Wood material fastener shear test device and test method thereof

Abstract

The invention belongs to the technical field of fastener test, and discloses a wood material fastener shear test device, which comprises an upper clamp chuck, an upper clamp top plate, a fixed clamping plate, a movable clamping plate, a fastening bolt, a lower clamp chuck, a lower clamp top plate, a lower clamp web plate, a lower clamp bottom plate, a pressing strip, a long fixing bolt, a covering plate and a dimension material. According to the testing device, the fastener is sheared by using the base material instead of being sheared by directly using a clamp, so that the testing device is more suitable for the real application scene of the wood fastener, the testing result is more accurate, and the clamp can be protected. The test device can adapt to different shearing surfaces, different loading directions, different fastener types, different covering plate materials and thicknesses, and different specifications and sizes. And the testing device can be changed into a three-shear or multi-shear testing device through simple modification, and can be used for carrying out three-shear or multi-shear tests on wood fasteners, so that the requirements of various engineering practices are met.

Description

Technical Field

[0001] The present invention belongs to the technical field of fastener testing, and particularly relates to a testing device and a testing method for nail connection testing of light wood structure shear walls, which are configured on a mechanical testing machine. Background Art

[0002] A light wood shear wall is composed of a wall frame made of dimension lumber and a sheathing panel connected by nails. The lateral stiffness and lateral load-bearing capacity of the light wood shear wall are mainly determined by the mechanical properties of the nail connection between the dimension lumber of the wall frame and the sheathing panel. Compared with the single-shear nail connection formed between the dimension lumber and the sheathing panel of a conventional light wood shear wall (the composition is, in sequence, an inner sheathing panel - stud - outer sheathing panel), the dimension lumber and the sheathing panel of a plywood shear wall (the composition is, in sequence, an inner sheathing panel - stud - middle sheathing panel - stud - outer sheathing panel) form a double-shear or even triple-shear nail connection, which greatly improves the lateral force resistance performance of the light wood shear wall.

[0003] To improve the lateral force resistance performance of light wood shear walls, with the progress of material processing technology, dimension lumber of different materials (bamboo glued lumber, LVL), sheathing panels (OSB boards, straw boards, bamboo glue boards, etc.) and nails (round nails, twist nails, and self-tapping screws) are used in light wood shear walls. In addition to the material type, the material size, loading direction (longitudinal and transverse) and nail arrangement (spacing and end distance) are also crucial for the lateral force resistance performance of light wood shear walls. By conducting nail connection joint tests and preliminarily analyzing their mechanical properties such as strength, stiffness, ductility, and energy dissipation, not only can materials be saved, but it also has great significance for the overall lateral force analysis of the wall. In addition, the mechanical properties of the nail connection joint are also essential data in the process of finite element analysis of the wall. In existing nail connection joint tests, generally, only the mechanical property tests of the standard single-shear nail connection in conventional light wood shear walls are carried out, while the double-shear (triple-shear) nail joint tests in plywood wood shear wall structures are rarely carried out. In addition, due to the large shear strength of the nail connection joint, the existing nail connection joint test device is complex in design and insufficient in bearing capacity; (1) obvious deformation occurs in the test device itself during the test process; (2) it is easy to cause the connection between the sheathing panel and the fixture to fail prior to the nail connection joint during the test process; (3) the complex device cannot effectively carry out a large number of repeated tests. The above three problems all lead to the inability to effectively test the force-displacement parameters of the nail connection joint.

[0004] Therefore, there is an urgent need to design a wood material fastener shear test device with high strength, simple structure, and capable of simultaneously realizing single-shear, double-shear, and even multi-shear. Summary of the Invention

[0005] The present invention aims to solve at least one of the technical problems in the related art to a certain extent. For this purpose, the present invention provides a test device that can be used in conjunction with a mechanical testing machine, is used to test the shear performance of the nail connection joints of balsa wood shear walls, and can be applied to specimens of different specifications and different shear surfaces.

