A fixing part and a stress testing device and a testing method using the same

Abstract

The present invention discloses a fixing piece and a stress testing device and a testing method using the same. The fixing piece is used for fixing a concrete strain gauge and comprises a fixing part. The fixing part has a first side surface and a second side surface which are arranged opposite to each other. The first side surface has a first fixing structure which is suitable for clamping the concrete strain gauge so that the concrete strain gauge is fixed to the first side surface of the fixing part along a first direction; the second side surface has a second fixing structure which is suitable for clamping the concrete strain gauge so that the concrete strain gauge is fixed to the second side surface of the fixing part along a second direction; the first direction and the second direction form an angle so that two concrete strain gauges are cross-clamped to the fixing piece.

Description

Technical Field

[0001] The invention relates to the field of concrete performance testing, and in particular to a fixing component and a stress testing device and a testing method using the fixing component. Background Art

[0002] In prefabricated reinforced concrete structures, concrete composite components have the dual advantages of prefabricated structures and cast-in-place concrete structures, and are widely used in today's construction projects. Generally, concrete composite components can be divided into prefabricated parts and cast-in-place parts. Taking concrete composite beams or composite slabs as an example, the bottom is generally prefabricated and the upper part is cast-in-place.

[0003] The overall working performance of concrete composite components is directly related to the stress characteristics and safety of the components and buildings. When the structure is subjected to stress, there is a certain relative shear deformation between the prefabricated part and the cast-in-place concrete part of the concrete composite component. The shear deformation and shear stress state on the composite surface are important indicators for evaluating the overall working performance of concrete composite components.

[0004] In the related art, two concrete strain gauges are fixed at an angle crosswise by adhesive tape or iron wire and buried in the prefabricated part in advance. It is difficult to maintain the angle between the two concrete strain gauges at a preset angle. Therefore, when the shear stress of the overlapping surface is calculated according to the preset angle by combining the measurement data of the concrete strain gauges, the calculation results will produce uncontrollable deviations, making it difficult to make a correct assessment of the overall working performance of the concrete composite member. Summary of the invention

[0005] An object of the present invention is to provide a fixing member that enables two concrete strain gauges to be cross-fixed at a preset angle, thereby facilitating improving the accuracy of the measurement results of the concrete strain gauges.

[0006] Another object of the present invention is to provide a stress testing device having the above-mentioned fixing member, so as to improve the accuracy of the measurement result.

[0007] Another object of the present invention is to provide a testing method, which uses the above-mentioned stress testing device to improve the accuracy of the measurement results.

[0008] In order to achieve at least one of the above purposes, the technical solution adopted by the present invention is: a fixing piece for fixing a concrete strain gauge, comprising a fixing part, the fixing part having a first side surface and a second side surface arranged opposite to each other, the first side surface having a first fixing structure suitable for clamping the concrete strain gauge so that the concrete strain gauge is fixed to the first side surface of the fixing part along a first direction; the second side surface having a second fixing structure suitable for clamping the concrete strain gauge so that the concrete strain gauge is fixed to the second side surface of the fixing part along a second direction; the first direction and the second direction form an angle so that the two concrete strain gauges are cross-clamped on the fixing piece.

[0009] As a preference, the fixing portion has a accommodating cavity, which penetrates the fixing portion along the third direction and is used to accommodate the sensor of the concrete strain gauge; a pair of first fixing grooves are provided on the first side surface of the fixing portion, the first fixing grooves are suitable for clamping the force transmission rod of the concrete strain gauge, and the two first fixing grooves are arranged at intervals along the first direction so that the concrete strain gauge is fixed along the first direction; a pair of second fixing grooves are provided on the second side surface of the fixing portion, the second fixing grooves are suitable for clamping the force transmission rod of the concrete strain gauge, and the two second fixing grooves are arranged at intervals along the second direction so that the concrete strain gauge is fixed along the second direction.

[0010] As a preferred embodiment, the fixing member further includes a frame portion and a reinforcing rib, the frame portion is located on the outer peripheral side of the fixing portion, the reinforcing rib connects the frame portion and the fixing portion, the frame portion has a first side and a second side that are oppositely arranged, the first side is provided with a pair of first auxiliary grooves, the first auxiliary grooves are suitable for clamping the force transmission rod of the concrete strain gauge, and the two first auxiliary grooves are spaced apart along the first direction to fix the concrete strain gauge placed on the fixing portion along the first direction; the second side is provided with a pair of second auxiliary grooves, the second auxiliary grooves are suitable for clamping the force transmission rod of the concrete strain gauge, and the two second auxiliary grooves are spaced apart along the second direction to fix the concrete strain gauge placed on the fixing portion along the second direction.

