of the horizontal force Ft transmitted to the reaction beam 13 that is not measured by the reaction force detector 30 as the first horizontal force F1, based on the amount of deformation of the rubber support material 15, as the second horizontal force F2, i.e., the component transmitted by the deformation of the rubber support material 15.
By adding the first horizontal force F1, measured by the reaction force detector 30, and the second horizontal force F2, transmitted by the deformation of the rubber support material 15, the horizontal force Ft acting on the test specimen T can be accurately detected.
Here, the first and second horizontal forces F1 and F2 are not measured with respect to the excitation table 11 which is directly moved by the horizontal dynamic jack 22. Therefore, the first and second horizontal forces F1 and F2 do not include the inertial force when moving the excitation table 11 or the frictional force acting between the excitation table 11 and the members supporting it (base 11a and bearing 11c).
Furthermore, since the reaction beam 13 is connected to the reaction floor 2 by a tensioning member 17, the vertical displacement of the reaction beam 13 is suppressed, while it is not rigidly constrained in the horizontal direction. Therefore, the horizontal force acting on the rubber support member 15 is less likely to be transmitted vertically through the tensioning member 17. This improves the accuracy of horizontal force measurement.
The combined effect of these factors allows for the accurate detection of the horizontal force acting on the test specimen T.
Furthermore, in the above configuration, when supporting the reaction beam 13, it is basically sufficient to provide rubber support material 15 and tensioning material 17, resulting in a simpler structure.
Furthermore, in the configuration described above, since it is not affected by frictional and inertial forces, it is possible to detect horizontal forces in real time.
As a result, it becomes possible to provide a force testing device 10 that can accurately and in real time detect the horizontal force Ft acting on the test specimen T, and can be realized with a simple structure.

Furthermore, the rubber support material 15 is either a single-layer rubber bearing or a laminated rubber bearing consisting of multiple layers.
With this configuration, the rubber support material 15, which is a single-layer rubber bearing or a laminated rubber bearing, has high vertical rigidity, and vertical deformation is suppressed. Therefore, when a horizontal force acts on the rubber support material, vertical deformation of the rubber support material 15 is suppressed, and the rubber support material 15 can deform smoothly in the horizontal direction by the amount of the applied horizontal force. Thus, the second horizontal force F2 can be accurately determined.

Furthermore, multiple rubber support members 15 are installed, and each rubber support member 15 is restrained under a predetermined compressive stress by a prestressing force from tensioning members 17 provided at adjacent positions.
With this configuration, the prestressing force of the tensioning member 17 restrains the rubber support member 15, which has high vertical rigidity, under compressive stress. This suppresses the vertical displacement of the rubber support member 15 while minimizing its dependence on surface pressure. As a result, the second horizontal force F2 caused by the horizontal deformation of the rubber support member 15 can be measured stably.
Specifically, in the loading test apparatus, the vertical direction is constrained by high vertical stiffness provided by the rubber support material and high prestress force using PC steel strands, while the horizontal direction is constrained by low elastic stiffness (for example, about 1/3000 of the vertical stiffness) to allow deformation of a few millimeters or less. This allows most of the horizontal reaction force to be borne by the reaction force detector, and the second horizontal force transmitted by the deformation of the rubber support material is calculated by multiplying the total stiffness of the rubber support material by the minute deformation that occurs in this part. As a result, the horizontal load acting on the test specimen can be accurately and immediately measured as the sum of the second horizontal force generated in the rubber support material and the first horizontal force of the reaction force detector.

Furthermore, multiple reaction force detectors 30 are arranged between the reaction beam 13 and the reaction wall 3. Each reaction force detector 30 has a built-in load cell 35 and is provided with joints 30j, 30k, 30m, and 30n at both ends to reduce bending moment.
With this configuration, a load cell 35 capable of accurately measuring axial force is built into the reaction force detector 30, and joints 30j, 30k, 30m, and 30n that reduce bending moment are provided at both ends of the reaction force detector 30, thereby suppressing the generation of bending moment on the load cell 35 due to the displacement of the reaction beam 13.

Furthermore, the other end 17b of the tensioning member 17 is fixed at a position below the reaction beam 13 at a predetermined distance or more, and the space between one end 17a and the other end 17b of the tensioning member 17 is inserted into a pipe 17p, and the inner diameter D of the pipe 17p is large enough to allow the horizontal movement of the tensioning member 17 due to the horizontal deformation of the reaction beam 13.
With this configuration, the geometric horizontal stiffness acting on the tensioning member 17 is reduced, making it possible to move the reaction beam 13 in the horizontal direction while allowing the displacement of the tensioning member 17 associated with this movement.

Furthermore, the reaction force detector 30 comprises a first reaction force detector 30A and a second reaction force detector 30B. When viewed from above, one end 30a of each of the first reaction force detector 30A and the second reaction force detector 30B is fixed to the center of one side 13s of the reaction beam 13, and is provided to spread out toward the reaction wall 3 at a predetermined angle, with the other end 30b fixed to the reaction wall 3.
With this configuration, by arranging the first reaction force detector 30A and the second reaction force detector 30B so that they spread out at a predetermined angle from the center of one side 13s of the reaction beam 13 toward the reaction wall 3, the reaction force of the test specimen T can be measured directly without involving the deformation of the reaction beam 13, and the reaction force in the orthogonal direction can also be measured simultaneously.