[0006] To achieve the above object, the present invention provides a shear test device for wood material fasteners, including an upper fixture and a lower fixture; The upper fixture includes an upper fixture top plate and fastening bolts. An upper fixture chuck is fixedly connected to the upper side of the upper fixture top plate. A fixed clamping plate and a movable clamping plate parallel to the fixed clamping plate are provided on the lower side of the upper fixture top plate. A top plate sliding groove is formed on the upper fixture top plate. The movable clamping plate is slidably connected to the upper fixture top plate through the top plate sliding groove. Multiple groups of corresponding threaded through holes are formed on the fixed clamping plate and the movable clamping plate. One group of threaded through holes corresponds to one fastening bolt; The lower fixture includes a lower fixture top plate, two pressing strips, and four long fixing bolts. Lower fixture webs are provided at both ends of the lower side of the lower fixture top plate. The lower ends of the two lower fixture webs are connected to the same lower fixture bottom plate. A lower fixture chuck is fixedly connected to the lower side of the lower fixture bottom plate. Edge bolt holes are formed at the four end corners of the lower fixture top plate. One pressing strip corresponds to two edge bolt holes and two long fixing bolts. The pressing strip is installed on the lower fixture top plate through the two edge bolt holes and the two long fixing bolts. The two pressing strips are perpendicular to the fixed clamping plate. A long groove is formed in the middle of the lower fixture top plate corresponding to the gap between the fixed clamping plate and the movable clamping plate; The shear test device for wood material fasteners is connected to a universal testing machine through the upper fixture chuck and the lower fixture chuck.

[0007] Further, four groups of threaded through holes are formed on the fixed clamping plate and the movable clamping plate, and the four groups of threaded through holes are respectively located at the four end corners of the fixed clamping plate and the movable clamping plate.

[0008] Further, four central bolt holes are also formed on the lower fixture top plate, and the four central bolt holes can also be threadedly connected to the long fixing bolts.

[0009] With such a structural design, when the specimen to be tested is short or placed longitudinally, the long fixing bolts and the pressing strips can be installed using the central bolt holes, and the applicability is stronger.

[0010] The present invention also provides a fastener shear test method using the above shear test device for wood material fasteners, including the following steps: S1. Pass the fastener to be sheared and tested through the sheathing and the dimension lumber to form a specimen to be tested; S2. Place the facing panel of the specimen to be tested between the fixed clamping plate and the movable clamping plate of the upper fixture. Adjust the movable clamping plate until both the movable clamping plate and the fixed clamping plate are in close contact with the facing panel of the specimen to be tested. Then, fix the movable clamping plate and the facing panel to the fixed clamping plate with four horizontally arranged fixing bolts. S3. Install the upper fixture and the lower fixture on the universal testing machine through the upper fixture chuck and the lower fixture chuck respectively. Then, manually control the upper fixture on the universal testing machine to move downward until the lower end of the lumber of the specimen to be tested clamped by the upper fixture contacts the top plate of the lower fixture. S4. Place the pressure bar on the top of the lumber of the specimen to be tested. Then, pass a long fixing bolt through the corresponding bolt holes of the pressure bar and the top plate of the lower fixture, and tighten the long fixing bolt to fix the lumber of the specimen to be tested on the lower fixture. S5. Drive the upper fixture to move downward at a set rate through the universal testing machine to apply a load. S6. Record the displacement and load data of the upper fixture of the loading testing machine to obtain the shear load-displacement curve of the wood material fastener.

[0011] Furthermore, the fasteners in step S1 include round nails, twist nails, self-tapping screws and bolts.

[0012] Furthermore, the specimens to be tested in step S1 are divided into single-shear specimens to be tested, double-shear specimens to be tested and multi-shear specimens to be tested according to the shear plane; The single-shear specimen to be tested refers to the specimen to be tested in which the facing panel and the lumber are connected alternately with fasteners and there is only one shear plane; The double-shear specimen to be tested refers to the specimen to be tested in which the facing panel and the lumber are connected alternately with fasteners and there are only two shear planes; The multi-shear specimen to be tested refers to the specimen to be tested in which the facing panel and the lumber are connected alternately with fasteners and there are multiple shear planes.