[0011] As a preferred embodiment, the frame portion includes a main body portion and a connecting portion, the main body portion includes four main walls, the four main walls are respectively located at the four sides of the virtual rectangle, the connecting portion includes a pair of first connecting walls and a pair of second connecting walls, each of the first connecting walls and each of the second connecting walls are located at the corners of the virtual rectangle to connect two adjacent main walls; the two first connecting walls are perpendicular to the first direction and are spaced apart along the first direction, and the first connecting walls are provided with a first auxiliary groove to fix the concrete strain gauge placed on the fixing portion along the first direction; the two second connecting walls are perpendicular to the second direction and are spaced apart along the second direction, and the second connecting walls are provided with a second auxiliary groove to fix the concrete strain gauge placed on the fixing portion along the second direction.

[0012] As a preference, the frame portion and the fixing portion are concentric, and the frame portion further comprises a positioning structure, and the positioning structure is centrally arranged on the main wall.

[0013] As a preference, the positioning structure is a positioning notch, and the positioning notch is opened on the first side edge and / or the second side edge of the main wall.

[0014] As a preference, the reinforcing rib is located on the center line of the virtual rectangle to connect the main wall and the fixing portion.

[0015] Preferably, the first fixing groove, the second fixing groove, and / or the first auxiliary groove, the second auxiliary groove include a accommodating area and a limiting area, the accommodating area is connected with the outside through the limiting area, the accommodating area is suitable for placing the force transmission rod of the concrete strain gauge, and the width of the limiting area is smaller than the diameter of the force transmission rod so that the force transmission rod can be squeezed through the limiting area and retained in the accommodating area.

[0016] In order to achieve at least one of the above purposes, the technical solution adopted by the present invention is: a stress testing device, comprising any of the above-described fixings, and two concrete strain gauges, wherein the concrete strain gauges include sensors, force transmission rods arranged at both ends of the sensors, and discs located at the ends of the force transmission rods, and the two sensors are accommodated in the accommodating cavity of the fixing, wherein the force transmission rod of one of the sensors is clamped with the first fixing groove and the first auxiliary groove of the fixing, and the force transmission rod of the other sensor is clamped with the second fixing groove and the second auxiliary groove of the fixing, so that the two sensors are cross-fixed to the fixing, and the discs of the two sensors are both located on the outside of the fixing.

[0017] In order to achieve at least one of the above purposes, the technical solution adopted by the present invention is: a stress testing method, using any of the above-mentioned fixing members, comprising the steps of:

[0018] S1. Provide a fixing member and two concrete strain gauges, and install the two concrete strain gauges on the fixing member to obtain a stress testing device;

[0019] S2, pouring the prefabricated parts and setting the truss reinforcement;

[0020] S3, inserting at least one of the stress testing devices into the prefabricated part in advance, so that the positioning structure of the fixing member is flush with the overlapping surface of the prefabricated part in advance and the cast-in-place part in the later stage;

[0021] S4. After the standard curing period, a graded loading test is performed to obtain the normal stress and shear stress measured by the two concrete strain gauges in the stress testing device. According to the formula Calculate the shear stress of the overlapped surface, where τ x is the shear stress of the superimposed surface, τ α is the normal stress measured by one of the concrete strain gauges, σ y is the normal stress measured by another concrete strain gauge, and α is the angle between the concrete strain gauge and the superposition surface.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] Through the first fixing structure arranged on the first side of the fixing part, a concrete strain gauge can be clamped and fixed along the first direction, and through the second fixing structure arranged on the second side of the fixing part, another concrete strain gauge can be clamped and fixed along the second direction, and the first direction and the second direction form an angle, so that the two concrete strain gauges can be maintained at an angle by the fixing member. Further, the two concrete strain gauges are respectively fixed to the two oppositely arranged side surfaces of the fixing part, that is, the concrete strain gauges are installed with the fixing part as the reference, so that the two concrete strain gauges do not interfere with each other, which is conducive to improving the accuracy and reliability of positioning. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the structure of a fixing member according to some embodiments of the present application.

[0025] Figure 2 It is a schematic diagram of the structure of a fixing member according to some embodiments of the present application.

[0026] Figure 3 is a schematic structural diagram of a stress testing device according to some embodiments of the present application.

[0027] Figure 4 is a side view of a fixing member according to some embodiments of the present application.

[0028] Figure 5It is a schematic diagram of a stress testing device arranged on a concrete composite member according to some embodiments of the present application.

[0029] Figure 6 It is a schematic structural diagram of a fixing member according to other embodiments of the present application.