Furthermore, the reaction beam 13 comprises a first beam member 13b and a second beam member 13c, which are provided parallel to each other, and the reaction force detector 30 comprises a third reaction force detector 30C and a fourth reaction force detector 30D. The third reaction force detector 30C and the fourth reaction force detector 30D are positioned on the side of the reaction beam 13 opposite to the side of the reaction beam 13 where the first reaction force detector 30A and the second reaction force detector 30B are provided, and one end 30a of the third reaction force detector 30C and the fourth reaction force detector 30D are fixed to the same end of the first beam member 13b and the second beam member 13c, respectively.
With this configuration, by installing the third reaction force detector 30C and the fourth reaction force detector 30D on the same end of the first beam member 13b and the second beam member 13c, it becomes possible to restrain the rotational behavior of the reaction beam 13 in the planar direction and measure the couple.

Furthermore, the load testing apparatus of the present invention constructs a load testing system that directly measures the horizontal force acting on the test specimen as the sum of a first horizontal force measured by a reaction force detector and a second horizontal force transmitted by the deformation of the rubber support material. This makes it possible to acquire a highly accurate reaction force time history in real time, free from the interference of frictional and inertial forces. By using this load testing system, response values are obtained simultaneously with the application of load to the test specimen, and these response values can be instantaneously captured to estimate the response of the structure with high accuracy.
Furthermore, the force testing apparatus of the present invention has the following features.
In a load-bearing test apparatus, the tensioning member is fixed at the other end relative to the reaction beam as far away from the reaction wall as possible (vertically downward), allowing for horizontal movement of the tensioning member due to the horizontal deformation of the rubber support member, and the tensioning member is enclosed in a tube of a specific inner diameter.
The load testing apparatus is characterized in that the reaction force detector or a part thereof has two reaction force detectors, one end of which is fixed to the center of the reaction beam on which the test specimen is installed, and the other end of which is spread out at a certain angle and fixed to the reaction wall.
The load testing apparatus is characterized in that the reaction force detector or a part thereof has two reaction force detectors, one end of which is fixed to the reaction beam on which the test specimen is installed, and the other end of which is fixed to the reaction wall.

(Variations of the embodiment)
It should be noted that the force testing apparatus of the present invention is not limited to the embodiments described above with reference to the drawings, and various modifications are conceivable within its technical scope.
For example, in the above embodiment, the force testing device 10 is provided with a horizontal dynamic jack 22 that vibrates the vibration table 11 in a horizontal direction along the first direction D1, and a horizontal dynamic jack 22 that applies a vertical force to the vibration table 11, but it is not limited to this. In addition, the force testing device may be configured to further include another horizontal dynamic jack that vibrates the vibration table 11 in a horizontal direction along the second direction D2, thereby realizing a configuration in which forces are applied simultaneously to three axes so as to vibrate the vibration table 11 in two horizontal directions, the first direction D1 and the second direction D2, while applying a vertical force.
In addition to the above, it is possible to select or replace the configurations listed in the above embodiments, or to change them to other configurations as appropriate, as long as it does not deviate from the spirit of the present invention.

2. Reaction floor 22a (one end) 3. Reaction wall 22b (other end) 10. Loading test device (triaxial loading test device or biaxial loading test device)
11 Vibration table 30 Reaction force detector 13 Reaction beam 30a one end 15 Rubber support member 30b other end 15d Upper end 30j, 30k, 30m, 30n Joint member 15e Lower end 35 Load cell 17 Tensioner D Inner diameter 17a one end F1 First horizontal force 17b other end F2 Second horizontal force 21 Vertical dynamic jack Ft Horizontal force 22 Horizontal dynamic jack T Test specimen

Claims (4)

A force testing apparatus for measuring the response of a test specimen to a structure or a component of said structure, by simultaneously applying forces from the vertical and horizontal directions to said test specimen,
Multiple vertical dynamic jacks are installed above the reaction floor,
An excitation table is installed above the aforementioned vertical dynamic jack, and the test specimen is fixed to its upper surface.
A reaction beam that fixes the upper end of the test specimen,
Multiple horizontal dynamic jacks, one end of which is fixed to the reaction wall and the other end of which is fixed to the vibration table,
A reaction force detector, with one end fixed to the reaction beam and the other end fixed to the reaction wall,
A rubber support member whose lower end is provided so as not to move relative to the reaction floor, and whose upper end is joined to the reaction beam to support the reaction beam,
A tensioning member, with one end fixed to the reaction beam and the other end fixed to the reaction floor,
Equipped with,
The load testing apparatus is characterized in that the horizontal force acting on the test specimen is the sum of a first horizontal force measured by the reaction force detector and a second horizontal force transmitted by the deformation of the rubber support material. The load testing apparatus according to claim 1, characterized in that the rubber support material is a single-layer rubber bearing or a laminated rubber bearing consisting of multiple layers. The loading test apparatus according to claim 1 or 2, characterized in that multiple rubber support members are installed, and each of the rubber support members is restrained under a predetermined compressive stress by a prestressing force from the tensioning member provided at an adjacent position. The loading test apparatus according to claim 1 or 2, characterized in that a plurality of reaction force detectors are arranged between the reaction beam and the reaction wall, each reaction force detector has a built-in load cell, and joints for reducing bending moment are provided at both ends.