[0013] Furthermore, the specimens to be tested in step S1 are divided into cross-grain specimens to be tested and longitudinal-grain specimens to be tested according to the loading direction; The cross-grain specimen to be tested refers to the specimen to be tested in which the lumber in the specimen to be tested is placed horizontally; The longitudinal-grain specimen to be tested refers to the specimen to be tested in which the lumber in the specimen to be tested is placed longitudinally.

[0014] Beneficial effects: The test device of the present invention is provided with a nail-connected facing panel clamping device and a lumber clamping device, which can flexibly adjust the distance according to requirements and can be used for fixing facing panels of different thicknesses and different materials. At the same time, the lumber of the specimen to be tested is firmly fixed to the lower fixture by using 4 long fixing bolts, which can further enhance the stability of the specimen to be tested and enable the device to have both monotonic shear and cyclic shear functions.

[0015] The test device of the present invention uses the base material to perform longitudinal and transverse shearing on the fastener, rather than directly using a fixture to perform shearing on it. This is more in line with the actual application scenario of the fastener, making the test results more accurate and protecting the fixture itself from being easily damaged. At the same time, the double-shear test device can be simply modified into a triple-shear or multi-shear test device, and can perform triple-shear or multi-shear tests on fasteners to meet the needs of various engineering practices.

[0016] Other advantages, objectives and features of the present invention will be described to some extent in the subsequent specification, and to some extent, based on the study of the following text, will be obvious to those skilled in the art or can be taught from the practice of the present invention. The objectives and other advantages of the present invention can be achieved and obtained through the following specification. Brief Description of the Drawings

[0017] Figure 1 It is a schematic structural diagram of the shearing test device for wood fasteners in Embodiment 1; Figure 2 It is a left view of the shearing test device for wood fasteners in Embodiment 1; Figure 3 It is a schematic diagram of the upper fixture of the shearing test device for wood fasteners in Embodiment 1; Figure 4 It is a schematic diagram of the lower fixture of the shearing test device for wood fasteners in Embodiment 1; Figure 5 It is a schematic diagram of the top plate of the upper fixture of the shearing test device for wood fasteners in Embodiment 1; Figure 6 It is a schematic diagram of the movable clamping plate of the upper fixture of the shearing test device for wood fasteners in Embodiment 1; Figure 7 It is a schematic diagram of the transverse double-shear of the shearing test device for wood fasteners in Embodiment 1; Figure 8 It is a left view of the transverse double-shear of the shearing test device for wood fasteners in Embodiment 1; Figure 9 It is a schematic diagram of the longitudinal double-shear of the shearing test device for wood fasteners in Embodiment 2; Figure 10 It is a left view of the longitudinal double-shear of the shearing test device for wood fasteners in Embodiment 2; Figure 11 It is a schematic diagram of the transverse single-shear of the shearing test device for wood fasteners in Embodiment 3; Figure 12 It is a schematic diagram of the longitudinal single-shear of the shearing test device for wood fasteners in Embodiment 4; Figure 13Schematic diagram of cross-grain three-shear test for the wood material fastener shear test device in Example 5; Figure 14 Schematic diagram of cross-grain four-shear test for the wood material fastener shear test device in Example 6; Figure 15 Test result diagram of cross-grain double-shear test for the wood material fastener shear test device in Example 1; The reference signs in the figure are as follows: upper fixture chuck 1, upper fixture top plate 2, top plate chute 201, fixed clamping plate 3, movable clamping plate 4, fastening bolt 5, lower fixture chuck 6, lower fixture top plate 7, edge bolt hole 701, center bolt hole 702, long slot 703, lower fixture web 8, lower fixture bottom plate 9, pressing strip 10, long fixing bolt 11, overlay panel 12, dimension lumber 13. Detailed implementation manners

[0018] To make the technical solutions, advantages and objectives of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the described embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of this application. Example 1