[0030] Figure 7 is a schematic structural diagram of a stress testing device according to other embodiments of the present application.

[0031] Figure 8 It is a schematic diagram of a stress testing device arranged on a concrete composite member according to some other embodiments of the present application.

[0032] Fig. 9 It is a schematic diagram of a stress testing device arranged on a concrete composite member according to some other embodiments of the present application.

[0033] In the figure: 10, fixing part; 11, first side; 12, first fixing structure; 121, first fixing groove; 13, second side; 14, second fixing structure; 141, second fixing groove; 15, accommodating cavity; 20, frame part; 21, first side; 22, second side; 23, main body; 231, main wall; 2311, positioning structure; 24, connecting part; 241, first connecting wall; 2411, first auxiliary groove; 242, second connecting wall; 2421, second auxiliary groove; 30, reinforcing rib; 41, accommodating area; 42, limiting area; 50, concrete strain gauge; 51, sensor; 52, force transmission rod; 53, disc; 60, concrete composite member; 61, prefabricated part in advance; 62, cast-in-place part in the later stage; 63, composite surface. DETAILED DESCRIPTION

[0034] The present invention is further described below in conjunction with specific implementation methods. It should be noted that, under the premise of no conflict, the various embodiments or technical features described below can be arbitrarily combined to form a new embodiment.

[0035] In the description of the present invention, it should be noted that directional words, such as the terms "center", "lateral", "longitudinal", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", etc., indicating directions and positional relationships are based on the directions or positional relationships shown in the accompanying drawings, which are only for the convenience of narrating the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and cannot be understood as limiting the specific scope of protection of the present invention.

[0036] It should be noted that the terms "first", "second", etc. in the description and claims of the present application are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence.

[0037] A fixing member, such as Figure 1-Figure 3 As shown, the device is used to fix the concrete strain gauge 50, and includes a fixing part 10, wherein the fixing part 10 has a first side surface 11 and a second side surface 13 arranged opposite to each other, and the first side surface 11 has a first fixing structure 12 suitable for clamping the concrete strain gauge 50, so that the concrete strain gauge 50 is fixed to the first side surface 11 of the fixing part 10 along a first direction; the second side surface 13 has a second fixing structure 14 suitable for clamping the concrete strain gauge 50, so that the concrete strain gauge 50 is fixed to the second side surface 13 of the fixing part 10 along a second direction. The first direction and the second direction form an angle, so that the two concrete strain gauges 50 are cross-clamped on the fixing part.

[0038] In the related art, two concrete strain gauges are fixed by wrapping tape or wire, which makes it difficult for construction workers to operate independently. Moreover, when the concrete strain gauges are inserted into the concrete, the two concrete strain gauges are prone to relative movement, resulting in uncontrollable deviations in the measurement results.

[0039] In this embodiment, a concrete strain gauge 50 is clamped and fixed along a first direction by a first fixing structure 12 disposed on a first side surface 11 of the fixing portion 10, and another concrete strain gauge 50 is clamped and fixed along a second direction by a second fixing structure 14 disposed on a second side surface 13 of the fixing portion 10, and the first direction and the second direction form an angle, so that the two concrete strain gauges 50 can be maintained at an angle by the fixing member. In addition, the two concrete strain gauges 50 are respectively clamped and fixed to the fixing portion 10, so that construction personnel can operate them separately.

[0040] Furthermore, the two concrete strain gauges 50 are respectively fixed to two oppositely disposed side surfaces of the fixing portion 10 , that is, the concrete strain gauges 50 are installed based on the fixing portion 10 so that the two concrete strain gauges 50 do not interfere with each other, which is beneficial to improving the accuracy and reliability of positioning.

[0041] It is worth mentioning that the normal stress measured by the concrete strain gauge 50 fixed along the first direction is along the first direction, and the normal stress measured by the concrete strain gauge 50 fixed along the second direction is along the second direction. The angle between the first direction and the second direction is denoted as β. In a specific embodiment, Figure 8 As shown, β = 60°, so it is suitable for thinner concrete composite components 60. In another specific embodiment, as shown in FIG. Figure 5 As shown, β = 90°. In another specific embodiment, Fig. 9As shown, β=120°, so that it is applicable to the concrete composite member 60 with a narrow width.