[0019] As Figures 1 - 6 shown, this embodiment provides a wood material fastener shear test device, including an upper fixture and a lower fixture; The upper fixture includes an upper fixture top plate 2 and a fastening bolt 5. An upper fixture chuck 1 detachably connected to a universal testing machine is installed on the upper side of the upper fixture top plate 2. A fixed clamping plate 3 and a movable clamping plate 4 parallel to the fixed clamping plate 3 are provided on the lower side of the upper fixture top plate 2. The fixed clamping plate 3 is fixedly connected to the upper fixture top plate 2. A top plate chute 201 is provided on the upper fixture top plate 2. The movable clamping plate 4 is slidably connected to the upper fixture top plate 2 through the top plate chute 201. A plurality of groups of corresponding threaded through holes are provided on the fixed clamping plate 3 and the movable clamping plate 4. One group of threaded through holes corresponds to one fastening bolt 5. In this way, the stability is stronger, and it can adapt to overlay panels 12 of different materials; The lower fixture includes a lower fixture top plate 7, two pressing bars 10 and four long fixing bolts 11. At both ends of the lower side of the lower fixture top plate 7, lower fixture webs 8 are fixedly connected. The lower ends of the two lower fixture webs 8 are connected to the same lower fixture bottom plate 9. A lower fixture chuck 6 detachably connected to a universal testing machine is fixedly connected to the lower side of the lower fixture bottom plate 9. Edge bolt holes 701 are provided at the four corner ends of the lower fixture top plate 7. One pressing bar 10 corresponds to two edge bolt holes 701 and two long fixing bolts 11. The pressing bar 10 is installed on the lower fixture top plate 7 through the two edge bolt holes 701 and the two long fixing bolts 11. The two pressing bars 10 are both perpendicular to the fixed clamping plate 3. A long slot 703 is provided at the middle position of the lower fixture top plate 7 corresponding to the gap between the fixed clamping plate 3 and the movable clamping plate 4; The wood material fastener shear test device is connected to a universal testing machine through an upper fixture chuck 1 and a lower fixture chuck 6.

[0020] As a preference of this embodiment, four groups of threaded through holes are provided on the fixed clamping plate 3 and the movable clamping plate 4, and the four groups of threaded through holes are respectively located at the four corner ends of the fixed clamping plate 3 and the movable clamping plate 4.

[0021] As a preference of this embodiment, four central bolt holes 702 are further provided on the lower fixture top plate 7, and the four central bolt holes 702 can also be threadedly connected to the long fixing bolts 11.

[0022] This embodiment also provides a fastener shear test method using the above wood material fastener shear test device, including the following steps: S1. Pass the fastener to be shear-tested through the overlay panel 12 and the dimension lumber 13 to form a test specimen to be tested; Among them, the fasteners include round nails, twist nails, self-tapping screws and bolts; The test specimens to be tested are divided into single-shear test specimens, double-shear test specimens and multi-shear test specimens according to the shear plane; A single-shear test specimen refers to a test specimen in which the overlay panel 12 and the dimension lumber 13 are staggeredly connected by fasteners and there is only one shear plane; A double-shear test specimen refers to a test specimen in which the overlay panel 12 and the dimension lumber 13 are staggeredly connected by fasteners and there are only two shear planes; A multi-shear test specimen refers to a test specimen in which the overlay panel 12 and the dimension lumber 13 are staggeredly connected by fasteners and there are multiple shear planes; The test specimens to be tested are divided into cross-grain test specimens and longitudinal-cross-grain test specimens according to the loading direction; A cross-grain test specimen refers to a test specimen in which the dimension lumber 13 in the test sample is placed horizontally; A longitudinal-grain test specimen refers to a test specimen in which the dimension lumber 13 in the test sample is placed longitudinally.