[0042] In some embodiments, Figure 1-Figure 3 , Figure 6 and Figure 7 As shown, the fixing portion 10 has a receiving cavity 15, which penetrates the fixing portion 10 along the third direction and is used to receive the sensor 51 of the concrete strain gauge 50, wherein the third direction is perpendicular to the first direction and the second direction. The first side surface 11 of the fixing portion 10 is provided with a pair of first fixing grooves 121, the first fixing grooves 121 are suitable for clamping the force transmission rod 52 of the concrete strain gauge 50, and the two first fixing grooves 121 are arranged at intervals along the first direction so that the concrete strain gauge 50 is fixed along the first direction. The second side surface 13 of the fixing portion 10 is provided with a pair of second fixing grooves 141, the second fixing grooves 141 are suitable for clamping the force transmission rod 52 of the concrete strain gauge 50, and the two second fixing grooves 141 are arranged at intervals along the second direction so that the concrete strain gauge 50 is fixed along the second direction.

[0043] Specifically, the concrete strain gauge 50 includes a sensor 51, a force transmission rod 52 disposed at both ends of the sensor 51, and a disc 53 located at the end of the force transmission rod 52. The opening of the first fixing groove 121 faces the first side surface 11 of the fixing portion 10, so that the force transmission rod 52 of a concrete strain gauge 50 is suitable for being inserted into the first fixing groove 121 along the third direction, and the sensor 51 of the concrete strain gauge 50 is accommodated in the accommodation cavity 15. Further, the two first fixing grooves 121 are arranged at intervals along the first direction, so that the force transmission rod 52 of the sensor 51 extends along the first direction, and thus the normal stress measured by the concrete sensor 51 is along the first direction.

[0044] Similarly, the opening of the second fixing groove 141 faces the second side surface 13 of the fixing portion 10, so that the force transmission rod 52 of another concrete strain gauge 50 is suitable for being inserted into the second fixing groove 141 along the third direction, and the sensor 51 of the concrete strain gauge 50 is accommodated in the accommodating cavity 15. Furthermore, the two second fixing grooves 141 are arranged at intervals along the second direction, so that the force transmission rod 52 of the sensor 51 extends along the second direction, thereby making the positive stress measured by the concrete sensor 51 along the second direction.

[0045] It is worth mentioning that the axis of the concrete strain gauge 50 arranged along the first direction is recorded as the first axis, and the axis of the concrete strain gauge 50 arranged along the second direction is recorded as the second axis. Furthermore, the plane parallel to the first axis and the second axis and equidistant from the first axis and the second axis is recorded as a common plane. Ideally, the common plane is perpendicular to the third direction. That is to say, when the fixing parts clamping the two concrete strain gauges 50 are arranged on the prefabricated part 61, the common plane is perpendicular to the overlapping surface 63 of the prefabricated part 61 and the cast-in-place part 62, so that the measurement result of the concrete sensor 51 is more accurate.

[0046] Specifically, through the arrangement direction of the two first fixing grooves 121 set at intervals, one concrete strain gauge 50 can be arranged along the first direction, and through the arrangement direction of the two second fixing grooves 141 set at intervals, another concrete strain gauge 50 can be arranged along the second direction, thereby maintaining the angle β between the two concrete strain gauges 50. Further, through the two first fixing grooves 121 and the two second fixing grooves 141, the directions of the first axis and the second axis can be restricted respectively, so that the common plane is perpendicular to the third direction. It can be understood that the two concrete strain gauges 50 are respectively clamped and matched with the fixing part 10, which is conducive to avoiding interference between the two concrete strain gauges 50, thereby improving the accuracy of the positioning of the concrete strain gauge 50 and improving the connection reliability of the concrete strain gauge 50 and the fixing part 10.

[0047] It is worth mentioning that the shorter the distance between the first axis and the second axis of the two concrete strain gauges 50 and the common plane, the closer the measurement result of the concrete strain gauge 50 is to the normal stress in the common plane, which is conducive to improving the accuracy of the measurement result. In other words, when the two concrete strain gauges 50 are installed on the fixing part 10, the smaller the spacing between the two concrete strain gauges 50 along the third direction, the more conducive to improving the accuracy of the measurement result. In a specific embodiment, when the force transmission rods 52 of the two concrete strain gauges 50 are clamped in the first fixing groove 121 and the second fixing groove 141 respectively, the sensors 51 of the two concrete strain gauges 50 fit each other in the accommodating cavity 15.

[0048] In at least one implementation, Figure 3 and Figure 7 As shown, the fixing portion 10 is in a circular ring shape, and the sensor 51 of the concrete strain gauge 50 is inscribed in the inner wall of the fixing portion 10, so that the concrete strain gauge 50 can be positioned in the first direction and the second direction, which is beneficial to avoid the concrete strain gauge 50 from moving along its axial direction, thereby improving the positioning reliability of the fixing portion 10 for the concrete strain gauge 50, and is beneficial to make the projections of the centers of the two concrete strain gauges 50 in the third direction coincide, thereby making the measurement result more accurate.

[0049] In some embodiments, Figure 1-Figure 3 , Figure 6 and Figure 7 As shown, the fixing member further includes a frame portion 20 and a reinforcing rib 30. The frame portion 20 is located on the outer peripheral side of the fixing portion 10. The reinforcing rib 30 connects the frame portion 20 and the fixing portion 10. The frame portion 20 has a first side 21 and a second side 22 that are arranged opposite to each other. The first side 21 is provided with a pair of first auxiliary grooves 2411. The first auxiliary grooves 2411 are suitable for clamping the force transmission rod 52 of the concrete strain gauge 50. The two first auxiliary grooves 2411 are arranged at intervals along the first direction to fix the concrete strain gauge 50 placed on the fixing portion 10 along the first direction. The second side 22 is provided with a pair of second auxiliary grooves 2421. The second auxiliary grooves 2421 are suitable for clamping the force transmission rod 52 of the concrete strain gauge 50. The two second auxiliary grooves 2421 are arranged at intervals along the second direction to fix the concrete strain gauge 50 placed on the fixing portion 10 along the second direction.

[0050] It can be understood that the first side edge 21 of the frame portion 20 and the first side surface 11 of the fixing portion 10 are located on the same side of the fixing member, and the second side edge 22 of the frame portion 20 and the second side surface 13 of the fixing portion 10 are located on the other side of the fixing member. Furthermore, the force transmission rod 52 of the concrete strain gauge 50 can be further clamped by the first auxiliary groove 2411 and the second auxiliary groove 2421 of the frame portion 20, which is conducive to reducing the influence of the bending of the force transmission rod 52 on the measurement result, so as to improve the fixing reliability of the fixing member to the concrete strain gauge 50, and is conducive to further improving the accuracy of the measurement result.

[0051] In at least one embodiment, Figure 1 and Figure 2 As shown, the frame portion 20 includes a main body portion 23 and a connecting portion 24, the main body portion 23 includes four main walls 231, and the four main walls 231 are respectively located at the four sides of the virtual rectangle, and the connecting portion 24 includes a pair of first connecting walls 241 and a pair of second connecting walls 242, each of the first connecting walls 241 and each of the second connecting walls 242 are located at the corners of the virtual rectangle to connect two adjacent main walls 231; the two first connecting walls 241 are perpendicular to the first direction and are spaced apart along the first direction, and the first connecting walls 241 are provided with a first auxiliary groove 2411 to fix the concrete strain gauge 50 placed on the fixing portion 10 along the first direction; the two second connecting walls 242 are perpendicular to the second direction and are spaced apart along the second direction, and the second connecting walls 242 are provided with a second auxiliary groove 2421 to fix the concrete strain gauge 50 placed on the fixing portion 10 along the second direction.

[0052] It can be understood that one pair of oppositely disposed main walls 231 is suitable for being parallel to the overlapping surface 63, and the other pair of oppositely disposed main walls 231 is suitable for being perpendicular to the overlapping surface 63. Furthermore, by embedding the main walls 231 in the prefabricated part 61, the fixing parts clamping the two concrete strain gauges 50 can be maintained in the prefabricated part 61, which is conducive to making the common plane perpendicular to the overlapping surface 63.

[0053] In the related art, two concrete strain gauges 50 are fixed by wrapping adhesive tape or iron wire. In the direction perpendicular to the overlapped surface 63, the support force of concrete on the two concrete strain gauges 50 is small, and the shared plane is prone to be skewed. In this embodiment, by embedding the main wall 231 parallel to the overlapped surface 63 in the prefabricated part 61, it is helpful to increase the support force of concrete on the fixing member in the direction perpendicular to the overlapped surface 63, and it is helpful to keep the shared plane perpendicular to the overlapped surface 63, so as to further improve the accuracy of the measurement result.

[0054] It is worth mentioning that the first connecting wall 241 is perpendicular to the first direction, which is conducive to reducing the influence of the first connecting wall 241 on the force of the force transmission rod 52 of the concrete strain gauge 50 along the first direction, thereby making the normal stress measured by the concrete strain gauge 50 more accurate. Similarly, the second connecting wall 242 is perpendicular to the second direction, which is conducive to reducing the influence of the second connecting wall 242 on the force of the force transmission rod 52 of the concrete strain gauge 50 along the second direction, thereby making the normal stress measured by the concrete strain gauge 50 more accurate.