[0023] Such as Figure 7 AndFigure 8 As shown, the test specimen in this embodiment is a cross-grain double-shear test specimen; S2. Place the facing panel 12 of the test specimen between the fixed clamping plate 3 and the movable clamping plate 4 of the upper fixture. Adjust the movable clamping plate 4 until both the movable clamping plate 4 and the fixed clamping plate 3 are in close contact with the facing panel 12 of the test specimen. Then, use four horizontally arranged fixing bolts to fix the movable clamping plate 4 and the facing panel 12 to the fixed clamping plate 3; The movable clamping plate 4 moves in cooperation within the chute of the upper fixture top plate 2, which can adapt to facing panels 12 of different thicknesses; S3. Install the upper fixture and the lower fixture on the universal testing machine through the upper fixture chuck 1 and the lower fixture chuck 6 respectively. Then, manually control the upper fixture on the universal testing machine to slowly move downward until the lower end of the lumber 13 of the test specimen clamped by the upper fixture contacts the lower fixture top plate 7; Among them, it is necessary to ensure that the facing panel 12 of the test specimen is at the center position of the long groove 703 of the lower fixture top plate 7; With such a structural design, when the test specimen uses lumbers 13 of different sizes, by adjusting the positions of the pressure bar 10 and the long fixing bolt 11, and combining the pressure bar 10 and the long fixing bolt 11 to fix the test specimen and the lower fixture; S4. Place the pressure bar 10 on the top of the lumber 13 of the test specimen. Then, pass the long fixing bolt 11 through the corresponding bolt holes of the pressure bar 10 and the lower fixture top plate 7, and tighten the long fixing bolt 11 to fix the lumber 13 of the test specimen to the lower fixture; S5. Drive the upper fixture to move downward at a set rate through the universal testing machine to apply a load; S6. Record the displacement and load data of the upper fixture of the loading testing machine to obtain the shear load-displacement curve of the wood material fastener. The shear load-displacement curve of the cross-grain double-shear test specimen in this embodiment is as Figure 15 shown. Embodiment 2

[0024] As Figure 9 and Figure 10 shown, this embodiment provides a shear test device for wood material fasteners and its test method. The test device and test method in this embodiment are the same as those in Embodiment 1. The difference is that the test specimen in this embodiment is a longitudinal-grain double-shear test specimen. Embodiment 3

[0025] As Figure 11 shown, this embodiment provides a shear test device for wood material fasteners and its test method. The test device and test method in this embodiment are the same as those in Embodiment 1. The difference is that the test specimen in this embodiment is a cross-grain single-shear test specimen. Example 4

[0026] As Figure 12 shown, this embodiment provides a shear test device for wood material fasteners and its test method. Both the test device and the test method of this embodiment are the same as those of Embodiment 1. The difference is that the test specimen in this embodiment is a longitudinal single-shear test specimen. Example 5

[0027] As Figure 13 shown, this embodiment provides a shear test device for wood material fasteners and its test method. Both the test device and the test method of this embodiment are the same as those of Embodiment 1. The difference is that the test specimen in this embodiment is a cross-grain triple-shear test specimen. Example 6

[0028] As Figure 14 shown, this embodiment provides a shear test device for wood material fasteners and its test method. Both the test device and the test method of this embodiment are the same as those of Embodiment 1. The difference is that the test specimen in this embodiment is a cross-grain quadruple-shear test specimen.

[0029] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the present technical solution, and they should all be covered by the protection scope of the present invention.

Claims

1. A shear test device for wood material fasteners, characterized in that: It includes an upper fixture and a lower fixture; The upper fixture includes an upper fixture top plate (2) and fastening bolts (5). An upper fixture chuck (1) is fixedly connected to the upper side of the upper fixture top plate (2). A fixed clamping plate (3) and a movable clamping plate (4) parallel to the fixed clamping plate (3) are provided on the lower side of the upper fixture top plate (2). A top plate sliding groove (201) is formed on the upper fixture top plate (2). The movable clamping plate (4) is slidably connected to the upper fixture top plate (2) through the top plate sliding groove (201). A plurality of groups of corresponding threaded through holes are formed on the fixed clamping plate (3) and the movable clamping plate (4). One group of threaded through holes corresponds to one fastening bolt (5); The lower fixture includes a lower fixture top plate (7), two pressing strips (10) and four long fixing bolts (11). Lower fixture webs (8) are arranged at both ends of the lower side of the lower fixture top plate (7). The lower ends of the two lower fixture webs (8) are connected to the same lower fixture bottom plate (9). A lower fixture chuck (6) is fixedly connected to the lower side of the lower fixture bottom plate (9). Edge bolt holes (701) are formed at the four end corners of the lower fixture top plate (7). One pressing strip (10) corresponds to two edge bolt holes (701) and two long fixing bolts (11). The pressing strip (10) is installed on the lower fixture top plate (7) through the two edge bolt holes (701) and the two long fixing bolts (11). The two pressing strips (10) are perpendicular to the fixed clamping plate (3). A long groove (703) is formed in the middle of the lower fixture top plate (7) corresponding to the gap between the fixed clamping plate (3) and the movable clamping plate (4); The wood material fastener shear test device is connected to a universal testing machine through the upper fixture chuck (1) and the lower fixture chuck (6).