[0055] In some embodiments, Figure 2 As shown, the frame portion 20 and the fixing portion 10 are concentric, and the frame portion 20 further includes a positioning structure 2311, which is centrally arranged on the main wall 231. In other words, the line connecting the positioning structures 2311 on the two main walls 231 passes through the center of the fixing portion 10. In an ideal case, the angles between the two concrete strain gauges 50 and the superposition surface 63 are consistent, both α=β / 2, and the center of the fixing portion 10 is located on the superposition surface 63, that is, the centers of the two concrete strain gauges 50 are located on the superposition surface 63. It can be understood that when the fixing part is placed in the prefabricated part 61, it is convenient to observe the depth of the fixing part and whether it is kept horizontal through the positioning structure 2311 on the main wall 231. Ideally, the positioning structure 2311 on a pair of main walls 231 perpendicular to the overlapping surface 63 is flush with the overlapping surface 63, so that the angles between the two concrete strain gauges 50 and the overlapping surface 63 are consistent, and the center of the fixing part 10 is located on the overlapping surface 63.

[0056] In some embodiments, the positioning structure 2311 is a positioning notch, which is convenient for observation. The positioning notch is provided on the first side 21 and / or the second side 22 of the main wall 231. Specifically, the cross section of the positioning notch can be "U"-shaped, "I"-shaped, or triangular. In a specific embodiment, the first side 21 and the second side 22 of each main wall 231 are provided with a positioning notch, and the cross section of the positioning notch is an isosceles triangle. Furthermore, the vertex of the positioning notch is located at the midline position of the main wall 231 along the length direction.

[0057] It can be understood that the top angles of the two positioning notches on the same main wall 231 are relatively set. When the fixing piece is placed on the prefabricated part 61, the relatively set top angles make it easy to observe whether the fixing piece is placed at an angle, which is conducive to making the common plane perpendicular to the overlapping surface 63.

[0058] It is worth mentioning that the positioning structure 2311 can also be a raised or recessed line on the outer side of the main wall 231, or a raised or recessed dot on the outer side of the main wall 231, and the present application does not impose any specific restrictions on this.

[0059] In some embodiments, the reinforcing rib 30 is located on the center line of the virtual rectangle to connect the main wall 231 and the fixing portion 10. In other words, the extending direction of the reinforcing rib 30 coincides with the connecting line of the positioning structures 2311 on the two main walls 231, and when the fixing piece is placed on the previously prefabricated part, the reinforcing rib 30 can be used to assist in observing the embedding depth of the fixing piece and whether it is tilted.

[0060] In some embodiments, Figure 4 As shown, the first fixing groove 121, the second fixing groove 141, and / or the first auxiliary groove 2411, the second auxiliary groove 2421 include a accommodating area 41 and a limiting area 42. The accommodating area 41 is connected to the outside through the limiting area 42. The accommodating area 41 is suitable for placing the force transmitting rod 52 of the concrete strain gauge 50. The width of the limiting area 42 is smaller than the diameter of the force transmitting rod 52, so that the force transmitting rod 52 can be squeezed through the limiting area 42 and retained in the accommodating area 41.

[0061] It is understandable that the groove wall of the accommodating area 41 is suitable for fitting the force transmission rod 52 of the concrete strain gauge 50, thereby preventing the force transmission rod 52 from shaking relative to the fixing portion 10 and the frame portion 20, which is beneficial to improving the fixing reliability of the fixing piece to the concrete strain gauge 50. The width of the limiting area 42 is slightly smaller than the diameter of the force transmission rod 52, so that the force transmission rod 52 can enter the accommodating area 41 through the limiting area 42 and can be kept in the accommodating area 41, which is beneficial to preventing the concrete strain gauge 50 from being separated from the fixing piece, thereby improving the connection reliability of the concrete strain gauge 50 and the fixing piece. It is worth mentioning that the construction personnel can press the concrete strain gauge 50 to make the force transmission rod 52 of the concrete strain gauge 50 snap into each fixing piece slot and / or each auxiliary slot into the accommodating area 41, thereby quickly and conveniently completing the installation of the concrete strain gauge 50 and the fixing piece.

[0062] A stress testing device comprises the above fixing member, and two concrete strain gauges 50, the concrete strain gauge 50 comprises a sensor 51, a force transmission rod 52 arranged at both ends of the sensor 51 and a disc 53 located at the end of the force transmission rod 52, the two sensors 51 are accommodated in the accommodating cavity 15 of the fixing member, the force transmission rod 52 of one sensor 51 is clamped with the first fixing groove 121 and the first auxiliary groove 2411 of the fixing member, and the force transmission rod 52 of the other sensor 51 is clamped with the second fixing groove 141 and the second auxiliary groove 2421 of the fixing member, so that the two sensors 51 are cross-fixed to the fixing member, and the discs 53 of the two sensors 51 are both located on the outside of the fixing member.

[0063] It can be understood that the fixing member of the stress testing device is conducive to keeping the two concrete strain gauges 50 cross-fixed at a preset angle β, and the main wall 231 of the fixing member is conducive to keeping the common plane perpendicular to the overlapping surface 63, thereby facilitating improving the accuracy of the results measured by the stress testing device.

[0064] A stress testing method, using the above fixing member, comprises the following steps:

[0065] S1, providing a fixing member and two concrete strain gauges 50, and installing the two concrete strain gauges 50 on the fixing member to obtain a stress testing device;

[0066] S2, pouring the prefabricated part 61 and setting truss reinforcement;

[0067] S3, inserting at least one stress testing device into the prefabricated part 61, so that the positioning structure 2311 of the fixing member is flush with the overlapping surface 63 of the prefabricated part 61 and the later cast-in-place part 62, that is, flush with the surface of the prefabricated part 61;

[0068] S4. After the standard curing period, a graded loading test is performed to obtain the normal stress and shear stress measured by the two concrete strain gauges 50 in the stress testing device. According to the formula Calculate the shear stress of the overlapped surface 63, where τ α is the shear stress of the superimposed surface 63, σ x is the normal stress measured by one of the concrete strain gauges 50, σ y is the normal stress measured by another concrete strain gauge 50 , and α is the angle between the concrete strain gauge 50 and the superposition surface 63 .

[0069] Specifically, step S2 also includes fixing the fixing member to the truss reinforcement, so as to further improve the reliability of placing the stress testing device in the prefabricated part 61 and reduce the risk of the stress testing device being skewed due to external force.

[0070] In step S4, the standard curing period can be adjusted according to the actual situation. In a specific embodiment, the standard curing period is 18 days. Figure 5 As shown, the shear stress formula of the overlapped surface 63 is derived as follows:

[0071]

[0072]

[0073] Among them, σ x , σ y are the normal stresses in their respective directions measured by the two concrete strain gauges 50; τ x , τ y are the shear stresses in respective directions measured by the two concrete strain gauges 50; σ1 and σ2 are the calculated plane principal stresses.

[0074] According to the stress circle, we can get:

[0075]

[0076] Wherein, α is the angle between the concrete strain gauge 50 and the superposition surface 63 .

[0077] From formula (1-3), we can get:

[0078]

[0079] According to the shear stress formula of the inclined section, we can get:

[0080]

[0081] Substituting equation (1-4) into equation (1-5), the shear stress formula of the overlap surface 63 can be obtained as follows:

[0082]

[0083] τ α It is the calculated shear stress on the overlapped surface of the concrete member.

[0084] In a specific implementation, a stress testing device is provided on each side of the truss bar, and the angle between the concrete strain gauge 50 of each stress testing device and the overlap surface 63 is 45°, then the shear stress calculation formula (1-6) of the overlap surface can be simplified to: Furthermore, the normal stresses measured by the two concrete strain gauges 50 of one stress testing device are σ x1 =3.42MPa,σ y1 =1.14MPa; the positive stresses measured by the two concrete strain gauges 50 of the other stress testing device are σ x2 =40.64MPa,σ y2 =31.49MPa; Furthermore, the shear stress of the overlapped surface 63 on both sides of the truss reinforcement is calculated by formula (1-7):

[0085] The above describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions only describe the principles of the present invention. The present invention may be subject to various changes and improvements without departing from the spirit and scope of the present invention. These changes and improvements fall within the scope of the present invention to be protected. The scope of protection claimed by the present invention is defined by the attached claims and their equivalents.