2. The shear test device for a wooden material fastener according to claim 1, characterized in that: Four groups of threaded through holes are formed on the fixed clamping plate (3) and the movable clamping plate (4), and the four groups of threaded through holes are respectively located at the four end corners of the fixed clamping plate (3) and the movable clamping plate (4).

3. The shear test device for a wooden material fastener according to claim 2, wherein: Four central bolt holes (702) are also formed on the lower fixture top plate (7), and the four central bolt holes (702) can also be threadedly connected to the long fixing bolts (11).

4. A fastener shear test method using the wood material fastener shear test device according to any one of claims 1 to 3, characterized in that, It includes the following steps: S1. Pass the fastener to be shear-tested through the overlay panel (12) and the dimension lumber (13) to form a test piece to be tested; S2. Place the overlay panel (12) of the test piece to be tested between the fixed clamping plate (3) and the movable clamping plate (4) of the upper fixture. Adjust the movable clamping plate (4) until both the movable clamping plate (4) and the fixed clamping plate (3) are in close contact with the overlay panel (12) of the test piece to be tested. Then fix the movable clamping plate (4) and the overlay panel (12) to the fixed clamping plate (3) with four horizontally arranged fixing bolts (5); S3. Install the upper fixture and the lower fixture on the universal testing machine respectively through the upper fixture chuck (1) and the lower fixture chuck (6). Then manually control the upper fixture on the universal testing machine to move downward until the lower end of the dimension lumber (13) of the test piece clamped by the upper fixture contacts the lower fixture top plate (7); S4. Place the batten (10) on top of the lumber (13) of the specimen to be tested, then pass the long fixing bolt (11) through the corresponding bolt holes of the batten (10) and the lower fixture top plate (7), and tighten the long fixing bolt (11) to fix the lumber (13) of the specimen to be tested on the lower fixture; S5. Drive the upper fixture of the universal testing machine to move downward at a set rate to apply a load; S6. Record the displacement and load data of the upper fixture of the loading testing machine to obtain the shear load-displacement curve of the wood material fastener.

5. A method for shear test of a wood material fastener according to claim 4, characterized in that: The fasteners in step S1 include round nails, twist nails, self-tapping screws and bolts.

6. A method for shear test of a wood material fastener according to claim 5, characterized in that: The specimens to be tested in step S1 are divided into single-shear specimens to be tested, double-shear specimens to be tested and multi-shear specimens to be tested according to the shear plane; The single-shear specimen to be tested refers to the specimen to be tested in which the sheathing (12) and the lumber (13) are staggered and connected with fasteners and there is only one shear plane; The double-shear specimen to be tested refers to the specimen to be tested in which the sheathing (12) and the lumber (13) are staggered and connected with fasteners and there are only two shear planes; The multi-shear specimen to be tested refers to the specimen to be tested in which the sheathing (12) and the lumber (13) are staggered and connected with fasteners and there are multiple shear planes.

7. A method for shear test of a wooden material fastener according to claim 6, characterized in that: The specimens to be tested in step S1 are divided into cross-grain specimens to be tested and longitudinal-grain specimens to be tested according to the loading direction; The cross-grain specimen to be tested refers to the specimen to be tested in which the lumber (13) in the specimen to be tested is placed horizontally; The longitudinal-grain specimen to be tested refers to the specimen to be tested in which the lumber (13) in the specimen to be tested is placed longitudinally.

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