Claims

1. A fixing member for fixing a concrete strain gauge, characterized in that: The invention comprises a fixing part, a frame part and a reinforcing rib, wherein the frame part is located at the outer peripheral side of the fixing part, and the frame part and the fixing part are concentric, the reinforcing rib connects the frame part and the fixing part, the fixing part has a first side surface and a second side surface which are arranged opposite to each other, the first side surface has a first fixing structure which is suitable for clamping the concrete strain gauge, so that the concrete strain gauge is fixed to the first side surface of the fixing part along a first direction; the second side surface has a second fixing structure which is suitable for clamping the concrete strain gauge, so that the concrete strain gauge is fixed to the second side surface of the fixing part along a second direction; the first direction and the second direction form an angle, so that the two concrete strain gauges are cross-clamped to the fixing part; the fixing part has a containing cavity, the The accommodating cavity penetrates the fixing portion along the third direction, and is used to accommodate the sensor of the concrete strain gauge; a pair of first fixing grooves are provided on the first side surface of the fixing portion, and the first fixing grooves are suitable for clamping the force transmission rod of the concrete strain gauge, and the two first fixing grooves are arranged at intervals along the first direction so that the concrete strain gauge is fixed along the first direction; a pair of second fixing grooves are provided on the second side surface of the fixing portion, and the second fixing grooves are suitable for clamping the force transmission rod of the concrete strain gauge, and the two second fixing grooves are arranged at intervals along the second direction so that the concrete strain gauge is fixed along the second direction; the frame portion includes a main body and a positioning structure, and the main body includes four main walls, and the four main walls are respectively located on the four sides of the virtual rectangle, and the positioning structure is centrally arranged on the main wall.

2. The fixing member according to claim 1, characterized in that: The frame portion has a first side and a second side that are oppositely arranged, the first side is provided with a pair of first auxiliary grooves, the first auxiliary grooves are suitable for clamping the force transmission rod of the concrete strain gauge, and the two first auxiliary grooves are arranged at intervals along the first direction to fix the concrete strain gauge placed on the fixing portion along the first direction; the second side is provided with a pair of second auxiliary grooves, the second auxiliary grooves are suitable for clamping the force transmission rod of the concrete strain gauge, and the two second auxiliary grooves are arranged at intervals along the second direction to fix the concrete strain gauge placed on the fixing portion along the second direction.

3. The fixing member according to claim 2, characterized in that: The frame portion includes a connecting portion, and the connecting portion includes a pair of first connecting walls and a pair of second connecting walls, each of the first connecting walls and each of the second connecting walls are located at the corners of a virtual rectangle to connect two adjacent main walls; the two first connecting walls are perpendicular to a first direction and are spaced apart along the first direction, and a first auxiliary groove is provided on the first connecting wall to fix the concrete strain gauge placed on the fixing portion along the first direction; the two second connecting walls are perpendicular to a second direction and are spaced apart along the second direction, and a second auxiliary groove is provided on the second connecting wall to fix the concrete strain gauge placed on the fixing portion along the second direction.

4. The fixing member according to claim 3, characterized in that: The positioning structure is a positioning notch, and the positioning notch is opened on the first side edge and / or the second side edge of the main wall.

5. The fixing member according to any one of claims 3-4, characterized in that: The reinforcing rib is located on the center line of the virtual rectangle to connect the main wall and the fixing portion.

6. The fixing member according to any one of claims 2 to 4, characterized in that: The first fixing groove, the second fixing groove, and / or the first auxiliary groove, the second auxiliary groove include a accommodating area and a limiting area. The accommodating area is connected to the outside through the limiting area. The accommodating area is suitable for placing the force transmission rod of the concrete strain gauge. The width of the limiting area is smaller than the diameter of the force transmission rod so that the force transmission rod can be squeezed through the limiting area and retained in the accommodating area.

7. A stress testing device, characterized in that: It comprises a fixing member as described in any one of claims 1 to 6, and two concrete strain gauges, wherein the concrete strain gauge comprises a sensor, a force transmission rod arranged at both ends of the sensor, and a disc located at the end of the force transmission rod, the two sensors are accommodated in the accommodating cavity of the fixing member, the force transmission rod of one of the sensors is clamped with the first fixing groove and the first auxiliary groove of the fixing member, and the force transmission rod of the other sensor is clamped with the second fixing groove and the second auxiliary groove of the fixing member, so that the two sensors are cross-fixed to the fixing member, and the discs of the two sensors are both located on the outside of the fixing member.

8. A stress testing method, characterized in that: Using the fixing member as described in any one of claims 1 to 6, comprising the steps of: S1. Provide a fixing member and two concrete strain gauges, and install the two concrete strain gauges on the fixing member to obtain a stress testing device; S2, pouring the prefabricated parts and setting the truss reinforcement; S3, inserting at least one of the stress testing devices into the prefabricated part in advance, so that the positioning structure of the fixing member is flush with the overlapping surface of the prefabricated part in advance and the cast-in-place part in the later stage; S4. After the standard curing period, a graded loading test is performed to obtain the normal stress and shear stress measured by the two concrete strain gauges in the stress testing device. According to the formula Calculate the shear stress of the overlapped surface, where is the shear stress of the superimposed surface, is the normal stress measured by one of the concrete strain gauges, is the normal stress measured by another concrete strain gauge, is the angle between the concrete strain gauge and the superposition surface.

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